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Commit 4a44a19b authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

mnt: Update unprivileged remount test 



- MNT_NODEV should be irrelevant except when reading back mount flags,
  no longer specify MNT_NODEV on remount.

- Test MNT_NODEV on devpts where it is meaningful even for unprivileged mounts.

- Add a test to verify that remount of a prexisting mount with the same flags
  is allowed and does not change those flags.

- Cleanup up the definitions of MS_REC, MS_RELATIME, MS_STRICTATIME that are used
  when the code is built in an environment without them.

- Correct the test error messages when tests fail.  There were not 5 tests
  that tested MS_RELATIME.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 3e186641

tools/testing/selftests/mount/unprivileged-remount-test.c

+142 −30
Original line number Original line Diff line number Diff line
@@ -6,6 +6,8 @@ 
#include <sys/types.h>

#include <sys/types.h>

#include <sys/mount.h>

#include <sys/mount.h>

#include <sys/wait.h>

#include <sys/wait.h>

#include <sys/vfs.h>

#include <sys/statvfs.h>

#include <stdlib.h>

#include <stdlib.h>

#include <unistd.h>

#include <unistd.h>

#include <fcntl.h>

#include <fcntl.h>
@@ -32,6 +34,9 @@ 
# define CLONE_NEWPID 0x20000000

# define CLONE_NEWPID 0x20000000

#endif

#endif





#ifndef MS_REC

# define MS_REC 16384

#endif

#ifndef MS_RELATIME

#ifndef MS_RELATIME

# define MS_RELATIME (1 << 21)

# define MS_RELATIME (1 << 21)

#endif

#endif
@@ -87,6 +92,45 @@ static void write_file(char *filename, char *fmt, ...) 
	}

	}

}

}





static int read_mnt_flags(const char *path)

{

	int ret;

	struct statvfs stat;

	int mnt_flags;



	ret = statvfs(path, &stat);

	if (ret != 0) {

		die("statvfs of %s failed: %s\n",

			path, strerror(errno));

	}

	if (stat.f_flag & ~(ST_RDONLY | ST_NOSUID | ST_NODEV | \

			ST_NOEXEC | ST_NOATIME | ST_NODIRATIME | ST_RELATIME | \

			ST_SYNCHRONOUS | ST_MANDLOCK)) {

		die("Unrecognized mount flags\n");

	}

	mnt_flags = 0;

	if (stat.f_flag & ST_RDONLY)

		mnt_flags |= MS_RDONLY;

	if (stat.f_flag & ST_NOSUID)

		mnt_flags |= MS_NOSUID;

	if (stat.f_flag & ST_NODEV)

		mnt_flags |= MS_NODEV;

	if (stat.f_flag & ST_NOEXEC)

		mnt_flags |= MS_NOEXEC;

	if (stat.f_flag & ST_NOATIME)

		mnt_flags |= MS_NOATIME;

	if (stat.f_flag & ST_NODIRATIME)

		mnt_flags |= MS_NODIRATIME;

	if (stat.f_flag & ST_RELATIME)

		mnt_flags |= MS_RELATIME;

	if (stat.f_flag & ST_SYNCHRONOUS)

		mnt_flags |= MS_SYNCHRONOUS;

	if (stat.f_flag & ST_MANDLOCK)

		mnt_flags |= ST_MANDLOCK;



	return mnt_flags;

}



static void create_and_enter_userns(void)

static void create_and_enter_userns(void)

{

{

	uid_t uid;

	uid_t uid;
@@ -118,7 +162,8 @@ static void create_and_enter_userns(void) 
}

}





static

static

bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags)

bool test_unpriv_remount(const char *fstype, const char *mount_options,

			 int mount_flags, int remount_flags, int invalid_flags)

{

{

	pid_t child;

	pid_t child;
@@ -151,8 +196,10 @@ bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags) 
			strerror(errno));

			strerror(errno));

	}

	}





	if (mount("testing", "/tmp", "ramfs", mount_flags, NULL) != 0) {

	if (mount("testing", "/tmp", fstype, mount_flags, mount_options) != 0) {

		die("mount of /tmp failed: %s\n",

		die("mount of %s with options '%s' on /tmp failed: %s\n",

		    fstype,

		    mount_options? mount_options : "",

		    strerror(errno));

		    strerror(errno));

	}

	}
@@ -181,62 +228,127 @@ bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags) 




static bool test_unpriv_remount_simple(int mount_flags)

static bool test_unpriv_remount_simple(int mount_flags)

{

{

	return test_unpriv_remount(mount_flags, mount_flags, 0);

	return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags, 0);

}

}





static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags)

static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags)

{

{

	return test_unpriv_remount(mount_flags, mount_flags, invalid_flags);

	return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags,

				   invalid_flags);

}



static bool test_priv_mount_unpriv_remount(void)

