xref: /openbmc/linux/tools/bpf/bpftool/net.c (revision df0e68c1) 
1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 // Copyright (C) 2018 Facebook
3 
4 #define _GNU_SOURCE
5 #include <errno.h>
6 #include <fcntl.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <time.h>
10 #include <unistd.h>
11 #include <bpf/bpf.h>
12 #include <bpf/libbpf.h>
13 #include <net/if.h>
14 #include <linux/rtnetlink.h>
15 #include <linux/socket.h>
16 #include <linux/tc_act/tc_bpf.h>
17 #include <sys/socket.h>
18 #include <sys/stat.h>
19 #include <sys/types.h>
20 
21 #include "bpf/nlattr.h"
22 #include "main.h"
23 #include "netlink_dumper.h"
24 
25 #ifndef SOL_NETLINK
26 #define SOL_NETLINK 270
27 #endif
28 
29 struct ip_devname_ifindex {
30 	char	devname[64];
31 	int	ifindex;
32 };
33 
34 struct bpf_netdev_t {
35 	struct ip_devname_ifindex *devices;
36 	int	used_len;
37 	int	array_len;
38 	int	filter_idx;
39 };
40 
41 struct tc_kind_handle {
42 	char	kind[64];
43 	int	handle;
44 };
45 
46 struct bpf_tcinfo_t {
47 	struct tc_kind_handle	*handle_array;
48 	int			used_len;
49 	int			array_len;
50 	bool			is_qdisc;
51 };
52 
53 struct bpf_filter_t {
54 	const char	*kind;
55 	const char	*devname;
56 	int		ifindex;
57 };
58 
59 struct bpf_attach_info {
60 	__u32 flow_dissector_id;
61 };
62 
63 enum net_attach_type {
64 	NET_ATTACH_TYPE_XDP,
65 	NET_ATTACH_TYPE_XDP_GENERIC,
66 	NET_ATTACH_TYPE_XDP_DRIVER,
67 	NET_ATTACH_TYPE_XDP_OFFLOAD,
68 };
69 
70 static const char * const attach_type_strings[] = {
71 	[NET_ATTACH_TYPE_XDP]		= "xdp",
72 	[NET_ATTACH_TYPE_XDP_GENERIC]	= "xdpgeneric",
73 	[NET_ATTACH_TYPE_XDP_DRIVER]	= "xdpdrv",
74 	[NET_ATTACH_TYPE_XDP_OFFLOAD]	= "xdpoffload",
75 };
76 
77 const size_t net_attach_type_size = ARRAY_SIZE(attach_type_strings);
78 
79 static enum net_attach_type parse_attach_type(const char *str)
80 {
81 	enum net_attach_type type;
82 
83 	for (type = 0; type < net_attach_type_size; type++) {
84 		if (attach_type_strings[type] &&
85 		    is_prefix(str, attach_type_strings[type]))
86 			return type;
87 	}
88 
89 	return net_attach_type_size;
90 }
91 
92 typedef int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
93 
94 typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, dump_nlmsg_t, void *cookie);
95 
96 static int netlink_open(__u32 *nl_pid)
97 {
98 	struct sockaddr_nl sa;
99 	socklen_t addrlen;
100 	int one = 1, ret;
101 	int sock;
102 
103 	memset(&sa, 0, sizeof(sa));
104 	sa.nl_family = AF_NETLINK;
105 
106 	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
107 	if (sock < 0)
108 		return -errno;
109 
110 	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
111 		       &one, sizeof(one)) < 0) {
112 		p_err("Netlink error reporting not supported");
113 	}
114 
115 	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
116 		ret = -errno;
117 		goto cleanup;
118 	}
119 
120 	addrlen = sizeof(sa);
121 	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
122 		ret = -errno;
123 		goto cleanup;
124 	}
125 
126 	if (addrlen != sizeof(sa)) {
127 		ret = -LIBBPF_ERRNO__INTERNAL;
128 		goto cleanup;
129 	}
130 
131 	*nl_pid = sa.nl_pid;
132 	return sock;
133 
134 cleanup:
135 	close(sock);
136 	return ret;
137 }
138 
139 static int netlink_recv(int sock, __u32 nl_pid, __u32 seq,
140 			    __dump_nlmsg_t _fn, dump_nlmsg_t fn,
141 			    void *cookie)
142 {
143 	bool multipart = true;
144 	struct nlmsgerr *err;
145 	struct nlmsghdr *nh;
146 	char buf[4096];
147 	int len, ret;
148 
149 	while (multipart) {
150 		multipart = false;
