From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756971Ab3APS2V (ORCPT ); Wed, 16 Jan 2013 13:28:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:32460 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756194Ab3APS2U (ORCPT ); Wed, 16 Jan 2013 13:28:20 -0500 Date: Wed, 16 Jan 2013 13:28:04 -0500 From: Vivek Goyal To: Mimi Zohar Cc: "Eric W. Biederman" , linux-kernel@vger.kernel.org, pjones@redhat.com, hpa@zytor.com, dhowells@redhat.com, jwboyer@redhat.com, Dmitry Kasatkin , Andrew Morton , linux-security-module@vger.kernel.org Subject: Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary Message-ID: <20130116182804.GF29845@redhat.com> References: <1358285695-26173-1-git-send-email-vgoyal@redhat.com> <1358285695-26173-3-git-send-email-vgoyal@redhat.com> <871udloiku.fsf@xmission.com> <1358312159.4593.37.camel@falcor1> <87wqvdli1o.fsf@xmission.com> <1358344859.4593.66.camel@falcor1> <20130116144836.GB29845@redhat.com> <1358350391.4593.112.camel@falcor1> <20130116163453.GD29845@redhat.com> <1358359715.4593.146.camel@falcor1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1358359715.4593.146.camel@falcor1> 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 Wed, Jan 16, 2013 at 01:08:35PM -0500, Mimi Zohar wrote: > On Wed, 2013-01-16 at 11:34 -0500, Vivek Goyal wrote: > > > I read the comment in ima_bprm_check() being called from security_bprm_check(). > > It says that files already open for write can't executed and files already > > open for exec can't be open for writes. That's fine. > > > > I was worried about anonymous pages being modified on swap and then > > faulted back in. It is not necessarily signature verification but making > > sure signed processes memory is not modified later by any unsigned process > > in anyway. And that includes disabling ptrace too. > > > > So IMA stuff does not do anything to protect against process memory being > > modified using ptrace or by playing tricks with swap. > > > I am not sure what will happen if I can bypass the file system and directly > > write on a disk block and modify executable. (Assuming one can get block > > information somehow). Does anything protect such modification? Will IMA > > detect it? > > Sorry, this is out of scope for IMA. Dmitry has looked into this, but > I'm not sure where it stands at the moment. Ok, so that's one reason that why I wrote these patcehs. IMA currently is not doing following things to make sure address space of signed images is not modified by others. - Protecting against modifications to pages on swap. - Protecting against modifications by ptrace. - Protecting against modifications which bypassed filesystem and directly wrote to the block. Locking down all the pages of signed binaries in memory hopefully should solve above problems. Thanks Vivek