Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934316AbcLNXQV (ORCPT ); Wed, 14 Dec 2016 18:16:21 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:37677 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933398AbcLNXQU (ORCPT ); Wed, 14 Dec 2016 18:16:20 -0500 Date: Wed, 14 Dec 2016 15:16:29 -0800 From: Greg Kroah-Hartman To: "Jason A. Donenfeld" Cc: LKML , kernel-hardening@lists.openwall.com Subject: Re: [kernel-hardening] [RFC 0/4] make call_usermodehelper a bit more "safe" Message-ID: <20161214231629.GA23558@kroah.com> References: <20161214185000.GA3930@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 22 On Wed, Dec 14, 2016 at 10:28:18PM +0100, Jason A. Donenfeld wrote: > Hi Greg, > > On Wed, Dec 14, 2016 at 7:50 PM, Greg KH wrote: > > So, anyone have any better ideas? Is this approach worth it? Or should > > we just go down the "whitelist" path? > > I think your approach is generally better than the whitelist path. But > maybe there's yet a third approach that involves futzing with page > permissions at runtime. I think grsec does something similar with > read_mostly function pointer structs. Namely, they make them read-only > const, and then temporarily twiddle the page permissions if it needs > to be changed while disabling preemption. There could be a particular > class of data that needs to be "opened" and "closed" in order to > modify. Seems like these strings would be a good use of that. Yes, but that's a much larger issue and if that feature ever lands, we can switch these strings over to that functionality. thanks, greg k-h