sysdeps/unix/sysv/linux/tst-pidfd_getpid.c

   1 /* Specific tests for Linux pidfd_getpid.
   2    Copyright (C) 2023-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sched.h>
  21 #include <stdlib.h>
  22 #include <support/check.h>
  23 #include <support/xunistd.h>
  24 #include <support/test-driver.h>
  25 #include <sys/pidfd.h>
  26 #include <sys/wait.h>
  27 #include <sys/mount.h>
  28
  29 static int
  30 do_test (void)
  31 {
  32   {
  33     /* The pidfd_getfd syscall was the last in the set of pidfd related
  34        syscalls added to the kernel.  Use pidfd_getfd to decide if this
  35        kernel has pidfd support that we can test.  */
  36     int r = pidfd_getfd (0, 0, 1);
  37     TEST_VERIFY_EXIT (r == -1);
  38     if (errno == ENOSYS)
  39       FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd, skipping test");
  40     if (errno == EPERM)
  41       FAIL_UNSUPPORTED ("kernel does not allow pidfd_getfd, skipping test");
  42   }
  43
  44   /* Check if pidfd_getpid returns EREMOTE for process not in current
  45      namespace.  */
  46   {
  47     pid_t child0 = xfork ();
  48     TEST_VERIFY_EXIT (child0 >= 0);
  49     if (child0 == 0)
  50       {
  51         /* Create another unrelated descriptor, so child2 will inherit the
  52            file descriptor.  */
  53         pid_t child1 = xfork ();
  54         TEST_VERIFY_EXIT (child1 >= 0);
  55         if (child1 == 0)
  56           _exit (0);
  57         int child1_pidfd = pidfd_open (child1, 0);
  58         TEST_VERIFY_EXIT (child1_pidfd != -1);
  59
  60         if (unshare (CLONE_NEWNS | CLONE_NEWUSER | CLONE_NEWPID) < 0)
  61           {
  62             /* Older kernels may not support all the options, or security
  63                policy may block this call.  */
  64             if (errno == EINVAL || errno == EPERM
  65                 || errno == ENOSPC || errno == EACCES)
  66               exit (EXIT_UNSUPPORTED);
  67             FAIL_EXIT1 ("unshare user/fs/pid failed: %m");
  68           }
  69
  70         if (mount (NULL, "/", NULL, MS_REC | MS_PRIVATE, 0) != 0)
  71           {
  72             /* This happens if we're trying to create a nested container,
  73                like if the build is running under podman, and we lack
  74                priviledges.  */
  75             if (errno  == EPERM)
  76               _exit (EXIT_UNSUPPORTED);
  77             else
  78               _exit (EXIT_FAILURE);
  79           }
  80
  81         pid_t child2 = xfork ();
  82         if (child2 > 0)
  83           {
  84             int status;
  85             xwaitpid (child2, &status, 0);
  86             TEST_VERIFY (WIFEXITED (status));
  87             xwaitpid (child1, &status, 0);
  88             TEST_VERIFY (WIFEXITED (status));
  89
  90             _exit (WEXITSTATUS (status));
  91           }
  92
  93         /* Now that we're pid 1 (effectively "root") we can mount /proc  */
  94         if (mount ("proc", "/proc", "proc", 0, NULL) != 0)
  95           {
  96             if (errno == EPERM)
  97               _exit (EXIT_UNSUPPORTED);
  98             else
  99               _exit (EXIT_FAILURE);
 100           }
 101
 102         TEST_COMPARE (pidfd_getpid (child1_pidfd), -1);
 103         TEST_COMPARE (errno, EREMOTE);
 104
 105         _exit (EXIT_SUCCESS);
 106       }
 107       int child0_pidfd = pidfd_open (child0, 0);
 108       TEST_VERIFY_EXIT (child0_pidfd != -1);
 109
 110       pid_t child0pid = pidfd_getpid (child0_pidfd);
 111
 112       siginfo_t info;
 113       TEST_COMPARE (waitid (P_PIDFD, child0_pidfd, &info, WEXITED), 0);
 114       if (info.si_status == EXIT_UNSUPPORTED)
 115         FAIL_UNSUPPORTED ("unable to unshare user/fs/pid");
 116       TEST_COMPARE (info.si_status, 0);
 117       TEST_COMPARE (info.si_code, CLD_EXITED);
 118       TEST_COMPARE (info.si_pid, child0pid);
 119   }
 120
 121   return 0;
 122 }
 123
 124 #include <support/test-driver.c>