151 		len = recv(sock, buf, sizeof(buf), 0);
152 		if (len < 0) {
153 			ret = -errno;
154 			goto done;
155 		}
156 
157 		if (len == 0)
158 			break;
159 
160 		for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, (unsigned int)len);
161 		     nh = NLMSG_NEXT(nh, len)) {
162 			if (nh->nlmsg_pid != nl_pid) {
163 				ret = -LIBBPF_ERRNO__WRNGPID;
164 				goto done;
165 			}
166 			if (nh->nlmsg_seq != seq) {
167 				ret = -LIBBPF_ERRNO__INVSEQ;
168 				goto done;
169 			}
170 			if (nh->nlmsg_flags & NLM_F_MULTI)
171 				multipart = true;
172 			switch (nh->nlmsg_type) {
173 			case NLMSG_ERROR:
174 				err = (struct nlmsgerr *)NLMSG_DATA(nh);
175 				if (!err->error)
176 					continue;
177 				ret = err->error;
178 				libbpf_nla_dump_errormsg(nh);
179 				goto done;
180 			case NLMSG_DONE:
181 				return 0;
182 			default:
183 				break;
184 			}
185 			if (_fn) {
186 				ret = _fn(nh, fn, cookie);
187 				if (ret)
188 					return ret;
189 			}
190 		}
191 	}
192 	ret = 0;
193 done:
194 	return ret;
195 }
196 
197 static int __dump_class_nlmsg(struct nlmsghdr *nlh,
198 			      dump_nlmsg_t dump_class_nlmsg,
199 			      void *cookie)
200 {
201 	struct nlattr *tb[TCA_MAX + 1], *attr;
202 	struct tcmsg *t = NLMSG_DATA(nlh);
203 	int len;
204 
205 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
206 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
207 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
208 		return -LIBBPF_ERRNO__NLPARSE;
209 
210 	return dump_class_nlmsg(cookie, t, tb);
211 }
212 
213 static int netlink_get_class(int sock, unsigned int nl_pid, int ifindex,
214 			     dump_nlmsg_t dump_class_nlmsg, void *cookie)
215 {
216 	struct {
217 		struct nlmsghdr nlh;
218 		struct tcmsg t;
219 	} req = {
220 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
221 		.nlh.nlmsg_type = RTM_GETTCLASS,
222 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
223 		.t.tcm_family = AF_UNSPEC,
224 		.t.tcm_ifindex = ifindex,
225 	};
226 	int seq = time(NULL);
227 
228 	req.nlh.nlmsg_seq = seq;
229 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
230 		return -errno;
231 
232 	return netlink_recv(sock, nl_pid, seq, __dump_class_nlmsg,
233 			    dump_class_nlmsg, cookie);
234 }
235 
236 static int __dump_qdisc_nlmsg(struct nlmsghdr *nlh,
237 			      dump_nlmsg_t dump_qdisc_nlmsg,
238 			      void *cookie)
239 {
240 	struct nlattr *tb[TCA_MAX + 1], *attr;
241 	struct tcmsg *t = NLMSG_DATA(nlh);
242 	int len;
243 
244 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
245 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
246 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
247 		return -LIBBPF_ERRNO__NLPARSE;
248 
249 	return dump_qdisc_nlmsg(cookie, t, tb);
250 }
251 
252 static int netlink_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
253 			     dump_nlmsg_t dump_qdisc_nlmsg, void *cookie)
254 {
255 	struct {
256 		struct nlmsghdr nlh;
257 		struct tcmsg t;
258 	} req = {
259 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
260 		.nlh.nlmsg_type = RTM_GETQDISC,
261 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
262 		.t.tcm_family = AF_UNSPEC,
263 		.t.tcm_ifindex = ifindex,
264 	};
265 	int seq = time(NULL);
266 
267 	req.nlh.nlmsg_seq = seq;
268 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
269 		return -errno;
270 
271 	return netlink_recv(sock, nl_pid, seq, __dump_qdisc_nlmsg,
272 			    dump_qdisc_nlmsg, cookie);
273 }
274 
275 static int __dump_filter_nlmsg(struct nlmsghdr *nlh,
