tools/bpf/bpftool/link.c

   1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2 /* Copyright (C) 2020 Facebook */
   3
   4 #include <errno.h>
   5 #include <net/if.h>
   6 #include <stdio.h>
   7 #include <unistd.h>
   8
   9 #include <bpf/bpf.h>
  10
  11 #include "json_writer.h"
  12 #include "main.h"
  13
  14 static const char * const link_type_name[] = {
  15         [BPF_LINK_TYPE_UNSPEC]                  = "unspec",
  16         [BPF_LINK_TYPE_RAW_TRACEPOINT]          = "raw_tracepoint",
  17         [BPF_LINK_TYPE_TRACING]                 = "tracing",
  18         [BPF_LINK_TYPE_CGROUP]                  = "cgroup",
  19         [BPF_LINK_TYPE_ITER]                    = "iter",
  20         [BPF_LINK_TYPE_NETNS]                   = "netns",
  21 };
  22
  23 static int link_parse_fd(int *argc, char ***argv)
  24 {
  25         int fd;
  26
  27         if (is_prefix(**argv, "id")) {
  28                 unsigned int id;
  29                 char *endptr;
  30
  31                 NEXT_ARGP();
  32
  33                 id = strtoul(**argv, &endptr, 0);
  34                 if (*endptr) {
  35                         p_err("can't parse %s as ID", **argv);
  36                         return -1;
  37                 }
  38                 NEXT_ARGP();
  39
  40                 fd = bpf_link_get_fd_by_id(id);
  41                 if (fd < 0)
  42                         p_err("failed to get link with ID %d: %s", id, strerror(errno));
  43                 return fd;
  44         } else if (is_prefix(**argv, "pinned")) {
  45                 char *path;
  46
  47                 NEXT_ARGP();
  48
  49                 path = **argv;
  50                 NEXT_ARGP();
  51
  52                 return open_obj_pinned_any(path, BPF_OBJ_LINK);
  53         }
  54
  55         p_err("expected 'id' or 'pinned', got: '%s'?", **argv);
  56         return -1;
  57 }
  58
  59 static void
  60 show_link_header_json(struct bpf_link_info *info, json_writer_t *wtr)
  61 {
  62         jsonw_uint_field(wtr, "id", info->id);
  63         if (info->type < ARRAY_SIZE(link_type_name))
  64                 jsonw_string_field(wtr, "type", link_type_name[info->type]);
  65         else
  66                 jsonw_uint_field(wtr, "type", info->type);
  67
  68         jsonw_uint_field(json_wtr, "prog_id", info->prog_id);
  69 }
  70
  71 static void show_link_attach_type_json(__u32 attach_type, json_writer_t *wtr)
  72 {
  73         if (attach_type < ARRAY_SIZE(attach_type_name))
  74                 jsonw_string_field(wtr, "attach_type",
  75                                    attach_type_name[attach_type]);
  76         else
  77                 jsonw_uint_field(wtr, "attach_type", attach_type);
  78 }
  79
  80 static bool is_iter_map_target(const char *target_name)
  81 {
  82         return strcmp(target_name, "bpf_map_elem") == 0 ||
  83                strcmp(target_name, "bpf_sk_storage_map") == 0;
  84 }
  85
  86 static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)
  87 {
  88         const char *target_name = u64_to_ptr(info->iter.target_name);
  89
  90         jsonw_string_field(wtr, "target_name", target_name);
  91
  92         if (is_iter_map_target(target_name))
  93                 jsonw_uint_field(wtr, "map_id", info->iter.map.map_id);
  94 }
  95
  96 static int get_prog_info(int prog_id, struct bpf_prog_info *info)
  97 {
  98         __u32 len = sizeof(*info);
  99         int err, prog_fd;
 100
 101         prog_fd = bpf_prog_get_fd_by_id(prog_id);
 102         if (prog_fd < 0)
 103                 return prog_fd;
 104
 105         memset(info, 0, sizeof(*info));
 106         err = bpf_obj_get_info_by_fd(prog_fd, info, &len);
 107         if (err)
 108                 p_err("can't get prog info: %s", strerror(errno));
 109         close(prog_fd);
 110         return err;
 111 }
 112
 113 static int show_link_close_json(int fd, struct bpf_link_info *info)
 114 {
 115         struct bpf_prog_info prog_info;
 116         int err;
 117
 118         jsonw_start_object(json_wtr);
 119
 120         show_link_header_json(info, json_wtr);
 121
 122         switch (info->type) {
 123         case BPF_LINK_TYPE_RAW_TRACEPOINT:
 124                 jsonw_string_field(json_wtr, "tp_name",
 125                                    u64_to_ptr(info->raw_tracepoint.tp_name));
 126                 break;
 127         case BPF_LINK_TYPE_TRACING:
 128                 err = get_prog_info(info->prog_id, &prog_info);
 129                 if (err)
 130                         return err;
 131
 132                 if (prog_info.type < prog_type_name_size)
 133                         jsonw_string_field(json_wtr, "prog_type",
 134                                            prog_type_name[prog_info.type]);
 135                 else
 136                         jsonw_uint_field(json_wtr, "prog_type",
 137                                          prog_info.type);
