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

   1 /* Test for the memfd_create system call.
   2    Copyright (C) 2017-2024 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 <fcntl.h>
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <support/check.h>
  26 #include <support/support.h>
  27 #include <support/test-driver.h>
  28 #include <support/xunistd.h>
  29 #include <sys/mman.h>
  30
  31 /* Return true if the descriptor has the FD_CLOEXEC flag set.  */
  32 static bool
  33 is_cloexec (int fd)
  34 {
  35   int flags = fcntl (fd, F_GETFD);
  36   TEST_VERIFY (flags >= 0);
  37   return flags & FD_CLOEXEC;
  38 }
  39
  40 /* Return the seals set on FD.  */
  41 static int
  42 get_seals (int fd)
  43 {
  44   int flags = fcntl (fd, F_GET_SEALS);
  45   TEST_VERIFY (flags >= 0);
  46   return flags;
  47 }
  48
  49 /* Return true if the F_SEAL_SEAL flag is set on the descriptor.  */
  50 static bool
  51 is_sealed (int fd)
  52 {
  53   return get_seals (fd) & F_SEAL_SEAL;
  54 }
  55
  56 static int
  57 do_test (void)
  58 {
  59   /* Initialized by the first call to memfd_create to 0 (memfd_create
  60      unsupported) or 1 (memfd_create is implemented in the kernel).
  61      Subsequent iterations check that the success/failure state is
  62      consistent.  */
  63   int supported = -1;
  64
  65   for (int do_cloexec = 0; do_cloexec < 2; ++do_cloexec)
  66     for (int do_sealing = 0; do_sealing < 2; ++do_sealing)
  67       {
  68         int flags = 0;
  69         if (do_cloexec)
  70           flags |= MFD_CLOEXEC;
  71         if (do_sealing)
  72           flags |= MFD_ALLOW_SEALING;
  73         if  (test_verbose > 0)
  74           printf ("info: memfd_create with flags=0x%x\n", flags);
  75         int fd = memfd_create ("tst-memfd_create", flags);
  76         if (fd < 0)
  77           {
  78             if (errno == ENOSYS)
  79               {
  80                 if (supported < 0)
  81                   {
  82                     printf ("warning: memfd_create is unsupported\n");
  83                     supported = 0;
  84                     continue;
  85                   }
  86                 TEST_VERIFY (supported == 0);
  87                 continue;
  88               }
  89             else
  90               FAIL_EXIT1 ("memfd_create: %m");
  91           }
  92         if (supported < 0)
  93           supported = 1;
  94         TEST_VERIFY (supported > 0);
  95
  96         char *fd_path = xasprintf ("/proc/self/fd/%d", fd);
  97         char *link = xreadlink (fd_path);
  98         if (test_verbose > 0)
  99           printf ("info: memfd link: %s\n", link);
 100         TEST_VERIFY (strcmp (link, "memfd:tst-memfd_create (deleted)"));
 101         TEST_VERIFY (is_cloexec (fd) == do_cloexec);
 102         TEST_VERIFY (is_sealed (fd) == !do_sealing);
 103         if (do_sealing)
 104           {
 105             TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_WRITE) == 0);
 106             TEST_VERIFY (!is_sealed (fd));
 107             TEST_VERIFY (get_seals (fd) & F_SEAL_WRITE);
 108             TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_SEAL) == 0);
 109             TEST_VERIFY (is_sealed (fd));
 110           }
 111         xclose (fd);
 112         free (fd_path);
 113         free (link);
 114       }
 115
 116   if (supported == 0)
 117     return EXIT_UNSUPPORTED;
 118   return 0;
 119 }
 120
 121 #include <support/test-driver.c>