From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from e1.ny.us.ibm.com ([32.97.182.141]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TRooq-0001TP-Ew for kexec@lists.infradead.org; Fri, 26 Oct 2012 18:39:45 +0000 Received: from /spool/local by e1.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 26 Oct 2012 14:39:41 -0400 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id AEFD36E8041 for ; Fri, 26 Oct 2012 14:39:39 -0400 (EDT) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q9QIddll324410 for ; Fri, 26 Oct 2012 14:39:39 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q9QIdcns005625 for ; Fri, 26 Oct 2012 14:39:39 -0400 Message-ID: <1351276649.18115.217.camel@falcor> Subject: Re: Kdump with signed images From: Mimi Zohar Date: Fri, 26 Oct 2012 14:37:29 -0400 In-Reply-To: <20121026170609.GB24687@redhat.com> References: <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> <20121026023916.GA16762@srcf.ucam.org> <20121026170609.GB24687@redhat.com> Mime-Version: 1.0 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: Vivek Goyal Cc: Roberto Sassu , Dmitry Kasatkin , Kees Cook , kexec@lists.infradead.org, linux kernel mailing list , horms@verge.net.au, "Eric W. Biederman" , "H. Peter Anvin" , Matthew Garrett , Dave Young , Khalid Aziz On Fri, 2012-10-26 at 13:06 -0400, Vivek Goyal wrote: > On Fri, Oct 26, 2012 at 03:39:16AM +0100, Matthew Garrett wrote: > > 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. > > I am kind of lost now so just trying to summarize whatever I have > learned so far from this thread. Thanks for summarizing. > - So say we can sign /sbin/kexec at build time and distros can do that. > - Verify the signature at exec time using kernel keyring and if > verification happens successfully, say process gains extra capability. > - Use this new capability to determine whether kexec_load() will be > successful or not. > > Even if we can do all this, it still has the issue of being able to > stop the process in user space and replace the code at run time > and be able to launch unsigned kernel. > > So until and unless we have a good solution to verify application's > integrity/authneticity at the time of kexec_load() system call we > still have the problem. And I don't think we have come up with a > solution for that yet (until and unless I missed something). > > Thanks > Vivek > Agreed, you need a new LSM/integrity hook. thanks, Mimi _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec