Re: [PATCH v2 2/3] binderfs_test: switch from /dev to a unique per-test mountpoint

On Fri, Mar 13, 2020 at 04:24:19PM +0100, Christian Brauner wrote:

Unprivileged users will be able to create directories in there. The unprivileged test for /dev wouldn't have worked on most systems.

Cc: Kees Cook keescook@chromium.org: Signed-off-by: Christian Brauner christian.brauner@ubuntu.com

Reviewed-by: Kees Cook keescook@chromium.org

-Kees

---

/* v2 */

• Kees Cook keescook@chromium.org:
  • Switch to unique mountpoint through mkdtemp().

---

.../filesystems/binderfs/binderfs_test.c | 47 +++++++++---------- 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c index 0cfca65e095a..818eb49f8125 100644 --- a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c +++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c @@ -139,29 +139,25 @@ static int __do_binderfs_test(void) int fd, ret, saved_errno; size_t len; ssize_t wret;

• bool keep = false; struct binderfs_device device = { 0 }; struct binder_version version = { 0 };

• char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",

• device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
  

change_to_mountns();

• ret = mkdir("/dev/binderfs", 0755);
• if (ret < 0) {

• if (errno != EEXIST)
  

• 	ksft_exit_fail_msg(
  

• 		"%s - Failed to create binderfs mountpoint\n",
  

• 		strerror(errno));
  

• keep = true;
  

• }

• if (!mkdtemp(binderfs_mntpt))

• ksft_exit_fail_msg(
  

• 	"%s - Failed to create binderfs mountpoint\n",
  

• 	strerror(errno));
  

• ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);

• ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); if (ret < 0) { if (errno != ENODEV) ksft_exit_fail_msg("%s - Failed to mount binderfs\n", strerror(errno));

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  return 1; }

@@ -170,7 +166,8 @@ static int __do_binderfs_test(void) memcpy(device.name, "my-binder", strlen("my-binder"));

• fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);

• snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
• fd = open(device_path, O_RDONLY | O_CLOEXEC); if (fd < 0) ksft_exit_fail_msg( "%s - Failed to open binder-control device\n",

@@ -181,7 +178,7 @@ static int __do_binderfs_test(void) close(fd); errno = saved_errno; if (ret < 0) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg( "%s - Failed to allocate new binder device\n", strerror(errno));

@@ -194,9 +191,10 @@ static int __do_binderfs_test(void) /* binder device allocation test passed */ ksft_inc_pass_cnt();

• fd = open("/dev/binderfs/my-binder", O_CLOEXEC | O_RDONLY);

• snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
• fd = open(device_path, O_CLOEXEC | O_RDONLY); if (fd < 0) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg("%s - Failed to open my-binder device\n", strerror(errno)); }

@@ -206,7 +204,7 @@ static int __do_binderfs_test(void) close(fd); errno = saved_errno; if (ret < 0) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg( "%s - Failed to open perform BINDER_VERSION request\n", strerror(errno));

@@ -218,9 +216,9 @@ static int __do_binderfs_test(void) /* binder transaction with binderfs binder device passed */ ksft_inc_pass_cnt();

• ret = unlink("/dev/binderfs/my-binder");

• ret = unlink(device_path); if (ret < 0) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg("%s - Failed to delete binder device\n", strerror(errno)); }

@@ -228,12 +226,13 @@ static int __do_binderfs_test(void) /* binder device removal passed */ ksft_inc_pass_cnt();

• ret = unlink("/dev/binderfs/binder-control");

• snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
• ret = unlink(device_path); if (!ret) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg("Managed to delete binder-control device\n"); } else if (errno != EPERM) {

• keep ? : rmdir_protect_errno("/dev/binderfs");
  

• rmdir_protect_errno(binderfs_mntpt);
  

  ksft_exit_fail_msg( "%s - Failed to delete binder-control device but exited with unexpected error code\n", strerror(errno));

@@ -243,8 +242,8 @@ static int __do_binderfs_test(void) ksft_inc_xfail_cnt(); on_error:

• ret = umount2("/dev/binderfs", MNT_DETACH);
• keep ?: rmdir_protect_errno("/dev/binderfs");

• ret = umount2(binderfs_mntpt, MNT_DETACH);
• rmdir_protect_errno(binderfs_mntpt); if (ret < 0) ksft_exit_fail_msg("%s - Failed to unmount binderfs\n", strerror(errno));

-- 2.25.1