net.c

   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                 "\n"
 733                 "Note: Only xdp and tc attachments are supported now.\n"
 734                 "      For progs attached to cgroups, use \"bpftool cgroup\"\n"
 735                 "      to dump program attachments. For program types\n"
 736                 "      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
 737                 "      consult iproute2.\n"
 738                 "",
 739                 bin_name, argv[-2]);
 740
 741         return 0;
 742 }
 743
 744 static const struct cmd cmds[] = {
 745         { "show",       do_show },
 746         { "list",       do_show },
 747         { "attach",     do_attach },
 748         { "detach",     do_detach },
 749         { "help",       do_help },
 750         { 0 }
 751 };
 752
 753 int do_net(int argc, char **argv)
 754 {
 755         return cmd_select(cmds, argc, argv, do_help);
 756 }