From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH V3 03/11] x86: Lock down IO port access when module security is enabled Date: Thu, 05 Sep 2013 08:36:51 -0700 Message-ID: <69eec644-f26f-410c-bb76-0b7695dde65c@email.android.com> 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 Return-path: In-Reply-To: <1378353524.13193.26.camel@x230> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Matthew Garrett Cc: "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org" List-Id: linux-efi@vger.kernel.org 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.