Commit 4ed6814a authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

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: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 3ef86653

fs/notify/fanotify/fanotify_user.c

+24 −16
Original line number Diff line number Diff line
@@ -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)

				   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;

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