From: David Lang Subject: Re: [PATCH 0/6] MODSIGN: Kernel module signing Date: Thu, 15 Feb 2007 12:01:22 -0800 (PST) Message-ID: References: <20070214190938.6438.15091.stgit@warthog.cambridge.redhat.com> <32081.1171560770@redhat.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: David Howells , torvalds@osdl.org, akpm@osdl.org, herbert.xu@redhat.com, linux-kernel@vger.kernel.org, davej@redhat.com, arjan@infradead.org, linux-crypto@vger.kernel.org To: Roman Zippel Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Thu, 15 Feb 2007, Roman Zippel wrote: > On Thu, 15 Feb 2007, David Howells wrote: > >> It is possible to protect /dev/mem and /dev/kmem or make them unavailable and >> it is possible to protect the kernel's memory whilst it is running (provided >> you don't have nommu or broken hardware and you don't let userspace concoct any >> DMA request it likes) which mostly closes those other vectors I mentioned. >> This isn't something I intended to look at with this patch. Those are separate >> holes. > > Exactly and as long as there are these holes, these patches are only > kernel bloat. The simple verification can also be done in userspace and > module signing offers no real security. > What real value do these patches provide, that can't be reached via other > means? Who else than distributions would be interested in this? Pretty > much any use you initially mentioned can be done in simpler ways, e.g. > anyone afraid of modules simply disables module loading completely. this issue, and these holes keep comeing up in discussions, why can't these holes be closed? I seem to remember seeing patches that would remove /dev/kmem being sent to the list, but they weren't accepted into the kernel (and I seem to remember people being against the concept of removeing them, not against techincal details of the patches. but this was many years ago) at one point I remember hearing that X required raw /dev/kmem, but for servers you don't need/want X anyway, so this is a useful option even if X doesn't get fixed. David Lang