selftests/landlock: Test handling of unknown scope

Add a new ruleset_with_unknown_scope test designed to validate the
behaviour of landlock_create_ruleset(2) when called with an unsupported
or unknown scope mask.

Signed-off-by: Tahera Fahimi <[e-mail]>
Link: https://lore.kernel.org/r/74b3[e-mail]
Signed-off-by: Mickaël Salaün <[e-mail]>

tools/testing/selftests/landlock/scoped_test.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock tests - Common scope restriction
+ *
+ * Copyright © 2024 Tahera Fahimi <[e-mail]>
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/landlock.h>
+#include <sys/prctl.h>
+
+#include "common.h"
+
+#define ACCESS_LAST LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET
+
+TEST(ruleset_with_unknown_scope)
+{
+	__u64 scoped_mask;
+
+	for (scoped_mask = 1ULL << 63; scoped_mask != ACCESS_LAST;
+	     scoped_mask >>= 1) {
+		struct landlock_ruleset_attr ruleset_attr = {
+			.scoped = scoped_mask,
+		};
+
+		ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr,
+						      sizeof(ruleset_attr), 0));
+		ASSERT_EQ(EINVAL, errno);
+	}
+}
+
+TEST_HARNESS_MAIN