Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946025AbbEVWT0 (ORCPT ); Fri, 22 May 2015 18:19:26 -0400 Received: from mail-la0-f53.google.com ([209.85.215.53]:35823 "EHLO mail-la0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1945968AbbEVWTX (ORCPT ); Fri, 22 May 2015 18:19:23 -0400 MIME-Version: 1.0 In-Reply-To: <24757.1432332934@warthog.procyon.org.uk> References: <20150522141358.2581.qmail@ns.horizon.com> <24757.1432332934@warthog.procyon.org.uk> From: Andy Lutomirski Date: Fri, 22 May 2015 15:19:01 -0700 Message-ID: Subject: Re: Should we automatically generate a module signing key at all? To: David Howells Cc: Linus Torvalds , George Spelvin , 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: 832 Lines: 21 On Fri, May 22, 2015 at 3:15 PM, David Howells wrote: > Linus Torvalds wrote: > >> I forget the exact details of the signature ..., but for the modules >> themselves, it's just appended to the module contents. > > Yes. > >> And because the size of the certificate list is variable, you can't just >> zero it out or anything like that to make things compare equal. > > Since it's discarded at the end of boot, it could be padded significantly. If you use the hash tree approach, the size of the thing in bzImage is constant. --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/