Commit 691d9763 authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: report parent fid + child fid 

Add support for FAN_REPORT_FID | FAN_REPORT_DIR_FID.
Internally, it is implemented as a private case of reporting both
parent and child fids and name, the parent and child fids are recorded
in a variable length fanotify_name_event, but there is no name.

It should be noted that directory modification events are recorded
in fixed size fanotify_fid_event when not reporting name, just like
with group flags FAN_REPORT_FID.

Link: https://lore.kernel.org/r/20200716084230.30611-23-amir73il@gmail.com


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 7e8283af

fs/notify/fanotify/fanotify.c

+11 −5
Original line number Diff line number Diff line
@@ -535,7 +535,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, 
		/*

		 * With both flags FAN_REPORT_DIR_FID and FAN_REPORT_FID, we

		 * report the child fid for events reported on a non-dir child

		 * in addition to reporting the parent fid and child name.

		 * in addition to reporting the parent fid and maybe child name.

		 */

		if ((fid_mode & FAN_REPORT_FID) &&

		    id != dirid && !(mask & FAN_ONDIR))
@@ -552,12 +552,18 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, 
		 *

		 * For event on non-directory that is reported to parent, we

		 * record the fid of the parent and the name of the child.

		 *

		 * Even if not reporting name, we need a variable length

		 * fanotify_name_event if reporting both parent and child fids.

		 */

		if ((fid_mode & FAN_REPORT_NAME) &&

		    ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||

		     !(mask & FAN_ONDIR)))

		if (!(fid_mode & FAN_REPORT_NAME)) {

			name_event = !!child;

			file_name = NULL;

		} else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||

			   !(mask & FAN_ONDIR)) {

			name_event = true;

		}

	}



	/*

	 * For queues with unlimited length lost events are not expected and
@@ -575,7 +581,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, 


	if (fanotify_is_perm_event(mask)) {

		event = fanotify_alloc_perm_event(path, gfp);

	} else if (name_event && file_name) {

	} else if (name_event && (file_name || child)) {

		event = fanotify_alloc_name_event(id, fsid, file_name, child,

						  gfp);

	} else if (fid_mode) {

fs/notify/fanotify/fanotify_user.c

+4 −11
Original line number Diff line number Diff line
@@ -371,7 +371,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, 


	/* Event info records order is: dir fid + name, child fid */

	if (fanotify_event_dir_fh_len(event)) {

		info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;

		info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :

					     FAN_EVENT_INFO_TYPE_DFID;

		ret = copy_info_to_user(fanotify_event_fsid(event),

					fanotify_info_dir_fh(info),

					info_type, fanotify_info_name(info),
@@ -957,18 +958,10 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 


	/*

	 * Child name is reported with parent fid so requires dir fid.

	 * If reporting child name, we can report both child fid and dir fid.

	 * We can report both child fid and dir fid with or without name.

	 */

	switch (fid_mode) {

	case 0:

	case FAN_REPORT_FID:

	case FAN_REPORT_DIR_FID:

	case FAN_REPORT_DFID_NAME:

	case FAN_REPORT_DFID_NAME | FAN_REPORT_FID:

		break;

	default:

	if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID))

		return -EINVAL;

	}



	user = get_current_user();

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

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