1 files changed, 225 insertions, 42 deletions

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 3723f3d18d20..6b9c27548997 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -13,22 +13,40 @@
 #include <linux/wait.h>
 #include <linux/audit.h>
 #include <linux/sched/mm.h>
+#include <linux/statfs.h>
 
 #include "fanotify.h"
 
 static bool should_merge(struct fsnotify_event *old_fsn,
 			 struct fsnotify_event *new_fsn)
 {
-	struct fanotify_event_info *old, *new;
+	struct fanotify_event *old, *new;
 
 	pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
 	old = FANOTIFY_E(old_fsn);
 	new = FANOTIFY_E(new_fsn);
 
-	if (old_fsn->inode == new_fsn->inode && old->pid == new->pid &&
-	    old->path.mnt == new->path.mnt &&
-	    old->path.dentry == new->path.dentry)
-		return true;
+	if (old_fsn->inode != new_fsn->inode || old->pid != new->pid ||
+	    old->fh_type != new->fh_type || old->fh_len != new->fh_len)
+		return false;
+
+	if (fanotify_event_has_path(old)) {
+		return old->path.mnt == new->path.mnt &&
+			old->path.dentry == new->path.dentry;
+	} else if (fanotify_event_has_fid(old)) {
+		/*
+		 * We want to merge many dirent events in the same dir (i.e.
+		 * creates/unlinks/renames), but we do not want to merge dirent
+		 * events referring to subdirs with dirent events referring to
+		 * non subdirs, otherwise, user won't be able to tell from a
+		 * mask FAN_CREATE|FAN_DELETE|FAN_ONDIR if it describes mkdir+
+		 * unlink pair or rmdir+create pair of events.
+		 */
+		return (old->mask & FS_ISDIR) == (new->mask & FS_ISDIR) &&
+			fanotify_fid_equal(&old->fid, &new->fid, old->fh_len);
+	}
+
+	/* Do not merge events if we failed to encode fid */
 	return false;
 }
 
@@ -36,20 +54,22 @@ static bool should_merge(struct fsnotify_event *old_fsn,
 static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
 {
 	struct fsnotify_event *test_event;
+	struct fanotify_event *new;
 
 	pr_debug("%s: list=%p event=%p\n", __func__, list, event);
+	new = FANOTIFY_E(event);
 
 	/*
 	 * Don't merge a permission event with any other event so that we know
 	 * the event structure we have created in fanotify_handle_event() is the
 	 * one we should check for permission response.
 	 */
-	if (fanotify_is_perm_event(event->mask))
+	if (fanotify_is_perm_event(new->mask))
 		return 0;
 
 	list_for_each_entry_reverse(test_event, list, list) {
 		if (should_merge(test_event, event)) {
-			test_event->mask |= event->mask;
+			FANOTIFY_E(test_event)->mask |= new->mask;
 			return 1;
 		}
 	}
@@ -57,15 +77,44 @@ static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
 	return 0;
 }
 
+/*
+ * Wait for response to permission event. The function also takes care of
+ * freeing the permission event (or offloads that in case the wait is canceled
+ * by a signal). The function returns 0 in case access got allowed by userspace,
+ * -EPERM in case userspace disallowed the access, and -ERESTARTSYS in case
+ * the wait got interrupted by a signal.
+ */
 static int fanotify_get_response(struct fsnotify_group *group,
-				 struct fanotify_perm_event_info *event,
+				 struct fanotify_perm_event *event,
 				 struct fsnotify_iter_info *iter_info)
 {
 	int ret;
 
 	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 
-	wait_event(group->fanotify_data.access_waitq, event->response);
+	ret = wait_event_killable(group->fanotify_data.access_waitq,
+				  event->state == FAN_EVENT_ANSWERED);
+	/* Signal pending? */
+	if (ret < 0) {
+		spin_lock(&group->notification_lock);
+		/* Event reported to userspace and no answer yet? */
+		if (event->state == FAN_EVENT_REPORTED) {
+			/* Event will get freed once userspace answers to it */
+			event->state = FAN_EVENT_CANCELED;
+			spin_unlock(&group->notification_lock);
+			return ret;
+		}
+		/* Event not yet reported? Just remove it. */
+		if (event->state == FAN_EVENT_INIT)
+			fsnotify_remove_queued_event(group, &event->fae.fse);
+		/*
+		 * Event may be also answered in case signal delivery raced
+		 * with wakeup. In that case we have nothing to do besides
+		 * freeing the event and reporting error.
+		 */
+		spin_unlock(&group->notification_lock);
+		goto out;
+	}
 
