Commit 83b7a598 authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: add basic support for FAN_REPORT_DIR_FID 

For now, the flag is mutually exclusive with FAN_REPORT_FID.
Events include a single info record of type FAN_EVENT_INFO_TYPE_DFID
with a directory file handle.

For now, events are only reported for:
- Directory modification events
- Events on children of a watching directory
- Events on directory objects

Soon, we will add support for reporting the parent directory fid
for events on non-directories with filesystem/mount mark and
support for reporting both parent directory fid and child fid.

Link: https://lore.kernel.org/r/20200716084230.30611-19-amir73il@gmail.com


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 79cb299c

fs/notify/fanotify/fanotify.c

+32 −2
Original line number Diff line number Diff line
@@ -223,7 +223,7 @@ 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)

				     int data_type, struct inode *dir)

{

	__u32 marks_mask = 0, marks_ignored_mask = 0;

	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
@@ -243,6 +243,10 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group, 
		/* Path type events are only relevant for files and dirs */

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

			return 0;

	} else if (!(fid_mode & FAN_REPORT_FID)) {

		/* Do we have a directory inode to report? */

		if (!dir && !(event_mask & FS_ISDIR))

			return 0;

	}



	fsnotify_foreach_obj_type(type) {
@@ -396,6 +400,28 @@ static struct inode *fanotify_fid_inode(u32 event_mask, const void *data, 
	return fsnotify_data_inode(data, data_type);

}



/*

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

 * Report the modified directory inode on dirent modification events.

 * Report the "victim" inode if "victim" is a directory.

 * Report the parent inode if "victim" is not a directory and event is

 * reported to parent.

 * Otherwise, do not report dir fid.

 */

static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,

					 int data_type, struct inode *dir)

{

	struct inode *inode = fsnotify_data_inode(data, data_type);



	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)

		return dir;



	if (S_ISDIR(inode->i_mode))

		return inode;



	return dir;

}



static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,

							gfp_t gfp)

{
@@ -491,10 +517,14 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, 
	struct fanotify_event *event = NULL;

	gfp_t gfp = GFP_KERNEL_ACCOUNT;

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

	struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);

	const struct path *path = fsnotify_data_path(data, data_type);

	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);

	bool name_event = false;



	if ((fid_mode & FAN_REPORT_DIR_FID) && dirid)

		id = dirid;



	/*

	 * For queues with unlimited length lost events are not expected and

	 * can possibly have security implications. Avoid losing events when
@@ -605,7 +635,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, 
	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);



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

					 data_type);

					 data_type, dir);

	if (!mask)

		return 0;

fs/notify/fanotify/fanotify_user.c

+61 −10
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ static int process_access_response(struct fsnotify_group *group, 
}



static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,

			     const char *name, size_t name_len,

			     int info_type, const char *name, size_t name_len,

			     char __user *buf, size_t count)

{

	struct fanotify_event_info_fid info = { };
@@ -229,7 +229,7 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, 
	pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",

		 __func__, fh_len, name_len, info_len, count);



	if (!fh_len || (name && !name_len))

	if (!fh_len)

		return 0;



	if (WARN_ON_ONCE(len < sizeof(info) || len > count))
@@ -239,8 +239,21 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, 
	 * Copy event info fid header followed by variable sized file handle

	 * and optionally followed by variable sized filename.

	 */

	info.hdr.info_type = name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :

					FAN_EVENT_INFO_TYPE_FID;

	switch (info_type) {

	case FAN_EVENT_INFO_TYPE_FID:

	case FAN_EVENT_INFO_TYPE_DFID:

		if (WARN_ON_ONCE(name_len))

			return -EFAULT;

		break;

	case FAN_EVENT_INFO_TYPE_DFID_NAME:

		if (WARN_ON_ONCE(!name || !name_len))

			return -EFAULT;

		break;

	default:

		return -EFAULT;

	}



	info.hdr.info_type = info_type;

	info.hdr.len = len;

	info.fsid = *fsid;

	if (copy_to_user(buf, &info, sizeof(info)))
@@ -304,8 +317,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, 
	struct fanotify_event_metadata metadata;

	struct path *path = fanotify_event_path(event);

	struct fanotify_info *info = fanotify_event_info(event);

	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);

	struct file *f = NULL;

	int ret, fd = FAN_NOFD;

	int info_type = 0;



	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
@@ -346,9 +361,10 @@ 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;

		ret = copy_info_to_user(fanotify_event_fsid(event),

					fanotify_info_dir_fh(info),

					fanotify_info_name(info),

					info_type, fanotify_info_name(info),

					info->name_len, buf, count);

		if (ret < 0)

			return ret;
@@ -358,9 +374,33 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, 
	}



	if (fanotify_event_object_fh_len(event)) {

		if (fid_mode == FAN_REPORT_FID || info_type) {

			/*

			 * With only group flag FAN_REPORT_FID only type FID is

			 * reported. Second info record type is always FID.

