samples/bpf/bpf_load.c

   1 #include <stdio.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <fcntl.h>
   5 #include <libelf.h>
   6 #include <gelf.h>
   7 #include <errno.h>
   8 #include <unistd.h>
   9 #include <string.h>
  10 #include <stdbool.h>
  11 #include <stdlib.h>
  12 #include <linux/bpf.h>
  13 #include <linux/filter.h>
  14 #include <linux/perf_event.h>
  15 #include <linux/netlink.h>
  16 #include <linux/rtnetlink.h>
  17 #include <linux/types.h>
  18 #include <sys/types.h>
  19 #include <sys/socket.h>
  20 #include <sys/syscall.h>
  21 #include <sys/ioctl.h>
  22 #include <sys/mman.h>
  23 #include <poll.h>
  24 #include <ctype.h>
  25 #include <assert.h>
  26 #include "libbpf.h"
  27 #include "bpf_load.h"
  28 #include "perf-sys.h"
  29
  30 #define DEBUGFS "/sys/kernel/debug/tracing/"
  31
  32 static char license[128];
  33 static int kern_version;
  34 static bool processed_sec[128];
  35 char bpf_log_buf[BPF_LOG_BUF_SIZE];
  36 int map_fd[MAX_MAPS];
  37 int prog_fd[MAX_PROGS];
  38 int event_fd[MAX_PROGS];
  39 int prog_cnt;
  40 int prog_array_fd = -1;
  41
  42 static int populate_prog_array(const char *event, int prog_fd)
  43 {
  44         int ind = atoi(event), err;
  45
  46         err = bpf_map_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
  47         if (err < 0) {
  48                 printf("failed to store prog_fd in prog_array\n");
  49                 return -1;
  50         }
  51         return 0;
  52 }
  53
  54 static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
  55 {
  56         bool is_socket = strncmp(event, "socket", 6) == 0;
  57         bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
  58         bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
  59         bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
  60         bool is_xdp = strncmp(event, "xdp", 3) == 0;
  61         bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
  62         bool is_cgroup_skb = strncmp(event, "cgroup/skb", 10) == 0;
  63         bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;
  64         size_t insns_cnt = size / sizeof(struct bpf_insn);
  65         enum bpf_prog_type prog_type;
  66         char buf[256];
  67         int fd, efd, err, id;
  68         struct perf_event_attr attr = {};
  69
  70         attr.type = PERF_TYPE_TRACEPOINT;
  71         attr.sample_type = PERF_SAMPLE_RAW;
  72         attr.sample_period = 1;
  73         attr.wakeup_events = 1;
  74
  75         if (is_socket) {
  76                 prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
  77         } else if (is_kprobe || is_kretprobe) {
  78                 prog_type = BPF_PROG_TYPE_KPROBE;
  79         } else if (is_tracepoint) {
  80                 prog_type = BPF_PROG_TYPE_TRACEPOINT;
  81         } else if (is_xdp) {
  82                 prog_type = BPF_PROG_TYPE_XDP;
  83         } else if (is_perf_event) {
  84                 prog_type = BPF_PROG_TYPE_PERF_EVENT;
  85         } else if (is_cgroup_skb) {
  86                 prog_type = BPF_PROG_TYPE_CGROUP_SKB;
  87         } else if (is_cgroup_sk) {
  88                 prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
  89         } else {
  90                 printf("Unknown event '%s'\n", event);
  91                 return -1;
  92         }
  93
  94         fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
  95                               bpf_log_buf, BPF_LOG_BUF_SIZE);
  96         if (fd < 0) {
  97                 printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
  98                 return -1;
  99         }
 100
 101         prog_fd[prog_cnt++] = fd;
 102
 103         if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
 104                 return 0;
 105
 106         if (is_socket) {
 107                 event += 6;
 108                 if (*event != '/')
 109                         return 0;
 110                 event++;
 111                 if (!isdigit(*event)) {
 112                         printf("invalid prog number\n");
 113                         return -1;
 114                 }
 115                 return populate_prog_array(event, fd);
 116         }
 117
 118         if (is_kprobe || is_kretprobe) {
 119                 if (is_kprobe)
 120                         event += 7;
 121                 else
 122                         event += 10;
 123
 124                 if (*event == 0) {
 125                         printf("event name cannot be empty\n");
 126                         return -1;
 127                 }
 128
 129                 if (isdigit(*event))
 130                         return populate_prog_array(event, fd);
 131
 132                 snprintf(buf, sizeof(buf),
 133                          "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
 134                          is_kprobe ? 'p' : 'r', event, event);
 135                 err = system(buf);
 136                 if (err < 0) {
 137                         printf("failed to create kprobe '%s' error '%s'\n",
 138                                event, strerror(errno));
 139                         return -1;
 140                 }
 141
 142                 strcpy(buf, DEBUGFS);
 143                 strcat(buf, "events/kprobes/");
 144                 strcat(buf, event);
 145                 strcat(buf, "/id");
 146         } else if (is_tracepoint) {
 147                 event += 11;
 148
 149                 if (*event == 0) {
 150                         printf("event name cannot be empty\n");
 151                         return -1;
 152                 }
 153                 strcpy(buf, DEBUGFS);
 154                 strcat(buf, "events/");
 155                 strcat(buf, event);
 156                 strcat(buf, "/id");
 157         }
 158
 159         efd = open(buf, O_RDONLY, 0);
 160         if (efd < 0) {
 161                 printf("failed to open event %s\n", event);
 162                 return -1;
 163         }
 164
 165         err = read(efd, buf, sizeof(buf));
 166         if (err < 0 || err >= sizeof(buf)) {
 167                 printf("read from '%s' failed '%s'\n", event, strerror(errno));
 168                 return -1;
 169         }
 170
 171         close(efd);
 172
 173         buf[err] = 0;
 174         id = atoi(buf);
 175         attr.config = id;
 176
 177         efd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
 178         if (efd < 0) {
 179                 printf("event %d fd %d err %s\n", id, efd, strerror(errno));
 180                 return -1;
 181         }
 182         event_fd[prog_cnt - 1] = efd;
 183         ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
 184         ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
 185
 186         return 0;
 187 }
 188
 189 static int load_maps(struct bpf_map_def *maps, int nr_maps,
 190                      const char **map_names, fixup_map_cb fixup_map)
 191 {
 192         int i;
 193         /*
 194          * Warning: Using "maps" pointing to ELF data_maps->d_buf as
 195          * an array of struct bpf_map_def is a wrong assumption about
 196          * the ELF maps section format.
 197          */
 198         for (i = 0; i < nr_maps; i++) {
 199                 if (fixup_map)
 200                         fixup_map(&maps[i], map_names[i], i);
 201
 202                 if (maps[i].type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
 203                     maps[i].type == BPF_MAP_TYPE_HASH_OF_MAPS) {
 204                         int inner_map_fd = map_fd[maps[i].inner_map_idx];
 205
 206                         map_fd[i] = bpf_create_map_in_map(maps[i].type,
 207                                                           maps[i].key_size,
 208                                                           inner_map_fd,
 209                                                           maps[i].max_entries,
 210                                                           maps[i].map_flags);
 211                 } else {
 212                         map_fd[i] = bpf_create_map(maps[i].type,
 213                                                    maps[i].key_size,
 214                                                    maps[i].value_size,
 215                                                    maps[i].max_entries,
 216                                                    maps[i].map_flags);
 217                 }
 218                 if (map_fd[i] < 0) {
 219                         printf("failed to create a map: %d %s\n",
 220                                errno, strerror(errno));
 221                         return 1;
 222                 }
 223
 224                 if (maps[i].type == BPF_MAP_TYPE_PROG_ARRAY)
 225                         prog_array_fd = map_fd[i];
 226         }
 227         return 0;
 228 }
 229
 230 static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
 231                    GElf_Shdr *shdr, Elf_Data **data)
 232 {
 233         Elf_Scn *scn;
 234
 235         scn = elf_getscn(elf, i);
 236         if (!scn)
 237                 return 1;
 238
 239         if (gelf_getshdr(scn, shdr) != shdr)
 240                 return 2;
 241
 242         *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
 243         if (!*shname || !shdr->sh_size)
 244                 return 3;
 245
 246         *data = elf_getdata(scn, 0);
 247         if (!*data || elf_getdata(scn, *data) != NULL)
 248                 return 4;
 249
 250         return 0;
 251 }
 252
 253 static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
 254                                 GElf_Shdr *shdr, struct bpf_insn *insn)
 255 {
 256         int i, nrels;
 257
 258         nrels = shdr->sh_size / shdr->sh_entsize;
 259
 260         for (i = 0; i < nrels; i++) {
 261                 GElf_Sym sym;
 262                 GElf_Rel rel;
 263                 unsigned int insn_idx;
 264
 265                 gelf_getrel(data, i, &rel);
 266
 267                 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
 268
 269                 gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
 270
 271                 if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
 272                         printf("invalid relo for insn[%d].code 0x%x\n",
 273                                insn_idx, insn[insn_idx].code);
 274                         return 1;
 275                 }
 276                 insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
 277                 /*
 278                  * Warning: Using sizeof(struct bpf_map_def) here is a
 279                  * wrong assumption about ELF maps section format
 280                  */
 281                 insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)];
 282         }
 283
 284         return 0;
 285 }
 286
 287 static int cmp_symbols(const void *l, const void *r)
 288 {
 289         const GElf_Sym *lsym = (const GElf_Sym *)l;
 290         const GElf_Sym *rsym = (const GElf_Sym *)r;
 291
 292         if (lsym->st_value < rsym->st_value)
 293                 return -1;
 294         else if (lsym->st_value > rsym->st_value)
 295                 return 1;
 296         else
 297                 return 0;
 298 }
 299
 300 static int get_sorted_map_names(Elf *elf, Elf_Data *symbols, int maps_shndx,
 301                                 int strtabidx, char **map_names)
 302 {
 303         GElf_Sym map_symbols[MAX_MAPS];
 304         int i, nr_maps = 0;
 305
 306         for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
 307                 assert(nr_maps < MAX_MAPS);
 308                 if (!gelf_getsym(symbols, i, &map_symbols[nr_maps]))
 309                         continue;
 310                 if (map_symbols[nr_maps].st_shndx != maps_shndx)
 311                         continue;
 312                 nr_maps++;
 313         }
 314
 315         qsort(map_symbols, nr_maps, sizeof(GElf_Sym), cmp_symbols);
 316
 317         for (i = 0; i < nr_maps; i++) {
 318                 char *map_name;
 319
 320                 map_name = elf_strptr(elf, strtabidx, map_symbols[i].st_name);
 321                 if (!map_name) {
 322                         printf("cannot get map symbol\n");
 323                         return -1;
 324                 }
 325
 326                 map_names[i] = strdup(map_name);
 327                 if (!map_names[i]) {
 328                         printf("strdup(%s): %s(%d)\n", map_name,
 329                                strerror(errno), errno);
 330                         return -1;
 331                 }
 332         }
 333
 334         return nr_maps;
 335 }
 336
 337 static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
 338 {
 339         int fd, i, ret, maps_shndx = -1, strtabidx = -1;
 340         Elf *elf;
 341         GElf_Ehdr ehdr;
 342         GElf_Shdr shdr, shdr_prog;
 343         Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;
 344         char *shname, *shname_prog, *map_names[MAX_MAPS] = { NULL };
 345
 346         /* reset global variables */
 347         kern_version = 0;
 348         memset(license, 0, sizeof(license));
 349         memset(processed_sec, 0, sizeof(processed_sec));
 350
 351         if (elf_version(EV_CURRENT) == EV_NONE)
 352                 return 1;
 353
 354         fd = open(path, O_RDONLY, 0);
 355         if (fd < 0)
 356                 return 1;
 357
 358         elf = elf_begin(fd, ELF_C_READ, NULL);
 359
 360         if (!elf)
 361                 return 1;
 362
 363         if (gelf_getehdr(elf, &ehdr) != &ehdr)
 364                 return 1;
 365
 366         /* clear all kprobes */
 367         i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
 368
 369         /* scan over all elf sections to get license and map info */
 370         for (i = 1; i < ehdr.e_shnum; i++) {
 371
 372                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 373                         continue;
 374
 375                 if (0) /* helpful for llvm debugging */
 376                         printf("section %d:%s data %p size %zd link %d flags %d\n",
 377                                i, shname, data->d_buf, data->d_size,
 378                                shdr.sh_link, (int) shdr.sh_flags);
 379
 380                 if (strcmp(shname, "license") == 0) {
 381                         processed_sec[i] = true;
 382                         memcpy(license, data->d_buf, data->d_size);
 383                 } else if (strcmp(shname, "version") == 0) {
 384                         processed_sec[i] = true;
 385                         if (data->d_size != sizeof(int)) {
 386                                 printf("invalid size of version section %zd\n",
 387                                        data->d_size);
 388                                 return 1;
 389                         }
 390                         memcpy(&kern_version, data->d_buf, sizeof(int));
 391                 } else if (strcmp(shname, "maps") == 0) {
 392                         maps_shndx = i;
 393                         data_maps = data;
 394                 } else if (shdr.sh_type == SHT_SYMTAB) {
 395                         strtabidx = shdr.sh_link;
 396                         symbols = data;
 397                 }
 398         }
 399
 400         ret = 1;
 401
 402         if (!symbols) {
 403                 printf("missing SHT_SYMTAB section\n");
 404                 goto done;
 405         }
 406
 407         if (data_maps) {
 408                 int nr_maps;
 409                 int prog_elf_map_sz;
 410
 411                 nr_maps = get_sorted_map_names(elf, symbols, maps_shndx,
 412                                                strtabidx, map_names);
 413                 if (nr_maps < 0)
 414                         goto done;
 415
 416                 /* Deduce map struct size stored in ELF maps section */
 417                 prog_elf_map_sz = data_maps->d_size / nr_maps;
 418                 if (prog_elf_map_sz != sizeof(struct bpf_map_def)) {
 419                         printf("Error: ELF maps sec wrong size (%d/%lu),"
 420                                " old kern.o file?\n",
 421                                prog_elf_map_sz, sizeof(struct bpf_map_def));
 422                         ret = 1;
 423                         goto done;
 424                 }
 425
 426                 if (load_maps(data_maps->d_buf, nr_maps,
 427                               (const char **)map_names, fixup_map))
 428                         goto done;
 429
 430                 processed_sec[maps_shndx] = true;
 431         }
 432
 433         /* load programs that need map fixup (relocations) */
 434         for (i = 1; i < ehdr.e_shnum; i++) {
 435                 if (processed_sec[i])
 436                         continue;
 437
 438                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 439                         continue;
 440                 if (shdr.sh_type == SHT_REL) {
 441                         struct bpf_insn *insns;
 442
 443                         if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
 444                                     &shdr_prog, &data_prog))
 445                                 continue;
 446
 447                         if (shdr_prog.sh_type != SHT_PROGBITS ||
 448                             !(shdr_prog.sh_flags & SHF_EXECINSTR))
 449                                 continue;
 450
 451                         insns = (struct bpf_insn *) data_prog->d_buf;
 452
 453                         processed_sec[shdr.sh_info] = true;
 454                         processed_sec[i] = true;
 455
 456                         if (parse_relo_and_apply(data, symbols, &shdr, insns))
 457                                 continue;
 458
 459                         if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
 460                             memcmp(shname_prog, "kretprobe/", 10) == 0 ||
 461                             memcmp(shname_prog, "tracepoint/", 11) == 0 ||
 462                             memcmp(shname_prog, "xdp", 3) == 0 ||
 463                             memcmp(shname_prog, "perf_event", 10) == 0 ||
 464                             memcmp(shname_prog, "socket", 6) == 0 ||
 465                             memcmp(shname_prog, "cgroup/", 7) == 0)
 466                                 load_and_attach(shname_prog, insns, data_prog->d_size);
 467                 }
 468         }
 469
 470         /* load programs that don't use maps */
 471         for (i = 1; i < ehdr.e_shnum; i++) {
 472
 473                 if (processed_sec[i])
 474                         continue;
 475
 476                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 477                         continue;
 478
 479                 if (memcmp(shname, "kprobe/", 7) == 0 ||
 480                     memcmp(shname, "kretprobe/", 10) == 0 ||
 481                     memcmp(shname, "tracepoint/", 11) == 0 ||
 482                     memcmp(shname, "xdp", 3) == 0 ||
 483                     memcmp(shname, "perf_event", 10) == 0 ||
 484                     memcmp(shname, "socket", 6) == 0 ||
 485                     memcmp(shname, "cgroup/", 7) == 0)
 486                         load_and_attach(shname, data->d_buf, data->d_size);
 487         }
 488
 489         ret = 0;
 490 done:
 491         for (i = 0; i < MAX_MAPS; i++)
 492                 free(map_names[i]);
 493         close(fd);
 494         return ret;
 495 }
 496
 497 int load_bpf_file(char *path)
 498 {
 499         return do_load_bpf_file(path, NULL);
 500 }
 501
 502 int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
 503 {
 504         return do_load_bpf_file(path, fixup_map);
 505 }
 506
 507 void read_trace_pipe(void)
 508 {
 509         int trace_fd;
 510
 511         trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
 512         if (trace_fd < 0)
 513                 return;
 514
 515         while (1) {
 516                 static char buf[4096];
 517                 ssize_t sz;
 518
 519                 sz = read(trace_fd, buf, sizeof(buf));
 520                 if (sz > 0) {
 521                         buf[sz] = 0;
 522                         puts(buf);
 523                 }
 524         }
 525 }
 526
 527 #define MAX_SYMS 300000
 528 static struct ksym syms[MAX_SYMS];
 529 static int sym_cnt;
 530
 531 static int ksym_cmp(const void *p1, const void *p2)
 532 {
 533         return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
 534 }
 535
 536 int load_kallsyms(void)
 537 {
 538         FILE *f = fopen("/proc/kallsyms", "r");
 539         char func[256], buf[256];
 540         char symbol;
 541         void *addr;
 542         int i = 0;
 543
 544         if (!f)
 545                 return -ENOENT;
 546
 547         while (!feof(f)) {
 548                 if (!fgets(buf, sizeof(buf), f))
 549                         break;
 550                 if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
 551                         break;
 552                 if (!addr)
 553                         continue;
 554                 syms[i].addr = (long) addr;
 555                 syms[i].name = strdup(func);
 556                 i++;
 557         }
 558         sym_cnt = i;
 559         qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
 560         return 0;
 561 }
 562
 563 struct ksym *ksym_search(long key)
 564 {
 565         int start = 0, end = sym_cnt;
 566         int result;
 567
 568         while (start < end) {
 569                 size_t mid = start + (end - start) / 2;
 570
 571                 result = key - syms[mid].addr;
 572                 if (result < 0)
 573                         end = mid;
 574                 else if (result > 0)
 575                         start = mid + 1;
 576                 else
 577                         return &syms[mid];
 578         }
 579
