Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754732Ab3IEPhK (ORCPT ); Thu, 5 Sep 2013 11:37:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40453 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753455Ab3IEPhH (ORCPT ); Thu, 5 Sep 2013 11:37:07 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <1378353524.13193.26.camel@x230> References: <1378252218-18798-1-git-send-email-matthew.garrett@nebula.com> <1378252218-18798-4-git-send-email-matthew.garrett@nebula.com> <5227FFE8.5050102@zytor.com> <1378353524.13193.26.camel@x230> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH V3 03/11] x86: Lock down IO port access when module security is enabled From: "H. Peter Anvin" Date: Thu, 05 Sep 2013 08:36:51 -0700 To: Matthew Garrett CC: "linux-kernel@vger.kernel.org" , "linux-efi@vger.kernel.org" , "keescook@chromium.org" Message-ID: <69eec644-f26f-410c-bb76-0b7695dde65c@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1235 Lines: 30 Sigh. That capability really is fscked up. Matthew Garrett wrote: >On Wed, 2013-09-04 at 20:52 -0700, H. Peter Anvin wrote: >> On 09/03/2013 04:50 PM, Matthew Garrett wrote: >> > IO port access would permit users to gain access to PCI >configuration >> > registers, which in turn (on a lot of hardware) give access to MMIO >register >> > space. This would potentially permit root to trigger arbitrary DMA, >so lock >> > it down by default. >> > >> > Signed-off-by: Matthew Garrett >> >> Seriously... just deny CAP_SYS_RAWIO to any system in secure mode. > >No. CAP_SYS_RAWIO blocks things that we don't want blocked (x86 >microcode updates, various disk ioctls, *device firmware uploads* and a >few others) - the semantics just don't match. We could relax those >permissions, but then we'd potentially break someone else's security >considerations. -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- 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/