selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags

Add the base_test's restrict_self_fd_flags tests to align with previous
restrict_self_fd tests but with the new
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF flag.

Add the restrict_self_flags tests to check that
LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON, and
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF are valid but not the next
bit. Some checks are similar to restrict_self_checks_ordering's ones.

Cc: Günther Noack <[e-mail]>
Cc: Paul Moore <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mickaël Salaün <[e-mail]>

tools/testing/selftests/landlock/base_test.c

···
 	EXPECT_EQ(EBADFD, errno);
 }
 
+TEST(restrict_self_fd_flags)
+{
+	int fd;
+
+	fd = open("/dev/null", O_RDONLY | O_CLOEXEC);
+	ASSERT_LE(0, fd);
+
+	/*
+	 * LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF accepts -1 but not any file
+	 * descriptor.
+	 */
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      fd, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADFD, errno);
+}
+
+TEST(restrict_self_flags)
+{
+	const __u32 last_flag = LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF;
+
+	/* Tests invalid flag combinations. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, last_flag << 1));
+	EXPECT_EQ(EINVAL, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, -1));
+	EXPECT_EQ(EINVAL, errno);
+
+	/* Tests valid flag combinations. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, 0));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -1, LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1,
+			  LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF |
+				  LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1,
+			  LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON |
+				  LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -1, LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1, LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF |
+				      LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON));
+	EXPECT_EQ(EBADF, errno);
+
+	/* Tests with an invalid ruleset_fd. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -2, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(0, landlock_restrict_self(
+			     -1, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+}
+
 TEST(ruleset_fd_io)
 {
 	struct landlock_ruleset_attr ruleset_attr = {