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authorFlorian Weimer <fweimer@redhat.com>2016-09-23 13:38:09 +0200
committerFlorian Weimer <fweimer@redhat.com>2016-09-23 13:38:09 +0200
commit67b73ea479073651a4ef7a967a02527a185e6e1b (patch)
tree4d7b67ecdeb5439b4c8f951f2204c9d4fda6683d /io
parent51364ff23e9760777bfea4eb9ac89c29a794074b (diff)
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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).
Diffstat (limited to 'io')
-rw-r--r--io/tst-open-tmpfile.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/io/tst-open-tmpfile.c b/io/tst-open-tmpfile.c
index 9af1875..9242d62 100644
--- a/io/tst-open-tmpfile.c
+++ b/io/tst-open-tmpfile.c
@@ -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)