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
27static int usage(const char *argv0)
28{
29 printf(format: "Usage: %s cg-path filter-path [filter-id]\n", argv0);
30 return EXIT_FAILURE;
31}
32
33int 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(argv0: argv[0]);
44
45 if (argc > 3)
46 filter_id = atoi(nptr: argv[3]);
47
48 cg_fd = open(file: argv[1], O_DIRECTORY | O_RDONLY);
49 if (cg_fd < 0) {
50 printf(format: "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(format: "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(format: "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(format: "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(format: "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(format: "ERROR: bpf_link__pin failed: %d\n", err);
86 goto cleanup;
87 }
88
89 ret = EXIT_SUCCESS;
90
91cleanup:
92 bpf_link__destroy(link);
93 bpf_object__close(obj);
94 return ret;
95}
96

source code of linux/samples/bpf/test_cgrp2_sock2.c