tools/testing/selftests/bpf/test_dev_cgroup.c

   1 /* Copyright (c) 2017 Facebook
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <errno.h>
  12 #include <assert.h>
  13 #include <sys/time.h>
  14 #include <sys/resource.h>
  15
  16 #include <linux/bpf.h>
  17 #include <bpf/bpf.h>
  18 #include <bpf/libbpf.h>
  19
  20 #include "cgroup_helpers.h"
  21
  22 #define DEV_CGROUP_PROG "./dev_cgroup.o"
  23
  24 #define TEST_CGROUP "/test-bpf-based-device-cgroup/"
  25
  26 int main(int argc, char **argv)
  27 {
  28         struct rlimit limit  = { RLIM_INFINITY, RLIM_INFINITY };
  29         struct bpf_object *obj;
  30         int error = EXIT_FAILURE;
  31         int prog_fd, cgroup_fd;
  32         __u32 prog_cnt;
  33
  34         if (setrlimit(RLIMIT_MEMLOCK, &limit) < 0)
  35                 perror("Unable to lift memlock rlimit");
  36
  37         if (bpf_prog_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE,
  38                           &obj, &prog_fd)) {
  39                 printf("Failed to load DEV_CGROUP program\n");
  40                 goto out;
  41         }
  42
  43         if (setup_cgroup_environment()) {
  44                 printf("Failed to load DEV_CGROUP program\n");
  45                 goto err;
  46         }
  47
  48         /* Create a cgroup, get fd, and join it */
  49         cgroup_fd = create_and_get_cgroup(TEST_CGROUP);
  50         if (!cgroup_fd) {
  51                 printf("Failed to create test cgroup\n");
  52                 goto err;
  53         }
  54
  55         if (join_cgroup(TEST_CGROUP)) {
  56                 printf("Failed to join cgroup\n");
  57                 goto err;
  58         }
  59
  60         /* Attach bpf program */
  61         if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) {
  62                 printf("Failed to attach DEV_CGROUP program");
  63                 goto err;
  64         }
  65
  66         if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL,
  67                            &prog_cnt)) {
  68                 printf("Failed to query attached programs");
  69                 goto err;
  70         }
  71
  72         /* All operations with /dev/zero and and /dev/urandom are allowed,
  73          * everything else is forbidden.
  74          */
  75         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  76         assert(system("mknod /tmp/test_dev_cgroup_null c 1 3"));
  77         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  78
  79         /* /dev/zero is whitelisted */
  80         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  81         assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0);
  82         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  83
  84         assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0);
  85
  86         /* src is allowed, target is forbidden */
  87         assert(system("dd if=/dev/urandom of=/dev/full count=64"));
  88
  89         /* src is forbidden, target is allowed */
  90         assert(system("dd if=/dev/random of=/dev/zero count=64"));
  91
  92         error = 0;
  93         printf("test_dev_cgroup:PASS\n");
  94
  95 err:
  96         cleanup_cgroup_environment();
  97
  98 out:
  99         return error;
 100 }