From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 26AE893D for ; Tue, 2 Aug 2016 19:14:48 +0000 (UTC) Received: from mail-io0-f172.google.com (mail-io0-f172.google.com [209.85.223.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 8C8D62A0 for ; Tue, 2 Aug 2016 19:14:47 +0000 (UTC) Received: by mail-io0-f172.google.com with SMTP id 38so222070270iol.0 for ; Tue, 02 Aug 2016 12:14:47 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1469631987.27356.48.camel@HansenPartnership.com> <20150804152622.GY30479@wotan.suse.de> <1468612258.5335.0.camel@linux.vnet.ibm.com> <1468612671.5335.5.camel@linux.vnet.ibm.com> <20160716005213.GL30372@sirena.org.uk> <1469544138.120686.327.camel@infradead.org> <14209.1469636040@warthog.procyon.org.uk> <1469636881.27356.70.camel@HansenPartnership.com> <1469637367.27356.73.camel@HansenPartnership.com> <1469648220.23563.15.camel@linux.vnet.ibm.com> From: Ard Biesheuvel Date: Tue, 2 Aug 2016 21:14:45 +0200 Message-ID: To: Andy Lutomirski Content-Type: text/plain; charset=UTF-8 Cc: James Bottomley , Mark Brown , "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] Last minute nominations: mcgrof and toshi List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 2 August 2016 at 21:08, Andy Lutomirski wrote: > On Tue, Aug 2, 2016 at 12:02 PM, Ard Biesheuvel > wrote: >> On 2 August 2016 at 20:55, Andy Lutomirski wrote: >>> On a related topic: last year or so, I argued that >>> CONFIG_MODULE_SIG_ALL and, more generally, the idea that in-tree >>> modules should be signed, is a suboptimal design. Instead, I think >>> that the kernel shoud just learn to recognize its in-tree modules by >>> hash. This would allow reproducible builds, get rid of the >>> autogenerated key, and would allow distros that don't support binary >>> modules to avoid needing the asymmetric key infrastructure at all (for >>> modules, anyway -- firmware is a different story. But a firmware >>> signing key doesn't interfere with the kernel build process the way >>> that an in-tree module signing key does.) >>> >>> On the theory that code speaks louder than vitriol, I decided to try >>> to implement it. The actual code is trivial (I expect under 50 lines >>> *total* for the compile-time and run-time parts together), but >>> convincing make to build the thing is a real pain in the arse. >>> >>> So expect code from me before KS unless I really get stuck fighting >>> kbuild. And, unless anyone objects, I intend to propose that we >>> delete CONFIG_MODULE_SIG_ALL entirely once this thing works. >>> >> >> This is exactly what I implemented for TomTom years ago, and the only >> issues I remember from the top of my head were: >> - build order: vmlinux needs to be built after the modules, but >> currently, building the modules requires vmlinux to be built already > > I am, literally right now, fighting kbuild to make this happen. I > think I got it mostly working. > >> - debug symbols: modules are stripped when installing them, and taking >> the hash needs to be done afterwards > > I don't know whether this is cleanly fixable directly. We could add a > way for distros to hook the build process so that they can insert the > strip operation in the right place. We could also have > CONFIG_STRIP_MODULES that automatically splits the debug info out from > the modules. > >> >> Then,c-ize a build time sorted list of hashes, and do a binary search >> at verification time. > > Would you believe I'm implementing exactly that algorithm? :) > Been there, done that :-)