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

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.)

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>

[...]
 			_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

-- 
Kees Cook