From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751235Ab3FGEVA (ORCPT ); Fri, 7 Jun 2013 00:21:00 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56421 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737Ab3FGEU7 (ORCPT ); Fri, 7 Jun 2013 00:20:59 -0400 Date: Thu, 6 Jun 2013 21:21:31 -0700 From: Greg Kroah-Hartman To: Ming Lei Cc: linux-kernel@vger.kernel.org, Takashi Iwai Subject: Re: [RFC PATCH v1 4/4] firmware loader: don't allow to request firmware via relative path Message-ID: <20130607042131.GC3603@kroah.com> References: <1370520110-32293-1-git-send-email-ming.lei@canonical.com> <1370520110-32293-5-git-send-email-ming.lei@canonical.com> <20130606194847.GB4526@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 07, 2013 at 09:30:09AM +0800, Ming Lei wrote: > On Fri, Jun 7, 2013 at 3:48 AM, Greg Kroah-Hartman > wrote: > > On Thu, Jun 06, 2013 at 08:01:50PM +0800, Ming Lei wrote: > >> It isn't a good pratice to request firmware via relative path, also > >> might have security issue, so don't do it. > > > > What would the security issue be? You are letting the person who build > > the kernel specify this, so they can put whatever they want in here, a > > '..' isn't going to keep them from being able to do "bad" things if they > > really want to. > > In VM case, guest kernel might access host filesystem files via this trick, > but not sure if it is possible. How can a ".." do anything with guest kernels that total control over a path not do? thanks, greg k-h