xref: /linux/tools/bpf/bpftool/net.c (revision 4b660dbd9ee2059850fd30e0df420ca7a38a1856) 
1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 // Copyright (C) 2018 Facebook
3 
4 #ifndef _GNU_SOURCE
5 #define _GNU_SOURCE
6 #endif
7 #include <errno.h>
8 #include <fcntl.h>
9 #include <stdlib.h>
10 #include <string.h>
11 #include <time.h>
12 #include <unistd.h>
13 #include <bpf/bpf.h>
14 #include <bpf/libbpf.h>
15 #include <net/if.h>
16 #include <linux/rtnetlink.h>
17 #include <linux/socket.h>
18 #include <linux/tc_act/tc_bpf.h>
19 #include <sys/socket.h>
20 #include <sys/stat.h>
21 #include <sys/types.h>
22 
23 #include "bpf/nlattr.h"
24 #include "main.h"
25 #include "netlink_dumper.h"
26 
27 #ifndef SOL_NETLINK
28 #define SOL_NETLINK 270
29 #endif
30 
31 struct ip_devname_ifindex {
32 	char	devname[64];
33 	int	ifindex;
34 };
35 
36 struct bpf_netdev_t {
37 	struct ip_devname_ifindex *devices;
38 	int	used_len;
39 	int	array_len;
40 	int	filter_idx;
41 };
42 
43 struct tc_kind_handle {
44 	char	kind[64];
45 	int	handle;
46 };
47 
48 struct bpf_tcinfo_t {
49 	struct tc_kind_handle	*handle_array;
50 	int			used_len;
51 	int			array_len;
52 	bool			is_qdisc;
53 };
54 
55 struct bpf_filter_t {
56 	const char	*kind;
57 	const char	*devname;
58 	int		ifindex;
59 };
60 
61 struct bpf_attach_info {
62 	__u32 flow_dissector_id;
63 };
64 
65 enum net_attach_type {
66 	NET_ATTACH_TYPE_XDP,
67 	NET_ATTACH_TYPE_XDP_GENERIC,
68 	NET_ATTACH_TYPE_XDP_DRIVER,
69 	NET_ATTACH_TYPE_XDP_OFFLOAD,
70 };
71 
72 static const char * const attach_type_strings[] = {
73 	[NET_ATTACH_TYPE_XDP]		= "xdp",
74 	[NET_ATTACH_TYPE_XDP_GENERIC]	= "xdpgeneric",
75 	[NET_ATTACH_TYPE_XDP_DRIVER]	= "xdpdrv",
76 	[NET_ATTACH_TYPE_XDP_OFFLOAD]	= "xdpoffload",
77 };
78 
79 static const char * const attach_loc_strings[] = {
80 	[BPF_TCX_INGRESS]		= "tcx/ingress",
81 	[BPF_TCX_EGRESS]		= "tcx/egress",
82 	[BPF_NETKIT_PRIMARY]		= "netkit/primary",
83 	[BPF_NETKIT_PEER]		= "netkit/peer",
84 };
85 
86 const size_t net_attach_type_size = ARRAY_SIZE(attach_type_strings);
87 
88 static enum net_attach_type parse_attach_type(const char *str)
89 {
90 	enum net_attach_type type;
91 
92 	for (type = 0; type < net_attach_type_size; type++) {
93 		if (attach_type_strings[type] &&
94 		    is_prefix(str, attach_type_strings[type]))
95 			return type;
96 	}
97 
98 	return net_attach_type_size;
99 }
100 
101 typedef int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
102 
103 typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, dump_nlmsg_t, void *cookie);
104 
105 static int netlink_open(__u32 *nl_pid)
106 {
107 	struct sockaddr_nl sa;
108 	socklen_t addrlen;
109 	int one = 1, ret;
110 	int sock;
111 
112 	memset(&sa, 0, sizeof(sa));
113 	sa.nl_family = AF_NETLINK;
114 
115 	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
116 	if (sock < 0)
117 		return -errno;
118 
119 	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
120 		       &one, sizeof(one)) < 0) {
121 		p_err("Netlink error reporting not supported");
122 	}
123 
124 	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
125 		ret = -errno;
126 		goto cleanup;
127 	}
128 
129 	addrlen = sizeof(sa);
130 	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
131 		ret = -errno;
132 		goto cleanup;
133 	}
134 
135 	if (addrlen != sizeof(sa)) {
136 		ret = -LIBBPF_ERRNO__INTERNAL;
137 		goto cleanup;
138 	}
139 
140 	*nl_pid = sa.nl_pid;
141 	return sock;
142 
143 cleanup:
144 	close(sock);
145 	return ret;
146 }
147 
148 static int netlink_recv(int sock, __u32 nl_pid, __u32 seq,
149 			    __dump_nlmsg_t _fn, dump_nlmsg_t fn,
150 			    void *cookie)
151 {
152 	bool multipart = true;
153 	struct nlmsgerr *err;
154 	struct nlmsghdr *nh;
155 	char buf[4096];
156 	int len, ret;
157 
158 	while (multipart) {
159 		multipart = false;
160 		len = recv(sock, buf, sizeof(buf), 0);
161 		if (len < 0) {
162 			ret = -errno;
163 			goto done;
164 		}
165 
166 		if (len == 0)
167 			break;
168 
169 		for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, (unsigned int)len);
170 		     nh = NLMSG_NEXT(nh, len)) {
171 			if (nh->nlmsg_pid != nl_pid) {
172 				ret = -LIBBPF_ERRNO__WRNGPID;
173 				goto done;
174 			}
175 			if (nh->nlmsg_seq != seq) {
176 				ret = -LIBBPF_ERRNO__INVSEQ;
177 				goto done;
178 			}
179 			if (nh->nlmsg_flags & NLM_F_MULTI)
180 				multipart = true;
181 			switch (nh->nlmsg_type) {
182 			case NLMSG_ERROR:
183 				err = (struct nlmsgerr *)NLMSG_DATA(nh);
184 				if (!err->error)
185 					continue;
186 				ret = err->error;
187 				libbpf_nla_dump_errormsg(nh);
188 				goto done;
189 			case NLMSG_DONE:
190 				return 0;
191 			default:
192 				break;
193 			}
194 			if (_fn) {
195 				ret = _fn(nh, fn, cookie);
196 				if (ret)
197 					return ret;
198 			}
199 		}
200 	}
201 	ret = 0;
202 done:
203 	return ret;
204 }
205 
206 static int __dump_class_nlmsg(struct nlmsghdr *nlh,
207 			      dump_nlmsg_t dump_class_nlmsg,
208 			      void *cookie)
209 {
210 	struct nlattr *tb[TCA_MAX + 1], *attr;
211 	struct tcmsg *t = NLMSG_DATA(nlh);
212 	int len;
213 
214 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
215 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
216 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
217 		return -LIBBPF_ERRNO__NLPARSE;
218 
219 	return dump_class_nlmsg(cookie, t, tb);
220 }
221 
222 static int netlink_get_class(int sock, unsigned int nl_pid, int ifindex,
223 			     dump_nlmsg_t dump_class_nlmsg, void *cookie)
224 {
225 	struct {
226 		struct nlmsghdr nlh;
227 		struct tcmsg t;
228 	} req = {
229 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
230 		.nlh.nlmsg_type = RTM_GETTCLASS,
231 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
232 		.t.tcm_family = AF_UNSPEC,
233 		.t.tcm_ifindex = ifindex,
234 	};
235 	int seq = time(NULL);
236 
237 	req.nlh.nlmsg_seq = seq;
238 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
239 		return -errno;
240 
241 	return netlink_recv(sock, nl_pid, seq, __dump_class_nlmsg,
242 			    dump_class_nlmsg, cookie);
243 }
244 
245 static int __dump_qdisc_nlmsg(struct nlmsghdr *nlh,
246 			      dump_nlmsg_t dump_qdisc_nlmsg,
247 			      void *cookie)
248 {
249 	struct nlattr *tb[TCA_MAX + 1], *attr;
250 	struct tcmsg *t = NLMSG_DATA(nlh);
251 	int len;
252 
253 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
254 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
255 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
256 		return -LIBBPF_ERRNO__NLPARSE;
257 
258 	return dump_qdisc_nlmsg(cookie, t, tb);
259 }
260 
261 static int netlink_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
262 			     dump_nlmsg_t dump_qdisc_nlmsg, void *cookie)
263 {
264 	struct {
265 		struct nlmsghdr nlh;