 580         if (start >= 1 && syms[start - 1].addr < key &&
 581             key < syms[start].addr)
 582                 /* valid ksym */
 583                 return &syms[start - 1];
 584
 585         /* out of range. return _stext */
 586         return &syms[0];
 587 }
 588
 589 int set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 590 {
 591         struct sockaddr_nl sa;
 592         int sock, seq = 0, len, ret = -1;
 593         char buf[4096];
 594         struct nlattr *nla, *nla_xdp;
 595         struct {
 596                 struct nlmsghdr  nh;
 597                 struct ifinfomsg ifinfo;
 598                 char             attrbuf[64];
 599         } req;
 600         struct nlmsghdr *nh;
 601         struct nlmsgerr *err;
 602
 603         memset(&sa, 0, sizeof(sa));
 604         sa.nl_family = AF_NETLINK;
 605
 606         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 607         if (sock < 0) {
 608                 printf("open netlink socket: %s\n", strerror(errno));
 609                 return -1;
 610         }
 611
 612         if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
 613                 printf("bind to netlink: %s\n", strerror(errno));
 614                 goto cleanup;
 615         }
 616
 617         memset(&req, 0, sizeof(req));
 618         req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
 619         req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
 620         req.nh.nlmsg_type = RTM_SETLINK;
 621         req.nh.nlmsg_pid = 0;
 622         req.nh.nlmsg_seq = ++seq;
 623         req.ifinfo.ifi_family = AF_UNSPEC;
 624         req.ifinfo.ifi_index = ifindex;
 625
 626         /* started nested attribute for XDP */
 627         nla = (struct nlattr *)(((char *)&req)
 628                                 + NLMSG_ALIGN(req.nh.nlmsg_len));
 629         nla->nla_type = NLA_F_NESTED | 43/*IFLA_XDP*/;
 630         nla->nla_len = NLA_HDRLEN;
 631
 632         /* add XDP fd */
 633         nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
 634         nla_xdp->nla_type = 1/*IFLA_XDP_FD*/;
 635         nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
 636         memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
 637         nla->nla_len += nla_xdp->nla_len;
 638
 639         /* if user passed in any flags, add those too */
 640         if (flags) {
 641                 nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
 642                 nla_xdp->nla_type = 3/*IFLA_XDP_FLAGS*/;
 643                 nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
 644                 memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
 645                 nla->nla_len += nla_xdp->nla_len;
 646         }
 647
 648         req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
 649
 650         if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
 651                 printf("send to netlink: %s\n", strerror(errno));
 652                 goto cleanup;
 653         }
 654
 655         len = recv(sock, buf, sizeof(buf), 0);
 656         if (len < 0) {
 657                 printf("recv from netlink: %s\n", strerror(errno));
 658                 goto cleanup;
 659         }
 660
 661         for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
 662              nh = NLMSG_NEXT(nh, len)) {
 663                 if (nh->nlmsg_pid != getpid()) {
 664                         printf("Wrong pid %d, expected %d\n",
 665                                nh->nlmsg_pid, getpid());
 666                         goto cleanup;
 667                 }
 668                 if (nh->nlmsg_seq != seq) {
 669                         printf("Wrong seq %d, expected %d\n",
 670                                nh->nlmsg_seq, seq);
 671                         goto cleanup;
 672                 }
 673                 switch (nh->nlmsg_type) {
 674                 case NLMSG_ERROR:
 675                         err = (struct nlmsgerr *)NLMSG_DATA(nh);
 676                         if (!err->error)
 677                                 continue;
 678                         printf("nlmsg error %s\n", strerror(-err->error));
 679                         goto cleanup;
 680                 case NLMSG_DONE:
 681                         break;
 682                 }
 683         }
 684
 685         ret = 0;
 686
 687 cleanup:
 688         close(sock);
 689         return ret;
 690 }