xref: /linux/tools/lib/bpf/libbpf.c (revision d0d106a2bd21499901299160744e5fe9f4c83ddb)
1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2 
3 /*
4  * Common eBPF ELF object loading operations.
5  *
6  * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
7  * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
8  * Copyright (C) 2015 Huawei Inc.
9  * Copyright (C) 2017 Nicira, Inc.
10  * Copyright (C) 2019 Isovalent, Inc.
11  */
12 
13 #ifndef _GNU_SOURCE
14 #define _GNU_SOURCE
15 #endif
16 #include <stdlib.h>
17 #include <stdio.h>
18 #include <stdarg.h>
19 #include <libgen.h>
20 #include <inttypes.h>
21 #include <limits.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <endian.h>
25 #include <fcntl.h>
26 #include <errno.h>
27 #include <ctype.h>
28 #include <asm/unistd.h>
29 #include <linux/err.h>
30 #include <linux/kernel.h>
31 #include <linux/bpf.h>
32 #include <linux/btf.h>
33 #include <linux/filter.h>
34 #include <linux/limits.h>
35 #include <linux/perf_event.h>
36 #include <linux/bpf_perf_event.h>
37 #include <linux/ring_buffer.h>
38 #include <sys/epoll.h>
39 #include <sys/ioctl.h>
40 #include <sys/mman.h>
41 #include <sys/stat.h>
42 #include <sys/types.h>
43 #include <sys/vfs.h>
44 #include <sys/utsname.h>
45 #include <sys/resource.h>
46 #include <libelf.h>
47 #include <gelf.h>
48 #include <zlib.h>
49 
50 #include "libbpf.h"
51 #include "bpf.h"
52 #include "btf.h"
53 #include "str_error.h"
54 #include "libbpf_internal.h"
55 #include "hashmap.h"
56 #include "bpf_gen_internal.h"
57 #include "zip.h"
58 
59 #ifndef BPF_FS_MAGIC
60 #define BPF_FS_MAGIC		0xcafe4a11
61 #endif
62 
63 #define BPF_FS_DEFAULT_PATH "/sys/fs/bpf"
64 
65 #define BPF_INSN_SZ (sizeof(struct bpf_insn))
66 
67 /* vsprintf() in __base_pr() uses nonliteral format string. It may break
68  * compilation if user enables corresponding warning. Disable it explicitly.
69  */
70 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
71 
72 #define __printf(a, b)	__attribute__((format(printf, a, b)))
73 
74 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
75 static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
76 static int map_set_def_max_entries(struct bpf_map *map);
77 
78 static const char * const attach_type_name[] = {
79 	[BPF_CGROUP_INET_INGRESS]	= "cgroup_inet_ingress",
80 	[BPF_CGROUP_INET_EGRESS]	= "cgroup_inet_egress",
81 	[BPF_CGROUP_INET_SOCK_CREATE]	= "cgroup_inet_sock_create",
82 	[BPF_CGROUP_INET_SOCK_RELEASE]	= "cgroup_inet_sock_release",
83 	[BPF_CGROUP_SOCK_OPS]		= "cgroup_sock_ops",
84 	[BPF_CGROUP_DEVICE]		= "cgroup_device",
85 	[BPF_CGROUP_INET4_BIND]		= "cgroup_inet4_bind",
86 	[BPF_CGROUP_INET6_BIND]		= "cgroup_inet6_bind",
87 	[BPF_CGROUP_INET4_CONNECT]	= "cgroup_inet4_connect",
88 	[BPF_CGROUP_INET6_CONNECT]	= "cgroup_inet6_connect",
89 	[BPF_CGROUP_UNIX_CONNECT]       = "cgroup_unix_connect",
90 	[BPF_CGROUP_INET4_POST_BIND]	= "cgroup_inet4_post_bind",
91 	[BPF_CGROUP_INET6_POST_BIND]	= "cgroup_inet6_post_bind",
92 	[BPF_CGROUP_INET4_GETPEERNAME]	= "cgroup_inet4_getpeername",
93 	[BPF_CGROUP_INET6_GETPEERNAME]	= "cgroup_inet6_getpeername",
94 	[BPF_CGROUP_UNIX_GETPEERNAME]	= "cgroup_unix_getpeername",
95 	[BPF_CGROUP_INET4_GETSOCKNAME]	= "cgroup_inet4_getsockname",
96 	[BPF_CGROUP_INET6_GETSOCKNAME]	= "cgroup_inet6_getsockname",
97 	[BPF_CGROUP_UNIX_GETSOCKNAME]	= "cgroup_unix_getsockname",
98 	[BPF_CGROUP_UDP4_SENDMSG]	= "cgroup_udp4_sendmsg",
99 	[BPF_CGROUP_UDP6_SENDMSG]	= "cgroup_udp6_sendmsg",
100 	[BPF_CGROUP_UNIX_SENDMSG]	= "cgroup_unix_sendmsg",
101 	[BPF_CGROUP_SYSCTL]		= "cgroup_sysctl",
102 	[BPF_CGROUP_UDP4_RECVMSG]	= "cgroup_udp4_recvmsg",
103 	[BPF_CGROUP_UDP6_RECVMSG]	= "cgroup_udp6_recvmsg",
104 	[BPF_CGROUP_UNIX_RECVMSG]	= "cgroup_unix_recvmsg",
105 	[BPF_CGROUP_GETSOCKOPT]		= "cgroup_getsockopt",
106 	[BPF_CGROUP_SETSOCKOPT]		= "cgroup_setsockopt",
107 	[BPF_SK_SKB_STREAM_PARSER]	= "sk_skb_stream_parser",
108 	[BPF_SK_SKB_STREAM_VERDICT]	= "sk_skb_stream_verdict",
109 	[BPF_SK_SKB_VERDICT]		= "sk_skb_verdict",
110 	[BPF_SK_MSG_VERDICT]		= "sk_msg_verdict",
111 	[BPF_LIRC_MODE2]		= "lirc_mode2",
112 	[BPF_FLOW_DISSECTOR]		= "flow_dissector",
113 	[BPF_TRACE_RAW_TP]		= "trace_raw_tp",
114 	[BPF_TRACE_FENTRY]		= "trace_fentry",
115 	[BPF_TRACE_FEXIT]		= "trace_fexit",
116 	[BPF_MODIFY_RETURN]		= "modify_return",
117 	[BPF_LSM_MAC]			= "lsm_mac",
118 	[BPF_LSM_CGROUP]		= "lsm_cgroup",
119 	[BPF_SK_LOOKUP]			= "sk_lookup",
120 	[BPF_TRACE_ITER]		= "trace_iter",
121 	[BPF_XDP_DEVMAP]		= "xdp_devmap",
122 	[BPF_XDP_CPUMAP]		= "xdp_cpumap",
123 	[BPF_XDP]			= "xdp",
124 	[BPF_SK_REUSEPORT_SELECT]	= "sk_reuseport_select",
125 	[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE]	= "sk_reuseport_select_or_migrate",
126 	[BPF_PERF_EVENT]		= "perf_event",
127 	[BPF_TRACE_KPROBE_MULTI]	= "trace_kprobe_multi",
128 	[BPF_STRUCT_OPS]		= "struct_ops",
129 	[BPF_NETFILTER]			= "netfilter",
130 	[BPF_TCX_INGRESS]		= "tcx_ingress",
131 	[BPF_TCX_EGRESS]		= "tcx_egress",
132 	[BPF_TRACE_UPROBE_MULTI]	= "trace_uprobe_multi",
133 	[BPF_NETKIT_PRIMARY]		= "netkit_primary",
134 	[BPF_NETKIT_PEER]		= "netkit_peer",
135 	[BPF_TRACE_KPROBE_SESSION]	= "trace_kprobe_session",
136 	[BPF_TRACE_UPROBE_SESSION]	= "trace_uprobe_session",
137 };
138 
139 static const char * const link_type_name[] = {
140 	[BPF_LINK_TYPE_UNSPEC]			= "unspec",
141 	[BPF_LINK_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
142 	[BPF_LINK_TYPE_TRACING]			= "tracing",
143 	[BPF_LINK_TYPE_CGROUP]			= "cgroup",
144 	[BPF_LINK_TYPE_ITER]			= "iter",
145 	[BPF_LINK_TYPE_NETNS]			= "netns",
146 	[BPF_LINK_TYPE_XDP]			= "xdp",
147 	[BPF_LINK_TYPE_PERF_EVENT]		= "perf_event",
148 	[BPF_LINK_TYPE_KPROBE_MULTI]		= "kprobe_multi",
149 	[BPF_LINK_TYPE_STRUCT_OPS]		= "struct_ops",
150 	[BPF_LINK_TYPE_NETFILTER]		= "netfilter",
151 	[BPF_LINK_TYPE_TCX]			= "tcx",
152 	[BPF_LINK_TYPE_UPROBE_MULTI]		= "uprobe_multi",
153 	[BPF_LINK_TYPE_NETKIT]			= "netkit",
154 	[BPF_LINK_TYPE_SOCKMAP]			= "sockmap",
155 };
156 
157 static const char * const map_type_name[] = {
158 	[BPF_MAP_TYPE_UNSPEC]			= "unspec",
159 	[BPF_MAP_TYPE_HASH]			= "hash",
160 	[BPF_MAP_TYPE_ARRAY]			= "array",
161 	[BPF_MAP_TYPE_PROG_ARRAY]		= "prog_array",
162 	[BPF_MAP_TYPE_PERF_EVENT_ARRAY]		= "perf_event_array",
163 	[BPF_MAP_TYPE_PERCPU_HASH]		= "percpu_hash",
164 	[BPF_MAP_TYPE_PERCPU_ARRAY]		= "percpu_array",
165 	[BPF_MAP_TYPE_STACK_TRACE]		= "stack_trace",
166 	[BPF_MAP_TYPE_CGROUP_ARRAY]		= "cgroup_array",
167 	[BPF_MAP_TYPE_LRU_HASH]			= "lru_hash",
168 	[BPF_MAP_TYPE_LRU_PERCPU_HASH]		= "lru_percpu_hash",
169 	[BPF_MAP_TYPE_LPM_TRIE]			= "lpm_trie",
170 	[BPF_MAP_TYPE_ARRAY_OF_MAPS]		= "array_of_maps",
171 	[BPF_MAP_TYPE_HASH_OF_MAPS]		= "hash_of_maps",
172 	[BPF_MAP_TYPE_DEVMAP]			= "devmap",
173 	[BPF_MAP_TYPE_DEVMAP_HASH]		= "devmap_hash",
174 	[BPF_MAP_TYPE_SOCKMAP]			= "sockmap",
175 	[BPF_MAP_TYPE_CPUMAP]			= "cpumap",
176 	[BPF_MAP_TYPE_XSKMAP]			= "xskmap",
177 	[BPF_MAP_TYPE_SOCKHASH]			= "sockhash",
178 	[BPF_MAP_TYPE_CGROUP_STORAGE]		= "cgroup_storage",
179 	[BPF_MAP_TYPE_REUSEPORT_SOCKARRAY]	= "reuseport_sockarray",
180 	[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE]	= "percpu_cgroup_storage",
181 	[BPF_MAP_TYPE_QUEUE]			= "queue",
182 	[BPF_MAP_TYPE_STACK]			= "stack",
183 	[BPF_MAP_TYPE_SK_STORAGE]		= "sk_storage",
184 	[BPF_MAP_TYPE_STRUCT_OPS]		= "struct_ops",
185 	[BPF_MAP_TYPE_RINGBUF]			= "ringbuf",
186 	[BPF_MAP_TYPE_INODE_STORAGE]		= "inode_storage",
187 	[BPF_MAP_TYPE_TASK_STORAGE]		= "task_storage",
188 	[BPF_MAP_TYPE_BLOOM_FILTER]		= "bloom_filter",
189 	[BPF_MAP_TYPE_USER_RINGBUF]             = "user_ringbuf",
190 	[BPF_MAP_TYPE_CGRP_STORAGE]		= "cgrp_storage",
191 	[BPF_MAP_TYPE_ARENA]			= "arena",
192 };
193 
194 static const char * const prog_type_name[] = {
195 	[BPF_PROG_TYPE_UNSPEC]			= "unspec",
196 	[BPF_PROG_TYPE_SOCKET_FILTER]		= "socket_filter",
197 	[BPF_PROG_TYPE_KPROBE]			= "kprobe",
198 	[BPF_PROG_TYPE_SCHED_CLS]		= "sched_cls",
199 	[BPF_PROG_TYPE_SCHED_ACT]		= "sched_act",
200 	[BPF_PROG_TYPE_TRACEPOINT]		= "tracepoint",
201 	[BPF_PROG_TYPE_XDP]			= "xdp",
202 	[BPF_PROG_TYPE_PERF_EVENT]		= "perf_event",
203 	[BPF_PROG_TYPE_CGROUP_SKB]		= "cgroup_skb",
204 	[BPF_PROG_TYPE_CGROUP_SOCK]		= "cgroup_sock",
205 	[BPF_PROG_TYPE_LWT_IN]			= "lwt_in",
206 	[BPF_PROG_TYPE_LWT_OUT]			= "lwt_out",
207 	[BPF_PROG_TYPE_LWT_XMIT]		= "lwt_xmit",
208 	[BPF_PROG_TYPE_SOCK_OPS]		= "sock_ops",
209 	[BPF_PROG_TYPE_SK_SKB]			= "sk_skb",
210 	[BPF_PROG_TYPE_CGROUP_DEVICE]		= "cgroup_device",
211 	[BPF_PROG_TYPE_SK_MSG]			= "sk_msg",
212 	[BPF_PROG_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
213 	[BPF_PROG_TYPE_CGROUP_SOCK_ADDR]	= "cgroup_sock_addr",
214 	[BPF_PROG_TYPE_LWT_SEG6LOCAL]		= "lwt_seg6local",
215 	[BPF_PROG_TYPE_LIRC_MODE2]		= "lirc_mode2",
216 	[BPF_PROG_TYPE_SK_REUSEPORT]		= "sk_reuseport",
217 	[BPF_PROG_TYPE_FLOW_DISSECTOR]		= "flow_dissector",
218 	[BPF_PROG_TYPE_CGROUP_SYSCTL]		= "cgroup_sysctl",
219 	[BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE]	= "raw_tracepoint_writable",
220 	[BPF_PROG_TYPE_CGROUP_SOCKOPT]		= "cgroup_sockopt",
221 	[BPF_PROG_TYPE_TRACING]			= "tracing",
222 	[BPF_PROG_TYPE_STRUCT_OPS]		= "struct_ops",
223 	[BPF_PROG_TYPE_EXT]			= "ext",
224 	[BPF_PROG_TYPE_LSM]			= "lsm",
225 	[BPF_PROG_TYPE_SK_LOOKUP]		= "sk_lookup",
226 	[BPF_PROG_TYPE_SYSCALL]			= "syscall",
227 	[BPF_PROG_TYPE_NETFILTER]		= "netfilter",
228 };
229 
__base_pr(enum libbpf_print_level level,const char * format,va_list args)230 static int __base_pr(enum libbpf_print_level level, const char *format,
231 		     va_list args)
232 {
233 	const char *env_var = "LIBBPF_LOG_LEVEL";
234 	static enum libbpf_print_level min_level = LIBBPF_INFO;
235 	static bool initialized;
236 
237 	if (!initialized) {
238 		char *verbosity;
239 
240 		initialized = true;
241 		verbosity = getenv(env_var);
242 		if (verbosity) {
243 			if (strcasecmp(verbosity, "warn") == 0)
244 				min_level = LIBBPF_WARN;
245 			else if (strcasecmp(verbosity, "debug") == 0)
246 				min_level = LIBBPF_DEBUG;
247 			else if (strcasecmp(verbosity, "info") == 0)
248 				min_level = LIBBPF_INFO;
249 			else
250 				fprintf(stderr, "libbpf: unrecognized '%s' envvar value: '%s', should be one of 'warn', 'debug', or 'info'.\n",
251 					env_var, verbosity);
252 		}
253 	}
254 
255 	/* if too verbose, skip logging  */
256 	if (level > min_level)
257 		return 0;
258 
259 	return vfprintf(stderr, format, args);
260 }
261 
262 static libbpf_print_fn_t __libbpf_pr = __base_pr;
263 
libbpf_set_print(libbpf_print_fn_t fn)264 libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
265 {
266 	libbpf_print_fn_t old_print_fn;
267 
268 	old_print_fn = __atomic_exchange_n(&__libbpf_pr, fn, __ATOMIC_RELAXED);
269 
270 	return old_print_fn;
271 }
272 
273 __printf(2, 3)
libbpf_print(enum libbpf_print_level level,const char * format,...)274 void libbpf_print(enum libbpf_print_level level, const char *format, ...)
275 {
276 	va_list args;
277 	int old_errno;
278 	libbpf_print_fn_t print_fn;
279 
280 	print_fn = __atomic_load_n(&__libbpf_pr, __ATOMIC_RELAXED);
281 	if (!print_fn)
282 		return;
283 
284 	old_errno = errno;
285 
286 	va_start(args, format);
287 	__libbpf_pr(level, format, args);
288 	va_end(args);
289 
290 	errno = old_errno;
291 }
292 
pr_perm_msg(int err)293 static void pr_perm_msg(int err)
294 {
295 	struct rlimit limit;
296 	char buf[100];
297 
298 	if (err != -EPERM || geteuid() != 0)
299 		return;
300 
301 	err = getrlimit(RLIMIT_MEMLOCK, &limit);
302 	if (err)
303 		return;
304 
305 	if (limit.rlim_cur == RLIM_INFINITY)
306 		return;
307 
308 	if (limit.rlim_cur < 1024)
309 		snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
310 	else if (limit.rlim_cur < 1024*1024)
311 		snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
312 	else
313 		snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
314 
315 	pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
316 		buf);
317 }
318 
319 #define STRERR_BUFSIZE  128
320 
321 /* Copied from tools/perf/util/util.h */
322 #ifndef zfree
323 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
324 #endif
325 
326 #ifndef zclose
327 # define zclose(fd) ({			\
328 	int ___err = 0;			\
329 	if ((fd) >= 0)			\
330 		___err = close((fd));	\
331 	fd = -1;			\
332 	___err; })
333 #endif
334 
ptr_to_u64(const void * ptr)335 static inline __u64 ptr_to_u64(const void *ptr)
336 {
337 	return (__u64) (unsigned long) ptr;
338 }
339 
libbpf_set_strict_mode(enum libbpf_strict_mode mode)340 int libbpf_set_strict_mode(enum libbpf_strict_mode mode)
341 {
342 	/* as of v1.0 libbpf_set_strict_mode() is a no-op */
343 	return 0;
344 }
345 
libbpf_major_version(void)346 __u32 libbpf_major_version(void)
347 {
348 	return LIBBPF_MAJOR_VERSION;
349 }
350 
libbpf_minor_version(void)351 __u32 libbpf_minor_version(void)
352 {
353 	return LIBBPF_MINOR_VERSION;
354 }
355 
libbpf_version_string(void)356 const char *libbpf_version_string(void)
357 {
358 #define __S(X) #X
359 #define _S(X) __S(X)
360 	return  "v" _S(LIBBPF_MAJOR_VERSION) "." _S(LIBBPF_MINOR_VERSION);
361 #undef _S
362 #undef __S
363 }
364 
365 enum reloc_type {
366 	RELO_LD64,
367 	RELO_CALL,
368 	RELO_DATA,
369 	RELO_EXTERN_LD64,
370 	RELO_EXTERN_CALL,
371 	RELO_SUBPROG_ADDR,
372 	RELO_CORE,
373 };
374 
375 struct reloc_desc {
376 	enum reloc_type type;
377 	int insn_idx;
378 	union {
379 		const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
380 		struct {
381 			int map_idx;
382 			int sym_off;
383 			int ext_idx;
384 		};
385 	};
386 };
387 
388 /* stored as sec_def->cookie for all libbpf-supported SEC()s */
389 enum sec_def_flags {
390 	SEC_NONE = 0,
391 	/* expected_attach_type is optional, if kernel doesn't support that */
392 	SEC_EXP_ATTACH_OPT = 1,
393 	/* legacy, only used by libbpf_get_type_names() and
394 	 * libbpf_attach_type_by_name(), not used by libbpf itself at all.
395 	 * This used to be associated with cgroup (and few other) BPF programs
396 	 * that were attachable through BPF_PROG_ATTACH command. Pretty
397 	 * meaningless nowadays, though.
398 	 */
399 	SEC_ATTACHABLE = 2,
400 	SEC_ATTACHABLE_OPT = SEC_ATTACHABLE | SEC_EXP_ATTACH_OPT,
401 	/* attachment target is specified through BTF ID in either kernel or
402 	 * other BPF program's BTF object
403 	 */
404 	SEC_ATTACH_BTF = 4,
405 	/* BPF program type allows sleeping/blocking in kernel */
406 	SEC_SLEEPABLE = 8,
407 	/* BPF program support non-linear XDP buffer */
408 	SEC_XDP_FRAGS = 16,
409 	/* Setup proper attach type for usdt probes. */
410 	SEC_USDT = 32,
411 };
412 
413 struct bpf_sec_def {
414 	char *sec;
415 	enum bpf_prog_type prog_type;
416 	enum bpf_attach_type expected_attach_type;
417 	long cookie;
418 	int handler_id;
419 
420 	libbpf_prog_setup_fn_t prog_setup_fn;
421 	libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
422 	libbpf_prog_attach_fn_t prog_attach_fn;
423 };
424 
425 /*
426  * bpf_prog should be a better name but it has been used in
427  * linux/filter.h.
428  */
429 struct bpf_program {
430 	char *name;
431 	char *sec_name;
432 	size_t sec_idx;
433 	const struct bpf_sec_def *sec_def;
434 	/* this program's instruction offset (in number of instructions)
435 	 * within its containing ELF section
436 	 */
437 	size_t sec_insn_off;
438 	/* number of original instructions in ELF section belonging to this
439 	 * program, not taking into account subprogram instructions possible
440 	 * appended later during relocation
441 	 */
442 	size_t sec_insn_cnt;
443 	/* Offset (in number of instructions) of the start of instruction
444 	 * belonging to this BPF program  within its containing main BPF
445 	 * program. For the entry-point (main) BPF program, this is always
446 	 * zero. For a sub-program, this gets reset before each of main BPF
447 	 * programs are processed and relocated and is used to determined
448 	 * whether sub-program was already appended to the main program, and
449 	 * if yes, at which instruction offset.
450 	 */
451 	size_t sub_insn_off;
452 
453 	/* instructions that belong to BPF program; insns[0] is located at
454 	 * sec_insn_off instruction within its ELF section in ELF file, so
455 	 * when mapping ELF file instruction index to the local instruction,
456 	 * one needs to subtract sec_insn_off; and vice versa.
457 	 */
458 	struct bpf_insn *insns;
459 	/* actual number of instruction in this BPF program's image; for
460 	 * entry-point BPF programs this includes the size of main program
461 	 * itself plus all the used sub-programs, appended at the end
462 	 */
463 	size_t insns_cnt;
464 
465 	struct reloc_desc *reloc_desc;
466 	int nr_reloc;
467 
468 	/* BPF verifier log settings */
469 	char *log_buf;
470 	size_t log_size;
471 	__u32 log_level;
472 
473 	struct bpf_object *obj;
474 
475 	int fd;
476 	bool autoload;
477 	bool autoattach;
478 	bool sym_global;
479 	bool mark_btf_static;
480 	enum bpf_prog_type type;
481 	enum bpf_attach_type expected_attach_type;
482 	int exception_cb_idx;
483 
484 	int prog_ifindex;
485 	__u32 attach_btf_obj_fd;
486 	__u32 attach_btf_id;
487 	__u32 attach_prog_fd;
488 
489 	void *func_info;
490 	__u32 func_info_rec_size;
491 	__u32 func_info_cnt;
492 
493 	void *line_info;
494 	__u32 line_info_rec_size;
495 	__u32 line_info_cnt;
496 	__u32 prog_flags;
497 };
498 
499 struct bpf_struct_ops {
500 	struct bpf_program **progs;
501 	__u32 *kern_func_off;
502 	/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
503 	void *data;
504 	/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
505 	 *      btf_vmlinux's format.
506 	 * struct bpf_struct_ops_tcp_congestion_ops {
507 	 *	[... some other kernel fields ...]
508 	 *	struct tcp_congestion_ops data;
509 	 * }
510 	 * kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
511 	 * bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
512 	 * from "data".
513 	 */
514 	void *kern_vdata;
515 	__u32 type_id;
516 };
517 
518 #define DATA_SEC ".data"
519 #define BSS_SEC ".bss"
520 #define RODATA_SEC ".rodata"
521 #define KCONFIG_SEC ".kconfig"
522 #define KSYMS_SEC ".ksyms"
523 #define STRUCT_OPS_SEC ".struct_ops"
524 #define STRUCT_OPS_LINK_SEC ".struct_ops.link"
525 #define ARENA_SEC ".addr_space.1"
526 
527 enum libbpf_map_type {
528 	LIBBPF_MAP_UNSPEC,
529 	LIBBPF_MAP_DATA,
530 	LIBBPF_MAP_BSS,
531 	LIBBPF_MAP_RODATA,
532 	LIBBPF_MAP_KCONFIG,
533 };
534 
535 struct bpf_map_def {
536 	unsigned int type;
537 	unsigned int key_size;
538 	unsigned int value_size;
539 	unsigned int max_entries;
540 	unsigned int map_flags;
541 };
542 
543 struct bpf_map {
544 	struct bpf_object *obj;
545 	char *name;
546 	/* real_name is defined for special internal maps (.rodata*,
547 	 * .data*, .bss, .kconfig) and preserves their original ELF section
548 	 * name. This is important to be able to find corresponding BTF
549 	 * DATASEC information.
550 	 */
551 	char *real_name;
552 	int fd;
553 	int sec_idx;
554 	size_t sec_offset;
555 	int map_ifindex;
556 	int inner_map_fd;
557 	struct bpf_map_def def;
558 	__u32 numa_node;
559 	__u32 btf_var_idx;
560 	int mod_btf_fd;
561 	__u32 btf_key_type_id;
562 	__u32 btf_value_type_id;
563 	__u32 btf_vmlinux_value_type_id;
564 	enum libbpf_map_type libbpf_type;
565 	void *mmaped;
566 	struct bpf_struct_ops *st_ops;
567 	struct bpf_map *inner_map;
568 	void **init_slots;
569 	int init_slots_sz;
570 	char *pin_path;
571 	bool pinned;
572 	bool reused;
573 	bool autocreate;
574 	bool autoattach;
575 	__u64 map_extra;
576 };
577 
578 enum extern_type {
579 	EXT_UNKNOWN,
580 	EXT_KCFG,
581 	EXT_KSYM,
582 };
583 
584 enum kcfg_type {
585 	KCFG_UNKNOWN,
586 	KCFG_CHAR,
587 	KCFG_BOOL,
588 	KCFG_INT,
589 	KCFG_TRISTATE,
590 	KCFG_CHAR_ARR,
591 };
592 
593 struct extern_desc {
594 	enum extern_type type;
595 	int sym_idx;
596 	int btf_id;
597 	int sec_btf_id;
598 	const char *name;
599 	char *essent_name;
600 	bool is_set;
601 	bool is_weak;
602 	union {
603 		struct {
604 			enum kcfg_type type;
605 			int sz;
606 			int align;
607 			int data_off;
608 			bool is_signed;
609 		} kcfg;
610 		struct {
611 			unsigned long long addr;
612 
613 			/* target btf_id of the corresponding kernel var. */
614 			int kernel_btf_obj_fd;
615 			int kernel_btf_id;
616 
617 			/* local btf_id of the ksym extern's type. */
618 			__u32 type_id;
619 			/* BTF fd index to be patched in for insn->off, this is
620 			 * 0 for vmlinux BTF, index in obj->fd_array for module
621 			 * BTF
622 			 */
623 			__s16 btf_fd_idx;
624 		} ksym;
625 	};
626 };
627 
628 struct module_btf {
629 	struct btf *btf;
630 	char *name;
631 	__u32 id;
632 	int fd;
633 	int fd_array_idx;
634 };
635 
636 enum sec_type {
637 	SEC_UNUSED = 0,
638 	SEC_RELO,
639 	SEC_BSS,
640 	SEC_DATA,
641 	SEC_RODATA,
642 	SEC_ST_OPS,
643 };
644 
645 struct elf_sec_desc {
646 	enum sec_type sec_type;
647 	Elf64_Shdr *shdr;
648 	Elf_Data *data;
649 };
650 
651 struct elf_state {
652 	int fd;
653 	const void *obj_buf;
654 	size_t obj_buf_sz;
655 	Elf *elf;
656 	Elf64_Ehdr *ehdr;
657 	Elf_Data *symbols;
658 	Elf_Data *arena_data;
659 	size_t shstrndx; /* section index for section name strings */
660 	size_t strtabidx;
661 	struct elf_sec_desc *secs;
662 	size_t sec_cnt;
663 	int btf_maps_shndx;
664 	__u32 btf_maps_sec_btf_id;
665 	int text_shndx;
666 	int symbols_shndx;
667 	bool has_st_ops;
668 	int arena_data_shndx;
669 };
670 
671 struct usdt_manager;
672 
673 struct bpf_object {
674 	char name[BPF_OBJ_NAME_LEN];
675 	char license[64];
676 	__u32 kern_version;
677 
678 	struct bpf_program *programs;
679 	size_t nr_programs;
680 	struct bpf_map *maps;
681 	size_t nr_maps;
682 	size_t maps_cap;
683 
684 	char *kconfig;
685 	struct extern_desc *externs;
686 	int nr_extern;
687 	int kconfig_map_idx;
688 
689 	bool loaded;
690 	bool has_subcalls;
691 	bool has_rodata;
692 
693 	struct bpf_gen *gen_loader;
694 
695 	/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
696 	struct elf_state efile;
697 
698 	unsigned char byteorder;
699 
700 	struct btf *btf;
701 	struct btf_ext *btf_ext;
702 
703 	/* Parse and load BTF vmlinux if any of the programs in the object need
704 	 * it at load time.
705 	 */
706 	struct btf *btf_vmlinux;
707 	/* Path to the custom BTF to be used for BPF CO-RE relocations as an
708 	 * override for vmlinux BTF.
709 	 */
710 	char *btf_custom_path;
711 	/* vmlinux BTF override for CO-RE relocations */
712 	struct btf *btf_vmlinux_override;
713 	/* Lazily initialized kernel module BTFs */
714 	struct module_btf *btf_modules;
715 	bool btf_modules_loaded;
716 	size_t btf_module_cnt;
717 	size_t btf_module_cap;
718 
719 	/* optional log settings passed to BPF_BTF_LOAD and BPF_PROG_LOAD commands */
720 	char *log_buf;
721 	size_t log_size;
722 	__u32 log_level;
723 
724 	int *fd_array;
725 	size_t fd_array_cap;
726 	size_t fd_array_cnt;
727 
728 	struct usdt_manager *usdt_man;
729 
730 	struct bpf_map *arena_map;
731 	void *arena_data;
732 	size_t arena_data_sz;
733 
734 	struct kern_feature_cache *feat_cache;
735 	char *token_path;
736 	int token_fd;
737 
738 	char path[];
739 };
740 
741 static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
742 static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
743 static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
744 static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
745 static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
746 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
747 static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
748 static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
749 static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
750 
bpf_program__unload(struct bpf_program * prog)751 void bpf_program__unload(struct bpf_program *prog)
752 {
753 	if (!prog)
754 		return;
755 
756 	zclose(prog->fd);
757 
758 	zfree(&prog->func_info);
759 	zfree(&prog->line_info);
760 }
761 
bpf_program__exit(struct bpf_program * prog)762 static void bpf_program__exit(struct bpf_program *prog)
763 {
764 	if (!prog)
765 		return;
766 
767 	bpf_program__unload(prog);
768 	zfree(&prog->name);
769 	zfree(&prog->sec_name);
770 	zfree(&prog->insns);
771 	zfree(&prog->reloc_desc);
772 
773 	prog->nr_reloc = 0;
774 	prog->insns_cnt = 0;
775 	prog->sec_idx = -1;
776 }
777 
insn_is_subprog_call(const struct bpf_insn * insn)778 static bool insn_is_subprog_call(const struct bpf_insn *insn)
779 {
780 	return BPF_CLASS(insn->code) == BPF_JMP &&
781 	       BPF_OP(insn->code) == BPF_CALL &&
782 	       BPF_SRC(insn->code) == BPF_K &&
783 	       insn->src_reg == BPF_PSEUDO_CALL &&
784 	       insn->dst_reg == 0 &&
785 	       insn->off == 0;
786 }
787 
is_call_insn(const struct bpf_insn * insn)788 static bool is_call_insn(const struct bpf_insn *insn)
789 {
790 	return insn->code == (BPF_JMP | BPF_CALL);
791 }
792 
insn_is_pseudo_func(struct bpf_insn * insn)793 static bool insn_is_pseudo_func(struct bpf_insn *insn)
794 {
795 	return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
796 }
797 
798 static int
bpf_object__init_prog(struct bpf_object * obj,struct bpf_program * prog,const char * name,size_t sec_idx,const char * sec_name,size_t sec_off,void * insn_data,size_t insn_data_sz)799 bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
800 		      const char *name, size_t sec_idx, const char *sec_name,
801 		      size_t sec_off, void *insn_data, size_t insn_data_sz)
802 {
803 	if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
804 		pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
805 			sec_name, name, sec_off, insn_data_sz);
806 		return -EINVAL;
807 	}
808 
809 	memset(prog, 0, sizeof(*prog));
810 	prog->obj = obj;
811 
812 	prog->sec_idx = sec_idx;
813 	prog->sec_insn_off = sec_off / BPF_INSN_SZ;
814 	prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
815 	/* insns_cnt can later be increased by appending used subprograms */
816 	prog->insns_cnt = prog->sec_insn_cnt;
817 
818 	prog->type = BPF_PROG_TYPE_UNSPEC;
819 	prog->fd = -1;
820 	prog->exception_cb_idx = -1;
821 
822 	/* libbpf's convention for SEC("?abc...") is that it's just like
823 	 * SEC("abc...") but the corresponding bpf_program starts out with
824 	 * autoload set to false.
825 	 */
826 	if (sec_name[0] == '?') {
827 		prog->autoload = false;
828 		/* from now on forget there was ? in section name */
829 		sec_name++;
830 	} else {
831 		prog->autoload = true;
832 	}
833 
834 	prog->autoattach = true;
835 
836 	/* inherit object's log_level */
837 	prog->log_level = obj->log_level;
838 
839 	prog->sec_name = strdup(sec_name);
840 	if (!prog->sec_name)
841 		goto errout;
842 
843 	prog->name = strdup(name);
844 	if (!prog->name)
845 		goto errout;
846 
847 	prog->insns = malloc(insn_data_sz);
848 	if (!prog->insns)
849 		goto errout;
850 	memcpy(prog->insns, insn_data, insn_data_sz);
851 
852 	return 0;
853 errout:
854 	pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
855 	bpf_program__exit(prog);
856 	return -ENOMEM;
857 }
858 
859 static int
bpf_object__add_programs(struct bpf_object * obj,Elf_Data * sec_data,const char * sec_name,int sec_idx)860 bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
861 			 const char *sec_name, int sec_idx)
862 {
863 	Elf_Data *symbols = obj->efile.symbols;
864 	struct bpf_program *prog, *progs;
865 	void *data = sec_data->d_buf;
866 	size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
867 	int nr_progs, err, i;
868 	const char *name;
869 	Elf64_Sym *sym;
870 
871 	progs = obj->programs;
872 	nr_progs = obj->nr_programs;
873 	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
874 
875 	for (i = 0; i < nr_syms; i++) {
876 		sym = elf_sym_by_idx(obj, i);
877 
878 		if (sym->st_shndx != sec_idx)
879 			continue;
880 		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
881 			continue;
882 
883 		prog_sz = sym->st_size;
884 		sec_off = sym->st_value;
885 
886 		name = elf_sym_str(obj, sym->st_name);
887 		if (!name) {
888 			pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
889 				sec_name, sec_off);
890 			return -LIBBPF_ERRNO__FORMAT;
891 		}
892 
893 		if (sec_off + prog_sz > sec_sz) {
894 			pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
895 				sec_name, sec_off);
896 			return -LIBBPF_ERRNO__FORMAT;
897 		}
898 
899 		if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
900 			pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
901 			return -ENOTSUP;
902 		}
903 
904 		pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
905 			 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
906 
907 		progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
908 		if (!progs) {
909 			/*
910 			 * In this case the original obj->programs
911 			 * is still valid, so don't need special treat for
912 			 * bpf_close_object().
913 			 */
914 			pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
915 				sec_name, name);
916 			return -ENOMEM;
917 		}
918 		obj->programs = progs;
919 
920 		prog = &progs[nr_progs];
921 
922 		err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
923 					    sec_off, data + sec_off, prog_sz);
924 		if (err)
925 			return err;
926 
927 		if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL)
928 			prog->sym_global = true;
929 
930 		/* if function is a global/weak symbol, but has restricted
931 		 * (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF FUNC
932 		 * as static to enable more permissive BPF verification mode
933 		 * with more outside context available to BPF verifier
934 		 */
935 		if (prog->sym_global && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
936 		    || ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
937 			prog->mark_btf_static = true;
938 
939 		nr_progs++;
940 		obj->nr_programs = nr_progs;
941 	}
942 
943 	return 0;
944 }
945 
bpf_object_bswap_progs(struct bpf_object * obj)946 static void bpf_object_bswap_progs(struct bpf_object *obj)
947 {
948 	struct bpf_program *prog = obj->programs;
949 	struct bpf_insn *insn;
950 	int p, i;
951 
952 	for (p = 0; p < obj->nr_programs; p++, prog++) {
953 		insn = prog->insns;
954 		for (i = 0; i < prog->insns_cnt; i++, insn++)
955 			bpf_insn_bswap(insn);
956 	}
957 	pr_debug("converted %zu BPF programs to native byte order\n", obj->nr_programs);
958 }
959 
960 static const struct btf_member *
find_member_by_offset(const struct btf_type * t,__u32 bit_offset)961 find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
962 {
963 	struct btf_member *m;
964 	int i;
965 
966 	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
967 		if (btf_member_bit_offset(t, i) == bit_offset)
968 			return m;
969 	}
970 
971 	return NULL;
972 }
973 
974 static const struct btf_member *
find_member_by_name(const struct btf * btf,const struct btf_type * t,const char * name)975 find_member_by_name(const struct btf *btf, const struct btf_type *t,
976 		    const char *name)
977 {
978 	struct btf_member *m;
979 	int i;
980 
981 	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
982 		if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
983 			return m;
984 	}
985 
986 	return NULL;
987 }
988 
989 static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
990 			    __u16 kind, struct btf **res_btf,
991 			    struct module_btf **res_mod_btf);
992 
993 #define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
994 static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
995 				   const char *name, __u32 kind);
996 
997 static int
find_struct_ops_kern_types(struct bpf_object * obj,const char * tname_raw,struct module_btf ** mod_btf,const struct btf_type ** type,__u32 * type_id,const struct btf_type ** vtype,__u32 * vtype_id,const struct btf_member ** data_member)998 find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
999 			   struct module_btf **mod_btf,
1000 			   const struct btf_type **type, __u32 *type_id,
1001 			   const struct btf_type **vtype, __u32 *vtype_id,
1002 			   const struct btf_member **data_member)
1003 {
1004 	const struct btf_type *kern_type, *kern_vtype;
1005 	const struct btf_member *kern_data_member;
1006 	struct btf *btf = NULL;
1007 	__s32 kern_vtype_id, kern_type_id;
1008 	char tname[256];
1009 	__u32 i;
1010 
1011 	snprintf(tname, sizeof(tname), "%.*s",
1012 		 (int)bpf_core_essential_name_len(tname_raw), tname_raw);
1013 
1014 	kern_type_id = find_ksym_btf_id(obj, tname, BTF_KIND_STRUCT,
1015 					&btf, mod_btf);
1016 	if (kern_type_id < 0) {
1017 		pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
1018 			tname);
1019 		return kern_type_id;
1020 	}
1021 	kern_type = btf__type_by_id(btf, kern_type_id);
1022 
1023 	/* Find the corresponding "map_value" type that will be used
1024 	 * in map_update(BPF_MAP_TYPE_STRUCT_OPS).  For example,
1025 	 * find "struct bpf_struct_ops_tcp_congestion_ops" from the
1026 	 * btf_vmlinux.
1027 	 */
1028 	kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
1029 						tname, BTF_KIND_STRUCT);
1030 	if (kern_vtype_id < 0) {
1031 		pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
1032 			STRUCT_OPS_VALUE_PREFIX, tname);
1033 		return kern_vtype_id;
1034 	}
1035 	kern_vtype = btf__type_by_id(btf, kern_vtype_id);
1036 
1037 	/* Find "struct tcp_congestion_ops" from
1038 	 * struct bpf_struct_ops_tcp_congestion_ops {
1039 	 *	[ ... ]
1040 	 *	struct tcp_congestion_ops data;
1041 	 * }
1042 	 */
1043 	kern_data_member = btf_members(kern_vtype);
1044 	for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
1045 		if (kern_data_member->type == kern_type_id)
1046 			break;
1047 	}
1048 	if (i == btf_vlen(kern_vtype)) {
1049 		pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
1050 			tname, STRUCT_OPS_VALUE_PREFIX, tname);
1051 		return -EINVAL;
1052 	}
1053 
1054 	*type = kern_type;
1055 	*type_id = kern_type_id;
1056 	*vtype = kern_vtype;
1057 	*vtype_id = kern_vtype_id;
1058 	*data_member = kern_data_member;
1059 
1060 	return 0;
1061 }
1062 
bpf_map__is_struct_ops(const struct bpf_map * map)1063 static bool bpf_map__is_struct_ops(const struct bpf_map *map)
1064 {
1065 	return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
1066 }
1067 
is_valid_st_ops_program(struct bpf_object * obj,const struct bpf_program * prog)1068 static bool is_valid_st_ops_program(struct bpf_object *obj,
1069 				    const struct bpf_program *prog)
1070 {
1071 	int i;
1072 
1073 	for (i = 0; i < obj->nr_programs; i++) {
1074 		if (&obj->programs[i] == prog)
1075 			return prog->type == BPF_PROG_TYPE_STRUCT_OPS;
1076 	}
1077 
1078 	return false;
1079 }
1080 
1081 /* For each struct_ops program P, referenced from some struct_ops map M,
1082  * enable P.autoload if there are Ms for which M.autocreate is true,
1083  * disable P.autoload if for all Ms M.autocreate is false.
1084  * Don't change P.autoload for programs that are not referenced from any maps.
1085  */
bpf_object_adjust_struct_ops_autoload(struct bpf_object * obj)1086 static int bpf_object_adjust_struct_ops_autoload(struct bpf_object *obj)
1087 {
1088 	struct bpf_program *prog, *slot_prog;
1089 	struct bpf_map *map;
1090 	int i, j, k, vlen;
1091 
1092 	for (i = 0; i < obj->nr_programs; ++i) {
1093 		int should_load = false;
1094 		int use_cnt = 0;
1095 
1096 		prog = &obj->programs[i];
1097 		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
1098 			continue;
1099 
1100 		for (j = 0; j < obj->nr_maps; ++j) {
1101 			const struct btf_type *type;
1102 
1103 			map = &obj->maps[j];
1104 			if (!bpf_map__is_struct_ops(map))
1105 				continue;
1106 
1107 			type = btf__type_by_id(obj->btf, map->st_ops->type_id);
1108 			vlen = btf_vlen(type);
1109 			for (k = 0; k < vlen; ++k) {
1110 				slot_prog = map->st_ops->progs[k];
1111 				if (prog != slot_prog)
1112 					continue;
1113 
1114 				use_cnt++;
1115 				if (map->autocreate)
1116 					should_load = true;
1117 			}
1118 		}
1119 		if (use_cnt)
1120 			prog->autoload = should_load;
1121 	}
1122 
1123 	return 0;
1124 }
1125 
1126 /* Init the map's fields that depend on kern_btf */
bpf_map__init_kern_struct_ops(struct bpf_map * map)1127 static int bpf_map__init_kern_struct_ops(struct bpf_map *map)
1128 {
1129 	const struct btf_member *member, *kern_member, *kern_data_member;
1130 	const struct btf_type *type, *kern_type, *kern_vtype;
1131 	__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
1132 	struct bpf_object *obj = map->obj;
1133 	const struct btf *btf = obj->btf;
1134 	struct bpf_struct_ops *st_ops;
1135 	const struct btf *kern_btf;
1136 	struct module_btf *mod_btf = NULL;
1137 	void *data, *kern_data;
1138 	const char *tname;
1139 	int err;
1140 
1141 	st_ops = map->st_ops;
1142 	type = btf__type_by_id(btf, st_ops->type_id);
1143 	tname = btf__name_by_offset(btf, type->name_off);
1144 	err = find_struct_ops_kern_types(obj, tname, &mod_btf,
1145 					 &kern_type, &kern_type_id,
1146 					 &kern_vtype, &kern_vtype_id,
1147 					 &kern_data_member);
1148 	if (err)
1149 		return err;
1150 
1151 	kern_btf = mod_btf ? mod_btf->btf : obj->btf_vmlinux;
1152 
1153 	pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
1154 		 map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
1155 
1156 	map->mod_btf_fd = mod_btf ? mod_btf->fd : -1;
1157 	map->def.value_size = kern_vtype->size;
1158 	map->btf_vmlinux_value_type_id = kern_vtype_id;
1159 
1160 	st_ops->kern_vdata = calloc(1, kern_vtype->size);
1161 	if (!st_ops->kern_vdata)
1162 		return -ENOMEM;
1163 
1164 	data = st_ops->data;
1165 	kern_data_off = kern_data_member->offset / 8;
1166 	kern_data = st_ops->kern_vdata + kern_data_off;
1167 
1168 	member = btf_members(type);
1169 	for (i = 0; i < btf_vlen(type); i++, member++) {
1170 		const struct btf_type *mtype, *kern_mtype;
1171 		__u32 mtype_id, kern_mtype_id;
1172 		void *mdata, *kern_mdata;
1173 		struct bpf_program *prog;
1174 		__s64 msize, kern_msize;
1175 		__u32 moff, kern_moff;
1176 		__u32 kern_member_idx;
1177 		const char *mname;
1178 
1179 		mname = btf__name_by_offset(btf, member->name_off);
1180 		moff = member->offset / 8;
1181 		mdata = data + moff;
1182 		msize = btf__resolve_size(btf, member->type);
1183 		if (msize < 0) {
1184 			pr_warn("struct_ops init_kern %s: failed to resolve the size of member %s\n",
1185 				map->name, mname);
1186 			return msize;
1187 		}
1188 
1189 		kern_member = find_member_by_name(kern_btf, kern_type, mname);
1190 		if (!kern_member) {
1191 			if (!libbpf_is_mem_zeroed(mdata, msize)) {
1192 				pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
1193 					map->name, mname);
1194 				return -ENOTSUP;
1195 			}
1196 
1197 			if (st_ops->progs[i]) {
1198 				/* If we had declaratively set struct_ops callback, we need to
1199 				 * force its autoload to false, because it doesn't have
1200 				 * a chance of succeeding from POV of the current struct_ops map.
1201 				 * If this program is still referenced somewhere else, though,
1202 				 * then bpf_object_adjust_struct_ops_autoload() will update its
1203 				 * autoload accordingly.
1204 				 */
1205 				st_ops->progs[i]->autoload = false;
1206 				st_ops->progs[i] = NULL;
1207 			}
1208 
1209 			/* Skip all-zero/NULL fields if they are not present in the kernel BTF */
1210 			pr_info("struct_ops %s: member %s not found in kernel, skipping it as it's set to zero\n",
1211 				map->name, mname);
1212 			continue;
1213 		}
1214 
1215 		kern_member_idx = kern_member - btf_members(kern_type);
1216 		if (btf_member_bitfield_size(type, i) ||
1217 		    btf_member_bitfield_size(kern_type, kern_member_idx)) {
1218 			pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
1219 				map->name, mname);
1220 			return -ENOTSUP;
1221 		}
1222 
1223 		kern_moff = kern_member->offset / 8;
1224 		kern_mdata = kern_data + kern_moff;
1225 
1226 		mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
1227 		kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
1228 						    &kern_mtype_id);
1229 		if (BTF_INFO_KIND(mtype->info) !=
1230 		    BTF_INFO_KIND(kern_mtype->info)) {
1231 			pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
1232 				map->name, mname, BTF_INFO_KIND(mtype->info),
1233 				BTF_INFO_KIND(kern_mtype->info));
1234 			return -ENOTSUP;
1235 		}
1236 
1237 		if (btf_is_ptr(mtype)) {
1238 			prog = *(void **)mdata;
1239 			/* just like for !kern_member case above, reset declaratively
1240 			 * set (at compile time) program's autload to false,
1241 			 * if user replaced it with another program or NULL
1242 			 */
1243 			if (st_ops->progs[i] && st_ops->progs[i] != prog)
1244 				st_ops->progs[i]->autoload = false;
1245 
1246 			/* Update the value from the shadow type */
1247 			st_ops->progs[i] = prog;
1248 			if (!prog)
1249 				continue;
1250 
1251 			if (!is_valid_st_ops_program(obj, prog)) {
1252 				pr_warn("struct_ops init_kern %s: member %s is not a struct_ops program\n",
1253 					map->name, mname);
1254 				return -ENOTSUP;
1255 			}
1256 
1257 			kern_mtype = skip_mods_and_typedefs(kern_btf,
1258 							    kern_mtype->type,
1259 							    &kern_mtype_id);
1260 
1261 			/* mtype->type must be a func_proto which was
1262 			 * guaranteed in bpf_object__collect_st_ops_relos(),
1263 			 * so only check kern_mtype for func_proto here.
1264 			 */
1265 			if (!btf_is_func_proto(kern_mtype)) {
1266 				pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
1267 					map->name, mname);
1268 				return -ENOTSUP;
1269 			}
1270 
1271 			if (mod_btf)
1272 				prog->attach_btf_obj_fd = mod_btf->fd;
1273 
1274 			/* if we haven't yet processed this BPF program, record proper
1275 			 * attach_btf_id and member_idx
1276 			 */
1277 			if (!prog->attach_btf_id) {
1278 				prog->attach_btf_id = kern_type_id;
1279 				prog->expected_attach_type = kern_member_idx;
1280 			}
1281 
1282 			/* struct_ops BPF prog can be re-used between multiple
1283 			 * .struct_ops & .struct_ops.link as long as it's the
1284 			 * same struct_ops struct definition and the same
1285 			 * function pointer field
1286 			 */
1287 			if (prog->attach_btf_id != kern_type_id) {
1288 				pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: attach_btf_id %u != kern_type_id %u\n",
1289 					map->name, mname, prog->name, prog->sec_name, prog->type,
1290 					prog->attach_btf_id, kern_type_id);
1291 				return -EINVAL;
1292 			}
1293 			if (prog->expected_attach_type != kern_member_idx) {
1294 				pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: expected_attach_type %u != kern_member_idx %u\n",
1295 					map->name, mname, prog->name, prog->sec_name, prog->type,
1296 					prog->expected_attach_type, kern_member_idx);
1297 				return -EINVAL;
1298 			}
1299 
1300 			st_ops->kern_func_off[i] = kern_data_off + kern_moff;
1301 
1302 			pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
1303 				 map->name, mname, prog->name, moff,
1304 				 kern_moff);
1305 
1306 			continue;
1307 		}
1308 
1309 		kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
1310 		if (kern_msize < 0 || msize != kern_msize) {
1311 			pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
1312 				map->name, mname, (ssize_t)msize,
1313 				(ssize_t)kern_msize);
1314 			return -ENOTSUP;
1315 		}
1316 
1317 		pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
1318 			 map->name, mname, (unsigned int)msize,
1319 			 moff, kern_moff);
1320 		memcpy(kern_mdata, mdata, msize);
1321 	}
1322 
1323 	return 0;
1324 }
1325 
bpf_object__init_kern_struct_ops_maps(struct bpf_object * obj)1326 static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
1327 {
1328 	struct bpf_map *map;
1329 	size_t i;
1330 	int err;
1331 
1332 	for (i = 0; i < obj->nr_maps; i++) {
1333 		map = &obj->maps[i];
1334 
1335 		if (!bpf_map__is_struct_ops(map))
1336 			continue;
1337 
1338 		if (!map->autocreate)
1339 			continue;
1340 
1341 		err = bpf_map__init_kern_struct_ops(map);
1342 		if (err)
1343 			return err;
1344 	}
1345 
1346 	return 0;
1347 }
1348 
init_struct_ops_maps(struct bpf_object * obj,const char * sec_name,int shndx,Elf_Data * data)1349 static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
1350 				int shndx, Elf_Data *data)
1351 {
1352 	const struct btf_type *type, *datasec;
1353 	const struct btf_var_secinfo *vsi;
1354 	struct bpf_struct_ops *st_ops;
1355 	const char *tname, *var_name;
1356 	__s32 type_id, datasec_id;
1357 	const struct btf *btf;
1358 	struct bpf_map *map;
1359 	__u32 i;
1360 
1361 	if (shndx == -1)
1362 		return 0;
1363 
1364 	btf = obj->btf;
1365 	datasec_id = btf__find_by_name_kind(btf, sec_name,
1366 					    BTF_KIND_DATASEC);
1367 	if (datasec_id < 0) {
1368 		pr_warn("struct_ops init: DATASEC %s not found\n",
1369 			sec_name);
1370 		return -EINVAL;
1371 	}
1372 
1373 	datasec = btf__type_by_id(btf, datasec_id);
1374 	vsi = btf_var_secinfos(datasec);
1375 	for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
1376 		type = btf__type_by_id(obj->btf, vsi->type);
1377 		var_name = btf__name_by_offset(obj->btf, type->name_off);
1378 
1379 		type_id = btf__resolve_type(obj->btf, vsi->type);
1380 		if (type_id < 0) {
1381 			pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
1382 				vsi->type, sec_name);
1383 			return -EINVAL;
1384 		}
1385 
1386 		type = btf__type_by_id(obj->btf, type_id);
1387 		tname = btf__name_by_offset(obj->btf, type->name_off);
1388 		if (!tname[0]) {
1389 			pr_warn("struct_ops init: anonymous type is not supported\n");
1390 			return -ENOTSUP;
1391 		}
1392 		if (!btf_is_struct(type)) {
1393 			pr_warn("struct_ops init: %s is not a struct\n", tname);
1394 			return -EINVAL;
1395 		}
1396 
1397 		map = bpf_object__add_map(obj);
1398 		if (IS_ERR(map))
1399 			return PTR_ERR(map);
1400 
1401 		map->sec_idx = shndx;
1402 		map->sec_offset = vsi->offset;
1403 		map->name = strdup(var_name);
1404 		if (!map->name)
1405 			return -ENOMEM;
1406 		map->btf_value_type_id = type_id;
1407 
1408 		/* Follow same convention as for programs autoload:
1409 		 * SEC("?.struct_ops") means map is not created by default.
1410 		 */
1411 		if (sec_name[0] == '?') {
1412 			map->autocreate = false;
1413 			/* from now on forget there was ? in section name */
1414 			sec_name++;
1415 		}
1416 
1417 		map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
1418 		map->def.key_size = sizeof(int);
1419 		map->def.value_size = type->size;
1420 		map->def.max_entries = 1;
1421 		map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0 ? BPF_F_LINK : 0;
1422 		map->autoattach = true;
1423 
1424 		map->st_ops = calloc(1, sizeof(*map->st_ops));
1425 		if (!map->st_ops)
1426 			return -ENOMEM;
1427 		st_ops = map->st_ops;
1428 		st_ops->data = malloc(type->size);
1429 		st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
1430 		st_ops->kern_func_off = malloc(btf_vlen(type) *
1431 					       sizeof(*st_ops->kern_func_off));
1432 		if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
1433 			return -ENOMEM;
1434 
1435 		if (vsi->offset + type->size > data->d_size) {
1436 			pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
1437 				var_name, sec_name);
1438 			return -EINVAL;
1439 		}
1440 
1441 		memcpy(st_ops->data,
1442 		       data->d_buf + vsi->offset,
1443 		       type->size);
1444 		st_ops->type_id = type_id;
1445 
1446 		pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
1447 			 tname, type_id, var_name, vsi->offset);
1448 	}
1449 
1450 	return 0;
1451 }
1452 
bpf_object_init_struct_ops(struct bpf_object * obj)1453 static int bpf_object_init_struct_ops(struct bpf_object *obj)
1454 {
1455 	const char *sec_name;
1456 	int sec_idx, err;
1457 
1458 	for (sec_idx = 0; sec_idx < obj->efile.sec_cnt; ++sec_idx) {
1459 		struct elf_sec_desc *desc = &obj->efile.secs[sec_idx];
1460 
1461 		if (desc->sec_type != SEC_ST_OPS)
1462 			continue;
1463 
1464 		sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
1465 		if (!sec_name)
1466 			return -LIBBPF_ERRNO__FORMAT;
1467 
1468 		err = init_struct_ops_maps(obj, sec_name, sec_idx, desc->data);
1469 		if (err)
1470 			return err;
1471 	}
1472 
1473 	return 0;
1474 }
1475 
bpf_object__new(const char * path,const void * obj_buf,size_t obj_buf_sz,const char * obj_name)1476 static struct bpf_object *bpf_object__new(const char *path,
1477 					  const void *obj_buf,
1478 					  size_t obj_buf_sz,
1479 					  const char *obj_name)
1480 {
1481 	struct bpf_object *obj;
1482 	char *end;
1483 
1484 	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
1485 	if (!obj) {
1486 		pr_warn("alloc memory failed for %s\n", path);
1487 		return ERR_PTR(-ENOMEM);
1488 	}
1489 
1490 	strcpy(obj->path, path);
1491 	if (obj_name) {
1492 		libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name));
1493 	} else {
1494 		/* Using basename() GNU version which doesn't modify arg. */
1495 		libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name));
1496 		end = strchr(obj->name, '.');
1497 		if (end)
1498 			*end = 0;
1499 	}
1500 
1501 	obj->efile.fd = -1;
1502 	/*
1503 	 * Caller of this function should also call
1504 	 * bpf_object__elf_finish() after data collection to return
1505 	 * obj_buf to user. If not, we should duplicate the buffer to
1506 	 * avoid user freeing them before elf finish.
1507 	 */
1508 	obj->efile.obj_buf = obj_buf;
1509 	obj->efile.obj_buf_sz = obj_buf_sz;
1510 	obj->efile.btf_maps_shndx = -1;
1511 	obj->kconfig_map_idx = -1;
1512 
1513 	obj->kern_version = get_kernel_version();
1514 	obj->loaded = false;
1515 
1516 	return obj;
1517 }
1518 
bpf_object__elf_finish(struct bpf_object * obj)1519 static void bpf_object__elf_finish(struct bpf_object *obj)
1520 {
1521 	if (!obj->efile.elf)
1522 		return;
1523 
1524 	elf_end(obj->efile.elf);
1525 	obj->efile.elf = NULL;
1526 	obj->efile.ehdr = NULL;
1527 	obj->efile.symbols = NULL;
1528 	obj->efile.arena_data = NULL;
1529 
1530 	zfree(&obj->efile.secs);
1531 	obj->efile.sec_cnt = 0;
1532 	zclose(obj->efile.fd);
1533 	obj->efile.obj_buf = NULL;
1534 	obj->efile.obj_buf_sz = 0;
1535 }
1536 
bpf_object__elf_init(struct bpf_object * obj)1537 static int bpf_object__elf_init(struct bpf_object *obj)
1538 {
1539 	Elf64_Ehdr *ehdr;
1540 	int err = 0;
1541 	Elf *elf;
1542 
1543 	if (obj->efile.elf) {
1544 		pr_warn("elf: init internal error\n");
1545 		return -LIBBPF_ERRNO__LIBELF;
1546 	}
1547 
1548 	if (obj->efile.obj_buf_sz > 0) {
1549 		/* obj_buf should have been validated by bpf_object__open_mem(). */
1550 		elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
1551 	} else {
1552 		obj->efile.fd = open(obj->path, O_RDONLY | O_CLOEXEC);
1553 		if (obj->efile.fd < 0) {
1554 			err = -errno;
1555 			pr_warn("elf: failed to open %s: %s\n", obj->path, errstr(err));
1556 			return err;
1557 		}
1558 
1559 		elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
1560 	}
1561 
1562 	if (!elf) {
1563 		pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
1564 		err = -LIBBPF_ERRNO__LIBELF;
1565 		goto errout;
1566 	}
1567 
1568 	obj->efile.elf = elf;
1569 
1570 	if (elf_kind(elf) != ELF_K_ELF) {
1571 		err = -LIBBPF_ERRNO__FORMAT;
1572 		pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
1573 		goto errout;
1574 	}
1575 
1576 	if (gelf_getclass(elf) != ELFCLASS64) {
1577 		err = -LIBBPF_ERRNO__FORMAT;
1578 		pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
1579 		goto errout;
1580 	}
1581 
1582 	obj->efile.ehdr = ehdr = elf64_getehdr(elf);
1583 	if (!obj->efile.ehdr) {
1584 		pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
1585 		err = -LIBBPF_ERRNO__FORMAT;
1586 		goto errout;
1587 	}
1588 
1589 	/* Validate ELF object endianness... */
1590 	if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
1591 	    ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
1592 		err = -LIBBPF_ERRNO__ENDIAN;
1593 		pr_warn("elf: '%s' has unknown byte order\n", obj->path);
1594 		goto errout;
1595 	}
1596 	/* and save after bpf_object_open() frees ELF data */
1597 	obj->byteorder = ehdr->e_ident[EI_DATA];
1598 
1599 	if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
1600 		pr_warn("elf: failed to get section names section index for %s: %s\n",
1601 			obj->path, elf_errmsg(-1));
1602 		err = -LIBBPF_ERRNO__FORMAT;
1603 		goto errout;
1604 	}
1605 
1606 	/* ELF is corrupted/truncated, avoid calling elf_strptr. */
1607 	if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
1608 		pr_warn("elf: failed to get section names strings from %s: %s\n",
1609 			obj->path, elf_errmsg(-1));
1610 		err = -LIBBPF_ERRNO__FORMAT;
1611 		goto errout;
1612 	}
1613 
1614 	/* Old LLVM set e_machine to EM_NONE */
1615 	if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
1616 		pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
1617 		err = -LIBBPF_ERRNO__FORMAT;
1618 		goto errout;
1619 	}
1620 
1621 	return 0;
1622 errout:
1623 	bpf_object__elf_finish(obj);
1624 	return err;
1625 }
1626 
is_native_endianness(struct bpf_object * obj)1627 static bool is_native_endianness(struct bpf_object *obj)
1628 {
1629 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1630 	return obj->byteorder == ELFDATA2LSB;
1631 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
1632 	return obj->byteorder == ELFDATA2MSB;
1633 #else
1634 # error "Unrecognized __BYTE_ORDER__"
1635 #endif
1636 }
1637 
1638 static int
bpf_object__init_license(struct bpf_object * obj,void * data,size_t size)1639 bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
1640 {
1641 	if (!data) {
1642 		pr_warn("invalid license section in %s\n", obj->path);
1643 		return -LIBBPF_ERRNO__FORMAT;
1644 	}
1645 	/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
1646 	 * go over allowed ELF data section buffer
1647 	 */
1648 	libbpf_strlcpy(obj->license, data, min(size + 1, sizeof(obj->license)));
1649 	pr_debug("license of %s is %s\n", obj->path, obj->license);
1650 	return 0;
1651 }
1652 
1653 static int
bpf_object__init_kversion(struct bpf_object * obj,void * data,size_t size)1654 bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
1655 {
1656 	__u32 kver;
1657 
1658 	if (!data || size != sizeof(kver)) {
1659 		pr_warn("invalid kver section in %s\n", obj->path);
1660 		return -LIBBPF_ERRNO__FORMAT;
1661 	}
1662 	memcpy(&kver, data, sizeof(kver));
1663 	obj->kern_version = kver;
1664 	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
1665 	return 0;
1666 }
1667 
bpf_map_type__is_map_in_map(enum bpf_map_type type)1668 static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
1669 {
1670 	if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
1671 	    type == BPF_MAP_TYPE_HASH_OF_MAPS)
1672 		return true;
1673 	return false;
1674 }
1675 
find_elf_sec_sz(const struct bpf_object * obj,const char * name,__u32 * size)1676 static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
1677 {
1678 	Elf_Data *data;
1679 	Elf_Scn *scn;
1680 
1681 	if (!name)
1682 		return -EINVAL;
1683 
1684 	scn = elf_sec_by_name(obj, name);
1685 	data = elf_sec_data(obj, scn);
1686 	if (data) {
1687 		*size = data->d_size;
1688 		return 0; /* found it */
1689 	}
1690 
1691 	return -ENOENT;
1692 }
1693 
find_elf_var_sym(const struct bpf_object * obj,const char * name)1694 static Elf64_Sym *find_elf_var_sym(const struct bpf_object *obj, const char *name)
1695 {
1696 	Elf_Data *symbols = obj->efile.symbols;
1697 	const char *sname;
1698 	size_t si;
1699 
1700 	for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
1701 		Elf64_Sym *sym = elf_sym_by_idx(obj, si);
1702 
1703 		if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
1704 			continue;
1705 
1706 		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
1707 		    ELF64_ST_BIND(sym->st_info) != STB_WEAK)
1708 			continue;
1709 
1710 		sname = elf_sym_str(obj, sym->st_name);
1711 		if (!sname) {
1712 			pr_warn("failed to get sym name string for var %s\n", name);
1713 			return ERR_PTR(-EIO);
1714 		}
1715 		if (strcmp(name, sname) == 0)
1716 			return sym;
1717 	}
1718 
1719 	return ERR_PTR(-ENOENT);
1720 }
1721 
1722 /* Some versions of Android don't provide memfd_create() in their libc
1723  * implementation, so avoid complications and just go straight to Linux
1724  * syscall.
1725  */
sys_memfd_create(const char * name,unsigned flags)1726 static int sys_memfd_create(const char *name, unsigned flags)
1727 {
1728 	return syscall(__NR_memfd_create, name, flags);
1729 }
1730 
1731 #ifndef MFD_CLOEXEC
1732 #define MFD_CLOEXEC 0x0001U
1733 #endif
1734 #ifndef MFD_NOEXEC_SEAL
1735 #define MFD_NOEXEC_SEAL 0x0008U
1736 #endif
1737 
create_placeholder_fd(void)1738 static int create_placeholder_fd(void)
1739 {
1740 	unsigned int flags = MFD_CLOEXEC | MFD_NOEXEC_SEAL;
1741 	const char *name = "libbpf-placeholder-fd";
1742 	int fd;
1743 
1744 	fd = ensure_good_fd(sys_memfd_create(name, flags));
1745 	if (fd >= 0)
1746 		return fd;
1747 	else if (errno != EINVAL)
1748 		return -errno;
1749 
1750 	/* Possibly running on kernel without MFD_NOEXEC_SEAL */
1751 	fd = ensure_good_fd(sys_memfd_create(name, flags & ~MFD_NOEXEC_SEAL));
1752 	if (fd < 0)
1753 		return -errno;
1754 	return fd;
1755 }
1756 
bpf_object__add_map(struct bpf_object * obj)1757 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
1758 {
1759 	struct bpf_map *map;
1760 	int err;
1761 
1762 	err = libbpf_ensure_mem((void **)&obj->maps, &obj->maps_cap,
1763 				sizeof(*obj->maps), obj->nr_maps + 1);
1764 	if (err)
1765 		return ERR_PTR(err);
1766 
1767 	map = &obj->maps[obj->nr_maps++];
1768 	map->obj = obj;
1769 	/* Preallocate map FD without actually creating BPF map just yet.
1770 	 * These map FD "placeholders" will be reused later without changing
1771 	 * FD value when map is actually created in the kernel.
1772 	 *
1773 	 * This is useful to be able to perform BPF program relocations
1774 	 * without having to create BPF maps before that step. This allows us
1775 	 * to finalize and load BTF very late in BPF object's loading phase,
1776 	 * right before BPF maps have to be created and BPF programs have to
1777 	 * be loaded. By having these map FD placeholders we can perform all
1778 	 * the sanitizations, relocations, and any other adjustments before we
1779 	 * start creating actual BPF kernel objects (BTF, maps, progs).