 138
 139                 show_link_attach_type_json(info->tracing.attach_type,
 140                                            json_wtr);
 141                 break;
 142         case BPF_LINK_TYPE_CGROUP:
 143                 jsonw_lluint_field(json_wtr, "cgroup_id",
 144                                    info->cgroup.cgroup_id);
 145                 show_link_attach_type_json(info->cgroup.attach_type, json_wtr);
 146                 break;
 147         case BPF_LINK_TYPE_ITER:
 148                 show_iter_json(info, json_wtr);
 149                 break;
 150         case BPF_LINK_TYPE_NETNS:
 151                 jsonw_uint_field(json_wtr, "netns_ino",
 152                                  info->netns.netns_ino);
 153                 show_link_attach_type_json(info->netns.attach_type, json_wtr);
 154                 break;
 155         default:
 156                 break;
 157         }
 158
 159         if (!hash_empty(link_table.table)) {
 160                 struct pinned_obj *obj;
 161
 162                 jsonw_name(json_wtr, "pinned");
 163                 jsonw_start_array(json_wtr);
 164                 hash_for_each_possible(link_table.table, obj, hash, info->id) {
 165                         if (obj->id == info->id)
 166                                 jsonw_string(json_wtr, obj->path);
 167                 }
 168                 jsonw_end_array(json_wtr);
 169         }
 170
 171         emit_obj_refs_json(&refs_table, info->id, json_wtr);
 172
 173         jsonw_end_object(json_wtr);
 174
 175         return 0;
 176 }
 177
 178 static void show_link_header_plain(struct bpf_link_info *info)
 179 {
 180         printf("%u: ", info->id);
 181         if (info->type < ARRAY_SIZE(link_type_name))
 182                 printf("%s  ", link_type_name[info->type]);
 183         else
 184                 printf("type %u  ", info->type);
 185
 186         printf("prog %u  ", info->prog_id);
 187 }
 188
 189 static void show_link_attach_type_plain(__u32 attach_type)
 190 {
 191         if (attach_type < ARRAY_SIZE(attach_type_name))
 192                 printf("attach_type %s  ", attach_type_name[attach_type]);
 193         else
 194                 printf("attach_type %u  ", attach_type);
 195 }
 196
 197 static void show_iter_plain(struct bpf_link_info *info)
 198 {
 199         const char *target_name = u64_to_ptr(info->iter.target_name);
 200
 201         printf("target_name %s  ", target_name);
 202
 203         if (is_iter_map_target(target_name))
 204                 printf("map_id %u  ", info->iter.map.map_id);
 205 }
 206
 207 static int show_link_close_plain(int fd, struct bpf_link_info *info)
 208 {
 209         struct bpf_prog_info prog_info;
 210         int err;
 211
 212         show_link_header_plain(info);
 213
 214         switch (info->type) {
 215         case BPF_LINK_TYPE_RAW_TRACEPOINT:
 216                 printf("\n\ttp '%s'  ",
 217                        (const char *)u64_to_ptr(info->raw_tracepoint.tp_name));
 218                 break;
 219         case BPF_LINK_TYPE_TRACING:
 220                 err = get_prog_info(info->prog_id, &prog_info);
 221                 if (err)
 222                         return err;
 223
 224                 if (prog_info.type < prog_type_name_size)
 225                         printf("\n\tprog_type %s  ",
 226                                prog_type_name[prog_info.type]);
 227                 else
 228                         printf("\n\tprog_type %u  ", prog_info.type);
 229
 230                 show_link_attach_type_plain(info->tracing.attach_type);
 231                 break;
 232         case BPF_LINK_TYPE_CGROUP:
 233                 printf("\n\tcgroup_id %zu  ", (size_t)info->cgroup.cgroup_id);
 234                 show_link_attach_type_plain(info->cgroup.attach_type);
 235                 break;
 236         case BPF_LINK_TYPE_ITER:
 237                 show_iter_plain(info);
 238                 break;
 239         case BPF_LINK_TYPE_NETNS:
 240                 printf("\n\tnetns_ino %u  ", info->netns.netns_ino);
 241                 show_link_attach_type_plain(info->netns.attach_type);
 242                 break;
 243         default:
 244                 break;
 245         }
 246
 247         if (!hash_empty(link_table.table)) {
 248                 struct pinned_obj *obj;
 249
 250                 hash_for_each_possible(link_table.table, obj, hash, info->id) {
 251                         if (obj->id == info->id)
 252                                 printf("\n\tpinned %s", obj->path);
 253                 }
 254         }
 255         emit_obj_refs_plain(&refs_table, info->id, "\n\tpids ");
 256
 257         printf("\n");
 258
 259         return 0;
 260 }
 261
 262 static int do_show_link(int fd)
 263 {
 264         struct bpf_link_info info;
 265         __u32 len = sizeof(info);
 266         char buf[256];
 267         int err;
 268
