samples/bpf/tracex5_user.c

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