From b82c78948a5311ca3952900dffbee5c932c2d03b 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* commit b99c2d913810e56682a538c9f2394d76fca808f8 upstream. 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: Eric Schultz Cc: Eric Hameleers [backported by Eric Hameleers as seen in https://bugzilla.kernel.org/show_bug.cgi?id=150711] Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/inode.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 0597820f5d9d..4f729ffff75d 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -63,6 +63,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) if (!err) { upperdentry = ovl_dentry_upper(dentry); + if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) + attr->ia_valid &= ~ATTR_MODE; + mutex_lock(&upperdentry->d_inode->i_mutex); err = notify_change(upperdentry, attr, NULL); if (!err) -- 2.34.1