src/kernel/linux/v4.19/samples/bpf/tracex5_user.c

// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <linux/bpf.h>
#include <unistd.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
#include <sys/prctl.h>
#include <bpf/bpf.h>
#include "bpf_load.h"
#include <sys/resource.h>

/* install fake seccomp program to enable seccomp code path inside the kernel,
 * so that our kprobe attached to seccomp_phase1() can be triggered
 */
static void install_accept_all_seccomp(void)
{
	struct sock_filter filter[] = {
		BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
	};
	struct sock_fprog prog = {
		.len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
		.filter = filter,
	};
	if (prctl(PR_SET_SECCOMP, 2, &prog))
		perror("prctl");
}

int main(int ac, char **argv)
{
	FILE *f;
	char filename[256];
	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};

	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
	setrlimit(RLIMIT_MEMLOCK, &r);

	if (load_bpf_file(filename)) {
		printf("%s", bpf_log_buf);
		return 1;
	}

	install_accept_all_seccomp();

	f = popen("dd if=/dev/zero of=/dev/null count=5", "r");
	(void) f;

	read_trace_pipe();

	return 0;
}