99 lines · c
1// SPDX-License-Identifier: GPL-2.02#include <stdio.h>3#include <stdlib.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/libbpf.h>10#include "trace_helpers.h"11#include "bpf_util.h"12 13#ifdef __mips__14#define MAX_ENTRIES 6000 /* MIPS n64 syscalls start at 5000 */15#else16#define MAX_ENTRIES 102417#endif18 19/* install fake seccomp program to enable seccomp code path inside the kernel,20 * so that our kprobe attached to seccomp_phase1() can be triggered21 */22static void install_accept_all_seccomp(void)23{24 struct sock_filter filter[] = {25 BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),26 };27 struct sock_fprog prog = {28 .len = (unsigned short)ARRAY_SIZE(filter),29 .filter = filter,30 };31 if (prctl(PR_SET_SECCOMP, 2, &prog))32 perror("prctl");33}34 35int main(int ac, char **argv)36{37 struct bpf_link *link = NULL;38 struct bpf_program *prog;39 struct bpf_object *obj;40 int key, fd, progs_fd;41 const char *section;42 char filename[256];43 FILE *f;44 45 snprintf(filename, sizeof(filename), "%s.bpf.o", argv[0]);46 obj = bpf_object__open_file(filename, NULL);47 if (libbpf_get_error(obj)) {48 fprintf(stderr, "ERROR: opening BPF object file failed\n");49 return 0;50 }51 52 prog = bpf_object__find_program_by_name(obj, "bpf_prog1");53 if (!prog) {54 printf("finding a prog in obj file failed\n");55 goto cleanup;56 }57 58 /* load BPF program */59 if (bpf_object__load(obj)) {60 fprintf(stderr, "ERROR: loading BPF object file failed\n");61 goto cleanup;62 }63 64 link = bpf_program__attach(prog);65 if (libbpf_get_error(link)) {66 fprintf(stderr, "ERROR: bpf_program__attach failed\n");67 link = NULL;68 goto cleanup;69 }70 71 progs_fd = bpf_object__find_map_fd_by_name(obj, "progs");72 if (progs_fd < 0) {73 fprintf(stderr, "ERROR: finding a map in obj file failed\n");74 goto cleanup;75 }76 77 bpf_object__for_each_program(prog, obj) {78 section = bpf_program__section_name(prog);79 /* register only syscalls to PROG_ARRAY */80 if (sscanf(section, "kprobe/%d", &key) != 1)81 continue;82 83 fd = bpf_program__fd(prog);84 bpf_map_update_elem(progs_fd, &key, &fd, BPF_ANY);85 }86 87 install_accept_all_seccomp();88 89 f = popen("dd if=/dev/zero of=/dev/null count=5", "r");90 (void) f;91 92 read_trace_pipe();93 94cleanup:95 bpf_link__destroy(link);96 bpf_object__close(obj);97 return 0;98}99