276 			       dump_nlmsg_t dump_filter_nlmsg,
277 			       void *cookie)
278 {
279 	struct nlattr *tb[TCA_MAX + 1], *attr;
280 	struct tcmsg *t = NLMSG_DATA(nlh);
281 	int len;
282 
283 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
284 	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
285 	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
286 		return -LIBBPF_ERRNO__NLPARSE;
287 
288 	return dump_filter_nlmsg(cookie, t, tb);
289 }
290 
291 static int netlink_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
292 			      dump_nlmsg_t dump_filter_nlmsg, void *cookie)
293 {
294 	struct {
295 		struct nlmsghdr nlh;
296 		struct tcmsg t;
297 	} req = {
298 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
299 		.nlh.nlmsg_type = RTM_GETTFILTER,
300 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
301 		.t.tcm_family = AF_UNSPEC,
302 		.t.tcm_ifindex = ifindex,
303 		.t.tcm_parent = handle,
304 	};
305 	int seq = time(NULL);
306 
307 	req.nlh.nlmsg_seq = seq;
308 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
309 		return -errno;
310 
311 	return netlink_recv(sock, nl_pid, seq, __dump_filter_nlmsg,
312 			    dump_filter_nlmsg, cookie);
313 }
314 
315 static int __dump_link_nlmsg(struct nlmsghdr *nlh,
316 			     dump_nlmsg_t dump_link_nlmsg, void *cookie)
317 {
318 	struct nlattr *tb[IFLA_MAX + 1], *attr;
319 	struct ifinfomsg *ifi = NLMSG_DATA(nlh);
320 	int len;
321 
322 	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
323 	attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
324 	if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
325 		return -LIBBPF_ERRNO__NLPARSE;
326 
327 	return dump_link_nlmsg(cookie, ifi, tb);
328 }
329 
330 static int netlink_get_link(int sock, unsigned int nl_pid,
331 			    dump_nlmsg_t dump_link_nlmsg, void *cookie)
332 {
333 	struct {
334 		struct nlmsghdr nlh;
335 		struct ifinfomsg ifm;
336 	} req = {
337 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
338 		.nlh.nlmsg_type = RTM_GETLINK,
339 		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
340 		.ifm.ifi_family = AF_PACKET,
341 	};
342 	int seq = time(NULL);
343 
344 	req.nlh.nlmsg_seq = seq;
345 	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
346 		return -errno;
347 
348 	return netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
349 			    dump_link_nlmsg, cookie);
350 }
351 
352 static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
353 {
354 	struct bpf_netdev_t *netinfo = cookie;
355 	struct ifinfomsg *ifinfo = msg;
356 
357 	if (netinfo->filter_idx > 0 && netinfo->filter_idx != ifinfo->ifi_index)
358 		return 0;
359 
360 	if (netinfo->used_len == netinfo->array_len) {
361 		netinfo->devices = realloc(netinfo->devices,
362 			(netinfo->array_len + 16) *
363 			sizeof(struct ip_devname_ifindex));
364 		if (!netinfo->devices)
365 			return -ENOMEM;
366 
367 		netinfo->array_len += 16;
368 	}
369 	netinfo->devices[netinfo->used_len].ifindex = ifinfo->ifi_index;
370 	snprintf(netinfo->devices[netinfo->used_len].devname,
371 		 sizeof(netinfo->devices[netinfo->used_len].devname),
372 		 "%s",
373 		 tb[IFLA_IFNAME]
374 			 ? libbpf_nla_getattr_str(tb[IFLA_IFNAME])
375 			 : "");
376 	netinfo->used_len++;
377 
378 	return do_xdp_dump(ifinfo, tb);
379 }
380 
381 static int dump_class_qdisc_nlmsg(void *cookie, void *msg, struct nlattr **tb)
382 {
383 	struct bpf_tcinfo_t *tcinfo = cookie;
384 	struct tcmsg *info = msg;
385 
386 	if (tcinfo->is_qdisc) {
387 		/* skip clsact qdisc */