 	/* userspace responded, convert to something usable */
 	switch (event->response & ~FAN_AUDIT) {
@@ -81,11 +130,11 @@ static int fanotify_get_response(struct fsnotify_group *group,
 	if (event->response & FAN_AUDIT)
 		audit_fanotify(event->response & ~FAN_AUDIT);
 
-	event->response = 0;
-
 	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
 		 group, event, ret);
-	
+out:
+	fsnotify_destroy_event(group, &event->fae.fse);
+
 	return ret;
 }
 
@@ -95,11 +144,13 @@ 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,
-				       u32 event_mask, const void *data,
-				       int data_type)
+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)
 {
 	__u32 marks_mask = 0, marks_ignored_mask = 0;
+	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS;
 	const struct path *path = data;
 	struct fsnotify_mark *mark;
 	int type;
@@ -107,14 +158,14 @@ 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 (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))
-		return 0;
+	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;
+		/* 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))
@@ -133,20 +184,106 @@ static u32 fanotify_group_event_mask(struct fsnotify_iter_info *iter_info,
 		marks_ignored_mask |= mark->ignored_mask;
 	}
 
-	if (d_is_dir(path->dentry) &&
+	test_mask = event_mask & marks_mask & ~marks_ignored_mask;
+
+	/*
+	 * dirent modification events (create/delete/move) do not carry the
+	 * child entry name/inode information. Instead, we report FAN_ONDIR
+	 * for mkdir/rmdir so user can differentiate them from creat/unlink.
+	 *
+	 * For backward compatibility and consistency, do not report FAN_ONDIR
+	 * to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR
+	 * to user in FAN_REPORT_FID mode for all event types.
+	 */
+	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
+		/* Do not report FAN_ONDIR without any event */
+		if (!(test_mask & ~FAN_ONDIR))
+			return 0;
+	} else {
+		user_mask &= ~FAN_ONDIR;
+	}
+
+	if (event_mask & FS_ISDIR &&
 	    !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
 		return 0;
 
-	return event_mask & FANOTIFY_OUTGOING_EVENTS & marks_mask &
-		~marks_ignored_mask;
+	return test_mask & user_mask;
+}
+
+static int fanotify_encode_fid(struct fanotify_event *event,
+			       struct inode *inode, gfp_t gfp,
+			       __kernel_fsid_t *fsid)
+{
+	struct fanotify_fid *fid = &event->fid;
+	int dwords, bytes = 0;
+	int err, type;
+
+	fid->ext_fh = NULL;
+	dwords = 0;
+	err = -ENOENT;
+	type = exportfs_encode_inode_fh(inode, NULL, &dwords, NULL);
+	if (!dwords)
+		goto out_err;
+
+	bytes = dwords << 2;
+	if (bytes > FANOTIFY_INLINE_FH_LEN) {
+		/* Treat failure to allocate fh as failure to allocate event */
+		err = -ENOMEM;
+		fid->ext_fh = kmalloc(bytes, gfp);
+		if (!fid->ext_fh)
+			goto out_err;
+	}
+
+	type = exportfs_encode_inode_fh(inode, fanotify_fid_fh(fid, bytes),
+					&dwords, NULL);
+	err = -EINVAL;
+	if (!type || type == FILEID_INVALID || bytes != dwords << 2)
+		goto out_err;
+
+	fid->fsid = *fsid;
+	event->fh_len = bytes;
+
+	return type;
+
+out_err:
+	pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
+			    "type=%d, bytes=%d, err=%i)\n",
+			    fsid->val[0], fsid->val[1], type, bytes, err);
+	kfree(fid->ext_fh);
+	fid->ext_fh = NULL;
+	event->fh_len = 0;
+
+	return FILEID_INVALID;
 }
 
-struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
-						 struct inode *inode, u32 mask,
-						 const struct path *path)
+/*
+ * 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)
 {
-	struct fanotify_event_info *event = NULL;
+	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 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
@@ -160,28 +297,36 @@ struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
 	memalloc_use_memcg(group->memcg);
 
 	if (fanotify_is_perm_event(mask)) {
-		struct fanotify_perm_event_info *pevent;
+		struct fanotify_perm_event *pevent;
 
 		pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
 		if (!pevent)
 			goto out;
 		event = &pevent->fae;
 		pevent->response = 0;
+		pevent->state = FAN_EVENT_INIT;
 		goto init;
 	}
 	event = kmem_cache_alloc(fanotify_event_cachep, gfp);
 	if (!event)
 		goto out;
 init: __maybe_unused
-	fsnotify_init_event(&event->fse, inode, mask);
+	fsnotify_init_event(&event->fse, inode);
+	event->mask = mask;
 	if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
 		event->pid = get_pid(task_pid(current));
 	else
 		event->pid = get_pid(task_tgid(current));
-	if (path) {
-		event->path = *path;
+	event->fh_len = 0;
+	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, id, gfp, fsid);
+	} else if (data_type == FSNOTIFY_EVENT_PATH) {
+		event->fh_type = FILEID_ROOT;
+		event->path = *((struct path *)data);
 		path_get(&event->path);
 	} else {
+		event->fh_type = FILEID_INVALID;
 		event->path.mnt = NULL;
 		event->path.dentry = NULL;
 	}
@@ -190,6 +335,29 @@ out:
 	return event;
 }
 
+/*
+ * Get cached fsid of the filesystem containing the object from any connector.
+ * All connectors are supposed to have the same fsid, but we do not verify that
+ * here.
+ */
+static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
+{
+	int type;
+	__kernel_fsid_t fsid = {};
+
+	fsnotify_foreach_obj_type(type) {
+		if (!fsnotify_iter_should_report_type(iter_info, type))
+			continue;
+
+		fsid = iter_info->marks[type]->connector->fsid;
+		if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
+			continue;
+		return fsid;
+	}
+
+	return fsid;
+}
+
 static int fanotify_handle_event(struct fsnotify_group *group,
 				 struct inode *inode,
 				 u32 mask, const void *data, int data_type,
@@ -197,14 +365,22 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 				 struct fsnotify_iter_info *iter_info)
 {
 	int ret = 0;
-	struct fanotify_event_info *event;
+	struct fanotify_event *event;
 	struct fsnotify_event *fsn_event;
+	__kernel_fsid_t fsid = {};
 
 	BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
 	BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
+	BUILD_BUG_ON(FAN_ATTRIB != FS_ATTRIB);
 	BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
 	BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
 	BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
+	BUILD_BUG_ON(FAN_MOVED_TO != FS_MOVED_TO);
+	BUILD_BUG_ON(FAN_MOVED_FROM != FS_MOVED_FROM);
+	BUILD_BUG_ON(FAN_CREATE != FS_CREATE);
+	BUILD_BUG_ON(FAN_DELETE != FS_DELETE);
+	BUILD_BUG_ON(FAN_DELETE_SELF != FS_DELETE_SELF);
+	BUILD_BUG_ON(FAN_MOVE_SELF != FS_MOVE_SELF);
 	BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
 	BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
 	BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
@@ -213,9 +389,10 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 	BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
 	BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
 
-	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 12);
+	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
 
-	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;
 
@@ -231,7 +408,11 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 			return 0;
 	}
 
-	event = fanotify_alloc_event(group, inode, mask, data);
+	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID))
+		fsid = fanotify_get_fsid(iter_info);
+
+	event = fanotify_alloc_event(group, inode, mask, data, data_type,
+				     &fsid);
 	ret = -ENOMEM;
 	if (unlikely(!event)) {
 		/*
@@ -255,7 +436,6 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 	} else if (fanotify_is_perm_event(mask)) {
 		ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event),
 					    iter_info);
-		fsnotify_destroy_event(group, fsn_event);
 	}
 finish:
 	if (fanotify_is_perm_event(mask))
@@ -275,12 +455,15 @@ static void fanotify_free_group_priv(struct fsnotify_group *group)
 
 static void fanotify_free_event(struct fsnotify_event *fsn_event)
 {
-	struct fanotify_event_info *event;
+	struct fanotify_event *event;
 
 	event = FANOTIFY_E(fsn_event);
-	path_put(&event->path);
+	if (fanotify_event_has_path(event))
+		path_put(&event->path);
+	else if (fanotify_event_has_ext_fh(event))
+		kfree(event->fid.ext_fh);
 	put_pid(event->pid);
-	if (fanotify_is_perm_event(fsn_event->mask)) {
+	if (fanotify_is_perm_event(event->mask)) {
 		kmem_cache_free(fanotify_perm_event_cachep,
 				FANOTIFY_PE(fsn_event));
 		return;