xref: /openbmc/linux/samples/bpf/tracex5_user.c (revision ae213c44)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <stdio.h>
3 #include <linux/bpf.h>
4 #include <unistd.h>
5 #include <linux/filter.h>
6 #include <linux/seccomp.h>
7 #include <sys/prctl.h>
8 #include <bpf/bpf.h>
9 #include "bpf_load.h"
10 #include <sys/resource.h>
11 
12 /* install fake seccomp program to enable seccomp code path inside the kernel,
13  * so that our kprobe attached to seccomp_phase1() can be triggered
14  */
15 static void install_accept_all_seccomp(void)
16 {
17 	struct sock_filter filter[] = {
18 		BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
19 	};
20 	struct sock_fprog prog = {
21 		.len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
22 		.filter = filter,
23 	};
24 	if (prctl(PR_SET_SECCOMP, 2, &prog))
25 		perror("prctl");
26 }
27 
28 int main(int ac, char **argv)
29 {
30 	FILE *f;
31 	char filename[256];
32 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
33 
34 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
35 	setrlimit(RLIMIT_MEMLOCK, &r);
36 
37 	if (load_bpf_file(filename)) {
38 		printf("%s", bpf_log_buf);
39 		return 1;
40 	}
41 
42 	install_accept_all_seccomp();
43 
44 	f = popen("dd if=/dev/zero of=/dev/null count=5", "r");
45 	(void) f;
46 
47 	read_trace_pipe();
48 
49 	return 0;
50 }
51