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
  15 #include <linux/bpf.h>
  16 #include <bpf/bpf.h>
  17 #include <bpf/libbpf.h>
  18
  19 #include "cgroup_helpers.h"
  20 #include "bpf_rlimit.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 bpf_object *obj;
  29         int error = EXIT_FAILURE;
  30         int prog_fd, cgroup_fd;
  31         __u32 prog_cnt;
  32
  33         if (bpf_prog_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE,
  34                           &obj, &prog_fd)) {
  35                 printf("Failed to load DEV_CGROUP program\n");
  36                 goto out;
  37         }
  38
  39         if (setup_cgroup_environment()) {
  40                 printf("Failed to load DEV_CGROUP program\n");
  41                 goto err;
  42         }
  43
  44         /* Create a cgroup, get fd, and join it */
  45         cgroup_fd = create_and_get_cgroup(TEST_CGROUP);
  46         if (!cgroup_fd) {
  47                 printf("Failed to create test cgroup\n");
  48                 goto err;
  49         }
  50
  51         if (join_cgroup(TEST_CGROUP)) {
  52                 printf("Failed to join cgroup\n");
  53                 goto err;
  54         }
  55
  56         /* Attach bpf program */
  57         if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) {
  58                 printf("Failed to attach DEV_CGROUP program");
  59                 goto err;
  60         }
  61
  62         if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL,
  63                            &prog_cnt)) {
  64                 printf("Failed to query attached programs");
  65                 goto err;
  66         }
  67
  68         /* All operations with /dev/zero and and /dev/urandom are allowed,
  69          * everything else is forbidden.
  70          */
  71         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  72         assert(system("mknod /tmp/test_dev_cgroup_null c 1 3"));
  73         assert(system("rm -f /tmp/test_dev_cgroup_null") == 0);
  74
  75         /* /dev/zero is whitelisted */
  76         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  77         assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0);
  78         assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0);
  79
  80         assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0);
  81
  82         /* src is allowed, target is forbidden */
  83         assert(system("dd if=/dev/urandom of=/dev/full count=64"));
  84
  85         /* src is forbidden, target is allowed */
  86         assert(system("dd if=/dev/random of=/dev/zero count=64"));
  87
  88         error = 0;
  89         printf("test_dev_cgroup:PASS\n");
  90
  91 err:
  92         cleanup_cgroup_environment();
  93
  94 out:
  95         return error;
  96 }