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fanotify: prepare for implicit event flags in mark mask

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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 <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2020-07-16 11:42:14 +03:00 committed by Jan Kara
parent 3ef8665366
commit 4ed6814a91
1 changed files with 24 additions and 16 deletions
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40
fs/notify/fanotify/fanotify_user.c
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@ -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;