selftests/landlock: Add wrappers.h

Extract syscall wrappers to make them usable by standalone binaries (see
next commit).

Cc: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20250108154338.1129069-22-mic@digikod.net
[mic: Fix comments]
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Author: l0kod

tools/testing/selftests/landlock/common.h

@@ -9,17 +9,15 @@
 
 #include <arpa/inet.h>
 #include <errno.h>
-#include <linux/landlock.h>
 #include <linux/securebits.h>
 #include <sys/capability.h>
 #include <sys/socket.h>
-#include <sys/syscall.h>
-#include <sys/types.h>
 #include <sys/un.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
 #include "../kselftest_harness.h"
+#include "wrappers.h"
 
 #define TMP_DIR "tmp"
 
@@ -30,34 +28,6 @@
 /* TEST_F_FORK() should not be used for new tests. */
 #define TEST_F_FORK(fixture_name, test_name) TEST_F(fixture_name, test_name)
 
-#ifndef landlock_create_ruleset
-static inline int
-landlock_create_ruleset(const struct landlock_ruleset_attr *const attr,
-			const size_t size, const __u32 flags)
-{
-	return syscall(__NR_landlock_create_ruleset, attr, size, flags);
-}
-#endif
-
-#ifndef landlock_add_rule
-static inline int landlock_add_rule(const int ruleset_fd,
-				    const enum landlock_rule_type rule_type,
-				    const void *const rule_attr,
-				    const __u32 flags)
-{
-	return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr,
-		       flags);
-}
-#endif
-
-#ifndef landlock_restrict_self
-static inline int landlock_restrict_self(const int ruleset_fd,
-					 const __u32 flags)
-{
-	return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
-}
-#endif
-
 static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 {
 	cap_t cap_p;
@@ -250,11 +220,6 @@ struct service_fixture {
 	};
 };
 
-static pid_t __maybe_unused sys_gettid(void)
-{
-	return syscall(__NR_gettid);
-}
-
 static void __maybe_unused set_unix_address(struct service_fixture *const srv,
 					    const unsigned short index)
 {

tools/testing/selftests/landlock/wrappers.h

@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Syscall wrappers
+ *
+ * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2019-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
+ */
+
+#define _GNU_SOURCE
+#include <linux/landlock.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#ifndef landlock_create_ruleset
+static inline int
+landlock_create_ruleset(const struct landlock_ruleset_attr *const attr,
+			const size_t size, const __u32 flags)
+{
+	return syscall(__NR_landlock_create_ruleset, attr, size, flags);
+}
+#endif
+
+#ifndef landlock_add_rule
+static inline int landlock_add_rule(const int ruleset_fd,
+				    const enum landlock_rule_type rule_type,
+				    const void *const rule_attr,
+				    const __u32 flags)
+{
+	return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr,
+		       flags);
+}
+#endif
+
+#ifndef landlock_restrict_self
+static inline int landlock_restrict_self(const int ruleset_fd,
+					 const __u32 flags)
+{
+	return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
+}
+#endif
+
+static inline pid_t sys_gettid(void)
+{
+	return syscall(__NR_gettid);
+}