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 }
96
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