[PATCH parted 1/2] libparted: Add test for /dev/mapper symlink issue

[Hans de Goede]

Sometimes libparted operates on device mapper files, with a path of
/dev/mapper/foo. With newer lvm versions /dev/mapper/foo is a symlink to
/dev/dm-#. However some storage administration programs (anaconda for
example) may do the following:
1) Create a ped_device for /dev/mapper/foo
2) ped_get_device resolves the symlink to /dev/dm-#, and the path
   in the PedDevice struct points to /dev/dm-#
3) The program does some things to lvm, causing the symlink to
   point to a different /dev/dm-# node
4) The program does something with the PedDevice, which results
   in an operation on the wrong device

Newer libparted versions do not suffer from this problem, as they
do not canonicalize device names under /dev/mapper. This test checks
for this bug.

* libparted/tests/symlink.c: New test which tests for this issue.
---
 libparted/tests/Makefile.am      |    5 +-
 libparted/tests/symlink.c        |  135 ++++++++++++++++++++++++++++++++++++++
 libparted/tests/t3000-symlink.sh |   29 ++++++++
 3 files changed, 167 insertions(+), 2 deletions(-)
 create mode 100644 libparted/tests/symlink.c
 create mode 100755 libparted/tests/t3000-symlink.sh

diff --git a/libparted/tests/Makefile.am b/libparted/tests/Makefile.am
index 2f63741..b433c83 100644
--- a/libparted/tests/Makefile.am
+++ b/libparted/tests/Makefile.am
@@ -3,9 +3,9 @@
 #
 # This file may be modified and/or distributed without restriction.
 
-TESTS = t1000-label.sh t2000-disk.sh
+TESTS = t1000-label.sh t2000-disk.sh t3000-symlink.sh
 EXTRA_DIST = $(TESTS)
-check_PROGRAMS = label disk
+check_PROGRAMS = label disk symlink
 AM_CFLAGS = $(WARN_CFLAGS) $(WERROR_CFLAGS)
 
 LDADD = \
@@ -19,6 +19,7 @@ AM_CPPFLAGS = \
 
 label_SOURCES = common.h common.c label.c
 disk_SOURCES  = common.h common.c disk.c
+symlink_SOURCES = common.h common.c symlink.c
 
 MAINTAINERCLEANFILES = Makefile.in
 
diff --git a/libparted/tests/symlink.c b/libparted/tests/symlink.c
new file mode 100644
index 0000000..f0bb46b
--- /dev/null
+++ b/libparted/tests/symlink.c
@@ -0,0 +1,135 @@
+/* Sometimes libparted operates on device mapper files, with a path of
+   /dev/mapper/foo. With newer lvm versions /dev/mapper/foo is a symlink to
+   /dev/dm-#. However some storage administration programs (anaconda for
+   example) may do the following:
+   1) Create a ped_device for /dev/mapper/foo
+   2) ped_get_device resolves the symlink to /dev/dm-#, and the path
+      in the PedDevice struct points to /dev/dm-#
+   3) The program does some things to lvm, causing the symlink to
+      point to a different /dev/dm-# node
+   4) The program does something with the PedDevice, which results
+      in an operation on the wrong device
+
+   Newer libparted versions do not suffer from this problem, as they
+   do not canonicalize device names under /dev/mapper. This test checks
+   for this bug. */
+
+#include <config.h>
+#include <unistd.h>
+
+#include <check.h>
+
+#include <parted/parted.h>
+
+#include "common.h"
+#include "progname.h"
+
+static char *temporary_disk;
+
+static void
+create_disk (void)
+{
+        temporary_disk = _create_disk (4096 * 1024);
+        fail_if (temporary_disk == NULL, "Failed to create temporary disk");
+}
+
+static void
+destroy_disk (void)
+{
+        unlink (temporary_disk);
+        free (temporary_disk);
+}
+
+START_TEST (test_symlink)
+{
+        char cwd[256], ln[256] = "/dev/mapper/parted-test-XXXXXX";
+
+        if (!getcwd(cwd, sizeof(cwd))) {
+                fail("Could not get cwd");
+                return;
+        }
+
+        /* Create a symlink under /dev/mapper to our
+           temporary disk */
+        int tmp_fd = mkstemp(ln);
+        if (tmp_fd == -1) {
+                fail("Could not create tempfile");
+                return;
+        }
+
+        /* There is a temp file vulnerability symlink attack possibility
+           here, but as /dev/mapper is root owned this is a non issue */
+        close (tmp_fd);
+        unlink (ln);
+        char temp_disk_path[256];
+        snprintf (temp_disk_path, sizeof(temp_disk_path), "%s/%s", cwd,
+                  temporary_disk);
+        int res = symlink (temp_disk_path, ln);
+        if (res) {
+                fail("could not create symlink");
+                return;
+        }
+
+        PedDevice* dev = ped_device_get (ln);
+        if (dev == NULL)
+                goto exit_unlink_ln;
+
+        /* Create a second temporary_disk */
+        char *temporary_disk2 = _create_disk (4096 * 1024);
+        if (temporary_disk2 == NULL) {
+                fail ("Failed to create 2nd temporary disk");
+                goto exit_destroy_dev;
+        }
+
+        /* Remove first temporary disk, and make temporary_disk point to
+           temporary_disk2 (for destroy_disk()). */
+        unlink (temporary_disk);
+        free (temporary_disk);
+        temporary_disk = temporary_disk2;
+
+        /* Update symlink to point to our new / second temporary disk */
+        unlink (ln);
+        snprintf (temp_disk_path, sizeof(temp_disk_path), "%s/%s", cwd,
+                  temporary_disk);
+        res = symlink (temp_disk_path, ln);
+        if (res) {
+                fail("could not create 2nd symlink");
+                goto exit_destroy_dev;
+        }
+
+        /* Do something to our PedDevice, if the symlink was resolved,
+           instead of remembering the /dev/mapper/foo name, this will fail */
+        ped_disk_clobber (dev);
+
+exit_destroy_dev:
+        ped_device_destroy (dev);
+exit_unlink_ln:
+        unlink (ln);
+}
+END_TEST
+
+int
+main (int argc, char **argv)
+{
+        set_program_name (argv[0]);
+        int number_failed;
+        Suite* suite = suite_create ("Symlink");
+        TCase* tcase_symlink = tcase_create ("/dev/mapper symlink");
+
+        /* Fail when an exception is raised */
+        ped_exception_set_handler (_test_exception_handler);
+
+        tcase_add_checked_fixture (tcase_symlink, create_disk, destroy_disk);
+        tcase_add_test (tcase_symlink, test_symlink);
+        /* Disable timeout for this test */
+        tcase_set_timeout (tcase_symlink, 0);
+        suite_add_tcase (suite, tcase_symlink);
+
+        SRunner* srunner = srunner_create (suite);
+        srunner_run_all (srunner, CK_VERBOSE);
+
+        number_failed = srunner_ntests_failed (srunner);
+        srunner_free (srunner);
+
+        return (number_failed == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/libparted/tests/t3000-symlink.sh b/libparted/tests/t3000-symlink.sh
new file mode 100755
index 0000000..9c64833
--- /dev/null
+++ b/libparted/tests/t3000-symlink.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+# Copyright (C) 2007-2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+test_description='run the /dev/mapper symlink test'
+
+# Need root privileges to create a symlink under /dev/mapper.
+privileges_required_=1
+
+: ${top_srcdir=../..}
+. "$top_srcdir/tests/test-lib.sh"
+
+test_expect_success \
+    'run the actual tests' 'symlink'
+
+test_done
-- 
1.7.0.1