// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
#include <sys/prctl.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include "trace_helpers.h"
#include "bpf_util.h"

#ifdef __mips__
#define MAX_ENTRIES  6000 /* MIPS n64 syscalls start at 5000 */
#else
#define MAX_ENTRIES  1024
#endif

/* 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)ARRAY_SIZE(filter),
                .filter = filter,
        };
        if (prctl(PR_SET_SECCOMP, 2, &prog))
                perror("prctl");
}

int main(int ac, char **argv)
{
        struct bpf_link *link = NULL;
        struct bpf_program *prog;
        struct bpf_object *obj;
        int key, fd, progs_fd;
        const char *section;
        char filename[256];
        FILE *f;

        snprintf(filename, sizeof(filename), "%s.bpf.o", argv[0]);
        obj = bpf_object__open_file(filename, NULL);
        if (libbpf_get_error(obj)) {
                fprintf(stderr, "ERROR: opening BPF object file failed\n");
                return 0;
        }

        prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
        if (!prog) {
                printf("finding a prog in obj file failed\n");
                goto cleanup;
        }

        /* load BPF program */
        if (bpf_object__load(obj)) {
                fprintf(stderr, "ERROR: loading BPF object file failed\n");
                goto cleanup;
        }

        link = bpf_program__attach(prog);
        if (libbpf_get_error(link)) {
                fprintf(stderr, "ERROR: bpf_program__attach failed\n");
                link = NULL;
                goto cleanup;
        }

        progs_fd = bpf_object__find_map_fd_by_name(obj, "progs");
        if (progs_fd < 0) {
                fprintf(stderr, "ERROR: finding a map in obj file failed\n");
                goto cleanup;
        }

        bpf_object__for_each_program(prog, obj) {
                section = bpf_program__section_name(prog);
                /* register only syscalls to PROG_ARRAY */
                if (sscanf(section, "kprobe/%d", &key) != 1)
                        continue;

                fd = bpf_program__fd(prog);
                bpf_map_update_elem(progs_fd, &key, &fd, BPF_ANY);
        }

        install_accept_all_seccomp();

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

        read_trace_pipe();

cleanup:
        bpf_link__destroy(link);
        bpf_object__close(obj);
        return 0;
}