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
23#include "libbpf.h"
24#include "bpf_load.h"
25
26static int usage(const char *argv0)
27{
28	printf("Usage: %s cg-path filter-path [filter-id]\n", argv0);
29	return EXIT_FAILURE;
30}
31
32int main(int argc, char **argv)
33{
34	int cg_fd, ret, filter_id = 0;
35
36	if (argc < 3)
37		return usage(argv[0]);
38
39	cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
40	if (cg_fd < 0) {
41		printf("Failed to open cgroup path: '%s'\n", strerror(errno));
42		return EXIT_FAILURE;
43	}
44
45	if (load_bpf_file(argv[2]))
46		return EXIT_FAILURE;
47
48	printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
49
50	if (argc > 3)
51		filter_id = atoi(argv[3]);
52
53	if (filter_id > prog_cnt) {
54		printf("Invalid program id; program not found in file\n");
55		return EXIT_FAILURE;
56	}
57
58	ret = bpf_prog_attach(prog_fd[filter_id], cg_fd,
59			      BPF_CGROUP_INET_SOCK_CREATE, 0);
60	if (ret < 0) {
61		printf("Failed to attach prog to cgroup: '%s'\n",
62		       strerror(errno));
63		return EXIT_FAILURE;
64	}
65
66	return EXIT_SUCCESS;
67}