			 */

			info_type = FAN_EVENT_INFO_TYPE_FID;

		} else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||

			   (event->mask & FAN_ONDIR)) {

			/*

			 * With group flag FAN_REPORT_DIR_FID, a single info

			 * record has type DFID for directory entry modification

			 * event and for event on a directory.

			 */

			info_type = FAN_EVENT_INFO_TYPE_DFID;

		} else {

			/*

			 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,

			 * a single info record has type FID for event on a

			 * non-directory, when there is no directory to report.

			 * For example, on FAN_DELETE_SELF event.

			 */

			info_type = FAN_EVENT_INFO_TYPE_FID;

		}



		ret = copy_info_to_user(fanotify_event_fsid(event),

					fanotify_event_object_fh(event),

					NULL, 0, buf, count);

					info_type, NULL, 0, buf, count);

		if (ret < 0)

			return ret;
@@ -861,6 +901,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	struct fsnotify_group *group;

	int f_flags, fd;

	struct user_struct *user;

	unsigned int fid_mode = flags & FANOTIFY_FID_BITS;

	unsigned int class = flags & FANOTIFY_CLASS_BITS;



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

		 __func__, flags, event_f_flags);
@@ -887,10 +929,19 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
		return -EINVAL;

	}



	if ((flags & FANOTIFY_FID_BITS) &&

	    (flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF)

	if (fid_mode && class != FAN_CLASS_NOTIF)

		return -EINVAL;



	/* Reporting either object fid or dir fid */

	switch (fid_mode) {

	case 0:

	case FAN_REPORT_FID:

	case FAN_REPORT_DIR_FID:

		break;

	default:

		return -EINVAL;

	}



	user = get_current_user();

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

		free_uid(user);
@@ -926,7 +977,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	group->fanotify_data.f_flags = event_f_flags;

	init_waitqueue_head(&group->fanotify_data.access_waitq);

	INIT_LIST_HEAD(&group->fanotify_data.access_list);

	switch (flags & FANOTIFY_CLASS_BITS) {

	switch (class) {

	case FAN_CLASS_NOTIF:

		group->priority = FS_PRIO_0;

		break;
@@ -1236,7 +1287,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark, 
 */

static int __init fanotify_user_setup(void)

{

	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8);

	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 9);

	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);



	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,

include/linux/fanotify.h

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ 
#define FANOTIFY_CLASS_BITS	(FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | \

				 FAN_CLASS_PRE_CONTENT)



#define FANOTIFY_FID_BITS	(FAN_REPORT_FID)

#define FANOTIFY_FID_BITS	(FAN_REPORT_FID | FAN_REPORT_DIR_FID)



#define FANOTIFY_INIT_FLAGS	(FANOTIFY_CLASS_BITS | FANOTIFY_FID_BITS | \

				 FAN_REPORT_TID | \

include/uapi/linux/fanotify.h

+7 −4
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
/* Flags to determine fanotify event format */

#define FAN_REPORT_TID		0x00000100	/* event->pid is thread id */

#define FAN_REPORT_FID		0x00000200	/* Report unique file id */

#define FAN_REPORT_DIR_FID	0x00000400	/* Report unique directory id */



/* Deprecated - do not use this in programs and do not add new flags here! */

#define FAN_ALL_INIT_FLAGS	(FAN_CLOEXEC | FAN_NONBLOCK | \
@@ -117,6 +118,7 @@ struct fanotify_event_metadata { 


#define FAN_EVENT_INFO_TYPE_FID		1

#define FAN_EVENT_INFO_TYPE_DFID_NAME	2

#define FAN_EVENT_INFO_TYPE_DFID	3



/* Variable length info record following event metadata */

struct fanotify_event_info_header {
@@ -126,10 +128,11 @@ struct fanotify_event_info_header { 
};



/*

 * Unique file identifier info record. This is used both for

 * FAN_EVENT_INFO_TYPE_FID records and for FAN_EVENT_INFO_TYPE_DFID_NAME

 * records. For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null

 * terminated name immediately after the file handle.

 * Unique file identifier info record.

 * This structure is used for records of types FAN_EVENT_INFO_TYPE_FID,

 * FAN_EVENT_INFO_TYPE_DFID and FAN_EVENT_INFO_TYPE_DFID_NAME.

 * For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null terminated

 * name immediately after the file handle.

 */

struct fanotify_event_info_fid {

	struct fanotify_event_info_header hdr;