Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755927Ab3CUPgk (ORCPT ); Thu, 21 Mar 2013 11:36:40 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:24052 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754529Ab3CUPgi (ORCPT ); Thu, 21 Mar 2013 11:36:38 -0400 X-Authority-Analysis: v=2.0 cv=UN5f7Vjy c=1 sm=0 a=tLUlnkoJZcZI9ocdGARlSQ==:17 a=c11ml42nfjYA:10 a=wom5GMh1gUkA:10 a=PQXwkx6xI6AA:10 a=Rj1_iGo3bfgA:10 a=kj9zAlcOel0A:10 a=hBqU3vQJAAAA:8 a=v06FSq8qSjgA:10 a=20KFwNOVAAAA:8 a=7JgLs6tnqoPRVgF8aR0A:9 a=CjuIK1q_8ugA:10 a=jEp0ucaQiEUA:10 wl=env:18 a=tLUlnkoJZcZI9ocdGARlSQ==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 70.114.148.7 Date: Thu, 21 Mar 2013 10:37:25 -0500 From: "Serge E. Hallyn" To: Vivek Goyal Cc: Matthew Garrett , Mimi Zohar , James Morris , "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-efi@vger.kernel.org" , "kexec@lists.infradead.org" , "linux-pci@vger.kernel.org" , "Serge E. Hallyn" Subject: Re: [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL Message-ID: <20130321153725.GA3656@austin.hallyn.com> References: <1363797717.2580.10.camel@falcor1.watson.ibm.com> <1363798166.2553.29.camel@x230.sbx07502.somerma.wayport.net> <1363802506.2580.55.camel@falcor1.watson.ibm.com> <1363803158.2553.33.camel@x230.sbx07502.somerma.wayport.net> <1363806968.2580.86.camel@falcor1.watson.ibm.com> <1363811856.2553.37.camel@x230.sbx07502.somerma.wayport.net> <1363813877.2580.120.camel@falcor1.watson.ibm.com> <1363814289.2553.41.camel@x230.sbx07502.somerma.wayport.net> <20130321134348.GA3934@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130321134348.GA3934@redhat.com> 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 Content-Length: 1229 Lines: 26 Quoting Vivek Goyal (vgoyal@redhat.com): ... > Giving CAP_MODIFY_KERNEL to processess upon signature verification > will simplify things a bit. > > Only thing is that signature verification alone is not sufficient. We > also need to make sure after signature verification executable can > not be modified in memory in any way. So that means atleast couple of > things. Also what about context? If I construct a mounts namespace a certain way, can I trick this executable into loading an old singed bzImage that I had laying around? ISTM the only sane thing to do, if you're going down this road, is to have CAP_MODIFIY_KERNEL pulled from bounding set for everyone except a getty started by init on ttyS0. Then log in on serial to update. Or run a damon with CAP_MODIFIY_KERNEL which listens to a init_net_ns netlink socket for very basic instructions, like "find and install latest signed bzImage in /boot". Then you can at least trust that /boot for that daemon is not faked. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/