1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022, Oracle and/or its affiliates. */
3
4 #include <test_progs.h>
5 #include <bpf/btf.h>
6
7 #include "test_unpriv_bpf_disabled.skel.h"
8
9 #include "cap_helpers.h"
10 #include "bpf_util.h"
11
12 /* Using CAP_LAST_CAP is risky here, since it can get pulled in from
13 * an old /usr/include/linux/capability.h and be < CAP_BPF; as a result
14 * CAP_BPF would not be included in ALL_CAPS. Instead use CAP_BPF as
15 * we know its value is correct since it is explicitly defined in
16 * cap_helpers.h.
17 */
18 #define ALL_CAPS ((2ULL << CAP_BPF) - 1)
19
20 #define PINPATH "/sys/fs/bpf/unpriv_bpf_disabled_"
21 #define NUM_MAPS 7
22
23 static __u32 got_perfbuf_val;
24 static __u32 got_ringbuf_val;
25
process_ringbuf(void * ctx,void * data,size_t len)26 static int process_ringbuf(void *ctx, void *data, size_t len)
27 {
28 if (ASSERT_EQ(len, sizeof(__u32), "ringbuf_size_valid"))
29 got_ringbuf_val = *(__u32 *)data;
30 return 0;
31 }
32
process_perfbuf(void * ctx,int cpu,void * data,__u32 len)33 static void process_perfbuf(void *ctx, int cpu, void *data, __u32 len)
34 {
35 if (ASSERT_EQ(len, sizeof(__u32), "perfbuf_size_valid"))
36 got_perfbuf_val = *(__u32 *)data;
37 }
38
sysctl_set(const char * sysctl_path,char * old_val,const char * new_val)39 static int sysctl_set(const char *sysctl_path, char *old_val, const char *new_val)
40 {
41 int ret = 0;
42 FILE *fp;
43
44 fp = fopen(sysctl_path, "r+");
45 if (!fp)
46 return -errno;
47 if (old_val && fscanf(fp, "%s", old_val) <= 0) {
48 ret = -ENOENT;
49 } else if (!old_val || strcmp(old_val, new_val) != 0) {
50 fseek(fp, 0, SEEK_SET);
51 if (fprintf(fp, "%s", new_val) < 0)
52 ret = -errno;
53 }
54 fclose(fp);
55
56 return ret;
57 }
58
test_unpriv_bpf_disabled_positive(struct test_unpriv_bpf_disabled * skel,__u32 prog_id,int prog_fd,int perf_fd,char ** map_paths,int * map_fds)59 static void test_unpriv_bpf_disabled_positive(struct test_unpriv_bpf_disabled *skel,
60 __u32 prog_id, int prog_fd, int perf_fd,
61 char **map_paths, int *map_fds)
62 {
63 struct perf_buffer *perfbuf = NULL;
64 struct ring_buffer *ringbuf = NULL;
65 int i, nr_cpus, link_fd = -1;
66
67 nr_cpus = bpf_num_possible_cpus();
68
69 skel->bss->perfbuf_val = 1;
70 skel->bss->ringbuf_val = 2;
71
72 /* Positive tests for unprivileged BPF disabled. Verify we can
73 * - retrieve and interact with pinned maps;
74 * - set up and interact with perf buffer;
75 * - set up and interact with ring buffer;
76 * - create a link
77 */
78 perfbuf = perf_buffer__new(bpf_map__fd(skel->maps.perfbuf), 8, process_perfbuf, NULL, NULL,
79 NULL);
80 if (!ASSERT_OK_PTR(perfbuf, "perf_buffer__new"))
81 goto cleanup;
82
83 ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf), process_ringbuf, NULL, NULL);
84 if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
85 goto cleanup;