1780 	 */
1781 	map->fd = create_placeholder_fd();
1782 	if (map->fd < 0)
1783 		return ERR_PTR(map->fd);
1784 	map->inner_map_fd = -1;
1785 	map->autocreate = true;
1786 
1787 	return map;
1788 }
1789 
array_map_mmap_sz(unsigned int value_sz,unsigned int max_entries)1790 static size_t array_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
1791 {
1792 	const long page_sz = sysconf(_SC_PAGE_SIZE);
1793 	size_t map_sz;
1794 
1795 	map_sz = (size_t)roundup(value_sz, 8) * max_entries;
1796 	map_sz = roundup(map_sz, page_sz);
1797 	return map_sz;
1798 }
1799 
bpf_map_mmap_sz(const struct bpf_map * map)1800 static size_t bpf_map_mmap_sz(const struct bpf_map *map)
1801 {
1802 	const long page_sz = sysconf(_SC_PAGE_SIZE);
1803 
1804 	switch (map->def.type) {
1805 	case BPF_MAP_TYPE_ARRAY:
1806 		return array_map_mmap_sz(map->def.value_size, map->def.max_entries);
1807 	case BPF_MAP_TYPE_ARENA:
1808 		return page_sz * map->def.max_entries;
1809 	default:
1810 		return 0; /* not supported */
1811 	}
1812 }
1813 
bpf_map_mmap_resize(struct bpf_map * map,size_t old_sz,size_t new_sz)1814 static int bpf_map_mmap_resize(struct bpf_map *map, size_t old_sz, size_t new_sz)
1815 {
1816 	void *mmaped;
1817 
1818 	if (!map->mmaped)
1819 		return -EINVAL;
1820 
1821 	if (old_sz == new_sz)
1822 		return 0;
1823 
1824 	mmaped = mmap(NULL, new_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
1825 	if (mmaped == MAP_FAILED)
1826 		return -errno;
1827 
1828 	memcpy(mmaped, map->mmaped, min(old_sz, new_sz));
1829 	munmap(map->mmaped, old_sz);
1830 	map->mmaped = mmaped;
1831 	return 0;
1832 }
1833 
internal_map_name(struct bpf_object * obj,const char * real_name)1834 static char *internal_map_name(struct bpf_object *obj, const char *real_name)
1835 {
1836 	char map_name[BPF_OBJ_NAME_LEN], *p;
1837 	int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
1838 
1839 	/* This is one of the more confusing parts of libbpf for various
1840 	 * reasons, some of which are historical. The original idea for naming
1841 	 * internal names was to include as much of BPF object name prefix as
1842 	 * possible, so that it can be distinguished from similar internal
1843 	 * maps of a different BPF object.
1844 	 * As an example, let's say we have bpf_object named 'my_object_name'
1845 	 * and internal map corresponding to '.rodata' ELF section. The final
1846 	 * map name advertised to user and to the kernel will be
1847 	 * 'my_objec.rodata', taking first 8 characters of object name and
1848 	 * entire 7 characters of '.rodata'.
1849 	 * Somewhat confusingly, if internal map ELF section name is shorter
1850 	 * than 7 characters, e.g., '.bss', we still reserve 7 characters
1851 	 * for the suffix, even though we only have 4 actual characters, and
1852 	 * resulting map will be called 'my_objec.bss', not even using all 15
1853 	 * characters allowed by the kernel. Oh well, at least the truncated
1854 	 * object name is somewhat consistent in this case. But if the map
1855 	 * name is '.kconfig', we'll still have entirety of '.kconfig' added
1856 	 * (8 chars) and thus will be left with only first 7 characters of the
1857 	 * object name ('my_obje'). Happy guessing, user, that the final map
1858 	 * name will be "my_obje.kconfig".
1859 	 * Now, with libbpf starting to support arbitrarily named .rodata.*
1860 	 * and .data.* data sections, it's possible that ELF section name is
1861 	 * longer than allowed 15 chars, so we now need to be careful to take
1862 	 * only up to 15 first characters of ELF name, taking no BPF object
1863 	 * name characters at all. So '.rodata.abracadabra' will result in
1864 	 * '.rodata.abracad' kernel and user-visible name.
1865 	 * We need to keep this convoluted logic intact for .data, .bss and
1866 	 * .rodata maps, but for new custom .data.custom and .rodata.custom
1867 	 * maps we use their ELF names as is, not prepending bpf_object name
1868 	 * in front. We still need to truncate them to 15 characters for the
1869 	 * kernel. Full name can be recovered for such maps by using DATASEC
1870 	 * BTF type associated with such map's value type, though.
1871 	 */
1872 	if (sfx_len >= BPF_OBJ_NAME_LEN)
1873 		sfx_len = BPF_OBJ_NAME_LEN - 1;
1874 
1875 	/* if there are two or more dots in map name, it's a custom dot map */
1876 	if (strchr(real_name + 1, '.') != NULL)
1877 		pfx_len = 0;
1878 	else
1879 		pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
1880 
1881 	snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
1882 		 sfx_len, real_name);
1883 
1884 	/* sanities map name to characters allowed by kernel */
1885 	for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
1886 		if (!isalnum(*p) && *p != '_' && *p != '.')
1887 			*p = '_';
1888 
1889 	return strdup(map_name);
1890 }
1891 
1892 static int
1893 map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map);
1894 
1895 /* Internal BPF map is mmap()'able only if at least one of corresponding
1896  * DATASEC's VARs are to be exposed through BPF skeleton. I.e., it's a GLOBAL
1897  * variable and it's not marked as __hidden (which turns it into, effectively,
1898  * a STATIC variable).
1899  */
map_is_mmapable(struct bpf_object * obj,struct bpf_map * map)1900 static bool map_is_mmapable(struct bpf_object *obj, struct bpf_map *map)
1901 {
1902 	const struct btf_type *t, *vt;
1903 	struct btf_var_secinfo *vsi;
1904 	int i, n;
1905 
1906 	if (!map->btf_value_type_id)
1907 		return false;
1908 
1909 	t = btf__type_by_id(obj->btf, map->btf_value_type_id);
1910 	if (!btf_is_datasec(t))
1911 		return false;
1912 
1913 	vsi = btf_var_secinfos(t);
1914 	for (i = 0, n = btf_vlen(t); i < n; i++, vsi++) {
1915 		vt = btf__type_by_id(obj->btf, vsi->type);
1916 		if (!btf_is_var(vt))
1917 			continue;
1918 
1919 		if (btf_var(vt)->linkage != BTF_VAR_STATIC)
1920 			return true;
1921 	}
1922 
1923 	return false;
1924 }
1925 
1926 static int
bpf_object__init_internal_map(struct bpf_object * obj,enum libbpf_map_type type,const char * real_name,int sec_idx,void * data,size_t data_sz)1927 bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
1928 			      const char *real_name, int sec_idx, void *data, size_t data_sz)
1929 {
1930 	struct bpf_map_def *def;
1931 	struct bpf_map *map;
1932 	size_t mmap_sz;
1933 	int err;
1934 
1935 	map = bpf_object__add_map(obj);
1936 	if (IS_ERR(map))
1937 		return PTR_ERR(map);
1938 
1939 	map->libbpf_type = type;
1940 	map->sec_idx = sec_idx;
1941 	map->sec_offset = 0;
1942 	map->real_name = strdup(real_name);
1943 	map->name = internal_map_name(obj, real_name);
1944 	if (!map->real_name || !map->name) {
1945 		zfree(&map->real_name);
1946 		zfree(&map->name);
1947 		return -ENOMEM;
1948 	}
1949 
1950 	def = &map->def;
1951 	def->type = BPF_MAP_TYPE_ARRAY;
1952 	def->key_size = sizeof(int);
1953 	def->value_size = data_sz;
1954 	def->max_entries = 1;
1955 	def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
1956 		? BPF_F_RDONLY_PROG : 0;
1957 
1958 	/* failures are fine because of maps like .rodata.str1.1 */
1959 	(void) map_fill_btf_type_info(obj, map);
1960 
1961 	if (map_is_mmapable(obj, map))
1962 		def->map_flags |= BPF_F_MMAPABLE;
1963 
1964 	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
1965 		 map->name, map->sec_idx, map->sec_offset, def->map_flags);
1966 
1967 	mmap_sz = bpf_map_mmap_sz(map);
1968 	map->mmaped = mmap(NULL, mmap_sz, PROT_READ | PROT_WRITE,
1969 			   MAP_SHARED | MAP_ANONYMOUS, -1, 0);
1970 	if (map->mmaped == MAP_FAILED) {
1971 		err = -errno;
1972 		map->mmaped = NULL;
1973 		pr_warn("failed to alloc map '%s' content buffer: %s\n", map->name, errstr(err));
1974 		zfree(&map->real_name);
1975 		zfree(&map->name);
1976 		return err;
1977 	}
1978 
1979 	if (data)
1980 		memcpy(map->mmaped, data, data_sz);
1981 
1982 	pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
1983 	return 0;
1984 }
1985 
bpf_object__init_global_data_maps(struct bpf_object * obj)1986 static int bpf_object__init_global_data_maps(struct bpf_object *obj)
1987 {
1988 	struct elf_sec_desc *sec_desc;
1989 	const char *sec_name;
1990 	int err = 0, sec_idx;
1991 
1992 	/*
1993 	 * Populate obj->maps with libbpf internal maps.
1994 	 */
1995 	for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
1996 		sec_desc = &obj->efile.secs[sec_idx];
1997 
1998 		/* Skip recognized sections with size 0. */
1999 		if (!sec_desc->data || sec_desc->data->d_size == 0)
2000 			continue;
2001 
2002 		switch (sec_desc->sec_type) {
2003 		case SEC_DATA:
2004 			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
2005 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
2006 							    sec_name, sec_idx,
2007 							    sec_desc->data->d_buf,
2008 							    sec_desc->data->d_size);
2009 			break;
2010 		case SEC_RODATA:
2011 			obj->has_rodata = true;
2012 			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
2013 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
2014 							    sec_name, sec_idx,
2015 							    sec_desc->data->d_buf,
2016 							    sec_desc->data->d_size);
2017 			break;
2018 		case SEC_BSS:
2019 			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
2020 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
2021 							    sec_name, sec_idx,
2022 							    NULL,
2023 							    sec_desc->data->d_size);
2024 			break;
2025 		default:
2026 			/* skip */
2027 			break;
2028 		}
2029 		if (err)
2030 			return err;
2031 	}
2032 	return 0;
2033 }
2034 
2035 
find_extern_by_name(const struct bpf_object * obj,const void * name)2036 static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
2037 					       const void *name)
2038 {
2039 	int i;
2040 
2041 	for (i = 0; i < obj->nr_extern; i++) {
2042 		if (strcmp(obj->externs[i].name, name) == 0)
2043 			return &obj->externs[i];
2044 	}
2045 	return NULL;
2046 }
2047 
find_extern_by_name_with_len(const struct bpf_object * obj,const void * name,int len)2048 static struct extern_desc *find_extern_by_name_with_len(const struct bpf_object *obj,
2049 							const void *name, int len)
2050 {
2051 	const char *ext_name;
2052 	int i;
2053 
2054 	for (i = 0; i < obj->nr_extern; i++) {
2055 		ext_name = obj->externs[i].name;
2056 		if (strlen(ext_name) == len && strncmp(ext_name, name, len) == 0)
2057 			return &obj->externs[i];
2058 	}
2059 	return NULL;
2060 }
2061 
set_kcfg_value_tri(struct extern_desc * ext,void * ext_val,char value)2062 static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
2063 			      char value)
2064 {
2065 	switch (ext->kcfg.type) {
2066 	case KCFG_BOOL:
2067 		if (value == 'm') {
2068 			pr_warn("extern (kcfg) '%s': value '%c' implies tristate or char type\n",
2069 				ext->name, value);
2070 			return -EINVAL;
2071 		}
2072 		*(bool *)ext_val = value == 'y' ? true : false;
2073 		break;
2074 	case KCFG_TRISTATE:
2075 		if (value == 'y')
2076 			*(enum libbpf_tristate *)ext_val = TRI_YES;
2077 		else if (value == 'm')
2078 			*(enum libbpf_tristate *)ext_val = TRI_MODULE;
2079 		else /* value == 'n' */
2080 			*(enum libbpf_tristate *)ext_val = TRI_NO;
2081 		break;
2082 	case KCFG_CHAR:
2083 		*(char *)ext_val = value;
2084 		break;
2085 	case KCFG_UNKNOWN:
2086 	case KCFG_INT:
2087 	case KCFG_CHAR_ARR:
2088 	default:
2089 		pr_warn("extern (kcfg) '%s': value '%c' implies bool, tristate, or char type\n",
2090 			ext->name, value);
2091 		return -EINVAL;
2092 	}
2093 	ext->is_set = true;
2094 	return 0;
2095 }
2096 
set_kcfg_value_str(struct extern_desc * ext,char * ext_val,const char * value)2097 static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
2098 			      const char *value)
2099 {
2100 	size_t len;
2101 
2102 	if (ext->kcfg.type != KCFG_CHAR_ARR) {
2103 		pr_warn("extern (kcfg) '%s': value '%s' implies char array type\n",
2104 			ext->name, value);
2105 		return -EINVAL;
2106 	}
2107 
2108 	len = strlen(value);
2109 	if (value[len - 1] != '"') {
2110 		pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
2111 			ext->name, value);
2112 		return -EINVAL;
2113 	}
2114 
2115 	/* strip quotes */
2116 	len -= 2;
2117 	if (len >= ext->kcfg.sz) {
2118 		pr_warn("extern (kcfg) '%s': long string '%s' of (%zu bytes) truncated to %d bytes\n",
2119 			ext->name, value, len, ext->kcfg.sz - 1);
2120 		len = ext->kcfg.sz - 1;
2121 	}
2122 	memcpy(ext_val, value + 1, len);
2123 	ext_val[len] = '\0';
2124 	ext->is_set = true;
2125 	return 0;
2126 }
2127 
parse_u64(const char * value,__u64 * res)2128 static int parse_u64(const char *value, __u64 *res)
2129 {
2130 	char *value_end;
2131 	int err;
2132 
2133 	errno = 0;
2134 	*res = strtoull(value, &value_end, 0);
2135 	if (errno) {
2136 		err = -errno;
2137 		pr_warn("failed to parse '%s': %s\n", value, errstr(err));
2138 		return err;
2139 	}
2140 	if (*value_end) {
2141 		pr_warn("failed to parse '%s' as integer completely\n", value);
2142 		return -EINVAL;
2143 	}
2144 	return 0;
2145 }
2146 
is_kcfg_value_in_range(const struct extern_desc * ext,__u64 v)2147 static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
2148 {
2149 	int bit_sz = ext->kcfg.sz * 8;
2150 
2151 	if (ext->kcfg.sz == 8)
2152 		return true;
2153 
2154 	/* Validate that value stored in u64 fits in integer of `ext->sz`
2155 	 * bytes size without any loss of information. If the target integer
2156 	 * is signed, we rely on the following limits of integer type of
2157 	 * Y bits and subsequent transformation:
2158 	 *
2159 	 *     -2^(Y-1) <= X           <= 2^(Y-1) - 1
2160 	 *            0 <= X + 2^(Y-1) <= 2^Y - 1
2161 	 *            0 <= X + 2^(Y-1) <  2^Y
2162 	 *
2163 	 *  For unsigned target integer, check that all the (64 - Y) bits are
2164 	 *  zero.
2165 	 */
2166 	if (ext->kcfg.is_signed)
2167 		return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
2168 	else
2169 		return (v >> bit_sz) == 0;
2170 }
2171 
set_kcfg_value_num(struct extern_desc * ext,void * ext_val,__u64 value)2172 static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
2173 			      __u64 value)
2174 {
2175 	if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR &&
2176 	    ext->kcfg.type != KCFG_BOOL) {
2177 		pr_warn("extern (kcfg) '%s': value '%llu' implies integer, char, or boolean type\n",
2178 			ext->name, (unsigned long long)value);
2179 		return -EINVAL;
2180 	}
2181 	if (ext->kcfg.type == KCFG_BOOL && value > 1) {
2182 		pr_warn("extern (kcfg) '%s': value '%llu' isn't boolean compatible\n",
2183 			ext->name, (unsigned long long)value);
2184 		return -EINVAL;
2185 
2186 	}
2187 	if (!is_kcfg_value_in_range(ext, value)) {
2188 		pr_warn("extern (kcfg) '%s': value '%llu' doesn't fit in %d bytes\n",
2189 			ext->name, (unsigned long long)value, ext->kcfg.sz);
2190 		return -ERANGE;
2191 	}
2192 	switch (ext->kcfg.sz) {
2193 	case 1:
2194 		*(__u8 *)ext_val = value;
2195 		break;
2196 	case 2:
2197 		*(__u16 *)ext_val = value;
2198 		break;
2199 	case 4:
2200 		*(__u32 *)ext_val = value;
2201 		break;
2202 	case 8:
2203 		*(__u64 *)ext_val = value;
2204 		break;
2205 	default:
2206 		return -EINVAL;
2207 	}
2208 	ext->is_set = true;
2209 	return 0;
2210 }
2211 
bpf_object__process_kconfig_line(struct bpf_object * obj,char * buf,void * data)2212 static int bpf_object__process_kconfig_line(struct bpf_object *obj,
2213 					    char *buf, void *data)
2214 {
2215 	struct extern_desc *ext;
2216 	char *sep, *value;
2217 	int len, err = 0;
2218 	void *ext_val;
2219 	__u64 num;
2220 
2221 	if (!str_has_pfx(buf, "CONFIG_"))
2222 		return 0;
2223 
2224 	sep = strchr(buf, '=');
2225 	if (!sep) {
2226 		pr_warn("failed to parse '%s': no separator\n", buf);
2227 		return -EINVAL;
2228 	}
2229 
2230 	/* Trim ending '\n' */
2231 	len = strlen(buf);
2232 	if (buf[len - 1] == '\n')
2233 		buf[len - 1] = '\0';
2234 	/* Split on '=' and ensure that a value is present. */
2235 	*sep = '\0';
2236 	if (!sep[1]) {
2237 		*sep = '=';
2238 		pr_warn("failed to parse '%s': no value\n", buf);
2239 		return -EINVAL;
2240 	}
2241 
2242 	ext = find_extern_by_name(obj, buf);
2243 	if (!ext || ext->is_set)
2244 		return 0;
2245 
2246 	ext_val = data + ext->kcfg.data_off;
2247 	value = sep + 1;
2248 
2249 	switch (*value) {
2250 	case 'y': case 'n': case 'm':
2251 		err = set_kcfg_value_tri(ext, ext_val, *value);
2252 		break;
2253 	case '"':
2254 		err = set_kcfg_value_str(ext, ext_val, value);
2255 		break;
2256 	default:
2257 		/* assume integer */
2258 		err = parse_u64(value, &num);
2259 		if (err) {
2260 			pr_warn("extern (kcfg) '%s': value '%s' isn't a valid integer\n", ext->name, value);
2261 			return err;
2262 		}
2263 		if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
2264 			pr_warn("extern (kcfg) '%s': value '%s' implies integer type\n", ext->name, value);
2265 			return -EINVAL;
2266 		}
2267 		err = set_kcfg_value_num(ext, ext_val, num);
2268 		break;
2269 	}
2270 	if (err)
2271 		return err;
2272 	pr_debug("extern (kcfg) '%s': set to %s\n", ext->name, value);
2273 	return 0;
2274 }
2275 
bpf_object__read_kconfig_file(struct bpf_object * obj,void * data)2276 static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
2277 {
2278 	char buf[PATH_MAX];
2279 	struct utsname uts;
2280 	int len, err = 0;
2281 	gzFile file;
2282 
2283 	uname(&uts);
2284 	len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
2285 	if (len < 0)
2286 		return -EINVAL;
2287 	else if (len >= PATH_MAX)
2288 		return -ENAMETOOLONG;
2289 
2290 	/* gzopen also accepts uncompressed files. */
2291 	file = gzopen(buf, "re");
2292 	if (!file)
2293 		file = gzopen("/proc/config.gz", "re");
2294 
2295 	if (!file) {
2296 		pr_warn("failed to open system Kconfig\n");
2297 		return -ENOENT;
2298 	}
2299 
2300 	while (gzgets(file, buf, sizeof(buf))) {
2301 		err = bpf_object__process_kconfig_line(obj, buf, data);
2302 		if (err) {
2303 			pr_warn("error parsing system Kconfig line '%s': %s\n",
2304 				buf, errstr(err));
2305 			goto out;
2306 		}
2307 	}
2308 
2309 out:
2310 	gzclose(file);
2311 	return err;
2312 }
2313 
bpf_object__read_kconfig_mem(struct bpf_object * obj,const char * config,void * data)2314 static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
2315 					const char *config, void *data)
2316 {
2317 	char buf[PATH_MAX];
2318 	int err = 0;
2319 	FILE *file;
2320 
2321 	file = fmemopen((void *)config, strlen(config), "r");
2322 	if (!file) {
2323 		err = -errno;
2324 		pr_warn("failed to open in-memory Kconfig: %s\n", errstr(err));
2325 		return err;
2326 	}
2327 
2328 	while (fgets(buf, sizeof(buf), file)) {
2329 		err = bpf_object__process_kconfig_line(obj, buf, data);
2330 		if (err) {
2331 			pr_warn("error parsing in-memory Kconfig line '%s': %s\n",
2332 				buf, errstr(err));
2333 			break;
2334 		}
2335 	}
2336 
2337 	fclose(file);
2338 	return err;
2339 }
2340 
bpf_object__init_kconfig_map(struct bpf_object * obj)2341 static int bpf_object__init_kconfig_map(struct bpf_object *obj)
2342 {
2343 	struct extern_desc *last_ext = NULL, *ext;
2344 	size_t map_sz;
2345 	int i, err;
2346 
2347 	for (i = 0; i < obj->nr_extern; i++) {
2348 		ext = &obj->externs[i];
2349 		if (ext->type == EXT_KCFG)
2350 			last_ext = ext;
2351 	}
2352 
2353 	if (!last_ext)
2354 		return 0;
2355 
2356 	map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
2357 	err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
2358 					    ".kconfig", obj->efile.symbols_shndx,
2359 					    NULL, map_sz);
2360 	if (err)
2361 		return err;
2362 
2363 	obj->kconfig_map_idx = obj->nr_maps - 1;
2364 
2365 	return 0;
2366 }
2367 
2368 const struct btf_type *
skip_mods_and_typedefs(const struct btf * btf,__u32 id,__u32 * res_id)2369 skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
2370 {
2371 	const struct btf_type *t = btf__type_by_id(btf, id);
2372 
2373 	if (res_id)
2374 		*res_id = id;
2375 
2376 	while (btf_is_mod(t) || btf_is_typedef(t)) {
2377 		if (res_id)
2378 			*res_id = t->type;
2379 		t = btf__type_by_id(btf, t->type);
2380 	}
2381 
2382 	return t;
2383 }
2384 
2385 static const struct btf_type *
resolve_func_ptr(const struct btf * btf,__u32 id,__u32 * res_id)2386 resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
2387 {
2388 	const struct btf_type *t;
2389 
2390 	t = skip_mods_and_typedefs(btf, id, NULL);
2391 	if (!btf_is_ptr(t))
2392 		return NULL;
2393 
2394 	t = skip_mods_and_typedefs(btf, t->type, res_id);
2395 
2396 	return btf_is_func_proto(t) ? t : NULL;
2397 }
2398 
__btf_kind_str(__u16 kind)2399 static const char *__btf_kind_str(__u16 kind)
2400 {
2401 	switch (kind) {
2402 	case BTF_KIND_UNKN: return "void";
2403 	case BTF_KIND_INT: return "int";
2404 	case BTF_KIND_PTR: return "ptr";
2405 	case BTF_KIND_ARRAY: return "array";
2406 	case BTF_KIND_STRUCT: return "struct";
2407 	case BTF_KIND_UNION: return "union";
2408 	case BTF_KIND_ENUM: return "enum";
2409 	case BTF_KIND_FWD: return "fwd";
2410 	case BTF_KIND_TYPEDEF: return "typedef";
2411 	case BTF_KIND_VOLATILE: return "volatile";
2412 	case BTF_KIND_CONST: return "const";
2413 	case BTF_KIND_RESTRICT: return "restrict";
2414 	case BTF_KIND_FUNC: return "func";
2415 	case BTF_KIND_FUNC_PROTO: return "func_proto";
2416 	case BTF_KIND_VAR: return "var";
2417 	case BTF_KIND_DATASEC: return "datasec";
2418 	case BTF_KIND_FLOAT: return "float";
2419 	case BTF_KIND_DECL_TAG: return "decl_tag";
2420 	case BTF_KIND_TYPE_TAG: return "type_tag";
2421 	case BTF_KIND_ENUM64: return "enum64";
2422 	default: return "unknown";
2423 	}
2424 }
2425 
btf_kind_str(const struct btf_type * t)2426 const char *btf_kind_str(const struct btf_type *t)
2427 {
2428 	return __btf_kind_str(btf_kind(t));
2429 }
2430 
2431 /*
2432  * Fetch integer attribute of BTF map definition. Such attributes are
2433  * represented using a pointer to an array, in which dimensionality of array
2434  * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
2435  * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
2436  * type definition, while using only sizeof(void *) space in ELF data section.
2437  */
get_map_field_int(const char * map_name,const struct btf * btf,const struct btf_member * m,__u32 * res)2438 static bool get_map_field_int(const char *map_name, const struct btf *btf,
2439 			      const struct btf_member *m, __u32 *res)
2440 {
2441 	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
2442 	const char *name = btf__name_by_offset(btf, m->name_off);
2443 	const struct btf_array *arr_info;
2444 	const struct btf_type *arr_t;
2445 
2446 	if (!btf_is_ptr(t)) {
2447 		pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
2448 			map_name, name, btf_kind_str(t));
2449 		return false;
2450 	}
2451 
2452 	arr_t = btf__type_by_id(btf, t->type);
2453 	if (!arr_t) {
2454 		pr_warn("map '%s': attr '%s': type [%u] not found.\n",
2455 			map_name, name, t->type);
2456 		return false;
2457 	}
2458 	if (!btf_is_array(arr_t)) {
2459 		pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
2460 			map_name, name, btf_kind_str(arr_t));
2461 		return false;
2462 	}
2463 	arr_info = btf_array(arr_t);
2464 	*res = arr_info->nelems;
2465 	return true;
2466 }
2467 
get_map_field_long(const char * map_name,const struct btf * btf,const struct btf_member * m,__u64 * res)2468 static bool get_map_field_long(const char *map_name, const struct btf *btf,
2469 			       const struct btf_member *m, __u64 *res)
2470 {
2471 	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
2472 	const char *name = btf__name_by_offset(btf, m->name_off);
2473 
2474 	if (btf_is_ptr(t)) {
2475 		__u32 res32;
2476 		bool ret;
2477 
2478 		ret = get_map_field_int(map_name, btf, m, &res32);
2479 		if (ret)
2480 			*res = (__u64)res32;
2481 		return ret;
2482 	}
2483 
2484 	if (!btf_is_enum(t) && !btf_is_enum64(t)) {
2485 		pr_warn("map '%s': attr '%s': expected ENUM or ENUM64, got %s.\n",
2486 			map_name, name, btf_kind_str(t));
2487 		return false;
2488 	}
2489 
2490 	if (btf_vlen(t) != 1) {
2491 		pr_warn("map '%s': attr '%s': invalid __ulong\n",
2492 			map_name, name);
2493 		return false;
2494 	}
2495 
2496 	if (btf_is_enum(t)) {
2497 		const struct btf_enum *e = btf_enum(t);
2498 
2499 		*res = e->val;
2500 	} else {
2501 		const struct btf_enum64 *e = btf_enum64(t);
2502 
2503 		*res = btf_enum64_value(e);
2504 	}
2505 	return true;
2506 }
2507 
pathname_concat(char * buf,size_t buf_sz,const char * path,const char * name)2508 static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
2509 {
2510 	int len;
2511 
2512 	len = snprintf(buf, buf_sz, "%s/%s", path, name);
2513 	if (len < 0)
2514 		return -EINVAL;
2515 	if (len >= buf_sz)
2516 		return -ENAMETOOLONG;
2517 
2518 	return 0;
2519 }
2520 
build_map_pin_path(struct bpf_map * map,const char * path)2521 static int build_map_pin_path(struct bpf_map *map, const char *path)
2522 {
2523 	char buf[PATH_MAX];
2524 	int err;
2525 
2526 	if (!path)
2527 		path = BPF_FS_DEFAULT_PATH;
2528 
2529 	err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
2530 	if (err)
2531 		return err;
2532 
2533 	return bpf_map__set_pin_path(map, buf);
2534 }
2535 
2536 /* should match definition in bpf_helpers.h */
2537 enum libbpf_pin_type {
2538 	LIBBPF_PIN_NONE,
2539 	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
2540 	LIBBPF_PIN_BY_NAME,
2541 };
2542 
parse_btf_map_def(const char * map_name,struct btf * btf,const struct btf_type * def_t,bool strict,struct btf_map_def * map_def,struct btf_map_def * inner_def)2543 int parse_btf_map_def(const char *map_name, struct btf *btf,
2544 		      const struct btf_type *def_t, bool strict,
2545 		      struct btf_map_def *map_def, struct btf_map_def *inner_def)
2546 {
2547 	const struct btf_type *t;
2548 	const struct btf_member *m;
2549 	bool is_inner = inner_def == NULL;
2550 	int vlen, i;
2551 
2552 	vlen = btf_vlen(def_t);
2553 	m = btf_members(def_t);
2554 	for (i = 0; i < vlen; i++, m++) {
2555 		const char *name = btf__name_by_offset(btf, m->name_off);
2556 
2557 		if (!name) {
2558 			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
2559 			return -EINVAL;
2560 		}
2561 		if (strcmp(name, "type") == 0) {
2562 			if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
2563 				return -EINVAL;
2564 			map_def->parts |= MAP_DEF_MAP_TYPE;
2565 		} else if (strcmp(name, "max_entries") == 0) {
2566 			if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
2567 				return -EINVAL;
2568 			map_def->parts |= MAP_DEF_MAX_ENTRIES;
2569 		} else if (strcmp(name, "map_flags") == 0) {
2570 			if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
2571 				return -EINVAL;
2572 			map_def->parts |= MAP_DEF_MAP_FLAGS;
2573 		} else if (strcmp(name, "numa_node") == 0) {
2574 			if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
2575 				return -EINVAL;
2576 			map_def->parts |= MAP_DEF_NUMA_NODE;
2577 		} else if (strcmp(name, "key_size") == 0) {
2578 			__u32 sz;
2579 
2580 			if (!get_map_field_int(map_name, btf, m, &sz))
2581 				return -EINVAL;
2582 			if (map_def->key_size && map_def->key_size != sz) {
2583 				pr_warn("map '%s': conflicting key size %u != %u.\n",
2584 					map_name, map_def->key_size, sz);
2585 				return -EINVAL;
2586 			}
2587 			map_def->key_size = sz;
2588 			map_def->parts |= MAP_DEF_KEY_SIZE;
2589 		} else if (strcmp(name, "key") == 0) {
2590 			__s64 sz;
2591 
2592 			t = btf__type_by_id(btf, m->type);
2593 			if (!t) {
2594 				pr_warn("map '%s': key type [%d] not found.\n",
2595 					map_name, m->type);
2596 				return -EINVAL;
2597 			}
2598 			if (!btf_is_ptr(t)) {
2599 				pr_warn("map '%s': key spec is not PTR: %s.\n",
2600 					map_name, btf_kind_str(t));
2601 				return -EINVAL;
2602 			}
2603 			sz = btf__resolve_size(btf, t->type);
2604 			if (sz < 0) {
2605 				pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
2606 					map_name, t->type, (ssize_t)sz);
2607 				return sz;
2608 			}
2609 			if (map_def->key_size && map_def->key_size != sz) {
2610 				pr_warn("map '%s': conflicting key size %u != %zd.\n",
2611 					map_name, map_def->key_size, (ssize_t)sz);
2612 				return -EINVAL;
2613 			}
2614 			map_def->key_size = sz;
2615 			map_def->key_type_id = t->type;
2616 			map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
2617 		} else if (strcmp(name, "value_size") == 0) {
2618 			__u32 sz;
2619 
2620 			if (!get_map_field_int(map_name, btf, m, &sz))
2621 				return -EINVAL;
2622 			if (map_def->value_size && map_def->value_size != sz) {
2623 				pr_warn("map '%s': conflicting value size %u != %u.\n",
2624 					map_name, map_def->value_size, sz);
2625 				return -EINVAL;
2626 			}
2627 			map_def->value_size = sz;
2628 			map_def->parts |= MAP_DEF_VALUE_SIZE;
2629 		} else if (strcmp(name, "value") == 0) {
2630 			__s64 sz;
2631 
2632 			t = btf__type_by_id(btf, m->type);
2633 			if (!t) {
2634 				pr_warn("map '%s': value type [%d] not found.\n",
2635 					map_name, m->type);
2636 				return -EINVAL;
2637 			}
2638 			if (!btf_is_ptr(t)) {
2639 				pr_warn("map '%s': value spec is not PTR: %s.\n",
2640 					map_name, btf_kind_str(t));
2641 				return -EINVAL;
2642 			}
2643 			sz = btf__resolve_size(btf, t->type);
2644 			if (sz < 0) {
2645 				pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
2646 					map_name, t->type, (ssize_t)sz);
2647 				return sz;
2648 			}
2649 			if (map_def->value_size && map_def->value_size != sz) {
2650 				pr_warn("map '%s': conflicting value size %u != %zd.\n",
2651 					map_name, map_def->value_size, (ssize_t)sz);
2652 				return -EINVAL;
2653 			}
2654 			map_def->value_size = sz;
2655 			map_def->value_type_id = t->type;
2656 			map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
2657 		}
2658 		else if (strcmp(name, "values") == 0) {
2659 			bool is_map_in_map = bpf_map_type__is_map_in_map(map_def->map_type);
2660 			bool is_prog_array = map_def->map_type == BPF_MAP_TYPE_PROG_ARRAY;
2661 			const char *desc = is_map_in_map ? "map-in-map inner" : "prog-array value";
2662 			char inner_map_name[128];
2663 			int err;
2664 
2665 			if (is_inner) {
2666 				pr_warn("map '%s': multi-level inner maps not supported.\n",
2667 					map_name);
2668 				return -ENOTSUP;
2669 			}
2670 			if (i != vlen - 1) {
2671 				pr_warn("map '%s': '%s' member should be last.\n",
2672 					map_name, name);
2673 				return -EINVAL;
2674 			}
2675 			if (!is_map_in_map && !is_prog_array) {
2676 				pr_warn("map '%s': should be map-in-map or prog-array.\n",
2677 					map_name);
2678 				return -ENOTSUP;
2679 			}
2680 			if (map_def->value_size && map_def->value_size != 4) {
2681 				pr_warn("map '%s': conflicting value size %u != 4.\n",
2682 					map_name, map_def->value_size);
2683 				return -EINVAL;
2684 			}
2685 			map_def->value_size = 4;
2686 			t = btf__type_by_id(btf, m->type);
2687 			if (!t) {
2688 				pr_warn("map '%s': %s type [%d] not found.\n",
2689 					map_name, desc, m->type);
2690 				return -EINVAL;
2691 			}
2692 			if (!btf_is_array(t) || btf_array(t)->nelems) {
2693 				pr_warn("map '%s': %s spec is not a zero-sized array.\n",
2694 					map_name, desc);
2695 				return -EINVAL;
2696 			}
2697 			t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
2698 			if (!btf_is_ptr(t)) {
2699 				pr_warn("map '%s': %s def is of unexpected kind %s.\n",
2700 					map_name, desc, btf_kind_str(t));
2701 				return -EINVAL;
2702 			}
2703 			t = skip_mods_and_typedefs(btf, t->type, NULL);
2704 			if (is_prog_array) {
2705 				if (!btf_is_func_proto(t)) {
2706 					pr_warn("map '%s': prog-array value def is of unexpected kind %s.\n",
2707 						map_name, btf_kind_str(t));
2708 					return -EINVAL;
2709 				}
2710 				continue;
2711 			}
2712 			if (!btf_is_struct(t)) {
2713 				pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
2714 					map_name, btf_kind_str(t));
2715 				return -EINVAL;
2716 			}
2717 
2718 			snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
2719 			err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
2720 			if (err)
2721 				return err;
2722 
2723 			map_def->parts |= MAP_DEF_INNER_MAP;
2724 		} else if (strcmp(name, "pinning") == 0) {
2725 			__u32 val;
2726 
2727 			if (is_inner) {
2728 				pr_warn("map '%s': inner def can't be pinned.\n", map_name);
2729 				return -EINVAL;
2730 			}
2731 			if (!get_map_field_int(map_name, btf, m, &val))
2732 				return -EINVAL;
2733 			if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
2734 				pr_warn("map '%s': invalid pinning value %u.\n",
2735 					map_name, val);
2736 				return -EINVAL;
2737 			}
2738 			map_def->pinning = val;
2739 			map_def->parts |= MAP_DEF_PINNING;
2740 		} else if (strcmp(name, "map_extra") == 0) {
2741 			__u64 map_extra;
2742 
2743 			if (!get_map_field_long(map_name, btf, m, &map_extra))
2744 				return -EINVAL;
2745 			map_def->map_extra = map_extra;
2746 			map_def->parts |= MAP_DEF_MAP_EXTRA;
2747 		} else {
2748 			if (strict) {
2749 				pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
2750 				return -ENOTSUP;
2751 			}
2752 			pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
2753 		}
2754 	}
2755 
2756 	if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
2757 		pr_warn("map '%s': map type isn't specified.\n", map_name);
2758 		return -EINVAL;
2759 	}
2760 
2761 	return 0;
2762 }
2763 
adjust_ringbuf_sz(size_t sz)2764 static size_t adjust_ringbuf_sz(size_t sz)
2765 {
2766 	__u32 page_sz = sysconf(_SC_PAGE_SIZE);
2767 	__u32 mul;
2768 
2769 	/* if user forgot to set any size, make sure they see error */
2770 	if (sz == 0)
2771 		return 0;
2772 	/* Kernel expects BPF_MAP_TYPE_RINGBUF's max_entries to be
2773 	 * a power-of-2 multiple of kernel's page size. If user diligently
2774 	 * satisified these conditions, pass the size through.
2775 	 */
2776 	if ((sz % page_sz) == 0 && is_pow_of_2(sz / page_sz))
2777 		return sz;
2778 
2779 	/* Otherwise find closest (page_sz * power_of_2) product bigger than
2780 	 * user-set size to satisfy both user size request and kernel
2781 	 * requirements and substitute correct max_entries for map creation.
2782 	 */
2783 	for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) {
2784 		if (mul * page_sz > sz)
2785 			return mul * page_sz;
2786 	}
2787 
2788 	/* if it's impossible to satisfy the conditions (i.e., user size is
2789 	 * very close to UINT_MAX but is not a power-of-2 multiple of
2790 	 * page_size) then just return original size and let kernel reject it
2791 	 */
2792 	return sz;
2793 }
2794 
map_is_ringbuf(const struct bpf_map * map)2795 static bool map_is_ringbuf(const struct bpf_map *map)
2796 {
2797 	return map->def.type == BPF_MAP_TYPE_RINGBUF ||
2798 	       map->def.type == BPF_MAP_TYPE_USER_RINGBUF;
2799 }
2800 
fill_map_from_def(struct bpf_map * map,const struct btf_map_def * def)2801 static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
2802 {
2803 	map->def.type = def->map_type;
2804 	map->def.key_size = def->key_size;
2805 	map->def.value_size = def->value_size;
2806 	map->def.max_entries = def->max_entries;
2807 	map->def.map_flags = def->map_flags;
2808 	map->map_extra = def->map_extra;
2809 
2810 	map->numa_node = def->numa_node;
2811 	map->btf_key_type_id = def->key_type_id;
2812 	map->btf_value_type_id = def->value_type_id;
2813 
2814 	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
2815 	if (map_is_ringbuf(map))
2816 		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
2817 
2818 	if (def->parts & MAP_DEF_MAP_TYPE)
2819 		pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
2820 
2821 	if (def->parts & MAP_DEF_KEY_TYPE)
2822 		pr_debug("map '%s': found key [%u], sz = %u.\n",
2823 			 map->name, def->key_type_id, def->key_size);
2824 	else if (def->parts & MAP_DEF_KEY_SIZE)
2825 		pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
2826 
2827 	if (def->parts & MAP_DEF_VALUE_TYPE)
2828 		pr_debug("map '%s': found value [%u], sz = %u.\n",
2829 			 map->name, def->value_type_id, def->value_size);
2830 	else if (def->parts & MAP_DEF_VALUE_SIZE)
2831 		pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
2832 
2833 	if (def->parts & MAP_DEF_MAX_ENTRIES)
2834 		pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
2835 	if (def->parts & MAP_DEF_MAP_FLAGS)
2836 		pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
2837 	if (def->parts & MAP_DEF_MAP_EXTRA)
2838 		pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
2839 			 (unsigned long long)def->map_extra);
2840 	if (def->parts & MAP_DEF_PINNING)
2841 		pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
2842 	if (def->parts & MAP_DEF_NUMA_NODE)
2843 		pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
2844 
2845 	if (def->parts & MAP_DEF_INNER_MAP)
2846 		pr_debug("map '%s': found inner map definition.\n", map->name);
2847 }
2848 
btf_var_linkage_str(__u32 linkage)2849 static const char *btf_var_linkage_str(__u32 linkage)
2850 {
2851 	switch (linkage) {
2852 	case BTF_VAR_STATIC: return "static";
2853 	case BTF_VAR_GLOBAL_ALLOCATED: return "global";
2854 	case BTF_VAR_GLOBAL_EXTERN: return "extern";
2855 	default: return "unknown";
2856 	}
2857 }
2858 
bpf_object__init_user_btf_map(struct bpf_object * obj,const struct btf_type * sec,int var_idx,int sec_idx,const Elf_Data * data,bool strict,const char * pin_root_path)2859 static int bpf_object__init_user_btf_map(struct bpf_object *obj,
2860 					 const struct btf_type *sec,
2861 					 int var_idx, int sec_idx,
2862 					 const Elf_Data *data, bool strict,
2863 					 const char *pin_root_path)
2864 {
2865 	struct btf_map_def map_def = {}, inner_def = {};
2866 	const struct btf_type *var, *def;
2867 	const struct btf_var_secinfo *vi;
2868 	const struct btf_var *var_extra;
2869 	const char *map_name;
2870 	struct bpf_map *map;
2871 	int err;
2872 
2873 	vi = btf_var_secinfos(sec) + var_idx;
2874 	var = btf__type_by_id(obj->btf, vi->type);
2875 	var_extra = btf_var(var);
2876 	map_name = btf__name_by_offset(obj->btf, var->name_off);
2877 
2878 	if (map_name == NULL || map_name[0] == '\0') {
2879 		pr_warn("map #%d: empty name.\n", var_idx);
2880 		return -EINVAL;
2881 	}
2882 	if ((__u64)vi->offset + vi->size > data->d_size) {
2883 		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
2884 		return -EINVAL;
2885 	}
2886 	if (!btf_is_var(var)) {
2887 		pr_warn("map '%s': unexpected var kind %s.\n",
2888 			map_name, btf_kind_str(var));
2889 		return -EINVAL;
2890 	}
2891 	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
2892 		pr_warn("map '%s': unsupported map linkage %s.\n",
2893 			map_name, btf_var_linkage_str(var_extra->linkage));
2894 		return -EOPNOTSUPP;
2895 	}
2896 
2897 	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
2898 	if (!btf_is_struct(def)) {
2899 		pr_warn("map '%s': unexpected def kind %s.\n",
2900 			map_name, btf_kind_str(var));
2901 		return -EINVAL;
2902 	}
2903 	if (def->size > vi->size) {
2904 		pr_warn("map '%s': invalid def size.\n", map_name);
2905 		return -EINVAL;
2906 	}
2907 
2908 	map = bpf_object__add_map(obj);
2909 	if (IS_ERR(map))
2910 		return PTR_ERR(map);
2911 	map->name = strdup(map_name);
2912 	if (!map->name) {
2913 		pr_warn("map '%s': failed to alloc map name.\n", map_name);
2914 		return -ENOMEM;
2915 	}
2916 	map->libbpf_type = LIBBPF_MAP_UNSPEC;
2917 	map->def.type = BPF_MAP_TYPE_UNSPEC;
2918 	map->sec_idx = sec_idx;
2919 	map->sec_offset = vi->offset;
2920 	map->btf_var_idx = var_idx;
2921 	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
2922 		 map_name, map->sec_idx, map->sec_offset);
2923 
2924 	err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
2925 	if (err)
2926 		return err;
2927 
2928 	fill_map_from_def(map, &map_def);
2929 
2930 	if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
2931 		err = build_map_pin_path(map, pin_root_path);
2932 		if (err) {
2933 			pr_warn("map '%s': couldn't build pin path.\n", map->name);
2934 			return err;
2935 		}
2936 	}
2937 
2938 	if (map_def.parts & MAP_DEF_INNER_MAP) {
2939 		map->inner_map = calloc(1, sizeof(*map->inner_map));
2940 		if (!map->inner_map)
2941 			return -ENOMEM;
2942 		map->inner_map->fd = create_placeholder_fd();
2943 		if (map->inner_map->fd < 0)
2944 			return map->inner_map->fd;
2945 		map->inner_map->sec_idx = sec_idx;
2946 		map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
2947 		if (!map->inner_map->name)
2948 			return -ENOMEM;
2949 		sprintf(map->inner_map->name, "%s.inner", map_name);
2950 
2951 		fill_map_from_def(map->inner_map, &inner_def);
2952 	}
2953 
2954 	err = map_fill_btf_type_info(obj, map);
2955 	if (err)
2956 		return err;
2957 
2958 	return 0;
2959 }
2960 
init_arena_map_data(struct bpf_object * obj,struct bpf_map * map,const char * sec_name,int sec_idx,void * data,size_t data_sz)2961 static int init_arena_map_data(struct bpf_object *obj, struct bpf_map *map,
2962 			       const char *sec_name, int sec_idx,
2963 			       void *data, size_t data_sz)
2964 {
2965 	const long page_sz = sysconf(_SC_PAGE_SIZE);
2966 	size_t mmap_sz;
2967 
2968 	mmap_sz = bpf_map_mmap_sz(obj->arena_map);
2969 	if (roundup(data_sz, page_sz) > mmap_sz) {
2970 		pr_warn("elf: sec '%s': declared ARENA map size (%zu) is too small to hold global __arena variables of size %zu\n",
2971 			sec_name, mmap_sz, data_sz);
2972 		return -E2BIG;
2973 	}
2974 
2975 	obj->arena_data = malloc(data_sz);
2976 	if (!obj->arena_data)
2977 		return -ENOMEM;
2978 	memcpy(obj->arena_data, data, data_sz);
2979 	obj->arena_data_sz = data_sz;
2980 
2981 	/* make bpf_map__init_value() work for ARENA maps */
2982 	map->mmaped = obj->arena_data;
2983 
2984 	return 0;
2985 }
2986 
bpf_object__init_user_btf_maps(struct bpf_object * obj,bool strict,const char * pin_root_path)2987 static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
2988 					  const char *pin_root_path)
2989 {
2990 	const struct btf_type *sec = NULL;
2991 	int nr_types, i, vlen, err;
2992 	const struct btf_type *t;
2993 	const char *name;
2994 	Elf_Data *data;
2995 	Elf_Scn *scn;
2996 
2997 	if (obj->efile.btf_maps_shndx < 0)
2998 		return 0;
2999 
3000 	scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
3001 	data = elf_sec_data(obj, scn);
3002 	if (!scn || !data) {
3003 		pr_warn("elf: failed to get %s map definitions for %s\n",
3004 			MAPS_ELF_SEC, obj->path);
3005 		return -EINVAL;
3006 	}
3007 
3008 	nr_types = btf__type_cnt(obj->btf);
3009 	for (i = 1; i < nr_types; i++) {
3010 		t = btf__type_by_id(obj->btf, i);
3011 		if (!btf_is_datasec(t))
3012 			continue;
3013 		name = btf__name_by_offset(obj->btf, t->name_off);
3014 		if (strcmp(name, MAPS_ELF_SEC) == 0) {
3015 			sec = t;
3016 			obj->efile.btf_maps_sec_btf_id = i;
3017 			break;
3018 		}
3019 	}
3020 
3021 	if (!sec) {
3022 		pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
3023 		return -ENOENT;
3024 	}
3025 
3026 	vlen = btf_vlen(sec);
3027 	for (i = 0; i < vlen; i++) {
3028 		err = bpf_object__init_user_btf_map(obj, sec, i,
3029 						    obj->efile.btf_maps_shndx,
3030 						    data, strict,
3031 						    pin_root_path);
3032 		if (err)
3033 			return err;
3034 	}
3035 
3036 	for (i = 0; i < obj->nr_maps; i++) {
3037 		struct bpf_map *map = &obj->maps[i];
3038 
3039 		if (map->def.type != BPF_MAP_TYPE_ARENA)
3040 			continue;
3041 
3042 		if (obj->arena_map) {
3043 			pr_warn("map '%s': only single ARENA map is supported (map '%s' is also ARENA)\n",
3044 				map->name, obj->arena_map->name);
3045 			return -EINVAL;
3046 		}
3047 		obj->arena_map = map;
3048 
3049 		if (obj->efile.arena_data) {
3050 			err = init_arena_map_data(obj, map, ARENA_SEC, obj->efile.arena_data_shndx,
3051 						  obj->efile.arena_data->d_buf,
3052 						  obj->efile.arena_data->d_size);
3053 			if (err)
3054 				return err;
3055 		}
3056 	}
3057 	if (obj->efile.arena_data && !obj->arena_map) {
3058 		pr_warn("elf: sec '%s': to use global __arena variables the ARENA map should be explicitly declared in SEC(\".maps\")\n",
3059 			ARENA_SEC);
3060 		return -ENOENT;
3061 	}
3062 
3063 	return 0;
3064 }
3065 
bpf_object__init_maps(struct bpf_object * obj,const struct bpf_object_open_opts * opts)3066 static int bpf_object__init_maps(struct bpf_object *obj,
3067 				 const struct bpf_object_open_opts *opts)
3068 {
3069 	const char *pin_root_path;
3070 	bool strict;
3071 	int err = 0;
3072 
3073 	strict = !OPTS_GET(opts, relaxed_maps, false);
3074 	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
3075 
3076 	err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
3077 	err = err ?: bpf_object__init_global_data_maps(obj);
3078 	err = err ?: bpf_object__init_kconfig_map(obj);
3079 	err = err ?: bpf_object_init_struct_ops(obj);
3080 
3081 	return err;
3082 }
3083 
section_have_execinstr(struct bpf_object * obj,int idx)3084 static bool section_have_execinstr(struct bpf_object *obj, int idx)
3085 {
3086 	Elf64_Shdr *sh;
3087 
3088 	sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
3089 	if (!sh)
3090 		return false;
3091 
3092 	return sh->sh_flags & SHF_EXECINSTR;
3093 }
3094 
starts_with_qmark(const char * s)3095 static bool starts_with_qmark(const char *s)
3096 {
3097 	return s && s[0] == '?';
3098 }
3099 
btf_needs_sanitization(struct bpf_object * obj)3100 static bool btf_needs_sanitization(struct bpf_object *obj)
3101 {
3102 	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
3103 	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
3104 	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
3105 	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
3106 	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
3107 	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
3108 	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
3109 	bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC);
3110 
3111 	return !has_func || !has_datasec || !has_func_global || !has_float ||
3112 	       !has_decl_tag || !has_type_tag || !has_enum64 || !has_qmark_datasec;
3113 }
3114 
bpf_object__sanitize_btf(struct bpf_object * obj,struct btf * btf)3115 static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
3116 {
3117 	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
3118 	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
3119 	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
3120 	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
3121 	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
3122 	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
3123 	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
3124 	bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC);
3125 	int enum64_placeholder_id = 0;
3126 	struct btf_type *t;
3127 	int i, j, vlen;
3128 
3129 	for (i = 1; i < btf__type_cnt(btf); i++) {
3130 		t = (struct btf_type *)btf__type_by_id(btf, i);
3131 
3132 		if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
3133 			/* replace VAR/DECL_TAG with INT */
3134 			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
3135 			/*
3136 			 * using size = 1 is the safest choice, 4 will be too
3137 			 * big and cause kernel BTF validation failure if
3138 			 * original variable took less than 4 bytes
3139 			 */
3140 			t->size = 1;
3141 			*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
3142 		} else if (!has_datasec && btf_is_datasec(t)) {
3143 			/* replace DATASEC with STRUCT */
3144 			const struct btf_var_secinfo *v = btf_var_secinfos(t);
3145 			struct btf_member *m = btf_members(t);
3146 			struct btf_type *vt;
3147 			char *name;
3148 
3149 			name = (char *)btf__name_by_offset(btf, t->name_off);
3150 			while (*name) {
3151 				if (*name == '.' || *name == '?')
3152 					*name = '_';
3153 				name++;
3154 			}
3155 
3156 			vlen = btf_vlen(t);
3157 			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
3158 			for (j = 0; j < vlen; j++, v++, m++) {
3159 				/* order of field assignments is important */
3160 				m->offset = v->offset * 8;
3161 				m->type = v->type;
3162 				/* preserve variable name as member name */
3163 				vt = (void *)btf__type_by_id(btf, v->type);
3164 				m->name_off = vt->name_off;
3165 			}
3166 		} else if (!has_qmark_datasec && btf_is_datasec(t) &&
3167 			   starts_with_qmark(btf__name_by_offset(btf, t->name_off))) {
3168 			/* replace '?' prefix with '_' for DATASEC names */
3169 			char *name;
3170 
3171 			name = (char *)btf__name_by_offset(btf, t->name_off);
3172 			if (name[0] == '?')
3173 				name[0] = '_';
3174 		} else if (!has_func && btf_is_func_proto(t)) {
3175 			/* replace FUNC_PROTO with ENUM */
3176 			vlen = btf_vlen(t);
3177 			t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
3178 			t->size = sizeof(__u32); /* kernel enforced */
3179 		} else if (!has_func && btf_is_func(t)) {
3180 			/* replace FUNC with TYPEDEF */
3181 			t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
3182 		} else if (!has_func_global && btf_is_func(t)) {
3183 			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
3184 			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
3185 		} else if (!has_float && btf_is_float(t)) {
3186 			/* replace FLOAT with an equally-sized empty STRUCT;
3187 			 * since C compilers do not accept e.g. "float" as a
3188 			 * valid struct name, make it anonymous
3189 			 */
3190 			t->name_off = 0;
3191 			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
3192 		} else if (!has_type_tag && btf_is_type_tag(t)) {
3193 			/* replace TYPE_TAG with a CONST */
3194 			t->name_off = 0;
3195 			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
3196 		} else if (!has_enum64 && btf_is_enum(t)) {
3197 			/* clear the kflag */
3198 			t->info = btf_type_info(btf_kind(t), btf_vlen(t), false);
3199 		} else if (!has_enum64 && btf_is_enum64(t)) {
3200 			/* replace ENUM64 with a union */
3201 			struct btf_member *m;
3202 
3203 			if (enum64_placeholder_id == 0) {
3204 				enum64_placeholder_id = btf__add_int(btf, "enum64_placeholder", 1, 0);
3205 				if (enum64_placeholder_id < 0)
3206 					return enum64_placeholder_id;
3207 
3208 				t = (struct btf_type *)btf__type_by_id(btf, i);
3209 			}
3210 
3211 			m = btf_members(t);
3212 			vlen = btf_vlen(t);
3213 			t->info = BTF_INFO_ENC(BTF_KIND_UNION, 0, vlen);
3214 			for (j = 0; j < vlen; j++, m++) {
3215 				m->type = enum64_placeholder_id;
3216 				m->offset = 0;
3217 			}
3218 		}
3219 	}
3220 
3221 	return 0;
3222 }
3223 
libbpf_needs_btf(const struct bpf_object * obj)3224 static bool libbpf_needs_btf(const struct bpf_object *obj)
3225 {
3226 	return obj->efile.btf_maps_shndx >= 0 ||
3227 	       obj->efile.has_st_ops ||
3228 	       obj->nr_extern > 0;
3229 }
3230 
kernel_needs_btf(const struct bpf_object * obj)3231 static bool kernel_needs_btf(const struct bpf_object *obj)
3232 {
3233 	return obj->efile.has_st_ops;
3234 }
3235 
bpf_object__init_btf(struct bpf_object * obj,Elf_Data * btf_data,Elf_Data * btf_ext_data)3236 static int bpf_object__init_btf(struct bpf_object *obj,
3237 				Elf_Data *btf_data,
3238 				Elf_Data *btf_ext_data)
3239 {
3240 	int err = -ENOENT;
3241 
3242 	if (btf_data) {
3243 		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
3244 		err = libbpf_get_error(obj->btf);
3245 		if (err) {
3246 			obj->btf = NULL;
3247 			pr_warn("Error loading ELF section %s: %s.\n", BTF_ELF_SEC, errstr(err));
3248 			goto out;
3249 		}
3250 		/* enforce 8-byte pointers for BPF-targeted BTFs */
3251 		btf__set_pointer_size(obj->btf, 8);
3252 	}
3253 	if (btf_ext_data) {
3254 		struct btf_ext_info *ext_segs[3];
3255 		int seg_num, sec_num;
3256 
3257 		if (!obj->btf) {
3258 			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
3259 				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
3260 			goto out;
3261 		}
3262 		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
3263 		err = libbpf_get_error(obj->btf_ext);
3264 		if (err) {
3265 			pr_warn("Error loading ELF section %s: %s. Ignored and continue.\n",
3266 				BTF_EXT_ELF_SEC, errstr(err));
3267 			obj->btf_ext = NULL;
3268 			goto out;
3269 		}
3270 
3271 		/* setup .BTF.ext to ELF section mapping */
3272 		ext_segs[0] = &obj->btf_ext->func_info;
3273 		ext_segs[1] = &obj->btf_ext->line_info;
3274 		ext_segs[2] = &obj->btf_ext->core_relo_info;
3275 		for (seg_num = 0; seg_num < ARRAY_SIZE(ext_segs); seg_num++) {
3276 			struct btf_ext_info *seg = ext_segs[seg_num];
3277 			const struct btf_ext_info_sec *sec;
3278 			const char *sec_name;
3279 			Elf_Scn *scn;
3280 
3281 			if (seg->sec_cnt == 0)
3282 				continue;
3283 
3284 			seg->sec_idxs = calloc(seg->sec_cnt, sizeof(*seg->sec_idxs));
3285 			if (!seg->sec_idxs) {
3286 				err = -ENOMEM;
3287 				goto out;
3288 			}
3289 
3290 			sec_num = 0;
3291 			for_each_btf_ext_sec(seg, sec) {
3292 				/* preventively increment index to avoid doing
3293 				 * this before every continue below
3294 				 */
3295 				sec_num++;
3296 
3297 				sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
3298 				if (str_is_empty(sec_name))
3299 					continue;
3300 				scn = elf_sec_by_name(obj, sec_name);
3301 				if (!scn)
3302 					continue;
3303 
3304 				seg->sec_idxs[sec_num - 1] = elf_ndxscn(scn);
3305 			}
3306 		}
3307 	}
3308 out:
3309 	if (err && libbpf_needs_btf(obj)) {
3310 		pr_warn("BTF is required, but is missing or corrupted.\n");
3311 		return err;
3312 	}
3313 	return 0;
3314 }
3315 
compare_vsi_off(const void * _a,const void * _b)3316 static int compare_vsi_off(const void *_a, const void *_b)
3317 {
3318 	const struct btf_var_secinfo *a = _a;
3319 	const struct btf_var_secinfo *b = _b;
3320 
3321 	return a->offset - b->offset;
3322 }
3323 
btf_fixup_datasec(struct bpf_object * obj,struct btf * btf,struct btf_type * t)3324 static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
3325 			     struct btf_type *t)
3326 {
3327 	__u32 size = 0, i, vars = btf_vlen(t);
3328 	const char *sec_name = btf__name_by_offset(btf, t->name_off);
3329 	struct btf_var_secinfo *vsi;
3330 	bool fixup_offsets = false;
3331 	int err;
3332 
3333 	if (!sec_name) {
3334 		pr_debug("No name found in string section for DATASEC kind.\n");
3335 		return -ENOENT;
3336 	}
3337 
3338 	/* Extern-backing datasecs (.ksyms, .kconfig) have their size and
3339 	 * variable offsets set at the previous step. Further, not every
3340 	 * extern BTF VAR has corresponding ELF symbol preserved, so we skip
3341 	 * all fixups altogether for such sections and go straight to sorting
3342 	 * VARs within their DATASEC.
3343 	 */
3344 	if (strcmp(sec_name, KCONFIG_SEC) == 0 || strcmp(sec_name, KSYMS_SEC) == 0)
3345 		goto sort_vars;
3346 
3347 	/* Clang leaves DATASEC size and VAR offsets as zeroes, so we need to
3348 	 * fix this up. But BPF static linker already fixes this up and fills
3349 	 * all the sizes and offsets during static linking. So this step has
3350 	 * to be optional. But the STV_HIDDEN handling is non-optional for any
3351 	 * non-extern DATASEC, so the variable fixup loop below handles both
3352 	 * functions at the same time, paying the cost of BTF VAR <-> ELF
3353 	 * symbol matching just once.
3354 	 */
3355 	if (t->size == 0) {
3356 		err = find_elf_sec_sz(obj, sec_name, &size);
3357 		if (err || !size) {
3358 			pr_debug("sec '%s': failed to determine size from ELF: size %u, err %s\n",
3359 				 sec_name, size, errstr(err));
3360 			return -ENOENT;
3361 		}
3362 
3363 		t->size = size;
3364 		fixup_offsets = true;
3365 	}
3366 
3367 	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
3368 		const struct btf_type *t_var;
3369 		struct btf_var *var;
3370 		const char *var_name;
3371 		Elf64_Sym *sym;
3372 
3373 		t_var = btf__type_by_id(btf, vsi->type);
3374 		if (!t_var || !btf_is_var(t_var)) {
3375 			pr_debug("sec '%s': unexpected non-VAR type found\n", sec_name);
3376 			return -EINVAL;
3377 		}
3378 
3379 		var = btf_var(t_var);
3380 		if (var->linkage == BTF_VAR_STATIC || var->linkage == BTF_VAR_GLOBAL_EXTERN)
3381 			continue;
3382 
3383 		var_name = btf__name_by_offset(btf, t_var->name_off);
3384 		if (!var_name) {
3385 			pr_debug("sec '%s': failed to find name of DATASEC's member #%d\n",
3386 				 sec_name, i);
3387 			return -ENOENT;
3388 		}
3389 
3390 		sym = find_elf_var_sym(obj, var_name);
3391 		if (IS_ERR(sym)) {
3392 			pr_debug("sec '%s': failed to find ELF symbol for VAR '%s'\n",
3393 				 sec_name, var_name);
3394 			return -ENOENT;
3395 		}
3396 
3397 		if (fixup_offsets)
3398 			vsi->offset = sym->st_value;
3399 
3400 		/* if variable is a global/weak symbol, but has restricted
3401 		 * (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF VAR
3402 		 * as static. This follows similar logic for functions (BPF
3403 		 * subprogs) and influences libbpf's further decisions about
3404 		 * whether to make global data BPF array maps as
3405 		 * BPF_F_MMAPABLE.
3406 		 */
3407 		if (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
3408 		    || ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL)
3409 			var->linkage = BTF_VAR_STATIC;
3410 	}
3411 
3412 sort_vars:
3413 	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
3414 	return 0;
3415 }
3416 
bpf_object_fixup_btf(struct bpf_object * obj)3417 static int bpf_object_fixup_btf(struct bpf_object *obj)
3418 {
3419 	int i, n, err = 0;
3420 
3421 	if (!obj->btf)
3422 		return 0;
3423 
3424 	n = btf__type_cnt(obj->btf);
3425 	for (i = 1; i < n; i++) {
3426 		struct btf_type *t = btf_type_by_id(obj->btf, i);
3427 
3428 		/* Loader needs to fix up some of the things compiler
3429 		 * couldn't get its hands on while emitting BTF. This
3430 		 * is section size and global variable offset. We use
3431 		 * the info from the ELF itself for this purpose.
3432 		 */
3433 		if (btf_is_datasec(t)) {
3434 			err = btf_fixup_datasec(obj, obj->btf, t);
3435 			if (err)
3436 				return err;
3437 		}
3438 	}
3439 
3440 	return 0;
3441 }
3442 
prog_needs_vmlinux_btf(struct bpf_program * prog)3443 static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
3444 {
3445 	if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
3446 	    prog->type == BPF_PROG_TYPE_LSM)
3447 		return true;
3448 
3449 	/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
3450 	 * also need vmlinux BTF
3451 	 */
3452 	if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
3453 		return true;
3454 
3455 	return false;
3456 }
3457 
map_needs_vmlinux_btf(struct bpf_map * map)3458 static bool map_needs_vmlinux_btf(struct bpf_map *map)
3459 {
3460 	return bpf_map__is_struct_ops(map);
3461 }
3462 
obj_needs_vmlinux_btf(const struct bpf_object * obj)3463 static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
3464 {
3465 	struct bpf_program *prog;
3466 	struct bpf_map *map;
3467 	int i;
3468 
3469 	/* CO-RE relocations need kernel BTF, only when btf_custom_path
3470 	 * is not specified
3471 	 */
3472 	if (obj->btf_ext && obj->btf_ext->core_relo_info.len && !obj->btf_custom_path)
3473 		return true;
3474 
3475 	/* Support for typed ksyms needs kernel BTF */
3476 	for (i = 0; i < obj->nr_extern; i++) {
3477 		const struct extern_desc *ext;
3478 
3479 		ext = &obj->externs[i];
3480 		if (ext->type == EXT_KSYM && ext->ksym.type_id)
3481 			return true;
3482 	}
3483 
3484 	bpf_object__for_each_program(prog, obj) {
3485 		if (!prog->autoload)
3486 			continue;
3487 		if (prog_needs_vmlinux_btf(prog))
3488 			return true;
3489 	}
3490 
3491 	bpf_object__for_each_map(map, obj) {
3492 		if (map_needs_vmlinux_btf(map))
3493 			return true;
3494 	}
3495 
3496 	return false;
3497 }
3498 
bpf_object__load_vmlinux_btf(struct bpf_object * obj,bool force)3499 static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
3500 {
3501 	int err;
3502 
3503 	/* btf_vmlinux could be loaded earlier */
3504 	if (obj->btf_vmlinux || obj->gen_loader)
3505 		return 0;
3506 
3507 	if (!force && !obj_needs_vmlinux_btf(obj))
3508 		return 0;
3509 
3510 	obj->btf_vmlinux = btf__load_vmlinux_btf();
3511 	err = libbpf_get_error(obj->btf_vmlinux);
3512 	if (err) {
3513 		pr_warn("Error loading vmlinux BTF: %s\n", errstr(err));
3514 		obj->btf_vmlinux = NULL;
3515 		return err;
3516 	}
3517 	return 0;
3518 }
3519 
bpf_object__sanitize_and_load_btf(struct bpf_object * obj)3520 static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
3521 {
3522 	struct btf *kern_btf = obj->btf;
3523 	bool btf_mandatory, sanitize;
3524 	int i, err = 0;
3525 
3526 	if (!obj->btf)
3527 		return 0;
3528 
3529 	if (!kernel_supports(obj, FEAT_BTF)) {
3530 		if (kernel_needs_btf(obj)) {
3531 			err = -EOPNOTSUPP;
3532 			goto report;
3533 		}
3534 		pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
3535 		return 0;
3536 	}
3537 
3538 	/* Even though some subprogs are global/weak, user might prefer more
3539 	 * permissive BPF verification process that BPF verifier performs for
3540 	 * static functions, taking into account more context from the caller
3541 	 * functions. In such case, they need to mark such subprogs with
3542 	 * __attribute__((visibility("hidden"))) and libbpf will adjust
3543 	 * corresponding FUNC BTF type to be marked as static and trigger more
3544 	 * involved BPF verification process.
