From b99c2d913810e56682a538c9f2394d76fca808f8 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 4 Jul 2016 16:49:48 +0200 Subject: [PATCH] ovl: handle ATTR_KILL* Before 4bacc9c9234c ("overlayfs: Make f_path...") file->f_path pointed to the underlying file, hence suid/sgid removal on write worked fine. After that patch file->f_path pointed to the overlay file, and the file mode bits weren't copied to overlay_inode->i_mode. So the suid/sgid removal simply stopped working. The fix is to copy the mode bits, but then ovl_setattr() needs to clear ATTR_MODE to avoid the BUG() in notify_change(). So do this first, then in the next patch copy the mode. Reported-by: Eryu Guan Signed-off-by: Miklos Szeredi Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay") Cc: --- fs/overlayfs/inode.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index c831c2e5f803..1233992a7c47 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -80,6 +80,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) goto out_drop_write; } + if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) + attr->ia_valid &= ~ATTR_MODE; + inode_lock(upperdentry->d_inode); err = notify_change(upperdentry, attr, NULL); if (!err)