On Mon, Feb 26, 2024 at 11:04:12AM -0800, Kees Cook wrote:

On Mon, Feb 26, 2024 at 05:23:35PM +0100, Mickaël Salaün wrote:

quoted

Remplace Landlock-specific TEST_F_FORK() with an improved TEST_F() which
brings four related changes:

Run TEST_F()'s tests in a grandchild process to make it possible to
drop privileges and delegate teardown to the parent.

Compared to TEST_F_FORK(), simplify handling of the test grandchild
process thanks to vfork(2), and makes it generic (e.g. no explicit
conversion between exit code and _metadata).

Compared to TEST_F_FORK(), run teardown even when tests failed with an
assert thanks to commit 63e6b2a42342 ("selftests/harness: Run TEARDOWN
for ASSERT failures").

Simplify the test harness code by removing the no_print and step fields
which are not used.  I added this feature just after I made
kselftest_harness.h more broadly available but this step counter
remained even though it wasn't needed after all. See commit 369130b63178
("selftests: Enhance kselftest_harness.h to print which assert failed").

I'm personally fine dropping the step counter. (I do wonder if that
removal should be split from the grandchild launching.)

I thought about that but it was not worth it to add more lines to
review.

quoted

Replace spaces with tabs in one line of __TEST_F_IMPL().

Cc: Günther Noack <gnoack@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Kees Cook <redacted>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>

One typo below, but otherwise seems good to me:

Reviewed-by: Kees Cook <redacted>

quoted

[...]
 			_metadata->setup_completed = true; \
-			fixture_name##_##test_name(_metadata, &self, variant->data); \
+			/* Use the same _metadata. */ \
+			child = vfork(); \
+			if (child == 0) { \
+				fixture_name##_##test_name(_metadata, &self, variant->data); \
+				_exit(0); \
+			} \
+			if (child < 0) { \
+				ksft_print_msg("ERROR SPAWNING TEST GANDCHILD\n"); \

typo: GAND -> GRAND

Good catch!

Jakub, please fix this with the next combined+rebased series. Thanks!

-- 
Kees Cook