From 4ed6814a91cc71202e3de12cd1cb7cc59f3cee57 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 16 Jul 2020 11:42:14 +0300 Subject: [PATCH] fanotify: prepare for implicit event flags in mark mask So far, all flags that can be set in an fanotify mark mask can be set explicitly by a call to fanotify_mark(2). Prepare for defining implicit event flags that cannot be set by user with fanotify_mark(2), similar to how inotify/dnotify implicitly set the FS_EVENT_ON_CHILD flag. Implicit event flags cannot be removed by user and mark gets destroyed when only implicit event flags remain in the mask. Link: https://lore.kernel.org/r/20200716084230.30611-7-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- fs/notify/fanotify/fanotify_user.c | 40 +++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 16 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 6d30beb..ab974cd 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -656,12 +656,13 @@ out: } static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, - __u32 mask, - unsigned int flags, - int *destroy) + __u32 mask, unsigned int flags, + __u32 umask, int *destroy) { __u32 oldmask = 0; + /* umask bits cannot be removed by user */ + mask &= ~umask; spin_lock(&fsn_mark->lock); if (!(flags & FAN_MARK_IGNORED_MASK)) { oldmask = fsn_mark->mask; @@ -669,7 +670,13 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, } else { fsn_mark->ignored_mask &= ~mask; } - *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask); + /* + * We need to keep the mark around even if remaining mask cannot + * result in any events (e.g. mask == FAN_ONDIR) to support incremenal + * changes to the mask. + * Destroy mark when only umask bits remain. + */ + *destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask); spin_unlock(&fsn_mark->lock); return mask & oldmask; @@ -677,7 +684,7 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, static int fanotify_remove_mark(struct fsnotify_group *group, fsnotify_connp_t *connp, __u32 mask, - unsigned int flags) + unsigned int flags, __u32 umask) { struct fsnotify_mark *fsn_mark = NULL; __u32 removed; @@ -691,7 +698,7 @@ static int fanotify_remove_mark(struct fsnotify_group *group, } removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, - &destroy_mark); + umask, &destroy_mark); if (removed & fsnotify_conn_mask(fsn_mark->connector)) fsnotify_recalc_mask(fsn_mark->connector); if (destroy_mark) @@ -707,25 +714,26 @@ static int fanotify_remove_mark(struct fsnotify_group *group, static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt, __u32 mask, - unsigned int flags) + unsigned int flags, __u32 umask) { return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, - mask, flags); + mask, flags, umask); } static int fanotify_remove_sb_mark(struct fsnotify_group *group, - struct super_block *sb, __u32 mask, - unsigned int flags) + struct super_block *sb, __u32 mask, + unsigned int flags, __u32 umask) { - return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, flags); + return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, + flags, umask); } static int fanotify_remove_inode_mark(struct fsnotify_group *group, struct inode *inode, __u32 mask, - unsigned int flags) + unsigned int flags, __u32 umask) { return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, - flags); + flags, umask); } static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, @@ -1175,13 +1183,13 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, case FAN_MARK_REMOVE: if (mark_type == FAN_MARK_MOUNT) ret = fanotify_remove_vfsmount_mark(group, mnt, mask, - flags); + flags, 0); else if (mark_type == FAN_MARK_FILESYSTEM) ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, - flags); + flags, 0); else ret = fanotify_remove_inode_mark(group, inode, mask, - flags); + flags, 0); break; default: ret = -EINVAL; -- 2.7.4