86
87 /* trigger & validate perf event, ringbuf output */
88 usleep(1);
89
90 ASSERT_GT(perf_buffer__poll(perfbuf, 100), -1, "perf_buffer__poll");
91 ASSERT_EQ(got_perfbuf_val, skel->bss->perfbuf_val, "check_perfbuf_val");
92 ASSERT_EQ(ring_buffer__consume(ringbuf), 1, "ring_buffer__consume");
93 ASSERT_EQ(got_ringbuf_val, skel->bss->ringbuf_val, "check_ringbuf_val");
94
95 for (i = 0; i < NUM_MAPS; i++) {
96 map_fds[i] = bpf_obj_get(map_paths[i]);
97 if (!ASSERT_GT(map_fds[i], -1, "obj_get"))
98 goto cleanup;
99 }
100
101 for (i = 0; i < NUM_MAPS; i++) {
102 bool prog_array = strstr(map_paths[i], "prog_array") != NULL;
103 bool array = strstr(map_paths[i], "array") != NULL;
104 bool buf = strstr(map_paths[i], "buf") != NULL;
105 __u32 key = 0, vals[nr_cpus], lookup_vals[nr_cpus];
106 __u32 expected_val = 1;
107 int j;
108
109 /* skip ringbuf, perfbuf */
110 if (buf)
111 continue;
112
113 for (j = 0; j < nr_cpus; j++)
114 vals[j] = expected_val;
115
116 if (prog_array) {
117 /* need valid prog array value */
118 vals[0] = prog_fd;
119 /* prog array lookup returns prog id, not fd */
120 expected_val = prog_id;
121 }
122 ASSERT_OK(bpf_map_update_elem(map_fds[i], &key, vals, 0), "map_update_elem");
123 ASSERT_OK(bpf_map_lookup_elem(map_fds[i], &key, &lookup_vals), "map_lookup_elem");
124 ASSERT_EQ(lookup_vals[0], expected_val, "map_lookup_elem_values");
125 if (!array)
126 ASSERT_OK(bpf_map_delete_elem(map_fds[i], &key), "map_delete_elem");
127 }
128
129 link_fd = bpf_link_create(bpf_program__fd(skel->progs.handle_perf_event), perf_fd,
130 BPF_PERF_EVENT, NULL);
131 ASSERT_GT(link_fd, 0, "link_create");
132
133 cleanup:
134 if (link_fd)
135 close(link_fd);
136 if (perfbuf)
137 perf_buffer__free(perfbuf);
138 if (ringbuf)
139 ring_buffer__free(ringbuf);
140 }
141
test_unpriv_bpf_disabled_negative(struct test_unpriv_bpf_disabled * skel,__u32 prog_id,int prog_fd,int perf_fd,char ** map_paths,int * map_fds)142 static void test_unpriv_bpf_disabled_negative(struct test_unpriv_bpf_disabled *skel,
143 __u32 prog_id, int prog_fd, int perf_fd,
144 char **map_paths, int *map_fds)
145 {
146 const struct bpf_insn prog_insns[] = {
147 BPF_MOV64_IMM(BPF_REG_0, 0),
148 BPF_EXIT_INSN(),
149 };
150 const size_t prog_insn_cnt = ARRAY_SIZE(prog_insns);
151 LIBBPF_OPTS(bpf_prog_load_opts, load_opts);
152 struct bpf_map_info map_info = {};
153 __u32 map_info_len = sizeof(map_info);
154 struct bpf_link_info link_info = {};
155 __u32 link_info_len = sizeof(link_info);
156 struct btf *btf = NULL;
157 __u32 attach_flags = 0;
158 __u32 prog_ids[3] = {};
159 __u32 prog_cnt = 3;
160 __u32 next;
161 int i;
162
163 /* Negative tests for unprivileged BPF disabled. Verify we cannot
164 * - load BPF programs;
165 * - create BPF maps;
166 * - get a prog/map/link fd by id;
167 * - get next prog/map/link id
168 * - query prog
169 * - BTF load
