Commit 4afeff85 authored by Eric Paris's avatar Eric Paris
Browse files

fanotify: limit number of listeners per user 



fanotify currently has no limit on the number of listeners a given user can
have open.  This patch limits the total number of listeners per user to
128.  This is the same as the inotify default limit.

Signed-off-by: default avatarEric Paris <eparis@redhat.com>
parent ac7e22dc

fs/notify/fanotify/fanotify.c

+10 −1
Original line number Diff line number Diff line
@@ -200,10 +200,19 @@ static bool fanotify_should_send_event(struct fsnotify_group *group, 
	return false;

}



static void fanotify_free_group_priv(struct fsnotify_group *group)

{

	struct user_struct *user;



	user = group->fanotify_data.user;

	atomic_dec(&user->fanotify_listeners);

	free_uid(user);

}



const struct fsnotify_ops fanotify_fsnotify_ops = {

	.handle_event = fanotify_handle_event,

	.should_send_event = fanotify_should_send_event,

	.free_group_priv = NULL,

	.free_group_priv = fanotify_free_group_priv,

	.free_event_priv = NULL,

	.freeing_mark = NULL,

};

fs/notify/fanotify/fanotify_user.c

+11 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 


#define FANOTIFY_DEFAULT_MAX_EVENTS	16384

#define FANOTIFY_DEFAULT_MAX_MARKS	8192

#define FANOTIFY_DEFAULT_MAX_LISTENERS	128



extern const struct fsnotify_ops fanotify_fsnotify_ops;
@@ -656,6 +657,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
{

	struct fsnotify_group *group;

	int f_flags, fd;

	struct user_struct *user;



	pr_debug("%s: flags=%d event_f_flags=%d\n",

		__func__, flags, event_f_flags);
@@ -666,6 +668,12 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	if (flags & ~FAN_ALL_INIT_FLAGS)

		return -EINVAL;



	user = get_current_user();

	if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {

		free_uid(user);

		return -EMFILE;

	}



	f_flags = O_RDWR | FMODE_NONOTIFY;

	if (flags & FAN_CLOEXEC)

		f_flags |= O_CLOEXEC;
@@ -677,6 +685,9 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	if (IS_ERR(group))

		return PTR_ERR(group);



	group->fanotify_data.user = user;

	atomic_inc(&user->fanotify_listeners);



	group->fanotify_data.f_flags = event_f_flags;

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS

	mutex_init(&group->fanotify_data.access_mutex);

include/linux/fsnotify_backend.h

+1 −0
Original line number Diff line number Diff line
@@ -170,6 +170,7 @@ struct fsnotify_group { 
#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */

			int f_flags;

			unsigned int max_marks;

			struct user_struct *user;

		} fanotify_data;

#endif /* CONFIG_FANOTIFY */

	};

include/linux/sched.h

+3 −0
Original line number Diff line number Diff line
@@ -672,6 +672,9 @@ struct user_struct { 
	atomic_t inotify_watches; /* How many inotify watches does this user have? */

	atomic_t inotify_devs;	/* How many inotify devs does this user have opened? */

#endif

#ifdef CONFIG_FANOTIFY

	atomic_t fanotify_listeners;

#endif

#ifdef CONFIG_EPOLL

	atomic_t epoll_watches;	/* The number of file descriptors currently watched */

#endif