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
24#include "bpf_insn.h"
25#include "bpf_load.h"
26
27static int usage(const char *argv0)
28{
29	printf("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, ret, filter_id = 0;
36
37	if (argc < 3)
38		return usage(argv[0]);
39
40	cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
41	if (cg_fd < 0) {
42		printf("Failed to open cgroup path: '%s'\n", strerror(errno));
43		return EXIT_FAILURE;
44	}
45
46	if (load_bpf_file(argv[2]))
47		return EXIT_FAILURE;
48
49	printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
50
51	if (argc > 3)
52		filter_id = atoi(argv[3]);
53
54	if (filter_id >= prog_cnt) {
55		printf("Invalid program id; program not found in file\n");
56		return EXIT_FAILURE;
57	}
58
59	ret = bpf_prog_attach(prog_fd[filter_id], cg_fd,
60			      BPF_CGROUP_INET_SOCK_CREATE, 0);
61	if (ret < 0) {
62		printf("Failed to attach prog to cgroup: '%s'\n",
63		       strerror(errno));
64		return EXIT_FAILURE;
65	}
66
67	return EXIT_SUCCESS;
68}