170 */
171 ASSERT_EQ(bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "simple_prog", "GPL",
172 prog_insns, prog_insn_cnt, &load_opts),
173 -EPERM, "prog_load_fails");
174
175 /* some map types require particular correct parameters which could be
176 * sanity-checked before enforcing -EPERM, so only validate that
177 * the simple ARRAY and HASH maps are failing with -EPERM
178 */
179 for (i = BPF_MAP_TYPE_HASH; i <= BPF_MAP_TYPE_ARRAY; i++)
180 ASSERT_EQ(bpf_map_create(i, NULL, sizeof(int), sizeof(int), 1, NULL),
181 -EPERM, "map_create_fails");
182
183 ASSERT_EQ(bpf_prog_get_fd_by_id(prog_id), -EPERM, "prog_get_fd_by_id_fails");
184 ASSERT_EQ(bpf_prog_get_next_id(prog_id, &next), -EPERM, "prog_get_next_id_fails");
185 ASSERT_EQ(bpf_prog_get_next_id(0, &next), -EPERM, "prog_get_next_id_fails");
186
187 if (ASSERT_OK(bpf_map_get_info_by_fd(map_fds[0], &map_info, &map_info_len),
188 "obj_get_info_by_fd")) {
189 ASSERT_EQ(bpf_map_get_fd_by_id(map_info.id), -EPERM, "map_get_fd_by_id_fails");
190 ASSERT_EQ(bpf_map_get_next_id(map_info.id, &next), -EPERM,
191 "map_get_next_id_fails");
192 }
193 ASSERT_EQ(bpf_map_get_next_id(0, &next), -EPERM, "map_get_next_id_fails");
194
195 if (ASSERT_OK(bpf_link_get_info_by_fd(bpf_link__fd(skel->links.sys_nanosleep_enter),
196 &link_info, &link_info_len),
197 "obj_get_info_by_fd")) {
198 ASSERT_EQ(bpf_link_get_fd_by_id(link_info.id), -EPERM, "link_get_fd_by_id_fails");
199 ASSERT_EQ(bpf_link_get_next_id(link_info.id, &next), -EPERM,
200 "link_get_next_id_fails");
201 }
202 ASSERT_EQ(bpf_link_get_next_id(0, &next), -EPERM, "link_get_next_id_fails");
203
204 ASSERT_EQ(bpf_prog_query(prog_fd, BPF_TRACE_FENTRY, 0, &attach_flags, prog_ids,
205 &prog_cnt), -EPERM, "prog_query_fails");
206
207 btf = btf__new_empty();
208 if (ASSERT_OK_PTR(btf, "empty_btf") &&
209 ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "unpriv_int_type")) {
210 const void *raw_btf_data;
211 __u32 raw_btf_size;
212
213 raw_btf_data = btf__raw_data(btf, &raw_btf_size);
214 if (ASSERT_OK_PTR(raw_btf_data, "raw_btf_data_good"))
215 ASSERT_EQ(bpf_btf_load(raw_btf_data, raw_btf_size, NULL), -EPERM,
216 "bpf_btf_load_fails");
217 }
218 btf__free(btf);
219 }
220
test_unpriv_bpf_disabled(void)221 void test_unpriv_bpf_disabled(void)
222 {
223 char *map_paths[NUM_MAPS] = { PINPATH "array",
224 PINPATH "percpu_array",
225 PINPATH "hash",
226 PINPATH "percpu_hash",
227 PINPATH "perfbuf",
228 PINPATH "ringbuf",
229 PINPATH "prog_array" };
230 int map_fds[NUM_MAPS];
231 struct test_unpriv_bpf_disabled *skel;
232 char unprivileged_bpf_disabled_orig[32] = {};
233 char perf_event_paranoid_orig[32] = {};
234 struct bpf_prog_info prog_info = {};
235 __u32 prog_info_len = sizeof(prog_info);
236 struct perf_event_attr attr = {};
237 int prog_fd, perf_fd = -1, i, ret;
238 __u64 save_caps = 0;
239 __u32 prog_id;
240