3545 	 */
3546 	for (i = 0; i < obj->nr_programs; i++) {
3547 		struct bpf_program *prog = &obj->programs[i];
3548 		struct btf_type *t;
3549 		const char *name;
3550 		int j, n;
3551 
3552 		if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
3553 			continue;
3554 
3555 		n = btf__type_cnt(obj->btf);
3556 		for (j = 1; j < n; j++) {
3557 			t = btf_type_by_id(obj->btf, j);
3558 			if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
3559 				continue;
3560 
3561 			name = btf__str_by_offset(obj->btf, t->name_off);
3562 			if (strcmp(name, prog->name) != 0)
3563 				continue;
3564 
3565 			t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
3566 			break;
3567 		}
3568 	}
3569 
3570 	sanitize = btf_needs_sanitization(obj);
3571 	if (sanitize) {
3572 		const void *raw_data;
3573 		__u32 sz;
3574 
3575 		/* clone BTF to sanitize a copy and leave the original intact */
3576 		raw_data = btf__raw_data(obj->btf, &sz);
3577 		kern_btf = btf__new(raw_data, sz);
3578 		err = libbpf_get_error(kern_btf);
3579 		if (err)
3580 			return err;
3581 
3582 		/* enforce 8-byte pointers for BPF-targeted BTFs */
3583 		btf__set_pointer_size(obj->btf, 8);
3584 		err = bpf_object__sanitize_btf(obj, kern_btf);
3585 		if (err)
3586 			return err;
3587 	}
3588 
3589 	if (obj->gen_loader) {
3590 		__u32 raw_size = 0;
3591 		const void *raw_data = btf__raw_data(kern_btf, &raw_size);
3592 
3593 		if (!raw_data)
3594 			return -ENOMEM;
3595 		bpf_gen__load_btf(obj->gen_loader, raw_data, raw_size);
3596 		/* Pretend to have valid FD to pass various fd >= 0 checks.
3597 		 * This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
3598 		 */
3599 		btf__set_fd(kern_btf, 0);
3600 	} else {
3601 		/* currently BPF_BTF_LOAD only supports log_level 1 */
3602 		err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size,
3603 					   obj->log_level ? 1 : 0, obj->token_fd);
3604 	}
3605 	if (sanitize) {
3606 		if (!err) {
3607 			/* move fd to libbpf's BTF */
3608 			btf__set_fd(obj->btf, btf__fd(kern_btf));
3609 			btf__set_fd(kern_btf, -1);
3610 		}
3611 		btf__free(kern_btf);
3612 	}
3613 report:
3614 	if (err) {
3615 		btf_mandatory = kernel_needs_btf(obj);
3616 		if (btf_mandatory) {
3617 			pr_warn("Error loading .BTF into kernel: %s. BTF is mandatory, can't proceed.\n",
3618 				errstr(err));
3619 		} else {
3620 			pr_info("Error loading .BTF into kernel: %s. BTF is optional, ignoring.\n",
3621 				errstr(err));
3622 			err = 0;
3623 		}
3624 	}
3625 	return err;
3626 }
3627 
elf_sym_str(const struct bpf_object * obj,size_t off)3628 static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
3629 {
3630 	const char *name;
3631 
3632 	name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
3633 	if (!name) {
3634 		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
3635 			off, obj->path, elf_errmsg(-1));
3636 		return NULL;
3637 	}
3638 
3639 	return name;
3640 }
3641 
elf_sec_str(const struct bpf_object * obj,size_t off)3642 static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
3643 {
3644 	const char *name;
3645 
3646 	name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
3647 	if (!name) {
3648 		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
3649 			off, obj->path, elf_errmsg(-1));
3650 		return NULL;
3651 	}
3652 
3653 	return name;
3654 }
3655 
elf_sec_by_idx(const struct bpf_object * obj,size_t idx)3656 static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
3657 {
3658 	Elf_Scn *scn;
3659 
3660 	scn = elf_getscn(obj->efile.elf, idx);
3661 	if (!scn) {
3662 		pr_warn("elf: failed to get section(%zu) from %s: %s\n",
3663 			idx, obj->path, elf_errmsg(-1));
3664 		return NULL;
3665 	}
3666 	return scn;
3667 }
3668 
elf_sec_by_name(const struct bpf_object * obj,const char * name)3669 static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
3670 {
3671 	Elf_Scn *scn = NULL;
3672 	Elf *elf = obj->efile.elf;
3673 	const char *sec_name;
3674 
3675 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
3676 		sec_name = elf_sec_name(obj, scn);
3677 		if (!sec_name)
3678 			return NULL;
3679 
3680 		if (strcmp(sec_name, name) != 0)
3681 			continue;
3682 
3683 		return scn;
3684 	}
3685 	return NULL;
3686 }
3687 
elf_sec_hdr(const struct bpf_object * obj,Elf_Scn * scn)3688 static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
3689 {
3690 	Elf64_Shdr *shdr;
3691 
3692 	if (!scn)
3693 		return NULL;
3694 
3695 	shdr = elf64_getshdr(scn);
3696 	if (!shdr) {
3697 		pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
3698 			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
3699 		return NULL;
3700 	}
3701 
3702 	return shdr;
3703 }
3704 
elf_sec_name(const struct bpf_object * obj,Elf_Scn * scn)3705 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
3706 {
3707 	const char *name;
3708 	Elf64_Shdr *sh;
3709 
3710 	if (!scn)
3711 		return NULL;
3712 
3713 	sh = elf_sec_hdr(obj, scn);
3714 	if (!sh)
3715 		return NULL;
3716 
3717 	name = elf_sec_str(obj, sh->sh_name);
3718 	if (!name) {
3719 		pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
3720 			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
3721 		return NULL;
3722 	}
3723 
3724 	return name;
3725 }
3726 
elf_sec_data(const struct bpf_object * obj,Elf_Scn * scn)3727 static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
3728 {
3729 	Elf_Data *data;
3730 
3731 	if (!scn)
3732 		return NULL;
3733 
3734 	data = elf_getdata(scn, 0);
3735 	if (!data) {
3736 		pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
3737 			elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
3738 			obj->path, elf_errmsg(-1));
3739 		return NULL;
3740 	}
3741 
3742 	return data;
3743 }
3744 
elf_sym_by_idx(const struct bpf_object * obj,size_t idx)3745 static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
3746 {
3747 	if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
3748 		return NULL;
3749 
3750 	return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
3751 }
3752 
elf_rel_by_idx(Elf_Data * data,size_t idx)3753 static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
3754 {
3755 	if (idx >= data->d_size / sizeof(Elf64_Rel))
3756 		return NULL;
3757 
3758 	return (Elf64_Rel *)data->d_buf + idx;
3759 }
3760 
is_sec_name_dwarf(const char * name)3761 static bool is_sec_name_dwarf(const char *name)
3762 {
3763 	/* approximation, but the actual list is too long */
3764 	return str_has_pfx(name, ".debug_");
3765 }
3766 
ignore_elf_section(Elf64_Shdr * hdr,const char * name)3767 static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
3768 {
3769 	/* no special handling of .strtab */
3770 	if (hdr->sh_type == SHT_STRTAB)
3771 		return true;
3772 
3773 	/* ignore .llvm_addrsig section as well */
3774 	if (hdr->sh_type == SHT_LLVM_ADDRSIG)
3775 		return true;
3776 
3777 	/* no subprograms will lead to an empty .text section, ignore it */
3778 	if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
3779 	    strcmp(name, ".text") == 0)
3780 		return true;
3781 
3782 	/* DWARF sections */
3783 	if (is_sec_name_dwarf(name))
3784 		return true;
3785 
3786 	if (str_has_pfx(name, ".rel")) {
3787 		name += sizeof(".rel") - 1;
3788 		/* DWARF section relocations */
3789 		if (is_sec_name_dwarf(name))
3790 			return true;
3791 
3792 		/* .BTF and .BTF.ext don't need relocations */
3793 		if (strcmp(name, BTF_ELF_SEC) == 0 ||
3794 		    strcmp(name, BTF_EXT_ELF_SEC) == 0)
3795 			return true;
3796 	}
3797 
3798 	return false;
3799 }
3800 
cmp_progs(const void * _a,const void * _b)3801 static int cmp_progs(const void *_a, const void *_b)
3802 {
3803 	const struct bpf_program *a = _a;
3804 	const struct bpf_program *b = _b;
3805 
3806 	if (a->sec_idx != b->sec_idx)
3807 		return a->sec_idx < b->sec_idx ? -1 : 1;
3808 
3809 	/* sec_insn_off can't be the same within the section */
3810 	return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
3811 }
3812 
bpf_object__elf_collect(struct bpf_object * obj)3813 static int bpf_object__elf_collect(struct bpf_object *obj)
3814 {
3815 	struct elf_sec_desc *sec_desc;
3816 	Elf *elf = obj->efile.elf;
3817 	Elf_Data *btf_ext_data = NULL;
3818 	Elf_Data *btf_data = NULL;
3819 	int idx = 0, err = 0;
3820 	const char *name;
3821 	Elf_Data *data;
3822 	Elf_Scn *scn;
3823 	Elf64_Shdr *sh;
3824 
3825 	/* ELF section indices are 0-based, but sec #0 is special "invalid"
3826 	 * section. Since section count retrieved by elf_getshdrnum() does
3827 	 * include sec #0, it is already the necessary size of an array to keep
3828 	 * all the sections.
3829 	 */
3830 	if (elf_getshdrnum(obj->efile.elf, &obj->efile.sec_cnt)) {
3831 		pr_warn("elf: failed to get the number of sections for %s: %s\n",
3832 			obj->path, elf_errmsg(-1));
3833 		return -LIBBPF_ERRNO__FORMAT;
3834 	}
3835 	obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
3836 	if (!obj->efile.secs)
3837 		return -ENOMEM;
3838 
3839 	/* a bunch of ELF parsing functionality depends on processing symbols,
3840 	 * so do the first pass and find the symbol table
3841 	 */
3842 	scn = NULL;
3843 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
3844 		sh = elf_sec_hdr(obj, scn);
3845 		if (!sh)
3846 			return -LIBBPF_ERRNO__FORMAT;
3847 
3848 		if (sh->sh_type == SHT_SYMTAB) {
3849 			if (obj->efile.symbols) {
3850 				pr_warn("elf: multiple symbol tables in %s\n", obj->path);
3851 				return -LIBBPF_ERRNO__FORMAT;
3852 			}
3853 
3854 			data = elf_sec_data(obj, scn);
3855 			if (!data)
3856 				return -LIBBPF_ERRNO__FORMAT;
3857 
3858 			idx = elf_ndxscn(scn);
3859 
3860 			obj->efile.symbols = data;
3861 			obj->efile.symbols_shndx = idx;
3862 			obj->efile.strtabidx = sh->sh_link;
3863 		}
3864 	}
3865 
3866 	if (!obj->efile.symbols) {
3867 		pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
3868 			obj->path);
3869 		return -ENOENT;
3870 	}
3871 
3872 	scn = NULL;
3873 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
3874 		idx = elf_ndxscn(scn);
3875 		sec_desc = &obj->efile.secs[idx];
3876 
3877 		sh = elf_sec_hdr(obj, scn);
3878 		if (!sh)
3879 			return -LIBBPF_ERRNO__FORMAT;
3880 
3881 		name = elf_sec_str(obj, sh->sh_name);
3882 		if (!name)
3883 			return -LIBBPF_ERRNO__FORMAT;
3884 
3885 		if (ignore_elf_section(sh, name))
3886 			continue;
3887 
3888 		data = elf_sec_data(obj, scn);
3889 		if (!data)
3890 			return -LIBBPF_ERRNO__FORMAT;
3891 
3892 		pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
3893 			 idx, name, (unsigned long)data->d_size,
3894 			 (int)sh->sh_link, (unsigned long)sh->sh_flags,
3895 			 (int)sh->sh_type);
3896 
3897 		if (strcmp(name, "license") == 0) {
3898 			err = bpf_object__init_license(obj, data->d_buf, data->d_size);
3899 			if (err)
3900 				return err;
3901 		} else if (strcmp(name, "version") == 0) {
3902 			err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
3903 			if (err)
3904 				return err;
3905 		} else if (strcmp(name, "maps") == 0) {
3906 			pr_warn("elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+\n");
3907 			return -ENOTSUP;
3908 		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
3909 			obj->efile.btf_maps_shndx = idx;
3910 		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
3911 			if (sh->sh_type != SHT_PROGBITS)
3912 				return -LIBBPF_ERRNO__FORMAT;
3913 			btf_data = data;
3914 		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
3915 			if (sh->sh_type != SHT_PROGBITS)
3916 				return -LIBBPF_ERRNO__FORMAT;
3917 			btf_ext_data = data;
3918 		} else if (sh->sh_type == SHT_SYMTAB) {
3919 			/* already processed during the first pass above */
3920 		} else if (sh->sh_type == SHT_PROGBITS && data->d_size > 0) {
3921 			if (sh->sh_flags & SHF_EXECINSTR) {
3922 				if (strcmp(name, ".text") == 0)
3923 					obj->efile.text_shndx = idx;
3924 				err = bpf_object__add_programs(obj, data, name, idx);
3925 				if (err)
3926 					return err;
3927 			} else if (strcmp(name, DATA_SEC) == 0 ||
3928 				   str_has_pfx(name, DATA_SEC ".")) {
3929 				sec_desc->sec_type = SEC_DATA;
3930 				sec_desc->shdr = sh;
3931 				sec_desc->data = data;
3932 			} else if (strcmp(name, RODATA_SEC) == 0 ||
3933 				   str_has_pfx(name, RODATA_SEC ".")) {
3934 				sec_desc->sec_type = SEC_RODATA;
3935 				sec_desc->shdr = sh;
3936 				sec_desc->data = data;
3937 			} else if (strcmp(name, STRUCT_OPS_SEC) == 0 ||
3938 				   strcmp(name, STRUCT_OPS_LINK_SEC) == 0 ||
3939 				   strcmp(name, "?" STRUCT_OPS_SEC) == 0 ||
3940 				   strcmp(name, "?" STRUCT_OPS_LINK_SEC) == 0) {
3941 				sec_desc->sec_type = SEC_ST_OPS;
3942 				sec_desc->shdr = sh;
3943 				sec_desc->data = data;
3944 				obj->efile.has_st_ops = true;
3945 			} else if (strcmp(name, ARENA_SEC) == 0) {
3946 				obj->efile.arena_data = data;
3947 				obj->efile.arena_data_shndx = idx;
3948 			} else {
3949 				pr_info("elf: skipping unrecognized data section(%d) %s\n",
3950 					idx, name);
3951 			}
3952 		} else if (sh->sh_type == SHT_REL) {
3953 			int targ_sec_idx = sh->sh_info; /* points to other section */
3954 
3955 			if (sh->sh_entsize != sizeof(Elf64_Rel) ||
3956 			    targ_sec_idx >= obj->efile.sec_cnt)
3957 				return -LIBBPF_ERRNO__FORMAT;
3958 
3959 			/* Only do relo for section with exec instructions */
3960 			if (!section_have_execinstr(obj, targ_sec_idx) &&
3961 			    strcmp(name, ".rel" STRUCT_OPS_SEC) &&
3962 			    strcmp(name, ".rel" STRUCT_OPS_LINK_SEC) &&
3963 			    strcmp(name, ".rel?" STRUCT_OPS_SEC) &&
3964 			    strcmp(name, ".rel?" STRUCT_OPS_LINK_SEC) &&
3965 			    strcmp(name, ".rel" MAPS_ELF_SEC)) {
3966 				pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
3967 					idx, name, targ_sec_idx,
3968 					elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
3969 				continue;
3970 			}
3971 
3972 			sec_desc->sec_type = SEC_RELO;
3973 			sec_desc->shdr = sh;
3974 			sec_desc->data = data;
3975 		} else if (sh->sh_type == SHT_NOBITS && (strcmp(name, BSS_SEC) == 0 ||
3976 							 str_has_pfx(name, BSS_SEC "."))) {
3977 			sec_desc->sec_type = SEC_BSS;
3978 			sec_desc->shdr = sh;
3979 			sec_desc->data = data;
3980 		} else {
3981 			pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
3982 				(size_t)sh->sh_size);
3983 		}
3984 	}
3985 
3986 	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
3987 		pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
3988 		return -LIBBPF_ERRNO__FORMAT;
3989 	}
3990 
3991 	/* change BPF program insns to native endianness for introspection */
3992 	if (!is_native_endianness(obj))
3993 		bpf_object_bswap_progs(obj);
3994 
3995 	/* sort BPF programs by section name and in-section instruction offset
3996 	 * for faster search
3997 	 */
3998 	if (obj->nr_programs)
3999 		qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
4000 
4001 	return bpf_object__init_btf(obj, btf_data, btf_ext_data);
4002 }
4003 
sym_is_extern(const Elf64_Sym * sym)4004 static bool sym_is_extern(const Elf64_Sym *sym)
4005 {
4006 	int bind = ELF64_ST_BIND(sym->st_info);
4007 	/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
4008 	return sym->st_shndx == SHN_UNDEF &&
4009 	       (bind == STB_GLOBAL || bind == STB_WEAK) &&
4010 	       ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
4011 }
4012 
sym_is_subprog(const Elf64_Sym * sym,int text_shndx)4013 static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
4014 {
4015 	int bind = ELF64_ST_BIND(sym->st_info);
4016 	int type = ELF64_ST_TYPE(sym->st_info);
4017 
4018 	/* in .text section */
4019 	if (sym->st_shndx != text_shndx)
4020 		return false;
4021 
4022 	/* local function */
4023 	if (bind == STB_LOCAL && type == STT_SECTION)
4024 		return true;
4025 
4026 	/* global function */
4027 	return (bind == STB_GLOBAL || bind == STB_WEAK) && type == STT_FUNC;
4028 }
4029 
find_extern_btf_id(const struct btf * btf,const char * ext_name)4030 static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
4031 {
4032 	const struct btf_type *t;
4033 	const char *tname;
4034 	int i, n;
4035 
4036 	if (!btf)
4037 		return -ESRCH;
4038 
4039 	n = btf__type_cnt(btf);
4040 	for (i = 1; i < n; i++) {
4041 		t = btf__type_by_id(btf, i);
4042 
4043 		if (!btf_is_var(t) && !btf_is_func(t))
4044 			continue;
4045 
4046 		tname = btf__name_by_offset(btf, t->name_off);
4047 		if (strcmp(tname, ext_name))
4048 			continue;
4049 
4050 		if (btf_is_var(t) &&
4051 		    btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
4052 			return -EINVAL;
4053 
4054 		if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
4055 			return -EINVAL;
4056 
4057 		return i;
4058 	}
4059 
4060 	return -ENOENT;
4061 }
4062 
find_extern_sec_btf_id(struct btf * btf,int ext_btf_id)4063 static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
4064 	const struct btf_var_secinfo *vs;
4065 	const struct btf_type *t;
4066 	int i, j, n;
4067 
4068 	if (!btf)
4069 		return -ESRCH;
4070 
4071 	n = btf__type_cnt(btf);
4072 	for (i = 1; i < n; i++) {
4073 		t = btf__type_by_id(btf, i);
4074 
4075 		if (!btf_is_datasec(t))
4076 			continue;
4077 
4078 		vs = btf_var_secinfos(t);
4079 		for (j = 0; j < btf_vlen(t); j++, vs++) {
4080 			if (vs->type == ext_btf_id)
4081 				return i;
4082 		}
4083 	}
4084 
4085 	return -ENOENT;
4086 }
4087 
find_kcfg_type(const struct btf * btf,int id,bool * is_signed)4088 static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
4089 				     bool *is_signed)
4090 {
4091 	const struct btf_type *t;
4092 	const char *name;
4093 
4094 	t = skip_mods_and_typedefs(btf, id, NULL);
4095 	name = btf__name_by_offset(btf, t->name_off);
4096 
4097 	if (is_signed)
4098 		*is_signed = false;
4099 	switch (btf_kind(t)) {
4100 	case BTF_KIND_INT: {
4101 		int enc = btf_int_encoding(t);
4102 
4103 		if (enc & BTF_INT_BOOL)
4104 			return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
4105 		if (is_signed)
4106 			*is_signed = enc & BTF_INT_SIGNED;
4107 		if (t->size == 1)
4108 			return KCFG_CHAR;
4109 		if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
4110 			return KCFG_UNKNOWN;
4111 		return KCFG_INT;
4112 	}
4113 	case BTF_KIND_ENUM:
4114 		if (t->size != 4)
4115 			return KCFG_UNKNOWN;
4116 		if (strcmp(name, "libbpf_tristate"))
4117 			return KCFG_UNKNOWN;
4118 		return KCFG_TRISTATE;
4119 	case BTF_KIND_ENUM64:
4120 		if (strcmp(name, "libbpf_tristate"))
4121 			return KCFG_UNKNOWN;
4122 		return KCFG_TRISTATE;
4123 	case BTF_KIND_ARRAY:
4124 		if (btf_array(t)->nelems == 0)
4125 			return KCFG_UNKNOWN;
4126 		if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
4127 			return KCFG_UNKNOWN;
4128 		return KCFG_CHAR_ARR;
4129 	default:
4130 		return KCFG_UNKNOWN;
4131 	}
4132 }
4133 
cmp_externs(const void * _a,const void * _b)4134 static int cmp_externs(const void *_a, const void *_b)
4135 {
4136 	const struct extern_desc *a = _a;
4137 	const struct extern_desc *b = _b;
4138 
4139 	if (a->type != b->type)
4140 		return a->type < b->type ? -1 : 1;
4141 
4142 	if (a->type == EXT_KCFG) {
4143 		/* descending order by alignment requirements */
4144 		if (a->kcfg.align != b->kcfg.align)
4145 			return a->kcfg.align > b->kcfg.align ? -1 : 1;
4146 		/* ascending order by size, within same alignment class */
4147 		if (a->kcfg.sz != b->kcfg.sz)
4148 			return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
4149 	}
4150 
4151 	/* resolve ties by name */
4152 	return strcmp(a->name, b->name);
4153 }
4154 
find_int_btf_id(const struct btf * btf)4155 static int find_int_btf_id(const struct btf *btf)
4156 {
4157 	const struct btf_type *t;
4158 	int i, n;
4159 
4160 	n = btf__type_cnt(btf);
4161 	for (i = 1; i < n; i++) {
4162 		t = btf__type_by_id(btf, i);
4163 
4164 		if (btf_is_int(t) && btf_int_bits(t) == 32)
4165 			return i;
4166 	}
4167 
4168 	return 0;
4169 }
4170 
add_dummy_ksym_var(struct btf * btf)4171 static int add_dummy_ksym_var(struct btf *btf)
4172 {
4173 	int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
4174 	const struct btf_var_secinfo *vs;
4175 	const struct btf_type *sec;
4176 
4177 	if (!btf)
4178 		return 0;
4179 
4180 	sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
4181 					    BTF_KIND_DATASEC);
4182 	if (sec_btf_id < 0)
4183 		return 0;
4184 
4185 	sec = btf__type_by_id(btf, sec_btf_id);
4186 	vs = btf_var_secinfos(sec);
4187 	for (i = 0; i < btf_vlen(sec); i++, vs++) {
4188 		const struct btf_type *vt;
4189 
4190 		vt = btf__type_by_id(btf, vs->type);
4191 		if (btf_is_func(vt))
4192 			break;
4193 	}
4194 
4195 	/* No func in ksyms sec.  No need to add dummy var. */
4196 	if (i == btf_vlen(sec))
4197 		return 0;
4198 
4199 	int_btf_id = find_int_btf_id(btf);
4200 	dummy_var_btf_id = btf__add_var(btf,
4201 					"dummy_ksym",
4202 					BTF_VAR_GLOBAL_ALLOCATED,
4203 					int_btf_id);
4204 	if (dummy_var_btf_id < 0)
4205 		pr_warn("cannot create a dummy_ksym var\n");
4206 
4207 	return dummy_var_btf_id;
4208 }
4209 
bpf_object__collect_externs(struct bpf_object * obj)4210 static int bpf_object__collect_externs(struct bpf_object *obj)
4211 {
4212 	struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
4213 	const struct btf_type *t;
4214 	struct extern_desc *ext;
4215 	int i, n, off, dummy_var_btf_id;
4216 	const char *ext_name, *sec_name;
4217 	size_t ext_essent_len;
4218 	Elf_Scn *scn;
4219 	Elf64_Shdr *sh;
4220 
4221 	if (!obj->efile.symbols)
4222 		return 0;
4223 
4224 	scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
4225 	sh = elf_sec_hdr(obj, scn);
4226 	if (!sh || sh->sh_entsize != sizeof(Elf64_Sym))
4227 		return -LIBBPF_ERRNO__FORMAT;
4228 
4229 	dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
4230 	if (dummy_var_btf_id < 0)
4231 		return dummy_var_btf_id;
4232 
4233 	n = sh->sh_size / sh->sh_entsize;
4234 	pr_debug("looking for externs among %d symbols...\n", n);
4235 
4236 	for (i = 0; i < n; i++) {
4237 		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
4238 
4239 		if (!sym)
4240 			return -LIBBPF_ERRNO__FORMAT;
4241 		if (!sym_is_extern(sym))
4242 			continue;
4243 		ext_name = elf_sym_str(obj, sym->st_name);
4244 		if (!ext_name || !ext_name[0])
4245 			continue;
4246 
4247 		ext = obj->externs;
4248 		ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
4249 		if (!ext)
4250 			return -ENOMEM;
4251 		obj->externs = ext;
4252 		ext = &ext[obj->nr_extern];
4253 		memset(ext, 0, sizeof(*ext));
4254 		obj->nr_extern++;
4255 
4256 		ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
4257 		if (ext->btf_id <= 0) {
4258 			pr_warn("failed to find BTF for extern '%s': %d\n",
4259 				ext_name, ext->btf_id);
4260 			return ext->btf_id;
4261 		}
4262 		t = btf__type_by_id(obj->btf, ext->btf_id);
4263 		ext->name = btf__name_by_offset(obj->btf, t->name_off);
4264 		ext->sym_idx = i;
4265 		ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
4266 
4267 		ext_essent_len = bpf_core_essential_name_len(ext->name);
4268 		ext->essent_name = NULL;
4269 		if (ext_essent_len != strlen(ext->name)) {
4270 			ext->essent_name = strndup(ext->name, ext_essent_len);
4271 			if (!ext->essent_name)
4272 				return -ENOMEM;
4273 		}
4274 
4275 		ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
4276 		if (ext->sec_btf_id <= 0) {
4277 			pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
4278 				ext_name, ext->btf_id, ext->sec_btf_id);
4279 			return ext->sec_btf_id;
4280 		}
4281 		sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
4282 		sec_name = btf__name_by_offset(obj->btf, sec->name_off);
4283 
4284 		if (strcmp(sec_name, KCONFIG_SEC) == 0) {
4285 			if (btf_is_func(t)) {
4286 				pr_warn("extern function %s is unsupported under %s section\n",
4287 					ext->name, KCONFIG_SEC);
4288 				return -ENOTSUP;
4289 			}
4290 			kcfg_sec = sec;
4291 			ext->type = EXT_KCFG;
4292 			ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
4293 			if (ext->kcfg.sz <= 0) {
4294 				pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
4295 					ext_name, ext->kcfg.sz);
4296 				return ext->kcfg.sz;
4297 			}
4298 			ext->kcfg.align = btf__align_of(obj->btf, t->type);
4299 			if (ext->kcfg.align <= 0) {
4300 				pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
4301 					ext_name, ext->kcfg.align);
4302 				return -EINVAL;
4303 			}
4304 			ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
4305 							&ext->kcfg.is_signed);
4306 			if (ext->kcfg.type == KCFG_UNKNOWN) {
4307 				pr_warn("extern (kcfg) '%s': type is unsupported\n", ext_name);
4308 				return -ENOTSUP;
4309 			}
4310 		} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
4311 			ksym_sec = sec;
4312 			ext->type = EXT_KSYM;
4313 			skip_mods_and_typedefs(obj->btf, t->type,
4314 					       &ext->ksym.type_id);
4315 		} else {
4316 			pr_warn("unrecognized extern section '%s'\n", sec_name);
4317 			return -ENOTSUP;
4318 		}
4319 	}
4320 	pr_debug("collected %d externs total\n", obj->nr_extern);
4321 
4322 	if (!obj->nr_extern)
4323 		return 0;
4324 
4325 	/* sort externs by type, for kcfg ones also by (align, size, name) */
4326 	qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
4327 
4328 	/* for .ksyms section, we need to turn all externs into allocated
4329 	 * variables in BTF to pass kernel verification; we do this by
4330 	 * pretending that each extern is a 8-byte variable
4331 	 */
4332 	if (ksym_sec) {
4333 		/* find existing 4-byte integer type in BTF to use for fake
4334 		 * extern variables in DATASEC
4335 		 */
4336 		int int_btf_id = find_int_btf_id(obj->btf);
4337 		/* For extern function, a dummy_var added earlier
4338 		 * will be used to replace the vs->type and
4339 		 * its name string will be used to refill
4340 		 * the missing param's name.
4341 		 */
4342 		const struct btf_type *dummy_var;
4343 
4344 		dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
4345 		for (i = 0; i < obj->nr_extern; i++) {
4346 			ext = &obj->externs[i];
4347 			if (ext->type != EXT_KSYM)
4348 				continue;
4349 			pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
4350 				 i, ext->sym_idx, ext->name);
4351 		}
4352 
4353 		sec = ksym_sec;
4354 		n = btf_vlen(sec);
4355 		for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
4356 			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
4357 			struct btf_type *vt;
4358 
4359 			vt = (void *)btf__type_by_id(obj->btf, vs->type);
4360 			ext_name = btf__name_by_offset(obj->btf, vt->name_off);
4361 			ext = find_extern_by_name(obj, ext_name);
4362 			if (!ext) {
4363 				pr_warn("failed to find extern definition for BTF %s '%s'\n",
4364 					btf_kind_str(vt), ext_name);
4365 				return -ESRCH;
4366 			}
4367 			if (btf_is_func(vt)) {
4368 				const struct btf_type *func_proto;
4369 				struct btf_param *param;
4370 				int j;
4371 
4372 				func_proto = btf__type_by_id(obj->btf,
4373 							     vt->type);
4374 				param = btf_params(func_proto);
4375 				/* Reuse the dummy_var string if the
4376 				 * func proto does not have param name.
4377 				 */
4378 				for (j = 0; j < btf_vlen(func_proto); j++)
4379 					if (param[j].type && !param[j].name_off)
4380 						param[j].name_off =
4381 							dummy_var->name_off;
4382 				vs->type = dummy_var_btf_id;
4383 				vt->info &= ~0xffff;
4384 				vt->info |= BTF_FUNC_GLOBAL;
4385 			} else {
4386 				btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
4387 				vt->type = int_btf_id;
4388 			}
4389 			vs->offset = off;
4390 			vs->size = sizeof(int);
4391 		}
4392 		sec->size = off;
4393 	}
4394 
4395 	if (kcfg_sec) {
4396 		sec = kcfg_sec;
4397 		/* for kcfg externs calculate their offsets within a .kconfig map */
4398 		off = 0;
4399 		for (i = 0; i < obj->nr_extern; i++) {
4400 			ext = &obj->externs[i];
4401 			if (ext->type != EXT_KCFG)
4402 				continue;
4403 
4404 			ext->kcfg.data_off = roundup(off, ext->kcfg.align);
4405 			off = ext->kcfg.data_off + ext->kcfg.sz;
4406 			pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
4407 				 i, ext->sym_idx, ext->kcfg.data_off, ext->name);
4408 		}
4409 		sec->size = off;
4410 		n = btf_vlen(sec);
4411 		for (i = 0; i < n; i++) {
4412 			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
4413 
4414 			t = btf__type_by_id(obj->btf, vs->type);
4415 			ext_name = btf__name_by_offset(obj->btf, t->name_off);
4416 			ext = find_extern_by_name(obj, ext_name);
4417 			if (!ext) {
4418 				pr_warn("failed to find extern definition for BTF var '%s'\n",
4419 					ext_name);
4420 				return -ESRCH;
4421 			}
4422 			btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
4423 			vs->offset = ext->kcfg.data_off;
4424 		}
4425 	}
4426 	return 0;
4427 }
4428 
prog_is_subprog(const struct bpf_object * obj,const struct bpf_program * prog)4429 static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog)
4430 {
4431 	return prog->sec_idx == obj->efile.text_shndx;
4432 }
4433 
4434 struct bpf_program *
bpf_object__find_program_by_name(const struct bpf_object * obj,const char * name)4435 bpf_object__find_program_by_name(const struct bpf_object *obj,
4436 				 const char *name)
4437 {
4438 	struct bpf_program *prog;
4439 
4440 	bpf_object__for_each_program(prog, obj) {
4441 		if (prog_is_subprog(obj, prog))
4442 			continue;
4443 		if (!strcmp(prog->name, name))
4444 			return prog;
4445 	}
4446 	return errno = ENOENT, NULL;
4447 }
4448 
bpf_object__shndx_is_data(const struct bpf_object * obj,int shndx)4449 static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
4450 				      int shndx)
4451 {
4452 	switch (obj->efile.secs[shndx].sec_type) {
4453 	case SEC_BSS:
4454 	case SEC_DATA:
4455 	case SEC_RODATA:
4456 		return true;
4457 	default:
4458 		return false;
4459 	}
4460 }
4461 
bpf_object__shndx_is_maps(const struct bpf_object * obj,int shndx)4462 static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
4463 				      int shndx)
4464 {
4465 	return shndx == obj->efile.btf_maps_shndx;
4466 }
4467 
4468 static enum libbpf_map_type
bpf_object__section_to_libbpf_map_type(const struct bpf_object * obj,int shndx)4469 bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
4470 {
4471 	if (shndx == obj->efile.symbols_shndx)
4472 		return LIBBPF_MAP_KCONFIG;
4473 
4474 	switch (obj->efile.secs[shndx].sec_type) {
4475 	case SEC_BSS:
4476 		return LIBBPF_MAP_BSS;
4477 	case SEC_DATA:
4478 		return LIBBPF_MAP_DATA;
4479 	case SEC_RODATA:
4480 		return LIBBPF_MAP_RODATA;
4481 	default:
4482 		return LIBBPF_MAP_UNSPEC;
4483 	}
4484 }
4485 
bpf_program__record_reloc(struct bpf_program * prog,struct reloc_desc * reloc_desc,__u32 insn_idx,const char * sym_name,const Elf64_Sym * sym,const Elf64_Rel * rel)4486 static int bpf_program__record_reloc(struct bpf_program *prog,
4487 				     struct reloc_desc *reloc_desc,
4488 				     __u32 insn_idx, const char *sym_name,
4489 				     const Elf64_Sym *sym, const Elf64_Rel *rel)
4490 {
4491 	struct bpf_insn *insn = &prog->insns[insn_idx];
4492 	size_t map_idx, nr_maps = prog->obj->nr_maps;
4493 	struct bpf_object *obj = prog->obj;
4494 	__u32 shdr_idx = sym->st_shndx;
4495 	enum libbpf_map_type type;
4496 	const char *sym_sec_name;
4497 	struct bpf_map *map;
4498 
4499 	if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
4500 		pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
4501 			prog->name, sym_name, insn_idx, insn->code);
4502 		return -LIBBPF_ERRNO__RELOC;
4503 	}
4504 
4505 	if (sym_is_extern(sym)) {
4506 		int sym_idx = ELF64_R_SYM(rel->r_info);
4507 		int i, n = obj->nr_extern;
4508 		struct extern_desc *ext;
4509 
4510 		for (i = 0; i < n; i++) {
4511 			ext = &obj->externs[i];
4512 			if (ext->sym_idx == sym_idx)
4513 				break;
4514 		}
4515 		if (i >= n) {
4516 			pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
4517 				prog->name, sym_name, sym_idx);
4518 			return -LIBBPF_ERRNO__RELOC;
4519 		}
4520 		pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
4521 			 prog->name, i, ext->name, ext->sym_idx, insn_idx);
4522 		if (insn->code == (BPF_JMP | BPF_CALL))
4523 			reloc_desc->type = RELO_EXTERN_CALL;
4524 		else
4525 			reloc_desc->type = RELO_EXTERN_LD64;
4526 		reloc_desc->insn_idx = insn_idx;
4527 		reloc_desc->ext_idx = i;
4528 		return 0;
4529 	}
4530 
4531 	/* sub-program call relocation */
4532 	if (is_call_insn(insn)) {
4533 		if (insn->src_reg != BPF_PSEUDO_CALL) {
4534 			pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
4535 			return -LIBBPF_ERRNO__RELOC;
4536 		}
4537 		/* text_shndx can be 0, if no default "main" program exists */
4538 		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
4539 			sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
4540 			pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
4541 				prog->name, sym_name, sym_sec_name);
4542 			return -LIBBPF_ERRNO__RELOC;
4543 		}
4544 		if (sym->st_value % BPF_INSN_SZ) {
4545 			pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
4546 				prog->name, sym_name, (size_t)sym->st_value);
4547 			return -LIBBPF_ERRNO__RELOC;
4548 		}
4549 		reloc_desc->type = RELO_CALL;
4550 		reloc_desc->insn_idx = insn_idx;
4551 		reloc_desc->sym_off = sym->st_value;
4552 		return 0;
4553 	}
4554 
4555 	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
4556 		pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
4557 			prog->name, sym_name, shdr_idx);
4558 		return -LIBBPF_ERRNO__RELOC;
4559 	}
4560 
4561 	/* loading subprog addresses */
4562 	if (sym_is_subprog(sym, obj->efile.text_shndx)) {
4563 		/* global_func: sym->st_value = offset in the section, insn->imm = 0.
4564 		 * local_func: sym->st_value = 0, insn->imm = offset in the section.
4565 		 */
4566 		if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
4567 			pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
4568 				prog->name, sym_name, (size_t)sym->st_value, insn->imm);
4569 			return -LIBBPF_ERRNO__RELOC;
4570 		}
4571 
4572 		reloc_desc->type = RELO_SUBPROG_ADDR;
4573 		reloc_desc->insn_idx = insn_idx;
4574 		reloc_desc->sym_off = sym->st_value;
4575 		return 0;
4576 	}
4577 
4578 	type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
4579 	sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
4580 
4581 	/* arena data relocation */
4582 	if (shdr_idx == obj->efile.arena_data_shndx) {
4583 		reloc_desc->type = RELO_DATA;
4584 		reloc_desc->insn_idx = insn_idx;
4585 		reloc_desc->map_idx = obj->arena_map - obj->maps;
4586 		reloc_desc->sym_off = sym->st_value;
4587 		return 0;
4588 	}
4589 
4590 	/* generic map reference relocation */
4591 	if (type == LIBBPF_MAP_UNSPEC) {
4592 		if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
4593 			pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
4594 				prog->name, sym_name, sym_sec_name);
4595 			return -LIBBPF_ERRNO__RELOC;
4596 		}
4597 		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
4598 			map = &obj->maps[map_idx];
4599 			if (map->libbpf_type != type ||
4600 			    map->sec_idx != sym->st_shndx ||
4601 			    map->sec_offset != sym->st_value)
4602 				continue;
4603 			pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
4604 				 prog->name, map_idx, map->name, map->sec_idx,
4605 				 map->sec_offset, insn_idx);
4606 			break;
4607 		}
4608 		if (map_idx >= nr_maps) {
4609 			pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
4610 				prog->name, sym_sec_name, (size_t)sym->st_value);
4611 			return -LIBBPF_ERRNO__RELOC;
4612 		}
4613 		reloc_desc->type = RELO_LD64;
4614 		reloc_desc->insn_idx = insn_idx;
4615 		reloc_desc->map_idx = map_idx;
4616 		reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
4617 		return 0;
4618 	}
4619 
4620 	/* global data map relocation */
4621 	if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
4622 		pr_warn("prog '%s': bad data relo against section '%s'\n",
4623 			prog->name, sym_sec_name);
4624 		return -LIBBPF_ERRNO__RELOC;
4625 	}
4626 	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
4627 		map = &obj->maps[map_idx];
4628 		if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
4629 			continue;
4630 		pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
4631 			 prog->name, map_idx, map->name, map->sec_idx,
4632 			 map->sec_offset, insn_idx);
4633 		break;
4634 	}
4635 	if (map_idx >= nr_maps) {
4636 		pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
4637 			prog->name, sym_sec_name);
4638 		return -LIBBPF_ERRNO__RELOC;
4639 	}
4640 
4641 	reloc_desc->type = RELO_DATA;
4642 	reloc_desc->insn_idx = insn_idx;
4643 	reloc_desc->map_idx = map_idx;
4644 	reloc_desc->sym_off = sym->st_value;
4645 	return 0;
4646 }
4647 
prog_contains_insn(const struct bpf_program * prog,size_t insn_idx)4648 static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
4649 {
4650 	return insn_idx >= prog->sec_insn_off &&
4651 	       insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
4652 }
4653 
find_prog_by_sec_insn(const struct bpf_object * obj,size_t sec_idx,size_t insn_idx)4654 static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
4655 						 size_t sec_idx, size_t insn_idx)
4656 {
4657 	int l = 0, r = obj->nr_programs - 1, m;
4658 	struct bpf_program *prog;
4659 
4660 	if (!obj->nr_programs)
4661 		return NULL;
4662 
4663 	while (l < r) {
4664 		m = l + (r - l + 1) / 2;
4665 		prog = &obj->programs[m];
4666 
4667 		if (prog->sec_idx < sec_idx ||
4668 		    (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
4669 			l = m;
4670 		else
4671 			r = m - 1;
4672 	}
4673 	/* matching program could be at index l, but it still might be the
4674 	 * wrong one, so we need to double check conditions for the last time
4675 	 */
4676 	prog = &obj->programs[l];
4677 	if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
4678 		return prog;
4679 	return NULL;
4680 }
4681 
4682 static int
bpf_object__collect_prog_relos(struct bpf_object * obj,Elf64_Shdr * shdr,Elf_Data * data)4683 bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data)
4684 {
4685 	const char *relo_sec_name, *sec_name;
4686 	size_t sec_idx = shdr->sh_info, sym_idx;
4687 	struct bpf_program *prog;
4688 	struct reloc_desc *relos;
4689 	int err, i, nrels;
4690 	const char *sym_name;
4691 	__u32 insn_idx;
4692 	Elf_Scn *scn;
4693 	Elf_Data *scn_data;
4694 	Elf64_Sym *sym;
4695 	Elf64_Rel *rel;
4696 
4697 	if (sec_idx >= obj->efile.sec_cnt)
4698 		return -EINVAL;
4699 
4700 	scn = elf_sec_by_idx(obj, sec_idx);
4701 	scn_data = elf_sec_data(obj, scn);
4702 	if (!scn_data)
4703 		return -LIBBPF_ERRNO__FORMAT;
4704 
4705 	relo_sec_name = elf_sec_str(obj, shdr->sh_name);
4706 	sec_name = elf_sec_name(obj, scn);
4707 	if (!relo_sec_name || !sec_name)
4708 		return -EINVAL;
4709 
4710 	pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
4711 		 relo_sec_name, sec_idx, sec_name);
4712 	nrels = shdr->sh_size / shdr->sh_entsize;
4713 
4714 	for (i = 0; i < nrels; i++) {
4715 		rel = elf_rel_by_idx(data, i);
4716 		if (!rel) {
4717 			pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
4718 			return -LIBBPF_ERRNO__FORMAT;
4719 		}
4720 
4721 		sym_idx = ELF64_R_SYM(rel->r_info);
4722 		sym = elf_sym_by_idx(obj, sym_idx);
4723 		if (!sym) {
4724 			pr_warn("sec '%s': symbol #%zu not found for relo #%d\n",
4725 				relo_sec_name, sym_idx, i);
4726 			return -LIBBPF_ERRNO__FORMAT;
4727 		}
4728 
4729 		if (sym->st_shndx >= obj->efile.sec_cnt) {
4730 			pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n",
4731 				relo_sec_name, sym_idx, (size_t)sym->st_shndx, i);
4732 			return -LIBBPF_ERRNO__FORMAT;
4733 		}
4734 
4735 		if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
4736 			pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
4737 				relo_sec_name, (size_t)rel->r_offset, i);
4738 			return -LIBBPF_ERRNO__FORMAT;
4739 		}
4740 
4741 		insn_idx = rel->r_offset / BPF_INSN_SZ;
4742 		/* relocations against static functions are recorded as
4743 		 * relocations against the section that contains a function;
4744 		 * in such case, symbol will be STT_SECTION and sym.st_name
4745 		 * will point to empty string (0), so fetch section name
4746 		 * instead
4747 		 */
4748 		if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0)
4749 			sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx));
4750 		else
4751 			sym_name = elf_sym_str(obj, sym->st_name);
4752 		sym_name = sym_name ?: "<?";
4753 
4754 		pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
4755 			 relo_sec_name, i, insn_idx, sym_name);
4756 
4757 		prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
4758 		if (!prog) {
4759 			pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
4760 				relo_sec_name, i, sec_name, insn_idx);
4761 			continue;
4762 		}
4763 
4764 		relos = libbpf_reallocarray(prog->reloc_desc,
4765 					    prog->nr_reloc + 1, sizeof(*relos));
4766 		if (!relos)
4767 			return -ENOMEM;
4768 		prog->reloc_desc = relos;
4769 
4770 		/* adjust insn_idx to local BPF program frame of reference */
4771 		insn_idx -= prog->sec_insn_off;
4772 		err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
4773 						insn_idx, sym_name, sym, rel);
4774 		if (err)
4775 			return err;
4776 
4777 		prog->nr_reloc++;
4778 	}
4779 	return 0;
4780 }
4781 
map_fill_btf_type_info(struct bpf_object * obj,struct bpf_map * map)4782 static int map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map)
4783 {
4784 	int id;
4785 
4786 	if (!obj->btf)
4787 		return -ENOENT;
4788 
4789 	/* if it's BTF-defined map, we don't need to search for type IDs.
4790 	 * For struct_ops map, it does not need btf_key_type_id and
4791 	 * btf_value_type_id.
4792 	 */
4793 	if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map))
4794 		return 0;
4795 
4796 	/*
4797 	 * LLVM annotates global data differently in BTF, that is,
4798 	 * only as '.data', '.bss' or '.rodata'.
4799 	 */
4800 	if (!bpf_map__is_internal(map))
4801 		return -ENOENT;
4802 
4803 	id = btf__find_by_name(obj->btf, map->real_name);
4804 	if (id < 0)
4805 		return id;
4806 
4807 	map->btf_key_type_id = 0;
4808 	map->btf_value_type_id = id;
4809 	return 0;
4810 }
4811 
bpf_get_map_info_from_fdinfo(int fd,struct bpf_map_info * info)4812 static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
4813 {
4814 	char file[PATH_MAX], buff[4096];
4815 	FILE *fp;
4816 	__u32 val;
4817 	int err;
4818 
4819 	snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
4820 	memset(info, 0, sizeof(*info));
4821 
4822 	fp = fopen(file, "re");
4823 	if (!fp) {
4824 		err = -errno;
4825 		pr_warn("failed to open %s: %s. No procfs support?\n", file,
4826 			errstr(err));
4827 		return err;
4828 	}
4829 
4830 	while (fgets(buff, sizeof(buff), fp)) {
4831 		if (sscanf(buff, "map_type:\t%u", &val) == 1)
4832 			info->type = val;
4833 		else if (sscanf(buff, "key_size:\t%u", &val) == 1)
4834 			info->key_size = val;
4835 		else if (sscanf(buff, "value_size:\t%u", &val) == 1)
4836 			info->value_size = val;
4837 		else if (sscanf(buff, "max_entries:\t%u", &val) == 1)
4838 			info->max_entries = val;
4839 		else if (sscanf(buff, "map_flags:\t%i", &val) == 1)
4840 			info->map_flags = val;
4841 	}
4842 
4843 	fclose(fp);
4844 
4845 	return 0;
4846 }
4847 
bpf_map__autocreate(const struct bpf_map * map)4848 bool bpf_map__autocreate(const struct bpf_map *map)
4849 {
4850 	return map->autocreate;
4851 }
4852 
bpf_map__set_autocreate(struct bpf_map * map,bool autocreate)4853 int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
4854 {
4855 	if (map->obj->loaded)
4856 		return libbpf_err(-EBUSY);
4857 
4858 	map->autocreate = autocreate;
4859 	return 0;
4860 }
4861 
bpf_map__set_autoattach(struct bpf_map * map,bool autoattach)4862 int bpf_map__set_autoattach(struct bpf_map *map, bool autoattach)
4863 {
4864 	if (!bpf_map__is_struct_ops(map))
4865 		return libbpf_err(-EINVAL);
4866 
4867 	map->autoattach = autoattach;
4868 	return 0;
4869 }
4870 
bpf_map__autoattach(const struct bpf_map * map)4871 bool bpf_map__autoattach(const struct bpf_map *map)
4872 {
4873 	return map->autoattach;
4874 }
4875 
bpf_map__reuse_fd(struct bpf_map * map,int fd)4876 int bpf_map__reuse_fd(struct bpf_map *map, int fd)
4877 {
4878 	struct bpf_map_info info;
4879 	__u32 len = sizeof(info), name_len;
4880 	int new_fd, err;
4881 	char *new_name;
4882 
4883 	memset(&info, 0, len);
4884 	err = bpf_map_get_info_by_fd(fd, &info, &len);
4885 	if (err && errno == EINVAL)
4886 		err = bpf_get_map_info_from_fdinfo(fd, &info);
4887 	if (err)
4888 		return libbpf_err(err);
4889 
4890 	name_len = strlen(info.name);
4891 	if (name_len == BPF_OBJ_NAME_LEN - 1 && strncmp(map->name, info.name, name_len) == 0)
4892 		new_name = strdup(map->name);
4893 	else
4894 		new_name = strdup(info.name);
4895 
4896 	if (!new_name)
4897 		return libbpf_err(-errno);
4898 
4899 	/*
4900 	 * Like dup(), but make sure new FD is >= 3 and has O_CLOEXEC set.
4901 	 * This is similar to what we do in ensure_good_fd(), but without
4902 	 * closing original FD.
4903 	 */
4904 	new_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
4905 	if (new_fd < 0) {
4906 		err = -errno;
4907 		goto err_free_new_name;
4908 	}
4909 
4910 	err = reuse_fd(map->fd, new_fd);
4911 	if (err)
4912 		goto err_free_new_name;
4913 
4914 	free(map->name);
4915 
4916 	map->name = new_name;
4917 	map->def.type = info.type;
4918 	map->def.key_size = info.key_size;
4919 	map->def.value_size = info.value_size;
4920 	map->def.max_entries = info.max_entries;
4921 	map->def.map_flags = info.map_flags;
4922 	map->btf_key_type_id = info.btf_key_type_id;
4923 	map->btf_value_type_id = info.btf_value_type_id;
4924 	map->reused = true;
4925 	map->map_extra = info.map_extra;
4926 
4927 	return 0;
4928 
4929 err_free_new_name:
4930 	free(new_name);
4931 	return libbpf_err(err);
4932 }
4933 
bpf_map__max_entries(const struct bpf_map * map)4934 __u32 bpf_map__max_entries(const struct bpf_map *map)
4935 {
4936 	return map->def.max_entries;
4937 }
4938 
bpf_map__inner_map(struct bpf_map * map)4939 struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
4940 {
4941 	if (!bpf_map_type__is_map_in_map(map->def.type))
4942 		return errno = EINVAL, NULL;
4943 
4944 	return map->inner_map;
4945 }
4946 
bpf_map__set_max_entries(struct bpf_map * map,__u32 max_entries)4947 int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
4948 {
4949 	if (map->obj->loaded)
4950 		return libbpf_err(-EBUSY);
4951 
4952 	map->def.max_entries = max_entries;
4953 
4954 	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
4955 	if (map_is_ringbuf(map))
4956 		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
4957 
4958 	return 0;
4959 }
4960 
bpf_object_prepare_token(struct bpf_object * obj)4961 static int bpf_object_prepare_token(struct bpf_object *obj)
4962 {
4963 	const char *bpffs_path;
4964 	int bpffs_fd = -1, token_fd, err;
4965 	bool mandatory;
4966 	enum libbpf_print_level level;
4967 
4968 	/* token is explicitly prevented */
4969 	if (obj->token_path && obj->token_path[0] == '\0') {
4970 		pr_debug("object '%s': token is prevented, skipping...\n", obj->name);
4971 		return 0;
4972 	}
4973 
4974 	mandatory = obj->token_path != NULL;
4975 	level = mandatory ? LIBBPF_WARN : LIBBPF_DEBUG;
4976 
4977 	bpffs_path = obj->token_path ?: BPF_FS_DEFAULT_PATH;
4978 	bpffs_fd = open(bpffs_path, O_DIRECTORY, O_RDWR);
4979 	if (bpffs_fd < 0) {
4980 		err = -errno;
4981 		__pr(level, "object '%s': failed (%s) to open BPF FS mount at '%s'%s\n",
4982 		     obj->name, errstr(err), bpffs_path,
4983 		     mandatory ? "" : ", skipping optional step...");
4984 		return mandatory ? err : 0;
4985 	}
4986 
4987 	token_fd = bpf_token_create(bpffs_fd, 0);
4988 	close(bpffs_fd);
4989 	if (token_fd < 0) {
4990 		if (!mandatory && token_fd == -ENOENT) {
4991 			pr_debug("object '%s': BPF FS at '%s' doesn't have BPF token delegation set up, skipping...\n",
4992 				 obj->name, bpffs_path);
4993 			return 0;
4994 		}
4995 		__pr(level, "object '%s': failed (%d) to create BPF token from '%s'%s\n",
4996 		     obj->name, token_fd, bpffs_path,
4997 		     mandatory ? "" : ", skipping optional step...");
4998 		return mandatory ? token_fd : 0;
4999 	}
5000 
5001 	obj->feat_cache = calloc(1, sizeof(*obj->feat_cache));
5002 	if (!obj->feat_cache) {
5003 		close(token_fd);
5004 		return -ENOMEM;
5005 	}
5006 
5007 	obj->token_fd = token_fd;
5008 	obj->feat_cache->token_fd = token_fd;
5009 
5010 	return 0;
5011 }
5012 
5013 static int
bpf_object__probe_loading(struct bpf_object * obj)5014 bpf_object__probe_loading(struct bpf_object *obj)
5015 {
5016 	struct bpf_insn insns[] = {
5017 		BPF_MOV64_IMM(BPF_REG_0, 0),
5018 		BPF_EXIT_INSN(),
5019 	};
5020 	int ret, insn_cnt = ARRAY_SIZE(insns);
5021 	LIBBPF_OPTS(bpf_prog_load_opts, opts,
5022 		.token_fd = obj->token_fd,
5023 		.prog_flags = obj->token_fd ? BPF_F_TOKEN_FD : 0,
5024 	);
5025 
5026 	if (obj->gen_loader)
5027 		return 0;
5028 
5029 	ret = bump_rlimit_memlock();
5030 	if (ret)
5031 		pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %s), you might need to do it explicitly!\n",
5032 			errstr(ret));
5033 
5034 	/* make sure basic loading works */
5035 	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, &opts);
5036 	if (ret < 0)
5037 		ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts);
5038 	if (ret < 0) {
5039 		ret = errno;
5040 		pr_warn("Error in %s(): %s. Couldn't load trivial BPF program. Make sure your kernel supports BPF (CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is set to big enough value.\n",
5041 			__func__, errstr(ret));
5042 		return -ret;
5043 	}
5044 	close(ret);
5045 
5046 	return 0;
5047 }
5048 
kernel_supports(const struct bpf_object * obj,enum kern_feature_id feat_id)5049 bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
5050 {
5051 	if (obj->gen_loader)
5052 		/* To generate loader program assume the latest kernel
5053 		 * to avoid doing extra prog_load, map_create syscalls.
5054 		 */
5055 		return true;
5056 
5057 	if (obj->token_fd)
5058 		return feat_supported(obj->feat_cache, feat_id);
5059 
5060 	return feat_supported(NULL, feat_id);
5061 }
5062 
map_is_reuse_compat(const struct bpf_map * map,int map_fd)5063 static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
5064 {
5065 	struct bpf_map_info map_info;
5066 	__u32 map_info_len = sizeof(map_info);
5067 	int err;
5068 
5069 	memset(&map_info, 0, map_info_len);
5070 	err = bpf_map_get_info_by_fd(map_fd, &map_info, &map_info_len);
5071 	if (err && errno == EINVAL)
5072 		err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
5073 	if (err) {
5074 		pr_warn("failed to get map info for map FD %d: %s\n", map_fd,
5075 			errstr(err));
5076 		return false;
5077 	}
5078 
5079 	return (map_info.type == map->def.type &&
5080 		map_info.key_size == map->def.key_size &&
5081 		map_info.value_size == map->def.value_size &&
5082 		map_info.max_entries == map->def.max_entries &&
5083 		map_info.map_flags == map->def.map_flags &&
5084 		map_info.map_extra == map->map_extra);
5085 }
5086 
5087 static int
bpf_object__reuse_map(struct bpf_map * map)5088 bpf_object__reuse_map(struct bpf_map *map)
5089 {
5090 	int err, pin_fd;
5091 
5092 	pin_fd = bpf_obj_get(map->pin_path);
5093 	if (pin_fd < 0) {
5094 		err = -errno;
5095 		if (err == -ENOENT) {
5096 			pr_debug("found no pinned map to reuse at '%s'\n",
5097 				 map->pin_path);
5098 			return 0;
5099 		}
5100 
5101 		pr_warn("couldn't retrieve pinned map '%s': %s\n",
5102 			map->pin_path, errstr(err));
5103 		return err;
5104 	}
5105 
5106 	if (!map_is_reuse_compat(map, pin_fd)) {
5107 		pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
5108 			map->pin_path);
5109 		close(pin_fd);
5110 		return -EINVAL;
5111 	}
5112 
5113 	err = bpf_map__reuse_fd(map, pin_fd);
5114 	close(pin_fd);
5115 	if (err)
5116 		return err;
5117 
5118 	map->pinned = true;
5119 	pr_debug("reused pinned map at '%s'\n", map->pin_path);
5120 
5121 	return 0;
5122 }
5123 
5124 static int
bpf_object__populate_internal_map(struct bpf_object * obj,struct bpf_map * map)5125 bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
5126 {
5127 	enum libbpf_map_type map_type = map->libbpf_type;
5128 	int err, zero = 0;
5129 	size_t mmap_sz;
5130 
5131 	if (obj->gen_loader) {
5132 		bpf_gen__map_update_elem(obj->gen_loader, map - obj->maps,
5133 					 map->mmaped, map->def.value_size);
5134 		if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG)
5135 			bpf_gen__map_freeze(obj->gen_loader, map - obj->maps);
5136 		return 0;
5137 	}
5138 
5139 	err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
5140 	if (err) {
5141 		err = -errno;
5142 		pr_warn("map '%s': failed to set initial contents: %s\n",
5143 			bpf_map__name(map), errstr(err));
5144 		return err;
5145 	}
5146 
5147 	/* Freeze .rodata and .kconfig map as read-only from syscall side. */
5148 	if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
5149 		err = bpf_map_freeze(map->fd);
5150 		if (err) {
5151 			err = -errno;
5152 			pr_warn("map '%s': failed to freeze as read-only: %s\n",
5153 				bpf_map__name(map), errstr(err));
5154 			return err;
5155 		}
5156 	}
5157 
5158 	/* Remap anonymous mmap()-ed "map initialization image" as
5159 	 * a BPF map-backed mmap()-ed memory, but preserving the same
5160 	 * memory address. This will cause kernel to change process'
5161 	 * page table to point to a different piece of kernel memory,
5162 	 * but from userspace point of view memory address (and its
5163 	 * contents, being identical at this point) will stay the
5164 	 * same. This mapping will be released by bpf_object__close()
5165 	 * as per normal clean up procedure.
5166 	 */
5167 	mmap_sz = bpf_map_mmap_sz(map);
5168 	if (map->def.map_flags & BPF_F_MMAPABLE) {
5169 		void *mmaped;
5170 		int prot;
5171 
5172 		if (map->def.map_flags & BPF_F_RDONLY_PROG)
5173 			prot = PROT_READ;
5174 		else
5175 			prot = PROT_READ | PROT_WRITE;
5176 		mmaped = mmap(map->mmaped, mmap_sz, prot, MAP_SHARED | MAP_FIXED, map->fd, 0);
5177 		if (mmaped == MAP_FAILED) {
5178 			err = -errno;
5179 			pr_warn("map '%s': failed to re-mmap() contents: %s\n",
5180 				bpf_map__name(map), errstr(err));
5181 			return err;
5182 		}
5183 		map->mmaped = mmaped;
5184 	} else if (map->mmaped) {
5185 		munmap(map->mmaped, mmap_sz);
5186 		map->mmaped = NULL;
5187 	}
5188 
5189 	return 0;
5190 }
5191 
5192 static void bpf_map__destroy(struct bpf_map *map);
5193 
map_is_created(const struct bpf_map * map)5194 static bool map_is_created(const struct bpf_map *map)
5195 {
5196 	return map->obj->loaded || map->reused;
5197 }
5198 
bpf_object__create_map(struct bpf_object * obj,struct bpf_map * map,bool is_inner)5199 static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
5200 {
5201 	LIBBPF_OPTS(bpf_map_create_opts, create_attr);
5202 	struct bpf_map_def *def = &map->def;
5203 	const char *map_name = NULL;
5204 	int err = 0, map_fd;
5205 
5206 	if (kernel_supports(obj, FEAT_PROG_NAME))
5207 		map_name = map->name;
5208 	create_attr.map_ifindex = map->map_ifindex;
5209 	create_attr.map_flags = def->map_flags;
5210 	create_attr.numa_node = map->numa_node;
5211 	create_attr.map_extra = map->map_extra;
5212 	create_attr.token_fd = obj->token_fd;
5213 	if (obj->token_fd)
5214 		create_attr.map_flags |= BPF_F_TOKEN_FD;
5215 
5216 	if (bpf_map__is_struct_ops(map)) {
5217 		create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
5218 		if (map->mod_btf_fd >= 0) {
5219 			create_attr.value_type_btf_obj_fd = map->mod_btf_fd;
5220 			create_attr.map_flags |= BPF_F_VTYPE_BTF_OBJ_FD;
5221 		}
5222 	}
5223 
5224 	if (obj->btf && btf__fd(obj->btf) >= 0) {
5225 		create_attr.btf_fd = btf__fd(obj->btf);
5226 		create_attr.btf_key_type_id = map->btf_key_type_id;
5227 		create_attr.btf_value_type_id = map->btf_value_type_id;
5228 	}
5229 
5230 	if (bpf_map_type__is_map_in_map(def->type)) {
5231 		if (map->inner_map) {
5232 			err = map_set_def_max_entries(map->inner_map);
5233 			if (err)
5234 				return err;
5235 			err = bpf_object__create_map(obj, map->inner_map, true);
5236 			if (err) {
5237 				pr_warn("map '%s': failed to create inner map: %s\n",
5238 					map->name, errstr(err));
5239 				return err;
5240 			}
5241 			map->inner_map_fd = map->inner_map->fd;
5242 		}
5243 		if (map->inner_map_fd >= 0)
5244 			create_attr.inner_map_fd = map->inner_map_fd;
5245 	}
5246 
5247 	switch (def->type) {
5248 	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
5249 	case BPF_MAP_TYPE_CGROUP_ARRAY:
5250 	case BPF_MAP_TYPE_STACK_TRACE:
5251 	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
5252 	case BPF_MAP_TYPE_HASH_OF_MAPS:
5253 	case BPF_MAP_TYPE_DEVMAP:
5254 	case BPF_MAP_TYPE_DEVMAP_HASH:
5255 	case BPF_MAP_TYPE_CPUMAP:
5256 	case BPF_MAP_TYPE_XSKMAP:
5257 	case BPF_MAP_TYPE_SOCKMAP:
5258 	case BPF_MAP_TYPE_SOCKHASH:
5259 	case BPF_MAP_TYPE_QUEUE:
5260 	case BPF_MAP_TYPE_STACK:
5261 	case BPF_MAP_TYPE_ARENA:
5262 		create_attr.btf_fd = 0;
5263 		create_attr.btf_key_type_id = 0;
5264 		create_attr.btf_value_type_id = 0;
5265 		map->btf_key_type_id = 0;
5266 		map->btf_value_type_id = 0;
5267 		break;
5268 	case BPF_MAP_TYPE_STRUCT_OPS:
5269 		create_attr.btf_value_type_id = 0;
5270 		break;
5271 	default:
5272 		break;
5273 	}
5274 
5275 	if (obj->gen_loader) {
5276 		bpf_gen__map_create(obj->gen_loader, def->type, map_name,
5277 				    def->key_size, def->value_size, def->max_entries,
5278 				    &create_attr, is_inner ? -1 : map - obj->maps);
5279 		/* We keep pretenting we have valid FD to pass various fd >= 0
5280 		 * checks by just keeping original placeholder FDs in place.
5281 		 * See bpf_object__add_map() comment.
5282 		 * This placeholder fd will not be used with any syscall and
5283 		 * will be reset to -1 eventually.
5284 		 */
5285 		map_fd = map->fd;
5286 	} else {
5287 		map_fd = bpf_map_create(def->type, map_name,
5288 					def->key_size, def->value_size,
5289 					def->max_entries, &create_attr);
5290 	}
5291 	if (map_fd < 0 && (create_attr.btf_key_type_id || create_attr.btf_value_type_id)) {
5292 		err = -errno;
5293 		pr_warn("Error in bpf_create_map_xattr(%s): %s. Retrying without BTF.\n",
5294 			map->name, errstr(err));
5295 		create_attr.btf_fd = 0;
5296 		create_attr.btf_key_type_id = 0;
5297 		create_attr.btf_value_type_id = 0;
5298 		map->btf_key_type_id = 0;
5299 		map->btf_value_type_id = 0;
5300 		map_fd = bpf_map_create(def->type, map_name,
5301 					def->key_size, def->value_size,
5302 					def->max_entries, &create_attr);
5303 	}
5304 
5305 	if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
5306 		if (obj->gen_loader)
5307 			map->inner_map->fd = -1;
5308 		bpf_map__destroy(map->inner_map);
5309 		zfree(&map->inner_map);
5310 	}
5311 
5312 	if (map_fd < 0)
5313 		return map_fd;
5314 
5315 	/* obj->gen_loader case, prevent reuse_fd() from closing map_fd */
5316 	if (map->fd == map_fd)
5317 		return 0;
5318 
5319 	/* Keep placeholder FD value but now point it to the BPF map object.
5320 	 * This way everything that relied on this map's FD (e.g., relocated
5321 	 * ldimm64 instructions) will stay valid and won't need adjustments.
5322 	 * map->fd stays valid but now point to what map_fd points to.
5323 	 */
5324 	return reuse_fd(map->fd, map_fd);
5325 }
5326 
init_map_in_map_slots(struct bpf_object * obj,struct bpf_map * map)5327 static int init_map_in_map_slots(struct bpf_object *obj, struct bpf_map *map)
5328 {
5329 	const struct bpf_map *targ_map;
5330 	unsigned int i;
5331 	int fd, err = 0;
5332 
5333 	for (i = 0; i < map->init_slots_sz; i++) {
5334 		if (!map->init_slots[i])
5335 			continue;
5336 
5337 		targ_map = map->init_slots[i];
5338 		fd = targ_map->fd;
5339 
5340 		if (obj->gen_loader) {
5341 			bpf_gen__populate_outer_map(obj->gen_loader,
5342 						    map - obj->maps, i,
5343 						    targ_map - obj->maps);
5344 		} else {
5345 			err = bpf_map_update_elem(map->fd, &i, &fd, 0);
5346 		}
5347 		if (err) {
5348 			err = -errno;
5349 			pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %s\n",
5350 				map->name, i, targ_map->name, fd, errstr(err));
5351 			return err;
5352 		}
5353 		pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
5354 			 map->name, i, targ_map->name, fd);
5355 	}
5356 
5357 	zfree(&map->init_slots);
5358 	map->init_slots_sz = 0;
5359 
5360 	return 0;
5361 }
5362 
init_prog_array_slots(struct bpf_object * obj,struct bpf_map * map)5363 static int init_prog_array_slots(struct bpf_object *obj, struct bpf_map *map)
5364 {
5365 	const struct bpf_program *targ_prog;
5366 	unsigned int i;
5367 	int fd, err;
5368 
5369 	if (obj->gen_loader)
5370 		return -ENOTSUP;
5371 
5372 	for (i = 0; i < map->init_slots_sz; i++) {
5373 		if (!map->init_slots[i])
5374 			continue;
5375 
5376 		targ_prog = map->init_slots[i];
5377 		fd = bpf_program__fd(targ_prog);
5378 
5379 		err = bpf_map_update_elem(map->fd, &i, &fd, 0);
5380 		if (err) {
5381 			err = -errno;
5382 			pr_warn("map '%s': failed to initialize slot [%d] to prog '%s' fd=%d: %s\n",
5383 				map->name, i, targ_prog->name, fd, errstr(err));
5384 			return err;
5385 		}
5386 		pr_debug("map '%s': slot [%d] set to prog '%s' fd=%d\n",
5387 			 map->name, i, targ_prog->name, fd);
5388 	}
5389 
5390 	zfree(&map->init_slots);
5391 	map->init_slots_sz = 0;
5392 
5393 	return 0;
5394 }
5395 
bpf_object_init_prog_arrays(struct bpf_object * obj)5396 static int bpf_object_init_prog_arrays(struct bpf_object *obj)
5397 {
5398 	struct bpf_map *map;
5399 	int i, err;
5400 
5401 	for (i = 0; i < obj->nr_maps; i++) {
5402 		map = &obj->maps[i];
5403 
5404 		if (!map->init_slots_sz || map->def.type != BPF_MAP_TYPE_PROG_ARRAY)
5405 			continue;
5406 
5407 		err = init_prog_array_slots(obj, map);
5408 		if (err < 0)
5409 			return err;
5410 	}
5411 	return 0;
5412 }
5413 
map_set_def_max_entries(struct bpf_map * map)5414 static int map_set_def_max_entries(struct bpf_map *map)
5415 {
5416 	if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries) {
5417 		int nr_cpus;
5418 
5419 		nr_cpus = libbpf_num_possible_cpus();
5420 		if (nr_cpus < 0) {
5421 			pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
5422 				map->name, nr_cpus);
5423 			return nr_cpus;
5424 		}
5425 		pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
5426 		map->def.max_entries = nr_cpus;
5427 	}
5428 
5429 	return 0;
5430 }
5431 
5432 static int
bpf_object__create_maps(struct bpf_object * obj)5433 bpf_object__create_maps(struct bpf_object *obj)
5434 {
5435 	struct bpf_map *map;
5436 	unsigned int i, j;
5437 	int err;
5438 	bool retried;
5439 
5440 	for (i = 0; i < obj->nr_maps; i++) {
5441 		map = &obj->maps[i];
5442 
5443 		/* To support old kernels, we skip creating global data maps
5444 		 * (.rodata, .data, .kconfig, etc); later on, during program
5445 		 * loading, if we detect that at least one of the to-be-loaded
5446 		 * programs is referencing any global data map, we'll error
5447 		 * out with program name and relocation index logged.
