samples/bpf/test_cgrp2_sock2.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* eBPF example program:
   3  *
   4  * - Loads eBPF program
   5  *
   6  *   The eBPF program loads a filter from file and attaches the
   7  *   program to a cgroup using BPF_PROG_ATTACH
   8  */
   9
  10 #define _GNU_SOURCE
  11
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <stddef.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <assert.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <net/if.h>
  21 #include <linux/bpf.h>
  22 #include <bpf/bpf.h>
  23 #include <bpf/libbpf.h>
  24
  25 #include "bpf_insn.h"
  26
  27 static int usage(const char *argv0)
  28 {
  29         printf("Usage: %s cg-path filter-path [filter-id]\n", argv0);
  30         return EXIT_FAILURE;
  31 }
  32
  33 int main(int argc, char **argv)
  34 {
  35         int cg_fd, err, ret = EXIT_FAILURE, filter_id = 0, prog_cnt = 0;
  36         const char *link_pin_path = "/sys/fs/bpf/test_cgrp2_sock2";
  37         struct bpf_link *link = NULL;
  38         struct bpf_program *progs[2];
  39         struct bpf_program *prog;
  40         struct bpf_object *obj;
  41
  42         if (argc < 3)
  43                 return usage(argv[0]);
  44
  45         if (argc > 3)
  46                 filter_id = atoi(argv[3]);
  47
  48         cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
  49         if (cg_fd < 0) {
  50                 printf("Failed to open cgroup path: '%s'\n", strerror(errno));
  51                 return ret;
  52         }
  53
  54         obj = bpf_object__open_file(argv[2], NULL);
  55         if (libbpf_get_error(obj)) {
  56                 printf("ERROR: opening BPF object file failed\n");
  57                 return ret;
  58         }
  59
  60         bpf_object__for_each_program(prog, obj) {
  61                 progs[prog_cnt] = prog;
  62                 prog_cnt++;
  63         }
  64
  65         if (filter_id >= prog_cnt) {
  66                 printf("Invalid program id; program not found in file\n");
  67                 goto cleanup;
  68         }
  69
  70         /* load BPF program */
  71         if (bpf_object__load(obj)) {
  72                 printf("ERROR: loading BPF object file failed\n");
  73                 goto cleanup;
  74         }
  75
  76         link = bpf_program__attach_cgroup(progs[filter_id], cg_fd);
  77         if (libbpf_get_error(link)) {
  78                 printf("ERROR: bpf_program__attach failed\n");
  79                 link = NULL;
  80                 goto cleanup;
  81         }
  82
  83         err = bpf_link__pin(link, link_pin_path);
  84         if (err < 0) {
  85                 printf("ERROR: bpf_link__pin failed: %d\n", err);
  86                 goto cleanup;
  87         }
  88
  89         ret = EXIT_SUCCESS;
  90
  91 cleanup:
  92         bpf_link__destroy(link);
  93         bpf_object__close(obj);
  94         return ret;
  95 }