266 		struct tcmsg t;
267 	} req = {
268 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
269 		.nlh.nlmsg_type = RTM_GETQDISC,
270 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
271 		.t.tcm_family = AF_UNSPEC,
272 		.t.tcm_ifindex = ifindex,
273 	};
274 	int seq = time(NULL);
275 
276 	req.nlh.nlmsg_seq = seq;
277 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
278 		return -errno;
279 
280 	return netlink_recv(sock, nl_pid, seq, __dump_qdisc_nlmsg,
281 			    dump_qdisc_nlmsg, cookie);
282 }
283 
284 static int __dump_filter_nlmsg(struct nlmsghdr *nlh,
285 			       dump_nlmsg_t dump_filter_nlmsg,
286 			       void *cookie)
287 {
288 	struct nlattr *tb[TCA_MAX + 1], *attr;
289 	struct tcmsg *t = NLMSG_DATA(nlh);
290 	int len;
291 
292 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
293 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
294 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
295 		return -LIBBPF_ERRNO__NLPARSE;
296 
297 	return dump_filter_nlmsg(cookie, t, tb);
298 }
299 
300 static int netlink_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
301 			      dump_nlmsg_t dump_filter_nlmsg, void *cookie)
302 {
303 	struct {
304 		struct nlmsghdr nlh;
305 		struct tcmsg t;
306 	} req = {
307 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
308 		.nlh.nlmsg_type = RTM_GETTFILTER,
309 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
310 		.t.tcm_family = AF_UNSPEC,
311 		.t.tcm_ifindex = ifindex,
312 		.t.tcm_parent = handle,
313 	};
314 	int seq = time(NULL);
315 
316 	req.nlh.nlmsg_seq = seq;
317 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
318 		return -errno;
319 
320 	return netlink_recv(sock, nl_pid, seq, __dump_filter_nlmsg,
321 			    dump_filter_nlmsg, cookie);
322 }
323 
324 static int __dump_link_nlmsg(struct nlmsghdr *nlh,
325 			     dump_nlmsg_t dump_link_nlmsg, void *cookie)
326 {
327 	struct nlattr *tb[IFLA_MAX + 1], *attr;
328 	struct ifinfomsg *ifi = NLMSG_DATA(nlh);
329 	int len;
330 
331 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
332 	attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
333 	if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
334 		return -LIBBPF_ERRNO__NLPARSE;
335 
336 	return dump_link_nlmsg(cookie, ifi, tb);
337 }
338 
339 static int netlink_get_link(int sock, unsigned int nl_pid,
340 			    dump_nlmsg_t dump_link_nlmsg, void *cookie)
341 {
342 	struct {
343 		struct nlmsghdr nlh;
344 		struct ifinfomsg ifm;
345 	} req = {
346 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
347 		.nlh.nlmsg_type = RTM_GETLINK,
348 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
349 		.ifm.ifi_family = AF_PACKET,
350 	};
351 	int seq = time(NULL);
352 
353 	req.nlh.nlmsg_seq = seq;
354 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
355 		return -errno;
356 
357 	return netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
358 			    dump_link_nlmsg, cookie);
359 }
360 
361 static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
362 {
363 	struct bpf_netdev_t *netinfo = cookie;
364 	struct ifinfomsg *ifinfo = msg;
365 
366 	if (netinfo->filter_idx > 0 && netinfo->filter_idx != ifinfo->ifi_index)
367 		return 0;
368 
369 	if (netinfo->used_len == netinfo->array_len) {
370 		netinfo->devices = realloc(netinfo->devices,
371 			(netinfo->array_len + 16) *
372 			sizeof(struct ip_devname_ifindex));
