fanotify: Store fanotify handles differently

Currently, struct fanotify_fid groups fsid and file handle and is
unioned together with struct path to save space. Also there is fh_type
and fh_len directly in struct fanotify_event to avoid padding overhead.
In the follwing patches, we will be adding more event types and this
packing makes code difficult to follow. So unpack everything and create
struct fanotify_fh which groups members logically related to file handle
to make code easier to follow. In the following patch we will pack
things again differently to make events smaller.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 20 insertions, 19 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index e48fc07d80ef..0b3b74fa3a27 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -53,11 +53,13 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
 
 static int fanotify_event_info_len(struct fanotify_event *event)
 {
-	if (!fanotify_event_has_fid(event))
+	int fh_len = fanotify_event_object_fh_len(event);
+
+	if (!fh_len)
 		return 0;
 
 	return roundup(sizeof(struct fanotify_event_info_fid) +
-		       sizeof(struct file_handle) + event->fh_len,
+		       sizeof(struct file_handle) + fh_len,
 		       FANOTIFY_EVENT_ALIGN);
 }
 
@@ -200,8 +202,9 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 {
 	struct fanotify_event_info_fid info = { };
 	struct file_handle handle = { };
-	unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh;
-	size_t fh_len = event->fh_len;
+	unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
+	struct fanotify_fh *fh = fanotify_event_object_fh(event);
+	size_t fh_len = fh->len;
 	size_t len = fanotify_event_info_len(event);
 
 	if (!len)
@@ -213,13 +216,13 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 	/* Copy event info fid header followed by vaiable sized file handle */
 	info.hdr.info_type = FAN_EVENT_INFO_TYPE_FID;
 	info.hdr.len = len;
-	info.fsid = event->fid.fsid;
+	info.fsid = *fanotify_event_fsid(event);
 	if (copy_to_user(buf, &info, sizeof(info)))
 		return -EFAULT;
 
 	buf += sizeof(info);
 	len -= sizeof(info);
-	handle.handle_type = event->fh_type;
+	handle.handle_type = fh->type;
 	handle.handle_bytes = fh_len;
 	if (copy_to_user(buf, &handle, sizeof(handle)))
 		return -EFAULT;
@@ -230,12 +233,12 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 	 * For an inline fh, copy through stack to exclude the copy from
 	 * usercopy hardening protections.
 	 */
-	fh = fanotify_event_fh(event);
+	fh_buf = fanotify_fh_buf(fh);
 	if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
-		memcpy(bounce, fh, fh_len);
-		fh = bounce;
+		memcpy(bounce, fh_buf, fh_len);
+		fh_buf = bounce;
 	}
-	if (copy_to_user(buf, fh, fh_len))
+	if (copy_to_user(buf, fh_buf, fh_len))
 		return -EFAULT;
 
 	/* Pad with 0's */
@@ -254,12 +257,14 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
 {
 	struct fanotify_event_metadata metadata;
 	struct fanotify_event *event;
+	struct path *path;
 	struct file *f = NULL;
 	int ret, fd = FAN_NOFD;
 
 	pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
 
 	event = container_of(fsn_event, struct fanotify_event, fse);
+	path = fanotify_event_path(event);
 	metadata.event_len = FAN_EVENT_METADATA_LEN;
 	metadata.metadata_len = FAN_EVENT_METADATA_LEN;
 	metadata.vers = FANOTIFY_METADATA_VERSION;
@@ -267,16 +272,12 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
 	metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
 	metadata.pid = pid_vnr(event->pid);
 
-	if (fanotify_event_has_path(event)) {
-		struct path *path = &event->path;
-
-		if (path->mnt && path->dentry) {
-			fd = create_fd(group, path, &f);
-			if (fd < 0)
-				return fd;
-		}
-	} else if (fanotify_event_has_fid(event)) {
+	if (fanotify_event_has_fid(event)) {
 		metadata.event_len += fanotify_event_info_len(event);
+	} else if (path && path->mnt && path->dentry) {
+		fd = create_fd(group, path, &f);
+		if (fd < 0)
+			return fd;
 	}
 	metadata.fd = fd;