Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755307Ab3IZA1e (ORCPT ); Wed, 25 Sep 2013 20:27:34 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:35695 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992Ab3IZA1c (ORCPT ); Wed, 25 Sep 2013 20:27:32 -0400 Date: Thu, 26 Sep 2013 02:27:30 +0200 From: Pavel Machek To: James Bottomley Cc: Alan Stern , David Howells , "Lee, Chun-Yi" , 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 , Josh Boyer , Vojtech Pavlik , Matt Fleming , Greg KH , JKosina@suse.com, Rusty Russell , Herbert Xu , "David S. Miller" , "H. Peter Anvin" , Michal Marek , Gary Lin , Vivek Goyal , "Lee, Chun-Yi" Subject: Re: [RFC V4 PATCH 00/15] Signature verification of hibernate snapshot Message-ID: <20130926002730.GA26857@amd.pavel.ucw.cz> References: <1380147414.18835.36.camel@dabdike.int.hansenpartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1380147414.18835.36.camel@dabdike.int.hansenpartnership.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1832 Lines: 44 On Wed 2013-09-25 15:16:54, James Bottomley wrote: > On Wed, 2013-09-25 at 17:25 -0400, Alan Stern wrote: > > 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. > > The reason is the desire to validate that the previous kernel created > something which it passed on to the current kernel (in this case, the > hibernation image) untampered with. To do that, something must be > passed to the prior kernel that can be validated but *not* recreated by > the current kernel. I don't get this. Why is it important that current kernel can't recreate the signature? Current kernel is not considered malicious (if it were, you have worse problems). Pavel PS: And yes, it would be nice to have Documentation/power/swsusp-uefi.txt (or something) explaining the design. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/