Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946028AbbEVUpD (ORCPT ); Fri, 22 May 2015 16:45:03 -0400 Received: from mail-la0-f50.google.com ([209.85.215.50]:34011 "EHLO mail-la0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1945990AbbEVUo7 (ORCPT ); Fri, 22 May 2015 16:44:59 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150522141358.2581.qmail@ns.horizon.com> From: Andy Lutomirski Date: Fri, 22 May 2015 13:44:37 -0700 Message-ID: Subject: Re: Should we automatically generate a module signing key at all? To: Linus Torvalds Cc: George Spelvin , David Howells , David Woodhouse , Linux Kernel Mailing List , LSM List , petkan@mip-labs.com, "Theodore Ts'o" , Mimi Zohar Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1266 Lines: 29 On Fri, May 22, 2015 at 1:40 PM, Linus Torvalds wrote: > On Fri, May 22, 2015 at 7:13 AM, George Spelvin wrote: >> >> 1) Create a tool to canonicalize the kernel and modules, >> stripping out the signatures before comparing them. This has >> precedent in the way the prelink tool can un-prelink binaries >> so that hashes can be verified. > > So I'd obviously prefer this, so that we have just one model for verification. > In the threat model where module signatures matter in the first place [1], this prevents reproducible builds from serving their purpose. I can build a kernel with a fresh signing key and throw away the private key. You can build a canonically identical kernel with a private key that you keep. A third party using mine is safe, but a third party using yours is unsafe, even though the whole packages canonicalize to exactly the same bytes. [1] I still think this is a silly threat model, but many people disagree with me. --Andy -- 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/