1/* eBPF example program:
 2 *
 3 * - Loads eBPF program
 4 *
 5 *   The eBPF program loads a filter from file and attaches the
 6 *   program to a cgroup using BPF_PROG_ATTACH
 7 */
 8
 9#define _GNU_SOURCE
10
11#include <stdio.h>
12#include <stdlib.h>
13#include <stddef.h>
14#include <string.h>
15#include <unistd.h>
16#include <assert.h>
17#include <errno.h>
18#include <fcntl.h>
19#include <net/if.h>
20#include <linux/bpf.h>
21
22#include "libbpf.h"
23#include "bpf_load.h"
24
25static int usage(const char *argv0)
26{
27	printf("Usage: %s cg-path filter-path [filter-id]\n", argv0);
28	return EXIT_FAILURE;
29}
30
31int main(int argc, char **argv)
32{
33	int cg_fd, ret, filter_id = 0;
34
35	if (argc < 3)
36		return usage(argv[0]);
37
38	cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
39	if (cg_fd < 0) {
40		printf("Failed to open cgroup path: '%s'\n", strerror(errno));
41		return EXIT_FAILURE;
42	}
43
44	if (load_bpf_file(argv[2]))
45		return EXIT_FAILURE;
46
47	printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
48
49	if (argc > 3)
50		filter_id = atoi(argv[3]);
51
52	if (filter_id > prog_cnt) {
53		printf("Invalid program id; program not found in file\n");
54		return EXIT_FAILURE;
55	}
56
57	ret = bpf_prog_attach(prog_fd[filter_id], cg_fd,
58			      BPF_CGROUP_INET_SOCK_CREATE, 0);
59	if (ret < 0) {
60		printf("Failed to attach prog to cgroup: '%s'\n",
61		       strerror(errno));
62		return EXIT_FAILURE;
63	}
64
65	return EXIT_SUCCESS;
66}