Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761762Ab2KAOmV (ORCPT ); Thu, 1 Nov 2012 10:42:21 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:37739 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761301Ab2KAOmT (ORCPT ); Thu, 1 Nov 2012 10:42:19 -0400 Message-ID: <1351780935.2391.58.camel@dabdike.int.hansenpartnership.com> Subject: Re: [RFC] Second attempt at kernel secure boot support From: James Bottomley To: Eric Paris Cc: Jiri Kosina , Oliver Neukum , Chris Friesen , Alan Cox , Matthew Garrett , Josh Boyer , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org Date: Thu, 01 Nov 2012 14:42:15 +0000 In-Reply-To: References: <1348152065-31353-1-git-send-email-mjg@redhat.com> <2548314.3caaFsMVg6@linux-lqwf.site> <50919EED.3020601@genband.com> <36538307.gzWq1oO7Kg@linux-lqwf.site> <1351760905.2391.19.camel@dabdike.int.hansenpartnership.com> <1351762703.2391.31.camel@dabdike.int.hansenpartnership.com> <1351763954.2391.37.camel@dabdike.int.hansenpartnership.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2269 Lines: 49 On Thu, 2012-11-01 at 10:29 -0400, Eric Paris wrote: > On Thu, Nov 1, 2012 at 5:59 AM, James Bottomley > wrote: > > > But that doesn't really help me: untrusted root is an oxymoron. > > Imagine you run windows and you've never heard of Linux. You like > that only windows kernels can boot on your box and not those mean > nasty hacked up malware kernels. Now some attacker manages to take > over your box because you clicked on that executable for young models > in skimpy bathing suits. That executable rewrote your bootloader to > launch a very small carefully crafted Linux environment. This > environment does nothing but launch a perfectly valid signed Linux > kernel, which gets a Windows environment all ready to launch after > resume and goes to sleep. Now you have to hit the power button twice > every time you turn on your computer, weird, but Windows comes up, and > secureboot is still on, so you must be safe! So you're going back to the root exploit problem? I thought that was debunked a few emails ago in the thread? Your attack vector isn't plausible because for the suspend attack to work, the box actually has to be running Linux by default ... I think the admin of that box might notice if it suddenly started running windows ... > In this case we have a completely 'untrusted' root inside Linux. From > the user PoV root and Linux are both malware. Notice the EXACT same > attack would work launching rootkit'd Linux from Linux. So don't > pretend not to care about Windows. It's just that launching malware > Linux seems like a reason to get your key revoked. We don't want > signed code which can be used as an attack vector on ourselves or on > others. > > That make sense? Not really, no. A windows attack vector is a pointless abstraction because we're talking about securing Linux and your vector requires a Linux attack for the windows compromise ... let's try to keep on point to how we're using this feature to secure Linux. James -- 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/