This adds logic in order to support restarting pending permission events. In terms of implementation, we reinsert events into notification queue so they can be reprocessed on subsequent read ops (an alternative is restarting fsnotify call [1]). Restart will be triggered upon queue fd release. [1] https://lore.kernel.org/linux-fsdevel/2ogjwnem7o3jwukzoq2ywnxha5ljiqnjnr4o4b5xvdvwpbyeac@v4i7jygvk7fj/2-0001-fanotify-Add-support-for-resending-unanswered-permis.patch Suggested-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/linux-fsdevel/sx5g7pmkchjqucfbzi77xh7wx4wua5nteqi5bsa2hfqgxua2a2@v7x6ja3gsirn/ Signed-off-by: Ibrahim Jirdeh <ibrahimjirdeh@xxxxxxxx> --- fs/notify/fanotify/fanotify.c | 4 +-- fs/notify/fanotify/fanotify.h | 6 ++++ fs/notify/fanotify/fanotify_user.c | 57 ++++++++++++++++++++++++------ 3 files changed, 55 insertions(+), 12 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index bfe884d624e7..6f5f43a3e6bd 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -179,7 +179,7 @@ static bool fanotify_should_merge(struct fanotify_event *old, #define FANOTIFY_MAX_MERGE_EVENTS 128 /* and the list better be locked by something too! */ -static int fanotify_merge(struct fsnotify_group *group, +int fanotify_merge(struct fsnotify_group *group, struct fsnotify_event *event) { struct fanotify_event *old, *new = FANOTIFY_E(event); @@ -904,7 +904,7 @@ static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info) /* * Add an event to hash table for faster merge. */ -static void fanotify_insert_event(struct fsnotify_group *group, +void fanotify_insert_event(struct fsnotify_group *group, struct fsnotify_event *fsn_event) { struct fanotify_event *event = FANOTIFY_E(fsn_event); diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index b78308975082..c0dffbc3370d 100644 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -550,3 +550,9 @@ static inline u32 fanotify_get_response_errno(int res) { return (res >> FAN_ERRNO_SHIFT) & FAN_ERRNO_MASK; } + +extern void fanotify_insert_event(struct fsnotify_group *group, + struct fsnotify_event *fsn_event); + +extern int fanotify_merge(struct fsnotify_group *group, + struct fsnotify_event *event); diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index b192ee068a7a..01d273d35936 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1000,6 +1000,51 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t return count; } +static void clear_queue(struct file *file, bool restart_events) +{ + struct fsnotify_group *group = file->private_data; + struct fsnotify_event *fsn_event; + int insert_ret; + + /* + * Clear all pending permission events from the access_list. If + * restart is requested, move them back into the notification queue + * for reprocessing, otherwise simulate a reply from userspace. + */ + spin_lock(&group->notification_lock); + while (!list_empty(&group->fanotify_data.access_list)) { + struct fanotify_perm_event *event; + + event = list_first_entry(&group->fanotify_data.access_list, + struct fanotify_perm_event, + fae.fse.list); + list_del_init(&event->fae.fse.list); + + if (restart_events) { + // requeue the event + spin_unlock(&group->notification_lock); + fsn_event = &event->fae.fse; + + insert_ret = fsnotify_insert_event( + group, fsn_event, fanotify_merge, + fanotify_insert_event); + if (insert_ret) { + /* + * insertion for permission events can fail if group itself + * is being shutdown. In this case, simply reply ALLOW for + * the event. + */ + spin_lock(&group->notification_lock); + finish_permission_event(group, event, FAN_ALLOW, NULL); + } + } else { + finish_permission_event(group, event, FAN_ALLOW, NULL); + } + spin_lock(&group->notification_lock); + } + spin_unlock(&group->notification_lock); +} + static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; @@ -1016,22 +1061,14 @@ static int fanotify_release(struct inode *ignored, struct file *file) * Process all permission events on access_list and notification queue * and simulate reply from userspace. */ - spin_lock(&group->notification_lock); - while (!list_empty(&group->fanotify_data.access_list)) { - struct fanotify_perm_event *event; - - event = list_first_entry(&group->fanotify_data.access_list, - struct fanotify_perm_event, fae.fse.list); - list_del_init(&event->fae.fse.list); - finish_permission_event(group, event, FAN_ALLOW, NULL); - spin_lock(&group->notification_lock); - } + clear_queue(file, false); /* * Destroy all non-permission events. For permission events just * dequeue them and set the response. They will be freed once the * response is consumed and fanotify_get_response() returns. */ + spin_lock(&group->notification_lock); while ((fsn_event = fsnotify_remove_first_event(group))) { struct fanotify_event *event = FANOTIFY_E(fsn_event); -- 2.47.3
