tools/testing/selftests/bpf/unpriv_helpers.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <stdbool.h>
   4 #include <stdlib.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <fcntl.h>
   9
  10 #include "unpriv_helpers.h"
  11
  12 static bool get_mitigations_off(void)
  13 {
  14         char cmdline[4096], *c;
  15         int fd, ret = false;
  16
  17         fd = open("/proc/cmdline", O_RDONLY);
  18         if (fd < 0) {
  19                 perror("open /proc/cmdline");
  20                 return false;
  21         }
  22
  23         if (read(fd, cmdline, sizeof(cmdline) - 1) < 0) {
  24                 perror("read /proc/cmdline");
  25                 goto out;
  26         }
  27
  28         cmdline[sizeof(cmdline) - 1] = '\0';
  29         for (c = strtok(cmdline, " \n"); c; c = strtok(NULL, " \n")) {
  30                 if (strncmp(c, "mitigations=off", strlen(c)))
  31                         continue;
  32                 ret = true;
  33                 break;
  34         }
  35 out:
  36         close(fd);
  37         return ret;
  38 }
  39
  40 bool get_unpriv_disabled(void)
  41 {
  42         bool disabled;
  43         char buf[2];
  44         FILE *fd;
  45
  46         fd = fopen("/proc/sys/" UNPRIV_SYSCTL, "r");
  47         if (fd) {
  48                 disabled = (fgets(buf, 2, fd) == buf && atoi(buf));
  49                 fclose(fd);
  50         } else {
  51                 perror("fopen /proc/sys/" UNPRIV_SYSCTL);
  52                 disabled = true;
  53         }
  54
  55         return disabled ? true : get_mitigations_off();
  56 }