 269         memset(&info, 0, sizeof(info));
 270 again:
 271         err = bpf_obj_get_info_by_fd(fd, &info, &len);
 272         if (err) {
 273                 p_err("can't get link info: %s",
 274                       strerror(errno));
 275                 close(fd);
 276                 return err;
 277         }
 278         if (info.type == BPF_LINK_TYPE_RAW_TRACEPOINT &&
 279             !info.raw_tracepoint.tp_name) {
 280                 info.raw_tracepoint.tp_name = (unsigned long)&buf;
 281                 info.raw_tracepoint.tp_name_len = sizeof(buf);
 282                 goto again;
 283         }
 284         if (info.type == BPF_LINK_TYPE_ITER &&
 285             !info.iter.target_name) {
 286                 info.iter.target_name = (unsigned long)&buf;
 287                 info.iter.target_name_len = sizeof(buf);
 288                 goto again;
 289         }
 290
 291         if (json_output)
 292                 show_link_close_json(fd, &info);
 293         else
 294                 show_link_close_plain(fd, &info);
 295
 296         close(fd);
 297         return 0;
 298 }
 299
 300 static int do_show(int argc, char **argv)
 301 {
 302         __u32 id = 0;
 303         int err, fd;
 304
 305         if (show_pinned)
 306                 build_pinned_obj_table(&link_table, BPF_OBJ_LINK);
 307         build_obj_refs_table(&refs_table, BPF_OBJ_LINK);
 308
 309         if (argc == 2) {
 310                 fd = link_parse_fd(&argc, &argv);
 311                 if (fd < 0)
 312                         return fd;
 313                 return do_show_link(fd);
 314         }
 315
 316         if (argc)
 317                 return BAD_ARG();
 318
 319         if (json_output)
 320                 jsonw_start_array(json_wtr);
 321         while (true) {
 322                 err = bpf_link_get_next_id(id, &id);
 323                 if (err) {
 324                         if (errno == ENOENT)
 325                                 break;
 326                         p_err("can't get next link: %s%s", strerror(errno),
 327                               errno == EINVAL ? " -- kernel too old?" : "");
 328                         break;
 329                 }
 330
 331                 fd = bpf_link_get_fd_by_id(id);
 332                 if (fd < 0) {
 333                         if (errno == ENOENT)
 334                                 continue;
 335                         p_err("can't get link by id (%u): %s",
 336                               id, strerror(errno));
 337                         break;
 338                 }
 339
 340                 err = do_show_link(fd);
 341                 if (err)
 342                         break;
 343         }
 344         if (json_output)
 345                 jsonw_end_array(json_wtr);
 346
 347         delete_obj_refs_table(&refs_table);
 348
 349         return errno == ENOENT ? 0 : -1;
 350 }
 351
 352 static int do_pin(int argc, char **argv)
 353 {
 354         int err;
 355
 356         err = do_pin_any(argc, argv, link_parse_fd);
 357         if (!err && json_output)
 358                 jsonw_null(json_wtr);
 359         return err;
 360 }
 361
 362 static int do_detach(int argc, char **argv)
 363 {
 364         int err, fd;
 365
 366         if (argc != 2) {
 367                 p_err("link specifier is invalid or missing\n");
 368                 return 1;
 369         }
 370
 371         fd = link_parse_fd(&argc, &argv);
 372         if (fd < 0)
 373                 return 1;
 374
 375         err = bpf_link_detach(fd);
 376         if (err)
 377                 err = -errno;
 378         close(fd);
 379         if (err) {
 380                 p_err("failed link detach: %s", strerror(-err));
 381                 return 1;
 382         }
 383
 384         if (json_output)
 385                 jsonw_null(json_wtr);
 386
 387         return 0;
 388 }
 389
 390 static int do_help(int argc, char **argv)
 391 {
 392         if (json_output) {
 393                 jsonw_null(json_wtr);
 394                 return 0;
 395         }
 396
 397         fprintf(stderr,
 398                 "Usage: %1$s %2$s { show | list }   [LINK]\n"
 399                 "       %1$s %2$s pin        LINK  FILE\n"
 400                 "       %1$s %2$s detach     LINK\n"
 401                 "       %1$s %2$s help\n"
 402                 "\n"
 403                 "       " HELP_SPEC_LINK "\n"
 404                 "       " HELP_SPEC_OPTIONS "\n"
 405                 "",
 406                 bin_name, argv[-2]);
 407
 408         return 0;
 409 }
 410
 411 static const struct cmd cmds[] = {
 412         { "show",       do_show },
 413         { "list",       do_show },
 414         { "help",       do_help },
 415         { "pin",        do_pin },
 416         { "detach",     do_detach },
 417         { 0 }
 418 };
 419
 420 int do_link(int argc, char **argv)
 421 {
 422         return cmd_select(cmds, argc, argv, do_help);
 423 }