samples/bpf/tracex5_user.c

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