BACKPORT: Yama: Initialize as ordered LSM

This converts Yama from being a direct "minor" LSM into an ordered LSM.

Change-Id: Ie3d4cccfb950365b6a498114fa48ca06fcfe91fc
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>

include/linux/lsm_hooks.h

@@ -1552,10 +1552,5 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
 #endif /* CONFIG_SECURITY_WRITABLE_HOOKS */
 
 extern void __init capability_add_hooks(void);
-#ifdef CONFIG_SECURITY_YAMA
-extern void __init yama_add_hooks(void);
-#else
-static inline void __init yama_add_hooks(void) { }
-#endif
 
 #endif /* ! __LINUX_LSM_HOOKS_H */

security/Kconfig

@@ -244,7 +244,7 @@ source security/integrity/Kconfig
 
 config LSM
 	string "Ordered list of enabled LSMs"
-	default "loadpin,integrity,selinux,smack,tomoyo,apparmor,bpf"
+	default "yama,loadpin,integrity,selinux,smack,tomoyo,apparmor,bpf"
 	help
 	  A comma-separated list of LSMs, in initialization order.
 	  Any LSMs left off this list will be ignored. This can be

security/security.c

@@ -274,7 +274,6 @@ int __init security_init(void)
 	 * Load minor LSMs, with the capability module always first.
 	 */
 	capability_add_hooks();
-	yama_add_hooks();
 
 	/* Load LSMs in specified order. */
 	ordered_lsm_init();

security/yama/yama_lsm.c

@@ -479,9 +479,15 @@ static void __init yama_init_sysctl(void)
 static inline void yama_init_sysctl(void) { }
 #endif /* CONFIG_SYSCTL */
 
-void __init yama_add_hooks(void)
+static int __init yama_init(void)
 {
 	pr_info("Yama: becoming mindful.\n");
 	security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
 	yama_init_sysctl();
+	return 0;
 }
+
+DEFINE_LSM(yama) = {
+	.name = "yama",
+	.init = yama_init,
+};