373 		if (!netinfo->devices)
374 			return -ENOMEM;
375 
376 		netinfo->array_len += 16;
377 	}
378 	netinfo->devices[netinfo->used_len].ifindex = ifinfo->ifi_index;
379 	snprintf(netinfo->devices[netinfo->used_len].devname,
380 		 sizeof(netinfo->devices[netinfo->used_len].devname),
381 		 "%s",
382 		 tb[IFLA_IFNAME]
383 			 ? libbpf_nla_getattr_str(tb[IFLA_IFNAME])
384 			 : "");
385 	netinfo->used_len++;
386 
387 	return do_xdp_dump(ifinfo, tb);
388 }
389 
390 static int dump_class_qdisc_nlmsg(void *cookie, void *msg, struct nlattr **tb)
391 {
392 	struct bpf_tcinfo_t *tcinfo = cookie;
393 	struct tcmsg *info = msg;
394 
395 	if (tcinfo->is_qdisc) {
396 		/* skip clsact qdisc */
397 		if (tb[TCA_KIND] &&
398 		    strcmp(libbpf_nla_data(tb[TCA_KIND]), "clsact") == 0)
399 			return 0;
400 		if (info->tcm_handle == 0)
401 			return 0;
402 	}
403 
404 	if (tcinfo->used_len == tcinfo->array_len) {
405 		tcinfo->handle_array = realloc(tcinfo->handle_array,
406 			(tcinfo->array_len + 16) * sizeof(struct tc_kind_handle));
407 		if (!tcinfo->handle_array)
408 			return -ENOMEM;
409 
410 		tcinfo->array_len += 16;
411 	}
412 	tcinfo->handle_array[tcinfo->used_len].handle = info->tcm_handle;
413 	snprintf(tcinfo->handle_array[tcinfo->used_len].kind,
414 		 sizeof(tcinfo->handle_array[tcinfo->used_len].kind),
415 		 "%s",
416 		 tb[TCA_KIND]
417 			 ? libbpf_nla_getattr_str(tb[TCA_KIND])
418 			 : "unknown");
419 	tcinfo->used_len++;
420 
421 	return 0;
422 }
423 
424 static int dump_filter_nlmsg(void *cookie, void *msg, struct nlattr **tb)
425 {
426 	const struct bpf_filter_t *filter_info = cookie;
427 
428 	return do_filter_dump((struct tcmsg *)msg, tb, filter_info->kind,
429 			      filter_info->devname, filter_info->ifindex);
430 }
431 
432 static int __show_dev_tc_bpf_name(__u32 id, char *name, size_t len)
433 {
434 	struct bpf_prog_info info = {};
435 	__u32 ilen = sizeof(info);
436 	int fd, ret;
437 
438 	fd = bpf_prog_get_fd_by_id(id);
439 	if (fd < 0)
440 		return fd;
441 	ret = bpf_obj_get_info_by_fd(fd, &info, &ilen);
442 	if (ret < 0)
443 		goto out;
444 	ret = -ENOENT;
445 	if (info.name[0]) {
446 		get_prog_full_name(&info, fd, name, len);
447 		ret = 0;
448 	}
449 out:
450 	close(fd);
451 	return ret;
452 }
453 
454 static void __show_dev_tc_bpf(const struct ip_devname_ifindex *dev,
455 			      const enum bpf_attach_type loc)
456 {
457 	__u32 prog_flags[64] = {}, link_flags[64] = {}, i, j;
458 	__u32 prog_ids[64] = {}, link_ids[64] = {};
459 	LIBBPF_OPTS(bpf_prog_query_opts, optq);
460 	char prog_name[MAX_PROG_FULL_NAME];
461 	int ret;
462 
463 	optq.prog_ids = prog_ids;
464 	optq.prog_attach_flags = prog_flags;
465 	optq.link_ids = link_ids;
466 	optq.link_attach_flags = link_flags;
467 	optq.count = ARRAY_SIZE(prog_ids);
468 
469 	ret = bpf_prog_query_opts(dev->ifindex, loc, &optq);
470 	if (ret)
471 		return;
472 	for (i = 0; i < optq.count; i++) {
473 		NET_START_OBJECT;
474 		NET_DUMP_STR("devname", "%s", dev->devname);
475 		NET_DUMP_UINT("ifindex", "(%u)", dev->ifindex);
476 		NET_DUMP_STR("kind", " %s", attach_loc_strings[loc]);
477 		ret = __show_dev_tc_bpf_name(prog_ids[i], prog_name,
478 					     sizeof(prog_name));
479 		if (!ret)
480 			NET_DUMP_STR("name", " %s", prog_name);
481 		NET_DUMP_UINT("prog_id", " prog_id %u ", prog_ids[i]);
482 		if (prog_flags[i] || json_output) {
