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tst-open-tmpfile: Add checks for open64, openat64, linkat 

The /proc/self/fd approach is expected to work for all users
(with and without CAP_DAC_READ_SEARCH).
This commit is contained in:
Florian Weimer 2016-09-23 13:38:09 +02:00
parent 51364ff23e
commit 67b73ea479
2 changed files with 111 additions and 0 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2016-09-23 Florian Weimer <fweimer@redhat.com>
* io/tst-open-tmpfile.c (wrap_open64, wrap_openat64)
(get_random_name): New functions.
(check_wrapper_flags_mode): Use linkat to give the new file a name
determined by get_random_name.
(do_test): Add calls to test open64 and openat64.
2016-09-23 Florian Weimer <fweimer@redhat.com>
* test-skeleton.c: Remove #include <stdarg.h>.

103
io/tst-open-tmpfile.c
View File

@ -64,6 +64,34 @@ wrap_openat (const char *path, int flags, mode_t mode)
return ret;
}
/* Error-checking wrapper for the open64 function, compatible with the
wrapper_func type. */
static int
wrap_open64 (const char *path, int flags, mode_t mode)
{
int ret = open64 (path, flags, mode);
if (ret < 0)
{
printf ("error: open64 (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
exit (1);
}
return ret;
}
/* Error-checking wrapper for the openat64 function, compatible with the
wrapper_func type. */
static int
wrap_openat64 (const char *path, int flags, mode_t mode)
{
int ret = openat64 (AT_FDCWD, path, flags, mode);
if (ret < 0)
{
printf ("error: openat64 (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
exit (1);
}
return ret;
}
/* Return true if FD is flagged as deleted in /proc/self/fd, false if
not. */
static bool
@ -97,6 +125,32 @@ is_file_deteted (int fd)
deleted, strlen (deleted)) == 0;
}
/* Obtain a file name which is difficult to guess. */
static char *
get_random_name (void)
{
unsigned long long bytes[2];
int random_device = open ("/dev/urandom", O_RDONLY);
if (random_device < 0)
{
printf ("error: open (\"/dev/urandom\"): %m\n");
exit (1);
}
ssize_t ret = read (random_device, bytes, sizeof (bytes));
if (ret < 0)
{
printf ("error: read (\"/dev/urandom\"): %m\n");
exit (1);
}
if (ret != sizeof (bytes))
{
printf ("error: short read from /dev/urandom: %zd\n", ret);
exit (1);
}
close (random_device);
return xasprintf ("tst-open-tmpfile-%08llx%08llx.tmp", bytes[0], bytes[1]);
}
/* Check open/openat (as specified by OP and WRAPPER) with a specific
PATH/FLAGS/MODE combination. */
static void
@ -127,6 +181,53 @@ check_wrapper_flags_mode (const char *op, wrapper_func wrapper,
exit (1);
}
/* Check that the file can be turned into a regular file with
linkat. Open a file descriptor for the directory at PATH. Use
AT_FDCWD if PATH is ".", to exercise that functionality as
well. */
int path_fd;
if (strcmp (path, ".") == 0)
path_fd = AT_FDCWD;
else
{
path_fd = open (path, O_RDONLY | O_DIRECTORY);
if (path_fd < 0)
{
printf ("error: open (\"%s\"): %m\n", path);
exit (1);
}
}
/* Use a hard-to-guess name for the new directory entry. */
char *new_name = get_random_name ();
/* linkat does not require privileges if the path in /proc/self/fd
is used. */
char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
if (linkat (AT_FDCWD, proc_fd_path, path_fd, new_name,
AT_SYMLINK_FOLLOW) == 0)
{
if (unlinkat (path_fd, new_name, 0) != 0 && errno != ENOENT)
{
printf ("error: unlinkat (\"%s/%s\"): %m\n", path, new_name);
exit (1);
}
}
else
{
/* linkat failed. This is expected if O_EXCL was specified. */
if ((flags & O_EXCL) == 0)
{
printf ("error: linkat failed after %s (\"%s\", 0x%x, 0%03o): %m\n",
op, path, flags, mode);
exit (1);
}
}
free (proc_fd_path);
free (new_name);
if (path_fd != AT_FDCWD)
close (path_fd);
close (fd);
}
@ -197,6 +298,8 @@ do_test (void)
supported = true;
check_wrapper ("open", wrap_open, paths[i]);
check_wrapper ("openat", wrap_openat, paths[i]);
check_wrapper ("open64", wrap_open64, paths[i]);
check_wrapper ("openat64", wrap_openat64, paths[i]);
}
if (!supported)