This adds make install support to selftests. The basic usage is:

$ cd tools/testing/selftests
$ make install

That installs into tools/testing/selftests/install, which can then be
copied where ever necessary.

The install destination is also configurable using eg:

$ INSTALL_PATH=/mnt/selftests make install

The implementation uses two targets in the child makefiles. The first
"install" is expected to install all files into $(INSTALL_PATH).

The second, "emit_tests", is expected to emit the test instructions (ie.
bash script) on stdout. Separating this from install means the child
makefiles need no knowledge of the location of the test script.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

This adds a Make include file which most selftests can then include to
get the run_tests logic.

On its own this has the advantage of some reduction in repetition, and
also means the pass/fail message is defined in fewer places.

However the key advantage is it will allow us to implement install very
simply in a subsequent patch.

The default implementation just executes each program in $(TEST_PROGS).

We use a variable to hold the default implementation of $(RUN_TESTS)
because that gives us a clean way to override it if necessary, ie. using
override. The mount, memory-hotplug and mqueue tests use that to provide
a different implementation.

Tests are not run via /bin/bash, so if they are scripts they must be
executable, we add a+x to several.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

A security fix in caused the way the unprivileged remount tests were
using user namespaces to break.  Tweak the way user namespaces are
being used so the test works again.

Cc: stable@vger.kernel.org
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

- 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: NEric W. Biederman <ebiederm@xmission.com>

Kenton Varda <kenton@sandstorm.io> discovered that by remounting a
read-only bind mount read-only in a user namespace the
MNT_LOCK_READONLY bit would be cleared, allowing an unprivileged user
to the remount a read-only mount read-write.

Upon review of the code in remount it was discovered that the code allowed
nosuid, noexec, and nodev to be cleared.  It was also discovered that
the code was allowing the per mount atime flags to be changed.

The first naive patch to fix these issues contained the flaw that using
default atime settings when remounting a filesystem could be disallowed.

To avoid this problems in the future add tests to ensure unprivileged
remounts are succeeding and failing at the appropriate times.

Cc: stable@vger.kernel.org
Acked-by: NSerge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>