483 			NET_START_ARRAY("prog_flags", "%s ");
484 			for (j = 0; prog_flags[i] && j < 32; j++) {
485 				if (!(prog_flags[i] & (1 << j)))
486 					continue;
487 				NET_DUMP_UINT_ONLY(1 << j);
488 			}
489 			NET_END_ARRAY("");
490 		}
491 		if (link_ids[i] || json_output) {
492 			NET_DUMP_UINT("link_id", "link_id %u ", link_ids[i]);
493 			if (link_flags[i] || json_output) {
494 				NET_START_ARRAY("link_flags", "%s ");
495 				for (j = 0; link_flags[i] && j < 32; j++) {
496 					if (!(link_flags[i] & (1 << j)))
497 						continue;
498 					NET_DUMP_UINT_ONLY(1 << j);
499 				}
500 				NET_END_ARRAY("");
501 			}
502 		}
503 		NET_END_OBJECT_FINAL;
504 	}
505 }
506 
507 static void show_dev_tc_bpf(struct ip_devname_ifindex *dev)
508 {
509 	__show_dev_tc_bpf(dev, BPF_TCX_INGRESS);
510 	__show_dev_tc_bpf(dev, BPF_TCX_EGRESS);
511 
512 	__show_dev_tc_bpf(dev, BPF_NETKIT_PRIMARY);
513 	__show_dev_tc_bpf(dev, BPF_NETKIT_PEER);
514 }
515 
516 static int show_dev_tc_bpf_classic(int sock, unsigned int nl_pid,
517 				   struct ip_devname_ifindex *dev)
518 {
519 	struct bpf_filter_t filter_info;
520 	struct bpf_tcinfo_t tcinfo;
521 	int i, handle, ret = 0;
522 
523 	tcinfo.handle_array = NULL;
524 	tcinfo.used_len = 0;
525 	tcinfo.array_len = 0;
526 
527 	tcinfo.is_qdisc = false;
528 	ret = netlink_get_class(sock, nl_pid, dev->ifindex,
529 				dump_class_qdisc_nlmsg, &tcinfo);
530 	if (ret)
531 		goto out;
532 
533 	tcinfo.is_qdisc = true;
534 	ret = netlink_get_qdisc(sock, nl_pid, dev->ifindex,
535 				dump_class_qdisc_nlmsg, &tcinfo);
536 	if (ret)
537 		goto out;
538 
539 	filter_info.devname = dev->devname;
540 	filter_info.ifindex = dev->ifindex;
541 	for (i = 0; i < tcinfo.used_len; i++) {
542 		filter_info.kind = tcinfo.handle_array[i].kind;
543 		ret = netlink_get_filter(sock, nl_pid, dev->ifindex,
544 					 tcinfo.handle_array[i].handle,
545 					 dump_filter_nlmsg, &filter_info);
546 		if (ret)
547 			goto out;
548 	}
549 
550 	/* root, ingress and egress handle */
551 	handle = TC_H_ROOT;
552 	filter_info.kind = "root";
553 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
554 				 dump_filter_nlmsg, &filter_info);
555 	if (ret)
556 		goto out;
557 
558 	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS);
559 	filter_info.kind = "clsact/ingress";
560 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
561 				 dump_filter_nlmsg, &filter_info);
562 	if (ret)
563 		goto out;
564 
565 	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS);
566 	filter_info.kind = "clsact/egress";
567 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
568 				 dump_filter_nlmsg, &filter_info);
569 	if (ret)
570 		goto out;
571 
572 out:
573 	free(tcinfo.handle_array);
574 	return 0;
575 }
576 
577 static int query_flow_dissector(struct bpf_attach_info *attach_info)
578 {
579 	__u32 attach_flags;
580 	__u32 prog_ids[1];
581 	__u32 prog_cnt;
582 	int err;
583 	int fd;
584 
585 	fd = open("/proc/self/ns/net", O_RDONLY);
586 	if (fd < 0) {
587 		p_err("can't open /proc/self/ns/net: %s",
588 		      strerror(errno));
589 		return -1;
590 	}
591 	prog_cnt = ARRAY_SIZE(prog_ids);
592 	err = bpf_prog_query(fd, BPF_FLOW_DISSECTOR, 0,
593 			     &attach_flags, prog_ids, &prog_cnt);
594 	close(fd);
595 	if (err) {
596 		if (errno == EINVAL) {
597 			/* Older kernel's don't support querying
598 			 * flow dissector programs.
