linux-kernel - [PATCH v2 2/9] selftests/landlock: Fix FS tests when run on a private mount point

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Message-ID: <20240429130931.2394118-3-mic@digikod.net>
Date: Mon, 29 Apr 2024 15:09:24 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Christian Brauner <brauner@...nel.org>,
	Jakub Kicinski <kuba@...nel.org>,
	Kees Cook <keescook@...omium.org>,
	Mark Brown <broonie@...nel.org>,
	Shengyu Li <shengyu.li.evgeny@...il.com>,
	Shuah Khan <shuah@...nel.org>
Cc: Mickaël Salaün <mic@...ikod.net>,
	"David S . Miller" <davem@...emloft.net>,
	Günther Noack <gnoack@...gle.com>,
	Will Drewry <wad@...omium.org>,
	kernel test robot <oliver.sang@...el.com>,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Shuah Khan <skhan@...uxfoundation.org>
Subject: [PATCH v2 2/9] selftests/landlock: Fix FS tests when run on a private mount point

According to the test environment, the mount point of the test's working
directory may be shared or not, which changes the visibility of the
nested "tmp" mount point for the test's parent process calling
umount("tmp").

This was spotted while running tests in containers [1], where mount
points are private.

Cc: Günther Noack <gnoack@...gle.com>
Cc: Shuah Khan <skhan@...uxfoundation.org>
Link: https://github.com/landlock-lsm/landlock-test-tools/pull/4 [1]
Fixes: 41cca0542d7c ("selftests/harness: Fix TEST_F()'s vfork handling")
Reviewed-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Link: https://lore.kernel.org/r/20240429130931.2394118-3-mic@digikod.net
---

Changes since v1:
* Update commit description.
---
 tools/testing/selftests/landlock/fs_test.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 9a6036fbf289..46b9effd53e4 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -293,7 +293,15 @@ static void prepare_layout(struct __test_metadata *const _metadata)
 static void cleanup_layout(struct __test_metadata *const _metadata)
 {
 	set_cap(_metadata, CAP_SYS_ADMIN);
-	EXPECT_EQ(0, umount(TMP_DIR));
+	if (umount(TMP_DIR)) {
+		/*
+		 * According to the test environment, the mount point of the
+		 * current directory may be shared or not, which changes the
+		 * visibility of the nested TMP_DIR mount point for the test's
+		 * parent process doing this cleanup.
+		 */
+		ASSERT_EQ(EINVAL, errno);
+	}
 	clear_cap(_metadata, CAP_SYS_ADMIN);
 	EXPECT_EQ(0, remove_path(TMP_DIR));
 }
-- 
2.44.0