lsm: split the notifier code out into lsm_notifier.c

In an effort to decompose security/security.c somewhat to make it less
twisted and unwieldy, pull out the LSM notifier code into a new file
as it is fairly well self-contained.

No code changes.

Reviewed-by: Kees Cook <[e-mail]>
Reviewed-by: John Johansen <[e-mail]>
Reviewed-by: Casey Schaufler <[e-mail]>
Reviewed-by: Mimi Zohar <[e-mail]>
Signed-off-by: Paul Moore <[e-mail]>

security/Makefile

···
 obj-$(CONFIG_MMU)			+= min_addr.o
 
 # Object file lists
-obj-$(CONFIG_SECURITY)			+= security.o
+obj-$(CONFIG_SECURITY)			+= security.o lsm_notifier.o
 obj-$(CONFIG_SECURITYFS)		+= inode.o
 obj-$(CONFIG_SECURITY_SELINUX)		+= selinux/
 obj-$(CONFIG_SECURITY_SMACK)		+= smack/

security/lsm_notifier.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LSM notifier functions
+ *
+ */
+
+#include <linux/notifier.h>
+#include <linux/security.h>
+
+static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);
+
+int call_blocking_lsm_notifier(enum lsm_event event, void *data)
+{
+	return blocking_notifier_call_chain(&blocking_lsm_notifier_chain,
+					    event, data);
+}
+EXPORT_SYMBOL(call_blocking_lsm_notifier);
+
+int register_blocking_lsm_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&blocking_lsm_notifier_chain,
+						nb);
+}
+EXPORT_SYMBOL(register_blocking_lsm_notifier);
+
+int unregister_blocking_lsm_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&blocking_lsm_notifier_chain,
+						  nb);
+}
+EXPORT_SYMBOL(unregister_blocking_lsm_notifier);

security/security.c

···
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);
-
 static struct kmem_cache *lsm_file_cache;
 static struct kmem_cache *lsm_inode_cache;
 
···
 			panic("%s - Cannot get early memory.\n", __func__);
 	}
 }
-
-int call_blocking_lsm_notifier(enum lsm_event event, void *data)
-{
-	return blocking_notifier_call_chain(&blocking_lsm_notifier_chain,
-					    event, data);
-}
-EXPORT_SYMBOL(call_blocking_lsm_notifier);
-
-int register_blocking_lsm_notifier(struct notifier_block *nb)
-{
-	return blocking_notifier_chain_register(&blocking_lsm_notifier_chain,
-						nb);
-}
-EXPORT_SYMBOL(register_blocking_lsm_notifier);
-
-int unregister_blocking_lsm_notifier(struct notifier_block *nb)
-{
-	return blocking_notifier_chain_unregister(&blocking_lsm_notifier_chain,
-						  nb);
-}
-EXPORT_SYMBOL(unregister_blocking_lsm_notifier);
 
 /**
  * lsm_blob_alloc - allocate a composite blob