ovl: Copy up underlying inode's ->i_mode to overlay inode

rhvgoyal · Miklos Szeredi · commit 07a2daab49c5 · 2016-07-04T16:49:48.000+02:00
Right now when a new overlay inode is created, we initialize overlay inode's ->i_mode from underlying inode ->i_mode but we retain only file type bits (S_IFMT) and discard permission bits. This patch changes it and retains permission bits too. This should allow overlay to do permission checks on overlay inode itself in task context. [SzM] It also fixes clearing suid/sgid bits on write. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reported-by: Eryu Guan <eguan@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: 4bacc9c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay") Cc: <stable@vger.kernel.org>
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
@@ -413,12 +413,11 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
 	if (!inode)
 		return NULL;
 
-	mode &= S_IFMT;
-
 	inode->i_ino = get_next_ino();
 	inode->i_mode = mode;
 	inode->i_flags |= S_NOATIME | S_NOCMTIME;
 
+	mode &= S_IFMT;
 	switch (mode) {
 	case S_IFDIR:
 		inode->i_private = oe;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
@@ -187,6 +187,7 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
 {
 	to->i_uid = from->i_uid;
 	to->i_gid = from->i_gid;
+	to->i_mode = from->i_mode;
 }
 
 /* dir.c */

Original file line number	Diff line number	Diff line change
`@@ -187,6 +187,7 @@ static inline void ovl_copyattr(struct inode from, struct inode to)`
`187`	`187`	`{`
`188`	`188`	`to->i_uid = from->i_uid;`
`189`	`189`	`to->i_gid = from->i_gid;`
	`190`	`+ to->i_mode = from->i_mode;`
`190`	`191`	`}`
`191`	`192`
`192`	`193`	`/* dir.c */`