selftests/landlock: Test landlock_create_ruleset(2) argument check ordering

Add inval_create_ruleset_arguments, extension of
inval_create_ruleset_flags, to also check error ordering for
landlock_create_ruleset(2).

This is similar to the previous commit checking landlock_add_rule(2).

Test coverage for security/landlock is 94.4% of 504 lines accorging to
gcc/gcov-11.

Link: https://lore.kernel.org/r/20220506160820.524344-11-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>

tools/testing/selftests/landlock/base_test.c

@@ -97,14 +97,17 @@ TEST(abi_version)
 	ASSERT_EQ(EINVAL, errno);
 }
 
-TEST(inval_create_ruleset_flags)
+/* Tests ordering of syscall argument checks. */
+TEST(create_ruleset_checks_ordering)
 {
 	const int last_flag = LANDLOCK_CREATE_RULESET_VERSION;
 	const int invalid_flag = last_flag << 1;
+	int ruleset_fd;
 	const struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
 	};
 
+	/* Checks priority for invalid flags. */
 	ASSERT_EQ(-1, landlock_create_ruleset(NULL, 0, invalid_flag));
 	ASSERT_EQ(EINVAL, errno);
 
@@ -119,6 +122,22 @@ TEST(inval_create_ruleset_flags)
 		  landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr),
 					  invalid_flag));
 	ASSERT_EQ(EINVAL, errno);
+
+	/* Checks too big ruleset_attr size. */
+	ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, -1, 0));
+	ASSERT_EQ(E2BIG, errno);
+
+	/* Checks too small ruleset_attr size. */
+	ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, 0));
+	ASSERT_EQ(EINVAL, errno);
+	ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 1, 0));
+	ASSERT_EQ(EINVAL, errno);
+
+	/* Checks valid call. */
+	ruleset_fd =
+		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+	ASSERT_LE(0, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
 }
 
 /* Tests ordering of syscall argument checks. */