posix/tst-execveat.c

   1 /* Test execveat at the various corner cases.
   2    Copyright (C) 2021-2023 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 <fcntl.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <sys/types.h>
  23 #include <dirent.h>
  24 #include <support/check.h>
  25 #include <support/support.h>
  26 #include <support/temp_file.h>
  27 #include <support/xdlfcn.h>
  28 #include <support/xstdio.h>
  29 #include <support/xunistd.h>
  30 #include <wait.h>
  31 #include <support/test-driver.h>
  32
  33 int
  34 call_execveat (int fd, const char *pathname, int flags, int expected_fail,
  35                int num)
  36 {
  37   char *envp[] = { (char *) "FOO=3", NULL };
  38   char *argv[] = { (char *) "sh", (char *) "-c", (char *) "exit $FOO", NULL };
  39   pid_t pid;
  40   int status;
  41
  42   if (test_verbose > 0)
  43     printf ("call line number: %d\n", num);
  44
  45   pid = xfork ();
  46   if (pid == 0)
  47     {
  48       TEST_COMPARE (execveat (fd, pathname, argv, envp, flags), -1);
  49       if (errno == ENOSYS)
  50         exit (EXIT_UNSUPPORTED);
  51       else if (errno == expected_fail)
  52         {
  53           if (test_verbose > 0)
  54             printf ("expected fail: errno %d\n", errno);
  55           _exit (0);
  56         }
  57       else
  58         FAIL_EXIT1 ("execveat failed: %m (%d)", errno);
  59     }
  60   xwaitpid (pid, &status, 0);
  61
  62   if (!WIFEXITED (status))
  63     FAIL_RET ("child hasn't exited normally");
  64
  65   if (WIFEXITED (status))
  66     {
  67       if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
  68         FAIL_UNSUPPORTED ("execveat is unimplemented");
  69       else if (expected_fail != 0)
  70         TEST_COMPARE (WEXITSTATUS (status), 0);
  71       else
  72         TEST_COMPARE (WEXITSTATUS (status), 3);
  73     }
  74   return 0;
  75 }
  76
  77 static int
  78 do_test (void)
  79 {
  80   DIR *dirp;
  81   int fd;
  82 #ifdef O_PATH
  83   int fd_out;
  84   char *tmp_dir, *symlink_name, *tmp_sh;
  85   struct stat64 st;
  86 #endif
  87
  88   dirp = opendir ("/bin");
  89   if (dirp == NULL)
  90     FAIL_EXIT1 ("failed to open /bin");
  91   fd = dirfd (dirp);
  92
  93   /* Call execveat for various fd/pathname combinations.  */
  94
  95   /* Check the pathname relative to a valid dirfd.  */
  96   call_execveat (fd, "sh", 0, 0, __LINE__);
  97   xchdir ("/bin");
  98   /* Use the special value AT_FDCWD as dirfd. Quoting open(2):
  99      If pathname is relative and dirfd is the special value AT_FDCWD, then
 100      pathname is interpreted relative to the current working directory of
 101      the calling process.  */
 102   call_execveat (AT_FDCWD, "sh", 0, 0, __LINE__);
 103   xclose (fd);
 104 #ifdef O_PATH
 105   /* Check the pathname relative to a valid dirfd with O_PATH.  */
 106   fd = xopen ("/bin", O_PATH | O_DIRECTORY, O_RDONLY);
 107   call_execveat (fd, "sh", 0, 0, __LINE__);
 108   xclose (fd);
 109
 110   /* Check absolute pathname, dirfd should be ignored.  */
 111   call_execveat (AT_FDCWD, "/bin/sh", 0, 0, __LINE__);
 112   fd = xopen ("/usr", O_PATH | O_DIRECTORY, 0);
 113   /* Same check for absolute pathname, but with input file descriptor
 114      opened with different flags.  The dirfd should be ignored.  */
 115   call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
 116   xclose (fd);
 117 #endif
 118
 119   fd = xopen ("/usr", O_RDONLY, 0);
 120   /* Same check for absolute pathname, but with input file descriptor
 121      opened with different flags.  The dirfd should be ignored.  */
 122   call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
 123   xclose (fd);
 124
 125   fd = xopen ("/bin/sh", O_RDONLY, 0);
 126   /* Check relative pathname, where dirfd does not point to a directory.  */
 127   call_execveat (fd, "sh", 0, ENOTDIR, __LINE__);
 128   /* Check absolute pathname, but dirfd is a regular file.  The dirfd
 129      should be ignored.  */
 130   call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
 131   xclose (fd);
 132
 133 #ifdef O_PATH
 134   /* Quoting open(2): O_PATH
 135      Obtain a file descriptor that can be used for two purposes: to
 136      indicate a location in the filesystem tree and to perform
 137      operations that act purely at the file descriptor level.  */
 138   fd = xopen ("/bin/sh", O_PATH, 0);
 139   /* Check the empty pathname.  Dirfd is a regular file with O_PATH.  */
 140   call_execveat (fd, "", 0, ENOENT, __LINE__);
 141   /* Same check for an empty pathname, but with AT_EMPTY_PATH flag.
 142      Quoting open(2):
 143      If oldpath is an empty string, create a link to the file referenced
 144      by olddirfd (which may have been obtained using the open(2) O_PATH flag. */
 145   call_execveat (fd, "", AT_EMPTY_PATH, 0, __LINE__);
 146   call_execveat (fd, "", AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW, 0, __LINE__);
 147   xclose (fd);
 148
 149   /* Create a temporary directory "tmp_dir" and create a symbolik link tmp_sh
 150      pointing to /bin/sh inside the tmp_dir. Open dirfd as a symbolic link.  */
 151   tmp_dir = support_create_temp_directory ("tst-execveat_dir");
 152   symlink_name = xasprintf ("%s/symlink", tmp_dir);
 153   xsymlink ("tmp_sh", symlink_name);
 154   add_temp_file (symlink_name);
 155   tmp_sh = xasprintf ("%s/tmp_sh", tmp_dir);
 156   add_temp_file (tmp_sh);
 157   fd_out = xopen (symlink_name, O_CREAT | O_WRONLY, 0);
 158   xstat ("/bin/sh", &st);
 159   fd = xopen ("/bin/sh", O_RDONLY, 0);
 160   xcopy_file_range (fd, 0, fd_out, 0, st.st_size, 0);
 161   xfchmod (fd_out, 0700);
 162   xclose (fd);
 163   xclose (fd_out);
 164   fd_out = xopen (symlink_name, O_PATH, 0);
 165
 166  /* Check the empty pathname. Dirfd is a symbolic link.  */
 167   call_execveat (fd_out, "", 0, ENOENT, __LINE__);
 168   call_execveat (fd_out, "", AT_EMPTY_PATH, 0, __LINE__);
 169   call_execveat (fd_out, "", AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW, 0,
 170                  __LINE__);
 171   xclose (fd_out);
 172   free (symlink_name);
 173   free (tmp_sh);
 174   free (tmp_dir);
 175 #endif
 176
 177   /* Call execveat with closed fd, we expect this to fail with EBADF.  */
 178   call_execveat (fd, "sh", 0, EBADF, __LINE__);
 179   /* Call execveat with closed fd, we expect this to pass because the pathname is
 180      absolute.  */
 181   call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
 182
 183   return 0;
 184 }
 185
 186 #include <support/test-driver.c>