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 
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, 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 }
69