{

	pid_t child;

	int ret;

	const char *orig_path = "/dev";

	const char *dest_path = "/tmp";

	int orig_mnt_flags, remount_mnt_flags;



	child = fork();

	if (child == -1) {

		die("fork failed: %s\n",

			strerror(errno));

	}

	if (child != 0) { /* parent */

		pid_t pid;

		int status;

		pid = waitpid(child, &status, 0);

		if (pid == -1) {

			die("waitpid failed: %s\n",

				strerror(errno));

		}

		if (pid != child) {

			die("waited for %d got %d\n",

				child, pid);

		}

		if (!WIFEXITED(status)) {

			die("child did not terminate cleanly\n");

		}

		return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;

	}



	orig_mnt_flags = read_mnt_flags(orig_path);



	create_and_enter_userns();

	ret = unshare(CLONE_NEWNS);

	if (ret != 0) {

		die("unshare(CLONE_NEWNS) failed: %s\n",

			strerror(errno));

	}



	ret = mount(orig_path, dest_path, "bind", MS_BIND | MS_REC, NULL);

	if (ret != 0) {

		die("recursive bind mount of %s onto %s failed: %s\n",

			orig_path, dest_path, strerror(errno));

	}



	ret = mount(dest_path, dest_path, "none",

		    MS_REMOUNT | MS_BIND | orig_mnt_flags , NULL);

	if (ret != 0) {

		/* system("cat /proc/self/mounts"); */

		die("remount of /tmp failed: %s\n",

		    strerror(errno));

	}



	remount_mnt_flags = read_mnt_flags(dest_path);

	if (orig_mnt_flags != remount_mnt_flags) {

		die("Mount flags unexpectedly changed during remount of %s originally mounted on %s\n",

			dest_path, orig_path);

	}

	exit(EXIT_SUCCESS);

}

}





int main(int argc, char **argv)

int main(int argc, char **argv)

{

{

	if (!test_unpriv_remount_simple(MS_RDONLY|MS_NODEV)) {

	if (!test_unpriv_remount_simple(MS_RDONLY)) {

		die("MS_RDONLY malfunctions\n");

		die("MS_RDONLY malfunctions\n");

	}

	}

	if (!test_unpriv_remount_simple(MS_NODEV)) {

	if (!test_unpriv_remount("devpts", "newinstance", MS_NODEV, MS_NODEV, 0)) {

		die("MS_NODEV malfunctions\n");

		die("MS_NODEV malfunctions\n");

	}

	}

	if (!test_unpriv_remount_simple(MS_NOSUID|MS_NODEV)) {

	if (!test_unpriv_remount_simple(MS_NOSUID)) {

		die("MS_NOSUID malfunctions\n");

		die("MS_NOSUID malfunctions\n");

	}

	}

	if (!test_unpriv_remount_simple(MS_NOEXEC|MS_NODEV)) {

	if (!test_unpriv_remount_simple(MS_NOEXEC)) {

		die("MS_NOEXEC malfunctions\n");

		die("MS_NOEXEC malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_RELATIME,

				       MS_NOATIME|MS_NODEV))

				       MS_NOATIME))

	{

	{

		die("MS_RELATIME malfunctions\n");

		die("MS_RELATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_STRICTATIME,

				       MS_NOATIME|MS_NODEV))

				       MS_NOATIME))

	{

	{

		die("MS_STRICTATIME malfunctions\n");

		die("MS_STRICTATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_NOATIME,

				       MS_STRICTATIME|MS_NODEV))

				       MS_STRICTATIME))

	{

	{

		die("MS_RELATIME malfunctions\n");

		die("MS_NOATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME,

				       MS_NOATIME|MS_NODEV))

				       MS_NOATIME))

	{

	{

		die("MS_RELATIME malfunctions\n");

		die("MS_RELATIME|MS_NODIRATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME,

				       MS_NOATIME|MS_NODEV))

				       MS_NOATIME))

	{

	{

		die("MS_RELATIME malfunctions\n");

		die("MS_STRICTATIME|MS_NODIRATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME|MS_NODEV,

	if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME,

				       MS_STRICTATIME|MS_NODEV))

				       MS_STRICTATIME))

	{

	{

		die("MS_RELATIME malfunctions\n");

		die("MS_NOATIME|MS_DIRATIME malfunctions\n");

	}

	}

	if (!test_unpriv_remount(MS_STRICTATIME|MS_NODEV, MS_NODEV,

	if (!test_unpriv_remount("ramfs", NULL, MS_STRICTATIME, 0, MS_NOATIME))

				 MS_NOATIME|MS_NODEV))

	{

	{

		die("Default atime malfunctions\n");

		die("Default atime malfunctions\n");

	}

	}

	if (!test_priv_mount_unpriv_remount()) {

		die("Mount flags unexpectedly changed after remount\n");

	}

	return EXIT_SUCCESS;

	return EXIT_SUCCESS;

}
 
}