tools/testing/selftests/bpf/prog_tests/deny_namespace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define _GNU_SOURCE
   3 #include <test_progs.h>
   4 #include "test_deny_namespace.skel.h"
   5 #include <sched.h>
   6 #include "cap_helpers.h"
   7 #include <stdio.h>
   8
   9 static int wait_for_pid(pid_t pid)
  10 {
  11         int status, ret;
  12
  13 again:
  14         ret = waitpid(pid, &status, 0);
  15         if (ret == -1) {
  16                 if (errno == EINTR)
  17                         goto again;
  18
  19                 return -1;
  20         }
  21
  22         if (!WIFEXITED(status))
  23                 return -1;
  24
  25         return WEXITSTATUS(status);
  26 }
  27
  28 /* negative return value -> some internal error
  29  * positive return value -> userns creation failed
  30  * 0                     -> userns creation succeeded
  31  */
  32 static int create_user_ns(void)
  33 {
  34         pid_t pid;
  35
  36         pid = fork();
  37         if (pid < 0)
  38                 return -1;
  39
  40         if (pid == 0) {
  41                 if (unshare(CLONE_NEWUSER))
  42                         _exit(EXIT_FAILURE);
  43                 _exit(EXIT_SUCCESS);
  44         }
  45
  46         return wait_for_pid(pid);
  47 }
  48
  49 static void test_userns_create_bpf(void)
  50 {
  51         __u32 cap_mask = 1ULL << CAP_SYS_ADMIN;
  52         __u64 old_caps = 0;
  53
  54         cap_enable_effective(cap_mask, &old_caps);
  55
  56         ASSERT_OK(create_user_ns(), "priv new user ns");
  57
  58         cap_disable_effective(cap_mask, &old_caps);
  59
  60         ASSERT_EQ(create_user_ns(), EPERM, "unpriv new user ns");
  61
  62         if (cap_mask & old_caps)
  63                 cap_enable_effective(cap_mask, NULL);
  64 }
  65
  66 static void test_unpriv_userns_create_no_bpf(void)
  67 {
  68         __u32 cap_mask = 1ULL << CAP_SYS_ADMIN;
  69         __u64 old_caps = 0;
  70
  71         cap_disable_effective(cap_mask, &old_caps);
  72
  73         ASSERT_OK(create_user_ns(), "no-bpf unpriv new user ns");
  74
  75         if (cap_mask & old_caps)
  76                 cap_enable_effective(cap_mask, NULL);
  77 }
  78
  79 void test_deny_namespace(void)
  80 {
  81         struct test_deny_namespace *skel = NULL;
  82         int err;
  83
  84         if (test__start_subtest("unpriv_userns_create_no_bpf"))
  85                 test_unpriv_userns_create_no_bpf();
  86
  87         skel = test_deny_namespace__open_and_load();
  88         if (!ASSERT_OK_PTR(skel, "skel load"))
  89                 goto close_prog;
  90
  91         err = test_deny_namespace__attach(skel);
  92         if (!ASSERT_OK(err, "attach"))
  93                 goto close_prog;
  94
  95         if (test__start_subtest("userns_create_bpf"))
  96                 test_userns_create_bpf();
  97
  98         test_deny_namespace__detach(skel);
  99
 100 close_prog:
 101         test_deny_namespace__destroy(skel);
 102 }