Commit d4e1ac55 authored Jul 04, 2016 by Miklos Szeredi Committed by Sasha Levin Aug 07, 2016

ovl: handle ATTR_KILL*



[ Upstream commit b99c2d913810e56682a538c9f2394d76fca808f8 ]

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 <eguan@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

parent 69fb704c

fs/overlayfs/inode.c

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -54,6 +54,10 @@ int ovl_setattr(struct dentry dentry, struct iattr attr)
	upperdentry = ovl_dentry_upper(dentry);		upperdentry = ovl_dentry_upper(dentry);

	mutex_lock(&upperdentry->d_inode->i_mutex);		mutex_lock(&upperdentry->d_inode->i_mutex);

			if (attr->ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID))
			attr->ia_valid &= ~ATTR_MODE;

	err = notify_change(upperdentry, attr, NULL);		err = notify_change(upperdentry, attr, NULL);
	if (!err)		if (!err)
	ovl_copyattr(upperdentry->d_inode, dentry->d_inode);		ovl_copyattr(upperdentry->d_inode, dentry->d_inode);