From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]) by bombadil.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TRZt9-0007kj-8e for kexec@lists.infradead.org; Fri, 26 Oct 2012 02:43:11 +0000 Date: Fri, 26 Oct 2012 03:39:16 +0100 From: Matthew Garrett Subject: Re: Kdump with signed images Message-ID: <20121026023916.GA16762@srcf.ucam.org> References: <871ugqb4gj.fsf@xmission.com> <20121023131854.GA16496@redhat.com> <20121023145920.GD16496@redhat.com> <87fw552mb4.fsf_-_@xmission.com> <20121024173651.GE1821@redhat.com> <1351145401.18115.78.camel@falcor> <20121025141048.GD9377@redhat.com> <1351190421.18115.92.camel@falcor> <20121025185520.GA17995@redhat.com> <1351214158.18115.186.camel@falcor> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1351214158.18115.186.camel@falcor> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Mimi Zohar Cc: Dmitry Kasatkin , Kees Cook , kexec@lists.infradead.org, linux kernel mailing list , horms@verge.net.au, "Eric W. Biederman" , "H. Peter Anvin" , Roberto Sassu , Dave Young , Vivek Goyal , Khalid Aziz On Thu, Oct 25, 2012 at 09:15:58PM -0400, Mimi Zohar wrote: > On a running system, the package installer, after verifying the package > integrity, would install each file with the associated 'security.ima' > extended attribute. The 'security.evm' digital signature would be > installed with an HMAC, calculated using a system unique key. The idea isn't to prevent /sbin/kexec from being modified after installation - it's to prevent it from being possible to install a system that has a modified /sbin/kexec. Leaving any part of this up to the package installer means that it doesn't solve the problem we're trying to solve here. It must be impossible for the kernel to launch any /sbin/kexec that hasn't been signed by a trusted key that's been built into the kernel, and it must be impossible for anything other than /sbin/kexec to make the kexec system call. -- Matthew Garrett | mjg59@srcf.ucam.org _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754861Ab2JZCkH (ORCPT ); Thu, 25 Oct 2012 22:40:07 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:46156 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753125Ab2JZCkG (ORCPT ); Thu, 25 Oct 2012 22:40:06 -0400 Date: Fri, 26 Oct 2012 03:39:16 +0100 From: Matthew Garrett To: Mimi Zohar Cc: Vivek Goyal , "Eric W. Biederman" , Khalid Aziz , kexec@lists.infradead.org, horms@verge.net.au, Dave Young , "H. Peter Anvin" , linux kernel mailing list , Dmitry Kasatkin , Roberto Sassu , Kees Cook Subject: Re: Kdump with signed images Message-ID: <20121026023916.GA16762@srcf.ucam.org> References: <871ugqb4gj.fsf@xmission.com> <20121023131854.GA16496@redhat.com> <20121023145920.GD16496@redhat.com> <87fw552mb4.fsf_-_@xmission.com> <20121024173651.GE1821@redhat.com> <1351145401.18115.78.camel@falcor> <20121025141048.GD9377@redhat.com> <1351190421.18115.92.camel@falcor> <20121025185520.GA17995@redhat.com> <1351214158.18115.186.camel@falcor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1351214158.18115.186.camel@falcor> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 25, 2012 at 09:15:58PM -0400, Mimi Zohar wrote: > On a running system, the package installer, after verifying the package > integrity, would install each file with the associated 'security.ima' > extended attribute. The 'security.evm' digital signature would be > installed with an HMAC, calculated using a system unique key. The idea isn't to prevent /sbin/kexec from being modified after installation - it's to prevent it from being possible to install a system that has a modified /sbin/kexec. Leaving any part of this up to the package installer means that it doesn't solve the problem we're trying to solve here. It must be impossible for the kernel to launch any /sbin/kexec that hasn't been signed by a trusted key that's been built into the kernel, and it must be impossible for anything other than /sbin/kexec to make the kexec system call. -- Matthew Garrett | mjg59@srcf.ucam.org