5448 		 * This approach allows to accommodate Clang emitting
5449 		 * unnecessary .rodata.str1.1 sections for string literals,
5450 		 * but also it allows to have CO-RE applications that use
5451 		 * global variables in some of BPF programs, but not others.
5452 		 * If those global variable-using programs are not loaded at
5453 		 * runtime due to bpf_program__set_autoload(prog, false),
5454 		 * bpf_object loading will succeed just fine even on old
5455 		 * kernels.
5456 		 */
5457 		if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
5458 			map->autocreate = false;
5459 
5460 		if (!map->autocreate) {
5461 			pr_debug("map '%s': skipped auto-creating...\n", map->name);
5462 			continue;
5463 		}
5464 
5465 		err = map_set_def_max_entries(map);
5466 		if (err)
5467 			goto err_out;
5468 
5469 		retried = false;
5470 retry:
5471 		if (map->pin_path) {
5472 			err = bpf_object__reuse_map(map);
5473 			if (err) {
5474 				pr_warn("map '%s': error reusing pinned map\n",
5475 					map->name);
5476 				goto err_out;
5477 			}
5478 			if (retried && map->fd < 0) {
5479 				pr_warn("map '%s': cannot find pinned map\n",
5480 					map->name);
5481 				err = -ENOENT;
5482 				goto err_out;
5483 			}
5484 		}
5485 
5486 		if (map->reused) {
5487 			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
5488 				 map->name, map->fd);
5489 		} else {
5490 			err = bpf_object__create_map(obj, map, false);
5491 			if (err)
5492 				goto err_out;
5493 
5494 			pr_debug("map '%s': created successfully, fd=%d\n",
5495 				 map->name, map->fd);
5496 
5497 			if (bpf_map__is_internal(map)) {
5498 				err = bpf_object__populate_internal_map(obj, map);
5499 				if (err < 0)
5500 					goto err_out;
5501 			} else if (map->def.type == BPF_MAP_TYPE_ARENA) {
5502 				map->mmaped = mmap((void *)(long)map->map_extra,
5503 						   bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
5504 						   map->map_extra ? MAP_SHARED | MAP_FIXED : MAP_SHARED,
5505 						   map->fd, 0);
5506 				if (map->mmaped == MAP_FAILED) {
5507 					err = -errno;
5508 					map->mmaped = NULL;
5509 					pr_warn("map '%s': failed to mmap arena: %s\n",
5510 						map->name, errstr(err));
5511 					return err;
5512 				}
5513 				if (obj->arena_data) {
5514 					memcpy(map->mmaped, obj->arena_data, obj->arena_data_sz);
5515 					zfree(&obj->arena_data);
5516 				}
5517 			}
5518 			if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
5519 				err = init_map_in_map_slots(obj, map);
5520 				if (err < 0)
5521 					goto err_out;
5522 			}
5523 		}
5524 
5525 		if (map->pin_path && !map->pinned) {
5526 			err = bpf_map__pin(map, NULL);
5527 			if (err) {
5528 				if (!retried && err == -EEXIST) {
5529 					retried = true;
5530 					goto retry;
5531 				}
5532 				pr_warn("map '%s': failed to auto-pin at '%s': %s\n",
5533 					map->name, map->pin_path, errstr(err));
5534 				goto err_out;
5535 			}
5536 		}
5537 	}
5538 
5539 	return 0;
5540 
5541 err_out:
5542 	pr_warn("map '%s': failed to create: %s\n", map->name, errstr(err));
5543 	pr_perm_msg(err);
5544 	for (j = 0; j < i; j++)
5545 		zclose(obj->maps[j].fd);
5546 	return err;
5547 }
5548 
bpf_core_is_flavor_sep(const char * s)5549 static bool bpf_core_is_flavor_sep(const char *s)
5550 {
5551 	/* check X___Y name pattern, where X and Y are not underscores */
5552 	return s[0] != '_' &&				      /* X */
5553 	       s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
5554 	       s[4] != '_';				      /* Y */
5555 }
5556 
5557 /* Given 'some_struct_name___with_flavor' return the length of a name prefix
5558  * before last triple underscore. Struct name part after last triple
5559  * underscore is ignored by BPF CO-RE relocation during relocation matching.
5560  */
bpf_core_essential_name_len(const char * name)5561 size_t bpf_core_essential_name_len(const char *name)
5562 {
5563 	size_t n = strlen(name);
5564 	int i;
5565 
5566 	for (i = n - 5; i >= 0; i--) {
5567 		if (bpf_core_is_flavor_sep(name + i))
5568 			return i + 1;
5569 	}
5570 	return n;
5571 }
5572 
bpf_core_free_cands(struct bpf_core_cand_list * cands)5573 void bpf_core_free_cands(struct bpf_core_cand_list *cands)
5574 {
5575 	if (!cands)
5576 		return;
5577 
5578 	free(cands->cands);
5579 	free(cands);
5580 }
5581 
bpf_core_add_cands(struct bpf_core_cand * local_cand,size_t local_essent_len,const struct btf * targ_btf,const char * targ_btf_name,int targ_start_id,struct bpf_core_cand_list * cands)5582 int bpf_core_add_cands(struct bpf_core_cand *local_cand,
5583 		       size_t local_essent_len,
5584 		       const struct btf *targ_btf,
5585 		       const char *targ_btf_name,
5586 		       int targ_start_id,
5587 		       struct bpf_core_cand_list *cands)
5588 {
5589 	struct bpf_core_cand *new_cands, *cand;
5590 	const struct btf_type *t, *local_t;
5591 	const char *targ_name, *local_name;
5592 	size_t targ_essent_len;
5593 	int n, i;
5594 
5595 	local_t = btf__type_by_id(local_cand->btf, local_cand->id);
5596 	local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
5597 
5598 	n = btf__type_cnt(targ_btf);
5599 	for (i = targ_start_id; i < n; i++) {
5600 		t = btf__type_by_id(targ_btf, i);
5601 		if (!btf_kind_core_compat(t, local_t))
5602 			continue;
5603 
5604 		targ_name = btf__name_by_offset(targ_btf, t->name_off);
5605 		if (str_is_empty(targ_name))
5606 			continue;
5607 
5608 		targ_essent_len = bpf_core_essential_name_len(targ_name);
5609 		if (targ_essent_len != local_essent_len)
5610 			continue;
5611 
5612 		if (strncmp(local_name, targ_name, local_essent_len) != 0)
5613 			continue;
5614 
5615 		pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
5616 			 local_cand->id, btf_kind_str(local_t),
5617 			 local_name, i, btf_kind_str(t), targ_name,
5618 			 targ_btf_name);
5619 		new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
5620 					      sizeof(*cands->cands));
5621 		if (!new_cands)
5622 			return -ENOMEM;
5623 
5624 		cand = &new_cands[cands->len];
5625 		cand->btf = targ_btf;
5626 		cand->id = i;
5627 
5628 		cands->cands = new_cands;
5629 		cands->len++;
5630 	}
5631 	return 0;
5632 }
5633 
load_module_btfs(struct bpf_object * obj)5634 static int load_module_btfs(struct bpf_object *obj)
5635 {
5636 	struct bpf_btf_info info;
5637 	struct module_btf *mod_btf;
5638 	struct btf *btf;
5639 	char name[64];
5640 	__u32 id = 0, len;
5641 	int err, fd;
5642 
5643 	if (obj->btf_modules_loaded)
5644 		return 0;
5645 
5646 	if (obj->gen_loader)
5647 		return 0;
5648 
5649 	/* don't do this again, even if we find no module BTFs */
5650 	obj->btf_modules_loaded = true;
5651 
5652 	/* kernel too old to support module BTFs */
5653 	if (!kernel_supports(obj, FEAT_MODULE_BTF))
5654 		return 0;
5655 
5656 	while (true) {
5657 		err = bpf_btf_get_next_id(id, &id);
5658 		if (err && errno == ENOENT)
5659 			return 0;
5660 		if (err && errno == EPERM) {
5661 			pr_debug("skipping module BTFs loading, missing privileges\n");
5662 			return 0;
5663 		}
5664 		if (err) {
5665 			err = -errno;
5666 			pr_warn("failed to iterate BTF objects: %s\n", errstr(err));
5667 			return err;
5668 		}
5669 
5670 		fd = bpf_btf_get_fd_by_id(id);
5671 		if (fd < 0) {
5672 			if (errno == ENOENT)
5673 				continue; /* expected race: BTF was unloaded */
5674 			err = -errno;
5675 			pr_warn("failed to get BTF object #%d FD: %s\n", id, errstr(err));
5676 			return err;
5677 		}
5678 
5679 		len = sizeof(info);
5680 		memset(&info, 0, sizeof(info));
5681 		info.name = ptr_to_u64(name);
5682 		info.name_len = sizeof(name);
5683 
5684 		err = bpf_btf_get_info_by_fd(fd, &info, &len);
5685 		if (err) {
5686 			err = -errno;
5687 			pr_warn("failed to get BTF object #%d info: %s\n", id, errstr(err));
5688 			goto err_out;
5689 		}
5690 
5691 		/* ignore non-module BTFs */
5692 		if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
5693 			close(fd);
5694 			continue;
5695 		}
5696 
5697 		btf = btf_get_from_fd(fd, obj->btf_vmlinux);
5698 		err = libbpf_get_error(btf);
5699 		if (err) {
5700 			pr_warn("failed to load module [%s]'s BTF object #%d: %s\n",
5701 				name, id, errstr(err));
5702 			goto err_out;
5703 		}
5704 
5705 		err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
5706 					sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
5707 		if (err)
5708 			goto err_out;
5709 
5710 		mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
5711 
5712 		mod_btf->btf = btf;
5713 		mod_btf->id = id;
5714 		mod_btf->fd = fd;
5715 		mod_btf->name = strdup(name);
5716 		if (!mod_btf->name) {
5717 			err = -ENOMEM;
5718 			goto err_out;
5719 		}
5720 		continue;
5721 
5722 err_out:
5723 		close(fd);
5724 		return err;
5725 	}
5726 
5727 	return 0;
5728 }
5729 
5730 static struct bpf_core_cand_list *
bpf_core_find_cands(struct bpf_object * obj,const struct btf * local_btf,__u32 local_type_id)5731 bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
5732 {
5733 	struct bpf_core_cand local_cand = {};
5734 	struct bpf_core_cand_list *cands;
5735 	const struct btf *main_btf;
5736 	const struct btf_type *local_t;
5737 	const char *local_name;
5738 	size_t local_essent_len;
5739 	int err, i;
5740 
5741 	local_cand.btf = local_btf;
5742 	local_cand.id = local_type_id;
5743 	local_t = btf__type_by_id(local_btf, local_type_id);
5744 	if (!local_t)
5745 		return ERR_PTR(-EINVAL);
5746 
5747 	local_name = btf__name_by_offset(local_btf, local_t->name_off);
5748 	if (str_is_empty(local_name))
5749 		return ERR_PTR(-EINVAL);
5750 	local_essent_len = bpf_core_essential_name_len(local_name);
5751 
5752 	cands = calloc(1, sizeof(*cands));
5753 	if (!cands)
5754 		return ERR_PTR(-ENOMEM);
5755 
5756 	/* Attempt to find target candidates in vmlinux BTF first */
5757 	main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
5758 	err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
5759 	if (err)
5760 		goto err_out;
5761 
5762 	/* if vmlinux BTF has any candidate, don't got for module BTFs */
5763 	if (cands->len)
5764 		return cands;
5765 
5766 	/* if vmlinux BTF was overridden, don't attempt to load module BTFs */
5767 	if (obj->btf_vmlinux_override)
5768 		return cands;
5769 
5770 	/* now look through module BTFs, trying to still find candidates */
5771 	err = load_module_btfs(obj);
5772 	if (err)
5773 		goto err_out;
5774 
5775 	for (i = 0; i < obj->btf_module_cnt; i++) {
5776 		err = bpf_core_add_cands(&local_cand, local_essent_len,
5777 					 obj->btf_modules[i].btf,
5778 					 obj->btf_modules[i].name,
5779 					 btf__type_cnt(obj->btf_vmlinux),
5780 					 cands);
5781 		if (err)
5782 			goto err_out;
5783 	}
5784 
5785 	return cands;
5786 err_out:
5787 	bpf_core_free_cands(cands);
5788 	return ERR_PTR(err);
5789 }
5790 
5791 /* Check local and target types for compatibility. This check is used for
5792  * type-based CO-RE relocations and follow slightly different rules than
5793  * field-based relocations. This function assumes that root types were already
5794  * checked for name match. Beyond that initial root-level name check, names
5795  * are completely ignored. Compatibility rules are as follows:
5796  *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
5797  *     kind should match for local and target types (i.e., STRUCT is not
5798  *     compatible with UNION);
5799  *   - for ENUMs, the size is ignored;
5800  *   - for INT, size and signedness are ignored;
5801  *   - for ARRAY, dimensionality is ignored, element types are checked for
5802  *     compatibility recursively;
5803  *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
5804  *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
5805  *   - FUNC_PROTOs are compatible if they have compatible signature: same
5806  *     number of input args and compatible return and argument types.
5807  * These rules are not set in stone and probably will be adjusted as we get
5808  * more experience with using BPF CO-RE relocations.
5809  */
bpf_core_types_are_compat(const struct btf * local_btf,__u32 local_id,const struct btf * targ_btf,__u32 targ_id)5810 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
5811 			      const struct btf *targ_btf, __u32 targ_id)
5812 {
5813 	return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
5814 }
5815 
bpf_core_types_match(const struct btf * local_btf,__u32 local_id,const struct btf * targ_btf,__u32 targ_id)5816 int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
5817 			 const struct btf *targ_btf, __u32 targ_id)
5818 {
5819 	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
5820 }
5821 
bpf_core_hash_fn(const long key,void * ctx)5822 static size_t bpf_core_hash_fn(const long key, void *ctx)
5823 {
5824 	return key;
5825 }
5826 
bpf_core_equal_fn(const long k1,const long k2,void * ctx)5827 static bool bpf_core_equal_fn(const long k1, const long k2, void *ctx)
5828 {
5829 	return k1 == k2;
5830 }
5831 
record_relo_core(struct bpf_program * prog,const struct bpf_core_relo * core_relo,int insn_idx)5832 static int record_relo_core(struct bpf_program *prog,
5833 			    const struct bpf_core_relo *core_relo, int insn_idx)
5834 {
5835 	struct reloc_desc *relos, *relo;
5836 
5837 	relos = libbpf_reallocarray(prog->reloc_desc,
5838 				    prog->nr_reloc + 1, sizeof(*relos));
5839 	if (!relos)
5840 		return -ENOMEM;
5841 	relo = &relos[prog->nr_reloc];
5842 	relo->type = RELO_CORE;
5843 	relo->insn_idx = insn_idx;
5844 	relo->core_relo = core_relo;
5845 	prog->reloc_desc = relos;
5846 	prog->nr_reloc++;
5847 	return 0;
5848 }
5849 
find_relo_core(struct bpf_program * prog,int insn_idx)5850 static const struct bpf_core_relo *find_relo_core(struct bpf_program *prog, int insn_idx)
5851 {
5852 	struct reloc_desc *relo;
5853 	int i;
5854 
5855 	for (i = 0; i < prog->nr_reloc; i++) {
5856 		relo = &prog->reloc_desc[i];
5857 		if (relo->type != RELO_CORE || relo->insn_idx != insn_idx)
5858 			continue;
5859 
5860 		return relo->core_relo;
5861 	}
5862 
5863 	return NULL;
5864 }
5865 
bpf_core_resolve_relo(struct bpf_program * prog,const struct bpf_core_relo * relo,int relo_idx,const struct btf * local_btf,struct hashmap * cand_cache,struct bpf_core_relo_res * targ_res)5866 static int bpf_core_resolve_relo(struct bpf_program *prog,
5867 				 const struct bpf_core_relo *relo,
5868 				 int relo_idx,
5869 				 const struct btf *local_btf,
5870 				 struct hashmap *cand_cache,
5871 				 struct bpf_core_relo_res *targ_res)
5872 {
5873 	struct bpf_core_spec specs_scratch[3] = {};
5874 	struct bpf_core_cand_list *cands = NULL;
5875 	const char *prog_name = prog->name;
5876 	const struct btf_type *local_type;
5877 	const char *local_name;
5878 	__u32 local_id = relo->type_id;
5879 	int err;
5880 
5881 	local_type = btf__type_by_id(local_btf, local_id);
5882 	if (!local_type)
5883 		return -EINVAL;
5884 
5885 	local_name = btf__name_by_offset(local_btf, local_type->name_off);
5886 	if (!local_name)
5887 		return -EINVAL;
5888 
5889 	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
5890 	    !hashmap__find(cand_cache, local_id, &cands)) {
5891 		cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
5892 		if (IS_ERR(cands)) {
5893 			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
5894 				prog_name, relo_idx, local_id, btf_kind_str(local_type),
5895 				local_name, PTR_ERR(cands));
5896 			return PTR_ERR(cands);
5897 		}
5898 		err = hashmap__set(cand_cache, local_id, cands, NULL, NULL);
5899 		if (err) {
5900 			bpf_core_free_cands(cands);
5901 			return err;
5902 		}
5903 	}
5904 
5905 	return bpf_core_calc_relo_insn(prog_name, relo, relo_idx, local_btf, cands, specs_scratch,
5906 				       targ_res);
5907 }
5908 
5909 static int
bpf_object__relocate_core(struct bpf_object * obj,const char * targ_btf_path)5910 bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
5911 {
5912 	const struct btf_ext_info_sec *sec;
5913 	struct bpf_core_relo_res targ_res;
5914 	const struct bpf_core_relo *rec;
5915 	const struct btf_ext_info *seg;
5916 	struct hashmap_entry *entry;
5917 	struct hashmap *cand_cache = NULL;
5918 	struct bpf_program *prog;
5919 	struct bpf_insn *insn;
5920 	const char *sec_name;
5921 	int i, err = 0, insn_idx, sec_idx, sec_num;
5922 
5923 	if (obj->btf_ext->core_relo_info.len == 0)
5924 		return 0;
5925 
5926 	if (targ_btf_path) {
5927 		obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
5928 		err = libbpf_get_error(obj->btf_vmlinux_override);
5929 		if (err) {
5930 			pr_warn("failed to parse target BTF: %s\n", errstr(err));
5931 			return err;
5932 		}
5933 	}
5934 
5935 	cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
5936 	if (IS_ERR(cand_cache)) {
5937 		err = PTR_ERR(cand_cache);
5938 		goto out;
5939 	}
5940 
5941 	seg = &obj->btf_ext->core_relo_info;
5942 	sec_num = 0;
5943 	for_each_btf_ext_sec(seg, sec) {
5944 		sec_idx = seg->sec_idxs[sec_num];
5945 		sec_num++;
5946 
5947 		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
5948 		if (str_is_empty(sec_name)) {
5949 			err = -EINVAL;
5950 			goto out;
5951 		}
5952 
5953 		pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info);
5954 
5955 		for_each_btf_ext_rec(seg, sec, i, rec) {
5956 			if (rec->insn_off % BPF_INSN_SZ)
5957 				return -EINVAL;
5958 			insn_idx = rec->insn_off / BPF_INSN_SZ;
5959 			prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
5960 			if (!prog) {
5961 				/* When __weak subprog is "overridden" by another instance
5962 				 * of the subprog from a different object file, linker still
5963 				 * appends all the .BTF.ext info that used to belong to that
5964 				 * eliminated subprogram.
5965 				 * This is similar to what x86-64 linker does for relocations.
5966 				 * So just ignore such relocations just like we ignore
5967 				 * subprog instructions when discovering subprograms.
5968 				 */
5969 				pr_debug("sec '%s': skipping CO-RE relocation #%d for insn #%d belonging to eliminated weak subprogram\n",
5970 					 sec_name, i, insn_idx);
5971 				continue;
5972 			}
5973 			/* no need to apply CO-RE relocation if the program is
5974 			 * not going to be loaded
5975 			 */
5976 			if (!prog->autoload)
5977 				continue;
5978 
5979 			/* adjust insn_idx from section frame of reference to the local
5980 			 * program's frame of reference; (sub-)program code is not yet
5981 			 * relocated, so it's enough to just subtract in-section offset
5982 			 */
5983 			insn_idx = insn_idx - prog->sec_insn_off;
5984 			if (insn_idx >= prog->insns_cnt)
5985 				return -EINVAL;
5986 			insn = &prog->insns[insn_idx];
5987 
5988 			err = record_relo_core(prog, rec, insn_idx);
5989 			if (err) {
5990 				pr_warn("prog '%s': relo #%d: failed to record relocation: %s\n",
5991 					prog->name, i, errstr(err));
5992 				goto out;
5993 			}
5994 
5995 			if (prog->obj->gen_loader)
5996 				continue;
5997 
5998 			err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res);
5999 			if (err) {
6000 				pr_warn("prog '%s': relo #%d: failed to relocate: %s\n",
6001 					prog->name, i, errstr(err));
6002 				goto out;
6003 			}
6004 
6005 			err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
6006 			if (err) {
6007 				pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %s\n",
6008 					prog->name, i, insn_idx, errstr(err));
6009 				goto out;
6010 			}
6011 		}
6012 	}
6013 
6014 out:
6015 	/* obj->btf_vmlinux and module BTFs are freed after object load */
6016 	btf__free(obj->btf_vmlinux_override);
6017 	obj->btf_vmlinux_override = NULL;
6018 
6019 	if (!IS_ERR_OR_NULL(cand_cache)) {
6020 		hashmap__for_each_entry(cand_cache, entry, i) {
6021 			bpf_core_free_cands(entry->pvalue);
6022 		}
6023 		hashmap__free(cand_cache);
6024 	}
6025 	return err;
6026 }
6027 
6028 /* base map load ldimm64 special constant, used also for log fixup logic */
6029 #define POISON_LDIMM64_MAP_BASE 2001000000
6030 #define POISON_LDIMM64_MAP_PFX "200100"
6031 
poison_map_ldimm64(struct bpf_program * prog,int relo_idx,int insn_idx,struct bpf_insn * insn,int map_idx,const struct bpf_map * map)6032 static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
6033 			       int insn_idx, struct bpf_insn *insn,
6034 			       int map_idx, const struct bpf_map *map)
6035 {
6036 	int i;
6037 
6038 	pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
6039 		 prog->name, relo_idx, insn_idx, map_idx, map->name);
6040 
6041 	/* we turn single ldimm64 into two identical invalid calls */
6042 	for (i = 0; i < 2; i++) {
6043 		insn->code = BPF_JMP | BPF_CALL;
6044 		insn->dst_reg = 0;
6045 		insn->src_reg = 0;
6046 		insn->off = 0;
6047 		/* if this instruction is reachable (not a dead code),
6048 		 * verifier will complain with something like:
6049 		 * invalid func unknown#2001000123
6050 		 * where lower 123 is map index into obj->maps[] array
6051 		 */
6052 		insn->imm = POISON_LDIMM64_MAP_BASE + map_idx;
6053 
6054 		insn++;
6055 	}
6056 }
6057 
6058 /* unresolved kfunc call special constant, used also for log fixup logic */
6059 #define POISON_CALL_KFUNC_BASE 2002000000
6060 #define POISON_CALL_KFUNC_PFX "2002"
6061 
poison_kfunc_call(struct bpf_program * prog,int relo_idx,int insn_idx,struct bpf_insn * insn,int ext_idx,const struct extern_desc * ext)6062 static void poison_kfunc_call(struct bpf_program *prog, int relo_idx,
6063 			      int insn_idx, struct bpf_insn *insn,
6064 			      int ext_idx, const struct extern_desc *ext)
6065 {
6066 	pr_debug("prog '%s': relo #%d: poisoning insn #%d that calls kfunc '%s'\n",
6067 		 prog->name, relo_idx, insn_idx, ext->name);
6068 
6069 	/* we turn kfunc call into invalid helper call with identifiable constant */
6070 	insn->code = BPF_JMP | BPF_CALL;
6071 	insn->dst_reg = 0;
6072 	insn->src_reg = 0;
6073 	insn->off = 0;
6074 	/* if this instruction is reachable (not a dead code),
6075 	 * verifier will complain with something like:
6076 	 * invalid func unknown#2001000123
6077 	 * where lower 123 is extern index into obj->externs[] array
6078 	 */
6079 	insn->imm = POISON_CALL_KFUNC_BASE + ext_idx;
6080 }
6081 
6082 /* Relocate data references within program code:
6083  *  - map references;
6084  *  - global variable references;
6085  *  - extern references.
6086  */
6087 static int
bpf_object__relocate_data(struct bpf_object * obj,struct bpf_program * prog)6088 bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
6089 {
6090 	int i;
6091 
6092 	for (i = 0; i < prog->nr_reloc; i++) {
6093 		struct reloc_desc *relo = &prog->reloc_desc[i];
6094 		struct bpf_insn *insn = &prog->insns[relo->insn_idx];
6095 		const struct bpf_map *map;
6096 		struct extern_desc *ext;
6097 
6098 		switch (relo->type) {
6099 		case RELO_LD64:
6100 			map = &obj->maps[relo->map_idx];
6101 			if (obj->gen_loader) {
6102 				insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
6103 				insn[0].imm = relo->map_idx;
6104 			} else if (map->autocreate) {
6105 				insn[0].src_reg = BPF_PSEUDO_MAP_FD;
6106 				insn[0].imm = map->fd;
6107 			} else {
6108 				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
6109 						   relo->map_idx, map);
6110 			}
6111 			break;
6112 		case RELO_DATA:
6113 			map = &obj->maps[relo->map_idx];
6114 			insn[1].imm = insn[0].imm + relo->sym_off;
6115 			if (obj->gen_loader) {
6116 				insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
6117 				insn[0].imm = relo->map_idx;
6118 			} else if (map->autocreate) {
6119 				insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
6120 				insn[0].imm = map->fd;
6121 			} else {
6122 				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
6123 						   relo->map_idx, map);
6124 			}
6125 			break;
6126 		case RELO_EXTERN_LD64:
6127 			ext = &obj->externs[relo->ext_idx];
6128 			if (ext->type == EXT_KCFG) {
6129 				if (obj->gen_loader) {
6130 					insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
6131 					insn[0].imm = obj->kconfig_map_idx;
6132 				} else {
6133 					insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
6134 					insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
6135 				}
6136 				insn[1].imm = ext->kcfg.data_off;
6137 			} else /* EXT_KSYM */ {
6138 				if (ext->ksym.type_id && ext->is_set) { /* typed ksyms */
6139 					insn[0].src_reg = BPF_PSEUDO_BTF_ID;
6140 					insn[0].imm = ext->ksym.kernel_btf_id;
6141 					insn[1].imm = ext->ksym.kernel_btf_obj_fd;
6142 				} else { /* typeless ksyms or unresolved typed ksyms */
6143 					insn[0].imm = (__u32)ext->ksym.addr;
6144 					insn[1].imm = ext->ksym.addr >> 32;
6145 				}
6146 			}
6147 			break;
6148 		case RELO_EXTERN_CALL:
6149 			ext = &obj->externs[relo->ext_idx];
6150 			insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
6151 			if (ext->is_set) {
6152 				insn[0].imm = ext->ksym.kernel_btf_id;
6153 				insn[0].off = ext->ksym.btf_fd_idx;
6154 			} else { /* unresolved weak kfunc call */
6155 				poison_kfunc_call(prog, i, relo->insn_idx, insn,
6156 						  relo->ext_idx, ext);
6157 			}
6158 			break;
6159 		case RELO_SUBPROG_ADDR:
6160 			if (insn[0].src_reg != BPF_PSEUDO_FUNC) {
6161 				pr_warn("prog '%s': relo #%d: bad insn\n",
6162 					prog->name, i);
6163 				return -EINVAL;
6164 			}
6165 			/* handled already */
6166 			break;
6167 		case RELO_CALL:
6168 			/* handled already */
6169 			break;
6170 		case RELO_CORE:
6171 			/* will be handled by bpf_program_record_relos() */
6172 			break;
6173 		default:
6174 			pr_warn("prog '%s': relo #%d: bad relo type %d\n",
6175 				prog->name, i, relo->type);
6176 			return -EINVAL;
6177 		}
6178 	}
6179 
6180 	return 0;
6181 }
6182 
adjust_prog_btf_ext_info(const struct bpf_object * obj,const struct bpf_program * prog,const struct btf_ext_info * ext_info,void ** prog_info,__u32 * prog_rec_cnt,__u32 * prog_rec_sz)6183 static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
6184 				    const struct bpf_program *prog,
6185 				    const struct btf_ext_info *ext_info,
6186 				    void **prog_info, __u32 *prog_rec_cnt,
6187 				    __u32 *prog_rec_sz)
6188 {
6189 	void *copy_start = NULL, *copy_end = NULL;
6190 	void *rec, *rec_end, *new_prog_info;
6191 	const struct btf_ext_info_sec *sec;
6192 	size_t old_sz, new_sz;
6193 	int i, sec_num, sec_idx, off_adj;
6194 
6195 	sec_num = 0;
6196 	for_each_btf_ext_sec(ext_info, sec) {
6197 		sec_idx = ext_info->sec_idxs[sec_num];
6198 		sec_num++;
6199 		if (prog->sec_idx != sec_idx)
6200 			continue;
6201 
6202 		for_each_btf_ext_rec(ext_info, sec, i, rec) {
6203 			__u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
6204 
6205 			if (insn_off < prog->sec_insn_off)
6206 				continue;
6207 			if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
6208 				break;
6209 
6210 			if (!copy_start)
6211 				copy_start = rec;
6212 			copy_end = rec + ext_info->rec_size;
6213 		}
6214 
6215 		if (!copy_start)
6216 			return -ENOENT;
6217 
6218 		/* append func/line info of a given (sub-)program to the main
6219 		 * program func/line info
6220 		 */
6221 		old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
6222 		new_sz = old_sz + (copy_end - copy_start);
6223 		new_prog_info = realloc(*prog_info, new_sz);
6224 		if (!new_prog_info)
6225 			return -ENOMEM;
6226 		*prog_info = new_prog_info;
6227 		*prog_rec_cnt = new_sz / ext_info->rec_size;
6228 		memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
6229 
6230 		/* Kernel instruction offsets are in units of 8-byte
6231 		 * instructions, while .BTF.ext instruction offsets generated
6232 		 * by Clang are in units of bytes. So convert Clang offsets
6233 		 * into kernel offsets and adjust offset according to program
6234 		 * relocated position.
6235 		 */
6236 		off_adj = prog->sub_insn_off - prog->sec_insn_off;
6237 		rec = new_prog_info + old_sz;
6238 		rec_end = new_prog_info + new_sz;
6239 		for (; rec < rec_end; rec += ext_info->rec_size) {
6240 			__u32 *insn_off = rec;
6241 
6242 			*insn_off = *insn_off / BPF_INSN_SZ + off_adj;
6243 		}
6244 		*prog_rec_sz = ext_info->rec_size;
6245 		return 0;
6246 	}
6247 
6248 	return -ENOENT;
6249 }
6250 
6251 static int
reloc_prog_func_and_line_info(const struct bpf_object * obj,struct bpf_program * main_prog,const struct bpf_program * prog)6252 reloc_prog_func_and_line_info(const struct bpf_object *obj,
6253 			      struct bpf_program *main_prog,
6254 			      const struct bpf_program *prog)
6255 {
6256 	int err;
6257 
6258 	/* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
6259 	 * support func/line info
6260 	 */
6261 	if (!obj->btf_ext || !kernel_supports(obj, FEAT_BTF_FUNC))
6262 		return 0;
6263 
6264 	/* only attempt func info relocation if main program's func_info
6265 	 * relocation was successful
6266 	 */
6267 	if (main_prog != prog && !main_prog->func_info)
6268 		goto line_info;
6269 
6270 	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
6271 				       &main_prog->func_info,
6272 				       &main_prog->func_info_cnt,
6273 				       &main_prog->func_info_rec_size);
6274 	if (err) {
6275 		if (err != -ENOENT) {
6276 			pr_warn("prog '%s': error relocating .BTF.ext function info: %s\n",
6277 				prog->name, errstr(err));
6278 			return err;
6279 		}
6280 		if (main_prog->func_info) {
6281 			/*
6282 			 * Some info has already been found but has problem
6283 			 * in the last btf_ext reloc. Must have to error out.
6284 			 */
6285 			pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
6286 			return err;
6287 		}
6288 		/* Have problem loading the very first info. Ignore the rest. */
6289 		pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
6290 			prog->name);
6291 	}
6292 
6293 line_info:
6294 	/* don't relocate line info if main program's relocation failed */
6295 	if (main_prog != prog && !main_prog->line_info)
6296 		return 0;
6297 
6298 	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
6299 				       &main_prog->line_info,
6300 				       &main_prog->line_info_cnt,
6301 				       &main_prog->line_info_rec_size);
6302 	if (err) {
6303 		if (err != -ENOENT) {
6304 			pr_warn("prog '%s': error relocating .BTF.ext line info: %s\n",
6305 				prog->name, errstr(err));
6306 			return err;
6307 		}
6308 		if (main_prog->line_info) {
6309 			/*
6310 			 * Some info has already been found but has problem
6311 			 * in the last btf_ext reloc. Must have to error out.
6312 			 */
6313 			pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
6314 			return err;
6315 		}
6316 		/* Have problem loading the very first info. Ignore the rest. */
6317 		pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
6318 			prog->name);
6319 	}
6320 	return 0;
6321 }
6322 
cmp_relo_by_insn_idx(const void * key,const void * elem)6323 static int cmp_relo_by_insn_idx(const void *key, const void *elem)
6324 {
6325 	size_t insn_idx = *(const size_t *)key;
6326 	const struct reloc_desc *relo = elem;
6327 
6328 	if (insn_idx == relo->insn_idx)
6329 		return 0;
6330 	return insn_idx < relo->insn_idx ? -1 : 1;
6331 }
6332 
find_prog_insn_relo(const struct bpf_program * prog,size_t insn_idx)6333 static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
6334 {
6335 	if (!prog->nr_reloc)
6336 		return NULL;
6337 	return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
6338 		       sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
6339 }
6340 
append_subprog_relos(struct bpf_program * main_prog,struct bpf_program * subprog)6341 static int append_subprog_relos(struct bpf_program *main_prog, struct bpf_program *subprog)
6342 {
6343 	int new_cnt = main_prog->nr_reloc + subprog->nr_reloc;
6344 	struct reloc_desc *relos;
6345 	int i;
6346 
6347 	if (main_prog == subprog)
6348 		return 0;
6349 	relos = libbpf_reallocarray(main_prog->reloc_desc, new_cnt, sizeof(*relos));
6350 	/* if new count is zero, reallocarray can return a valid NULL result;
6351 	 * in this case the previous pointer will be freed, so we *have to*
6352 	 * reassign old pointer to the new value (even if it's NULL)
6353 	 */
6354 	if (!relos && new_cnt)
6355 		return -ENOMEM;
6356 	if (subprog->nr_reloc)
6357 		memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc,
6358 		       sizeof(*relos) * subprog->nr_reloc);
6359 
6360 	for (i = main_prog->nr_reloc; i < new_cnt; i++)
6361 		relos[i].insn_idx += subprog->sub_insn_off;
6362 	/* After insn_idx adjustment the 'relos' array is still sorted
6363 	 * by insn_idx and doesn't break bsearch.
6364 	 */
6365 	main_prog->reloc_desc = relos;
6366 	main_prog->nr_reloc = new_cnt;
6367 	return 0;
6368 }
6369 
6370 static int
bpf_object__append_subprog_code(struct bpf_object * obj,struct bpf_program * main_prog,struct bpf_program * subprog)6371 bpf_object__append_subprog_code(struct bpf_object *obj, struct bpf_program *main_prog,
6372 				struct bpf_program *subprog)
6373 {
6374        struct bpf_insn *insns;
6375        size_t new_cnt;
6376        int err;
6377 
6378        subprog->sub_insn_off = main_prog->insns_cnt;
6379 
6380        new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
6381        insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
6382        if (!insns) {
6383                pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
6384                return -ENOMEM;
6385        }
6386        main_prog->insns = insns;
6387        main_prog->insns_cnt = new_cnt;
6388 
6389        memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
6390               subprog->insns_cnt * sizeof(*insns));
6391 
6392        pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
6393                 main_prog->name, subprog->insns_cnt, subprog->name);
6394 
6395        /* The subprog insns are now appended. Append its relos too. */
6396        err = append_subprog_relos(main_prog, subprog);
6397        if (err)
6398                return err;
6399        return 0;
6400 }
6401 
6402 static int
bpf_object__reloc_code(struct bpf_object * obj,struct bpf_program * main_prog,struct bpf_program * prog)6403 bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
6404 		       struct bpf_program *prog)
6405 {
6406 	size_t sub_insn_idx, insn_idx;
6407 	struct bpf_program *subprog;
6408 	struct reloc_desc *relo;
6409 	struct bpf_insn *insn;
6410 	int err;
6411 
6412 	err = reloc_prog_func_and_line_info(obj, main_prog, prog);
6413 	if (err)
6414 		return err;
6415 
6416 	for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
6417 		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
6418 		if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn))
6419 			continue;
6420 
6421 		relo = find_prog_insn_relo(prog, insn_idx);
6422 		if (relo && relo->type == RELO_EXTERN_CALL)
6423 			/* kfunc relocations will be handled later
6424 			 * in bpf_object__relocate_data()
6425 			 */
6426 			continue;
6427 		if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) {
6428 			pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
6429 				prog->name, insn_idx, relo->type);
6430 			return -LIBBPF_ERRNO__RELOC;
6431 		}
6432 		if (relo) {
6433 			/* sub-program instruction index is a combination of
6434 			 * an offset of a symbol pointed to by relocation and
6435 			 * call instruction's imm field; for global functions,
6436 			 * call always has imm = -1, but for static functions
6437 			 * relocation is against STT_SECTION and insn->imm
6438 			 * points to a start of a static function
6439 			 *
6440 			 * for subprog addr relocation, the relo->sym_off + insn->imm is
6441 			 * the byte offset in the corresponding section.
6442 			 */
6443 			if (relo->type == RELO_CALL)
6444 				sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
6445 			else
6446 				sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ;
6447 		} else if (insn_is_pseudo_func(insn)) {
6448 			/*
6449 			 * RELO_SUBPROG_ADDR relo is always emitted even if both
6450 			 * functions are in the same section, so it shouldn't reach here.
6451 			 */
6452 			pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n",
6453 				prog->name, insn_idx);
6454 			return -LIBBPF_ERRNO__RELOC;
6455 		} else {
6456 			/* if subprogram call is to a static function within
6457 			 * the same ELF section, there won't be any relocation
6458 			 * emitted, but it also means there is no additional
6459 			 * offset necessary, insns->imm is relative to
6460 			 * instruction's original position within the section
6461 			 */
6462 			sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
6463 		}
6464 
6465 		/* we enforce that sub-programs should be in .text section */
6466 		subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
6467 		if (!subprog) {
6468 			pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
6469 				prog->name);
6470 			return -LIBBPF_ERRNO__RELOC;
6471 		}
6472 
6473 		/* if it's the first call instruction calling into this
6474 		 * subprogram (meaning this subprog hasn't been processed
6475 		 * yet) within the context of current main program:
6476 		 *   - append it at the end of main program's instructions blog;
6477 		 *   - process is recursively, while current program is put on hold;
6478 		 *   - if that subprogram calls some other not yet processes
6479 		 *   subprogram, same thing will happen recursively until
6480 		 *   there are no more unprocesses subprograms left to append
6481 		 *   and relocate.
6482 		 */
6483 		if (subprog->sub_insn_off == 0) {
6484 			err = bpf_object__append_subprog_code(obj, main_prog, subprog);
6485 			if (err)
6486 				return err;
6487 			err = bpf_object__reloc_code(obj, main_prog, subprog);
6488 			if (err)
6489 				return err;
6490 		}
6491 
6492 		/* main_prog->insns memory could have been re-allocated, so
6493 		 * calculate pointer again
6494 		 */
6495 		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
6496 		/* calculate correct instruction position within current main
6497 		 * prog; each main prog can have a different set of
6498 		 * subprograms appended (potentially in different order as
6499 		 * well), so position of any subprog can be different for
6500 		 * different main programs
6501 		 */
6502 		insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
6503 
6504 		pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
6505 			 prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
6506 	}
6507 
6508 	return 0;
6509 }
6510 
6511 /*
6512  * Relocate sub-program calls.
6513  *
6514  * Algorithm operates as follows. Each entry-point BPF program (referred to as
6515  * main prog) is processed separately. For each subprog (non-entry functions,
6516  * that can be called from either entry progs or other subprogs) gets their
6517  * sub_insn_off reset to zero. This serves as indicator that this subprogram
6518  * hasn't been yet appended and relocated within current main prog. Once its
6519  * relocated, sub_insn_off will point at the position within current main prog
6520  * where given subprog was appended. This will further be used to relocate all
6521  * the call instructions jumping into this subprog.
6522  *
6523  * We start with main program and process all call instructions. If the call
6524  * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
6525  * is zero), subprog instructions are appended at the end of main program's
6526  * instruction array. Then main program is "put on hold" while we recursively
6527  * process newly appended subprogram. If that subprogram calls into another
6528  * subprogram that hasn't been appended, new subprogram is appended again to
6529  * the *main* prog's instructions (subprog's instructions are always left
6530  * untouched, as they need to be in unmodified state for subsequent main progs
6531  * and subprog instructions are always sent only as part of a main prog) and
6532  * the process continues recursively. Once all the subprogs called from a main
6533  * prog or any of its subprogs are appended (and relocated), all their
6534  * positions within finalized instructions array are known, so it's easy to
6535  * rewrite call instructions with correct relative offsets, corresponding to
6536  * desired target subprog.
6537  *
6538  * Its important to realize that some subprogs might not be called from some
6539  * main prog and any of its called/used subprogs. Those will keep their
6540  * subprog->sub_insn_off as zero at all times and won't be appended to current
6541  * main prog and won't be relocated within the context of current main prog.
6542  * They might still be used from other main progs later.
6543  *
6544  * Visually this process can be shown as below. Suppose we have two main
6545  * programs mainA and mainB and BPF object contains three subprogs: subA,
6546  * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
6547  * subC both call subB:
6548  *
6549  *        +--------+ +-------+
6550  *        |        v v       |
6551  *     +--+---+ +--+-+-+ +---+--+
6552  *     | subA | | subB | | subC |
6553  *     +--+---+ +------+ +---+--+
6554  *        ^                  ^
6555  *        |                  |
6556  *    +---+-------+   +------+----+
6557  *    |   mainA   |   |   mainB   |
6558  *    +-----------+   +-----------+
6559  *
6560  * We'll start relocating mainA, will find subA, append it and start
6561  * processing sub A recursively:
6562  *
6563  *    +-----------+------+
6564  *    |   mainA   | subA |
6565  *    +-----------+------+
6566  *
6567  * At this point we notice that subB is used from subA, so we append it and
6568  * relocate (there are no further subcalls from subB):
6569  *
6570  *    +-----------+------+------+
6571  *    |   mainA   | subA | subB |
6572  *    +-----------+------+------+
6573  *
6574  * At this point, we relocate subA calls, then go one level up and finish with
6575  * relocatin mainA calls. mainA is done.
6576  *
6577  * For mainB process is similar but results in different order. We start with
6578  * mainB and skip subA and subB, as mainB never calls them (at least
6579  * directly), but we see subC is needed, so we append and start processing it:
6580  *
6581  *    +-----------+------+
6582  *    |   mainB   | subC |
6583  *    +-----------+------+
6584  * Now we see subC needs subB, so we go back to it, append and relocate it:
6585  *
6586  *    +-----------+------+------+
6587  *    |   mainB   | subC | subB |
6588  *    +-----------+------+------+
6589  *
6590  * At this point we unwind recursion, relocate calls in subC, then in mainB.
6591  */
6592 static int
bpf_object__relocate_calls(struct bpf_object * obj,struct bpf_program * prog)6593 bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
6594 {
6595 	struct bpf_program *subprog;
6596 	int i, err;
6597 
6598 	/* mark all subprogs as not relocated (yet) within the context of
6599 	 * current main program
6600 	 */
6601 	for (i = 0; i < obj->nr_programs; i++) {
6602 		subprog = &obj->programs[i];
6603 		if (!prog_is_subprog(obj, subprog))
6604 			continue;
6605 
6606 		subprog->sub_insn_off = 0;
6607 	}
6608 
6609 	err = bpf_object__reloc_code(obj, prog, prog);
6610 	if (err)
6611 		return err;
6612 
6613 	return 0;
6614 }
6615 
6616 static void
bpf_object__free_relocs(struct bpf_object * obj)6617 bpf_object__free_relocs(struct bpf_object *obj)
6618 {
6619 	struct bpf_program *prog;
6620 	int i;
6621 
6622 	/* free up relocation descriptors */
6623 	for (i = 0; i < obj->nr_programs; i++) {
6624 		prog = &obj->programs[i];
6625 		zfree(&prog->reloc_desc);
6626 		prog->nr_reloc = 0;
6627 	}
6628 }
6629 
cmp_relocs(const void * _a,const void * _b)6630 static int cmp_relocs(const void *_a, const void *_b)
6631 {
6632 	const struct reloc_desc *a = _a;
6633 	const struct reloc_desc *b = _b;
6634 
6635 	if (a->insn_idx != b->insn_idx)
6636 		return a->insn_idx < b->insn_idx ? -1 : 1;
6637 
6638 	/* no two relocations should have the same insn_idx, but ... */
6639 	if (a->type != b->type)
6640 		return a->type < b->type ? -1 : 1;
6641 
6642 	return 0;
6643 }
6644 
bpf_object__sort_relos(struct bpf_object * obj)6645 static void bpf_object__sort_relos(struct bpf_object *obj)
6646 {
6647 	int i;
6648 
6649 	for (i = 0; i < obj->nr_programs; i++) {
6650 		struct bpf_program *p = &obj->programs[i];
6651 
6652 		if (!p->nr_reloc)
6653 			continue;
6654 
6655 		qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
6656 	}
6657 }
6658 
bpf_prog_assign_exc_cb(struct bpf_object * obj,struct bpf_program * prog)6659 static int bpf_prog_assign_exc_cb(struct bpf_object *obj, struct bpf_program *prog)
6660 {
6661 	const char *str = "exception_callback:";
6662 	size_t pfx_len = strlen(str);
6663 	int i, j, n;
6664 
6665 	if (!obj->btf || !kernel_supports(obj, FEAT_BTF_DECL_TAG))
6666 		return 0;
6667 
6668 	n = btf__type_cnt(obj->btf);
6669 	for (i = 1; i < n; i++) {
6670 		const char *name;
6671 		struct btf_type *t;
6672 
6673 		t = btf_type_by_id(obj->btf, i);
6674 		if (!btf_is_decl_tag(t) || btf_decl_tag(t)->component_idx != -1)
6675 			continue;
6676 
6677 		name = btf__str_by_offset(obj->btf, t->name_off);
6678 		if (strncmp(name, str, pfx_len) != 0)
6679 			continue;
6680 
6681 		t = btf_type_by_id(obj->btf, t->type);
6682 		if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL) {
6683 			pr_warn("prog '%s': exception_callback:<value> decl tag not applied to the main program\n",
6684 				prog->name);
6685 			return -EINVAL;
6686 		}
6687 		if (strcmp(prog->name, btf__str_by_offset(obj->btf, t->name_off)) != 0)
6688 			continue;
6689 		/* Multiple callbacks are specified for the same prog,
6690 		 * the verifier will eventually return an error for this
6691 		 * case, hence simply skip appending a subprog.
6692 		 */
6693 		if (prog->exception_cb_idx >= 0) {
6694 			prog->exception_cb_idx = -1;
6695 			break;
6696 		}
6697 
6698 		name += pfx_len;
6699 		if (str_is_empty(name)) {
6700 			pr_warn("prog '%s': exception_callback:<value> decl tag contains empty value\n",
6701 				prog->name);
6702 			return -EINVAL;
6703 		}
6704 
6705 		for (j = 0; j < obj->nr_programs; j++) {
6706 			struct bpf_program *subprog = &obj->programs[j];
6707 
6708 			if (!prog_is_subprog(obj, subprog))
6709 				continue;
6710 			if (strcmp(name, subprog->name) != 0)
6711 				continue;
6712 			/* Enforce non-hidden, as from verifier point of
6713 			 * view it expects global functions, whereas the
6714 			 * mark_btf_static fixes up linkage as static.
6715 			 */
6716 			if (!subprog->sym_global || subprog->mark_btf_static) {
6717 				pr_warn("prog '%s': exception callback %s must be a global non-hidden function\n",
6718 					prog->name, subprog->name);
6719 				return -EINVAL;
6720 			}
6721 			/* Let's see if we already saw a static exception callback with the same name */
6722 			if (prog->exception_cb_idx >= 0) {
6723 				pr_warn("prog '%s': multiple subprogs with same name as exception callback '%s'\n",
6724 					prog->name, subprog->name);
6725 				return -EINVAL;
6726 			}
6727 			prog->exception_cb_idx = j;
6728 			break;
6729 		}
6730 
6731 		if (prog->exception_cb_idx >= 0)
6732 			continue;
6733 
6734 		pr_warn("prog '%s': cannot find exception callback '%s'\n", prog->name, name);
6735 		return -ENOENT;
6736 	}
6737 
6738 	return 0;
6739 }
6740 
6741 static struct {
6742 	enum bpf_prog_type prog_type;
6743 	const char *ctx_name;
6744 } global_ctx_map[] = {
6745 	{ BPF_PROG_TYPE_CGROUP_DEVICE,           "bpf_cgroup_dev_ctx" },
6746 	{ BPF_PROG_TYPE_CGROUP_SKB,              "__sk_buff" },
6747 	{ BPF_PROG_TYPE_CGROUP_SOCK,             "bpf_sock" },
6748 	{ BPF_PROG_TYPE_CGROUP_SOCK_ADDR,        "bpf_sock_addr" },
6749 	{ BPF_PROG_TYPE_CGROUP_SOCKOPT,          "bpf_sockopt" },
6750 	{ BPF_PROG_TYPE_CGROUP_SYSCTL,           "bpf_sysctl" },
6751 	{ BPF_PROG_TYPE_FLOW_DISSECTOR,          "__sk_buff" },
6752 	{ BPF_PROG_TYPE_KPROBE,                  "bpf_user_pt_regs_t" },
6753 	{ BPF_PROG_TYPE_LWT_IN,                  "__sk_buff" },
6754 	{ BPF_PROG_TYPE_LWT_OUT,                 "__sk_buff" },
6755 	{ BPF_PROG_TYPE_LWT_SEG6LOCAL,           "__sk_buff" },
6756 	{ BPF_PROG_TYPE_LWT_XMIT,                "__sk_buff" },
6757 	{ BPF_PROG_TYPE_NETFILTER,               "bpf_nf_ctx" },
6758 	{ BPF_PROG_TYPE_PERF_EVENT,              "bpf_perf_event_data" },
6759 	{ BPF_PROG_TYPE_RAW_TRACEPOINT,          "bpf_raw_tracepoint_args" },
6760 	{ BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, "bpf_raw_tracepoint_args" },
6761 	{ BPF_PROG_TYPE_SCHED_ACT,               "__sk_buff" },
6762 	{ BPF_PROG_TYPE_SCHED_CLS,               "__sk_buff" },
6763 	{ BPF_PROG_TYPE_SK_LOOKUP,               "bpf_sk_lookup" },
6764 	{ BPF_PROG_TYPE_SK_MSG,                  "sk_msg_md" },
6765 	{ BPF_PROG_TYPE_SK_REUSEPORT,            "sk_reuseport_md" },
6766 	{ BPF_PROG_TYPE_SK_SKB,                  "__sk_buff" },
6767 	{ BPF_PROG_TYPE_SOCK_OPS,                "bpf_sock_ops" },
6768 	{ BPF_PROG_TYPE_SOCKET_FILTER,           "__sk_buff" },
6769 	{ BPF_PROG_TYPE_XDP,                     "xdp_md" },
6770 	/* all other program types don't have "named" context structs */
6771 };
6772 
6773 /* forward declarations for arch-specific underlying types of bpf_user_pt_regs_t typedef,
6774  * for below __builtin_types_compatible_p() checks;
6775  * with this approach we don't need any extra arch-specific #ifdef guards
6776  */
6777 struct pt_regs;
6778 struct user_pt_regs;
6779 struct user_regs_struct;
6780 
need_func_arg_type_fixup(const struct btf * btf,const struct bpf_program * prog,const char * subprog_name,int arg_idx,int arg_type_id,const char * ctx_name)6781 static bool need_func_arg_type_fixup(const struct btf *btf, const struct bpf_program *prog,
6782 				     const char *subprog_name, int arg_idx,
6783 				     int arg_type_id, const char *ctx_name)
6784 {
6785 	const struct btf_type *t;
6786 	const char *tname;
6787 
6788 	/* check if existing parameter already matches verifier expectations */
6789 	t = skip_mods_and_typedefs(btf, arg_type_id, NULL);
6790 	if (!btf_is_ptr(t))
6791 		goto out_warn;
6792 
6793 	/* typedef bpf_user_pt_regs_t is a special PITA case, valid for kprobe
6794 	 * and perf_event programs, so check this case early on and forget
6795 	 * about it for subsequent checks
6796 	 */
6797 	while (btf_is_mod(t))
6798 		t = btf__type_by_id(btf, t->type);
6799 	if (btf_is_typedef(t) &&
6800 	    (prog->type == BPF_PROG_TYPE_KPROBE || prog->type == BPF_PROG_TYPE_PERF_EVENT)) {
6801 		tname = btf__str_by_offset(btf, t->name_off) ?: "<anon>";
6802 		if (strcmp(tname, "bpf_user_pt_regs_t") == 0)
6803 			return false; /* canonical type for kprobe/perf_event */
6804 	}
6805 
6806 	/* now we can ignore typedefs moving forward */
6807 	t = skip_mods_and_typedefs(btf, t->type, NULL);
6808 
6809 	/* if it's `void *`, definitely fix up BTF info */
6810 	if (btf_is_void(t))
6811 		return true;
6812 
6813 	/* if it's already proper canonical type, no need to fix up */
6814 	tname = btf__str_by_offset(btf, t->name_off) ?: "<anon>";
6815 	if (btf_is_struct(t) && strcmp(tname, ctx_name) == 0)
6816 		return false;
6817 
6818 	/* special cases */
6819 	switch (prog->type) {
6820 	case BPF_PROG_TYPE_KPROBE:
6821 		/* `struct pt_regs *` is expected, but we need to fix up */
6822 		if (btf_is_struct(t) && strcmp(tname, "pt_regs") == 0)
6823 			return true;
6824 		break;
6825 	case BPF_PROG_TYPE_PERF_EVENT:
6826 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) &&
6827 		    btf_is_struct(t) && strcmp(tname, "pt_regs") == 0)
6828 			return true;
6829 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) &&
6830 		    btf_is_struct(t) && strcmp(tname, "user_pt_regs") == 0)
6831 			return true;
6832 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) &&
6833 		    btf_is_struct(t) && strcmp(tname, "user_regs_struct") == 0)
6834 			return true;
6835 		break;
6836 	case BPF_PROG_TYPE_RAW_TRACEPOINT:
6837 	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
6838 		/* allow u64* as ctx */
6839 		if (btf_is_int(t) && t->size == 8)
6840 			return true;
6841 		break;
6842 	default:
6843 		break;
6844 	}
6845 
6846 out_warn:
6847 	pr_warn("prog '%s': subprog '%s' arg#%d is expected to be of `struct %s *` type\n",
6848 		prog->name, subprog_name, arg_idx, ctx_name);
6849 	return false;
6850 }
6851 
clone_func_btf_info(struct btf * btf,int orig_fn_id,struct bpf_program * prog)6852 static int clone_func_btf_info(struct btf *btf, int orig_fn_id, struct bpf_program *prog)
6853 {
6854 	int fn_id, fn_proto_id, ret_type_id, orig_proto_id;
6855 	int i, err, arg_cnt, fn_name_off, linkage;
6856 	struct btf_type *fn_t, *fn_proto_t, *t;
6857 	struct btf_param *p;
6858 
6859 	/* caller already validated FUNC -> FUNC_PROTO validity */
6860 	fn_t = btf_type_by_id(btf, orig_fn_id);
6861 	fn_proto_t = btf_type_by_id(btf, fn_t->type);
6862 
6863 	/* Note that each btf__add_xxx() operation invalidates
6864 	 * all btf_type and string pointers, so we need to be
6865 	 * very careful when cloning BTF types. BTF type
6866 	 * pointers have to be always refetched. And to avoid
6867 	 * problems with invalidated string pointers, we
6868 	 * add empty strings initially, then just fix up
6869 	 * name_off offsets in place. Offsets are stable for
6870 	 * existing strings, so that works out.
6871 	 */
6872 	fn_name_off = fn_t->name_off; /* we are about to invalidate fn_t */
6873 	linkage = btf_func_linkage(fn_t);
6874 	orig_proto_id = fn_t->type; /* original FUNC_PROTO ID */
6875 	ret_type_id = fn_proto_t->type; /* fn_proto_t will be invalidated */
6876 	arg_cnt = btf_vlen(fn_proto_t);
6877 
6878 	/* clone FUNC_PROTO and its params */
6879 	fn_proto_id = btf__add_func_proto(btf, ret_type_id);
6880 	if (fn_proto_id < 0)
6881 		return -EINVAL;
6882 
6883 	for (i = 0; i < arg_cnt; i++) {
6884 		int name_off;
6885 
6886 		/* copy original parameter data */
6887 		t = btf_type_by_id(btf, orig_proto_id);
6888 		p = &btf_params(t)[i];
6889 		name_off = p->name_off;
6890 
6891 		err = btf__add_func_param(btf, "", p->type);
6892 		if (err)
6893 			return err;
6894 
6895 		fn_proto_t = btf_type_by_id(btf, fn_proto_id);
6896 		p = &btf_params(fn_proto_t)[i];
6897 		p->name_off = name_off; /* use remembered str offset */
6898 	}
6899 
6900 	/* clone FUNC now, btf__add_func() enforces non-empty name, so use
6901 	 * entry program's name as a placeholder, which we replace immediately
6902 	 * with original name_off
6903 	 */
6904 	fn_id = btf__add_func(btf, prog->name, linkage, fn_proto_id);
6905 	if (fn_id < 0)
6906 		return -EINVAL;
6907 
6908 	fn_t = btf_type_by_id(btf, fn_id);
6909 	fn_t->name_off = fn_name_off; /* reuse original string */
6910 
6911 	return fn_id;
6912 }
6913 
6914 /* Check if main program or global subprog's function prototype has `arg:ctx`
6915  * argument tags, and, if necessary, substitute correct type to match what BPF
6916  * verifier would expect, taking into account specific program type. This
6917  * allows to support __arg_ctx tag transparently on old kernels that don't yet
6918  * have a native support for it in the verifier, making user's life much
6919  * easier.
6920  */
bpf_program_fixup_func_info(struct bpf_object * obj,struct bpf_program * prog)6921 static int bpf_program_fixup_func_info(struct bpf_object *obj, struct bpf_program *prog)
6922 {
6923 	const char *ctx_name = NULL, *ctx_tag = "arg:ctx", *fn_name;
6924 	struct bpf_func_info_min *func_rec;
6925 	struct btf_type *fn_t, *fn_proto_t;
6926 	struct btf *btf = obj->btf;
6927 	const struct btf_type *t;
6928 	struct btf_param *p;
6929 	int ptr_id = 0, struct_id, tag_id, orig_fn_id;
6930 	int i, n, arg_idx, arg_cnt, err, rec_idx;
6931 	int *orig_ids;
6932 
6933 	/* no .BTF.ext, no problem */
6934 	if (!obj->btf_ext || !prog->func_info)
6935 		return 0;
6936 
6937 	/* don't do any fix ups if kernel natively supports __arg_ctx */
6938 	if (kernel_supports(obj, FEAT_ARG_CTX_TAG))
6939 		return 0;
6940 
6941 	/* some BPF program types just don't have named context structs, so
6942 	 * this fallback mechanism doesn't work for them
6943 	 */
6944 	for (i = 0; i < ARRAY_SIZE(global_ctx_map); i++) {
6945 		if (global_ctx_map[i].prog_type != prog->type)
6946 			continue;
6947 		ctx_name = global_ctx_map[i].ctx_name;
6948 		break;
6949 	}
6950 	if (!ctx_name)
6951 		return 0;
6952 
6953 	/* remember original func BTF IDs to detect if we already cloned them */
6954 	orig_ids = calloc(prog->func_info_cnt, sizeof(*orig_ids));
6955 	if (!orig_ids)
6956 		return -ENOMEM;
6957 	for (i = 0; i < prog->func_info_cnt; i++) {
6958 		func_rec = prog->func_info + prog->func_info_rec_size * i;
6959 		orig_ids[i] = func_rec->type_id;
6960 	}
6961 
6962 	/* go through each DECL_TAG with "arg:ctx" and see if it points to one
6963 	 * of our subprogs; if yes and subprog is global and needs adjustment,
6964 	 * clone and adjust FUNC -> FUNC_PROTO combo
6965 	 */
6966 	for (i = 1, n = btf__type_cnt(btf); i < n; i++) {
6967 		/* only DECL_TAG with "arg:ctx" value are interesting */
6968 		t = btf__type_by_id(btf, i);
6969 		if (!btf_is_decl_tag(t))
6970 			continue;
6971 		if (strcmp(btf__str_by_offset(btf, t->name_off), ctx_tag) != 0)
6972 			continue;
6973 
6974 		/* only global funcs need adjustment, if at all */
6975 		orig_fn_id = t->type;
6976 		fn_t = btf_type_by_id(btf, orig_fn_id);
6977 		if (!btf_is_func(fn_t) || btf_func_linkage(fn_t) != BTF_FUNC_GLOBAL)
6978 			continue;
6979 
6980 		/* sanity check FUNC -> FUNC_PROTO chain, just in case */
6981 		fn_proto_t = btf_type_by_id(btf, fn_t->type);
6982 		if (!fn_proto_t || !btf_is_func_proto(fn_proto_t))
6983 			continue;
6984 
6985 		/* find corresponding func_info record */
6986 		func_rec = NULL;
6987 		for (rec_idx = 0; rec_idx < prog->func_info_cnt; rec_idx++) {
6988 			if (orig_ids[rec_idx] == t->type) {
6989 				func_rec = prog->func_info + prog->func_info_rec_size * rec_idx;
6990 				break;
6991 			}
6992 		}
6993 		/* current main program doesn't call into this subprog */
6994 		if (!func_rec)
6995 			continue;
6996 
6997 		/* some more sanity checking of DECL_TAG */
6998 		arg_cnt = btf_vlen(fn_proto_t);
6999 		arg_idx = btf_decl_tag(t)->component_idx;
7000 		if (arg_idx < 0 || arg_idx >= arg_cnt)
7001 			continue;
7002 
7003 		/* check if we should fix up argument type */
7004 		p = &btf_params(fn_proto_t)[arg_idx];
7005 		fn_name = btf__str_by_offset(btf, fn_t->name_off) ?: "<anon>";
7006 		if (!need_func_arg_type_fixup(btf, prog, fn_name, arg_idx, p->type, ctx_name))
7007 			continue;
7008 
7009 		/* clone fn/fn_proto, unless we already did it for another arg */
7010 		if (func_rec->type_id == orig_fn_id) {
7011 			int fn_id;
7012 
7013 			fn_id = clone_func_btf_info(btf, orig_fn_id, prog);
7014 			if (fn_id < 0) {
7015 				err = fn_id;
7016 				goto err_out;
7017 			}
7018 
7019 			/* point func_info record to a cloned FUNC type */
7020 			func_rec->type_id = fn_id;
7021 		}
7022 
7023 		/* create PTR -> STRUCT type chain to mark PTR_TO_CTX argument;
7024 		 * we do it just once per main BPF program, as all global
7025 		 * funcs share the same program type, so need only PTR ->
7026 		 * STRUCT type chain
7027 		 */
7028 		if (ptr_id == 0) {
7029 			struct_id = btf__add_struct(btf, ctx_name, 0);
7030 			ptr_id = btf__add_ptr(btf, struct_id);
7031 			if (ptr_id < 0 || struct_id < 0) {
7032 				err = -EINVAL;
7033 				goto err_out;
7034 			}
7035 		}
7036 
7037 		/* for completeness, clone DECL_TAG and point it to cloned param */
7038 		tag_id = btf__add_decl_tag(btf, ctx_tag, func_rec->type_id, arg_idx);
7039 		if (tag_id < 0) {
7040 			err = -EINVAL;
7041 			goto err_out;
7042 		}
7043 
7044 		/* all the BTF manipulations invalidated pointers, refetch them */
7045 		fn_t = btf_type_by_id(btf, func_rec->type_id);
7046 		fn_proto_t = btf_type_by_id(btf, fn_t->type);
7047 
7048 		/* fix up type ID pointed to by param */
7049 		p = &btf_params(fn_proto_t)[arg_idx];
7050 		p->type = ptr_id;
7051 	}
7052 
7053 	free(orig_ids);
7054 	return 0;
7055 err_out:
7056 	free(orig_ids);
7057 	return err;
7058 }
7059 
bpf_object__relocate(struct bpf_object * obj,const char * targ_btf_path)7060 static int bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
7061 {
7062 	struct bpf_program *prog;
7063 	size_t i, j;
7064 	int err;
7065 
7066 	if (obj->btf_ext) {
7067 		err = bpf_object__relocate_core(obj, targ_btf_path);
7068 		if (err) {
7069 			pr_warn("failed to perform CO-RE relocations: %s\n",
7070 				errstr(err));
7071 			return err;
7072 		}
7073 		bpf_object__sort_relos(obj);
7074 	}
7075 
7076 	/* Before relocating calls pre-process relocations and mark
7077 	 * few ld_imm64 instructions that points to subprogs.
7078 	 * Otherwise bpf_object__reloc_code() later would have to consider
7079 	 * all ld_imm64 insns as relocation candidates. That would
7080 	 * reduce relocation speed, since amount of find_prog_insn_relo()
7081 	 * would increase and most of them will fail to find a relo.
7082 	 */
7083 	for (i = 0; i < obj->nr_programs; i++) {
7084 		prog = &obj->programs[i];
7085 		for (j = 0; j < prog->nr_reloc; j++) {
7086 			struct reloc_desc *relo = &prog->reloc_desc[j];
7087 			struct bpf_insn *insn = &prog->insns[relo->insn_idx];
7088 
7089 			/* mark the insn, so it's recognized by insn_is_pseudo_func() */
7090 			if (relo->type == RELO_SUBPROG_ADDR)
7091 				insn[0].src_reg = BPF_PSEUDO_FUNC;
7092 		}
7093 	}
7094 
7095 	/* relocate subprogram calls and append used subprograms to main
7096 	 * programs; each copy of subprogram code needs to be relocated
7097 	 * differently for each main program, because its code location might
7098 	 * have changed.