599 			 */
600 			errno = 0;
601 			return 0;
602 		}
603 		p_err("can't query prog: %s", strerror(errno));
604 		return -1;
605 	}
606 
607 	if (prog_cnt == 1)
608 		attach_info->flow_dissector_id = prog_ids[0];
609 
610 	return 0;
611 }
612 
613 static int net_parse_dev(int *argc, char ***argv)
614 {
615 	int ifindex;
616 
617 	if (is_prefix(**argv, "dev")) {
618 		NEXT_ARGP();
619 
620 		ifindex = if_nametoindex(**argv);
621 		if (!ifindex)
622 			p_err("invalid devname %s", **argv);
623 
624 		NEXT_ARGP();
625 	} else {
626 		p_err("expected 'dev', got: '%s'?", **argv);
627 		return -1;
628 	}
629 
630 	return ifindex;
631 }
632 
633 static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
634 				int ifindex, bool overwrite)
635 {
636 	__u32 flags = 0;
637 
638 	if (!overwrite)
639 		flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
640 	if (attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
641 		flags |= XDP_FLAGS_SKB_MODE;
642 	if (attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
643 		flags |= XDP_FLAGS_DRV_MODE;
644 	if (attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
645 		flags |= XDP_FLAGS_HW_MODE;
646 
647 	return bpf_xdp_attach(ifindex, progfd, flags, NULL);
648 }
649 
650 static int do_attach(int argc, char **argv)
651 {
652 	enum net_attach_type attach_type;
653 	int progfd, ifindex, err = 0;
654 	bool overwrite = false;
655 
656 	/* parse attach args */
657 	if (!REQ_ARGS(5))
658 		return -EINVAL;
659 
660 	attach_type = parse_attach_type(*argv);
661 	if (attach_type == net_attach_type_size) {
662 		p_err("invalid net attach/detach type: %s", *argv);
663 		return -EINVAL;
664 	}
665 	NEXT_ARG();
666 
667 	progfd = prog_parse_fd(&argc, &argv);
668 	if (progfd < 0)
669 		return -EINVAL;
670 
671 	ifindex = net_parse_dev(&argc, &argv);
672 	if (ifindex < 1) {
673 		err = -EINVAL;
674 		goto cleanup;
675 	}
676 
677 	if (argc) {
678 		if (is_prefix(*argv, "overwrite")) {
679 			overwrite = true;
680 		} else {
681 			p_err("expected 'overwrite', got: '%s'?", *argv);
682 			err = -EINVAL;
683 			goto cleanup;
684 		}
685 	}
686 
687 	/* attach xdp prog */
688 	if (is_prefix("xdp", attach_type_strings[attach_type]))
689 		err = do_attach_detach_xdp(progfd, attach_type, ifindex,
690 					   overwrite);
691 	if (err) {
692 		p_err("interface %s attach failed: %s",
693 		      attach_type_strings[attach_type], strerror(-err));
694 		goto cleanup;
695 	}
696 
697 	if (json_output)
698 		jsonw_null(json_wtr);
699 cleanup:
700 	close(progfd);
701 	return err;
702 }
703 
704 static int do_detach(int argc, char **argv)
705 {
706 	enum net_attach_type attach_type;
707 	int progfd, ifindex, err = 0;
708 
709 	/* parse detach args */
710 	if (!REQ_ARGS(3))
711 		return -EINVAL;
712 
713 	attach_type = parse_attach_type(*argv);
714 	if (attach_type == net_attach_type_size) {
715 		p_err("invalid net attach/detach type: %s", *argv);
716 		return -EINVAL;
717 	}
718 	NEXT_ARG();
719 
720 	ifindex = net_parse_dev(&argc, &argv);
721 	if (ifindex < 1)
722 		return -EINVAL;
723 
724 	/* detach xdp prog */
725 	progfd = -1;
