Commit 83b535d2 authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: support events with data type FSNOTIFY_EVENT_INODE 



When event data type is FSNOTIFY_EVENT_INODE, we don't have a refernece
to the mount, so we will not be able to open a file descriptor when user
reads the event. However, if the listener has enabled reporting file
identifier with the FAN_REPORT_FID init flag, we allow reporting those
events and we use an identifier inode to encode fid.

The inode to use as identifier when reporting fid depends on the event.
For dirent modification events, we report the modified directory inode
and we report the "victim" inode otherwise.
For example:
FS_ATTRIB reports the child inode even if reported on a watched parent.
FS_CREATE reports the modified dir inode and not the created inode.

[JK: Fixup condition in fanotify_group_event_mask()]

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 0321e03c

fs/notify/fanotify/fanotify.c

+43 −20
Original line number Diff line number Diff line
@@ -106,7 +106,8 @@ static int fanotify_get_response(struct fsnotify_group *group, 
 * been included within the event mask, but have not been explicitly

 * requested by the user, will not be present in the returned mask.

 */

static u32 fanotify_group_event_mask(struct fsnotify_iter_info *iter_info,

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)

{
@@ -118,14 +119,14 @@ static u32 fanotify_group_event_mask(struct fsnotify_iter_info *iter_info, 
	pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",

		 __func__, iter_info->report_mask, event_mask, data, data_type);



	/* If we don't have enough info to send an event to userspace say no */

	if (!FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {

		/* Do we have path to open a file descriptor? */

		if (data_type != FSNOTIFY_EVENT_PATH)

			return 0;



	/* Sorry, fanotify only gives a damn about files and dirs */

	if (!d_is_reg(path->dentry) &&

	    !d_can_lookup(path->dentry))

		/* Path type events are only relevant for files and dirs */

		if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))

			return 0;

	}



	fsnotify_foreach_obj_type(type) {

		if (!fsnotify_iter_should_report_type(iter_info, type))
@@ -198,13 +199,34 @@ out_err: 
	return FILEID_INVALID;

}



/*

 * The inode to use as identifier when reporting fid depends on the event.

 * Report the modified directory inode on dirent modification events.

 * Report the "victim" inode otherwise.

 * For example:

 * FS_ATTRIB reports the child inode even if reported on a watched parent.

 * FS_CREATE reports the modified dir inode and not the created inode.

 */

static struct inode *fanotify_fid_inode(struct inode *to_tell, u32 event_mask,

					const void *data, int data_type)

{

	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)

		return to_tell;

	else if (data_type == FSNOTIFY_EVENT_INODE)

		return (struct inode *)data;

	else if (data_type == FSNOTIFY_EVENT_PATH)

		return d_inode(((struct path *)data)->dentry);

	return NULL;

}



struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,

					    struct inode *inode, u32 mask,

					    const struct path *path,

					    const void *data, int data_type,

					    __kernel_fsid_t *fsid)

{

	struct fanotify_event *event = NULL;

	gfp_t gfp = GFP_KERNEL_ACCOUNT;

	struct inode *id = fanotify_fid_inode(inode, mask, data, data_type);



	/*

	 * For queues with unlimited length lost events are not expected and
@@ -238,13 +260,12 @@ init: __maybe_unused 
	else

		event->pid = get_pid(task_tgid(current));

	event->fh_len = 0;

	if (path && FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {

	if (id && FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {

		/* Report the event without a file identifier on encode error */

		event->fh_type = fanotify_encode_fid(event,

					d_inode(path->dentry), gfp, fsid);

	} else if (path) {

		event->fh_type = fanotify_encode_fid(event, id, gfp, fsid);

	} else if (data_type == FSNOTIFY_EVENT_PATH) {

		event->fh_type = FILEID_ROOT;

		event->path = *path;

		event->path = *((struct path *)data);

		path_get(&event->path);

	} else {

		event->fh_type = FILEID_INVALID;
@@ -305,7 +326,8 @@ static int fanotify_handle_event(struct fsnotify_group *group, 


	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 12);



	mask = fanotify_group_event_mask(iter_info, mask, data, data_type);

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

					 data_type);

	if (!mask)

		return 0;
@@ -324,7 +346,8 @@ static int fanotify_handle_event(struct fsnotify_group *group, 
	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID))

		fsid = fanotify_get_fsid(iter_info);



	event = fanotify_alloc_event(group, inode, mask, data, &fsid);

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

				     &fsid);

	ret = -ENOMEM;

	if (unlikely(!event)) {

		/*

fs/notify/fanotify/fanotify.h

+1 −1
Original line number Diff line number Diff line
@@ -132,5 +132,5 @@ static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse) 


struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,

					    struct inode *inode, u32 mask,

					    const struct path *path,

					    const void *data, int data_type,

					    __kernel_fsid_t *fsid);

fs/notify/fanotify/fanotify_user.c

+2 −1
Original line number Diff line number Diff line
@@ -800,7 +800,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	atomic_inc(&user->fanotify_listeners);

	group->memcg = get_mem_cgroup_from_mm(current->mm);



	oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL, NULL);

	oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL,

				      FSNOTIFY_EVENT_NONE, NULL);

	if (unlikely(!oevent)) {

		fd = -ENOMEM;

		goto out_destroy_group;

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