7099 	 * Append subprog relos to main programs to allow data relos to be
7100 	 * processed after text is completely relocated.
7101 	 */
7102 	for (i = 0; i < obj->nr_programs; i++) {
7103 		prog = &obj->programs[i];
7104 		/* sub-program's sub-calls are relocated within the context of
7105 		 * its main program only
7106 		 */
7107 		if (prog_is_subprog(obj, prog))
7108 			continue;
7109 		if (!prog->autoload)
7110 			continue;
7111 
7112 		err = bpf_object__relocate_calls(obj, prog);
7113 		if (err) {
7114 			pr_warn("prog '%s': failed to relocate calls: %s\n",
7115 				prog->name, errstr(err));
7116 			return err;
7117 		}
7118 
7119 		err = bpf_prog_assign_exc_cb(obj, prog);
7120 		if (err)
7121 			return err;
7122 		/* Now, also append exception callback if it has not been done already. */
7123 		if (prog->exception_cb_idx >= 0) {
7124 			struct bpf_program *subprog = &obj->programs[prog->exception_cb_idx];
7125 
7126 			/* Calling exception callback directly is disallowed, which the
7127 			 * verifier will reject later. In case it was processed already,
7128 			 * we can skip this step, otherwise for all other valid cases we
7129 			 * have to append exception callback now.
7130 			 */
7131 			if (subprog->sub_insn_off == 0) {
7132 				err = bpf_object__append_subprog_code(obj, prog, subprog);
7133 				if (err)
7134 					return err;
7135 				err = bpf_object__reloc_code(obj, prog, subprog);
7136 				if (err)
7137 					return err;
7138 			}
7139 		}
7140 	}
7141 	for (i = 0; i < obj->nr_programs; i++) {
7142 		prog = &obj->programs[i];
7143 		if (prog_is_subprog(obj, prog))
7144 			continue;
7145 		if (!prog->autoload)
7146 			continue;
7147 
7148 		/* Process data relos for main programs */
7149 		err = bpf_object__relocate_data(obj, prog);
7150 		if (err) {
7151 			pr_warn("prog '%s': failed to relocate data references: %s\n",
7152 				prog->name, errstr(err));
7153 			return err;
7154 		}
7155 
7156 		/* Fix up .BTF.ext information, if necessary */
7157 		err = bpf_program_fixup_func_info(obj, prog);
7158 		if (err) {
7159 			pr_warn("prog '%s': failed to perform .BTF.ext fix ups: %s\n",
7160 				prog->name, errstr(err));
7161 			return err;
7162 		}
7163 	}
7164 
7165 	return 0;
7166 }
7167 
7168 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
7169 					    Elf64_Shdr *shdr, Elf_Data *data);
7170 
bpf_object__collect_map_relos(struct bpf_object * obj,Elf64_Shdr * shdr,Elf_Data * data)7171 static int bpf_object__collect_map_relos(struct bpf_object *obj,
7172 					 Elf64_Shdr *shdr, Elf_Data *data)
7173 {
7174 	const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
7175 	int i, j, nrels, new_sz;
7176 	const struct btf_var_secinfo *vi = NULL;
7177 	const struct btf_type *sec, *var, *def;
7178 	struct bpf_map *map = NULL, *targ_map = NULL;
7179 	struct bpf_program *targ_prog = NULL;
7180 	bool is_prog_array, is_map_in_map;
7181 	const struct btf_member *member;
7182 	const char *name, *mname, *type;
7183 	unsigned int moff;
7184 	Elf64_Sym *sym;
7185 	Elf64_Rel *rel;
7186 	void *tmp;
7187 
7188 	if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
7189 		return -EINVAL;
7190 	sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id);
7191 	if (!sec)
7192 		return -EINVAL;
7193 
7194 	nrels = shdr->sh_size / shdr->sh_entsize;
7195 	for (i = 0; i < nrels; i++) {
7196 		rel = elf_rel_by_idx(data, i);
7197 		if (!rel) {
7198 			pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
7199 			return -LIBBPF_ERRNO__FORMAT;
7200 		}
7201 
7202 		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
7203 		if (!sym) {
7204 			pr_warn(".maps relo #%d: symbol %zx not found\n",
7205 				i, (size_t)ELF64_R_SYM(rel->r_info));
7206 			return -LIBBPF_ERRNO__FORMAT;
7207 		}
7208 		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
7209 
7210 		pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n",
7211 			 i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value,
7212 			 (size_t)rel->r_offset, sym->st_name, name);
7213 
7214 		for (j = 0; j < obj->nr_maps; j++) {
7215 			map = &obj->maps[j];
7216 			if (map->sec_idx != obj->efile.btf_maps_shndx)
7217 				continue;
7218 
7219 			vi = btf_var_secinfos(sec) + map->btf_var_idx;
7220 			if (vi->offset <= rel->r_offset &&
7221 			    rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size)
7222 				break;
7223 		}
7224 		if (j == obj->nr_maps) {
7225 			pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n",
7226 				i, name, (size_t)rel->r_offset);
7227 			return -EINVAL;
7228 		}
7229 
7230 		is_map_in_map = bpf_map_type__is_map_in_map(map->def.type);
7231 		is_prog_array = map->def.type == BPF_MAP_TYPE_PROG_ARRAY;
7232 		type = is_map_in_map ? "map" : "prog";
7233 		if (is_map_in_map) {
7234 			if (sym->st_shndx != obj->efile.btf_maps_shndx) {
7235 				pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
7236 					i, name);
7237 				return -LIBBPF_ERRNO__RELOC;
7238 			}
7239 			if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS &&
7240 			    map->def.key_size != sizeof(int)) {
7241 				pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n",
7242 					i, map->name, sizeof(int));
7243 				return -EINVAL;
7244 			}
7245 			targ_map = bpf_object__find_map_by_name(obj, name);
7246 			if (!targ_map) {
7247 				pr_warn(".maps relo #%d: '%s' isn't a valid map reference\n",
7248 					i, name);
7249 				return -ESRCH;
7250 			}
7251 		} else if (is_prog_array) {
7252 			targ_prog = bpf_object__find_program_by_name(obj, name);
7253 			if (!targ_prog) {
7254 				pr_warn(".maps relo #%d: '%s' isn't a valid program reference\n",
7255 					i, name);
7256 				return -ESRCH;
7257 			}
7258 			if (targ_prog->sec_idx != sym->st_shndx ||
7259 			    targ_prog->sec_insn_off * 8 != sym->st_value ||
7260 			    prog_is_subprog(obj, targ_prog)) {
7261 				pr_warn(".maps relo #%d: '%s' isn't an entry-point program\n",
7262 					i, name);
7263 				return -LIBBPF_ERRNO__RELOC;
7264 			}
7265 		} else {
7266 			return -EINVAL;
7267 		}
7268 
7269 		var = btf__type_by_id(obj->btf, vi->type);
7270 		def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
7271 		if (btf_vlen(def) == 0)
7272 			return -EINVAL;
7273 		member = btf_members(def) + btf_vlen(def) - 1;
7274 		mname = btf__name_by_offset(obj->btf, member->name_off);
7275 		if (strcmp(mname, "values"))
7276 			return -EINVAL;
7277 
7278 		moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
7279 		if (rel->r_offset - vi->offset < moff)
7280 			return -EINVAL;
7281 
7282 		moff = rel->r_offset - vi->offset - moff;
7283 		/* here we use BPF pointer size, which is always 64 bit, as we
7284 		 * are parsing ELF that was built for BPF target
7285 		 */
7286 		if (moff % bpf_ptr_sz)
7287 			return -EINVAL;
7288 		moff /= bpf_ptr_sz;
7289 		if (moff >= map->init_slots_sz) {
7290 			new_sz = moff + 1;
7291 			tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
7292 			if (!tmp)
7293 				return -ENOMEM;
7294 			map->init_slots = tmp;
7295 			memset(map->init_slots + map->init_slots_sz, 0,
7296 			       (new_sz - map->init_slots_sz) * host_ptr_sz);
7297 			map->init_slots_sz = new_sz;
7298 		}
7299 		map->init_slots[moff] = is_map_in_map ? (void *)targ_map : (void *)targ_prog;
7300 
7301 		pr_debug(".maps relo #%d: map '%s' slot [%d] points to %s '%s'\n",
7302 			 i, map->name, moff, type, name);
7303 	}
7304 
7305 	return 0;
7306 }
7307 
bpf_object__collect_relos(struct bpf_object * obj)7308 static int bpf_object__collect_relos(struct bpf_object *obj)
7309 {
7310 	int i, err;
7311 
7312 	for (i = 0; i < obj->efile.sec_cnt; i++) {
7313 		struct elf_sec_desc *sec_desc = &obj->efile.secs[i];
7314 		Elf64_Shdr *shdr;
7315 		Elf_Data *data;
7316 		int idx;
7317 
7318 		if (sec_desc->sec_type != SEC_RELO)
7319 			continue;
7320 
7321 		shdr = sec_desc->shdr;
7322 		data = sec_desc->data;
7323 		idx = shdr->sh_info;
7324 
7325 		if (shdr->sh_type != SHT_REL || idx < 0 || idx >= obj->efile.sec_cnt) {
7326 			pr_warn("internal error at %d\n", __LINE__);
7327 			return -LIBBPF_ERRNO__INTERNAL;
7328 		}
7329 
7330 		if (obj->efile.secs[idx].sec_type == SEC_ST_OPS)
7331 			err = bpf_object__collect_st_ops_relos(obj, shdr, data);
7332 		else if (idx == obj->efile.btf_maps_shndx)
7333 			err = bpf_object__collect_map_relos(obj, shdr, data);
7334 		else
7335 			err = bpf_object__collect_prog_relos(obj, shdr, data);
7336 		if (err)
7337 			return err;
7338 	}
7339 
7340 	bpf_object__sort_relos(obj);
7341 	return 0;
7342 }
7343 
insn_is_helper_call(struct bpf_insn * insn,enum bpf_func_id * func_id)7344 static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
7345 {
7346 	if (BPF_CLASS(insn->code) == BPF_JMP &&
7347 	    BPF_OP(insn->code) == BPF_CALL &&
7348 	    BPF_SRC(insn->code) == BPF_K &&
7349 	    insn->src_reg == 0 &&
7350 	    insn->dst_reg == 0) {
7351 		    *func_id = insn->imm;
7352 		    return true;
7353 	}
7354 	return false;
7355 }
7356 
bpf_object__sanitize_prog(struct bpf_object * obj,struct bpf_program * prog)7357 static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
7358 {
7359 	struct bpf_insn *insn = prog->insns;
7360 	enum bpf_func_id func_id;
7361 	int i;
7362 
7363 	if (obj->gen_loader)
7364 		return 0;
7365 
7366 	for (i = 0; i < prog->insns_cnt; i++, insn++) {
7367 		if (!insn_is_helper_call(insn, &func_id))
7368 			continue;
7369 
7370 		/* on kernels that don't yet support
7371 		 * bpf_probe_read_{kernel,user}[_str] helpers, fall back
7372 		 * to bpf_probe_read() which works well for old kernels
7373 		 */
7374 		switch (func_id) {
7375 		case BPF_FUNC_probe_read_kernel:
7376 		case BPF_FUNC_probe_read_user:
7377 			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
7378 				insn->imm = BPF_FUNC_probe_read;
7379 			break;
7380 		case BPF_FUNC_probe_read_kernel_str:
7381 		case BPF_FUNC_probe_read_user_str:
7382 			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
7383 				insn->imm = BPF_FUNC_probe_read_str;
7384 			break;
7385 		default:
7386 			break;
7387 		}
7388 	}
7389 	return 0;
7390 }
7391 
7392 static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
7393 				     int *btf_obj_fd, int *btf_type_id);
7394 
7395 /* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported sec_defs */
libbpf_prepare_prog_load(struct bpf_program * prog,struct bpf_prog_load_opts * opts,long cookie)7396 static int libbpf_prepare_prog_load(struct bpf_program *prog,
7397 				    struct bpf_prog_load_opts *opts, long cookie)
7398 {
7399 	enum sec_def_flags def = cookie;
7400 
7401 	/* old kernels might not support specifying expected_attach_type */
7402 	if ((def & SEC_EXP_ATTACH_OPT) && !kernel_supports(prog->obj, FEAT_EXP_ATTACH_TYPE))
7403 		opts->expected_attach_type = 0;
7404 
7405 	if (def & SEC_SLEEPABLE)
7406 		opts->prog_flags |= BPF_F_SLEEPABLE;
7407 
7408 	if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS))
7409 		opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
7410 
7411 	/* special check for usdt to use uprobe_multi link */
7412 	if ((def & SEC_USDT) && kernel_supports(prog->obj, FEAT_UPROBE_MULTI_LINK)) {
7413 		/* for BPF_TRACE_UPROBE_MULTI, user might want to query expected_attach_type
7414 		 * in prog, and expected_attach_type we set in kernel is from opts, so we
7415 		 * update both.
7416 		 */
7417 		prog->expected_attach_type = BPF_TRACE_UPROBE_MULTI;
7418 		opts->expected_attach_type = BPF_TRACE_UPROBE_MULTI;
7419 	}
7420 
7421 	if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
7422 		int btf_obj_fd = 0, btf_type_id = 0, err;
7423 		const char *attach_name;
7424 
7425 		attach_name = strchr(prog->sec_name, '/');
7426 		if (!attach_name) {
7427 			/* if BPF program is annotated with just SEC("fentry")
7428 			 * (or similar) without declaratively specifying
7429 			 * target, then it is expected that target will be
7430 			 * specified with bpf_program__set_attach_target() at
7431 			 * runtime before BPF object load step. If not, then
7432 			 * there is nothing to load into the kernel as BPF
7433 			 * verifier won't be able to validate BPF program
7434 			 * correctness anyways.
7435 			 */
7436 			pr_warn("prog '%s': no BTF-based attach target is specified, use bpf_program__set_attach_target()\n",
7437 				prog->name);
7438 			return -EINVAL;
7439 		}
7440 		attach_name++; /* skip over / */
7441 
7442 		err = libbpf_find_attach_btf_id(prog, attach_name, &btf_obj_fd, &btf_type_id);
7443 		if (err)
7444 			return err;
7445 
7446 		/* cache resolved BTF FD and BTF type ID in the prog */
7447 		prog->attach_btf_obj_fd = btf_obj_fd;
7448 		prog->attach_btf_id = btf_type_id;
7449 
7450 		/* but by now libbpf common logic is not utilizing
7451 		 * prog->atach_btf_obj_fd/prog->attach_btf_id anymore because
7452 		 * this callback is called after opts were populated by
7453 		 * libbpf, so this callback has to update opts explicitly here
7454 		 */
7455 		opts->attach_btf_obj_fd = btf_obj_fd;
7456 		opts->attach_btf_id = btf_type_id;
7457 	}
7458 	return 0;
7459 }
7460 
7461 static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz);
7462 
bpf_object_load_prog(struct bpf_object * obj,struct bpf_program * prog,struct bpf_insn * insns,int insns_cnt,const char * license,__u32 kern_version,int * prog_fd)7463 static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog,
7464 				struct bpf_insn *insns, int insns_cnt,
7465 				const char *license, __u32 kern_version, int *prog_fd)
7466 {
7467 	LIBBPF_OPTS(bpf_prog_load_opts, load_attr);
7468 	const char *prog_name = NULL;
7469 	size_t log_buf_size = 0;
7470 	char *log_buf = NULL, *tmp;
7471 	bool own_log_buf = true;
7472 	__u32 log_level = prog->log_level;
7473 	int ret, err;
7474 
7475 	/* Be more helpful by rejecting programs that can't be validated early
7476 	 * with more meaningful and actionable error message.
7477 	 */
7478 	switch (prog->type) {
7479 	case BPF_PROG_TYPE_UNSPEC:
7480 		/*
7481 		 * The program type must be set.  Most likely we couldn't find a proper
7482 		 * section definition at load time, and thus we didn't infer the type.
7483 		 */
7484 		pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
7485 			prog->name, prog->sec_name);
7486 		return -EINVAL;
7487 	case BPF_PROG_TYPE_STRUCT_OPS:
7488 		if (prog->attach_btf_id == 0) {
7489 			pr_warn("prog '%s': SEC(\"struct_ops\") program isn't referenced anywhere, did you forget to use it?\n",
7490 				prog->name);
7491 			return -EINVAL;
7492 		}
7493 		break;
7494 	default:
7495 		break;
7496 	}
7497 
7498 	if (!insns || !insns_cnt)
7499 		return -EINVAL;
7500 
7501 	if (kernel_supports(obj, FEAT_PROG_NAME))
7502 		prog_name = prog->name;
7503 	load_attr.attach_prog_fd = prog->attach_prog_fd;
7504 	load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
7505 	load_attr.attach_btf_id = prog->attach_btf_id;
7506 	load_attr.kern_version = kern_version;
7507 	load_attr.prog_ifindex = prog->prog_ifindex;
7508 	load_attr.expected_attach_type = prog->expected_attach_type;
7509 
7510 	/* specify func_info/line_info only if kernel supports them */
7511 	if (obj->btf && btf__fd(obj->btf) >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
7512 		load_attr.prog_btf_fd = btf__fd(obj->btf);
7513 		load_attr.func_info = prog->func_info;
7514 		load_attr.func_info_rec_size = prog->func_info_rec_size;
7515 		load_attr.func_info_cnt = prog->func_info_cnt;
7516 		load_attr.line_info = prog->line_info;
7517 		load_attr.line_info_rec_size = prog->line_info_rec_size;
7518 		load_attr.line_info_cnt = prog->line_info_cnt;
7519 	}
7520 	load_attr.log_level = log_level;
7521 	load_attr.prog_flags = prog->prog_flags;
7522 	load_attr.fd_array = obj->fd_array;
7523 
7524 	load_attr.token_fd = obj->token_fd;
7525 	if (obj->token_fd)
7526 		load_attr.prog_flags |= BPF_F_TOKEN_FD;
7527 
7528 	/* adjust load_attr if sec_def provides custom preload callback */
7529 	if (prog->sec_def && prog->sec_def->prog_prepare_load_fn) {
7530 		err = prog->sec_def->prog_prepare_load_fn(prog, &load_attr, prog->sec_def->cookie);
7531 		if (err < 0) {
7532 			pr_warn("prog '%s': failed to prepare load attributes: %s\n",
7533 				prog->name, errstr(err));
7534 			return err;
7535 		}
7536 		insns = prog->insns;
7537 		insns_cnt = prog->insns_cnt;
7538 	}
7539 
7540 	if (obj->gen_loader) {
7541 		bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name,
7542 				   license, insns, insns_cnt, &load_attr,
7543 				   prog - obj->programs);
7544 		*prog_fd = -1;
7545 		return 0;
7546 	}
7547 
7548 retry_load:
7549 	/* if log_level is zero, we don't request logs initially even if
7550 	 * custom log_buf is specified; if the program load fails, then we'll
7551 	 * bump log_level to 1 and use either custom log_buf or we'll allocate
7552 	 * our own and retry the load to get details on what failed
7553 	 */
7554 	if (log_level) {
7555 		if (prog->log_buf) {
7556 			log_buf = prog->log_buf;
7557 			log_buf_size = prog->log_size;
7558 			own_log_buf = false;
7559 		} else if (obj->log_buf) {
7560 			log_buf = obj->log_buf;
7561 			log_buf_size = obj->log_size;
7562 			own_log_buf = false;
7563 		} else {
7564 			log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size * 2);
7565 			tmp = realloc(log_buf, log_buf_size);
7566 			if (!tmp) {
7567 				ret = -ENOMEM;
7568 				goto out;
7569 			}
7570 			log_buf = tmp;
7571 			log_buf[0] = '\0';
7572 			own_log_buf = true;
7573 		}
7574 	}
7575 
7576 	load_attr.log_buf = log_buf;
7577 	load_attr.log_size = log_buf_size;
7578 	load_attr.log_level = log_level;
7579 
7580 	ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
7581 	if (ret >= 0) {
7582 		if (log_level && own_log_buf) {
7583 			pr_debug("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
7584 				 prog->name, log_buf);
7585 		}
7586 
7587 		if (obj->has_rodata && kernel_supports(obj, FEAT_PROG_BIND_MAP)) {
7588 			struct bpf_map *map;
7589 			int i;
7590 
7591 			for (i = 0; i < obj->nr_maps; i++) {
7592 				map = &prog->obj->maps[i];
7593 				if (map->libbpf_type != LIBBPF_MAP_RODATA)
7594 					continue;
7595 
7596 				if (bpf_prog_bind_map(ret, map->fd, NULL)) {
7597 					pr_warn("prog '%s': failed to bind map '%s': %s\n",
7598 						prog->name, map->real_name, errstr(errno));
7599 					/* Don't fail hard if can't bind rodata. */
7600 				}
7601 			}
7602 		}
7603 
7604 		*prog_fd = ret;
7605 		ret = 0;
7606 		goto out;
7607 	}
7608 
7609 	if (log_level == 0) {
7610 		log_level = 1;
7611 		goto retry_load;
7612 	}
7613 	/* On ENOSPC, increase log buffer size and retry, unless custom
7614 	 * log_buf is specified.
7615 	 * Be careful to not overflow u32, though. Kernel's log buf size limit
7616 	 * isn't part of UAPI so it can always be bumped to full 4GB. So don't
7617 	 * multiply by 2 unless we are sure we'll fit within 32 bits.
7618 	 * Currently, we'll get -EINVAL when we reach (UINT_MAX >> 2).
7619 	 */
7620 	if (own_log_buf && errno == ENOSPC && log_buf_size <= UINT_MAX / 2)
7621 		goto retry_load;
7622 
7623 	ret = -errno;
7624 
7625 	/* post-process verifier log to improve error descriptions */
7626 	fixup_verifier_log(prog, log_buf, log_buf_size);
7627 
7628 	pr_warn("prog '%s': BPF program load failed: %s\n", prog->name, errstr(errno));
7629 	pr_perm_msg(ret);
7630 
7631 	if (own_log_buf && log_buf && log_buf[0] != '\0') {
7632 		pr_warn("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
7633 			prog->name, log_buf);
7634 	}
7635 
7636 out:
7637 	if (own_log_buf)
7638 		free(log_buf);
7639 	return ret;
7640 }
7641 
find_prev_line(char * buf,char * cur)7642 static char *find_prev_line(char *buf, char *cur)
7643 {
7644 	char *p;
7645 
7646 	if (cur == buf) /* end of a log buf */
7647 		return NULL;
7648 
7649 	p = cur - 1;
7650 	while (p - 1 >= buf && *(p - 1) != '\n')
7651 		p--;
7652 
7653 	return p;
7654 }
7655 
patch_log(char * buf,size_t buf_sz,size_t log_sz,char * orig,size_t orig_sz,const char * patch)7656 static void patch_log(char *buf, size_t buf_sz, size_t log_sz,
7657 		      char *orig, size_t orig_sz, const char *patch)
7658 {
7659 	/* size of the remaining log content to the right from the to-be-replaced part */
7660 	size_t rem_sz = (buf + log_sz) - (orig + orig_sz);
7661 	size_t patch_sz = strlen(patch);
7662 
7663 	if (patch_sz != orig_sz) {
7664 		/* If patch line(s) are longer than original piece of verifier log,
7665 		 * shift log contents by (patch_sz - orig_sz) bytes to the right
7666 		 * starting from after to-be-replaced part of the log.
7667 		 *
7668 		 * If patch line(s) are shorter than original piece of verifier log,
7669 		 * shift log contents by (orig_sz - patch_sz) bytes to the left
7670 		 * starting from after to-be-replaced part of the log
7671 		 *
7672 		 * We need to be careful about not overflowing available
7673 		 * buf_sz capacity. If that's the case, we'll truncate the end
7674 		 * of the original log, as necessary.
7675 		 */
7676 		if (patch_sz > orig_sz) {
7677 			if (orig + patch_sz >= buf + buf_sz) {
7678 				/* patch is big enough to cover remaining space completely */
7679 				patch_sz -= (orig + patch_sz) - (buf + buf_sz) + 1;
7680 				rem_sz = 0;
7681 			} else if (patch_sz - orig_sz > buf_sz - log_sz) {
7682 				/* patch causes part of remaining log to be truncated */
7683 				rem_sz -= (patch_sz - orig_sz) - (buf_sz - log_sz);
7684 			}
7685 		}
7686 		/* shift remaining log to the right by calculated amount */
7687 		memmove(orig + patch_sz, orig + orig_sz, rem_sz);
7688 	}
7689 
7690 	memcpy(orig, patch, patch_sz);
7691 }
7692 
fixup_log_failed_core_relo(struct bpf_program * prog,char * buf,size_t buf_sz,size_t log_sz,char * line1,char * line2,char * line3)7693 static void fixup_log_failed_core_relo(struct bpf_program *prog,
7694 				       char *buf, size_t buf_sz, size_t log_sz,
7695 				       char *line1, char *line2, char *line3)
7696 {
7697 	/* Expected log for failed and not properly guarded CO-RE relocation:
7698 	 * line1 -> 123: (85) call unknown#195896080
7699 	 * line2 -> invalid func unknown#195896080
7700 	 * line3 -> <anything else or end of buffer>
7701 	 *
7702 	 * "123" is the index of the instruction that was poisoned. We extract
7703 	 * instruction index to find corresponding CO-RE relocation and
7704 	 * replace this part of the log with more relevant information about
7705 	 * failed CO-RE relocation.
7706 	 */
7707 	const struct bpf_core_relo *relo;
7708 	struct bpf_core_spec spec;
7709 	char patch[512], spec_buf[256];
7710 	int insn_idx, err, spec_len;
7711 
7712 	if (sscanf(line1, "%d: (%*d) call unknown#195896080\n", &insn_idx) != 1)
7713 		return;
7714 
7715 	relo = find_relo_core(prog, insn_idx);
7716 	if (!relo)
7717 		return;
7718 
7719 	err = bpf_core_parse_spec(prog->name, prog->obj->btf, relo, &spec);
7720 	if (err)
7721 		return;
7722 
7723 	spec_len = bpf_core_format_spec(spec_buf, sizeof(spec_buf), &spec);
7724 	snprintf(patch, sizeof(patch),
7725 		 "%d: <invalid CO-RE relocation>\n"
7726 		 "failed to resolve CO-RE relocation %s%s\n",
7727 		 insn_idx, spec_buf, spec_len >= sizeof(spec_buf) ? "..." : "");
7728 
7729 	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
7730 }
7731 
fixup_log_missing_map_load(struct bpf_program * prog,char * buf,size_t buf_sz,size_t log_sz,char * line1,char * line2,char * line3)7732 static void fixup_log_missing_map_load(struct bpf_program *prog,
7733 				       char *buf, size_t buf_sz, size_t log_sz,
7734 				       char *line1, char *line2, char *line3)
7735 {
7736 	/* Expected log for failed and not properly guarded map reference:
7737 	 * line1 -> 123: (85) call unknown#2001000345
7738 	 * line2 -> invalid func unknown#2001000345
7739 	 * line3 -> <anything else or end of buffer>
7740 	 *
7741 	 * "123" is the index of the instruction that was poisoned.
7742 	 * "345" in "2001000345" is a map index in obj->maps to fetch map name.
7743 	 */
7744 	struct bpf_object *obj = prog->obj;
7745 	const struct bpf_map *map;
7746 	int insn_idx, map_idx;
7747 	char patch[128];
7748 
7749 	if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
7750 		return;
7751 
7752 	map_idx -= POISON_LDIMM64_MAP_BASE;
7753 	if (map_idx < 0 || map_idx >= obj->nr_maps)
7754 		return;
7755 	map = &obj->maps[map_idx];
7756 
7757 	snprintf(patch, sizeof(patch),
7758 		 "%d: <invalid BPF map reference>\n"
7759 		 "BPF map '%s' is referenced but wasn't created\n",
7760 		 insn_idx, map->name);
7761 
7762 	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
7763 }
7764 
fixup_log_missing_kfunc_call(struct bpf_program * prog,char * buf,size_t buf_sz,size_t log_sz,char * line1,char * line2,char * line3)7765 static void fixup_log_missing_kfunc_call(struct bpf_program *prog,
7766 					 char *buf, size_t buf_sz, size_t log_sz,
7767 					 char *line1, char *line2, char *line3)
7768 {
7769 	/* Expected log for failed and not properly guarded kfunc call:
7770 	 * line1 -> 123: (85) call unknown#2002000345
7771 	 * line2 -> invalid func unknown#2002000345
7772 	 * line3 -> <anything else or end of buffer>
7773 	 *
7774 	 * "123" is the index of the instruction that was poisoned.
7775 	 * "345" in "2002000345" is an extern index in obj->externs to fetch kfunc name.
7776 	 */
7777 	struct bpf_object *obj = prog->obj;
7778 	const struct extern_desc *ext;
7779 	int insn_idx, ext_idx;
7780 	char patch[128];
7781 
7782 	if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &ext_idx) != 2)
7783 		return;
7784 
7785 	ext_idx -= POISON_CALL_KFUNC_BASE;
7786 	if (ext_idx < 0 || ext_idx >= obj->nr_extern)
7787 		return;
7788 	ext = &obj->externs[ext_idx];
7789 
7790 	snprintf(patch, sizeof(patch),
7791 		 "%d: <invalid kfunc call>\n"
7792 		 "kfunc '%s' is referenced but wasn't resolved\n",
7793 		 insn_idx, ext->name);
7794 
7795 	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
7796 }
7797 
fixup_verifier_log(struct bpf_program * prog,char * buf,size_t buf_sz)7798 static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz)
7799 {
7800 	/* look for familiar error patterns in last N lines of the log */
7801 	const size_t max_last_line_cnt = 10;
7802 	char *prev_line, *cur_line, *next_line;
7803 	size_t log_sz;
7804 	int i;
7805 
7806 	if (!buf)
7807 		return;
7808 
7809 	log_sz = strlen(buf) + 1;
7810 	next_line = buf + log_sz - 1;
7811 
7812 	for (i = 0; i < max_last_line_cnt; i++, next_line = cur_line) {
7813 		cur_line = find_prev_line(buf, next_line);
7814 		if (!cur_line)
7815 			return;
7816 
7817 		if (str_has_pfx(cur_line, "invalid func unknown#195896080\n")) {
7818 			prev_line = find_prev_line(buf, cur_line);
7819 			if (!prev_line)
7820 				continue;
7821 
7822 			/* failed CO-RE relocation case */
7823 			fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
7824 						   prev_line, cur_line, next_line);
7825 			return;
7826 		} else if (str_has_pfx(cur_line, "invalid func unknown#"POISON_LDIMM64_MAP_PFX)) {
7827 			prev_line = find_prev_line(buf, cur_line);
7828 			if (!prev_line)
7829 				continue;
7830 
7831 			/* reference to uncreated BPF map */
7832 			fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
7833 						   prev_line, cur_line, next_line);
7834 			return;
7835 		} else if (str_has_pfx(cur_line, "invalid func unknown#"POISON_CALL_KFUNC_PFX)) {
7836 			prev_line = find_prev_line(buf, cur_line);
7837 			if (!prev_line)
7838 				continue;
7839 
7840 			/* reference to unresolved kfunc */
7841 			fixup_log_missing_kfunc_call(prog, buf, buf_sz, log_sz,
7842 						     prev_line, cur_line, next_line);
7843 			return;
7844 		}
7845 	}
7846 }
7847 
bpf_program_record_relos(struct bpf_program * prog)7848 static int bpf_program_record_relos(struct bpf_program *prog)
7849 {
7850 	struct bpf_object *obj = prog->obj;
7851 	int i;
7852 
7853 	for (i = 0; i < prog->nr_reloc; i++) {
7854 		struct reloc_desc *relo = &prog->reloc_desc[i];
7855 		struct extern_desc *ext = &obj->externs[relo->ext_idx];
7856 		int kind;
7857 
7858 		switch (relo->type) {
7859 		case RELO_EXTERN_LD64:
7860 			if (ext->type != EXT_KSYM)
7861 				continue;
7862 			kind = btf_is_var(btf__type_by_id(obj->btf, ext->btf_id)) ?
7863 				BTF_KIND_VAR : BTF_KIND_FUNC;
7864 			bpf_gen__record_extern(obj->gen_loader, ext->name,
7865 					       ext->is_weak, !ext->ksym.type_id,
7866 					       true, kind, relo->insn_idx);
7867 			break;
7868 		case RELO_EXTERN_CALL:
7869 			bpf_gen__record_extern(obj->gen_loader, ext->name,
7870 					       ext->is_weak, false, false, BTF_KIND_FUNC,
7871 					       relo->insn_idx);
7872 			break;
7873 		case RELO_CORE: {
7874 			struct bpf_core_relo cr = {
7875 				.insn_off = relo->insn_idx * 8,
7876 				.type_id = relo->core_relo->type_id,
7877 				.access_str_off = relo->core_relo->access_str_off,
7878 				.kind = relo->core_relo->kind,
7879 			};
7880 
7881 			bpf_gen__record_relo_core(obj->gen_loader, &cr);
7882 			break;
7883 		}
7884 		default:
7885 			continue;
7886 		}
7887 	}
7888 	return 0;
7889 }
7890 
7891 static int
bpf_object__load_progs(struct bpf_object * obj,int log_level)7892 bpf_object__load_progs(struct bpf_object *obj, int log_level)
7893 {
7894 	struct bpf_program *prog;
7895 	size_t i;
7896 	int err;
7897 
7898 	for (i = 0; i < obj->nr_programs; i++) {
7899 		prog = &obj->programs[i];
7900 		err = bpf_object__sanitize_prog(obj, prog);
7901 		if (err)
7902 			return err;
7903 	}
7904 
7905 	for (i = 0; i < obj->nr_programs; i++) {
7906 		prog = &obj->programs[i];
7907 		if (prog_is_subprog(obj, prog))
7908 			continue;
7909 		if (!prog->autoload) {
7910 			pr_debug("prog '%s': skipped loading\n", prog->name);
7911 			continue;
7912 		}
7913 		prog->log_level |= log_level;
7914 
7915 		if (obj->gen_loader)
7916 			bpf_program_record_relos(prog);
7917 
7918 		err = bpf_object_load_prog(obj, prog, prog->insns, prog->insns_cnt,
7919 					   obj->license, obj->kern_version, &prog->fd);
7920 		if (err) {
7921 			pr_warn("prog '%s': failed to load: %s\n", prog->name, errstr(err));
7922 			return err;
7923 		}
7924 	}
7925 
7926 	bpf_object__free_relocs(obj);
7927 	return 0;
7928 }
7929 
7930 static const struct bpf_sec_def *find_sec_def(const char *sec_name);
7931 
bpf_object_init_progs(struct bpf_object * obj,const struct bpf_object_open_opts * opts)7932 static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object_open_opts *opts)
7933 {
7934 	struct bpf_program *prog;
7935 	int err;
7936 
7937 	bpf_object__for_each_program(prog, obj) {
7938 		prog->sec_def = find_sec_def(prog->sec_name);
7939 		if (!prog->sec_def) {
7940 			/* couldn't guess, but user might manually specify */
7941 			pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
7942 				prog->name, prog->sec_name);
7943 			continue;
7944 		}
7945 
7946 		prog->type = prog->sec_def->prog_type;
7947 		prog->expected_attach_type = prog->sec_def->expected_attach_type;
7948 
7949 		/* sec_def can have custom callback which should be called
7950 		 * after bpf_program is initialized to adjust its properties
7951 		 */
7952 		if (prog->sec_def->prog_setup_fn) {
7953 			err = prog->sec_def->prog_setup_fn(prog, prog->sec_def->cookie);
7954 			if (err < 0) {
7955 				pr_warn("prog '%s': failed to initialize: %s\n",
7956 					prog->name, errstr(err));
7957 				return err;
7958 			}
7959 		}
7960 	}
7961 
7962 	return 0;
7963 }
7964 
bpf_object_open(const char * path,const void * obj_buf,size_t obj_buf_sz,const char * obj_name,const struct bpf_object_open_opts * opts)7965 static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, size_t obj_buf_sz,
7966 					  const char *obj_name,
7967 					  const struct bpf_object_open_opts *opts)
7968 {
7969 	const char *kconfig, *btf_tmp_path, *token_path;
7970 	struct bpf_object *obj;
7971 	int err;
7972 	char *log_buf;
7973 	size_t log_size;
7974 	__u32 log_level;
7975 
7976 	if (obj_buf && !obj_name)
7977 		return ERR_PTR(-EINVAL);
7978 
7979 	if (elf_version(EV_CURRENT) == EV_NONE) {
7980 		pr_warn("failed to init libelf for %s\n",
7981 			path ? : "(mem buf)");
7982 		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
7983 	}
7984 
7985 	if (!OPTS_VALID(opts, bpf_object_open_opts))
7986 		return ERR_PTR(-EINVAL);
7987 
7988 	obj_name = OPTS_GET(opts, object_name, NULL) ?: obj_name;
7989 	if (obj_buf) {
7990 		path = obj_name;
7991 		pr_debug("loading object '%s' from buffer\n", obj_name);
7992 	} else {
7993 		pr_debug("loading object from %s\n", path);
7994 	}
7995 
7996 	log_buf = OPTS_GET(opts, kernel_log_buf, NULL);
7997 	log_size = OPTS_GET(opts, kernel_log_size, 0);
7998 	log_level = OPTS_GET(opts, kernel_log_level, 0);
7999 	if (log_size > UINT_MAX)
8000 		return ERR_PTR(-EINVAL);
8001 	if (log_size && !log_buf)
8002 		return ERR_PTR(-EINVAL);
8003 
8004 	token_path = OPTS_GET(opts, bpf_token_path, NULL);
8005 	/* if user didn't specify bpf_token_path explicitly, check if
8006 	 * LIBBPF_BPF_TOKEN_PATH envvar was set and treat it as bpf_token_path
8007 	 * option
8008 	 */
8009 	if (!token_path)
8010 		token_path = getenv("LIBBPF_BPF_TOKEN_PATH");
8011 	if (token_path && strlen(token_path) >= PATH_MAX)
8012 		return ERR_PTR(-ENAMETOOLONG);
8013 
8014 	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
8015 	if (IS_ERR(obj))
8016 		return obj;
8017 
8018 	obj->log_buf = log_buf;
8019 	obj->log_size = log_size;
8020 	obj->log_level = log_level;
8021 
8022 	if (token_path) {
8023 		obj->token_path = strdup(token_path);
8024 		if (!obj->token_path) {
8025 			err = -ENOMEM;
8026 			goto out;
8027 		}
8028 	}
8029 
8030 	btf_tmp_path = OPTS_GET(opts, btf_custom_path, NULL);
8031 	if (btf_tmp_path) {
8032 		if (strlen(btf_tmp_path) >= PATH_MAX) {
8033 			err = -ENAMETOOLONG;
8034 			goto out;
8035 		}
8036 		obj->btf_custom_path = strdup(btf_tmp_path);
8037 		if (!obj->btf_custom_path) {
8038 			err = -ENOMEM;
8039 			goto out;
8040 		}
8041 	}
8042 
8043 	kconfig = OPTS_GET(opts, kconfig, NULL);
8044 	if (kconfig) {
8045 		obj->kconfig = strdup(kconfig);
8046 		if (!obj->kconfig) {
8047 			err = -ENOMEM;
8048 			goto out;
8049 		}
8050 	}
8051 
8052 	err = bpf_object__elf_init(obj);
8053 	err = err ? : bpf_object__elf_collect(obj);
8054 	err = err ? : bpf_object__collect_externs(obj);
8055 	err = err ? : bpf_object_fixup_btf(obj);
8056 	err = err ? : bpf_object__init_maps(obj, opts);
8057 	err = err ? : bpf_object_init_progs(obj, opts);
8058 	err = err ? : bpf_object__collect_relos(obj);
8059 	if (err)
8060 		goto out;
8061 
8062 	bpf_object__elf_finish(obj);
8063 
8064 	return obj;
8065 out:
8066 	bpf_object__close(obj);
8067 	return ERR_PTR(err);
8068 }
8069 
8070 struct bpf_object *
bpf_object__open_file(const char * path,const struct bpf_object_open_opts * opts)8071 bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
8072 {
8073 	if (!path)
8074 		return libbpf_err_ptr(-EINVAL);
8075 
8076 	return libbpf_ptr(bpf_object_open(path, NULL, 0, NULL, opts));
8077 }
8078 
bpf_object__open(const char * path)8079 struct bpf_object *bpf_object__open(const char *path)
8080 {
8081 	return bpf_object__open_file(path, NULL);
8082 }
8083 
8084 struct bpf_object *
bpf_object__open_mem(const void * obj_buf,size_t obj_buf_sz,const struct bpf_object_open_opts * opts)8085 bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
8086 		     const struct bpf_object_open_opts *opts)
8087 {
8088 	char tmp_name[64];
8089 
8090 	if (!obj_buf || obj_buf_sz == 0)
8091 		return libbpf_err_ptr(-EINVAL);
8092 
8093 	/* create a (quite useless) default "name" for this memory buffer object */
8094 	snprintf(tmp_name, sizeof(tmp_name), "%lx-%zx", (unsigned long)obj_buf, obj_buf_sz);
8095 
8096 	return libbpf_ptr(bpf_object_open(NULL, obj_buf, obj_buf_sz, tmp_name, opts));
8097 }
8098 
bpf_object_unload(struct bpf_object * obj)8099 static int bpf_object_unload(struct bpf_object *obj)
8100 {
8101 	size_t i;
8102 
8103 	if (!obj)
8104 		return libbpf_err(-EINVAL);
8105 
8106 	for (i = 0; i < obj->nr_maps; i++) {
8107 		zclose(obj->maps[i].fd);
8108 		if (obj->maps[i].st_ops)
8109 			zfree(&obj->maps[i].st_ops->kern_vdata);
8110 	}
8111 
8112 	for (i = 0; i < obj->nr_programs; i++)
8113 		bpf_program__unload(&obj->programs[i]);
8114 
8115 	return 0;
8116 }
8117 
bpf_object__sanitize_maps(struct bpf_object * obj)8118 static int bpf_object__sanitize_maps(struct bpf_object *obj)
8119 {
8120 	struct bpf_map *m;
8121 
8122 	bpf_object__for_each_map(m, obj) {
8123 		if (!bpf_map__is_internal(m))
8124 			continue;
8125 		if (!kernel_supports(obj, FEAT_ARRAY_MMAP))
8126 			m->def.map_flags &= ~BPF_F_MMAPABLE;
8127 	}
8128 
8129 	return 0;
8130 }
8131 
8132 typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type,
8133 			     const char *sym_name, void *ctx);
8134 
libbpf_kallsyms_parse(kallsyms_cb_t cb,void * ctx)8135 static int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
8136 {
8137 	char sym_type, sym_name[500];
8138 	unsigned long long sym_addr;
8139 	int ret, err = 0;
8140 	FILE *f;
8141 
8142 	f = fopen("/proc/kallsyms", "re");
8143 	if (!f) {
8144 		err = -errno;
8145 		pr_warn("failed to open /proc/kallsyms: %s\n", errstr(err));
8146 		return err;
8147 	}
8148 
8149 	while (true) {
8150 		ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
8151 			     &sym_addr, &sym_type, sym_name);
8152 		if (ret == EOF && feof(f))
8153 			break;
8154 		if (ret != 3) {
8155 			pr_warn("failed to read kallsyms entry: %d\n", ret);
8156 			err = -EINVAL;
8157 			break;
8158 		}
8159 
8160 		err = cb(sym_addr, sym_type, sym_name, ctx);
8161 		if (err)
8162 			break;
8163 	}
8164 
8165 	fclose(f);
8166 	return err;
8167 }
8168 
kallsyms_cb(unsigned long long sym_addr,char sym_type,const char * sym_name,void * ctx)8169 static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
8170 		       const char *sym_name, void *ctx)
8171 {
8172 	struct bpf_object *obj = ctx;
8173 	const struct btf_type *t;
8174 	struct extern_desc *ext;
8175 	char *res;
8176 
8177 	res = strstr(sym_name, ".llvm.");
8178 	if (sym_type == 'd' && res)
8179 		ext = find_extern_by_name_with_len(obj, sym_name, res - sym_name);
8180 	else
8181 		ext = find_extern_by_name(obj, sym_name);
8182 	if (!ext || ext->type != EXT_KSYM)
8183 		return 0;
8184 
8185 	t = btf__type_by_id(obj->btf, ext->btf_id);
8186 	if (!btf_is_var(t))
8187 		return 0;
8188 
8189 	if (ext->is_set && ext->ksym.addr != sym_addr) {
8190 		pr_warn("extern (ksym) '%s': resolution is ambiguous: 0x%llx or 0x%llx\n",
8191 			sym_name, ext->ksym.addr, sym_addr);
8192 		return -EINVAL;
8193 	}
8194 	if (!ext->is_set) {
8195 		ext->is_set = true;
8196 		ext->ksym.addr = sym_addr;
8197 		pr_debug("extern (ksym) '%s': set to 0x%llx\n", sym_name, sym_addr);
8198 	}
8199 	return 0;
8200 }
8201 
bpf_object__read_kallsyms_file(struct bpf_object * obj)8202 static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
8203 {
8204 	return libbpf_kallsyms_parse(kallsyms_cb, obj);
8205 }
8206 
find_ksym_btf_id(struct bpf_object * obj,const char * ksym_name,__u16 kind,struct btf ** res_btf,struct module_btf ** res_mod_btf)8207 static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
8208 			    __u16 kind, struct btf **res_btf,
8209 			    struct module_btf **res_mod_btf)
8210 {
8211 	struct module_btf *mod_btf;
8212 	struct btf *btf;
8213 	int i, id, err;
8214 
8215 	btf = obj->btf_vmlinux;
8216 	mod_btf = NULL;
8217 	id = btf__find_by_name_kind(btf, ksym_name, kind);
8218 
8219 	if (id == -ENOENT) {
8220 		err = load_module_btfs(obj);
8221 		if (err)
8222 			return err;
8223 
8224 		for (i = 0; i < obj->btf_module_cnt; i++) {
8225 			/* we assume module_btf's BTF FD is always >0 */
8226 			mod_btf = &obj->btf_modules[i];
8227 			btf = mod_btf->btf;
8228 			id = btf__find_by_name_kind_own(btf, ksym_name, kind);
8229 			if (id != -ENOENT)
8230 				break;
8231 		}
8232 	}
8233 	if (id <= 0)
8234 		return -ESRCH;
8235 
8236 	*res_btf = btf;
8237 	*res_mod_btf = mod_btf;
8238 	return id;
8239 }
8240 
bpf_object__resolve_ksym_var_btf_id(struct bpf_object * obj,struct extern_desc * ext)8241 static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
8242 					       struct extern_desc *ext)
8243 {
8244 	const struct btf_type *targ_var, *targ_type;
8245 	__u32 targ_type_id, local_type_id;
8246 	struct module_btf *mod_btf = NULL;
8247 	const char *targ_var_name;
8248 	struct btf *btf = NULL;
8249 	int id, err;
8250 
8251 	id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &mod_btf);
8252 	if (id < 0) {
8253 		if (id == -ESRCH && ext->is_weak)
8254 			return 0;
8255 		pr_warn("extern (var ksym) '%s': not found in kernel BTF\n",
8256 			ext->name);
8257 		return id;
8258 	}
8259 
8260 	/* find local type_id */
8261 	local_type_id = ext->ksym.type_id;
8262 
8263 	/* find target type_id */
8264 	targ_var = btf__type_by_id(btf, id);
8265 	targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
8266 	targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
8267 
8268 	err = bpf_core_types_are_compat(obj->btf, local_type_id,
8269 					btf, targ_type_id);
8270 	if (err <= 0) {
8271 		const struct btf_type *local_type;
8272 		const char *targ_name, *local_name;
8273 
8274 		local_type = btf__type_by_id(obj->btf, local_type_id);
8275 		local_name = btf__name_by_offset(obj->btf, local_type->name_off);
8276 		targ_name = btf__name_by_offset(btf, targ_type->name_off);
8277 
8278 		pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
8279 			ext->name, local_type_id,
8280 			btf_kind_str(local_type), local_name, targ_type_id,
8281 			btf_kind_str(targ_type), targ_name);
8282 		return -EINVAL;
8283 	}
8284 
8285 	ext->is_set = true;
8286 	ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0;
8287 	ext->ksym.kernel_btf_id = id;
8288 	pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n",
8289 		 ext->name, id, btf_kind_str(targ_var), targ_var_name);
8290 
8291 	return 0;
8292 }
8293 
bpf_object__resolve_ksym_func_btf_id(struct bpf_object * obj,struct extern_desc * ext)8294 static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
8295 						struct extern_desc *ext)
8296 {
8297 	int local_func_proto_id, kfunc_proto_id, kfunc_id;
8298 	struct module_btf *mod_btf = NULL;
8299 	const struct btf_type *kern_func;
8300 	struct btf *kern_btf = NULL;
8301 	int ret;
8302 
8303 	local_func_proto_id = ext->ksym.type_id;
8304 
8305 	kfunc_id = find_ksym_btf_id(obj, ext->essent_name ?: ext->name, BTF_KIND_FUNC, &kern_btf,
8306 				    &mod_btf);
8307 	if (kfunc_id < 0) {
8308 		if (kfunc_id == -ESRCH && ext->is_weak)
8309 			return 0;
8310 		pr_warn("extern (func ksym) '%s': not found in kernel or module BTFs\n",
8311 			ext->name);
8312 		return kfunc_id;
8313 	}
8314 
8315 	kern_func = btf__type_by_id(kern_btf, kfunc_id);
8316 	kfunc_proto_id = kern_func->type;
8317 
8318 	ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
8319 					kern_btf, kfunc_proto_id);
8320 	if (ret <= 0) {
8321 		if (ext->is_weak)
8322 			return 0;
8323 
8324 		pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with %s [%d]\n",
8325 			ext->name, local_func_proto_id,
8326 			mod_btf ? mod_btf->name : "vmlinux", kfunc_proto_id);
8327 		return -EINVAL;
8328 	}
8329 
8330 	/* set index for module BTF fd in fd_array, if unset */
8331 	if (mod_btf && !mod_btf->fd_array_idx) {
8332 		/* insn->off is s16 */
8333 		if (obj->fd_array_cnt == INT16_MAX) {
8334 			pr_warn("extern (func ksym) '%s': module BTF fd index %d too big to fit in bpf_insn offset\n",
8335 				ext->name, mod_btf->fd_array_idx);
8336 			return -E2BIG;
8337 		}
8338 		/* Cannot use index 0 for module BTF fd */
8339 		if (!obj->fd_array_cnt)
8340 			obj->fd_array_cnt = 1;
8341 
8342 		ret = libbpf_ensure_mem((void **)&obj->fd_array, &obj->fd_array_cap, sizeof(int),
8343 					obj->fd_array_cnt + 1);
8344 		if (ret)
8345 			return ret;
8346 		mod_btf->fd_array_idx = obj->fd_array_cnt;
8347 		/* we assume module BTF FD is always >0 */
8348 		obj->fd_array[obj->fd_array_cnt++] = mod_btf->fd;
8349 	}
8350 
8351 	ext->is_set = true;
8352 	ext->ksym.kernel_btf_id = kfunc_id;
8353 	ext->ksym.btf_fd_idx = mod_btf ? mod_btf->fd_array_idx : 0;
8354 	/* Also set kernel_btf_obj_fd to make sure that bpf_object__relocate_data()
8355 	 * populates FD into ld_imm64 insn when it's used to point to kfunc.
8356 	 * {kernel_btf_id, btf_fd_idx} -> fixup bpf_call.
8357 	 * {kernel_btf_id, kernel_btf_obj_fd} -> fixup ld_imm64.
8358 	 */
8359 	ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0;
8360 	pr_debug("extern (func ksym) '%s': resolved to %s [%d]\n",
8361 		 ext->name, mod_btf ? mod_btf->name : "vmlinux", kfunc_id);
8362 
8363 	return 0;
8364 }
8365 
bpf_object__resolve_ksyms_btf_id(struct bpf_object * obj)8366 static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
8367 {
8368 	const struct btf_type *t;
8369 	struct extern_desc *ext;
8370 	int i, err;
8371 
8372 	for (i = 0; i < obj->nr_extern; i++) {
8373 		ext = &obj->externs[i];
8374 		if (ext->type != EXT_KSYM || !ext->ksym.type_id)
8375 			continue;
8376 
8377 		if (obj->gen_loader) {
8378 			ext->is_set = true;
8379 			ext->ksym.kernel_btf_obj_fd = 0;
8380 			ext->ksym.kernel_btf_id = 0;
8381 			continue;
8382 		}
8383 		t = btf__type_by_id(obj->btf, ext->btf_id);
8384 		if (btf_is_var(t))
8385 			err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
8386 		else
8387 			err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
8388 		if (err)
8389 			return err;
8390 	}
8391 	return 0;
8392 }
8393 
bpf_object__resolve_externs(struct bpf_object * obj,const char * extra_kconfig)8394 static int bpf_object__resolve_externs(struct bpf_object *obj,
8395 				       const char *extra_kconfig)
8396 {
8397 	bool need_config = false, need_kallsyms = false;
8398 	bool need_vmlinux_btf = false;
8399 	struct extern_desc *ext;
8400 	void *kcfg_data = NULL;
8401 	int err, i;
8402 
8403 	if (obj->nr_extern == 0)
8404 		return 0;
8405 
8406 	if (obj->kconfig_map_idx >= 0)
8407 		kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped;
8408 
8409 	for (i = 0; i < obj->nr_extern; i++) {
8410 		ext = &obj->externs[i];
8411 
8412 		if (ext->type == EXT_KSYM) {
8413 			if (ext->ksym.type_id)
8414 				need_vmlinux_btf = true;
8415 			else
8416 				need_kallsyms = true;
8417 			continue;
8418 		} else if (ext->type == EXT_KCFG) {
8419 			void *ext_ptr = kcfg_data + ext->kcfg.data_off;
8420 			__u64 value = 0;
8421 
8422 			/* Kconfig externs need actual /proc/config.gz */
8423 			if (str_has_pfx(ext->name, "CONFIG_")) {
8424 				need_config = true;
8425 				continue;
8426 			}
8427 
8428 			/* Virtual kcfg externs are customly handled by libbpf */
8429 			if (strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
8430 				value = get_kernel_version();
8431 				if (!value) {
8432 					pr_warn("extern (kcfg) '%s': failed to get kernel version\n", ext->name);
8433 					return -EINVAL;
8434 				}
8435 			} else if (strcmp(ext->name, "LINUX_HAS_BPF_COOKIE") == 0) {
8436 				value = kernel_supports(obj, FEAT_BPF_COOKIE);
8437 			} else if (strcmp(ext->name, "LINUX_HAS_SYSCALL_WRAPPER") == 0) {
8438 				value = kernel_supports(obj, FEAT_SYSCALL_WRAPPER);
8439 			} else if (!str_has_pfx(ext->name, "LINUX_") || !ext->is_weak) {
8440 				/* Currently libbpf supports only CONFIG_ and LINUX_ prefixed
8441 				 * __kconfig externs, where LINUX_ ones are virtual and filled out
8442 				 * customly by libbpf (their values don't come from Kconfig).
8443 				 * If LINUX_xxx variable is not recognized by libbpf, but is marked
8444 				 * __weak, it defaults to zero value, just like for CONFIG_xxx
8445 				 * externs.
8446 				 */
8447 				pr_warn("extern (kcfg) '%s': unrecognized virtual extern\n", ext->name);
8448 				return -EINVAL;
8449 			}
8450 
8451 			err = set_kcfg_value_num(ext, ext_ptr, value);
8452 			if (err)
8453 				return err;
8454 			pr_debug("extern (kcfg) '%s': set to 0x%llx\n",
8455 				 ext->name, (long long)value);
8456 		} else {
8457 			pr_warn("extern '%s': unrecognized extern kind\n", ext->name);
8458 			return -EINVAL;
8459 		}
8460 	}
8461 	if (need_config && extra_kconfig) {
8462 		err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data);
8463 		if (err)
8464 			return -EINVAL;
8465 		need_config = false;
8466 		for (i = 0; i < obj->nr_extern; i++) {
8467 			ext = &obj->externs[i];
8468 			if (ext->type == EXT_KCFG && !ext->is_set) {
8469 				need_config = true;
8470 				break;
8471 			}
8472 		}
8473 	}
8474 	if (need_config) {
8475 		err = bpf_object__read_kconfig_file(obj, kcfg_data);
8476 		if (err)
8477 			return -EINVAL;
8478 	}
8479 	if (need_kallsyms) {
8480 		err = bpf_object__read_kallsyms_file(obj);
8481 		if (err)
8482 			return -EINVAL;
8483 	}
8484 	if (need_vmlinux_btf) {
8485 		err = bpf_object__resolve_ksyms_btf_id(obj);
8486 		if (err)
8487 			return -EINVAL;
8488 	}
8489 	for (i = 0; i < obj->nr_extern; i++) {
8490 		ext = &obj->externs[i];
8491 
8492 		if (!ext->is_set && !ext->is_weak) {
8493 			pr_warn("extern '%s' (strong): not resolved\n", ext->name);
8494 			return -ESRCH;
8495 		} else if (!ext->is_set) {
8496 			pr_debug("extern '%s' (weak): not resolved, defaulting to zero\n",
8497 				 ext->name);
8498 		}
8499 	}
8500 
8501 	return 0;
8502 }
8503 
bpf_map_prepare_vdata(const struct bpf_map * map)8504 static void bpf_map_prepare_vdata(const struct bpf_map *map)
8505 {
8506 	const struct btf_type *type;
8507 	struct bpf_struct_ops *st_ops;
8508 	__u32 i;
8509 
8510 	st_ops = map->st_ops;
8511 	type = btf__type_by_id(map->obj->btf, st_ops->type_id);
8512 	for (i = 0; i < btf_vlen(type); i++) {
8513 		struct bpf_program *prog = st_ops->progs[i];
8514 		void *kern_data;
8515 		int prog_fd;
8516 
8517 		if (!prog)
8518 			continue;
8519 
8520 		prog_fd = bpf_program__fd(prog);
8521 		kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
8522 		*(unsigned long *)kern_data = prog_fd;
8523 	}
8524 }
8525 
bpf_object_prepare_struct_ops(struct bpf_object * obj)8526 static int bpf_object_prepare_struct_ops(struct bpf_object *obj)
8527 {
8528 	struct bpf_map *map;
8529 	int i;
8530 
8531 	for (i = 0; i < obj->nr_maps; i++) {
8532 		map = &obj->maps[i];
8533 
8534 		if (!bpf_map__is_struct_ops(map))
8535 			continue;
8536 
8537 		if (!map->autocreate)
8538 			continue;
8539 
8540 		bpf_map_prepare_vdata(map);
8541 	}
8542 
8543 	return 0;
8544 }
8545 
bpf_object_load(struct bpf_object * obj,int extra_log_level,const char * target_btf_path)8546 static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const char *target_btf_path)
8547 {
8548 	int err, i;
8549 
8550 	if (!obj)
8551 		return libbpf_err(-EINVAL);
8552 
8553 	if (obj->loaded) {
8554 		pr_warn("object '%s': load can't be attempted twice\n", obj->name);
8555 		return libbpf_err(-EINVAL);
8556 	}
8557 
8558 	/* Disallow kernel loading programs of non-native endianness but
8559 	 * permit cross-endian creation of "light skeleton".
8560 	 */
8561 	if (obj->gen_loader) {
8562 		bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps);
8563 	} else if (!is_native_endianness(obj)) {
8564 		pr_warn("object '%s': loading non-native endianness is unsupported\n", obj->name);
8565 		return libbpf_err(-LIBBPF_ERRNO__ENDIAN);
8566 	}
8567 
8568 	err = bpf_object_prepare_token(obj);
8569 	err = err ? : bpf_object__probe_loading(obj);
8570 	err = err ? : bpf_object__load_vmlinux_btf(obj, false);
8571 	err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
8572 	err = err ? : bpf_object__sanitize_maps(obj);
8573 	err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
8574 	err = err ? : bpf_object_adjust_struct_ops_autoload(obj);
8575 	err = err ? : bpf_object__relocate(obj, obj->btf_custom_path ? : target_btf_path);
8576 	err = err ? : bpf_object__sanitize_and_load_btf(obj);
8577 	err = err ? : bpf_object__create_maps(obj);
8578 	err = err ? : bpf_object__load_progs(obj, extra_log_level);
8579 	err = err ? : bpf_object_init_prog_arrays(obj);
8580 	err = err ? : bpf_object_prepare_struct_ops(obj);
8581 
8582 	if (obj->gen_loader) {
8583 		/* reset FDs */
8584 		if (obj->btf)
8585 			btf__set_fd(obj->btf, -1);
8586 		if (!err)
8587 			err = bpf_gen__finish(obj->gen_loader, obj->nr_programs, obj->nr_maps);
8588 	}
8589 
8590 	/* clean up fd_array */
8591 	zfree(&obj->fd_array);
8592 
8593 	/* clean up module BTFs */
8594 	for (i = 0; i < obj->btf_module_cnt; i++) {
8595 		close(obj->btf_modules[i].fd);
8596 		btf__free(obj->btf_modules[i].btf);
8597 		free(obj->btf_modules[i].name);
8598 	}
8599 	free(obj->btf_modules);
8600 
8601 	/* clean up vmlinux BTF */
8602 	btf__free(obj->btf_vmlinux);
8603 	obj->btf_vmlinux = NULL;
8604 
8605 	obj->loaded = true; /* doesn't matter if successfully or not */
8606 
8607 	if (err)
8608 		goto out;
8609 
8610 	return 0;
8611 out:
8612 	/* unpin any maps that were auto-pinned during load */
8613 	for (i = 0; i < obj->nr_maps; i++)
8614 		if (obj->maps[i].pinned && !obj->maps[i].reused)
8615 			bpf_map__unpin(&obj->maps[i], NULL);
8616 
8617 	bpf_object_unload(obj);
8618 	pr_warn("failed to load object '%s'\n", obj->path);
8619 	return libbpf_err(err);
8620 }
8621 
bpf_object__load(struct bpf_object * obj)8622 int bpf_object__load(struct bpf_object *obj)
8623 {
8624 	return bpf_object_load(obj, 0, NULL);
8625 }
8626 
make_parent_dir(const char * path)8627 static int make_parent_dir(const char *path)
8628 {
8629 	char *dname, *dir;
8630 	int err = 0;
8631 
8632 	dname = strdup(path);
8633 	if (dname == NULL)
8634 		return -ENOMEM;
8635 
8636 	dir = dirname(dname);
8637 	if (mkdir(dir, 0700) && errno != EEXIST)
8638 		err = -errno;
8639 
8640 	free(dname);
8641 	if (err) {
8642 		pr_warn("failed to mkdir %s: %s\n", path, errstr(err));
8643 	}
8644 	return err;
8645 }
8646 
check_path(const char * path)8647 static int check_path(const char *path)
8648 {
8649 	struct statfs st_fs;
8650 	char *dname, *dir;
8651 	int err = 0;
8652 
8653 	if (path == NULL)
8654 		return -EINVAL;
8655 
8656 	dname = strdup(path);
8657 	if (dname == NULL)
8658 		return -ENOMEM;
8659 
8660 	dir = dirname(dname);
8661 	if (statfs(dir, &st_fs)) {
8662 		pr_warn("failed to statfs %s: %s\n", dir, errstr(errno));
8663 		err = -errno;
8664 	}
8665 	free(dname);
8666 
8667 	if (!err && st_fs.f_type != BPF_FS_MAGIC) {
8668 		pr_warn("specified path %s is not on BPF FS\n", path);
8669 		err = -EINVAL;
8670 	}
8671 
8672 	return err;
8673 }
8674 
bpf_program__pin(struct bpf_program * prog,const char * path)8675 int bpf_program__pin(struct bpf_program *prog, const char *path)
8676 {
8677 	int err;
8678 
8679 	if (prog->fd < 0) {
8680 		pr_warn("prog '%s': can't pin program that wasn't loaded\n", prog->name);
8681 		return libbpf_err(-EINVAL);
8682 	}
8683 
8684 	err = make_parent_dir(path);
8685 	if (err)
8686 		return libbpf_err(err);
8687 
8688 	err = check_path(path);
8689 	if (err)
8690 		return libbpf_err(err);
8691 
8692 	if (bpf_obj_pin(prog->fd, path)) {
8693 		err = -errno;
8694 		pr_warn("prog '%s': failed to pin at '%s': %s\n", prog->name, path, errstr(err));
8695 		return libbpf_err(err);
8696 	}
8697 
8698 	pr_debug("prog '%s': pinned at '%s'\n", prog->name, path);
8699 	return 0;
8700 }
8701 
bpf_program__unpin(struct bpf_program * prog,const char * path)8702 int bpf_program__unpin(struct bpf_program *prog, const char *path)
8703 {
8704 	int err;
8705 
8706 	if (prog->fd < 0) {
8707 		pr_warn("prog '%s': can't unpin program that wasn't loaded\n", prog->name);
8708 		return libbpf_err(-EINVAL);
8709 	}
8710 
8711 	err = check_path(path);
8712 	if (err)
8713 		return libbpf_err(err);
8714 
8715 	err = unlink(path);
8716 	if (err)
8717 		return libbpf_err(-errno);
8718 
8719 	pr_debug("prog '%s': unpinned from '%s'\n", prog->name, path);
8720 	return 0;
8721 }
8722 
bpf_map__pin(struct bpf_map * map,const char * path)8723 int bpf_map__pin(struct bpf_map *map, const char *path)
8724 {
8725 	int err;
8726 
8727 	if (map == NULL) {
8728 		pr_warn("invalid map pointer\n");
8729 		return libbpf_err(-EINVAL);
8730 	}
8731 
8732 	if (map->fd < 0) {
8733 		pr_warn("map '%s': can't pin BPF map without FD (was it created?)\n", map->name);
8734 		return libbpf_err(-EINVAL);
8735 	}
8736 
8737 	if (map->pin_path) {
8738 		if (path && strcmp(path, map->pin_path)) {
8739 			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
8740 				bpf_map__name(map), map->pin_path, path);
8741 			return libbpf_err(-EINVAL);
8742 		} else if (map->pinned) {
8743 			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
8744 				 bpf_map__name(map), map->pin_path);
8745 			return 0;
8746 		}
8747 	} else {
8748 		if (!path) {
8749 			pr_warn("missing a path to pin map '%s' at\n",
8750 				bpf_map__name(map));
8751 			return libbpf_err(-EINVAL);
8752 		} else if (map->pinned) {
8753 			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
8754 			return libbpf_err(-EEXIST);
8755 		}
8756 
8757 		map->pin_path = strdup(path);
8758 		if (!map->pin_path) {
8759 			err = -errno;
8760 			goto out_err;
8761 		}
8762 	}
8763 
8764 	err = make_parent_dir(map->pin_path);
8765 	if (err)
8766 		return libbpf_err(err);
8767 
8768 	err = check_path(map->pin_path);
8769 	if (err)
8770 		return libbpf_err(err);
8771 
8772 	if (bpf_obj_pin(map->fd, map->pin_path)) {
8773 		err = -errno;
8774 		goto out_err;
8775 	}
8776 
8777 	map->pinned = true;
8778 	pr_debug("pinned map '%s'\n", map->pin_path);
8779 
8780 	return 0;
8781 
8782 out_err:
8783 	pr_warn("failed to pin map: %s\n", errstr(err));
8784 	return libbpf_err(err);
8785 }
8786 
bpf_map__unpin(struct bpf_map * map,const char * path)8787 int bpf_map__unpin(struct bpf_map *map, const char *path)
8788 {
8789 	int err;
8790 
8791 	if (map == NULL) {
8792 		pr_warn("invalid map pointer\n");
8793 		return libbpf_err(-EINVAL);
8794 	}
8795 
8796 	if (map->pin_path) {
8797 		if (path && strcmp(path, map->pin_path)) {
8798 			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
8799 				bpf_map__name(map), map->pin_path, path);
8800 			return libbpf_err(-EINVAL);
8801 		}
8802 		path = map->pin_path;
8803 	} else if (!path) {
8804 		pr_warn("no path to unpin map '%s' from\n",
8805 			bpf_map__name(map));
8806 		return libbpf_err(-EINVAL);
8807 	}
8808 
8809 	err = check_path(path);
8810 	if (err)
8811 		return libbpf_err(err);
8812 
8813 	err = unlink(path);
8814 	if (err != 0)
8815 		return libbpf_err(-errno);
8816 
8817 	map->pinned = false;
8818 	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
8819 
8820 	return 0;
8821 }
8822 
bpf_map__set_pin_path(struct bpf_map * map,const char * path)8823 int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
8824 {
8825 	char *new = NULL;
8826 
8827 	if (path) {
8828 		new = strdup(path);
8829 		if (!new)
8830 			return libbpf_err(-errno);
8831 	}
8832 
8833 	free(map->pin_path);
8834 	map->pin_path = new;
8835 	return 0;
8836 }
8837 
8838 __alias(bpf_map__pin_path)
8839 const char *bpf_map__get_pin_path(const struct bpf_map *map);
8840 
bpf_map__pin_path(const struct bpf_map * map)8841 const char *bpf_map__pin_path(const struct bpf_map *map)
8842 {
8843 	return map->pin_path;
8844 }
8845 
bpf_map__is_pinned(const struct bpf_map * map)8846 bool bpf_map__is_pinned(const struct bpf_map *map)
8847 {
8848 	return map->pinned;
8849 }
8850 
sanitize_pin_path(char * s)8851 static void sanitize_pin_path(char *s)
8852 {
8853 	/* bpffs disallows periods in path names */
8854 	while (*s) {
8855 		if (*s == '.')