726 	if (is_prefix("xdp", attach_type_strings[attach_type]))
727 		err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL);
728 
729 	if (err < 0) {
730 		p_err("interface %s detach failed: %s",
731 		      attach_type_strings[attach_type], strerror(-err));
732 		return err;
733 	}
734 
735 	if (json_output)
736 		jsonw_null(json_wtr);
737 
738 	return 0;
739 }
740 
741 static int netfilter_link_compar(const void *a, const void *b)
742 {
743 	const struct bpf_link_info *nfa = a;
744 	const struct bpf_link_info *nfb = b;
745 	int delta;
746 
747 	delta = nfa->netfilter.pf - nfb->netfilter.pf;
748 	if (delta)
749 		return delta;
750 
751 	delta = nfa->netfilter.hooknum - nfb->netfilter.hooknum;
752 	if (delta)
753 		return delta;
754 
755 	if (nfa->netfilter.priority < nfb->netfilter.priority)
756 		return -1;
757 	if (nfa->netfilter.priority > nfb->netfilter.priority)
758 		return 1;
759 
760 	return nfa->netfilter.flags - nfb->netfilter.flags;
761 }
762 
763 static void show_link_netfilter(void)
764 {
765 	unsigned int nf_link_len = 0, nf_link_count = 0;
766 	struct bpf_link_info *nf_link_info = NULL;
767 	__u32 id = 0;
768 
769 	while (true) {
770 		struct bpf_link_info info;
771 		int fd, err;
772 		__u32 len;
773 
774 		err = bpf_link_get_next_id(id, &id);
775 		if (err) {
776 			if (errno == ENOENT)
777 				break;
778 			p_err("can't get next link: %s (id %d)", strerror(errno), id);
779 			break;
780 		}
781 
782 		fd = bpf_link_get_fd_by_id(id);
783 		if (fd < 0) {
784 			p_err("can't get link by id (%u): %s", id, strerror(errno));
785 			continue;
786 		}
787 
788 		memset(&info, 0, sizeof(info));
789 		len = sizeof(info);
790 
791 		err = bpf_link_get_info_by_fd(fd, &info, &len);
792 
793 		close(fd);
794 
795 		if (err) {
796 			p_err("can't get link info for fd %d: %s", fd, strerror(errno));
797 			continue;
798 		}
799 
800 		if (info.type != BPF_LINK_TYPE_NETFILTER)
801 			continue;
802 
803 		if (nf_link_count >= nf_link_len) {
804 			static const unsigned int max_link_count = INT_MAX / sizeof(info);
805 			struct bpf_link_info *expand;
806 
807 			if (nf_link_count > max_link_count) {
808 				p_err("cannot handle more than %u links\n", max_link_count);
809 				break;
810 			}
811 
812 			nf_link_len += 16;
813 
814 			expand = realloc(nf_link_info, nf_link_len * sizeof(info));
815 			if (!expand) {
816 				p_err("realloc: %s",  strerror(errno));
817 				break;
818 			}
819 
820 			nf_link_info = expand;
821 		}
822 
823 		nf_link_info[nf_link_count] = info;
824 		nf_link_count++;
825 	}
826 
827 	qsort(nf_link_info, nf_link_count, sizeof(*nf_link_info), netfilter_link_compar);
828 
829 	for (id = 0; id < nf_link_count; id++) {
830 		NET_START_OBJECT;
831 		if (json_output)
832 			netfilter_dump_json(&nf_link_info[id], json_wtr);
833 		else
834 			netfilter_dump_plain(&nf_link_info[id]);
835 
836 		NET_DUMP_UINT("id", " prog_id %u", nf_link_info[id].prog_id);
837 		NET_END_OBJECT;
838 	}
839 
840 	free(nf_link_info);
841 }
842 
843 static int do_show(int argc, char **argv)
844 {
845 	struct bpf_attach_info attach_info = {};
