fanotify: Add pids to events

Pass the process identifiers of the triggering processes to fanotify
listeners: this information is useful for event filtering and logging.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fs/notify/fanotify/fanotify.c

@@ -10,8 +10,9 @@ static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
 {
 	pr_debug("%s: old=%p new=%p\n", __func__, old, new);
 
-	if ((old->to_tell == new->to_tell) &&
-	    (old->data_type == new->data_type)) {
+	if (old->to_tell == new->to_tell &&
+	    old->data_type == new->data_type &&
+	    old->tgid == new->tgid) {
 		switch (old->data_type) {
 		case (FSNOTIFY_EVENT_PATH):
 			if ((old->path.mnt == new->path.mnt) &&

fs/notify/fanotify/fanotify_user.c

@@ -103,6 +103,7 @@ static ssize_t fill_event_metadata(struct fsnotify_group *group,
 	metadata->event_len = FAN_EVENT_METADATA_LEN;
 	metadata->vers = FANOTIFY_METADATA_VERSION;
 	metadata->mask = fanotify_outgoing_mask(event->mask);
+	metadata->pid = pid_vnr(event->tgid);
 	metadata->fd = create_fd(group, event);
 
 	return metadata->fd;

fs/notify/notification.c

@@ -93,6 +93,7 @@ void fsnotify_put_event(struct fsnotify_event *event)
 		BUG_ON(!list_empty(&event->private_data_list));
 
 		kfree(event->file_name);
+		put_pid(event->tgid);
 		kmem_cache_free(fsnotify_event_cachep, event);
 	}
 }
@@ -346,6 +347,7 @@ struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event)
 			return NULL;
 		}
 	}
+	event->tgid = get_pid(old_event->tgid);
 	if (event->data_type == FSNOTIFY_EVENT_PATH)
 		path_get(&event->path);
 
@@ -385,6 +387,7 @@ struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
 		event->name_len = strlen(event->file_name);
 	}
 
+	event->tgid = get_pid(task_tgid(current));
 	event->sync_cookie = cookie;
 	event->to_tell = to_tell;
 	event->data_type = data_type;

include/linux/fanotify.h

@@ -62,6 +62,7 @@ struct fanotify_event_metadata {
 	__u32 vers;
 	__s32 fd;
 	__u64 mask;
+	__s64 pid;
 } __attribute__ ((packed));
 
 /* Helper functions to deal with fanotify_event_metadata buffers */

include/linux/fsnotify_backend.h

@@ -221,6 +221,7 @@ struct fsnotify_event {
 	u32 sync_cookie;	/* used to corrolate events, namely inotify mv events */
 	char *file_name;
 	size_t name_len;
+	struct pid *tgid;
 
 	struct list_head private_data_list;	/* groups can store private data here */
 };