8856 			*s = '_';
8857 		s++;
8858 	}
8859 }
8860 
bpf_object__pin_maps(struct bpf_object * obj,const char * path)8861 int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
8862 {
8863 	struct bpf_map *map;
8864 	int err;
8865 
8866 	if (!obj)
8867 		return libbpf_err(-ENOENT);
8868 
8869 	if (!obj->loaded) {
8870 		pr_warn("object not yet loaded; load it first\n");
8871 		return libbpf_err(-ENOENT);
8872 	}
8873 
8874 	bpf_object__for_each_map(map, obj) {
8875 		char *pin_path = NULL;
8876 		char buf[PATH_MAX];
8877 
8878 		if (!map->autocreate)
8879 			continue;
8880 
8881 		if (path) {
8882 			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
8883 			if (err)
8884 				goto err_unpin_maps;
8885 			sanitize_pin_path(buf);
8886 			pin_path = buf;
8887 		} else if (!map->pin_path) {
8888 			continue;
8889 		}
8890 
8891 		err = bpf_map__pin(map, pin_path);
8892 		if (err)
8893 			goto err_unpin_maps;
8894 	}
8895 
8896 	return 0;
8897 
8898 err_unpin_maps:
8899 	while ((map = bpf_object__prev_map(obj, map))) {
8900 		if (!map->pin_path)
8901 			continue;
8902 
8903 		bpf_map__unpin(map, NULL);
8904 	}
8905 
8906 	return libbpf_err(err);
8907 }
8908 
bpf_object__unpin_maps(struct bpf_object * obj,const char * path)8909 int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
8910 {
8911 	struct bpf_map *map;
8912 	int err;
8913 
8914 	if (!obj)
8915 		return libbpf_err(-ENOENT);
8916 
8917 	bpf_object__for_each_map(map, obj) {
8918 		char *pin_path = NULL;
8919 		char buf[PATH_MAX];
8920 
8921 		if (path) {
8922 			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
8923 			if (err)
8924 				return libbpf_err(err);
8925 			sanitize_pin_path(buf);
8926 			pin_path = buf;
8927 		} else if (!map->pin_path) {
8928 			continue;
8929 		}
8930 
8931 		err = bpf_map__unpin(map, pin_path);
8932 		if (err)
8933 			return libbpf_err(err);
8934 	}
8935 
8936 	return 0;
8937 }
8938 
bpf_object__pin_programs(struct bpf_object * obj,const char * path)8939 int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
8940 {
8941 	struct bpf_program *prog;
8942 	char buf[PATH_MAX];
8943 	int err;
8944 
8945 	if (!obj)
8946 		return libbpf_err(-ENOENT);
8947 
8948 	if (!obj->loaded) {
8949 		pr_warn("object not yet loaded; load it first\n");
8950 		return libbpf_err(-ENOENT);
8951 	}
8952 
8953 	bpf_object__for_each_program(prog, obj) {
8954 		err = pathname_concat(buf, sizeof(buf), path, prog->name);
8955 		if (err)
8956 			goto err_unpin_programs;
8957 
8958 		err = bpf_program__pin(prog, buf);
8959 		if (err)
8960 			goto err_unpin_programs;
8961 	}
8962 
8963 	return 0;
8964 
8965 err_unpin_programs:
8966 	while ((prog = bpf_object__prev_program(obj, prog))) {
8967 		if (pathname_concat(buf, sizeof(buf), path, prog->name))
8968 			continue;
8969 
8970 		bpf_program__unpin(prog, buf);
8971 	}
8972 
8973 	return libbpf_err(err);
8974 }
8975 
bpf_object__unpin_programs(struct bpf_object * obj,const char * path)8976 int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
8977 {
8978 	struct bpf_program *prog;
8979 	int err;
8980 
8981 	if (!obj)
8982 		return libbpf_err(-ENOENT);
8983 
8984 	bpf_object__for_each_program(prog, obj) {
8985 		char buf[PATH_MAX];
8986 
8987 		err = pathname_concat(buf, sizeof(buf), path, prog->name);
8988 		if (err)
8989 			return libbpf_err(err);
8990 
8991 		err = bpf_program__unpin(prog, buf);
8992 		if (err)
8993 			return libbpf_err(err);
8994 	}
8995 
8996 	return 0;
8997 }
8998 
bpf_object__pin(struct bpf_object * obj,const char * path)8999 int bpf_object__pin(struct bpf_object *obj, const char *path)
9000 {
9001 	int err;
9002 
9003 	err = bpf_object__pin_maps(obj, path);
9004 	if (err)
9005 		return libbpf_err(err);
9006 
9007 	err = bpf_object__pin_programs(obj, path);
9008 	if (err) {
9009 		bpf_object__unpin_maps(obj, path);
9010 		return libbpf_err(err);
9011 	}
9012 
9013 	return 0;
9014 }
9015 
bpf_object__unpin(struct bpf_object * obj,const char * path)9016 int bpf_object__unpin(struct bpf_object *obj, const char *path)
9017 {
9018 	int err;
9019 
9020 	err = bpf_object__unpin_programs(obj, path);
9021 	if (err)
9022 		return libbpf_err(err);
9023 
9024 	err = bpf_object__unpin_maps(obj, path);
9025 	if (err)
9026 		return libbpf_err(err);
9027 
9028 	return 0;
9029 }
9030 
bpf_map__destroy(struct bpf_map * map)9031 static void bpf_map__destroy(struct bpf_map *map)
9032 {
9033 	if (map->inner_map) {
9034 		bpf_map__destroy(map->inner_map);
9035 		zfree(&map->inner_map);
9036 	}
9037 
9038 	zfree(&map->init_slots);
9039 	map->init_slots_sz = 0;
9040 
9041 	if (map->mmaped && map->mmaped != map->obj->arena_data)
9042 		munmap(map->mmaped, bpf_map_mmap_sz(map));
9043 	map->mmaped = NULL;
9044 
9045 	if (map->st_ops) {
9046 		zfree(&map->st_ops->data);
9047 		zfree(&map->st_ops->progs);
9048 		zfree(&map->st_ops->kern_func_off);
9049 		zfree(&map->st_ops);
9050 	}
9051 
9052 	zfree(&map->name);
9053 	zfree(&map->real_name);
9054 	zfree(&map->pin_path);
9055 
9056 	if (map->fd >= 0)
9057 		zclose(map->fd);
9058 }
9059 
bpf_object__close(struct bpf_object * obj)9060 void bpf_object__close(struct bpf_object *obj)
9061 {
9062 	size_t i;
9063 
9064 	if (IS_ERR_OR_NULL(obj))
9065 		return;
9066 
9067 	usdt_manager_free(obj->usdt_man);
9068 	obj->usdt_man = NULL;
9069 
9070 	bpf_gen__free(obj->gen_loader);
9071 	bpf_object__elf_finish(obj);
9072 	bpf_object_unload(obj);
9073 	btf__free(obj->btf);
9074 	btf__free(obj->btf_vmlinux);
9075 	btf_ext__free(obj->btf_ext);
9076 
9077 	for (i = 0; i < obj->nr_maps; i++)
9078 		bpf_map__destroy(&obj->maps[i]);
9079 
9080 	zfree(&obj->btf_custom_path);
9081 	zfree(&obj->kconfig);
9082 
9083 	for (i = 0; i < obj->nr_extern; i++)
9084 		zfree(&obj->externs[i].essent_name);
9085 
9086 	zfree(&obj->externs);
9087 	obj->nr_extern = 0;
9088 
9089 	zfree(&obj->maps);
9090 	obj->nr_maps = 0;
9091 
9092 	if (obj->programs && obj->nr_programs) {
9093 		for (i = 0; i < obj->nr_programs; i++)
9094 			bpf_program__exit(&obj->programs[i]);
9095 	}
9096 	zfree(&obj->programs);
9097 
9098 	zfree(&obj->feat_cache);
9099 	zfree(&obj->token_path);
9100 	if (obj->token_fd > 0)
9101 		close(obj->token_fd);
9102 
9103 	zfree(&obj->arena_data);
9104 
9105 	free(obj);
9106 }
9107 
bpf_object__name(const struct bpf_object * obj)9108 const char *bpf_object__name(const struct bpf_object *obj)
9109 {
9110 	return obj ? obj->name : libbpf_err_ptr(-EINVAL);
9111 }
9112 
bpf_object__kversion(const struct bpf_object * obj)9113 unsigned int bpf_object__kversion(const struct bpf_object *obj)
9114 {
9115 	return obj ? obj->kern_version : 0;
9116 }
9117 
bpf_object__token_fd(const struct bpf_object * obj)9118 int bpf_object__token_fd(const struct bpf_object *obj)
9119 {
9120 	return obj->token_fd ?: -1;
9121 }
9122 
bpf_object__btf(const struct bpf_object * obj)9123 struct btf *bpf_object__btf(const struct bpf_object *obj)
9124 {
9125 	return obj ? obj->btf : NULL;
9126 }
9127 
bpf_object__btf_fd(const struct bpf_object * obj)9128 int bpf_object__btf_fd(const struct bpf_object *obj)
9129 {
9130 	return obj->btf ? btf__fd(obj->btf) : -1;
9131 }
9132 
bpf_object__set_kversion(struct bpf_object * obj,__u32 kern_version)9133 int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
9134 {
9135 	if (obj->loaded)
9136 		return libbpf_err(-EINVAL);
9137 
9138 	obj->kern_version = kern_version;
9139 
9140 	return 0;
9141 }
9142 
bpf_object__gen_loader(struct bpf_object * obj,struct gen_loader_opts * opts)9143 int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts)
9144 {
9145 	struct bpf_gen *gen;
9146 
9147 	if (!opts)
9148 		return -EFAULT;
9149 	if (!OPTS_VALID(opts, gen_loader_opts))
9150 		return -EINVAL;
9151 	gen = calloc(sizeof(*gen), 1);
9152 	if (!gen)
9153 		return -ENOMEM;
9154 	gen->opts = opts;
9155 	gen->swapped_endian = !is_native_endianness(obj);
9156 	obj->gen_loader = gen;
9157 	return 0;
9158 }
9159 
9160 static struct bpf_program *
__bpf_program__iter(const struct bpf_program * p,const struct bpf_object * obj,bool forward)9161 __bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
9162 		    bool forward)
9163 {
9164 	size_t nr_programs = obj->nr_programs;
9165 	ssize_t idx;
9166 
9167 	if (!nr_programs)
9168 		return NULL;
9169 
9170 	if (!p)
9171 		/* Iter from the beginning */
9172 		return forward ? &obj->programs[0] :
9173 			&obj->programs[nr_programs - 1];
9174 
9175 	if (p->obj != obj) {
9176 		pr_warn("error: program handler doesn't match object\n");
9177 		return errno = EINVAL, NULL;
9178 	}
9179 
9180 	idx = (p - obj->programs) + (forward ? 1 : -1);
9181 	if (idx >= obj->nr_programs || idx < 0)
9182 		return NULL;
9183 	return &obj->programs[idx];
9184 }
9185 
9186 struct bpf_program *
bpf_object__next_program(const struct bpf_object * obj,struct bpf_program * prev)9187 bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev)
9188 {
9189 	struct bpf_program *prog = prev;
9190 
9191 	do {
9192 		prog = __bpf_program__iter(prog, obj, true);
9193 	} while (prog && prog_is_subprog(obj, prog));
9194 
9195 	return prog;
9196 }
9197 
9198 struct bpf_program *
bpf_object__prev_program(const struct bpf_object * obj,struct bpf_program * next)9199 bpf_object__prev_program(const struct bpf_object *obj, struct bpf_program *next)
9200 {
9201 	struct bpf_program *prog = next;
9202 
9203 	do {
9204 		prog = __bpf_program__iter(prog, obj, false);
9205 	} while (prog && prog_is_subprog(obj, prog));
9206 
9207 	return prog;
9208 }
9209 
bpf_program__set_ifindex(struct bpf_program * prog,__u32 ifindex)9210 void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
9211 {
9212 	prog->prog_ifindex = ifindex;
9213 }
9214 
bpf_program__name(const struct bpf_program * prog)9215 const char *bpf_program__name(const struct bpf_program *prog)
9216 {
9217 	return prog->name;
9218 }
9219 
bpf_program__section_name(const struct bpf_program * prog)9220 const char *bpf_program__section_name(const struct bpf_program *prog)
9221 {
9222 	return prog->sec_name;
9223 }
9224 
bpf_program__autoload(const struct bpf_program * prog)9225 bool bpf_program__autoload(const struct bpf_program *prog)
9226 {
9227 	return prog->autoload;
9228 }
9229 
bpf_program__set_autoload(struct bpf_program * prog,bool autoload)9230 int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
9231 {
9232 	if (prog->obj->loaded)
9233 		return libbpf_err(-EINVAL);
9234 
9235 	prog->autoload = autoload;
9236 	return 0;
9237 }
9238 
bpf_program__autoattach(const struct bpf_program * prog)9239 bool bpf_program__autoattach(const struct bpf_program *prog)
9240 {
9241 	return prog->autoattach;
9242 }
9243 
bpf_program__set_autoattach(struct bpf_program * prog,bool autoattach)9244 void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach)
9245 {
9246 	prog->autoattach = autoattach;
9247 }
9248 
bpf_program__insns(const struct bpf_program * prog)9249 const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)
9250 {
9251 	return prog->insns;
9252 }
9253 
bpf_program__insn_cnt(const struct bpf_program * prog)9254 size_t bpf_program__insn_cnt(const struct bpf_program *prog)
9255 {
9256 	return prog->insns_cnt;
9257 }
9258 
bpf_program__set_insns(struct bpf_program * prog,struct bpf_insn * new_insns,size_t new_insn_cnt)9259 int bpf_program__set_insns(struct bpf_program *prog,
9260 			   struct bpf_insn *new_insns, size_t new_insn_cnt)
9261 {
9262 	struct bpf_insn *insns;
9263 
9264 	if (prog->obj->loaded)
9265 		return -EBUSY;
9266 
9267 	insns = libbpf_reallocarray(prog->insns, new_insn_cnt, sizeof(*insns));
9268 	/* NULL is a valid return from reallocarray if the new count is zero */
9269 	if (!insns && new_insn_cnt) {
9270 		pr_warn("prog '%s': failed to realloc prog code\n", prog->name);
9271 		return -ENOMEM;
9272 	}
9273 	memcpy(insns, new_insns, new_insn_cnt * sizeof(*insns));
9274 
9275 	prog->insns = insns;
9276 	prog->insns_cnt = new_insn_cnt;
9277 	return 0;
9278 }
9279 
bpf_program__fd(const struct bpf_program * prog)9280 int bpf_program__fd(const struct bpf_program *prog)
9281 {
9282 	if (!prog)
9283 		return libbpf_err(-EINVAL);
9284 
9285 	if (prog->fd < 0)
9286 		return libbpf_err(-ENOENT);
9287 
9288 	return prog->fd;
9289 }
9290 
9291 __alias(bpf_program__type)
9292 enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
9293 
bpf_program__type(const struct bpf_program * prog)9294 enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
9295 {
9296 	return prog->type;
9297 }
9298 
9299 static size_t custom_sec_def_cnt;
9300 static struct bpf_sec_def *custom_sec_defs;
9301 static struct bpf_sec_def custom_fallback_def;
9302 static bool has_custom_fallback_def;
9303 static int last_custom_sec_def_handler_id;
9304 
bpf_program__set_type(struct bpf_program * prog,enum bpf_prog_type type)9305 int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
9306 {
9307 	if (prog->obj->loaded)
9308 		return libbpf_err(-EBUSY);
9309 
9310 	/* if type is not changed, do nothing */
9311 	if (prog->type == type)
9312 		return 0;
9313 
9314 	prog->type = type;
9315 
9316 	/* If a program type was changed, we need to reset associated SEC()
9317 	 * handler, as it will be invalid now. The only exception is a generic
9318 	 * fallback handler, which by definition is program type-agnostic and
9319 	 * is a catch-all custom handler, optionally set by the application,
9320 	 * so should be able to handle any type of BPF program.
9321 	 */
9322 	if (prog->sec_def != &custom_fallback_def)
9323 		prog->sec_def = NULL;
9324 	return 0;
9325 }
9326 
9327 __alias(bpf_program__expected_attach_type)
9328 enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
9329 
bpf_program__expected_attach_type(const struct bpf_program * prog)9330 enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program *prog)
9331 {
9332 	return prog->expected_attach_type;
9333 }
9334 
bpf_program__set_expected_attach_type(struct bpf_program * prog,enum bpf_attach_type type)9335 int bpf_program__set_expected_attach_type(struct bpf_program *prog,
9336 					   enum bpf_attach_type type)
9337 {
9338 	if (prog->obj->loaded)
9339 		return libbpf_err(-EBUSY);
9340 
9341 	prog->expected_attach_type = type;
9342 	return 0;
9343 }
9344 
bpf_program__flags(const struct bpf_program * prog)9345 __u32 bpf_program__flags(const struct bpf_program *prog)
9346 {
9347 	return prog->prog_flags;
9348 }
9349 
bpf_program__set_flags(struct bpf_program * prog,__u32 flags)9350 int bpf_program__set_flags(struct bpf_program *prog, __u32 flags)
9351 {
9352 	if (prog->obj->loaded)
9353 		return libbpf_err(-EBUSY);
9354 
9355 	prog->prog_flags = flags;
9356 	return 0;
9357 }
9358 
bpf_program__log_level(const struct bpf_program * prog)9359 __u32 bpf_program__log_level(const struct bpf_program *prog)
9360 {
9361 	return prog->log_level;
9362 }
9363 
bpf_program__set_log_level(struct bpf_program * prog,__u32 log_level)9364 int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
9365 {
9366 	if (prog->obj->loaded)
9367 		return libbpf_err(-EBUSY);
9368 
9369 	prog->log_level = log_level;
9370 	return 0;
9371 }
9372 
bpf_program__log_buf(const struct bpf_program * prog,size_t * log_size)9373 const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size)
9374 {
9375 	*log_size = prog->log_size;
9376 	return prog->log_buf;
9377 }
9378 
bpf_program__set_log_buf(struct bpf_program * prog,char * log_buf,size_t log_size)9379 int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size)
9380 {
9381 	if (log_size && !log_buf)
9382 		return -EINVAL;
9383 	if (prog->log_size > UINT_MAX)
9384 		return -EINVAL;
9385 	if (prog->obj->loaded)
9386 		return -EBUSY;
9387 
9388 	prog->log_buf = log_buf;
9389 	prog->log_size = log_size;
9390 	return 0;
9391 }
9392 
9393 #define SEC_DEF(sec_pfx, ptype, atype, flags, ...) {			    \
9394 	.sec = (char *)sec_pfx,						    \
9395 	.prog_type = BPF_PROG_TYPE_##ptype,				    \
9396 	.expected_attach_type = atype,					    \
9397 	.cookie = (long)(flags),					    \
9398 	.prog_prepare_load_fn = libbpf_prepare_prog_load,		    \
9399 	__VA_ARGS__							    \
9400 }
9401 
9402 static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9403 static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9404 static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9405 static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9406 static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9407 static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9408 static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9409 static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9410 static int attach_kprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9411 static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9412 static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9413 static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
9414 
9415 static const struct bpf_sec_def section_defs[] = {
9416 	SEC_DEF("socket",		SOCKET_FILTER, 0, SEC_NONE),
9417 	SEC_DEF("sk_reuseport/migrate",	SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE),
9418 	SEC_DEF("sk_reuseport",		SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE),
9419 	SEC_DEF("kprobe+",		KPROBE,	0, SEC_NONE, attach_kprobe),
9420 	SEC_DEF("uprobe+",		KPROBE,	0, SEC_NONE, attach_uprobe),
9421 	SEC_DEF("uprobe.s+",		KPROBE,	0, SEC_SLEEPABLE, attach_uprobe),
9422 	SEC_DEF("kretprobe+",		KPROBE, 0, SEC_NONE, attach_kprobe),
9423 	SEC_DEF("uretprobe+",		KPROBE, 0, SEC_NONE, attach_uprobe),
9424 	SEC_DEF("uretprobe.s+",		KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
9425 	SEC_DEF("kprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
9426 	SEC_DEF("kretprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
9427 	SEC_DEF("kprobe.session+",	KPROBE,	BPF_TRACE_KPROBE_SESSION, SEC_NONE, attach_kprobe_session),
9428 	SEC_DEF("uprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
9429 	SEC_DEF("uretprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
9430 	SEC_DEF("uprobe.session+",	KPROBE,	BPF_TRACE_UPROBE_SESSION, SEC_NONE, attach_uprobe_multi),
9431 	SEC_DEF("uprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
9432 	SEC_DEF("uretprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
9433 	SEC_DEF("uprobe.session.s+",	KPROBE,	BPF_TRACE_UPROBE_SESSION, SEC_SLEEPABLE, attach_uprobe_multi),
9434 	SEC_DEF("ksyscall+",		KPROBE,	0, SEC_NONE, attach_ksyscall),
9435 	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
9436 	SEC_DEF("usdt+",		KPROBE,	0, SEC_USDT, attach_usdt),
9437 	SEC_DEF("usdt.s+",		KPROBE,	0, SEC_USDT | SEC_SLEEPABLE, attach_usdt),
9438 	SEC_DEF("tc/ingress",		SCHED_CLS, BPF_TCX_INGRESS, SEC_NONE), /* alias for tcx */
9439 	SEC_DEF("tc/egress",		SCHED_CLS, BPF_TCX_EGRESS, SEC_NONE),  /* alias for tcx */
9440 	SEC_DEF("tcx/ingress",		SCHED_CLS, BPF_TCX_INGRESS, SEC_NONE),
9441 	SEC_DEF("tcx/egress",		SCHED_CLS, BPF_TCX_EGRESS, SEC_NONE),
9442 	SEC_DEF("tc",			SCHED_CLS, 0, SEC_NONE), /* deprecated / legacy, use tcx */
9443 	SEC_DEF("classifier",		SCHED_CLS, 0, SEC_NONE), /* deprecated / legacy, use tcx */
9444 	SEC_DEF("action",		SCHED_ACT, 0, SEC_NONE), /* deprecated / legacy, use tcx */
9445 	SEC_DEF("netkit/primary",	SCHED_CLS, BPF_NETKIT_PRIMARY, SEC_NONE),
9446 	SEC_DEF("netkit/peer",		SCHED_CLS, BPF_NETKIT_PEER, SEC_NONE),
9447 	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
9448 	SEC_DEF("tp+",			TRACEPOINT, 0, SEC_NONE, attach_tp),
9449 	SEC_DEF("raw_tracepoint+",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
9450 	SEC_DEF("raw_tp+",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
9451 	SEC_DEF("raw_tracepoint.w+",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
9452 	SEC_DEF("raw_tp.w+",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
9453 	SEC_DEF("tp_btf+",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
9454 	SEC_DEF("fentry+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
9455 	SEC_DEF("fmod_ret+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
9456 	SEC_DEF("fexit+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
9457 	SEC_DEF("fentry.s+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
9458 	SEC_DEF("fmod_ret.s+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
9459 	SEC_DEF("fexit.s+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
9460 	SEC_DEF("freplace+",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
9461 	SEC_DEF("lsm+",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
9462 	SEC_DEF("lsm.s+",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
9463 	SEC_DEF("lsm_cgroup+",		LSM, BPF_LSM_CGROUP, SEC_ATTACH_BTF),
9464 	SEC_DEF("iter+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
9465 	SEC_DEF("iter.s+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
9466 	SEC_DEF("syscall",		SYSCALL, 0, SEC_SLEEPABLE),
9467 	SEC_DEF("xdp.frags/devmap",	XDP, BPF_XDP_DEVMAP, SEC_XDP_FRAGS),
9468 	SEC_DEF("xdp/devmap",		XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
9469 	SEC_DEF("xdp.frags/cpumap",	XDP, BPF_XDP_CPUMAP, SEC_XDP_FRAGS),
9470 	SEC_DEF("xdp/cpumap",		XDP, BPF_XDP_CPUMAP, SEC_ATTACHABLE),
9471 	SEC_DEF("xdp.frags",		XDP, BPF_XDP, SEC_XDP_FRAGS),
9472 	SEC_DEF("xdp",			XDP, BPF_XDP, SEC_ATTACHABLE_OPT),
9473 	SEC_DEF("perf_event",		PERF_EVENT, 0, SEC_NONE),
9474 	SEC_DEF("lwt_in",		LWT_IN, 0, SEC_NONE),
9475 	SEC_DEF("lwt_out",		LWT_OUT, 0, SEC_NONE),
9476 	SEC_DEF("lwt_xmit",		LWT_XMIT, 0, SEC_NONE),
9477 	SEC_DEF("lwt_seg6local",	LWT_SEG6LOCAL, 0, SEC_NONE),
9478 	SEC_DEF("sockops",		SOCK_OPS, BPF_CGROUP_SOCK_OPS, SEC_ATTACHABLE_OPT),
9479 	SEC_DEF("sk_skb/stream_parser",	SK_SKB, BPF_SK_SKB_STREAM_PARSER, SEC_ATTACHABLE_OPT),
9480 	SEC_DEF("sk_skb/stream_verdict",SK_SKB, BPF_SK_SKB_STREAM_VERDICT, SEC_ATTACHABLE_OPT),
9481 	SEC_DEF("sk_skb/verdict",	SK_SKB, BPF_SK_SKB_VERDICT, SEC_ATTACHABLE_OPT),
9482 	SEC_DEF("sk_skb",		SK_SKB, 0, SEC_NONE),
9483 	SEC_DEF("sk_msg",		SK_MSG, BPF_SK_MSG_VERDICT, SEC_ATTACHABLE_OPT),
9484 	SEC_DEF("lirc_mode2",		LIRC_MODE2, BPF_LIRC_MODE2, SEC_ATTACHABLE_OPT),
9485 	SEC_DEF("flow_dissector",	FLOW_DISSECTOR, BPF_FLOW_DISSECTOR, SEC_ATTACHABLE_OPT),
9486 	SEC_DEF("cgroup_skb/ingress",	CGROUP_SKB, BPF_CGROUP_INET_INGRESS, SEC_ATTACHABLE_OPT),
9487 	SEC_DEF("cgroup_skb/egress",	CGROUP_SKB, BPF_CGROUP_INET_EGRESS, SEC_ATTACHABLE_OPT),
9488 	SEC_DEF("cgroup/skb",		CGROUP_SKB, 0, SEC_NONE),
9489 	SEC_DEF("cgroup/sock_create",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE),
9490 	SEC_DEF("cgroup/sock_release",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_RELEASE, SEC_ATTACHABLE),
9491 	SEC_DEF("cgroup/sock",		CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE_OPT),
9492 	SEC_DEF("cgroup/post_bind4",	CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND, SEC_ATTACHABLE),
9493 	SEC_DEF("cgroup/post_bind6",	CGROUP_SOCK, BPF_CGROUP_INET6_POST_BIND, SEC_ATTACHABLE),
9494 	SEC_DEF("cgroup/bind4",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND, SEC_ATTACHABLE),
9495 	SEC_DEF("cgroup/bind6",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_BIND, SEC_ATTACHABLE),
9496 	SEC_DEF("cgroup/connect4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_CONNECT, SEC_ATTACHABLE),
9497 	SEC_DEF("cgroup/connect6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_CONNECT, SEC_ATTACHABLE),
9498 	SEC_DEF("cgroup/connect_unix",	CGROUP_SOCK_ADDR, BPF_CGROUP_UNIX_CONNECT, SEC_ATTACHABLE),
9499 	SEC_DEF("cgroup/sendmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_SENDMSG, SEC_ATTACHABLE),
9500 	SEC_DEF("cgroup/sendmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_SENDMSG, SEC_ATTACHABLE),
9501 	SEC_DEF("cgroup/sendmsg_unix",	CGROUP_SOCK_ADDR, BPF_CGROUP_UNIX_SENDMSG, SEC_ATTACHABLE),
9502 	SEC_DEF("cgroup/recvmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_RECVMSG, SEC_ATTACHABLE),
9503 	SEC_DEF("cgroup/recvmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_RECVMSG, SEC_ATTACHABLE),
9504 	SEC_DEF("cgroup/recvmsg_unix",	CGROUP_SOCK_ADDR, BPF_CGROUP_UNIX_RECVMSG, SEC_ATTACHABLE),
9505 	SEC_DEF("cgroup/getpeername4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETPEERNAME, SEC_ATTACHABLE),
9506 	SEC_DEF("cgroup/getpeername6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETPEERNAME, SEC_ATTACHABLE),
9507 	SEC_DEF("cgroup/getpeername_unix", CGROUP_SOCK_ADDR, BPF_CGROUP_UNIX_GETPEERNAME, SEC_ATTACHABLE),
9508 	SEC_DEF("cgroup/getsockname4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETSOCKNAME, SEC_ATTACHABLE),
9509 	SEC_DEF("cgroup/getsockname6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETSOCKNAME, SEC_ATTACHABLE),
9510 	SEC_DEF("cgroup/getsockname_unix", CGROUP_SOCK_ADDR, BPF_CGROUP_UNIX_GETSOCKNAME, SEC_ATTACHABLE),
9511 	SEC_DEF("cgroup/sysctl",	CGROUP_SYSCTL, BPF_CGROUP_SYSCTL, SEC_ATTACHABLE),
9512 	SEC_DEF("cgroup/getsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT, SEC_ATTACHABLE),
9513 	SEC_DEF("cgroup/setsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT, SEC_ATTACHABLE),
9514 	SEC_DEF("cgroup/dev",		CGROUP_DEVICE, BPF_CGROUP_DEVICE, SEC_ATTACHABLE_OPT),
9515 	SEC_DEF("struct_ops+",		STRUCT_OPS, 0, SEC_NONE),
9516 	SEC_DEF("struct_ops.s+",	STRUCT_OPS, 0, SEC_SLEEPABLE),
9517 	SEC_DEF("sk_lookup",		SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
9518 	SEC_DEF("netfilter",		NETFILTER, BPF_NETFILTER, SEC_NONE),
9519 };
9520 
libbpf_register_prog_handler(const char * sec,enum bpf_prog_type prog_type,enum bpf_attach_type exp_attach_type,const struct libbpf_prog_handler_opts * opts)9521 int libbpf_register_prog_handler(const char *sec,
9522 				 enum bpf_prog_type prog_type,
9523 				 enum bpf_attach_type exp_attach_type,
9524 				 const struct libbpf_prog_handler_opts *opts)
9525 {
9526 	struct bpf_sec_def *sec_def;
9527 
9528 	if (!OPTS_VALID(opts, libbpf_prog_handler_opts))
9529 		return libbpf_err(-EINVAL);
9530 
9531 	if (last_custom_sec_def_handler_id == INT_MAX) /* prevent overflow */
9532 		return libbpf_err(-E2BIG);
9533 
9534 	if (sec) {
9535 		sec_def = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt + 1,
9536 					      sizeof(*sec_def));
9537 		if (!sec_def)
9538 			return libbpf_err(-ENOMEM);
9539 
9540 		custom_sec_defs = sec_def;
9541 		sec_def = &custom_sec_defs[custom_sec_def_cnt];
9542 	} else {
9543 		if (has_custom_fallback_def)
9544 			return libbpf_err(-EBUSY);
9545 
9546 		sec_def = &custom_fallback_def;
9547 	}
9548 
9549 	sec_def->sec = sec ? strdup(sec) : NULL;
9550 	if (sec && !sec_def->sec)
9551 		return libbpf_err(-ENOMEM);
9552 
9553 	sec_def->prog_type = prog_type;
9554 	sec_def->expected_attach_type = exp_attach_type;
9555 	sec_def->cookie = OPTS_GET(opts, cookie, 0);
9556 
9557 	sec_def->prog_setup_fn = OPTS_GET(opts, prog_setup_fn, NULL);
9558 	sec_def->prog_prepare_load_fn = OPTS_GET(opts, prog_prepare_load_fn, NULL);
9559 	sec_def->prog_attach_fn = OPTS_GET(opts, prog_attach_fn, NULL);
9560 
9561 	sec_def->handler_id = ++last_custom_sec_def_handler_id;
9562 
9563 	if (sec)
9564 		custom_sec_def_cnt++;
9565 	else
9566 		has_custom_fallback_def = true;
9567 
9568 	return sec_def->handler_id;
9569 }
9570 
libbpf_unregister_prog_handler(int handler_id)9571 int libbpf_unregister_prog_handler(int handler_id)
9572 {
9573 	struct bpf_sec_def *sec_defs;
9574 	int i;
9575 
9576 	if (handler_id <= 0)
9577 		return libbpf_err(-EINVAL);
9578 
9579 	if (has_custom_fallback_def && custom_fallback_def.handler_id == handler_id) {
9580 		memset(&custom_fallback_def, 0, sizeof(custom_fallback_def));
9581 		has_custom_fallback_def = false;
9582 		return 0;
9583 	}
9584 
9585 	for (i = 0; i < custom_sec_def_cnt; i++) {
9586 		if (custom_sec_defs[i].handler_id == handler_id)
9587 			break;
9588 	}
9589 
9590 	if (i == custom_sec_def_cnt)
9591 		return libbpf_err(-ENOENT);
9592 
9593 	free(custom_sec_defs[i].sec);
9594 	for (i = i + 1; i < custom_sec_def_cnt; i++)
9595 		custom_sec_defs[i - 1] = custom_sec_defs[i];
9596 	custom_sec_def_cnt--;
9597 
9598 	/* try to shrink the array, but it's ok if we couldn't */
9599 	sec_defs = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt, sizeof(*sec_defs));
9600 	/* if new count is zero, reallocarray can return a valid NULL result;
9601 	 * in this case the previous pointer will be freed, so we *have to*
9602 	 * reassign old pointer to the new value (even if it's NULL)
9603 	 */
9604 	if (sec_defs || custom_sec_def_cnt == 0)
9605 		custom_sec_defs = sec_defs;
9606 
9607 	return 0;
9608 }
9609 
sec_def_matches(const struct bpf_sec_def * sec_def,const char * sec_name)9610 static bool sec_def_matches(const struct bpf_sec_def *sec_def, const char *sec_name)
9611 {
9612 	size_t len = strlen(sec_def->sec);
9613 
9614 	/* "type/" always has to have proper SEC("type/extras") form */
9615 	if (sec_def->sec[len - 1] == '/') {
9616 		if (str_has_pfx(sec_name, sec_def->sec))
9617 			return true;
9618 		return false;
9619 	}
9620 
9621 	/* "type+" means it can be either exact SEC("type") or
9622 	 * well-formed SEC("type/extras") with proper '/' separator
9623 	 */
9624 	if (sec_def->sec[len - 1] == '+') {
9625 		len--;
9626 		/* not even a prefix */
9627 		if (strncmp(sec_name, sec_def->sec, len) != 0)
9628 			return false;
9629 		/* exact match or has '/' separator */
9630 		if (sec_name[len] == '\0' || sec_name[len] == '/')
9631 			return true;
9632 		return false;
9633 	}
9634 
9635 	return strcmp(sec_name, sec_def->sec) == 0;
9636 }
9637 
find_sec_def(const char * sec_name)9638 static const struct bpf_sec_def *find_sec_def(const char *sec_name)
9639 {
9640 	const struct bpf_sec_def *sec_def;
9641 	int i, n;
9642 
9643 	n = custom_sec_def_cnt;
9644 	for (i = 0; i < n; i++) {
9645 		sec_def = &custom_sec_defs[i];
9646 		if (sec_def_matches(sec_def, sec_name))
9647 			return sec_def;
9648 	}
9649 
9650 	n = ARRAY_SIZE(section_defs);
9651 	for (i = 0; i < n; i++) {
9652 		sec_def = &section_defs[i];
9653 		if (sec_def_matches(sec_def, sec_name))
9654 			return sec_def;
9655 	}
9656 
9657 	if (has_custom_fallback_def)
9658 		return &custom_fallback_def;
9659 
9660 	return NULL;
9661 }
9662 
9663 #define MAX_TYPE_NAME_SIZE 32
9664 
libbpf_get_type_names(bool attach_type)9665 static char *libbpf_get_type_names(bool attach_type)
9666 {
9667 	int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE;
9668 	char *buf;
9669 
9670 	buf = malloc(len);
9671 	if (!buf)
9672 		return NULL;
9673 
9674 	buf[0] = '\0';
9675 	/* Forge string buf with all available names */
9676 	for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
9677 		const struct bpf_sec_def *sec_def = &section_defs[i];
9678 
9679 		if (attach_type) {
9680 			if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
9681 				continue;
9682 
9683 			if (!(sec_def->cookie & SEC_ATTACHABLE))
9684 				continue;
9685 		}
9686 
9687 		if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) {
9688 			free(buf);
9689 			return NULL;
9690 		}
9691 		strcat(buf, " ");
9692 		strcat(buf, section_defs[i].sec);
9693 	}
9694 
9695 	return buf;
9696 }
9697 
libbpf_prog_type_by_name(const char * name,enum bpf_prog_type * prog_type,enum bpf_attach_type * expected_attach_type)9698 int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
9699 			     enum bpf_attach_type *expected_attach_type)
9700 {
9701 	const struct bpf_sec_def *sec_def;
9702 	char *type_names;
9703 
9704 	if (!name)
9705 		return libbpf_err(-EINVAL);
9706 
9707 	sec_def = find_sec_def(name);
9708 	if (sec_def) {
9709 		*prog_type = sec_def->prog_type;
9710 		*expected_attach_type = sec_def->expected_attach_type;
9711 		return 0;
9712 	}
9713 
9714 	pr_debug("failed to guess program type from ELF section '%s'\n", name);
9715 	type_names = libbpf_get_type_names(false);
9716 	if (type_names != NULL) {
9717 		pr_debug("supported section(type) names are:%s\n", type_names);
9718 		free(type_names);
9719 	}
9720 
9721 	return libbpf_err(-ESRCH);
9722 }
9723 
libbpf_bpf_attach_type_str(enum bpf_attach_type t)9724 const char *libbpf_bpf_attach_type_str(enum bpf_attach_type t)
9725 {
9726 	if (t < 0 || t >= ARRAY_SIZE(attach_type_name))
9727 		return NULL;
9728 
9729 	return attach_type_name[t];
9730 }
9731 
libbpf_bpf_link_type_str(enum bpf_link_type t)9732 const char *libbpf_bpf_link_type_str(enum bpf_link_type t)
9733 {
9734 	if (t < 0 || t >= ARRAY_SIZE(link_type_name))
9735 		return NULL;
9736 
9737 	return link_type_name[t];
9738 }
9739 
libbpf_bpf_map_type_str(enum bpf_map_type t)9740 const char *libbpf_bpf_map_type_str(enum bpf_map_type t)
9741 {
9742 	if (t < 0 || t >= ARRAY_SIZE(map_type_name))
9743 		return NULL;
9744 
9745 	return map_type_name[t];
9746 }
9747 
libbpf_bpf_prog_type_str(enum bpf_prog_type t)9748 const char *libbpf_bpf_prog_type_str(enum bpf_prog_type t)
9749 {
9750 	if (t < 0 || t >= ARRAY_SIZE(prog_type_name))
9751 		return NULL;
9752 
9753 	return prog_type_name[t];
9754 }
9755 
find_struct_ops_map_by_offset(struct bpf_object * obj,int sec_idx,size_t offset)9756 static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
9757 						     int sec_idx,
9758 						     size_t offset)
9759 {
9760 	struct bpf_map *map;
9761 	size_t i;
9762 
9763 	for (i = 0; i < obj->nr_maps; i++) {
9764 		map = &obj->maps[i];
9765 		if (!bpf_map__is_struct_ops(map))
9766 			continue;
9767 		if (map->sec_idx == sec_idx &&
9768 		    map->sec_offset <= offset &&
9769 		    offset - map->sec_offset < map->def.value_size)
9770 			return map;
9771 	}
9772 
9773 	return NULL;
9774 }
9775 
9776 /* Collect the reloc from ELF, populate the st_ops->progs[], and update
9777  * st_ops->data for shadow type.
9778  */
bpf_object__collect_st_ops_relos(struct bpf_object * obj,Elf64_Shdr * shdr,Elf_Data * data)9779 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
9780 					    Elf64_Shdr *shdr, Elf_Data *data)
9781 {
9782 	const struct btf_type *type;
9783 	const struct btf_member *member;
9784 	struct bpf_struct_ops *st_ops;
9785 	struct bpf_program *prog;
9786 	unsigned int shdr_idx;
9787 	const struct btf *btf;
9788 	struct bpf_map *map;
9789 	unsigned int moff, insn_idx;
9790 	const char *name;
9791 	__u32 member_idx;
9792 	Elf64_Sym *sym;
9793 	Elf64_Rel *rel;
9794 	int i, nrels;
9795 
9796 	btf = obj->btf;
9797 	nrels = shdr->sh_size / shdr->sh_entsize;
9798 	for (i = 0; i < nrels; i++) {
9799 		rel = elf_rel_by_idx(data, i);
9800 		if (!rel) {
9801 			pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
9802 			return -LIBBPF_ERRNO__FORMAT;
9803 		}
9804 
9805 		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
9806 		if (!sym) {
9807 			pr_warn("struct_ops reloc: symbol %zx not found\n",
9808 				(size_t)ELF64_R_SYM(rel->r_info));
9809 			return -LIBBPF_ERRNO__FORMAT;
9810 		}
9811 
9812 		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
9813 		map = find_struct_ops_map_by_offset(obj, shdr->sh_info, rel->r_offset);
9814 		if (!map) {
9815 			pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n",
9816 				(size_t)rel->r_offset);
9817 			return -EINVAL;
9818 		}
9819 
9820 		moff = rel->r_offset - map->sec_offset;
9821 		shdr_idx = sym->st_shndx;
9822 		st_ops = map->st_ops;
9823 		pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
9824 			 map->name,
9825 			 (long long)(rel->r_info >> 32),
9826 			 (long long)sym->st_value,
9827 			 shdr_idx, (size_t)rel->r_offset,
9828 			 map->sec_offset, sym->st_name, name);
9829 
9830 		if (shdr_idx >= SHN_LORESERVE) {
9831 			pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n",
9832 				map->name, (size_t)rel->r_offset, shdr_idx);
9833 			return -LIBBPF_ERRNO__RELOC;
9834 		}
9835 		if (sym->st_value % BPF_INSN_SZ) {
9836 			pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
9837 				map->name, (unsigned long long)sym->st_value);
9838 			return -LIBBPF_ERRNO__FORMAT;
9839 		}
9840 		insn_idx = sym->st_value / BPF_INSN_SZ;
9841 
9842 		type = btf__type_by_id(btf, st_ops->type_id);
9843 		member = find_member_by_offset(type, moff * 8);
9844 		if (!member) {
9845 			pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
9846 				map->name, moff);
9847 			return -EINVAL;
9848 		}
9849 		member_idx = member - btf_members(type);
9850 		name = btf__name_by_offset(btf, member->name_off);
9851 
9852 		if (!resolve_func_ptr(btf, member->type, NULL)) {
9853 			pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
9854 				map->name, name);
9855 			return -EINVAL;
9856 		}
9857 
9858 		prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
9859 		if (!prog) {
9860 			pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
9861 				map->name, shdr_idx, name);
9862 			return -EINVAL;
9863 		}
9864 
9865 		/* prevent the use of BPF prog with invalid type */
9866 		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) {
9867 			pr_warn("struct_ops reloc %s: prog %s is not struct_ops BPF program\n",
9868 				map->name, prog->name);
9869 			return -EINVAL;
9870 		}
9871 
9872 		st_ops->progs[member_idx] = prog;
9873 
9874 		/* st_ops->data will be exposed to users, being returned by
9875 		 * bpf_map__initial_value() as a pointer to the shadow
9876 		 * type. All function pointers in the original struct type
9877 		 * should be converted to a pointer to struct bpf_program
9878 		 * in the shadow type.
9879 		 */
9880 		*((struct bpf_program **)(st_ops->data + moff)) = prog;
9881 	}
9882 
9883 	return 0;
9884 }
9885 
9886 #define BTF_TRACE_PREFIX "btf_trace_"
9887 #define BTF_LSM_PREFIX "bpf_lsm_"
9888 #define BTF_ITER_PREFIX "bpf_iter_"
9889 #define BTF_MAX_NAME_SIZE 128
9890 
btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,const char ** prefix,int * kind)9891 void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
9892 				const char **prefix, int *kind)
9893 {
9894 	switch (attach_type) {
9895 	case BPF_TRACE_RAW_TP:
9896 		*prefix = BTF_TRACE_PREFIX;
9897 		*kind = BTF_KIND_TYPEDEF;
9898 		break;
9899 	case BPF_LSM_MAC:
9900 	case BPF_LSM_CGROUP:
9901 		*prefix = BTF_LSM_PREFIX;
9902 		*kind = BTF_KIND_FUNC;
9903 		break;
9904 	case BPF_TRACE_ITER:
9905 		*prefix = BTF_ITER_PREFIX;
9906 		*kind = BTF_KIND_FUNC;
9907 		break;
9908 	default:
9909 		*prefix = "";
9910 		*kind = BTF_KIND_FUNC;
9911 	}
9912 }
9913 
find_btf_by_prefix_kind(const struct btf * btf,const char * prefix,const char * name,__u32 kind)9914 static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
9915 				   const char *name, __u32 kind)
9916 {
9917 	char btf_type_name[BTF_MAX_NAME_SIZE];
9918 	int ret;
9919 
9920 	ret = snprintf(btf_type_name, sizeof(btf_type_name),
9921 		       "%s%s", prefix, name);
9922 	/* snprintf returns the number of characters written excluding the
9923 	 * terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it
9924 	 * indicates truncation.
9925 	 */
9926 	if (ret < 0 || ret >= sizeof(btf_type_name))
9927 		return -ENAMETOOLONG;
9928 	return btf__find_by_name_kind(btf, btf_type_name, kind);
9929 }
9930 
find_attach_btf_id(struct btf * btf,const char * name,enum bpf_attach_type attach_type)9931 static inline int find_attach_btf_id(struct btf *btf, const char *name,
9932 				     enum bpf_attach_type attach_type)
9933 {
9934 	const char *prefix;
9935 	int kind;
9936 
9937 	btf_get_kernel_prefix_kind(attach_type, &prefix, &kind);
9938 	return find_btf_by_prefix_kind(btf, prefix, name, kind);
9939 }
9940 
libbpf_find_vmlinux_btf_id(const char * name,enum bpf_attach_type attach_type)9941 int libbpf_find_vmlinux_btf_id(const char *name,
9942 			       enum bpf_attach_type attach_type)
9943 {
9944 	struct btf *btf;
9945 	int err;
9946 
9947 	btf = btf__load_vmlinux_btf();
9948 	err = libbpf_get_error(btf);
9949 	if (err) {
9950 		pr_warn("vmlinux BTF is not found\n");
9951 		return libbpf_err(err);
9952 	}
9953 
9954 	err = find_attach_btf_id(btf, name, attach_type);
9955 	if (err <= 0)
9956 		pr_warn("%s is not found in vmlinux BTF\n", name);
9957 
9958 	btf__free(btf);
9959 	return libbpf_err(err);
9960 }
9961 
libbpf_find_prog_btf_id(const char * name,__u32 attach_prog_fd)9962 static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
9963 {
9964 	struct bpf_prog_info info;
9965 	__u32 info_len = sizeof(info);
9966 	struct btf *btf;
9967 	int err;
9968 
9969 	memset(&info, 0, info_len);
9970 	err = bpf_prog_get_info_by_fd(attach_prog_fd, &info, &info_len);
9971 	if (err) {
9972 		pr_warn("failed bpf_prog_get_info_by_fd for FD %d: %s\n",
9973 			attach_prog_fd, errstr(err));
9974 		return err;
9975 	}
9976 
9977 	err = -EINVAL;
9978 	if (!info.btf_id) {
9979 		pr_warn("The target program doesn't have BTF\n");
9980 		goto out;
9981 	}
9982 	btf = btf__load_from_kernel_by_id(info.btf_id);
9983 	err = libbpf_get_error(btf);
9984 	if (err) {
9985 		pr_warn("Failed to get BTF %d of the program: %s\n", info.btf_id, errstr(err));
9986 		goto out;
9987 	}
9988 	err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
9989 	btf__free(btf);
9990 	if (err <= 0) {
9991 		pr_warn("%s is not found in prog's BTF\n", name);
9992 		goto out;
9993 	}
9994 out:
9995 	return err;
9996 }
9997 
find_kernel_btf_id(struct bpf_object * obj,const char * attach_name,enum bpf_attach_type attach_type,int * btf_obj_fd,int * btf_type_id)9998 static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
9999 			      enum bpf_attach_type attach_type,
10000 			      int *btf_obj_fd, int *btf_type_id)
10001 {
10002 	int ret, i, mod_len;
10003 	const char *fn_name, *mod_name = NULL;
10004 
10005 	fn_name = strchr(attach_name, ':');
10006 	if (fn_name) {
10007 		mod_name = attach_name;
10008 		mod_len = fn_name - mod_name;
10009 		fn_name++;
10010 	}
10011 
10012 	if (!mod_name || strncmp(mod_name, "vmlinux", mod_len) == 0) {
10013 		ret = find_attach_btf_id(obj->btf_vmlinux,
10014 					 mod_name ? fn_name : attach_name,
10015 					 attach_type);
10016 		if (ret > 0) {
10017 			*btf_obj_fd = 0; /* vmlinux BTF */
10018 			*btf_type_id = ret;
10019 			return 0;
10020 		}
10021 		if (ret != -ENOENT)
10022 			return ret;
10023 	}
10024 
10025 	ret = load_module_btfs(obj);
10026 	if (ret)
10027 		return ret;
10028 
10029 	for (i = 0; i < obj->btf_module_cnt; i++) {
10030 		const struct module_btf *mod = &obj->btf_modules[i];
10031 
10032 		if (mod_name && strncmp(mod->name, mod_name, mod_len) != 0)
10033 			continue;
10034 
10035 		ret = find_attach_btf_id(mod->btf,
10036 					 mod_name ? fn_name : attach_name,
10037 					 attach_type);
10038 		if (ret > 0) {
10039 			*btf_obj_fd = mod->fd;
10040 			*btf_type_id = ret;
10041 			return 0;
10042 		}
10043 		if (ret == -ENOENT)
10044 			continue;
10045 
10046 		return ret;
10047 	}
10048 
10049 	return -ESRCH;
10050 }
10051 
libbpf_find_attach_btf_id(struct bpf_program * prog,const char * attach_name,int * btf_obj_fd,int * btf_type_id)10052 static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
10053 				     int *btf_obj_fd, int *btf_type_id)
10054 {
10055 	enum bpf_attach_type attach_type = prog->expected_attach_type;
10056 	__u32 attach_prog_fd = prog->attach_prog_fd;
10057 	int err = 0;
10058 
10059 	/* BPF program's BTF ID */
10060 	if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) {
10061 		if (!attach_prog_fd) {
10062 			pr_warn("prog '%s': attach program FD is not set\n", prog->name);
10063 			return -EINVAL;
10064 		}
10065 		err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
10066 		if (err < 0) {
10067 			pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %s\n",
10068 				prog->name, attach_prog_fd, attach_name, errstr(err));
10069 			return err;
10070 		}
10071 		*btf_obj_fd = 0;
10072 		*btf_type_id = err;
10073 		return 0;
10074 	}
10075 
10076 	/* kernel/module BTF ID */
10077 	if (prog->obj->gen_loader) {
10078 		bpf_gen__record_attach_target(prog->obj->gen_loader, attach_name, attach_type);
10079 		*btf_obj_fd = 0;
10080 		*btf_type_id = 1;
10081 	} else {
10082 		err = find_kernel_btf_id(prog->obj, attach_name,
10083 					 attach_type, btf_obj_fd,
10084 					 btf_type_id);
10085 	}
10086 	if (err) {
10087 		pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %s\n",
10088 			prog->name, attach_name, errstr(err));
10089 		return err;
10090 	}
10091 	return 0;
10092 }
10093 
libbpf_attach_type_by_name(const char * name,enum bpf_attach_type * attach_type)10094 int libbpf_attach_type_by_name(const char *name,
10095 			       enum bpf_attach_type *attach_type)
10096 {
10097 	char *type_names;
10098 	const struct bpf_sec_def *sec_def;
10099 
10100 	if (!name)
10101 		return libbpf_err(-EINVAL);
10102 
10103 	sec_def = find_sec_def(name);
10104 	if (!sec_def) {
10105 		pr_debug("failed to guess attach type based on ELF section name '%s'\n", name);
10106 		type_names = libbpf_get_type_names(true);
10107 		if (type_names != NULL) {
10108 			pr_debug("attachable section(type) names are:%s\n", type_names);
10109 			free(type_names);
10110 		}
10111 
10112 		return libbpf_err(-EINVAL);
10113 	}
10114 
10115 	if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
10116 		return libbpf_err(-EINVAL);
10117 	if (!(sec_def->cookie & SEC_ATTACHABLE))
10118 		return libbpf_err(-EINVAL);
10119 
10120 	*attach_type = sec_def->expected_attach_type;
10121 	return 0;
10122 }
10123 
bpf_map__fd(const struct bpf_map * map)10124 int bpf_map__fd(const struct bpf_map *map)
10125 {
10126 	if (!map)
10127 		return libbpf_err(-EINVAL);
10128 	if (!map_is_created(map))
10129 		return -1;
10130 	return map->fd;
10131 }
10132 
map_uses_real_name(const struct bpf_map * map)10133 static bool map_uses_real_name(const struct bpf_map *map)
10134 {
10135 	/* Since libbpf started to support custom .data.* and .rodata.* maps,
10136 	 * their user-visible name differs from kernel-visible name. Users see
10137 	 * such map's corresponding ELF section name as a map name.
10138 	 * This check distinguishes .data/.rodata from .data.* and .rodata.*
10139 	 * maps to know which name has to be returned to the user.
10140 	 */
10141 	if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, DATA_SEC) != 0)
10142 		return true;
10143 	if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, RODATA_SEC) != 0)
10144 		return true;
10145 	return false;
10146 }
10147 
bpf_map__name(const struct bpf_map * map)10148 const char *bpf_map__name(const struct bpf_map *map)
10149 {
10150 	if (!map)
10151 		return NULL;
10152 
10153 	if (map_uses_real_name(map))
10154 		return map->real_name;
10155 
10156 	return map->name;
10157 }
10158 
bpf_map__type(const struct bpf_map * map)10159 enum bpf_map_type bpf_map__type(const struct bpf_map *map)
10160 {
10161 	return map->def.type;
10162 }
10163 
bpf_map__set_type(struct bpf_map * map,enum bpf_map_type type)10164 int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
10165 {
10166 	if (map_is_created(map))
10167 		return libbpf_err(-EBUSY);
10168 	map->def.type = type;
10169 	return 0;
10170 }
10171 
bpf_map__map_flags(const struct bpf_map * map)10172 __u32 bpf_map__map_flags(const struct bpf_map *map)
10173 {
10174 	return map->def.map_flags;
10175 }
10176 
bpf_map__set_map_flags(struct bpf_map * map,__u32 flags)10177 int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
10178 {
10179 	if (map_is_created(map))
10180 		return libbpf_err(-EBUSY);
10181 	map->def.map_flags = flags;
10182 	return 0;
10183 }
10184 
bpf_map__map_extra(const struct bpf_map * map)10185 __u64 bpf_map__map_extra(const struct bpf_map *map)
10186 {
10187 	return map->map_extra;
10188 }
10189 
bpf_map__set_map_extra(struct bpf_map * map,__u64 map_extra)10190 int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra)
10191 {
10192 	if (map_is_created(map))
10193 		return libbpf_err(-EBUSY);
10194 	map->map_extra = map_extra;
10195 	return 0;
10196 }
10197 
bpf_map__numa_node(const struct bpf_map * map)10198 __u32 bpf_map__numa_node(const struct bpf_map *map)
10199 {
10200 	return map->numa_node;
10201 }
10202 
bpf_map__set_numa_node(struct bpf_map * map,__u32 numa_node)10203 int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
10204 {
10205 	if (map_is_created(map))
10206 		return libbpf_err(-EBUSY);
10207 	map->numa_node = numa_node;
10208 	return 0;
10209 }
10210 
bpf_map__key_size(const struct bpf_map * map)10211 __u32 bpf_map__key_size(const struct bpf_map *map)
10212 {
10213 	return map->def.key_size;
10214 }
10215 
bpf_map__set_key_size(struct bpf_map * map,__u32 size)10216 int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
10217 {
10218 	if (map_is_created(map))
10219 		return libbpf_err(-EBUSY);
10220 	map->def.key_size = size;
10221 	return 0;
10222 }
10223 
bpf_map__value_size(const struct bpf_map * map)10224 __u32 bpf_map__value_size(const struct bpf_map *map)
10225 {
10226 	return map->def.value_size;
10227 }
10228 
map_btf_datasec_resize(struct bpf_map * map,__u32 size)10229 static int map_btf_datasec_resize(struct bpf_map *map, __u32 size)
10230 {
10231 	struct btf *btf;
10232 	struct btf_type *datasec_type, *var_type;
10233 	struct btf_var_secinfo *var;
10234 	const struct btf_type *array_type;
10235 	const struct btf_array *array;
10236 	int vlen, element_sz, new_array_id;
10237 	__u32 nr_elements;
10238 
10239 	/* check btf existence */
10240 	btf = bpf_object__btf(map->obj);
10241 	if (!btf)
10242 		return -ENOENT;
10243 
10244 	/* verify map is datasec */
10245 	datasec_type = btf_type_by_id(btf, bpf_map__btf_value_type_id(map));
10246 	if (!btf_is_datasec(datasec_type)) {
10247 		pr_warn("map '%s': cannot be resized, map value type is not a datasec\n",
10248 			bpf_map__name(map));
10249 		return -EINVAL;
10250 	}
10251 
10252 	/* verify datasec has at least one var */
10253 	vlen = btf_vlen(datasec_type);
10254 	if (vlen == 0) {
10255 		pr_warn("map '%s': cannot be resized, map value datasec is empty\n",
10256 			bpf_map__name(map));
10257 		return -EINVAL;
10258 	}
10259 
10260 	/* verify last var in the datasec is an array */
10261 	var = &btf_var_secinfos(datasec_type)[vlen - 1];
10262 	var_type = btf_type_by_id(btf, var->type);
10263 	array_type = skip_mods_and_typedefs(btf, var_type->type, NULL);
10264 	if (!btf_is_array(array_type)) {
10265 		pr_warn("map '%s': cannot be resized, last var must be an array\n",
10266 			bpf_map__name(map));
10267 		return -EINVAL;
10268 	}
10269 
10270 	/* verify request size aligns with array */
10271 	array = btf_array(array_type);
10272 	element_sz = btf__resolve_size(btf, array->type);
10273 	if (element_sz <= 0 || (size - var->offset) % element_sz != 0) {
10274 		pr_warn("map '%s': cannot be resized, element size (%d) doesn't align with new total size (%u)\n",
10275 			bpf_map__name(map), element_sz, size);
10276 		return -EINVAL;
10277 	}
10278 
10279 	/* create a new array based on the existing array, but with new length */
10280 	nr_elements = (size - var->offset) / element_sz;
10281 	new_array_id = btf__add_array(btf, array->index_type, array->type, nr_elements);
10282 	if (new_array_id < 0)
10283 		return new_array_id;
10284 
10285 	/* adding a new btf type invalidates existing pointers to btf objects,
10286 	 * so refresh pointers before proceeding
10287 	 */
10288 	datasec_type = btf_type_by_id(btf, map->btf_value_type_id);
10289 	var = &btf_var_secinfos(datasec_type)[vlen - 1];
10290 	var_type = btf_type_by_id(btf, var->type);
10291 
10292 	/* finally update btf info */
10293 	datasec_type->size = size;
10294 	var->size = size - var->offset;
10295 	var_type->type = new_array_id;
10296 
10297 	return 0;
10298 }
10299 
bpf_map__set_value_size(struct bpf_map * map,__u32 size)10300 int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
10301 {
10302 	if (map->obj->loaded || map->reused)
10303 		return libbpf_err(-EBUSY);
10304 
10305 	if (map->mmaped) {
10306 		size_t mmap_old_sz, mmap_new_sz;
10307 		int err;
10308 
10309 		if (map->def.type != BPF_MAP_TYPE_ARRAY)
10310 			return -EOPNOTSUPP;
10311 
10312 		mmap_old_sz = bpf_map_mmap_sz(map);
10313 		mmap_new_sz = array_map_mmap_sz(size, map->def.max_entries);
10314 		err = bpf_map_mmap_resize(map, mmap_old_sz, mmap_new_sz);
10315 		if (err) {
10316 			pr_warn("map '%s': failed to resize memory-mapped region: %s\n",
10317 				bpf_map__name(map), errstr(err));
10318 			return err;
10319 		}
10320 		err = map_btf_datasec_resize(map, size);
10321 		if (err && err != -ENOENT) {
10322 			pr_warn("map '%s': failed to adjust resized BTF, clearing BTF key/value info: %s\n",
10323 				bpf_map__name(map), errstr(err));
10324 			map->btf_value_type_id = 0;
10325 			map->btf_key_type_id = 0;
10326 		}
10327 	}
10328 
10329 	map->def.value_size = size;
10330 	return 0;
10331 }
10332 
bpf_map__btf_key_type_id(const struct bpf_map * map)10333 __u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
10334 {
10335 	return map ? map->btf_key_type_id : 0;
10336 }
10337 
bpf_map__btf_value_type_id(const struct bpf_map * map)10338 __u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
10339 {
10340 	return map ? map->btf_value_type_id : 0;
10341 }
10342 
bpf_map__set_initial_value(struct bpf_map * map,const void * data,size_t size)10343 int bpf_map__set_initial_value(struct bpf_map *map,
10344 			       const void *data, size_t size)
10345 {
10346 	size_t actual_sz;
10347 
10348 	if (map->obj->loaded || map->reused)
10349 		return libbpf_err(-EBUSY);
10350 
10351 	if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG)
10352 		return libbpf_err(-EINVAL);
10353 
10354 	if (map->def.type == BPF_MAP_TYPE_ARENA)
10355 		actual_sz = map->obj->arena_data_sz;
10356 	else
10357 		actual_sz = map->def.value_size;
10358 	if (size != actual_sz)
10359 		return libbpf_err(-EINVAL);
10360 
10361 	memcpy(map->mmaped, data, size);
10362 	return 0;
10363 }
10364 
bpf_map__initial_value(const struct bpf_map * map,size_t * psize)10365 void *bpf_map__initial_value(const struct bpf_map *map, size_t *psize)
10366 {
10367 	if (bpf_map__is_struct_ops(map)) {
10368 		if (psize)
10369 			*psize = map->def.value_size;
10370 		return map->st_ops->data;
10371 	}
10372 
10373 	if (!map->mmaped)
10374 		return NULL;
10375 
10376 	if (map->def.type == BPF_MAP_TYPE_ARENA)
10377 		*psize = map->obj->arena_data_sz;
10378 	else
10379 		*psize = map->def.value_size;
10380 
10381 	return map->mmaped;
10382 }
10383 
bpf_map__is_internal(const struct bpf_map * map)10384 bool bpf_map__is_internal(const struct bpf_map *map)
10385 {
10386 	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
10387 }
10388 
bpf_map__ifindex(const struct bpf_map * map)10389 __u32 bpf_map__ifindex(const struct bpf_map *map)
10390 {
10391 	return map->map_ifindex;
10392 }
10393 
bpf_map__set_ifindex(struct bpf_map * map,__u32 ifindex)10394 int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
10395 {
10396 	if (map_is_created(map))
10397 		return libbpf_err(-EBUSY);
10398 	map->map_ifindex = ifindex;
10399 	return 0;
10400 }
10401 
bpf_map__set_inner_map_fd(struct bpf_map * map,int fd)10402 int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
10403 {
10404 	if (!bpf_map_type__is_map_in_map(map->def.type)) {
10405 		pr_warn("error: unsupported map type\n");
10406 		return libbpf_err(-EINVAL);
10407 	}
10408 	if (map->inner_map_fd != -1) {
10409 		pr_warn("error: inner_map_fd already specified\n");
10410 		return libbpf_err(-EINVAL);
10411 	}
10412 	if (map->inner_map) {
10413 		bpf_map__destroy(map->inner_map);
10414 		zfree(&map->inner_map);
10415 	}
10416 	map->inner_map_fd = fd;
10417 	return 0;
10418 }
10419 
10420 static struct bpf_map *
__bpf_map__iter(const struct bpf_map * m,const struct bpf_object * obj,int i)10421 __bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
10422 {
10423 	ssize_t idx;
10424 	struct bpf_map *s, *e;
10425 
10426 	if (!obj || !obj->maps)
10427 		return errno = EINVAL, NULL;
10428 
10429 	s = obj->maps;
10430 	e = obj->maps + obj->nr_maps;
10431 
10432 	if ((m < s) || (m >= e)) {
10433 		pr_warn("error in %s: map handler doesn't belong to object\n",
10434 			 __func__);
10435 		return errno = EINVAL, NULL;
10436 	}
10437 
10438 	idx = (m - obj->maps) + i;
10439 	if (idx >= obj->nr_maps || idx < 0)
10440 		return NULL;
10441 	return &obj->maps[idx];
10442 }
10443 
10444 struct bpf_map *
bpf_object__next_map(const struct bpf_object * obj,const struct bpf_map * prev)10445 bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)
10446 {
10447 	if (prev == NULL && obj != NULL)
10448 		return obj->maps;
10449 
10450 	return __bpf_map__iter(prev, obj, 1);
10451 }
10452 
10453 struct bpf_map *
bpf_object__prev_map(const struct bpf_object * obj,const struct bpf_map * next)10454 bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *next)
10455 {
10456 	if (next == NULL && obj != NULL) {
10457 		if (!obj->nr_maps)
10458 			return NULL;
10459 		return obj->maps + obj->nr_maps - 1;
10460 	}
10461 
10462 	return __bpf_map__iter(next, obj, -1);
10463 }
10464 
10465 struct bpf_map *
bpf_object__find_map_by_name(const struct bpf_object * obj,const char * name)10466 bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
10467 {
10468 	struct bpf_map *pos;
10469 
10470 	bpf_object__for_each_map(pos, obj) {
10471 		/* if it's a special internal map name (which always starts
10472 		 * with dot) then check if that special name matches the
10473 		 * real map name (ELF section name)
10474 		 */
10475 		if (name[0] == '.') {
10476 			if (pos->real_name && strcmp(pos->real_name, name) == 0)
10477 				return pos;
10478 			continue;
10479 		}
10480 		/* otherwise map name has to be an exact match */
10481 		if (map_uses_real_name(pos)) {
10482 			if (strcmp(pos->real_name, name) == 0)
10483 				return pos;
10484 			continue;
10485 		}
10486 		if (strcmp(pos->name, name) == 0)
10487 			return pos;
10488 	}
10489 	return errno = ENOENT, NULL;
10490 }
10491 
10492 int
bpf_object__find_map_fd_by_name(const struct bpf_object * obj,const char * name)10493 bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
10494 {
10495 	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
10496 }
10497 
validate_map_op(const struct bpf_map * map,size_t key_sz,size_t value_sz,bool check_value_sz)10498 static int validate_map_op(const struct bpf_map *map, size_t key_sz,
10499 			   size_t value_sz, bool check_value_sz)
10500 {
10501 	if (!map_is_created(map)) /* map is not yet created */
10502 		return -ENOENT;
10503 
10504 	if (map->def.key_size != key_sz) {
10505 		pr_warn("map '%s': unexpected key size %zu provided, expected %u\n",
10506 			map->name, key_sz, map->def.key_size);
10507 		return -EINVAL;
10508 	}
10509 
10510 	if (map->fd < 0) {
10511 		pr_warn("map '%s': can't use BPF map without FD (was it created?)\n", map->name);
10512 		return -EINVAL;
10513 	}
10514 
10515 	if (!check_value_sz)
10516 		return 0;
10517 
10518 	switch (map->def.type) {
10519 	case BPF_MAP_TYPE_PERCPU_ARRAY:
10520 	case BPF_MAP_TYPE_PERCPU_HASH:
10521 	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
10522 	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: {
10523 		int num_cpu = libbpf_num_possible_cpus();
10524 		size_t elem_sz = roundup(map->def.value_size, 8);
10525 
10526 		if (value_sz != num_cpu * elem_sz) {
10527 			pr_warn("map '%s': unexpected value size %zu provided for per-CPU map, expected %d * %zu = %zd\n",
10528 				map->name, value_sz, num_cpu, elem_sz, num_cpu * elem_sz);
10529 			return -EINVAL;
10530 		}
10531 		break;
10532 	}
10533 	default:
10534 		if (map->def.value_size != value_sz) {
10535 			pr_warn("map '%s': unexpected value size %zu provided, expected %u\n",
10536 				map->name, value_sz, map->def.value_size);
10537 			return -EINVAL;
10538 		}
10539 		break;
10540 	}
10541 	return 0;
10542 }
10543 
bpf_map__lookup_elem(const struct bpf_map * map,const void * key,size_t key_sz,void * value,size_t value_sz,__u64 flags)10544 int bpf_map__lookup_elem(const struct bpf_map *map,
10545 			 const void *key, size_t key_sz,
10546 			 void *value, size_t value_sz, __u64 flags)
10547 {
10548 	int err;
10549 
10550 	err = validate_map_op(map, key_sz, value_sz, true);
10551 	if (err)
10552 		return libbpf_err(err);
10553 
10554 	return bpf_map_lookup_elem_flags(map->fd, key, value, flags);
10555 }
10556 
bpf_map__update_elem(const struct bpf_map * map,const void * key,size_t key_sz,const void * value,size_t value_sz,__u64 flags)10557 int bpf_map__update_elem(const struct bpf_map *map,
10558 			 const void *key, size_t key_sz,
10559 			 const void *value, size_t value_sz, __u64 flags)
10560 {
10561 	int err;
10562 
10563 	err = validate_map_op(map, key_sz, value_sz, true);
10564 	if (err)
10565 		return libbpf_err(err);
10566 
10567 	return bpf_map_update_elem(map->fd, key, value, flags);
10568 }
10569 
bpf_map__delete_elem(const struct bpf_map * map,const void * key,size_t key_sz,__u64 flags)10570 int bpf_map__delete_elem(const struct bpf_map *map,
10571 			 const void *key, size_t key_sz, __u64 flags)
10572 {
10573 	int err;
10574 
10575 	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
10576 	if (err)
10577 		return libbpf_err(err);
10578 
10579 	return bpf_map_delete_elem_flags(map->fd, key, flags);
10580 }
10581 
bpf_map__lookup_and_delete_elem(const struct bpf_map * map,const void * key,size_t key_sz,void * value,size_t value_sz,__u64 flags)10582 int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
10583 				    const void *key, size_t key_sz,
10584 				    void *value, size_t value_sz, __u64 flags)
10585 {
10586 	int err;
10587 
10588 	err = validate_map_op(map, key_sz, value_sz, true);
10589 	if (err)
10590 		return libbpf_err(err);
10591 
10592 	return bpf_map_lookup_and_delete_elem_flags(map->fd, key, value, flags);
10593 }
10594 
bpf_map__get_next_key(const struct bpf_map * map,const void * cur_key,void * next_key,size_t key_sz)10595 int bpf_map__get_next_key(const struct bpf_map *map,
10596 			  const void *cur_key, void *next_key, size_t key_sz)
10597 {
10598 	int err;
10599 
10600 	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
10601 	if (err)
10602 		return libbpf_err(err);
10603 
10604 	return bpf_map_get_next_key(map->fd, cur_key, next_key);
10605 }
10606 
libbpf_get_error(const void * ptr)10607 long libbpf_get_error(const void *ptr)
10608 {
10609 	if (!IS_ERR_OR_NULL(ptr))
10610 		return 0;
10611 
10612 	if (IS_ERR(ptr))
10613 		errno = -PTR_ERR(ptr);
10614 
10615 	/* If ptr == NULL, then errno should be already set by the failing
10616 	 * API, because libbpf never returns NULL on success and it now always
10617 	 * sets errno on error. So no extra errno handling for ptr == NULL
10618 	 * case.
