fsnotify, lsm: Decouple fsnotify from lsm

Currently, fsnotify_open_perm() is called from security_file_open().
This is a a bit unexpected and creates otherwise unnecessary dependency
of CONFIG_FANOTIFY_ACCESS_PERMISSIONS on CONFIG_SECURITY. Fix this by
calling fsnotify_open_perm() directly.

Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20241013002248.3984442-1-song@kernel.org

Author: liu-song-6

fs/notify/fanotify/Kconfig

@@ -15,7 +15,6 @@ config FANOTIFY
 config FANOTIFY_ACCESS_PERMISSIONS
 	bool "fanotify permissions checking"
 	depends on FANOTIFY
-	depends on SECURITY
 	default n
 	help
 	   Say Y here is you want fanotify listeners to be able to make permissions

fs/open.c

@@ -946,6 +946,10 @@ static int do_dentry_open(struct file *f,
 	if (error)
 		goto cleanup_all;
 
+	error = fsnotify_open_perm(f);
+	if (error)
+		goto cleanup_all;
+
 	error = break_lease(file_inode(f), f->f_flags);
 	if (error)
 		goto cleanup_all;

security/security.c

@@ -19,7 +19,6 @@
 #include <linux/kernel.h>
 #include <linux/kernel_read_file.h>
 #include <linux/lsm_hooks.h>
-#include <linux/fsnotify.h>
 #include <linux/mman.h>
 #include <linux/mount.h>
 #include <linux/personality.h>
@@ -3104,13 +3103,7 @@ int security_file_receive(struct file *file)
  */
 int security_file_open(struct file *file)
 {
-	int ret;
-
-	ret = call_int_hook(file_open, file);
-	if (ret)
-		return ret;
-
-	return fsnotify_open_perm(file);
+	return call_int_hook(file_open, file);
 }
 
 /**