Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754982Ab3IZCTW (ORCPT ); Wed, 25 Sep 2013 22:19:22 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:56672 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753625Ab3IZCTU (ORCPT ); Wed, 25 Sep 2013 22:19:20 -0400 Subject: Re: [RFC V4 PATCH 00/15] Signature verification of hibernate snapshot From: joeyli To: Alan Stern Cc: David Howells , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org, opensuse-kernel@opensuse.org, "Rafael J. Wysocki" , Matthew Garrett , Len Brown , Pavel Machek , Josh Boyer , Vojtech Pavlik , Matt Fleming , James Bottomley , Greg KH , JKosina@suse.com, Rusty Russell , Herbert Xu , "David S. Miller" , "H. Peter Anvin" , Michal Marek , Gary Lin , Vivek Goyal In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Thu, 26 Sep 2013 10:19:17 +0800 Message-ID: <1380161957.32302.42.camel@linux-s257.site> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2181 Lines: 57 於 三，2013-09-25 於 17:25 -0400，Alan Stern 提到： > On Wed, 25 Sep 2013, David Howells wrote: > > > I have pushed some keyrings patches that will likely affect this to: > > > > http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=keys-devel > > > > I intend to ask James to pull these into his next branch. If he's happy to do > > so, I can look at pulling at least your asymmetric keys patch on top of them. > > This suggests a point that I raised at the Linux Plumbers conference: > > Why are asymmetric keys used for verifying the hibernation image? It > seems that a symmetric key would work just as well. And it would be a > lot quicker to generate, because it wouldn't need any high-precision > integer computations. > > Alan Stern > > Per my understood, it's like add salt to snapshot when generate signature, then remove the salt when store the snapshot to swap. (or pass snapshot to userland). Let me explain the symmetric key solution base on my understand: + EFI stub kernel generate a hash value from a random seed, then store it to EFi boot varaible. It should protected by UEFI secure boot environment. + When hibernate launched: - Kernel create the snapshot image of memory. It's included the random hash value(salt) that generated in EFI stub stage. - Then kernel hash the snapshot image, put the hash to snapshot header, just like current asymmetric keys solution. - Kernel erase the salt in snapshot image before it go to swap or pass to userspace tool. + When hibernate resume: - Kernel or userspace tool load the snapshot(without salt) from swap to temporary memory space. - Kernel fill the salt back to snapshot image in memory, hash it. - Kernel compare the hash with the hash that put in snapshot header. - Verification done! The follow-up action as current solution. Please current me if I missed anything. Thanks a lot! Joey Lee -- 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/