10619 	 */
10620 	return -errno;
10621 }
10622 
10623 /* Replace link's underlying BPF program with the new one */
bpf_link__update_program(struct bpf_link * link,struct bpf_program * prog)10624 int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
10625 {
10626 	int ret;
10627 	int prog_fd = bpf_program__fd(prog);
10628 
10629 	if (prog_fd < 0) {
10630 		pr_warn("prog '%s': can't use BPF program without FD (was it loaded?)\n",
10631 			prog->name);
10632 		return libbpf_err(-EINVAL);
10633 	}
10634 
10635 	ret = bpf_link_update(bpf_link__fd(link), prog_fd, NULL);
10636 	return libbpf_err_errno(ret);
10637 }
10638 
10639 /* Release "ownership" of underlying BPF resource (typically, BPF program
10640  * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
10641  * link, when destructed through bpf_link__destroy() call won't attempt to
10642  * detach/unregisted that BPF resource. This is useful in situations where,
10643  * say, attached BPF program has to outlive userspace program that attached it
10644  * in the system. Depending on type of BPF program, though, there might be
10645  * additional steps (like pinning BPF program in BPF FS) necessary to ensure
10646  * exit of userspace program doesn't trigger automatic detachment and clean up
10647  * inside the kernel.
10648  */
bpf_link__disconnect(struct bpf_link * link)10649 void bpf_link__disconnect(struct bpf_link *link)
10650 {
10651 	link->disconnected = true;
10652 }
10653 
bpf_link__destroy(struct bpf_link * link)10654 int bpf_link__destroy(struct bpf_link *link)
10655 {
10656 	int err = 0;
10657 
10658 	if (IS_ERR_OR_NULL(link))
10659 		return 0;
10660 
10661 	if (!link->disconnected && link->detach)
10662 		err = link->detach(link);
10663 	if (link->pin_path)
10664 		free(link->pin_path);
10665 	if (link->dealloc)
10666 		link->dealloc(link);
10667 	else
10668 		free(link);
10669 
10670 	return libbpf_err(err);
10671 }
10672 
bpf_link__fd(const struct bpf_link * link)10673 int bpf_link__fd(const struct bpf_link *link)
10674 {
10675 	return link->fd;
10676 }
10677 
bpf_link__pin_path(const struct bpf_link * link)10678 const char *bpf_link__pin_path(const struct bpf_link *link)
10679 {
10680 	return link->pin_path;
10681 }
10682 
bpf_link__detach_fd(struct bpf_link * link)10683 static int bpf_link__detach_fd(struct bpf_link *link)
10684 {
10685 	return libbpf_err_errno(close(link->fd));
10686 }
10687 
bpf_link__open(const char * path)10688 struct bpf_link *bpf_link__open(const char *path)
10689 {
10690 	struct bpf_link *link;
10691 	int fd;
10692 
10693 	fd = bpf_obj_get(path);
10694 	if (fd < 0) {
10695 		fd = -errno;
10696 		pr_warn("failed to open link at %s: %d\n", path, fd);
10697 		return libbpf_err_ptr(fd);
10698 	}
10699 
10700 	link = calloc(1, sizeof(*link));
10701 	if (!link) {
10702 		close(fd);
10703 		return libbpf_err_ptr(-ENOMEM);
10704 	}
10705 	link->detach = &bpf_link__detach_fd;
10706 	link->fd = fd;
10707 
10708 	link->pin_path = strdup(path);
10709 	if (!link->pin_path) {
10710 		bpf_link__destroy(link);
10711 		return libbpf_err_ptr(-ENOMEM);
10712 	}
10713 
10714 	return link;
10715 }
10716 
bpf_link__detach(struct bpf_link * link)10717 int bpf_link__detach(struct bpf_link *link)
10718 {
10719 	return bpf_link_detach(link->fd) ? -errno : 0;
10720 }
10721 
bpf_link__pin(struct bpf_link * link,const char * path)10722 int bpf_link__pin(struct bpf_link *link, const char *path)
10723 {
10724 	int err;
10725 
10726 	if (link->pin_path)
10727 		return libbpf_err(-EBUSY);
10728 	err = make_parent_dir(path);
10729 	if (err)
10730 		return libbpf_err(err);
10731 	err = check_path(path);
10732 	if (err)
10733 		return libbpf_err(err);
10734 
10735 	link->pin_path = strdup(path);
10736 	if (!link->pin_path)
10737 		return libbpf_err(-ENOMEM);
10738 
10739 	if (bpf_obj_pin(link->fd, link->pin_path)) {
10740 		err = -errno;
10741 		zfree(&link->pin_path);
10742 		return libbpf_err(err);
10743 	}
10744 
10745 	pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
10746 	return 0;
10747 }
10748 
bpf_link__unpin(struct bpf_link * link)10749 int bpf_link__unpin(struct bpf_link *link)
10750 {
10751 	int err;
10752 
10753 	if (!link->pin_path)
10754 		return libbpf_err(-EINVAL);
10755 
10756 	err = unlink(link->pin_path);
10757 	if (err != 0)
10758 		return -errno;
10759 
10760 	pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
10761 	zfree(&link->pin_path);
10762 	return 0;
10763 }
10764 
10765 struct bpf_link_perf {
10766 	struct bpf_link link;
10767 	int perf_event_fd;
10768 	/* legacy kprobe support: keep track of probe identifier and type */
10769 	char *legacy_probe_name;
10770 	bool legacy_is_kprobe;
10771 	bool legacy_is_retprobe;
10772 };
10773 
10774 static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe);
10775 static int remove_uprobe_event_legacy(const char *probe_name, bool retprobe);
10776 
bpf_link_perf_detach(struct bpf_link * link)10777 static int bpf_link_perf_detach(struct bpf_link *link)
10778 {
10779 	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
10780 	int err = 0;
10781 
10782 	if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
10783 		err = -errno;
10784 
10785 	if (perf_link->perf_event_fd != link->fd)
10786 		close(perf_link->perf_event_fd);
10787 	close(link->fd);
10788 
10789 	/* legacy uprobe/kprobe needs to be removed after perf event fd closure */
10790 	if (perf_link->legacy_probe_name) {
10791 		if (perf_link->legacy_is_kprobe) {
10792 			err = remove_kprobe_event_legacy(perf_link->legacy_probe_name,
10793 							 perf_link->legacy_is_retprobe);
10794 		} else {
10795 			err = remove_uprobe_event_legacy(perf_link->legacy_probe_name,
10796 							 perf_link->legacy_is_retprobe);
10797 		}
10798 	}
10799 
10800 	return err;
10801 }
10802 
bpf_link_perf_dealloc(struct bpf_link * link)10803 static void bpf_link_perf_dealloc(struct bpf_link *link)
10804 {
10805 	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
10806 
10807 	free(perf_link->legacy_probe_name);
10808 	free(perf_link);
10809 }
10810 
bpf_program__attach_perf_event_opts(const struct bpf_program * prog,int pfd,const struct bpf_perf_event_opts * opts)10811 struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
10812 						     const struct bpf_perf_event_opts *opts)
10813 {
10814 	struct bpf_link_perf *link;
10815 	int prog_fd, link_fd = -1, err;
10816 	bool force_ioctl_attach;
10817 
10818 	if (!OPTS_VALID(opts, bpf_perf_event_opts))
10819 		return libbpf_err_ptr(-EINVAL);
10820 
10821 	if (pfd < 0) {
10822 		pr_warn("prog '%s': invalid perf event FD %d\n",
10823 			prog->name, pfd);
10824 		return libbpf_err_ptr(-EINVAL);
10825 	}
10826 	prog_fd = bpf_program__fd(prog);
10827 	if (prog_fd < 0) {
10828 		pr_warn("prog '%s': can't attach BPF program without FD (was it loaded?)\n",
10829 			prog->name);
10830 		return libbpf_err_ptr(-EINVAL);
10831 	}
10832 
10833 	link = calloc(1, sizeof(*link));
10834 	if (!link)
10835 		return libbpf_err_ptr(-ENOMEM);
10836 	link->link.detach = &bpf_link_perf_detach;
10837 	link->link.dealloc = &bpf_link_perf_dealloc;
10838 	link->perf_event_fd = pfd;
10839 
10840 	force_ioctl_attach = OPTS_GET(opts, force_ioctl_attach, false);
10841 	if (kernel_supports(prog->obj, FEAT_PERF_LINK) && !force_ioctl_attach) {
10842 		DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
10843 			.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
10844 
10845 		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
10846 		if (link_fd < 0) {
10847 			err = -errno;
10848 			pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %s\n",
10849 				prog->name, pfd, errstr(err));
10850 			goto err_out;
10851 		}
10852 		link->link.fd = link_fd;
10853 	} else {
10854 		if (OPTS_GET(opts, bpf_cookie, 0)) {
10855 			pr_warn("prog '%s': user context value is not supported\n", prog->name);
10856 			err = -EOPNOTSUPP;
10857 			goto err_out;
10858 		}
10859 
10860 		if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
10861 			err = -errno;
10862 			pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
10863 				prog->name, pfd, errstr(err));
10864 			if (err == -EPROTO)
10865 				pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
10866 					prog->name, pfd);
10867 			goto err_out;
10868 		}
10869 		link->link.fd = pfd;
10870 	}
10871 	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
10872 		err = -errno;
10873 		pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n",
10874 			prog->name, pfd, errstr(err));
10875 		goto err_out;
10876 	}
10877 
10878 	return &link->link;
10879 err_out:
10880 	if (link_fd >= 0)
10881 		close(link_fd);
10882 	free(link);
10883 	return libbpf_err_ptr(err);
10884 }
10885 
bpf_program__attach_perf_event(const struct bpf_program * prog,int pfd)10886 struct bpf_link *bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd)
10887 {
10888 	return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
10889 }
10890 
10891 /*
10892  * this function is expected to parse integer in the range of [0, 2^31-1] from
10893  * given file using scanf format string fmt. If actual parsed value is
10894  * negative, the result might be indistinguishable from error
10895  */
parse_uint_from_file(const char * file,const char * fmt)10896 static int parse_uint_from_file(const char *file, const char *fmt)
10897 {
10898 	int err, ret;
10899 	FILE *f;
10900 
10901 	f = fopen(file, "re");
10902 	if (!f) {
10903 		err = -errno;
10904 		pr_debug("failed to open '%s': %s\n", file, errstr(err));
10905 		return err;
10906 	}
10907 	err = fscanf(f, fmt, &ret);
10908 	if (err != 1) {
10909 		err = err == EOF ? -EIO : -errno;
10910 		pr_debug("failed to parse '%s': %s\n", file, errstr(err));
10911 		fclose(f);
10912 		return err;
10913 	}
10914 	fclose(f);
10915 	return ret;
10916 }
10917 
determine_kprobe_perf_type(void)10918 static int determine_kprobe_perf_type(void)
10919 {
10920 	const char *file = "/sys/bus/event_source/devices/kprobe/type";
10921 
10922 	return parse_uint_from_file(file, "%d\n");
10923 }
10924 
determine_uprobe_perf_type(void)10925 static int determine_uprobe_perf_type(void)
10926 {
10927 	const char *file = "/sys/bus/event_source/devices/uprobe/type";
10928 
10929 	return parse_uint_from_file(file, "%d\n");
10930 }
10931 
determine_kprobe_retprobe_bit(void)10932 static int determine_kprobe_retprobe_bit(void)
10933 {
10934 	const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
10935 
10936 	return parse_uint_from_file(file, "config:%d\n");
10937 }
10938 
determine_uprobe_retprobe_bit(void)10939 static int determine_uprobe_retprobe_bit(void)
10940 {
10941 	const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
10942 
10943 	return parse_uint_from_file(file, "config:%d\n");
10944 }
10945 
10946 #define PERF_UPROBE_REF_CTR_OFFSET_BITS 32
10947 #define PERF_UPROBE_REF_CTR_OFFSET_SHIFT 32
10948 
perf_event_open_probe(bool uprobe,bool retprobe,const char * name,uint64_t offset,int pid,size_t ref_ctr_off)10949 static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
10950 				 uint64_t offset, int pid, size_t ref_ctr_off)
10951 {
10952 	const size_t attr_sz = sizeof(struct perf_event_attr);
10953 	struct perf_event_attr attr;
10954 	int type, pfd;
10955 
10956 	if ((__u64)ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
10957 		return -EINVAL;
10958 
10959 	memset(&attr, 0, attr_sz);
10960 
10961 	type = uprobe ? determine_uprobe_perf_type()
10962 		      : determine_kprobe_perf_type();
10963 	if (type < 0) {
10964 		pr_warn("failed to determine %s perf type: %s\n",
10965 			uprobe ? "uprobe" : "kprobe",
10966 			errstr(type));
10967 		return type;
10968 	}
10969 	if (retprobe) {
10970 		int bit = uprobe ? determine_uprobe_retprobe_bit()
10971 				 : determine_kprobe_retprobe_bit();
10972 
10973 		if (bit < 0) {
10974 			pr_warn("failed to determine %s retprobe bit: %s\n",
10975 				uprobe ? "uprobe" : "kprobe",
10976 				errstr(bit));
10977 			return bit;
10978 		}
10979 		attr.config |= 1 << bit;
10980 	}
10981 	attr.size = attr_sz;
10982 	attr.type = type;
10983 	attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
10984 	attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
10985 	attr.config2 = offset;		 /* kprobe_addr or probe_offset */
10986 
10987 	/* pid filter is meaningful only for uprobes */
10988 	pfd = syscall(__NR_perf_event_open, &attr,
10989 		      pid < 0 ? -1 : pid /* pid */,
10990 		      pid == -1 ? 0 : -1 /* cpu */,
10991 		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
10992 	return pfd >= 0 ? pfd : -errno;
10993 }
10994 
append_to_file(const char * file,const char * fmt,...)10995 static int append_to_file(const char *file, const char *fmt, ...)
10996 {
10997 	int fd, n, err = 0;
10998 	va_list ap;
10999 	char buf[1024];
11000 
11001 	va_start(ap, fmt);
11002 	n = vsnprintf(buf, sizeof(buf), fmt, ap);
11003 	va_end(ap);
11004 
11005 	if (n < 0 || n >= sizeof(buf))
11006 		return -EINVAL;
11007 
11008 	fd = open(file, O_WRONLY | O_APPEND | O_CLOEXEC, 0);
11009 	if (fd < 0)
11010 		return -errno;
11011 
11012 	if (write(fd, buf, n) < 0)
11013 		err = -errno;
11014 
11015 	close(fd);
11016 	return err;
11017 }
11018 
11019 #define DEBUGFS "/sys/kernel/debug/tracing"
11020 #define TRACEFS "/sys/kernel/tracing"
11021 
use_debugfs(void)11022 static bool use_debugfs(void)
11023 {
11024 	static int has_debugfs = -1;
11025 
11026 	if (has_debugfs < 0)
11027 		has_debugfs = faccessat(AT_FDCWD, DEBUGFS, F_OK, AT_EACCESS) == 0;
11028 
11029 	return has_debugfs == 1;
11030 }
11031 
tracefs_path(void)11032 static const char *tracefs_path(void)
11033 {
11034 	return use_debugfs() ? DEBUGFS : TRACEFS;
11035 }
11036 
tracefs_kprobe_events(void)11037 static const char *tracefs_kprobe_events(void)
11038 {
11039 	return use_debugfs() ? DEBUGFS"/kprobe_events" : TRACEFS"/kprobe_events";
11040 }
11041 
tracefs_uprobe_events(void)11042 static const char *tracefs_uprobe_events(void)
11043 {
11044 	return use_debugfs() ? DEBUGFS"/uprobe_events" : TRACEFS"/uprobe_events";
11045 }
11046 
tracefs_available_filter_functions(void)11047 static const char *tracefs_available_filter_functions(void)
11048 {
11049 	return use_debugfs() ? DEBUGFS"/available_filter_functions"
11050 			     : TRACEFS"/available_filter_functions";
11051 }
11052 
tracefs_available_filter_functions_addrs(void)11053 static const char *tracefs_available_filter_functions_addrs(void)
11054 {
11055 	return use_debugfs() ? DEBUGFS"/available_filter_functions_addrs"
11056 			     : TRACEFS"/available_filter_functions_addrs";
11057 }
11058 
gen_kprobe_legacy_event_name(char * buf,size_t buf_sz,const char * kfunc_name,size_t offset)11059 static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
11060 					 const char *kfunc_name, size_t offset)
11061 {
11062 	static int index = 0;
11063 	int i;
11064 
11065 	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset,
11066 		 __sync_fetch_and_add(&index, 1));
11067 
11068 	/* sanitize binary_path in the probe name */
11069 	for (i = 0; buf[i]; i++) {
11070 		if (!isalnum(buf[i]))
11071 			buf[i] = '_';
11072 	}
11073 }
11074 
add_kprobe_event_legacy(const char * probe_name,bool retprobe,const char * kfunc_name,size_t offset)11075 static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
11076 				   const char *kfunc_name, size_t offset)
11077 {
11078 	return append_to_file(tracefs_kprobe_events(), "%c:%s/%s %s+0x%zx",
11079 			      retprobe ? 'r' : 'p',
11080 			      retprobe ? "kretprobes" : "kprobes",
11081 			      probe_name, kfunc_name, offset);
11082 }
11083 
remove_kprobe_event_legacy(const char * probe_name,bool retprobe)11084 static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe)
11085 {
11086 	return append_to_file(tracefs_kprobe_events(), "-:%s/%s",
11087 			      retprobe ? "kretprobes" : "kprobes", probe_name);
11088 }
11089 
determine_kprobe_perf_type_legacy(const char * probe_name,bool retprobe)11090 static int determine_kprobe_perf_type_legacy(const char *probe_name, bool retprobe)
11091 {
11092 	char file[256];
11093 
11094 	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
11095 		 tracefs_path(), retprobe ? "kretprobes" : "kprobes", probe_name);
11096 
11097 	return parse_uint_from_file(file, "%d\n");
11098 }
11099 
perf_event_kprobe_open_legacy(const char * probe_name,bool retprobe,const char * kfunc_name,size_t offset,int pid)11100 static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
11101 					 const char *kfunc_name, size_t offset, int pid)
11102 {
11103 	const size_t attr_sz = sizeof(struct perf_event_attr);
11104 	struct perf_event_attr attr;
11105 	int type, pfd, err;
11106 
11107 	err = add_kprobe_event_legacy(probe_name, retprobe, kfunc_name, offset);
11108 	if (err < 0) {
11109 		pr_warn("failed to add legacy kprobe event for '%s+0x%zx': %s\n",
11110 			kfunc_name, offset,
11111 			errstr(err));
11112 		return err;
11113 	}
11114 	type = determine_kprobe_perf_type_legacy(probe_name, retprobe);
11115 	if (type < 0) {
11116 		err = type;
11117 		pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n",
11118 			kfunc_name, offset,
11119 			errstr(err));
11120 		goto err_clean_legacy;
11121 	}
11122 
11123 	memset(&attr, 0, attr_sz);
11124 	attr.size = attr_sz;
11125 	attr.config = type;
11126 	attr.type = PERF_TYPE_TRACEPOINT;
11127 
11128 	pfd = syscall(__NR_perf_event_open, &attr,
11129 		      pid < 0 ? -1 : pid, /* pid */
11130 		      pid == -1 ? 0 : -1, /* cpu */
11131 		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
11132 	if (pfd < 0) {
11133 		err = -errno;
11134 		pr_warn("legacy kprobe perf_event_open() failed: %s\n",
11135 			errstr(err));
11136 		goto err_clean_legacy;
11137 	}
11138 	return pfd;
11139 
11140 err_clean_legacy:
11141 	/* Clear the newly added legacy kprobe_event */
11142 	remove_kprobe_event_legacy(probe_name, retprobe);
11143 	return err;
11144 }
11145 
arch_specific_syscall_pfx(void)11146 static const char *arch_specific_syscall_pfx(void)
11147 {
11148 #if defined(__x86_64__)
11149 	return "x64";
11150 #elif defined(__i386__)
11151 	return "ia32";
11152 #elif defined(__s390x__)
11153 	return "s390x";
11154 #elif defined(__s390__)
11155 	return "s390";
11156 #elif defined(__arm__)
11157 	return "arm";
11158 #elif defined(__aarch64__)
11159 	return "arm64";
11160 #elif defined(__mips__)
11161 	return "mips";
11162 #elif defined(__riscv)
11163 	return "riscv";
11164 #elif defined(__powerpc__)
11165 	return "powerpc";
11166 #elif defined(__powerpc64__)
11167 	return "powerpc64";
11168 #else
11169 	return NULL;
11170 #endif
11171 }
11172 
probe_kern_syscall_wrapper(int token_fd)11173 int probe_kern_syscall_wrapper(int token_fd)
11174 {
11175 	char syscall_name[64];
11176 	const char *ksys_pfx;
11177 
11178 	ksys_pfx = arch_specific_syscall_pfx();
11179 	if (!ksys_pfx)
11180 		return 0;
11181 
11182 	snprintf(syscall_name, sizeof(syscall_name), "__%s_sys_bpf", ksys_pfx);
11183 
11184 	if (determine_kprobe_perf_type() >= 0) {
11185 		int pfd;
11186 
11187 		pfd = perf_event_open_probe(false, false, syscall_name, 0, getpid(), 0);
11188 		if (pfd >= 0)
11189 			close(pfd);
11190 
11191 		return pfd >= 0 ? 1 : 0;
11192 	} else { /* legacy mode */
11193 		char probe_name[128];
11194 
11195 		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), syscall_name, 0);
11196 		if (add_kprobe_event_legacy(probe_name, false, syscall_name, 0) < 0)
11197 			return 0;
11198 
11199 		(void)remove_kprobe_event_legacy(probe_name, false);
11200 		return 1;
11201 	}
11202 }
11203 
11204 struct bpf_link *
bpf_program__attach_kprobe_opts(const struct bpf_program * prog,const char * func_name,const struct bpf_kprobe_opts * opts)11205 bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
11206 				const char *func_name,
11207 				const struct bpf_kprobe_opts *opts)
11208 {
11209 	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
11210 	enum probe_attach_mode attach_mode;
11211 	char *legacy_probe = NULL;
11212 	struct bpf_link *link;
11213 	size_t offset;
11214 	bool retprobe, legacy;
11215 	int pfd, err;
11216 
11217 	if (!OPTS_VALID(opts, bpf_kprobe_opts))
11218 		return libbpf_err_ptr(-EINVAL);
11219 
11220 	attach_mode = OPTS_GET(opts, attach_mode, PROBE_ATTACH_MODE_DEFAULT);
11221 	retprobe = OPTS_GET(opts, retprobe, false);
11222 	offset = OPTS_GET(opts, offset, 0);
11223 	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
11224 
11225 	legacy = determine_kprobe_perf_type() < 0;
11226 	switch (attach_mode) {
11227 	case PROBE_ATTACH_MODE_LEGACY:
11228 		legacy = true;
11229 		pe_opts.force_ioctl_attach = true;
11230 		break;
11231 	case PROBE_ATTACH_MODE_PERF:
11232 		if (legacy)
11233 			return libbpf_err_ptr(-ENOTSUP);
11234 		pe_opts.force_ioctl_attach = true;
11235 		break;
11236 	case PROBE_ATTACH_MODE_LINK:
11237 		if (legacy || !kernel_supports(prog->obj, FEAT_PERF_LINK))
11238 			return libbpf_err_ptr(-ENOTSUP);
11239 		break;
11240 	case PROBE_ATTACH_MODE_DEFAULT:
11241 		break;
11242 	default:
11243 		return libbpf_err_ptr(-EINVAL);
11244 	}
11245 
11246 	if (!legacy) {
11247 		pfd = perf_event_open_probe(false /* uprobe */, retprobe,
11248 					    func_name, offset,
11249 					    -1 /* pid */, 0 /* ref_ctr_off */);
11250 	} else {
11251 		char probe_name[256];
11252 
11253 		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name),
11254 					     func_name, offset);
11255 
11256 		legacy_probe = strdup(probe_name);
11257 		if (!legacy_probe)
11258 			return libbpf_err_ptr(-ENOMEM);
11259 
11260 		pfd = perf_event_kprobe_open_legacy(legacy_probe, retprobe, func_name,
11261 						    offset, -1 /* pid */);
11262 	}
11263 	if (pfd < 0) {
11264 		err = -errno;
11265 		pr_warn("prog '%s': failed to create %s '%s+0x%zx' perf event: %s\n",
11266 			prog->name, retprobe ? "kretprobe" : "kprobe",
11267 			func_name, offset,
11268 			errstr(err));
11269 		goto err_out;
11270 	}
11271 	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
11272 	err = libbpf_get_error(link);
11273 	if (err) {
11274 		close(pfd);
11275 		pr_warn("prog '%s': failed to attach to %s '%s+0x%zx': %s\n",
11276 			prog->name, retprobe ? "kretprobe" : "kprobe",
11277 			func_name, offset,
11278 			errstr(err));
11279 		goto err_clean_legacy;
11280 	}
11281 	if (legacy) {
11282 		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
11283 
11284 		perf_link->legacy_probe_name = legacy_probe;
11285 		perf_link->legacy_is_kprobe = true;
11286 		perf_link->legacy_is_retprobe = retprobe;
11287 	}
11288 
11289 	return link;
11290 
11291 err_clean_legacy:
11292 	if (legacy)
11293 		remove_kprobe_event_legacy(legacy_probe, retprobe);
11294 err_out:
11295 	free(legacy_probe);
11296 	return libbpf_err_ptr(err);
11297 }
11298 
bpf_program__attach_kprobe(const struct bpf_program * prog,bool retprobe,const char * func_name)11299 struct bpf_link *bpf_program__attach_kprobe(const struct bpf_program *prog,
11300 					    bool retprobe,
11301 					    const char *func_name)
11302 {
11303 	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
11304 		.retprobe = retprobe,
11305 	);
11306 
11307 	return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
11308 }
11309 
bpf_program__attach_ksyscall(const struct bpf_program * prog,const char * syscall_name,const struct bpf_ksyscall_opts * opts)11310 struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
11311 					      const char *syscall_name,
11312 					      const struct bpf_ksyscall_opts *opts)
11313 {
11314 	LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
11315 	char func_name[128];
11316 
11317 	if (!OPTS_VALID(opts, bpf_ksyscall_opts))
11318 		return libbpf_err_ptr(-EINVAL);
11319 
11320 	if (kernel_supports(prog->obj, FEAT_SYSCALL_WRAPPER)) {
11321 		/* arch_specific_syscall_pfx() should never return NULL here
11322 		 * because it is guarded by kernel_supports(). However, since
11323 		 * compiler does not know that we have an explicit conditional
11324 		 * as well.
11325 		 */
11326 		snprintf(func_name, sizeof(func_name), "__%s_sys_%s",
11327 			 arch_specific_syscall_pfx() ? : "", syscall_name);
11328 	} else {
11329 		snprintf(func_name, sizeof(func_name), "__se_sys_%s", syscall_name);
11330 	}
11331 
11332 	kprobe_opts.retprobe = OPTS_GET(opts, retprobe, false);
11333 	kprobe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
11334 
11335 	return bpf_program__attach_kprobe_opts(prog, func_name, &kprobe_opts);
11336 }
11337 
11338 /* Adapted from perf/util/string.c */
glob_match(const char * str,const char * pat)11339 bool glob_match(const char *str, const char *pat)
11340 {
11341 	while (*str && *pat && *pat != '*') {
11342 		if (*pat == '?') {      /* Matches any single character */
11343 			str++;
11344 			pat++;
11345 			continue;
11346 		}
11347 		if (*str != *pat)
11348 			return false;
11349 		str++;
11350 		pat++;
11351 	}
11352 	/* Check wild card */
11353 	if (*pat == '*') {
11354 		while (*pat == '*')
11355 			pat++;
11356 		if (!*pat) /* Tail wild card matches all */
11357 			return true;
11358 		while (*str)
11359 			if (glob_match(str++, pat))
11360 				return true;
11361 	}
11362 	return !*str && !*pat;
11363 }
11364 
11365 struct kprobe_multi_resolve {
11366 	const char *pattern;
11367 	unsigned long *addrs;
11368 	size_t cap;
11369 	size_t cnt;
11370 };
11371 
11372 struct avail_kallsyms_data {
11373 	char **syms;
11374 	size_t cnt;
11375 	struct kprobe_multi_resolve *res;
11376 };
11377 
avail_func_cmp(const void * a,const void * b)11378 static int avail_func_cmp(const void *a, const void *b)
11379 {
11380 	return strcmp(*(const char **)a, *(const char **)b);
11381 }
11382 
avail_kallsyms_cb(unsigned long long sym_addr,char sym_type,const char * sym_name,void * ctx)11383 static int avail_kallsyms_cb(unsigned long long sym_addr, char sym_type,
11384 			     const char *sym_name, void *ctx)
11385 {
11386 	struct avail_kallsyms_data *data = ctx;
11387 	struct kprobe_multi_resolve *res = data->res;
11388 	int err;
11389 
11390 	if (!glob_match(sym_name, res->pattern))
11391 		return 0;
11392 
11393 	if (!bsearch(&sym_name, data->syms, data->cnt, sizeof(*data->syms), avail_func_cmp)) {
11394 		/* Some versions of kernel strip out .llvm.<hash> suffix from
11395 		 * function names reported in available_filter_functions, but
11396 		 * don't do so for kallsyms. While this is clearly a kernel
11397 		 * bug (fixed by [0]) we try to accommodate that in libbpf to
11398 		 * make multi-kprobe usability a bit better: if no match is
11399 		 * found, we will strip .llvm. suffix and try one more time.
11400 		 *
11401 		 *   [0] fb6a421fb615 ("kallsyms: Match symbols exactly with CONFIG_LTO_CLANG")
11402 		 */
11403 		char sym_trim[256], *psym_trim = sym_trim, *sym_sfx;
11404 
11405 		if (!(sym_sfx = strstr(sym_name, ".llvm.")))
11406 			return 0;
11407 
11408 		/* psym_trim vs sym_trim dance is done to avoid pointer vs array
11409 		 * coercion differences and get proper `const char **` pointer
11410 		 * which avail_func_cmp() expects
11411 		 */
11412 		snprintf(sym_trim, sizeof(sym_trim), "%.*s", (int)(sym_sfx - sym_name), sym_name);
11413 		if (!bsearch(&psym_trim, data->syms, data->cnt, sizeof(*data->syms), avail_func_cmp))
11414 			return 0;
11415 	}
11416 
11417 	err = libbpf_ensure_mem((void **)&res->addrs, &res->cap, sizeof(*res->addrs), res->cnt + 1);
11418 	if (err)
11419 		return err;
11420 
11421 	res->addrs[res->cnt++] = (unsigned long)sym_addr;
11422 	return 0;
11423 }
11424 
libbpf_available_kallsyms_parse(struct kprobe_multi_resolve * res)11425 static int libbpf_available_kallsyms_parse(struct kprobe_multi_resolve *res)
11426 {
11427 	const char *available_functions_file = tracefs_available_filter_functions();
11428 	struct avail_kallsyms_data data;
11429 	char sym_name[500];
11430 	FILE *f;
11431 	int err = 0, ret, i;
11432 	char **syms = NULL;
11433 	size_t cap = 0, cnt = 0;
11434 
11435 	f = fopen(available_functions_file, "re");
11436 	if (!f) {
11437 		err = -errno;
11438 		pr_warn("failed to open %s: %s\n", available_functions_file, errstr(err));
11439 		return err;
11440 	}
11441 
11442 	while (true) {
11443 		char *name;
11444 
11445 		ret = fscanf(f, "%499s%*[^\n]\n", sym_name);
11446 		if (ret == EOF && feof(f))
11447 			break;
11448 
11449 		if (ret != 1) {
11450 			pr_warn("failed to parse available_filter_functions entry: %d\n", ret);
11451 			err = -EINVAL;
11452 			goto cleanup;
11453 		}
11454 
11455 		if (!glob_match(sym_name, res->pattern))
11456 			continue;
11457 
11458 		err = libbpf_ensure_mem((void **)&syms, &cap, sizeof(*syms), cnt + 1);
11459 		if (err)
11460 			goto cleanup;
11461 
11462 		name = strdup(sym_name);
11463 		if (!name) {
11464 			err = -errno;
11465 			goto cleanup;
11466 		}
11467 
11468 		syms[cnt++] = name;
11469 	}
11470 
11471 	/* no entries found, bail out */
11472 	if (cnt == 0) {
11473 		err = -ENOENT;
11474 		goto cleanup;
11475 	}
11476 
11477 	/* sort available functions */
11478 	qsort(syms, cnt, sizeof(*syms), avail_func_cmp);
11479 
11480 	data.syms = syms;
11481 	data.res = res;
11482 	data.cnt = cnt;
11483 	libbpf_kallsyms_parse(avail_kallsyms_cb, &data);
11484 
11485 	if (res->cnt == 0)
11486 		err = -ENOENT;
11487 
11488 cleanup:
11489 	for (i = 0; i < cnt; i++)
11490 		free((char *)syms[i]);
11491 	free(syms);
11492 
11493 	fclose(f);
11494 	return err;
11495 }
11496 
has_available_filter_functions_addrs(void)11497 static bool has_available_filter_functions_addrs(void)
11498 {
11499 	return access(tracefs_available_filter_functions_addrs(), R_OK) != -1;
11500 }
11501 
libbpf_available_kprobes_parse(struct kprobe_multi_resolve * res)11502 static int libbpf_available_kprobes_parse(struct kprobe_multi_resolve *res)
11503 {
11504 	const char *available_path = tracefs_available_filter_functions_addrs();
11505 	char sym_name[500];
11506 	FILE *f;
11507 	int ret, err = 0;
11508 	unsigned long long sym_addr;
11509 
11510 	f = fopen(available_path, "re");
11511 	if (!f) {
11512 		err = -errno;
11513 		pr_warn("failed to open %s: %s\n", available_path, errstr(err));
11514 		return err;
11515 	}
11516 
11517 	while (true) {
11518 		ret = fscanf(f, "%llx %499s%*[^\n]\n", &sym_addr, sym_name);
11519 		if (ret == EOF && feof(f))
11520 			break;
11521 
11522 		if (ret != 2) {
11523 			pr_warn("failed to parse available_filter_functions_addrs entry: %d\n",
11524 				ret);
11525 			err = -EINVAL;
11526 			goto cleanup;
11527 		}
11528 
11529 		if (!glob_match(sym_name, res->pattern))
11530 			continue;
11531 
11532 		err = libbpf_ensure_mem((void **)&res->addrs, &res->cap,
11533 					sizeof(*res->addrs), res->cnt + 1);
11534 		if (err)
11535 			goto cleanup;
11536 
11537 		res->addrs[res->cnt++] = (unsigned long)sym_addr;
11538 	}
11539 
11540 	if (res->cnt == 0)
11541 		err = -ENOENT;
11542 
11543 cleanup:
11544 	fclose(f);
11545 	return err;
11546 }
11547 
11548 struct bpf_link *
bpf_program__attach_kprobe_multi_opts(const struct bpf_program * prog,const char * pattern,const struct bpf_kprobe_multi_opts * opts)11549 bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
11550 				      const char *pattern,
11551 				      const struct bpf_kprobe_multi_opts *opts)
11552 {
11553 	LIBBPF_OPTS(bpf_link_create_opts, lopts);
11554 	struct kprobe_multi_resolve res = {
11555 		.pattern = pattern,
11556 	};
11557 	enum bpf_attach_type attach_type;
11558 	struct bpf_link *link = NULL;
11559 	const unsigned long *addrs;
11560 	int err, link_fd, prog_fd;
11561 	bool retprobe, session, unique_match;
11562 	const __u64 *cookies;
11563 	const char **syms;
11564 	size_t cnt;
11565 
11566 	if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
11567 		return libbpf_err_ptr(-EINVAL);
11568 
11569 	prog_fd = bpf_program__fd(prog);
11570 	if (prog_fd < 0) {
11571 		pr_warn("prog '%s': can't attach BPF program without FD (was it loaded?)\n",
11572 			prog->name);
11573 		return libbpf_err_ptr(-EINVAL);
11574 	}
11575 
11576 	syms    = OPTS_GET(opts, syms, false);
11577 	addrs   = OPTS_GET(opts, addrs, false);
11578 	cnt     = OPTS_GET(opts, cnt, false);
11579 	cookies = OPTS_GET(opts, cookies, false);
11580 	unique_match = OPTS_GET(opts, unique_match, false);
11581 
11582 	if (!pattern && !addrs && !syms)
11583 		return libbpf_err_ptr(-EINVAL);
11584 	if (pattern && (addrs || syms || cookies || cnt))
11585 		return libbpf_err_ptr(-EINVAL);
11586 	if (!pattern && !cnt)
11587 		return libbpf_err_ptr(-EINVAL);
11588 	if (!pattern && unique_match)
11589 		return libbpf_err_ptr(-EINVAL);
11590 	if (addrs && syms)
11591 		return libbpf_err_ptr(-EINVAL);
11592 
11593 	if (pattern) {
11594 		if (has_available_filter_functions_addrs())
11595 			err = libbpf_available_kprobes_parse(&res);
11596 		else
11597 			err = libbpf_available_kallsyms_parse(&res);
11598 		if (err)
11599 			goto error;
11600 
11601 		if (unique_match && res.cnt != 1) {
11602 			pr_warn("prog '%s': failed to find a unique match for '%s' (%zu matches)\n",
11603 				prog->name, pattern, res.cnt);
11604 			err = -EINVAL;
11605 			goto error;
11606 		}
11607 
11608 		addrs = res.addrs;
11609 		cnt = res.cnt;
11610 	}
11611 
11612 	retprobe = OPTS_GET(opts, retprobe, false);
11613 	session  = OPTS_GET(opts, session, false);
11614 
11615 	if (retprobe && session)
11616 		return libbpf_err_ptr(-EINVAL);
11617 
11618 	attach_type = session ? BPF_TRACE_KPROBE_SESSION : BPF_TRACE_KPROBE_MULTI;
11619 
11620 	lopts.kprobe_multi.syms = syms;
11621 	lopts.kprobe_multi.addrs = addrs;
11622 	lopts.kprobe_multi.cookies = cookies;
11623 	lopts.kprobe_multi.cnt = cnt;
11624 	lopts.kprobe_multi.flags = retprobe ? BPF_F_KPROBE_MULTI_RETURN : 0;
11625 
11626 	link = calloc(1, sizeof(*link));
11627 	if (!link) {
11628 		err = -ENOMEM;
11629 		goto error;
11630 	}
11631 	link->detach = &bpf_link__detach_fd;
11632 
11633 	link_fd = bpf_link_create(prog_fd, 0, attach_type, &lopts);
11634 	if (link_fd < 0) {
11635 		err = -errno;
11636 		pr_warn("prog '%s': failed to attach: %s\n",
11637 			prog->name, errstr(err));
11638 		goto error;
11639 	}
11640 	link->fd = link_fd;
11641 	free(res.addrs);
11642 	return link;
11643 
11644 error:
11645 	free(link);
11646 	free(res.addrs);
11647 	return libbpf_err_ptr(err);
11648 }
11649 
attach_kprobe(const struct bpf_program * prog,long cookie,struct bpf_link ** link)11650 static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
11651 {
11652 	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
11653 	unsigned long offset = 0;
11654 	const char *func_name;
11655 	char *func;
11656 	int n;
11657 
11658 	*link = NULL;
11659 
11660 	/* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
11661 	if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
11662 		return 0;
11663 
11664 	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
11665 	if (opts.retprobe)
11666 		func_name = prog->sec_name + sizeof("kretprobe/") - 1;
11667 	else
11668 		func_name = prog->sec_name + sizeof("kprobe/") - 1;
11669 
11670 	n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
11671 	if (n < 1) {
11672 		pr_warn("kprobe name is invalid: %s\n", func_name);
11673 		return -EINVAL;
11674 	}
11675 	if (opts.retprobe && offset != 0) {
11676 		free(func);
11677 		pr_warn("kretprobes do not support offset specification\n");
11678 		return -EINVAL;
11679 	}
11680 
11681 	opts.offset = offset;
11682 	*link = bpf_program__attach_kprobe_opts(prog, func, &opts);
11683 	free(func);
11684 	return libbpf_get_error(*link);
11685 }
11686 
attach_ksyscall(const struct bpf_program * prog,long cookie,struct bpf_link ** link)11687 static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link)
11688 {
11689 	LIBBPF_OPTS(bpf_ksyscall_opts, opts);
11690 	const char *syscall_name;
11691 
11692 	*link = NULL;
11693 
11694 	/* no auto-attach for SEC("ksyscall") and SEC("kretsyscall") */
11695 	if (strcmp(prog->sec_name, "ksyscall") == 0 || strcmp(prog->sec_name, "kretsyscall") == 0)
11696 		return 0;
11697 
11698 	opts.retprobe = str_has_pfx(prog->sec_name, "kretsyscall/");
11699 	if (opts.retprobe)
11700 		syscall_name = prog->sec_name + sizeof("kretsyscall/") - 1;
11701 	else
11702 		syscall_name = prog->sec_name + sizeof("ksyscall/") - 1;
11703 
11704 	*link = bpf_program__attach_ksyscall(prog, syscall_name, &opts);
11705 	return *link ? 0 : -errno;
11706 }
11707 
attach_kprobe_multi(const struct bpf_program * prog,long cookie,struct bpf_link ** link)11708 static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
11709 {
11710 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
11711 	const char *spec;
11712 	char *pattern;
11713 	int n;
11714 
11715 	*link = NULL;
11716 
11717 	/* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
11718 	if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
11719 	    strcmp(prog->sec_name, "kretprobe.multi") == 0)
11720 		return 0;
11721 
11722 	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
11723 	if (opts.retprobe)
11724 		spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
11725 	else
11726 		spec = prog->sec_name + sizeof("kprobe.multi/") - 1;
11727 
11728 	n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
11729 	if (n < 1) {
11730 		pr_warn("kprobe multi pattern is invalid: %s\n", spec);
11731 		return -EINVAL;
11732 	}
11733 
11734 	*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
11735 	free(pattern);
11736 	return libbpf_get_error(*link);
11737 }
11738 
attach_kprobe_session(const struct bpf_program * prog,long cookie,struct bpf_link ** link)11739 static int attach_kprobe_session(const struct bpf_program *prog, long cookie,
11740 				 struct bpf_link **link)
11741 {
11742 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts, .session = true);
11743 	const char *spec;
11744 	char *pattern;
11745 	int n;
11746 
11747 	*link = NULL;
11748 
11749 	/* no auto-attach for SEC("kprobe.session") */
11750 	if (strcmp(prog->sec_name, "kprobe.session") == 0)
11751 		return 0;
11752 
11753 	spec = prog->sec_name + sizeof("kprobe.session/") - 1;
11754 	n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
11755 	if (n < 1) {
11756 		pr_warn("kprobe session pattern is invalid: %s\n", spec);
11757 		return -EINVAL;
11758 	}
11759 
11760 	*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
11761 	free(pattern);
11762 	return *link ? 0 : -errno;
11763 }
11764 
attach_uprobe_multi(const struct bpf_program * prog,long cookie,struct bpf_link ** link)11765 static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
11766 {
11767 	char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
11768 	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
11769 	int n, ret = -EINVAL;
11770 
11771 	*link = NULL;
11772 
11773 	n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[^\n]",
11774 		   &probe_type, &binary_path, &func_name);
11775 	switch (n) {
11776 	case 1:
11777 		/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
11778 		ret = 0;
11779 		break;
11780 	case 3:
11781 		opts.session = str_has_pfx(probe_type, "uprobe.session");
11782 		opts.retprobe = str_has_pfx(probe_type, "uretprobe.multi");
11783 
11784 		*link = bpf_program__attach_uprobe_multi(prog, -1, binary_path, func_name, &opts);
11785 		ret = libbpf_get_error(*link);
11786 		break;
11787 	default:
11788 		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
11789 			prog->sec_name);
11790 		break;
11791 	}
11792 	free(probe_type);
11793 	free(binary_path);
11794 	free(func_name);
11795 	return ret;
11796 }
11797 
gen_uprobe_legacy_event_name(char * buf,size_t buf_sz,const char * binary_path,uint64_t offset)11798 static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
11799 					 const char *binary_path, uint64_t offset)
11800 {
11801 	int i;
11802 
11803 	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), binary_path, (size_t)offset);
11804 
11805 	/* sanitize binary_path in the probe name */
11806 	for (i = 0; buf[i]; i++) {
11807 		if (!isalnum(buf[i]))
11808 			buf[i] = '_';
11809 	}
11810 }
11811 
add_uprobe_event_legacy(const char * probe_name,bool retprobe,const char * binary_path,size_t offset)11812 static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
11813 					  const char *binary_path, size_t offset)
11814 {
11815 	return append_to_file(tracefs_uprobe_events(), "%c:%s/%s %s:0x%zx",
11816 			      retprobe ? 'r' : 'p',
11817 			      retprobe ? "uretprobes" : "uprobes",
11818 			      probe_name, binary_path, offset);
11819 }
11820 
remove_uprobe_event_legacy(const char * probe_name,bool retprobe)11821 static inline int remove_uprobe_event_legacy(const char *probe_name, bool retprobe)
11822 {
11823 	return append_to_file(tracefs_uprobe_events(), "-:%s/%s",
11824 			      retprobe ? "uretprobes" : "uprobes", probe_name);
11825 }
11826 
determine_uprobe_perf_type_legacy(const char * probe_name,bool retprobe)11827 static int determine_uprobe_perf_type_legacy(const char *probe_name, bool retprobe)
11828 {
11829 	char file[512];
11830 
11831 	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
11832 		 tracefs_path(), retprobe ? "uretprobes" : "uprobes", probe_name);
11833 
11834 	return parse_uint_from_file(file, "%d\n");
11835 }
11836 
perf_event_uprobe_open_legacy(const char * probe_name,bool retprobe,const char * binary_path,size_t offset,int pid)11837 static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
11838 					 const char *binary_path, size_t offset, int pid)
11839 {
11840 	const size_t attr_sz = sizeof(struct perf_event_attr);
11841 	struct perf_event_attr attr;
11842 	int type, pfd, err;
11843 
11844 	err = add_uprobe_event_legacy(probe_name, retprobe, binary_path, offset);
11845 	if (err < 0) {
11846 		pr_warn("failed to add legacy uprobe event for %s:0x%zx: %s\n",
11847 			binary_path, (size_t)offset, errstr(err));
11848 		return err;
11849 	}
11850 	type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
11851 	if (type < 0) {
11852 		err = type;
11853 		pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %s\n",
11854 			binary_path, offset, errstr(err));
11855 		goto err_clean_legacy;
11856 	}
11857 
11858 	memset(&attr, 0, attr_sz);
11859 	attr.size = attr_sz;
11860 	attr.config = type;
11861 	attr.type = PERF_TYPE_TRACEPOINT;
11862 
11863 	pfd = syscall(__NR_perf_event_open, &attr,
11864 		      pid < 0 ? -1 : pid, /* pid */
11865 		      pid == -1 ? 0 : -1, /* cpu */
11866 		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
11867 	if (pfd < 0) {
11868 		err = -errno;
11869 		pr_warn("legacy uprobe perf_event_open() failed: %s\n", errstr(err));
11870 		goto err_clean_legacy;
11871 	}
11872 	return pfd;
11873 
11874 err_clean_legacy:
11875 	/* Clear the newly added legacy uprobe_event */
11876 	remove_uprobe_event_legacy(probe_name, retprobe);
11877 	return err;
11878 }
11879 
11880 /* Find offset of function name in archive specified by path. Currently
11881  * supported are .zip files that do not compress their contents, as used on
11882  * Android in the form of APKs, for example. "file_name" is the name of the ELF
11883  * file inside the archive. "func_name" matches symbol name or name@@LIB for
11884  * library functions.
11885  *
11886  * An overview of the APK format specifically provided here:
11887  * https://en.wikipedia.org/w/index.php?title=Apk_(file_format)&oldid=1139099120#Package_contents
11888  */
elf_find_func_offset_from_archive(const char * archive_path,const char * file_name,const char * func_name)11889 static long elf_find_func_offset_from_archive(const char *archive_path, const char *file_name,
11890 					      const char *func_name)
11891 {
11892 	struct zip_archive *archive;
11893 	struct zip_entry entry;
11894 	long ret;
11895 	Elf *elf;
11896 
11897 	archive = zip_archive_open(archive_path);
11898 	if (IS_ERR(archive)) {
11899 		ret = PTR_ERR(archive);
11900 		pr_warn("zip: failed to open %s: %ld\n", archive_path, ret);
11901 		return ret;
11902 	}
11903 
11904 	ret = zip_archive_find_entry(archive, file_name, &entry);
11905 	if (ret) {
11906 		pr_warn("zip: could not find archive member %s in %s: %ld\n", file_name,
11907 			archive_path, ret);
11908 		goto out;
11909 	}
11910 	pr_debug("zip: found entry for %s in %s at 0x%lx\n", file_name, archive_path,
11911 		 (unsigned long)entry.data_offset);
11912 
11913 	if (entry.compression) {
11914 		pr_warn("zip: entry %s of %s is compressed and cannot be handled\n", file_name,
11915 			archive_path);
11916 		ret = -LIBBPF_ERRNO__FORMAT;
11917 		goto out;
11918 	}
11919 
11920 	elf = elf_memory((void *)entry.data, entry.data_length);
11921 	if (!elf) {
11922 		pr_warn("elf: could not read elf file %s from %s: %s\n", file_name, archive_path,
11923 			elf_errmsg(-1));
11924 		ret = -LIBBPF_ERRNO__LIBELF;
11925 		goto out;
11926 	}
11927 
11928 	ret = elf_find_func_offset(elf, file_name, func_name);
11929 	if (ret > 0) {
11930 		pr_debug("elf: symbol address match for %s of %s in %s: 0x%x + 0x%lx = 0x%lx\n",
11931 			 func_name, file_name, archive_path, entry.data_offset, ret,
11932 			 ret + entry.data_offset);
11933 		ret += entry.data_offset;
11934 	}
11935 	elf_end(elf);
11936 
11937 out:
11938 	zip_archive_close(archive);
11939 	return ret;
11940 }
11941 
arch_specific_lib_paths(void)11942 static const char *arch_specific_lib_paths(void)
11943 {
11944 	/*
11945 	 * Based on https://packages.debian.org/sid/libc6.
11946 	 *
11947 	 * Assume that the traced program is built for the same architecture
11948 	 * as libbpf, which should cover the vast majority of cases.
11949 	 */
11950 #if defined(__x86_64__)
11951 	return "/lib/x86_64-linux-gnu";
11952 #elif defined(__i386__)
11953 	return "/lib/i386-linux-gnu";
11954 #elif defined(__s390x__)
11955 	return "/lib/s390x-linux-gnu";
11956 #elif defined(__s390__)
11957 	return "/lib/s390-linux-gnu";
11958 #elif defined(__arm__) && defined(__SOFTFP__)
11959 	return "/lib/arm-linux-gnueabi";
11960 #elif defined(__arm__) && !defined(__SOFTFP__)
11961 	return "/lib/arm-linux-gnueabihf";
11962 #elif defined(__aarch64__)
11963 	return "/lib/aarch64-linux-gnu";
11964 #elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 64
11965 	return "/lib/mips64el-linux-gnuabi64";
11966 #elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 32
11967 	return "/lib/mipsel-linux-gnu";
11968 #elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
11969 	return "/lib/powerpc64le-linux-gnu";
11970 #elif defined(__sparc__) && defined(__arch64__)
11971 	return "/lib/sparc64-linux-gnu";
11972 #elif defined(__riscv) && __riscv_xlen == 64
11973 	return "/lib/riscv64-linux-gnu";
11974 #else
11975 	return NULL;
11976 #endif
11977 }
11978 
11979 /* Get full path to program/shared library. */
resolve_full_path(const char * file,char * result,size_t result_sz)11980 static int resolve_full_path(const char *file, char *result, size_t result_sz)
11981 {
11982 	const char *search_paths[3] = {};
11983 	int i, perm;
11984 
11985 	if (str_has_sfx(file, ".so") || strstr(file, ".so.")) {
11986 		search_paths[0] = getenv("LD_LIBRARY_PATH");
11987 		search_paths[1] = "/usr/lib64:/usr/lib";
11988 		search_paths[2] = arch_specific_lib_paths();
11989 		perm = R_OK;
11990 	} else {
11991 		search_paths[0] = getenv("PATH");
11992 		search_paths[1] = "/usr/bin:/usr/sbin";
11993 		perm = R_OK | X_OK;
11994 	}
11995 
11996 	for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
11997 		const char *s;
11998 
11999 		if (!search_paths[i])
12000 			continue;
12001 		for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
12002 			char *next_path;
12003 			int seg_len;
12004 
12005 			if (s[0] == ':')
12006 				s++;
12007 			next_path = strchr(s, ':');
12008 			seg_len = next_path ? next_path - s : strlen(s);
12009 			if (!seg_len)
12010 				continue;
12011 			snprintf(result, result_sz, "%.*s/%s", seg_len, s, file);
12012 			/* ensure it has required permissions */
12013 			if (faccessat(AT_FDCWD, result, perm, AT_EACCESS) < 0)
12014 				continue;
12015 			pr_debug("resolved '%s' to '%s'\n", file, result);
12016 			return 0;
12017 		}
12018 	}
12019 	return -ENOENT;
12020 }
12021 
12022 struct bpf_link *
bpf_program__attach_uprobe_multi(const struct bpf_program * prog,pid_t pid,const char * path,const char * func_pattern,const struct bpf_uprobe_multi_opts * opts)12023 bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
12024 				 pid_t pid,
12025 				 const char *path,
12026 				 const char *func_pattern,
12027 				 const struct bpf_uprobe_multi_opts *opts)
12028 {
12029 	const unsigned long *ref_ctr_offsets = NULL, *offsets = NULL;
12030 	LIBBPF_OPTS(bpf_link_create_opts, lopts);
12031 	unsigned long *resolved_offsets = NULL;
12032 	enum bpf_attach_type attach_type;
12033 	int err = 0, link_fd, prog_fd;
12034 	struct bpf_link *link = NULL;
12035 	char full_path[PATH_MAX];
12036 	bool retprobe, session;
12037 	const __u64 *cookies;
12038 	const char **syms;
12039 	size_t cnt;
12040 
12041 	if (!OPTS_VALID(opts, bpf_uprobe_multi_opts))
12042 		return libbpf_err_ptr(-EINVAL);
12043 
12044 	prog_fd = bpf_program__fd(prog);
12045 	if (prog_fd < 0) {
12046 		pr_warn("prog '%s': can't attach BPF program without FD (was it loaded?)\n",
12047 			prog->name);
12048 		return libbpf_err_ptr(-EINVAL);
12049 	}
12050 
12051 	syms = OPTS_GET(opts, syms, NULL);
12052 	offsets = OPTS_GET(opts, offsets, NULL);
12053 	ref_ctr_offsets = OPTS_GET(opts, ref_ctr_offsets, NULL);
12054 	cookies = OPTS_GET(opts, cookies, NULL);
12055 	cnt = OPTS_GET(opts, cnt, 0);
12056 	retprobe = OPTS_GET(opts, retprobe, false);
12057 	session  = OPTS_GET(opts, session, false);
12058 
12059 	/*
12060 	 * User can specify 2 mutually exclusive set of inputs:
12061 	 *
12062 	 * 1) use only path/func_pattern/pid arguments
12063 	 *
12064 	 * 2) use path/pid with allowed combinations of:
12065 	 *    syms/offsets/ref_ctr_offsets/cookies/cnt
12066 	 *
12067 	 *    - syms and offsets are mutually exclusive
12068 	 *    - ref_ctr_offsets and cookies are optional
12069 	 *
12070 	 * Any other usage results in error.
12071 	 */
12072 
12073 	if (!path)
12074 		return libbpf_err_ptr(-EINVAL);
12075 	if (!func_pattern && cnt == 0)
12076 		return libbpf_err_ptr(-EINVAL);
12077 
12078 	if (func_pattern) {
12079 		if (syms || offsets || ref_ctr_offsets || cookies || cnt)
12080 			return libbpf_err_ptr(-EINVAL);
12081 	} else {
12082 		if (!!syms == !!offsets)
12083 			return libbpf_err_ptr(-EINVAL);
12084 	}
12085 
12086 	if (retprobe && session)
12087 		return libbpf_err_ptr(-EINVAL);
12088 
12089 	if (func_pattern) {
12090 		if (!strchr(path, '/')) {
12091 			err = resolve_full_path(path, full_path, sizeof(full_path));
12092 			if (err) {
12093 				pr_warn("prog '%s': failed to resolve full path for '%s': %s\n",
12094 					prog->name, path, errstr(err));
12095 				return libbpf_err_ptr(err);
12096 			}
12097 			path = full_path;
12098 		}
12099 
12100 		err = elf_resolve_pattern_offsets(path, func_pattern,
12101 						  &resolved_offsets, &cnt);
12102 		if (err < 0)
12103 			return libbpf_err_ptr(err);
12104 		offsets = resolved_offsets;
12105 	} else if (syms) {
12106 		err = elf_resolve_syms_offsets(path, cnt, syms, &resolved_offsets, STT_FUNC);
12107 		if (err < 0)
12108 			return libbpf_err_ptr(err);
12109 		offsets = resolved_offsets;
12110 	}
12111 
12112 	attach_type = session ? BPF_TRACE_UPROBE_SESSION : BPF_TRACE_UPROBE_MULTI;
12113 
12114 	lopts.uprobe_multi.path = path;
12115 	lopts.uprobe_multi.offsets = offsets;
12116 	lopts.uprobe_multi.ref_ctr_offsets = ref_ctr_offsets;
12117 	lopts.uprobe_multi.cookies = cookies;
12118 	lopts.uprobe_multi.cnt = cnt;
12119 	lopts.uprobe_multi.flags = retprobe ? BPF_F_UPROBE_MULTI_RETURN : 0;
12120 
12121 	if (pid == 0)
12122 		pid = getpid();
12123 	if (pid > 0)
12124 		lopts.uprobe_multi.pid = pid;
12125 
12126 	link = calloc(1, sizeof(*link));
12127 	if (!link) {
12128 		err = -ENOMEM;
12129 		goto error;
12130 	}
12131 	link->detach = &bpf_link__detach_fd;
12132 
12133 	link_fd = bpf_link_create(prog_fd, 0, attach_type, &lopts);
12134 	if (link_fd < 0) {
12135 		err = -errno;
12136 		pr_warn("prog '%s': failed to attach multi-uprobe: %s\n",
12137 			prog->name, errstr(err));
12138 		goto error;
12139 	}
12140 	link->fd = link_fd;
12141 	free(resolved_offsets);
12142 	return link;
12143 
12144 error:
12145 	free(resolved_offsets);
12146 	free(link);
12147 	return libbpf_err_ptr(err);
12148 }
12149 
12150 LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe_opts(const struct bpf_program * prog,pid_t pid,const char * binary_path,size_t func_offset,const struct bpf_uprobe_opts * opts)12151 bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
12152 				const char *binary_path, size_t func_offset,
12153 				const struct bpf_uprobe_opts *opts)
12154 {
12155 	const char *archive_path = NULL, *archive_sep = NULL;
12156 	char *legacy_probe = NULL;
12157 	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
12158 	enum probe_attach_mode attach_mode;
12159 	char full_path[PATH_MAX];
12160 	struct bpf_link *link;
12161 	size_t ref_ctr_off;
12162 	int pfd, err;
12163 	bool retprobe, legacy;
12164 	const char *func_name;
12165 
12166 	if (!OPTS_VALID(opts, bpf_uprobe_opts))
12167 		return libbpf_err_ptr(-EINVAL);
12168 
12169 	attach_mode = OPTS_GET(opts, attach_mode, PROBE_ATTACH_MODE_DEFAULT);
12170 	retprobe = OPTS_GET(opts, retprobe, false);
12171 	ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
12172 	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
12173 
12174 	if (!binary_path)
12175 		return libbpf_err_ptr(-EINVAL);
12176 
12177 	/* Check if "binary_path" refers to an archive. */
12178 	archive_sep = strstr(binary_path, "!/");
12179 	if (archive_sep) {
12180 		full_path[0] = '\0';
12181 		libbpf_strlcpy(full_path, binary_path,
12182 			       min(sizeof(full_path), (size_t)(archive_sep - binary_path + 1)));
12183 		archive_path = full_path;
12184 		binary_path = archive_sep + 2;
12185 	} else if (!strchr(binary_path, '/')) {
12186 		err = resolve_full_path(binary_path, full_path, sizeof(full_path));
12187 		if (err) {
12188 			pr_warn("prog '%s': failed to resolve full path for '%s': %s\n",
12189 				prog->name, binary_path, errstr(err));
12190 			return libbpf_err_ptr(err);
12191 		}
12192 		binary_path = full_path;
12193 	}
12194 	func_name = OPTS_GET(opts, func_name, NULL);
12195 	if (func_name) {
12196 		long sym_off;
12197 
12198 		if (archive_path) {
12199 			sym_off = elf_find_func_offset_from_archive(archive_path, binary_path,
12200 								    func_name);
12201 			binary_path = archive_path;
12202 		} else {
12203 			sym_off = elf_find_func_offset_from_file(binary_path, func_name);
12204 		}
12205 		if (sym_off < 0)
12206 			return libbpf_err_ptr(sym_off);
12207 		func_offset += sym_off;
12208 	}
12209 
12210 	legacy = determine_uprobe_perf_type() < 0;
12211 	switch (attach_mode) {
12212 	case PROBE_ATTACH_MODE_LEGACY:
12213 		legacy = true;
12214 		pe_opts.force_ioctl_attach = true;
12215 		break;
12216 	case PROBE_ATTACH_MODE_PERF:
12217 		if (legacy)
12218 			return libbpf_err_ptr(-ENOTSUP);
12219 		pe_opts.force_ioctl_attach = true;
12220 		break;
12221 	case PROBE_ATTACH_MODE_LINK:
12222 		if (legacy || !kernel_supports(prog->obj, FEAT_PERF_LINK))
12223 			return libbpf_err_ptr(-ENOTSUP);
12224 		break;
12225 	case PROBE_ATTACH_MODE_DEFAULT:
12226 		break;
12227 	default:
12228 		return libbpf_err_ptr(-EINVAL);
12229 	}
12230 
12231 	if (!legacy) {
12232 		pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
12233 					    func_offset, pid, ref_ctr_off);
12234 	} else {
12235 		char probe_name[PATH_MAX + 64];
12236 
12237 		if (ref_ctr_off)
12238 			return libbpf_err_ptr(-EINVAL);
12239 
12240 		gen_uprobe_legacy_event_name(probe_name, sizeof(probe_name),
12241 					     binary_path, func_offset);
12242 
12243 		legacy_probe = strdup(probe_name);
12244 		if (!legacy_probe)
12245 			return libbpf_err_ptr(-ENOMEM);
12246 
12247 		pfd = perf_event_uprobe_open_legacy(legacy_probe, retprobe,
12248 						    binary_path, func_offset, pid);
12249 	}
12250 	if (pfd < 0) {
12251 		err = -errno;
12252 		pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
12253 			prog->name, retprobe ? "uretprobe" : "uprobe",
12254 			binary_path, func_offset,
12255 			errstr(err));
12256 		goto err_out;
12257 	}
12258 
12259 	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
12260 	err = libbpf_get_error(link);
12261 	if (err) {
12262 		close(pfd);
12263 		pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
12264 			prog->name, retprobe ? "uretprobe" : "uprobe",
12265 			binary_path, func_offset,
12266 			errstr(err));
12267 		goto err_clean_legacy;
12268 	}
12269 	if (legacy) {
12270 		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
12271 
12272 		perf_link->legacy_probe_name = legacy_probe;
12273 		perf_link->legacy_is_kprobe = false;
12274 		perf_link->legacy_is_retprobe = retprobe;
12275 	}
12276 	return link;
12277 
12278 err_clean_legacy:
12279 	if (legacy)
12280 		remove_uprobe_event_legacy(legacy_probe, retprobe);
12281 err_out:
12282 	free(legacy_probe);
12283 	return libbpf_err_ptr(err);
12284 }
12285 
12286 /* Format of u[ret]probe section definition supporting auto-attach:
12287  * u[ret]probe/binary:function[+offset]
12288  *
12289  * binary can be an absolute/relative path or a filename; the latter is resolved to a
12290  * full binary path via bpf_program__attach_uprobe_opts.
12291  *
12292  * Specifying uprobe+ ensures we carry out strict matching; either "uprobe" must be
12293  * specified (and auto-attach is not possible) or the above format is specified for
12294  * auto-attach.
12295  */
attach_uprobe(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12296 static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12297 {
12298 	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
12299 	char *probe_type = NULL, *binary_path = NULL, *func_name = NULL, *func_off;
12300 	int n, c, ret = -EINVAL;
12301 	long offset = 0;
12302 
12303 	*link = NULL;
12304 
12305 	n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[^\n]",
12306 		   &probe_type, &binary_path, &func_name);
12307 	switch (n) {
12308 	case 1:
12309 		/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
12310 		ret = 0;
12311 		break;
12312 	case 2:
12313 		pr_warn("prog '%s': section '%s' missing ':function[+offset]' specification\n",
12314 			prog->name, prog->sec_name);
12315 		break;
12316 	case 3:
12317 		/* check if user specifies `+offset`, if yes, this should be
12318 		 * the last part of the string, make sure sscanf read to EOL
12319 		 */
12320 		func_off = strrchr(func_name, '+');
12321 		if (func_off) {
12322 			n = sscanf(func_off, "+%li%n", &offset, &c);
12323 			if (n == 1 && *(func_off + c) == '\0')
12324 				func_off[0] = '\0';
12325 			else
12326 				offset = 0;
12327 		}
12328 		opts.retprobe = strcmp(probe_type, "uretprobe") == 0 ||
12329 				strcmp(probe_type, "uretprobe.s") == 0;
12330 		if (opts.retprobe && offset != 0) {
12331 			pr_warn("prog '%s': uretprobes do not support offset specification\n",
12332 				prog->name);
12333 			break;
12334 		}
12335 		opts.func_name = func_name;
12336 		*link = bpf_program__attach_uprobe_opts(prog, -1, binary_path, offset, &opts);
12337 		ret = libbpf_get_error(*link);
12338 		break;
12339 	default:
12340 		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
12341 			prog->sec_name);
12342 		break;
12343 	}
12344 	free(probe_type);
12345 	free(binary_path);
12346 	free(func_name);
12347 
12348 	return ret;
12349 }
12350 
bpf_program__attach_uprobe(const struct bpf_program * prog,bool retprobe,pid_t pid,const char * binary_path,size_t func_offset)12351 struct bpf_link *bpf_program__attach_uprobe(const struct bpf_program *prog,
12352 					    bool retprobe, pid_t pid,
12353 					    const char *binary_path,
12354 					    size_t func_offset)
12355 {
12356 	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
12357 
12358 	return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
12359 }
12360 
bpf_program__attach_usdt(const struct bpf_program * prog,pid_t pid,const char * binary_path,const char * usdt_provider,const char * usdt_name,const struct bpf_usdt_opts * opts)12361 struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
12362 					  pid_t pid, const char *binary_path,
12363 					  const char *usdt_provider, const char *usdt_name,
12364 					  const struct bpf_usdt_opts *opts)
12365 {
12366 	char resolved_path[512];
12367 	struct bpf_object *obj = prog->obj;
12368 	struct bpf_link *link;
12369 	__u64 usdt_cookie;
12370 	int err;
12371 
12372 	if (!OPTS_VALID(opts, bpf_uprobe_opts))
12373 		return libbpf_err_ptr(-EINVAL);
12374 
12375 	if (bpf_program__fd(prog) < 0) {
12376 		pr_warn("prog '%s': can't attach BPF program without FD (was it loaded?)\n",
12377 			prog->name);
12378 		return libbpf_err_ptr(-EINVAL);
12379 	}
12380 
12381 	if (!binary_path)
12382 		return libbpf_err_ptr(-EINVAL);
12383 
12384 	if (!strchr(binary_path, '/')) {
12385 		err = resolve_full_path(binary_path, resolved_path, sizeof(resolved_path));
12386 		if (err) {
12387 			pr_warn("prog '%s': failed to resolve full path for '%s': %s\n",
12388 				prog->name, binary_path, errstr(err));
12389 			return libbpf_err_ptr(err);
12390 		}
12391 		binary_path = resolved_path;
12392 	}
12393 
12394 	/* USDT manager is instantiated lazily on first USDT attach. It will
12395 	 * be destroyed together with BPF object in bpf_object__close().
12396 	 */
12397 	if (IS_ERR(obj->usdt_man))
12398 		return libbpf_ptr(obj->usdt_man);
12399 	if (!obj->usdt_man) {
12400 		obj->usdt_man = usdt_manager_new(obj);
12401 		if (IS_ERR(obj->usdt_man))
12402 			return libbpf_ptr(obj->usdt_man);
12403 	}
12404 
12405 	usdt_cookie = OPTS_GET(opts, usdt_cookie, 0);
12406 	link = usdt_manager_attach_usdt(obj->usdt_man, prog, pid, binary_path,
12407 					usdt_provider, usdt_name, usdt_cookie);
12408 	err = libbpf_get_error(link);
12409 	if (err)
12410 		return libbpf_err_ptr(err);
12411 	return link;
12412 }
12413 
attach_usdt(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12414 static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12415 {
12416 	char *path = NULL, *provider = NULL, *name = NULL;
12417 	const char *sec_name;
12418 	int n, err;
12419 
12420 	sec_name = bpf_program__section_name(prog);
12421 	if (strcmp(sec_name, "usdt") == 0) {
12422 		/* no auto-attach for just SEC("usdt") */
12423 		*link = NULL;
12424 		return 0;
12425 	}
12426 
12427 	n = sscanf(sec_name, "usdt/%m[^:]:%m[^:]:%m[^:]", &path, &provider, &name);
12428 	if (n != 3) {
12429 		pr_warn("invalid section '%s', expected SEC(\"usdt/<path>:<provider>:<name>\")\n",
12430 			sec_name);
12431 		err = -EINVAL;
12432 	} else {
12433 		*link = bpf_program__attach_usdt(prog, -1 /* any process */, path,
12434 						 provider, name, NULL);
12435 		err = libbpf_get_error(*link);
12436 	}
12437 	free(path);
12438 	free(provider);
12439 	free(name);
12440 	return err;
12441 }
12442 
determine_tracepoint_id(const char * tp_category,const char * tp_name)12443 static int determine_tracepoint_id(const char *tp_category,
12444 				   const char *tp_name)
12445 {
12446 	char file[PATH_MAX];
12447 	int ret;
12448 
12449 	ret = snprintf(file, sizeof(file), "%s/events/%s/%s/id",
12450 		       tracefs_path(), tp_category, tp_name);
12451 	if (ret < 0)
12452 		return -errno;
12453 	if (ret >= sizeof(file)) {
12454 		pr_debug("tracepoint %s/%s path is too long\n",
12455 			 tp_category, tp_name);
12456 		return -E2BIG;
12457 	}
12458 	return parse_uint_from_file(file, "%d\n");
12459 }
12460 
perf_event_open_tracepoint(const char * tp_category,const char * tp_name)12461 static int perf_event_open_tracepoint(const char *tp_category,
12462 				      const char *tp_name)
12463 {
12464 	const size_t attr_sz = sizeof(struct perf_event_attr);
12465 	struct perf_event_attr attr;
12466 	int tp_id, pfd, err;
12467 
12468 	tp_id = determine_tracepoint_id(tp_category, tp_name);
12469 	if (tp_id < 0) {
12470 		pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
12471 			tp_category, tp_name,
12472 			errstr(tp_id));
12473 		return tp_id;
12474 	}
12475 
12476 	memset(&attr, 0, attr_sz);
12477 	attr.type = PERF_TYPE_TRACEPOINT;
12478 	attr.size = attr_sz;
12479 	attr.config = tp_id;
12480 
12481 	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
12482 		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
12483 	if (pfd < 0) {
12484 		err = -errno;
12485 		pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
12486 			tp_category, tp_name,
12487 			errstr(err));
12488 		return err;
12489 	}
12490 	return pfd;
12491 }
12492 
bpf_program__attach_tracepoint_opts(const struct bpf_program * prog,const char * tp_category,const char * tp_name,const struct bpf_tracepoint_opts * opts)12493 struct bpf_link *bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
12494 						     const char *tp_category,
12495 						     const char *tp_name,
12496 						     const struct bpf_tracepoint_opts *opts)
12497 {
12498 	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
12499 	struct bpf_link *link;
12500 	int pfd, err;
12501 
12502 	if (!OPTS_VALID(opts, bpf_tracepoint_opts))
12503 		return libbpf_err_ptr(-EINVAL);
12504 
12505 	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
12506 
12507 	pfd = perf_event_open_tracepoint(tp_category, tp_name);
12508 	if (pfd < 0) {
12509 		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
12510 			prog->name, tp_category, tp_name,
12511 			errstr(pfd));
12512 		return libbpf_err_ptr(pfd);
12513 	}
12514 	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
12515 	err = libbpf_get_error(link);
12516 	if (err) {
12517 		close(pfd);
12518 		pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
12519 			prog->name, tp_category, tp_name,
12520 			errstr(err));
12521 		return libbpf_err_ptr(err);
12522 	}
12523 	return link;
12524 }
12525 
bpf_program__attach_tracepoint(const struct bpf_program * prog,const char * tp_category,const char * tp_name)12526 struct bpf_link *bpf_program__attach_tracepoint(const struct bpf_program *prog,
12527 						const char *tp_category,
12528 						const char *tp_name)
12529 {
12530 	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
12531 }
12532 
attach_tp(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12533 static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12534 {
12535 	char *sec_name, *tp_cat, *tp_name;
12536 
12537 	*link = NULL;
12538 
12539 	/* no auto-attach for SEC("tp") or SEC("tracepoint") */
12540 	if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
12541 		return 0;
12542 
12543 	sec_name = strdup(prog->sec_name);
12544 	if (!sec_name)
12545 		return -ENOMEM;
12546 
12547 	/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
12548 	if (str_has_pfx(prog->sec_name, "tp/"))
12549 		tp_cat = sec_name + sizeof("tp/") - 1;
12550 	else
12551 		tp_cat = sec_name + sizeof("tracepoint/") - 1;
12552 	tp_name = strchr(tp_cat, '/');
12553 	if (!tp_name) {
12554 		free(sec_name);
12555 		return -EINVAL;
12556 	}
12557 	*tp_name = '\0';
12558 	tp_name++;
12559 
12560 	*link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
12561 	free(sec_name);
12562 	return libbpf_get_error(*link);
12563 }
12564 
12565 struct bpf_link *
bpf_program__attach_raw_tracepoint_opts(const struct bpf_program * prog,const char * tp_name,struct bpf_raw_tracepoint_opts * opts)12566 bpf_program__attach_raw_tracepoint_opts(const struct bpf_program *prog,
12567 					const char *tp_name,
12568 					struct bpf_raw_tracepoint_opts *opts)
12569 {
12570 	LIBBPF_OPTS(bpf_raw_tp_opts, raw_opts);
12571 	struct bpf_link *link;
12572 	int prog_fd, pfd;
12573 
12574 	if (!OPTS_VALID(opts, bpf_raw_tracepoint_opts))
12575 		return libbpf_err_ptr(-EINVAL);
12576 
12577 	prog_fd = bpf_program__fd(prog);
12578 	if (prog_fd < 0) {
12579 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
12580 		return libbpf_err_ptr(-EINVAL);
12581 	}
12582 
12583 	link = calloc(1, sizeof(*link));
12584 	if (!link)
12585 		return libbpf_err_ptr(-ENOMEM);
12586 	link->detach = &bpf_link__detach_fd;
12587 
12588 	raw_opts.tp_name = tp_name;
12589 	raw_opts.cookie = OPTS_GET(opts, cookie, 0);
12590 	pfd = bpf_raw_tracepoint_open_opts(prog_fd, &raw_opts);
12591 	if (pfd < 0) {
12592 		pfd = -errno;
12593 		free(link);
12594 		pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
12595 			prog->name, tp_name, errstr(pfd));
12596 		return libbpf_err_ptr(pfd);
12597 	}
12598 	link->fd = pfd;
12599 	return link;
12600 }
12601 
bpf_program__attach_raw_tracepoint(const struct bpf_program * prog,const char * tp_name)12602 struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
12603 						    const char *tp_name)
12604 {
12605 	return bpf_program__attach_raw_tracepoint_opts(prog, tp_name, NULL);
12606 }
12607 
attach_raw_tp(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12608 static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12609 {
12610 	static const char *const prefixes[] = {
12611 		"raw_tp",
12612 		"raw_tracepoint",
12613 		"raw_tp.w",
12614 		"raw_tracepoint.w",
12615 	};
12616 	size_t i;
12617 	const char *tp_name = NULL;
12618 
12619 	*link = NULL;
12620 
12621 	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
12622 		size_t pfx_len;
12623 
12624 		if (!str_has_pfx(prog->sec_name, prefixes[i]))
12625 			continue;
12626 
12627 		pfx_len = strlen(prefixes[i]);
12628 		/* no auto-attach case of, e.g., SEC("raw_tp") */
12629 		if (prog->sec_name[pfx_len] == '\0')
12630 			return 0;
12631 
12632 		if (prog->sec_name[pfx_len] != '/')
12633 			continue;
12634 
12635 		tp_name = prog->sec_name + pfx_len + 1;
12636 		break;
12637 	}
12638 
12639 	if (!tp_name) {
12640 		pr_warn("prog '%s': invalid section name '%s'\n",
12641 			prog->name, prog->sec_name);
12642 		return -EINVAL;
12643 	}
12644 
12645 	*link = bpf_program__attach_raw_tracepoint(prog, tp_name);
12646 	return libbpf_get_error(*link);
12647 }
12648 
12649 /* Common logic for all BPF program types that attach to a btf_id */
bpf_program__attach_btf_id(const struct bpf_program * prog,const struct bpf_trace_opts * opts)12650 static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
12651 						   const struct bpf_trace_opts *opts)
12652 {
12653 	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
12654 	struct bpf_link *link;
12655 	int prog_fd, pfd;
12656 
12657 	if (!OPTS_VALID(opts, bpf_trace_opts))
12658 		return libbpf_err_ptr(-EINVAL);
12659 
12660 	prog_fd = bpf_program__fd(prog);
12661 	if (prog_fd < 0) {
12662 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
12663 		return libbpf_err_ptr(-EINVAL);
12664 	}
12665 
12666 	link = calloc(1, sizeof(*link));
12667 	if (!link)
12668 		return libbpf_err_ptr(-ENOMEM);
12669 	link->detach = &bpf_link__detach_fd;
12670 
12671 	/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
12672 	link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
12673 	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
12674 	if (pfd < 0) {
12675 		pfd = -errno;
12676 		free(link);
12677 		pr_warn("prog '%s': failed to attach: %s\n",
12678 			prog->name, errstr(pfd));
12679 		return libbpf_err_ptr(pfd);
12680 	}
12681 	link->fd = pfd;
12682 	return link;
12683 }
12684 
bpf_program__attach_trace(const struct bpf_program * prog)12685 struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
12686 {
12687 	return bpf_program__attach_btf_id(prog, NULL);
12688 }
12689 
bpf_program__attach_trace_opts(const struct bpf_program * prog,const struct bpf_trace_opts * opts)12690 struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
12691 						const struct bpf_trace_opts *opts)
12692 {
12693 	return bpf_program__attach_btf_id(prog, opts);
12694 }
12695 
bpf_program__attach_lsm(const struct bpf_program * prog)12696 struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
12697 {
12698 	return bpf_program__attach_btf_id(prog, NULL);
12699 }
12700 
attach_trace(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12701 static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12702 {
12703 	*link = bpf_program__attach_trace(prog);
12704 	return libbpf_get_error(*link);
12705 }
12706 
attach_lsm(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12707 static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12708 {
12709 	*link = bpf_program__attach_lsm(prog);
12710 	return libbpf_get_error(*link);
12711 }
12712 
12713 static struct bpf_link *
bpf_program_attach_fd(const struct bpf_program * prog,int target_fd,const char * target_name,const struct bpf_link_create_opts * opts)12714 bpf_program_attach_fd(const struct bpf_program *prog,
12715 		      int target_fd, const char *target_name,
12716 		      const struct bpf_link_create_opts *opts)
12717 {
12718 	enum bpf_attach_type attach_type;
12719 	struct bpf_link *link;
12720 	int prog_fd, link_fd;
12721 
12722 	prog_fd = bpf_program__fd(prog);
12723 	if (prog_fd < 0) {
12724 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
12725 		return libbpf_err_ptr(-EINVAL);
12726 	}
12727 
12728 	link = calloc(1, sizeof(*link));
12729 	if (!link)
12730 		return libbpf_err_ptr(-ENOMEM);
12731 	link->detach = &bpf_link__detach_fd;
12732 
12733 	attach_type = bpf_program__expected_attach_type(prog);
12734 	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, opts);
12735 	if (link_fd < 0) {
12736 		link_fd = -errno;
12737 		free(link);
12738 		pr_warn("prog '%s': failed to attach to %s: %s\n",
12739 			prog->name, target_name,
12740 			errstr(link_fd));
12741 		return libbpf_err_ptr(link_fd);
12742 	}
12743 	link->fd = link_fd;
12744 	return link;
12745 }
12746 
12747 struct bpf_link *
bpf_program__attach_cgroup(const struct bpf_program * prog,int cgroup_fd)12748 bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)
12749 {
12750 	return bpf_program_attach_fd(prog, cgroup_fd, "cgroup", NULL);
12751 }
12752 
12753 struct bpf_link *
bpf_program__attach_netns(const struct bpf_program * prog,int netns_fd)12754 bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)
12755 {
12756 	return bpf_program_attach_fd(prog, netns_fd, "netns", NULL);
12757 }
12758 
12759 struct bpf_link *
bpf_program__attach_sockmap(const struct bpf_program * prog,int map_fd)12760 bpf_program__attach_sockmap(const struct bpf_program *prog, int map_fd)
12761 {
12762 	return bpf_program_attach_fd(prog, map_fd, "sockmap", NULL);
12763 }
12764 
bpf_program__attach_xdp(const struct bpf_program * prog,int ifindex)12765 struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)
12766 {
12767 	/* target_fd/target_ifindex use the same field in LINK_CREATE */
12768 	return bpf_program_attach_fd(prog, ifindex, "xdp", NULL);
12769 }
12770 
12771 struct bpf_link *
bpf_program__attach_tcx(const struct bpf_program * prog,int ifindex,const struct bpf_tcx_opts * opts)12772 bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,
12773 			const struct bpf_tcx_opts *opts)
12774 {
12775 	LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
12776 	__u32 relative_id;
12777 	int relative_fd;
12778 
12779 	if (!OPTS_VALID(opts, bpf_tcx_opts))
12780 		return libbpf_err_ptr(-EINVAL);
12781 
12782 	relative_id = OPTS_GET(opts, relative_id, 0);
12783 	relative_fd = OPTS_GET(opts, relative_fd, 0);
12784 
12785 	/* validate we don't have unexpected combinations of non-zero fields */
12786 	if (!ifindex) {
12787 		pr_warn("prog '%s': target netdevice ifindex cannot be zero\n",
12788 			prog->name);
12789 		return libbpf_err_ptr(-EINVAL);
12790 	}
12791 	if (relative_fd && relative_id) {
12792 		pr_warn("prog '%s': relative_fd and relative_id cannot be set at the same time\n",
12793 			prog->name);
12794 		return libbpf_err_ptr(-EINVAL);
12795 	}
12796 
12797 	link_create_opts.tcx.expected_revision = OPTS_GET(opts, expected_revision, 0);
12798 	link_create_opts.tcx.relative_fd = relative_fd;
12799 	link_create_opts.tcx.relative_id = relative_id;
12800 	link_create_opts.flags = OPTS_GET(opts, flags, 0);
12801 
12802 	/* target_fd/target_ifindex use the same field in LINK_CREATE */
12803 	return bpf_program_attach_fd(prog, ifindex, "tcx", &link_create_opts);
12804 }
12805 
12806 struct bpf_link *
bpf_program__attach_netkit(const struct bpf_program * prog,int ifindex,const struct bpf_netkit_opts * opts)12807 bpf_program__attach_netkit(const struct bpf_program *prog, int ifindex,
12808 			   const struct bpf_netkit_opts *opts)
12809 {
12810 	LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
12811 	__u32 relative_id;
12812 	int relative_fd;
12813 
12814 	if (!OPTS_VALID(opts, bpf_netkit_opts))
12815 		return libbpf_err_ptr(-EINVAL);
12816 
12817 	relative_id = OPTS_GET(opts, relative_id, 0);
12818 	relative_fd = OPTS_GET(opts, relative_fd, 0);
12819 
12820 	/* validate we don't have unexpected combinations of non-zero fields */
12821 	if (!ifindex) {
12822 		pr_warn("prog '%s': target netdevice ifindex cannot be zero\n",
12823 			prog->name);
12824 		return libbpf_err_ptr(-EINVAL);
12825 	}
12826 	if (relative_fd && relative_id) {
12827 		pr_warn("prog '%s': relative_fd and relative_id cannot be set at the same time\n",
12828 			prog->name);
12829 		return libbpf_err_ptr(-EINVAL);
12830 	}
12831 
12832 	link_create_opts.netkit.expected_revision = OPTS_GET(opts, expected_revision, 0);
12833 	link_create_opts.netkit.relative_fd = relative_fd;
12834 	link_create_opts.netkit.relative_id = relative_id;
12835 	link_create_opts.flags = OPTS_GET(opts, flags, 0);
12836 
12837 	return bpf_program_attach_fd(prog, ifindex, "netkit", &link_create_opts);
12838 }
12839 
bpf_program__attach_freplace(const struct bpf_program * prog,int target_fd,const char * attach_func_name)12840 struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
12841 					      int target_fd,
12842 					      const char *attach_func_name)
12843 {
12844 	int btf_id;
12845 
12846 	if (!!target_fd != !!attach_func_name) {
12847 		pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
12848 			prog->name);
12849 		return libbpf_err_ptr(-EINVAL);
12850 	}
12851 
12852 	if (prog->type != BPF_PROG_TYPE_EXT) {
12853 		pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace\n",
12854 			prog->name);
12855 		return libbpf_err_ptr(-EINVAL);
12856 	}
12857 
12858 	if (target_fd) {
12859 		LIBBPF_OPTS(bpf_link_create_opts, target_opts);
12860 
12861 		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
12862 		if (btf_id < 0)
12863 			return libbpf_err_ptr(btf_id);
12864 
12865 		target_opts.target_btf_id = btf_id;
12866 
12867 		return bpf_program_attach_fd(prog, target_fd, "freplace",
12868 					     &target_opts);
12869 	} else {
12870 		/* no target, so use raw_tracepoint_open for compatibility
12871 		 * with old kernels
12872 		 */
12873 		return bpf_program__attach_trace(prog);
12874 	}
12875 }
12876 
12877 struct bpf_link *
bpf_program__attach_iter(const struct bpf_program * prog,const struct bpf_iter_attach_opts * opts)12878 bpf_program__attach_iter(const struct bpf_program *prog,
12879 			 const struct bpf_iter_attach_opts *opts)
12880 {
12881 	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
12882 	struct bpf_link *link;
12883 	int prog_fd, link_fd;
12884 	__u32 target_fd = 0;
12885 
12886 	if (!OPTS_VALID(opts, bpf_iter_attach_opts))
12887 		return libbpf_err_ptr(-EINVAL);
12888 
12889 	link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
12890 	link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
12891 
12892 	prog_fd = bpf_program__fd(prog);
12893 	if (prog_fd < 0) {
12894 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
12895 		return libbpf_err_ptr(-EINVAL);
12896 	}
12897 
12898 	link = calloc(1, sizeof(*link));
12899 	if (!link)
12900 		return libbpf_err_ptr(-ENOMEM);
12901 	link->detach = &bpf_link__detach_fd;
12902 
12903 	link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
12904 				  &link_create_opts);
12905 	if (link_fd < 0) {
12906 		link_fd = -errno;
12907 		free(link);
12908 		pr_warn("prog '%s': failed to attach to iterator: %s\n",
12909 			prog->name, errstr(link_fd));
12910 		return libbpf_err_ptr(link_fd);
12911 	}
12912 	link->fd = link_fd;
12913 	return link;
12914 }
12915 
attach_iter(const struct bpf_program * prog,long cookie,struct bpf_link ** link)12916 static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link)
12917 {
12918 	*link = bpf_program__attach_iter(prog, NULL);
12919 	return libbpf_get_error(*link);
12920 }
12921 
bpf_program__attach_netfilter(const struct bpf_program * prog,const struct bpf_netfilter_opts * opts)12922 struct bpf_link *bpf_program__attach_netfilter(const struct bpf_program *prog,
12923 					       const struct bpf_netfilter_opts *opts)
12924 {
12925 	LIBBPF_OPTS(bpf_link_create_opts, lopts);
12926 	struct bpf_link *link;
12927 	int prog_fd, link_fd;
12928 
12929 	if (!OPTS_VALID(opts, bpf_netfilter_opts))
12930 		return libbpf_err_ptr(-EINVAL);
12931 
12932 	prog_fd = bpf_program__fd(prog);
12933 	if (prog_fd < 0) {
12934 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
12935 		return libbpf_err_ptr(-EINVAL);
12936 	}
12937 
12938 	link = calloc(1, sizeof(*link));
12939 	if (!link)
12940 		return libbpf_err_ptr(-ENOMEM);
12941 
12942 	link->detach = &bpf_link__detach_fd;
12943 
12944 	lopts.netfilter.pf = OPTS_GET(opts, pf, 0);
12945 	lopts.netfilter.hooknum = OPTS_GET(opts, hooknum, 0);
12946 	lopts.netfilter.priority = OPTS_GET(opts, priority, 0);
12947 	lopts.netfilter.flags = OPTS_GET(opts, flags, 0);
12948 
12949 	link_fd = bpf_link_create(prog_fd, 0, BPF_NETFILTER, &lopts);
12950 	if (link_fd < 0) {
12951 		link_fd = -errno;
12952 		free(link);
12953 		pr_warn("prog '%s': failed to attach to netfilter: %s\n",
12954 			prog->name, errstr(link_fd));
12955 		return libbpf_err_ptr(link_fd);
12956 	}
12957 	link->fd = link_fd;
12958 
12959 	return link;
12960 }
12961 
bpf_program__attach(const struct bpf_program * prog)12962 struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
12963 {
12964 	struct bpf_link *link = NULL;
12965 	int err;
12966 
12967 	if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
12968 		return libbpf_err_ptr(-EOPNOTSUPP);
12969 
12970 	if (bpf_program__fd(prog) < 0) {
12971 		pr_warn("prog '%s': can't attach BPF program without FD (was it loaded?)\n",
12972 			prog->name);
12973 		return libbpf_err_ptr(-EINVAL);
12974 	}
12975 
12976 	err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, &link);
12977 	if (err)
12978 		return libbpf_err_ptr(err);
12979 
12980 	/* When calling bpf_program__attach() explicitly, auto-attach support
12981 	 * is expected to work, so NULL returned link is considered an error.
12982 	 * This is different for skeleton's attach, see comment in
12983 	 * bpf_object__attach_skeleton().
12984 	 */
12985 	if (!link)
12986 		return libbpf_err_ptr(-EOPNOTSUPP);
12987 
12988 	return link;
12989 }
12990 
12991 struct bpf_link_struct_ops {
12992 	struct bpf_link link;
12993 	int map_fd;
12994 };
12995 
bpf_link__detach_struct_ops(struct bpf_link * link)12996 static int bpf_link__detach_struct_ops(struct bpf_link *link)
12997 {
12998 	struct bpf_link_struct_ops *st_link;
12999 	__u32 zero = 0;
13000 
13001 	st_link = container_of(link, struct bpf_link_struct_ops, link);
13002 
13003 	if (st_link->map_fd < 0)
13004 		/* w/o a real link */
13005 		return bpf_map_delete_elem(link->fd, &zero);
13006 
13007 	return close(link->fd);
13008 }
13009 
bpf_map__attach_struct_ops(const struct bpf_map * map)13010 struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map)
13011 {
13012 	struct bpf_link_struct_ops *link;
13013 	__u32 zero = 0;
13014 	int err, fd;
13015 
13016 	if (!bpf_map__is_struct_ops(map)) {
13017 		pr_warn("map '%s': can't attach non-struct_ops map\n", map->name);
13018 		return libbpf_err_ptr(-EINVAL);
13019 	}
13020 
13021 	if (map->fd < 0) {
13022 		pr_warn("map '%s': can't attach BPF map without FD (was it created?)\n", map->name);
13023 		return libbpf_err_ptr(-EINVAL);
13024 	}
13025 
13026 	link = calloc(1, sizeof(*link));
13027 	if (!link)
13028 		return libbpf_err_ptr(-EINVAL);
13029 
13030 	/* kern_vdata should be prepared during the loading phase. */
13031 	err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0);
13032 	/* It can be EBUSY if the map has been used to create or
13033 	 * update a link before.  We don't allow updating the value of
13034 	 * a struct_ops once it is set.  That ensures that the value
13035 	 * never changed.  So, it is safe to skip EBUSY.
13036 	 */
13037 	if (err && (!(map->def.map_flags & BPF_F_LINK) || err != -EBUSY)) {
13038 		free(link);
13039 		return libbpf_err_ptr(err);
13040 	}
13041 
13042 	link->link.detach = bpf_link__detach_struct_ops;
13043 
13044 	if (!(map->def.map_flags & BPF_F_LINK)) {
13045 		/* w/o a real link */
13046 		link->link.fd = map->fd;
13047 		link->map_fd = -1;
13048 		return &link->link;
13049 	}
13050 
13051 	fd = bpf_link_create(map->fd, 0, BPF_STRUCT_OPS, NULL);
13052 	if (fd < 0) {
13053 		free(link);
13054 		return libbpf_err_ptr(fd);
13055 	}
13056 
13057 	link->link.fd = fd;
13058 	link->map_fd = map->fd;
13059 
13060 	return &link->link;
13061 }
13062 
13063 /*
13064  * Swap the back struct_ops of a link with a new struct_ops map.
13065  */
bpf_link__update_map(struct bpf_link * link,const struct bpf_map * map)13066 int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map)
13067 {
13068 	struct bpf_link_struct_ops *st_ops_link;
13069 	__u32 zero = 0;
13070 	int err;
13071 
13072 	if (!bpf_map__is_struct_ops(map))
13073 		return -EINVAL;
13074 
13075 	if (map->fd < 0) {
13076 		pr_warn("map '%s': can't use BPF map without FD (was it created?)\n", map->name);
13077 		return -EINVAL;
13078 	}
13079 
13080 	st_ops_link = container_of(link, struct bpf_link_struct_ops, link);
13081 	/* Ensure the type of a link is correct */
13082 	if (st_ops_link->map_fd < 0)
13083 		return -EINVAL;
13084 
13085 	err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0);
13086 	/* It can be EBUSY if the map has been used to create or
13087 	 * update a link before.  We don't allow updating the value of
13088 	 * a struct_ops once it is set.  That ensures that the value
13089 	 * never changed.  So, it is safe to skip EBUSY.
13090 	 */
13091 	if (err && err != -EBUSY)
13092 		return err;
13093 
13094 	err = bpf_link_update(link->fd, map->fd, NULL);
13095 	if (err < 0)
13096 		return err;
13097 
13098 	st_ops_link->map_fd = map->fd;
13099 
13100 	return 0;
13101 }
13102 
13103 typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr,
13104 							  void *private_data);
13105 
13106 static enum bpf_perf_event_ret
perf_event_read_simple(void * mmap_mem,size_t mmap_size,size_t page_size,void ** copy_mem,size_t * copy_size,bpf_perf_event_print_t fn,void * private_data)13107 perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
13108 		       void **copy_mem, size_t *copy_size,
13109 		       bpf_perf_event_print_t fn, void *private_data)
13110 {
13111 	struct perf_event_mmap_page *header = mmap_mem;
13112 	__u64 data_head = ring_buffer_read_head(header);
13113 	__u64 data_tail = header->data_tail;
13114 	void *base = ((__u8 *)header) + page_size;
13115 	int ret = LIBBPF_PERF_EVENT_CONT;
13116 	struct perf_event_header *ehdr;
13117 	size_t ehdr_size;
13118 
13119 	while (data_head != data_tail) {
13120 		ehdr = base + (data_tail & (mmap_size - 1));
13121 		ehdr_size = ehdr->size;
13122 
13123 		if (((void *)ehdr) + ehdr_size > base + mmap_size) {
13124 			void *copy_start = ehdr;
13125 			size_t len_first = base + mmap_size - copy_start;
13126 			size_t len_secnd = ehdr_size - len_first;
13127 
13128 			if (*copy_size < ehdr_size) {
13129 				free(*copy_mem);
13130 				*copy_mem = malloc(ehdr_size);
13131 				if (!*copy_mem) {
13132 					*copy_size = 0;
13133 					ret = LIBBPF_PERF_EVENT_ERROR;
13134 					break;
13135 				}
13136 				*copy_size = ehdr_size;
13137 			}
13138 
13139 			memcpy(*copy_mem, copy_start, len_first);
13140 			memcpy(*copy_mem + len_first, base, len_secnd);
13141 			ehdr = *copy_mem;
13142 		}
13143 
13144 		ret = fn(ehdr, private_data);
13145 		data_tail += ehdr_size;
13146 		if (ret != LIBBPF_PERF_EVENT_CONT)
13147 			break;
13148 	}
13149 
13150 	ring_buffer_write_tail(header, data_tail);
13151 	return libbpf_err(ret);
13152 }
13153 
13154 struct perf_buffer;
13155 
13156 struct perf_buffer_params {
13157 	struct perf_event_attr *attr;
13158 	/* if event_cb is specified, it takes precendence */
13159 	perf_buffer_event_fn event_cb;
13160 	/* sample_cb and lost_cb are higher-level common-case callbacks */
13161 	perf_buffer_sample_fn sample_cb;
13162 	perf_buffer_lost_fn lost_cb;
13163 	void *ctx;
13164 	int cpu_cnt;
13165 	int *cpus;
13166 	int *map_keys;
13167 };
13168 
13169 struct perf_cpu_buf {
13170 	struct perf_buffer *pb;
13171 	void *base; /* mmap()'ed memory */
13172 	void *buf; /* for reconstructing segmented data */
13173 	size_t buf_size;
13174 	int fd;
13175 	int cpu;
13176 	int map_key;
13177 };
13178 
13179 struct perf_buffer {
13180 	perf_buffer_event_fn event_cb;
13181 	perf_buffer_sample_fn sample_cb;
13182 	perf_buffer_lost_fn lost_cb;
13183 	void *ctx; /* passed into callbacks */
13184 
13185 	size_t page_size;
13186 	size_t mmap_size;
13187 	struct perf_cpu_buf **cpu_bufs;
13188 	struct epoll_event *events;
13189 	int cpu_cnt; /* number of allocated CPU buffers */
13190 	int epoll_fd; /* perf event FD */
13191 	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
13192 };
13193 
perf_buffer__free_cpu_buf(struct perf_buffer * pb,struct perf_cpu_buf * cpu_buf)13194 static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
13195 				      struct perf_cpu_buf *cpu_buf)
13196 {
13197 	if (!cpu_buf)
13198 		return;
13199 	if (cpu_buf->base &&
13200 	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
13201 		pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
13202 	if (cpu_buf->fd >= 0) {
13203 		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
13204 		close(cpu_buf->fd);
13205 	}
13206 	free(cpu_buf->buf);
13207 	free(cpu_buf);
13208 }
13209 
perf_buffer__free(struct perf_buffer * pb)13210 void perf_buffer__free(struct perf_buffer *pb)
13211 {
13212 	int i;
13213 
13214 	if (IS_ERR_OR_NULL(pb))
13215 		return;
13216 	if (pb->cpu_bufs) {
13217 		for (i = 0; i < pb->cpu_cnt; i++) {
13218 			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
13219 
13220 			if (!cpu_buf)
13221 				continue;
13222 
13223 			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
13224 			perf_buffer__free_cpu_buf(pb, cpu_buf);
13225 		}
13226 		free(pb->cpu_bufs);
13227 	}
13228 	if (pb->epoll_fd >= 0)
13229 		close(pb->epoll_fd);
13230 	free(pb->events);
13231 	free(pb);
13232 }
13233 
13234 static struct perf_cpu_buf *
perf_buffer__open_cpu_buf(struct perf_buffer * pb,struct perf_event_attr * attr,int cpu,int map_key)13235 perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
13236 			  int cpu, int map_key)
13237 {
13238 	struct perf_cpu_buf *cpu_buf;
13239 	int err;
13240 
13241 	cpu_buf = calloc(1, sizeof(*cpu_buf));
13242 	if (!cpu_buf)
13243 		return ERR_PTR(-ENOMEM);
13244 
13245 	cpu_buf->pb = pb;
13246 	cpu_buf->cpu = cpu;
13247 	cpu_buf->map_key = map_key;
13248 
13249 	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
13250 			      -1, PERF_FLAG_FD_CLOEXEC);
13251 	if (cpu_buf->fd < 0) {
13252 		err = -errno;
13253 		pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
13254 			cpu, errstr(err));
13255 		goto error;
13256 	}
13257 
13258 	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
13259 			     PROT_READ | PROT_WRITE, MAP_SHARED,
13260 			     cpu_buf->fd, 0);
13261 	if (cpu_buf->base == MAP_FAILED) {
13262 		cpu_buf->base = NULL;
13263 		err = -errno;
13264 		pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
13265 			cpu, errstr(err));
13266 		goto error;
13267 	}
13268 
13269 	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
13270 		err = -errno;
13271 		pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
13272 			cpu, errstr(err));
13273 		goto error;
13274 	}
13275 
13276 	return cpu_buf;
13277 
13278 error:
13279 	perf_buffer__free_cpu_buf(pb, cpu_buf);
13280 	return (struct perf_cpu_buf *)ERR_PTR(err);
13281 }
13282 
13283 static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
13284 					      struct perf_buffer_params *p);
13285 
perf_buffer__new(int map_fd,size_t page_cnt,perf_buffer_sample_fn sample_cb,perf_buffer_lost_fn lost_cb,void * ctx,const struct perf_buffer_opts * opts)13286 struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
13287 				     perf_buffer_sample_fn sample_cb,
13288 				     perf_buffer_lost_fn lost_cb,
13289 				     void *ctx,
13290 				     const struct perf_buffer_opts *opts)
13291 {
13292 	const size_t attr_sz = sizeof(struct perf_event_attr);
13293 	struct perf_buffer_params p = {};
13294 	struct perf_event_attr attr;
13295 	__u32 sample_period;
13296 
13297 	if (!OPTS_VALID(opts, perf_buffer_opts))
13298 		return libbpf_err_ptr(-EINVAL);
13299 
13300 	sample_period = OPTS_GET(opts, sample_period, 1);
13301 	if (!sample_period)
13302 		sample_period = 1;
13303 
13304 	memset(&attr, 0, attr_sz);
13305 	attr.size = attr_sz;
13306 	attr.config = PERF_COUNT_SW_BPF_OUTPUT;
13307 	attr.type = PERF_TYPE_SOFTWARE;
13308 	attr.sample_type = PERF_SAMPLE_RAW;
13309 	attr.sample_period = sample_period;
13310 	attr.wakeup_events = sample_period;
13311 
13312 	p.attr = &attr;
13313 	p.sample_cb = sample_cb;
13314 	p.lost_cb = lost_cb;
13315 	p.ctx = ctx;
13316 
13317 	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
13318 }
13319 
perf_buffer__new_raw(int map_fd,size_t page_cnt,struct perf_event_attr * attr,perf_buffer_event_fn event_cb,void * ctx,const struct perf_buffer_raw_opts * opts)13320 struct perf_buffer *perf_buffer__new_raw(int map_fd, size_t page_cnt,
13321 					 struct perf_event_attr *attr,
13322 					 perf_buffer_event_fn event_cb, void *ctx,
13323 					 const struct perf_buffer_raw_opts *opts)
13324 {
13325 	struct perf_buffer_params p = {};
13326 
13327 	if (!attr)
13328 		return libbpf_err_ptr(-EINVAL);
13329 
13330 	if (!OPTS_VALID(opts, perf_buffer_raw_opts))
13331 		return libbpf_err_ptr(-EINVAL);
13332 
13333 	p.attr = attr;
13334 	p.event_cb = event_cb;
13335 	p.ctx = ctx;
13336 	p.cpu_cnt = OPTS_GET(opts, cpu_cnt, 0);
13337 	p.cpus = OPTS_GET(opts, cpus, NULL);
13338 	p.map_keys = OPTS_GET(opts, map_keys, NULL);
13339 
13340 	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
13341 }
13342 
__perf_buffer__new(int map_fd,size_t page_cnt,struct perf_buffer_params * p)13343 static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
13344 					      struct perf_buffer_params *p)
13345 {
13346 	const char *online_cpus_file = "/sys/devices/system/cpu/online";
13347 	struct bpf_map_info map;
13348 	struct perf_buffer *pb;
13349 	bool *online = NULL;
13350 	__u32 map_info_len;
13351 	int err, i, j, n;
13352 
13353 	if (page_cnt == 0 || (page_cnt & (page_cnt - 1))) {
13354 		pr_warn("page count should be power of two, but is %zu\n",
13355 			page_cnt);
13356 		return ERR_PTR(-EINVAL);
13357 	}
13358 
13359 	/* best-effort sanity checks */
13360 	memset(&map, 0, sizeof(map));
13361 	map_info_len = sizeof(map);
13362 	err = bpf_map_get_info_by_fd(map_fd, &map, &map_info_len);
13363 	if (err) {
13364 		err = -errno;
13365 		/* if BPF_OBJ_GET_INFO_BY_FD is supported, will return
13366 		 * -EBADFD, -EFAULT, or -E2BIG on real error
13367 		 */
13368 		if (err != -EINVAL) {
13369 			pr_warn("failed to get map info for map FD %d: %s\n",
13370 				map_fd, errstr(err));
13371 			return ERR_PTR(err);
13372 		}
13373 		pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n",
13374 			 map_fd);
13375 	} else {
13376 		if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
13377 			pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
13378 				map.name);
13379 			return ERR_PTR(-EINVAL);
13380 		}
13381 	}
13382 
13383 	pb = calloc(1, sizeof(*pb));
13384 	if (!pb)
13385 		return ERR_PTR(-ENOMEM);
13386 
13387 	pb->event_cb = p->event_cb;
13388 	pb->sample_cb = p->sample_cb;
13389 	pb->lost_cb = p->lost_cb;
13390 	pb->ctx = p->ctx;
13391 
13392 	pb->page_size = getpagesize();
13393 	pb->mmap_size = pb->page_size * page_cnt;
13394 	pb->map_fd = map_fd;
13395 
13396 	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
13397 	if (pb->epoll_fd < 0) {
13398 		err = -errno;
13399 		pr_warn("failed to create epoll instance: %s\n",
13400 			errstr(err));
13401 		goto error;
13402 	}
13403 
13404 	if (p->cpu_cnt > 0) {
13405 		pb->cpu_cnt = p->cpu_cnt;
13406 	} else {
13407 		pb->cpu_cnt = libbpf_num_possible_cpus();
13408 		if (pb->cpu_cnt < 0) {
13409 			err = pb->cpu_cnt;
13410 			goto error;
13411 		}
13412 		if (map.max_entries && map.max_entries < pb->cpu_cnt)
13413 			pb->cpu_cnt = map.max_entries;
13414 	}
13415 
13416 	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
13417 	if (!pb->events) {
13418 		err = -ENOMEM;
13419 		pr_warn("failed to allocate events: out of memory\n");
13420 		goto error;
13421 	}
13422 	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
13423 	if (!pb->cpu_bufs) {
13424 		err = -ENOMEM;
13425 		pr_warn("failed to allocate buffers: out of memory\n");
13426 		goto error;
13427 	}
13428 
13429 	err = parse_cpu_mask_file(online_cpus_file, &online, &n);
13430 	if (err) {
13431 		pr_warn("failed to get online CPU mask: %s\n", errstr(err));
13432 		goto error;
13433 	}
13434 
13435 	for (i = 0, j = 0; i < pb->cpu_cnt; i++) {
13436 		struct perf_cpu_buf *cpu_buf;
13437 		int cpu, map_key;
13438 
13439 		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
13440 		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
13441 
13442 		/* in case user didn't explicitly requested particular CPUs to
13443 		 * be attached to, skip offline/not present CPUs
13444 		 */
13445 		if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu]))
13446 			continue;
13447 
13448 		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
13449 		if (IS_ERR(cpu_buf)) {
13450 			err = PTR_ERR(cpu_buf);
13451 			goto error;
13452 		}
13453 
13454 		pb->cpu_bufs[j] = cpu_buf;
13455 
13456 		err = bpf_map_update_elem(pb->map_fd, &map_key,
13457 					  &cpu_buf->fd, 0);
13458 		if (err) {
13459 			err = -errno;
13460 			pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
13461 				cpu, map_key, cpu_buf->fd,
13462 				errstr(err));
13463 			goto error;
13464 		}
13465 
13466 		pb->events[j].events = EPOLLIN;
13467 		pb->events[j].data.ptr = cpu_buf;
13468 		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
13469 			      &pb->events[j]) < 0) {
13470 			err = -errno;
13471 			pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
13472 				cpu, cpu_buf->fd,
13473 				errstr(err));
13474 			goto error;
13475 		}
13476 		j++;
13477 	}
13478 	pb->cpu_cnt = j;
13479 	free(online);
13480 
13481 	return pb;
13482 
13483 error:
13484 	free(online);
13485 	if (pb)
13486 		perf_buffer__free(pb);
13487 	return ERR_PTR(err);
13488 }
13489 
13490 struct perf_sample_raw {
13491 	struct perf_event_header header;
13492 	uint32_t size;
13493 	char data[];
13494 };
13495 
13496 struct perf_sample_lost {
13497 	struct perf_event_header header;
13498 	uint64_t id;
13499 	uint64_t lost;
13500 	uint64_t sample_id;
13501 };
13502 
13503 static enum bpf_perf_event_ret
perf_buffer__process_record(struct perf_event_header * e,void * ctx)13504 perf_buffer__process_record(struct perf_event_header *e, void *ctx)
13505 {
13506 	struct perf_cpu_buf *cpu_buf = ctx;
13507 	struct perf_buffer *pb = cpu_buf->pb;
13508 	void *data = e;
13509 
13510 	/* user wants full control over parsing perf event */
13511 	if (pb->event_cb)
13512 		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
13513 
13514 	switch (e->type) {
13515 	case PERF_RECORD_SAMPLE: {
13516 		struct perf_sample_raw *s = data;
13517 
13518 		if (pb->sample_cb)
13519 			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
13520 		break;
13521 	}
13522 	case PERF_RECORD_LOST: {
13523 		struct perf_sample_lost *s = data;
13524 
13525 		if (pb->lost_cb)
13526 			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
13527 		break;
13528 	}
13529 	default:
13530 		pr_warn("unknown perf sample type %d\n", e->type);
13531 		return LIBBPF_PERF_EVENT_ERROR;
13532 	}
13533 	return LIBBPF_PERF_EVENT_CONT;
13534 }
13535 
perf_buffer__process_records(struct perf_buffer * pb,struct perf_cpu_buf * cpu_buf)13536 static int perf_buffer__process_records(struct perf_buffer *pb,
13537 					struct perf_cpu_buf *cpu_buf)
13538 {
13539 	enum bpf_perf_event_ret ret;
13540 
13541 	ret = perf_event_read_simple(cpu_buf->base, pb->mmap_size,
13542 				     pb->page_size, &cpu_buf->buf,
13543 				     &cpu_buf->buf_size,
13544 				     perf_buffer__process_record, cpu_buf);
13545 	if (ret != LIBBPF_PERF_EVENT_CONT)
13546 		return ret;
13547 	return 0;
13548 }
13549 
perf_buffer__epoll_fd(const struct perf_buffer * pb)13550 int perf_buffer__epoll_fd(const struct perf_buffer *pb)
13551 {
13552 	return pb->epoll_fd;
13553 }
13554 
perf_buffer__poll(struct perf_buffer * pb,int timeout_ms)13555 int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
13556 {
13557 	int i, cnt, err;
13558 
13559 	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
13560 	if (cnt < 0)
13561 		return -errno;
13562 
13563 	for (i = 0; i < cnt; i++) {
13564 		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
13565 
13566 		err = perf_buffer__process_records(pb, cpu_buf);
13567 		if (err) {
13568 			pr_warn("error while processing records: %s\n", errstr(err));
13569 			return libbpf_err(err);
13570 		}
13571 	}
13572 	return cnt;
13573 }
13574 
13575 /* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
13576  * manager.
13577  */
perf_buffer__buffer_cnt(const struct perf_buffer * pb)13578 size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb)
13579 {
13580 	return pb->cpu_cnt;
13581 }
13582 
13583 /*
13584  * Return perf_event FD of a ring buffer in *buf_idx* slot of
13585  * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using
13586  * select()/poll()/epoll() Linux syscalls.
13587  */
perf_buffer__buffer_fd(const struct perf_buffer * pb,size_t buf_idx)13588 int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx)
13589 {
13590 	struct perf_cpu_buf *cpu_buf;
13591 
13592 	if (buf_idx >= pb->cpu_cnt)
13593 		return libbpf_err(-EINVAL);
13594 
13595 	cpu_buf = pb->cpu_bufs[buf_idx];
13596 	if (!cpu_buf)
13597 		return libbpf_err(-ENOENT);
13598 
13599 	return cpu_buf->fd;
13600 }
13601 
perf_buffer__buffer(struct perf_buffer * pb,int buf_idx,void ** buf,size_t * buf_size)13602 int perf_buffer__buffer(struct perf_buffer *pb, int buf_idx, void **buf, size_t *buf_size)
13603 {
13604 	struct perf_cpu_buf *cpu_buf;
13605 
13606 	if (buf_idx >= pb->cpu_cnt)
13607 		return libbpf_err(-EINVAL);
13608 
13609 	cpu_buf = pb->cpu_bufs[buf_idx];
13610 	if (!cpu_buf)
13611 		return libbpf_err(-ENOENT);
13612 
13613 	*buf = cpu_buf->base;
13614 	*buf_size = pb->mmap_size;
13615 	return 0;
13616 }
13617 
13618 /*
13619  * Consume data from perf ring buffer corresponding to slot *buf_idx* in
13620  * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to
13621  * consume, do nothing and return success.
13622  * Returns:
13623  *   - 0 on success;
13624  *   - <0 on failure.
13625  */
perf_buffer__consume_buffer(struct perf_buffer * pb,size_t buf_idx)13626 int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx)
13627 {
13628 	struct perf_cpu_buf *cpu_buf;
13629 
13630 	if (buf_idx >= pb->cpu_cnt)
13631 		return libbpf_err(-EINVAL);
13632 
13633 	cpu_buf = pb->cpu_bufs[buf_idx];
13634 	if (!cpu_buf)
13635 		return libbpf_err(-ENOENT);
13636 
13637 	return perf_buffer__process_records(pb, cpu_buf);
13638 }
13639 
perf_buffer__consume(struct perf_buffer * pb)13640 int perf_buffer__consume(struct perf_buffer *pb)
13641 {
13642 	int i, err;
13643 
13644 	for (i = 0; i < pb->cpu_cnt; i++) {
13645 		struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
13646 
13647 		if (!cpu_buf)
13648 			continue;
13649 
13650 		err = perf_buffer__process_records(pb, cpu_buf);
13651 		if (err) {
13652 			pr_warn("perf_buffer: failed to process records in buffer #%d: %s\n",
13653 				i, errstr(err));
13654 			return libbpf_err(err);
13655 		}
13656 	}
13657 	return 0;
13658 }
13659 
bpf_program__set_attach_target(struct bpf_program * prog,int attach_prog_fd,const char * attach_func_name)13660 int bpf_program__set_attach_target(struct bpf_program *prog,
13661 				   int attach_prog_fd,
13662 				   const char *attach_func_name)
13663 {
13664 	int btf_obj_fd = 0, btf_id = 0, err;
13665 
13666 	if (!prog || attach_prog_fd < 0)
13667 		return libbpf_err(-EINVAL);
13668 
13669 	if (prog->obj->loaded)
13670 		return libbpf_err(-EINVAL);
13671 
13672 	if (attach_prog_fd && !attach_func_name) {
13673 		/* remember attach_prog_fd and let bpf_program__load() find
13674 		 * BTF ID during the program load
13675 		 */
13676 		prog->attach_prog_fd = attach_prog_fd;
13677 		return 0;
13678 	}
13679 
13680 	if (attach_prog_fd) {
13681 		btf_id = libbpf_find_prog_btf_id(attach_func_name,
13682 						 attach_prog_fd);
13683 		if (btf_id < 0)
13684 			return libbpf_err(btf_id);
13685 	} else {
13686 		if (!attach_func_name)
13687 			return libbpf_err(-EINVAL);
13688 
13689 		/* load btf_vmlinux, if not yet */
13690 		err = bpf_object__load_vmlinux_btf(prog->obj, true);
13691 		if (err)
13692 			return libbpf_err(err);
13693 		err = find_kernel_btf_id(prog->obj, attach_func_name,
13694 					 prog->expected_attach_type,
13695 					 &btf_obj_fd, &btf_id);
13696 		if (err)
13697 			return libbpf_err(err);
13698 	}
13699 
13700 	prog->attach_btf_id = btf_id;
13701 	prog->attach_btf_obj_fd = btf_obj_fd;
13702 	prog->attach_prog_fd = attach_prog_fd;
13703 	return 0;
13704 }
13705 
parse_cpu_mask_str(const char * s,bool ** mask,int * mask_sz)13706 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
13707 {
13708 	int err = 0, n, len, start, end = -1;
13709 	bool *tmp;
13710 
13711 	*mask = NULL;
13712 	*mask_sz = 0;
13713 
13714 	/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
13715 	while (*s) {
13716 		if (*s == ',' || *s == '\n') {
13717 			s++;
13718 			continue;
13719 		}
13720 		n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len);
13721 		if (n <= 0 || n > 2) {
13722 			pr_warn("Failed to get CPU range %s: %d\n", s, n);
13723 			err = -EINVAL;
13724 			goto cleanup;
13725 		} else if (n == 1) {
13726 			end = start;
13727 		}
13728 		if (start < 0 || start > end) {
13729 			pr_warn("Invalid CPU range [%d,%d] in %s\n",
13730 				start, end, s);
13731 			err = -EINVAL;
13732 			goto cleanup;
13733 		}
13734 		tmp = realloc(*mask, end + 1);
13735 		if (!tmp) {
13736 			err = -ENOMEM;
13737 			goto cleanup;
13738 		}
13739 		*mask = tmp;
13740 		memset(tmp + *mask_sz, 0, start - *mask_sz);
13741 		memset(tmp + start, 1, end - start + 1);
13742 		*mask_sz = end + 1;
13743 		s += len;
13744 	}
13745 	if (!*mask_sz) {
13746 		pr_warn("Empty CPU range\n");
13747 		return -EINVAL;
13748 	}
13749 	return 0;
13750 cleanup:
13751 	free(*mask);
13752 	*mask = NULL;
13753 	return err;
13754 }
13755 
parse_cpu_mask_file(const char * fcpu,bool ** mask,int * mask_sz)13756 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz)
13757 {
13758 	int fd, err = 0, len;
13759 	char buf[128];
13760 
13761 	fd = open(fcpu, O_RDONLY | O_CLOEXEC);
13762 	if (fd < 0) {
13763 		err = -errno;
13764 		pr_warn("Failed to open cpu mask file %s: %s\n", fcpu, errstr(err));
13765 		return err;
13766 	}
13767 	len = read(fd, buf, sizeof(buf));
13768 	close(fd);
13769 	if (len <= 0) {
13770 		err = len ? -errno : -EINVAL;
13771 		pr_warn("Failed to read cpu mask from %s: %s\n", fcpu, errstr(err));
13772 		return err;
13773 	}
13774 	if (len >= sizeof(buf)) {
13775 		pr_warn("CPU mask is too big in file %s\n", fcpu);
13776 		return -E2BIG;
13777 	}
13778 	buf[len] = '\0';
13779 
13780 	return parse_cpu_mask_str(buf, mask, mask_sz);
13781 }
13782 
libbpf_num_possible_cpus(void)13783 int libbpf_num_possible_cpus(void)
13784 {
13785 	static const char *fcpu = "/sys/devices/system/cpu/possible";
13786 	static int cpus;
13787 	int err, n, i, tmp_cpus;
13788 	bool *mask;
13789 
13790 	tmp_cpus = READ_ONCE(cpus);
13791 	if (tmp_cpus > 0)
13792 		return tmp_cpus;
13793 
13794 	err = parse_cpu_mask_file(fcpu, &mask, &n);
13795 	if (err)
13796 		return libbpf_err(err);
13797 
13798 	tmp_cpus = 0;
13799 	for (i = 0; i < n; i++) {
13800 		if (mask[i])
13801 			tmp_cpus++;
13802 	}
13803 	free(mask);
13804 
13805 	WRITE_ONCE(cpus, tmp_cpus);
13806 	return tmp_cpus;
13807 }
13808 
populate_skeleton_maps(const struct bpf_object * obj,struct bpf_map_skeleton * maps,size_t map_cnt,size_t map_skel_sz)13809 static int populate_skeleton_maps(const struct bpf_object *obj,
13810 				  struct bpf_map_skeleton *maps,
13811 				  size_t map_cnt, size_t map_skel_sz)
13812 {
13813 	int i;
13814 
13815 	for (i = 0; i < map_cnt; i++) {
13816 		struct bpf_map_skeleton *map_skel = (void *)maps + i * map_skel_sz;
13817 		struct bpf_map **map = map_skel->map;
13818 		const char *name = map_skel->name;
13819 		void **mmaped = map_skel->mmaped;
13820 
13821 		*map = bpf_object__find_map_by_name(obj, name);
13822 		if (!*map) {
13823 			pr_warn("failed to find skeleton map '%s'\n", name);
13824 			return -ESRCH;
13825 		}
13826 
13827 		/* externs shouldn't be pre-setup from user code */
13828 		if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)
13829 			*mmaped = (*map)->mmaped;
13830 	}
13831 	return 0;
13832 }
13833 
populate_skeleton_progs(const struct bpf_object * obj,struct bpf_prog_skeleton * progs,size_t prog_cnt,size_t prog_skel_sz)13834 static int populate_skeleton_progs(const struct bpf_object *obj,
13835 				   struct bpf_prog_skeleton *progs,
13836 				   size_t prog_cnt, size_t prog_skel_sz)
13837 {
13838 	int i;
13839 
13840 	for (i = 0; i < prog_cnt; i++) {
13841 		struct bpf_prog_skeleton *prog_skel = (void *)progs + i * prog_skel_sz;
13842 		struct bpf_program **prog = prog_skel->prog;
13843 		const char *name = prog_skel->name;
13844 
13845 		*prog = bpf_object__find_program_by_name(obj, name);
13846 		if (!*prog) {
13847 			pr_warn("failed to find skeleton program '%s'\n", name);
13848 			return -ESRCH;
13849 		}
13850 	}
13851 	return 0;
13852 }
13853 
bpf_object__open_skeleton(struct bpf_object_skeleton * s,const struct bpf_object_open_opts * opts)13854 int bpf_object__open_skeleton(struct bpf_object_skeleton *s,
13855 			      const struct bpf_object_open_opts *opts)
13856 {
13857 	struct bpf_object *obj;
13858 	int err;
13859 
13860 	obj = bpf_object_open(NULL, s->data, s->data_sz, s->name, opts);
13861 	if (IS_ERR(obj)) {
13862 		err = PTR_ERR(obj);
13863 		pr_warn("failed to initialize skeleton BPF object '%s': %s\n",
13864 			s->name, errstr(err));
13865 		return libbpf_err(err);
13866 	}
13867 
13868 	*s->obj = obj;
13869 	err = populate_skeleton_maps(obj, s->maps, s->map_cnt, s->map_skel_sz);
13870 	if (err) {
13871 		pr_warn("failed to populate skeleton maps for '%s': %s\n", s->name, errstr(err));
13872 		return libbpf_err(err);
13873 	}
13874 
13875 	err = populate_skeleton_progs(obj, s->progs, s->prog_cnt, s->prog_skel_sz);
13876 	if (err) {
13877 		pr_warn("failed to populate skeleton progs for '%s': %s\n", s->name, errstr(err));
13878 		return libbpf_err(err);
13879 	}
13880 
13881 	return 0;
13882 }
13883 
bpf_object__open_subskeleton(struct bpf_object_subskeleton * s)13884 int bpf_object__open_subskeleton(struct bpf_object_subskeleton *s)
13885 {
13886 	int err, len, var_idx, i;
13887 	const char *var_name;
13888 	const struct bpf_map *map;
13889 	struct btf *btf;
13890 	__u32 map_type_id;
13891 	const struct btf_type *map_type, *var_type;
13892 	const struct bpf_var_skeleton *var_skel;
13893 	struct btf_var_secinfo *var;
13894 
13895 	if (!s->obj)
13896 		return libbpf_err(-EINVAL);
13897 
13898 	btf = bpf_object__btf(s->obj);
13899 	if (!btf) {
13900 		pr_warn("subskeletons require BTF at runtime (object %s)\n",
13901 			bpf_object__name(s->obj));
13902 		return libbpf_err(-errno);
13903 	}
13904 
13905 	err = populate_skeleton_maps(s->obj, s->maps, s->map_cnt, s->map_skel_sz);
13906 	if (err) {
13907 		pr_warn("failed to populate subskeleton maps: %s\n", errstr(err));
13908 		return libbpf_err(err);
13909 	}
13910 
13911 	err = populate_skeleton_progs(s->obj, s->progs, s->prog_cnt, s->prog_skel_sz);
13912 	if (err) {
13913 		pr_warn("failed to populate subskeleton maps: %s\n", errstr(err));
13914 		return libbpf_err(err);
13915 	}
13916 
13917 	for (var_idx = 0; var_idx < s->var_cnt; var_idx++) {
13918 		var_skel = (void *)s->vars + var_idx * s->var_skel_sz;
13919 		map = *var_skel->map;
13920 		map_type_id = bpf_map__btf_value_type_id(map);
13921 		map_type = btf__type_by_id(btf, map_type_id);
13922 
13923 		if (!btf_is_datasec(map_type)) {
13924 			pr_warn("type for map '%1$s' is not a datasec: %2$s\n",
13925 				bpf_map__name(map),
13926 				__btf_kind_str(btf_kind(map_type)));
13927 			return libbpf_err(-EINVAL);
13928 		}
13929 
13930 		len = btf_vlen(map_type);
13931 		var = btf_var_secinfos(map_type);
13932 		for (i = 0; i < len; i++, var++) {
13933 			var_type = btf__type_by_id(btf, var->type);
13934 			var_name = btf__name_by_offset(btf, var_type->name_off);
13935 			if (strcmp(var_name, var_skel->name) == 0) {
13936 				*var_skel->addr = map->mmaped + var->offset;
13937 				break;
13938 			}
13939 		}
13940 	}
13941 	return 0;
13942 }
13943 
bpf_object__destroy_subskeleton(struct bpf_object_subskeleton * s)13944 void bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s)
13945 {
13946 	if (!s)
13947 		return;
13948 	free(s->maps);
13949 	free(s->progs);
13950 	free(s->vars);
13951 	free(s);
13952 }
13953 
bpf_object__load_skeleton(struct bpf_object_skeleton * s)13954 int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
13955 {
13956 	int i, err;
13957 
13958 	err = bpf_object__load(*s->obj);
13959 	if (err) {
13960 		pr_warn("failed to load BPF skeleton '%s': %s\n", s->name, errstr(err));
13961 		return libbpf_err(err);
13962 	}
13963 
13964 	for (i = 0; i < s->map_cnt; i++) {
13965 		struct bpf_map_skeleton *map_skel = (void *)s->maps + i * s->map_skel_sz;
13966 		struct bpf_map *map = *map_skel->map;
13967 
13968 		if (!map_skel->mmaped)
13969 			continue;
13970 
13971 		*map_skel->mmaped = map->mmaped;
13972 	}
13973 
13974 	return 0;
13975 }
13976 
bpf_object__attach_skeleton(struct bpf_object_skeleton * s)13977 int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
13978 {
13979 	int i, err;
13980 
13981 	for (i = 0; i < s->prog_cnt; i++) {
13982 		struct bpf_prog_skeleton *prog_skel = (void *)s->progs + i * s->prog_skel_sz;
13983 		struct bpf_program *prog = *prog_skel->prog;
13984 		struct bpf_link **link = prog_skel->link;
13985 
13986 		if (!prog->autoload || !prog->autoattach)
13987 			continue;
13988 
13989 		/* auto-attaching not supported for this program */
13990 		if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
13991 			continue;
13992 
13993 		/* if user already set the link manually, don't attempt auto-attach */
13994 		if (*link)
13995 			continue;
13996 
13997 		err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, link);
13998 		if (err) {
13999 			pr_warn("prog '%s': failed to auto-attach: %s\n",
14000 				bpf_program__name(prog), errstr(err));
14001 			return libbpf_err(err);
14002 		}
14003 
14004 		/* It's possible that for some SEC() definitions auto-attach
14005 		 * is supported in some cases (e.g., if definition completely
14006 		 * specifies target information), but is not in other cases.
14007 		 * SEC("uprobe") is one such case. If user specified target
14008 		 * binary and function name, such BPF program can be
14009 		 * auto-attached. But if not, it shouldn't trigger skeleton's
14010 		 * attach to fail. It should just be skipped.
14011 		 * attach_fn signals such case with returning 0 (no error) and
14012 		 * setting link to NULL.
14013 		 */
14014 	}
14015 
14016 
14017 	for (i = 0; i < s->map_cnt; i++) {
14018 		struct bpf_map_skeleton *map_skel = (void *)s->maps + i * s->map_skel_sz;
14019 		struct bpf_map *map = *map_skel->map;
14020 		struct bpf_link **link;
14021 
14022 		if (!map->autocreate || !map->autoattach)
14023 			continue;
14024 
14025 		/* only struct_ops maps can be attached */
14026 		if (!bpf_map__is_struct_ops(map))
14027 			continue;
14028 
14029 		/* skeleton is created with earlier version of bpftool, notify user */
14030 		if (s->map_skel_sz < offsetofend(struct bpf_map_skeleton, link)) {
14031 			pr_warn("map '%s': BPF skeleton version is old, skipping map auto-attachment...\n",
14032 				bpf_map__name(map));
14033 			continue;
14034 		}
14035 
14036 		link = map_skel->link;
14037 		if (*link)
14038 			continue;
14039 
14040 		*link = bpf_map__attach_struct_ops(map);
14041 		if (!*link) {
14042 			err = -errno;
14043 			pr_warn("map '%s': failed to auto-attach: %s\n",
14044 				bpf_map__name(map), errstr(err));
14045 			return libbpf_err(err);
14046 		}
14047 	}
14048 
14049 	return 0;
14050 }
14051 
bpf_object__detach_skeleton(struct bpf_object_skeleton * s)14052 void bpf_object__detach_skeleton(struct bpf_object_skeleton *s)
14053 {
14054 	int i;
14055 
14056 	for (i = 0; i < s->prog_cnt; i++) {
14057 		struct bpf_prog_skeleton *prog_skel = (void *)s->progs + i * s->prog_skel_sz;
14058 		struct bpf_link **link = prog_skel->link;
14059 
14060 		bpf_link__destroy(*link);
14061 		*link = NULL;
14062 	}
14063 
14064 	if (s->map_skel_sz < sizeof(struct bpf_map_skeleton))
14065 		return;
14066 
14067 	for (i = 0; i < s->map_cnt; i++) {
14068 		struct bpf_map_skeleton *map_skel = (void *)s->maps + i * s->map_skel_sz;
14069 		struct bpf_link **link = map_skel->link;
14070 
14071 		if (link) {
14072 			bpf_link__destroy(*link);
14073 			*link = NULL;
14074 		}
14075 	}
14076 }
14077 
bpf_object__destroy_skeleton(struct bpf_object_skeleton * s)14078 void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
14079 {
14080 	if (!s)
14081 		return;
14082 
14083 	bpf_object__detach_skeleton(s);
14084 	if (s->obj)
14085 		bpf_object__close(*s->obj);
14086 	free(s->maps);
14087 	free(s->progs);
14088 	free(s);
14089 }
14090