tools/testing/selftests/bpf/test_dev_cgroup.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2017 Facebook
   3  */
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <errno.h>
   9 #include <assert.h>
  10 #include <sys/time.h>
  11
  12 #include <linux/bpf.h>
  13 #include <bpf/bpf.h>
  14 #include <bpf/libbpf.h>
  15
  16 #include "cgroup_helpers.h"
  17 #include "bpf_rlimit.h"
  18
  19 #define DEV_CGROUP_PROG "./dev_cgroup.o"
  20
  21 #define TEST_CGROUP "/test-bpf-based-device-cgroup/"
  22
  23 int main(int argc, char **argv)
  24 {
  25         struct bpf_object *obj;
  26         int error = EXIT_FAILURE;
  27         int prog_fd, cgroup_fd;
  28         __u32 prog_cnt;
  29
  30         if (bpf_prog_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE,
  31                           &obj, &prog_fd)) {
  32                 printf("Failed to load DEV_CGROUP program\n");
  33                 goto out;
  34         }
  35
  36         cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
  37         if (cgroup_fd < 0) {
  38                 printf("Failed to create test cgroup\n");
  39                 goto out;
  40         }
  41
  42         /* Attach bpf program */
  43         if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) {
  44                 printf("Failed to attach DEV_CGROUP program");
  45                 goto err;
  46         }
  47
  48         if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL,
  49                            &prog_cnt)) {
  50                 printf("Failed to query attached programs");
  51                 goto err;
  52         }
  53
  54         /* All operations with /dev/zero and and /dev/urandom are allowed,
  55          * everything else is forbidden.
  56          */
  57         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  58         assert(system("mknod /tmp/test_dev_cgroup_null c 1 3"));
  59         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  60
  61         /* /dev/zero is whitelisted */
  62         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  63         assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0);
  64         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  65
  66         assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0);
  67
  68         /* src is allowed, target is forbidden */
  69         assert(system("dd if=/dev/urandom of=/dev/full count=64"));
  70
  71         /* src is forbidden, target is allowed */
  72         assert(system("dd if=/dev/random of=/dev/zero count=64"));
  73
  74         error = 0;
  75         printf("test_dev_cgroup:PASS\n");
  76
  77 err:
  78         cleanup_cgroup_environment();
  79
  80 out:
  81         return error;
  82 }