landlock: Change landlock_add_rule(2) argument check ordering

This makes more sense to first check the ruleset FD and then the rule
attribute.  It will be useful to factor out code for other rule types.

Add inval_add_rule_arguments tests, extension of empty_path_beneath_attr
tests, to also check error ordering for landlock_add_rule(2).

Link: https://lore.kernel.org/r/20220506160820.524344-9-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>

1 files changed, 32 insertions, 2 deletions

diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index be9b937256ac..18b779471dcb 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -121,20 +121,50 @@ TEST(inval_create_ruleset_flags)
 	ASSERT_EQ(EINVAL, errno);
 }
 
-TEST(empty_path_beneath_attr)
+/* Tests ordering of syscall argument checks. */
+TEST(add_rule_checks_ordering)
 {
 	const struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = LANDLOCK_ACCESS_FS_EXECUTE,
 	};
+	struct landlock_path_beneath_attr path_beneath_attr = {
+		.allowed_access = LANDLOCK_ACCESS_FS_EXECUTE,
+		.parent_fd = -1,
+	};
 	const int ruleset_fd =
 		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
 
 	ASSERT_LE(0, ruleset_fd);
 
-	/* Similar to struct landlock_path_beneath_attr.parent_fd = 0 */
+	/* Checks invalid flags. */
+	ASSERT_EQ(-1, landlock_add_rule(-1, 0, NULL, 1));
+	ASSERT_EQ(EINVAL, errno);
+
+	/* Checks invalid ruleset FD. */
+	ASSERT_EQ(-1, landlock_add_rule(-1, 0, NULL, 0));
+	ASSERT_EQ(EBADF, errno);
+
+	/* Checks invalid rule type. */
+	ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, 0, NULL, 0));
+	ASSERT_EQ(EINVAL, errno);
+
+	/* Checks invalid rule attr. */
 	ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
 					NULL, 0));
 	ASSERT_EQ(EFAULT, errno);
+
+	/* Checks invalid path_beneath.parent_fd. */
+	ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+					&path_beneath_attr, 0));
+	ASSERT_EQ(EBADF, errno);
+
+	/* Checks valid call. */
+	path_beneath_attr.parent_fd =
+		open("/tmp", O_PATH | O_NOFOLLOW | O_DIRECTORY | O_CLOEXEC);
+	ASSERT_LE(0, path_beneath_attr.parent_fd);
+	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+				       &path_beneath_attr, 0));
+	ASSERT_EQ(0, close(path_beneath_attr.parent_fd));
 	ASSERT_EQ(0, close(ruleset_fd));
 }