241 skel = test_unpriv_bpf_disabled__open_and_load();
242 if (!ASSERT_OK_PTR(skel, "skel_open"))
243 return;
244
245 skel->bss->test_pid = getpid();
246
247 map_fds[0] = bpf_map__fd(skel->maps.array);
248 map_fds[1] = bpf_map__fd(skel->maps.percpu_array);
249 map_fds[2] = bpf_map__fd(skel->maps.hash);
250 map_fds[3] = bpf_map__fd(skel->maps.percpu_hash);
251 map_fds[4] = bpf_map__fd(skel->maps.perfbuf);
252 map_fds[5] = bpf_map__fd(skel->maps.ringbuf);
253 map_fds[6] = bpf_map__fd(skel->maps.prog_array);
254
255 for (i = 0; i < NUM_MAPS; i++)
256 ASSERT_OK(bpf_obj_pin(map_fds[i], map_paths[i]), "pin map_fd");
257
258 /* allow user without caps to use perf events */
259 if (!ASSERT_OK(sysctl_set("/proc/sys/kernel/perf_event_paranoid", perf_event_paranoid_orig,
260 "-1"),
261 "set_perf_event_paranoid"))
262 goto cleanup;
263 /* ensure unprivileged bpf disabled is set */
264 ret = sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled",
265 unprivileged_bpf_disabled_orig, "2");
266 if (ret == -EPERM) {
267 /* if unprivileged_bpf_disabled=1, we get -EPERM back; that's okay. */
268 if (!ASSERT_OK(strcmp(unprivileged_bpf_disabled_orig, "1"),
269 "unprivileged_bpf_disabled_on"))
270 goto cleanup;
271 } else {
272 if (!ASSERT_OK(ret, "set unprivileged_bpf_disabled"))
273 goto cleanup;
274 }
275
276 prog_fd = bpf_program__fd(skel->progs.sys_nanosleep_enter);
277 ASSERT_OK(bpf_prog_get_info_by_fd(prog_fd, &prog_info, &prog_info_len),
278 "obj_get_info_by_fd");
279 prog_id = prog_info.id;
280 ASSERT_GT(prog_id, 0, "valid_prog_id");
281
282 attr.size = sizeof(attr);
283 attr.type = PERF_TYPE_SOFTWARE;
284 attr.config = PERF_COUNT_SW_CPU_CLOCK;
285 attr.freq = 1;
286 attr.sample_freq = 1000;
287 perf_fd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
288 if (!ASSERT_GE(perf_fd, 0, "perf_fd"))
289 goto cleanup;
290
291 if (!ASSERT_OK(test_unpriv_bpf_disabled__attach(skel), "skel_attach"))
292 goto cleanup;
293
294 if (!ASSERT_OK(cap_disable_effective(ALL_CAPS, &save_caps), "disable caps"))
295 goto cleanup;
296
297 if (test__start_subtest("unpriv_bpf_disabled_positive"))
298 test_unpriv_bpf_disabled_positive(skel, prog_id, prog_fd, perf_fd, map_paths,
299 map_fds);
300
301 if (test__start_subtest("unpriv_bpf_disabled_negative"))
302 test_unpriv_bpf_disabled_negative(skel, prog_id, prog_fd, perf_fd, map_paths,
303 map_fds);
304
305 cleanup:
306 close(perf_fd);
307 if (save_caps)
308 cap_enable_effective(save_caps, NULL);
309 if (strlen(perf_event_paranoid_orig) > 0)
310 sysctl_set("/proc/sys/kernel/perf_event_paranoid", NULL, perf_event_paranoid_orig);
311 if (strlen(unprivileged_bpf_disabled_orig) > 0)
312 sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled", NULL,
313 unprivileged_bpf_disabled_orig);
314 for (i = 0; i < NUM_MAPS; i++)
315 unlink(map_paths[i]);
316 test_unpriv_bpf_disabled__destroy(skel);
317 }
318