Commit 2bfbcccd authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: record either old name new name or both for FAN_RENAME 

We do not want to report the dirfid+name of a directory whose
inode/sb are not watched, because watcher may not have permissions
to see the directory content.

Use an internal iter_info to indicate to fanotify_alloc_event()
which marks of this group are watching FAN_RENAME, so it can decide
if we need to record only the old parent+name, new parent+name or both.

Link: https://lore.kernel.org/r/20211129201537.1932819-10-amir73il@gmail.com


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
[JK: Modified code to pass around only mask of mark types matching
generated event]
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 3982534b

fs/notify/fanotify/fanotify.c

+44 −15
Original line number Diff line number Diff line
@@ -284,8 +284,9 @@ static int fanotify_get_response(struct fsnotify_group *group, 
 */

static u32 fanotify_group_event_mask(struct fsnotify_group *group,

				     struct fsnotify_iter_info *iter_info,

				     u32 event_mask, const void *data,

				     int data_type, struct inode *dir)

				     u32 *match_mask, u32 event_mask,

				     const void *data, int data_type,

				     struct inode *dir)

{

	__u32 marks_mask = 0, marks_ignored_mask = 0;

	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
@@ -335,6 +336,9 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group, 
			continue;



		marks_mask |= mark->mask;



		/* Record the mark types of this group that matched the event */

		*match_mask |= 1U << type;

	}



	test_mask = event_mask & marks_mask & ~marks_ignored_mask;
@@ -701,11 +705,11 @@ static struct fanotify_event *fanotify_alloc_error_event( 
	return &fee->fae;

}



static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,

						   u32 mask, const void *data,

						   int data_type, struct inode *dir,

						   const struct qstr *file_name,

						   __kernel_fsid_t *fsid)

static struct fanotify_event *fanotify_alloc_event(

				struct fsnotify_group *group,

				u32 mask, const void *data, int data_type,

				struct inode *dir, const struct qstr *file_name,

				__kernel_fsid_t *fsid, u32 match_mask)

{

	struct fanotify_event *event = NULL;

	gfp_t gfp = GFP_KERNEL_ACCOUNT;
@@ -753,14 +757,37 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, 
		}



		/*

		 * In the special case of FAN_RENAME event, we record both

		 * old and new parent+name.

		 * In the special case of FAN_RENAME event, use the match_mask

		 * to determine if we need to report only the old parent+name,

		 * only the new parent+name or both.

		 * 'dirid' and 'file_name' are the old parent+name and

		 * 'moved' has the new parent+name.

		 */

		if (mask & FAN_RENAME)

		if (mask & FAN_RENAME) {

			bool report_old, report_new;



			if (WARN_ON_ONCE(!match_mask))

				return NULL;



			/* Report both old and new parent+name if sb watching */

			report_old = report_new =

				match_mask & (1U << FSNOTIFY_ITER_TYPE_SB);

			report_old |=

				match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE);

			report_new |=

				match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE2);



			if (!report_old) {

				/* Do not report old parent+name */

				dirid = NULL;

				file_name = NULL;

			}

			if (report_new) {

				/* Report new parent+name */

				moved = fsnotify_data_dentry(data, data_type);

			}

		}

	}



	/*

	 * For queues with unlimited length lost events are not expected and
@@ -872,6 +899,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, 
	struct fanotify_event *event;

	struct fsnotify_event *fsn_event;

	__kernel_fsid_t fsid = {};

	u32 match_mask = 0;



	BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);

	BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
@@ -897,12 +925,13 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, 


	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);



	mask = fanotify_group_event_mask(group, iter_info, mask, data,

					 data_type, dir);

	mask = fanotify_group_event_mask(group, iter_info, &match_mask,

					 mask, data, data_type, dir);

	if (!mask)

		return 0;



	pr_debug("%s: group=%p mask=%x\n", __func__, group, mask);

	pr_debug("%s: group=%p mask=%x report_mask=%x\n", __func__,

		 group, mask, match_mask);



	if (fanotify_is_perm_event(mask)) {

		/*
@@ -921,7 +950,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, 
	}



	event = fanotify_alloc_event(group, mask, data, data_type, dir,

				     file_name, &fsid);

				     file_name, &fsid, match_mask);

	ret = -ENOMEM;

	if (unlikely(!event)) {

		/*