388 		if (tb[TCA_KIND] &&
389 		    strcmp(libbpf_nla_data(tb[TCA_KIND]), "clsact") == 0)
390 			return 0;
391 		if (info->tcm_handle == 0)
392 			return 0;
393 	}
394 
395 	if (tcinfo->used_len == tcinfo->array_len) {
396 		tcinfo->handle_array = realloc(tcinfo->handle_array,
397 			(tcinfo->array_len + 16) * sizeof(struct tc_kind_handle));
398 		if (!tcinfo->handle_array)
399 			return -ENOMEM;
400 
401 		tcinfo->array_len += 16;
402 	}
403 	tcinfo->handle_array[tcinfo->used_len].handle = info->tcm_handle;
404 	snprintf(tcinfo->handle_array[tcinfo->used_len].kind,
405 		 sizeof(tcinfo->handle_array[tcinfo->used_len].kind),
406 		 "%s",
407 		 tb[TCA_KIND]
408 			 ? libbpf_nla_getattr_str(tb[TCA_KIND])
409 			 : "unknown");
410 	tcinfo->used_len++;
411 
412 	return 0;
413 }
414 
415 static int dump_filter_nlmsg(void *cookie, void *msg, struct nlattr **tb)
416 {
417 	const struct bpf_filter_t *filter_info = cookie;
418 
419 	return do_filter_dump((struct tcmsg *)msg, tb, filter_info->kind,
420 			      filter_info->devname, filter_info->ifindex);
421 }
422 
423 static int show_dev_tc_bpf(int sock, unsigned int nl_pid,
424 			   struct ip_devname_ifindex *dev)
425 {
426 	struct bpf_filter_t filter_info;
427 	struct bpf_tcinfo_t tcinfo;
428 	int i, handle, ret = 0;
429 
430 	tcinfo.handle_array = NULL;
431 	tcinfo.used_len = 0;
432 	tcinfo.array_len = 0;
433 
434 	tcinfo.is_qdisc = false;
435 	ret = netlink_get_class(sock, nl_pid, dev->ifindex,
436 				dump_class_qdisc_nlmsg, &tcinfo);
437 	if (ret)
438 		goto out;
439 
440 	tcinfo.is_qdisc = true;
441 	ret = netlink_get_qdisc(sock, nl_pid, dev->ifindex,
442 				dump_class_qdisc_nlmsg, &tcinfo);
443 	if (ret)
444 		goto out;
445 
446 	filter_info.devname = dev->devname;
447 	filter_info.ifindex = dev->ifindex;
448 	for (i = 0; i < tcinfo.used_len; i++) {
449 		filter_info.kind = tcinfo.handle_array[i].kind;
450 		ret = netlink_get_filter(sock, nl_pid, dev->ifindex,
451 					 tcinfo.handle_array[i].handle,
452 					 dump_filter_nlmsg, &filter_info);
453 		if (ret)
454 			goto out;
455 	}
456 
457 	/* root, ingress and egress handle */
458 	handle = TC_H_ROOT;
459 	filter_info.kind = "root";
460 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
461 				 dump_filter_nlmsg, &filter_info);
462 	if (ret)
463 		goto out;
464 
465 	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS);
466 	filter_info.kind = "clsact/ingress";
467 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
468 				 dump_filter_nlmsg, &filter_info);
469 	if (ret)
470 		goto out;
471 
472 	handle = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS);
473 	filter_info.kind = "clsact/egress";
474 	ret = netlink_get_filter(sock, nl_pid, dev->ifindex, handle,
475 				 dump_filter_nlmsg, &filter_info);
476 	if (ret)
477 		goto out;
478 
479 out:
480 	free(tcinfo.handle_array);
481 	return 0;
482 }
483 
484 static int query_flow_dissector(struct bpf_attach_info *attach_info)
485 {
486 	__u32 attach_flags;
487 	__u32 prog_ids[1];
488 	__u32 prog_cnt;
489 	int err;
490 	int fd;
491 
492 	fd = open("/proc/self/ns/net", O_RDONLY);
493 	if (fd < 0) {
494 		p_err("can't open /proc/self/ns/net: %s",
495 		      strerror(errno));
496 		return -1;
497 	}
498 	prog_cnt = ARRAY_SIZE(prog_ids);
499 	err = bpf_prog_query(fd, BPF_FLOW_DISSECTOR, 0,
500 			     &attach_flags, prog_ids, &prog_cnt);
501 	close(fd);
502 	if (err) {
503 		if (errno == EINVAL) {
504 			/* Older kernel's don't support querying
505 			 * flow dissector programs.