846 	int i, sock, ret, filter_idx = -1;
847 	struct bpf_netdev_t dev_array;
848 	unsigned int nl_pid = 0;
849 	char err_buf[256];
850 
851 	if (argc == 2) {
852 		filter_idx = net_parse_dev(&argc, &argv);
853 		if (filter_idx < 1)
854 			return -1;
855 	} else if (argc != 0) {
856 		usage();
857 	}
858 
859 	ret = query_flow_dissector(&attach_info);
860 	if (ret)
861 		return -1;
862 
863 	sock = netlink_open(&nl_pid);
864 	if (sock < 0) {
865 		fprintf(stderr, "failed to open netlink sock\n");
866 		return -1;
867 	}
868 
869 	dev_array.devices = NULL;
870 	dev_array.used_len = 0;
871 	dev_array.array_len = 0;
872 	dev_array.filter_idx = filter_idx;
873 
874 	if (json_output)
875 		jsonw_start_array(json_wtr);
876 	NET_START_OBJECT;
877 	NET_START_ARRAY("xdp", "%s:\n");
878 	ret = netlink_get_link(sock, nl_pid, dump_link_nlmsg, &dev_array);
879 	NET_END_ARRAY("\n");
880 
881 	if (!ret) {
882 		NET_START_ARRAY("tc", "%s:\n");
883 		for (i = 0; i < dev_array.used_len; i++) {
884 			show_dev_tc_bpf(&dev_array.devices[i]);
885 			ret = show_dev_tc_bpf_classic(sock, nl_pid,
886 						      &dev_array.devices[i]);
887 			if (ret)
888 				break;
889 		}
890 		NET_END_ARRAY("\n");
891 	}
892 
893 	NET_START_ARRAY("flow_dissector", "%s:\n");
894 	if (attach_info.flow_dissector_id > 0)
895 		NET_DUMP_UINT("id", "id %u", attach_info.flow_dissector_id);
896 	NET_END_ARRAY("\n");
897 
898 	NET_START_ARRAY("netfilter", "%s:\n");
899 	show_link_netfilter();
900 	NET_END_ARRAY("\n");
901 
902 	NET_END_OBJECT;
903 	if (json_output)
904 		jsonw_end_array(json_wtr);
905 
906 	if (ret) {
907 		if (json_output)
908 			jsonw_null(json_wtr);
909 		libbpf_strerror(ret, err_buf, sizeof(err_buf));
910 		fprintf(stderr, "Error: %s\n", err_buf);
911 	}
912 	free(dev_array.devices);
913 	close(sock);
914 	return ret;
915 }
916 
917 static int do_help(int argc, char **argv)
918 {
919 	if (json_output) {
920 		jsonw_null(json_wtr);
921 		return 0;
922 	}
923 
924 	fprintf(stderr,
925 		"Usage: %1$s %2$s { show | list } [dev <devname>]\n"
926 		"       %1$s %2$s attach ATTACH_TYPE PROG dev <devname> [ overwrite ]\n"
927 		"       %1$s %2$s detach ATTACH_TYPE dev <devname>\n"
928 		"       %1$s %2$s help\n"
929 		"\n"
930 		"       " HELP_SPEC_PROGRAM "\n"
931 		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
932 		"       " HELP_SPEC_OPTIONS " }\n"
933 		"\n"
934 		"Note: Only xdp, tcx, tc, netkit, flow_dissector and netfilter attachments\n"
935 		"      are currently supported.\n"
936 		"      For progs attached to cgroups, use \"bpftool cgroup\"\n"
937 		"      to dump program attachments. For program types\n"
938 		"      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
939 		"      consult iproute2.\n"
940 		"",
941 		bin_name, argv[-2]);
942 
943 	return 0;
944 }
945 
946 static const struct cmd cmds[] = {
947 	{ "show",	do_show },
948 	{ "list",	do_show },
949 	{ "attach",	do_attach },
950 	{ "detach",	do_detach },
951 	{ "help",	do_help },
952 	{ 0 }
953 };
954 
955 int do_net(int argc, char **argv)
956 {
957 	return cmd_select(cmds, argc, argv, do_help);
958 }
959