fanotify: add BUILD_BUG_ON() to count the bits of fanotify constants

Also define the FANOTIFY_EVENT_FLAGS consisting of the extra flags
FAN_ONDIR and FAN_ON_CHILD.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fanotify/fanotify.c

@@ -205,6 +205,8 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 	BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
 	BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
 
+	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 10);
+
 	if (!fanotify_should_send_event(iter_info, mask, data, data_type))
 		return 0;
 

fs/notify/fanotify/fanotify_user.c

@@ -803,7 +803,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	struct fsnotify_group *group;
 	struct fd f;
 	struct path path;
-	u32 valid_mask = FANOTIFY_EVENTS | FAN_EVENT_ON_CHILD | FAN_ONDIR;
+	u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
 	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
 	int ret;
 
@@ -944,6 +944,9 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
  */
 static int __init fanotify_user_setup(void)
 {
+	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 6);
+	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
+
 	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
 					 SLAB_PANIC|SLAB_ACCOUNT);
 	fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);

include/linux/fanotify.h

@@ -41,11 +41,17 @@
 /* Events that require a permission response from user */
 #define FANOTIFY_PERM_EVENTS	(FAN_OPEN_PERM | FAN_ACCESS_PERM)
 
+/* Extra flags that may be reported with event or control handling of events */
+#define FANOTIFY_EVENT_FLAGS	(FAN_EVENT_ON_CHILD | FAN_ONDIR)
+
 /* Events that may be reported to user */
 #define FANOTIFY_OUTGOING_EVENTS	(FANOTIFY_EVENTS | \
 					 FANOTIFY_PERM_EVENTS | \
 					 FAN_Q_OVERFLOW)
 
+#define ALL_FANOTIFY_EVENT_BITS		(FANOTIFY_OUTGOING_EVENTS | \
+					 FANOTIFY_EVENT_FLAGS)
+
 /* Do not use these old uapi constants internally */
 #undef FAN_ALL_CLASS_BITS
 #undef FAN_ALL_INIT_FLAGS