506 			 */
507 			errno = 0;
508 			return 0;
509 		}
510 		p_err("can't query prog: %s", strerror(errno));
511 		return -1;
512 	}
513 
514 	if (prog_cnt == 1)
515 		attach_info->flow_dissector_id = prog_ids[0];
516 
517 	return 0;
518 }
519 
520 static int net_parse_dev(int *argc, char ***argv)
521 {
522 	int ifindex;
523 
524 	if (is_prefix(**argv, "dev")) {
525 		NEXT_ARGP();
526 
527 		ifindex = if_nametoindex(**argv);
528 		if (!ifindex)
529 			p_err("invalid devname %s", **argv);
530 
531 		NEXT_ARGP();
532 	} else {
533 		p_err("expected 'dev', got: '%s'?", **argv);
534 		return -1;
535 	}
536 
537 	return ifindex;
538 }
539 
540 static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
541 				int ifindex, bool overwrite)
542 {
543 	__u32 flags = 0;
544 
545 	if (!overwrite)
546 		flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
547 	if (attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
548 		flags |= XDP_FLAGS_SKB_MODE;
549 	if (attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
550 		flags |= XDP_FLAGS_DRV_MODE;
551 	if (attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
552 		flags |= XDP_FLAGS_HW_MODE;
553 
554 	return bpf_set_link_xdp_fd(ifindex, progfd, flags);
555 }
556 
557 static int do_attach(int argc, char **argv)
558 {
559 	enum net_attach_type attach_type;
560 	int progfd, ifindex, err = 0;
561 	bool overwrite = false;
562 
563 	/* parse attach args */
564 	if (!REQ_ARGS(5))
565 		return -EINVAL;
566 
567 	attach_type = parse_attach_type(*argv);
568 	if (attach_type == net_attach_type_size) {
569 		p_err("invalid net attach/detach type: %s", *argv);
570 		return -EINVAL;
571 	}
572 	NEXT_ARG();
573 
574 	progfd = prog_parse_fd(&argc, &argv);
575 	if (progfd < 0)
576 		return -EINVAL;
577 
578 	ifindex = net_parse_dev(&argc, &argv);
579 	if (ifindex < 1) {
580 		err = -EINVAL;
581 		goto cleanup;
582 	}
583 
584 	if (argc) {
585 		if (is_prefix(*argv, "overwrite")) {
586 			overwrite = true;
587 		} else {
588 			p_err("expected 'overwrite', got: '%s'?", *argv);
589 			err = -EINVAL;
590 			goto cleanup;
591 		}
592 	}
593 
594 	/* attach xdp prog */
595 	if (is_prefix("xdp", attach_type_strings[attach_type]))
596 		err = do_attach_detach_xdp(progfd, attach_type, ifindex,
597 					   overwrite);
598 	if (err) {
599 		p_err("interface %s attach failed: %s",
600 		      attach_type_strings[attach_type], strerror(-err));
601 		goto cleanup;
602 	}
603 
604 	if (json_output)
605 		jsonw_null(json_wtr);
606 cleanup:
607 	close(progfd);
608 	return err;
609 }
610 
611 static int do_detach(int argc, char **argv)
612 {
613 	enum net_attach_type attach_type;
614 	int progfd, ifindex, err = 0;
615 
616 	/* parse detach args */
617 	if (!REQ_ARGS(3))
618 		return -EINVAL;
619 
620 	attach_type = parse_attach_type(*argv);
621 	if (attach_type == net_attach_type_size) {
622 		p_err("invalid net attach/detach type: %s", *argv);
623 		return -EINVAL;
624 	}
625 	NEXT_ARG();
626 
627 	ifindex = net_parse_dev(&argc, &argv);
628 	if (ifindex < 1)
629 		return -EINVAL;
630 
631 	/* detach xdp prog */
632 	progfd = -1;
633 	if (is_prefix("xdp", attach_type_strings[attach_type]))
634 		err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL);
635 
636 	if (err < 0) {
637 		p_err("interface %s detach failed: %s",
638 		      attach_type_strings[attach_type], strerror(-err));
639 		return err;
640 	}
641 
642 	if (json_output)
643 		jsonw_null(json_wtr);
644 
645 	return 0;
646 }
647 
648 static int do_show(int argc, char **argv)
649 {
650 	struct bpf_attach_info attach_info = {};
651 	int i, sock, ret, filter_idx = -1;
652 	struct bpf_netdev_t dev_array;
653 	unsigned int nl_pid = 0;
654 	char err_buf[256];
655 
656 	if (argc == 2) {
657 		filter_idx = net_parse_dev(&argc, &argv);
658 		if (filter_idx < 1)
659 			return -1;
660 	} else if (argc != 0) {
661 		usage();
662 	}
663 
664 	ret = query_flow_dissector(&attach_info);
665 	if (ret)
666 		return -1;
667 
668 	sock = netlink_open(&nl_pid);
669 	if (sock < 0) {
670 		fprintf(stderr, "failed to open netlink sock\n");
671 		return -1;
672 	}
673 
674 	dev_array.devices = NULL;
675 	dev_array.used_len = 0;
676 	dev_array.array_len = 0;
677 	dev_array.filter_idx = filter_idx;
678 
679 	if (json_output)
680 		jsonw_start_array(json_wtr);
681 	NET_START_OBJECT;
682 	NET_START_ARRAY("xdp", "%s:\n");
683 	ret = netlink_get_link(sock, nl_pid, dump_link_nlmsg, &dev_array);
684 	NET_END_ARRAY("\n");
685 
686 	if (!ret) {
687 		NET_START_ARRAY("tc", "%s:\n");
688 		for (i = 0; i < dev_array.used_len; i++) {
689 			ret = show_dev_tc_bpf(sock, nl_pid,
690 					      &dev_array.devices[i]);
691 			if (ret)
692 				break;
693 		}
694 		NET_END_ARRAY("\n");
695 	}
696 
697 	NET_START_ARRAY("flow_dissector", "%s:\n");
698 	if (attach_info.flow_dissector_id > 0)
699 		NET_DUMP_UINT("id", "id %u", attach_info.flow_dissector_id);
700 	NET_END_ARRAY("\n");
701 
702 	NET_END_OBJECT;
703 	if (json_output)
704 		jsonw_end_array(json_wtr);
705 
706 	if (ret) {
707 		if (json_output)
708 			jsonw_null(json_wtr);
709 		libbpf_strerror(ret, err_buf, sizeof(err_buf));
710 		fprintf(stderr, "Error: %s\n", err_buf);
711 	}
712 	free(dev_array.devices);
713 	close(sock);
714 	return ret;
715 }
716 
717 static int do_help(int argc, char **argv)
718 {
719 	if (json_output) {
720 		jsonw_null(json_wtr);
721 		return 0;
722 	}
723 
724 	fprintf(stderr,
725 		"Usage: %1$s %2$s { show | list } [dev <devname>]\n"
726 		"       %1$s %2$s attach ATTACH_TYPE PROG dev <devname> [ overwrite ]\n"
727 		"       %1$s %2$s detach ATTACH_TYPE dev <devname>\n"
728 		"       %1$s %2$s help\n"
729 		"\n"
730 		"       " HELP_SPEC_PROGRAM "\n"
731 		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
732 		"       " HELP_SPEC_OPTIONS " }\n"
733 		"\n"
734 		"Note: Only xdp and tc attachments are supported now.\n"
735 		"      For progs attached to cgroups, use \"bpftool cgroup\"\n"
736 		"      to dump program attachments. For program types\n"
737 		"      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
738 		"      consult iproute2.\n"
739 		"",
740 		bin_name, argv[-2]);
741 
742 	return 0;
743 }
744 
745 static const struct cmd cmds[] = {
746 	{ "show",	do_show },
747 	{ "list",	do_show },
748 	{ "attach",	do_attach },
749 	{ "detach",	do_detach },
750 	{ "help",	do_help },
751 	{ 0 }
752 };
753 
754 int do_net(int argc, char **argv)
755 {
756 	return cmd_select(cmds, argc, argv, do_help);
757 }
758