From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA18AC77B7D for ; Sun, 14 May 2023 19:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229929AbjENTL6 (ORCPT ); Sun, 14 May 2023 15:11:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229611AbjENTL5 (ORCPT ); Sun, 14 May 2023 15:11:57 -0400 Received: from cavan.codon.org.uk (irc.codon.org.uk [IPv6:2a00:1098:84:22e::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 093A61984; Sun, 14 May 2023 12:11:53 -0700 (PDT) Received: by cavan.codon.org.uk (Postfix, from userid 1000) id 9869140A84; Sun, 14 May 2023 20:11:50 +0100 (BST) Date: Sun, 14 May 2023 20:11:50 +0100 From: Matthew Garrett To: Eric Biggers Cc: Andrew Cooper , Ard Biesheuvel , Ross Philipson , linux-kernel@vger.kernel.org, x86@kernel.org, linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org, kexec@lists.infradead.org, linux-efi@vger.kernel.org, dpsmith@apertussolutions.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, James.Bottomley@hansenpartnership.com, luto@amacapital.net, nivedita@alum.mit.edu, kanth.ghatraju@oracle.com, trenchboot-devel@googlegroups.com Subject: Re: [PATCH v6 06/14] x86: Add early SHA support for Secure Launch early measurements Message-ID: <20230514191150.GA17168@srcf.ucam.org> References: <20230504145023.835096-1-ross.philipson@oracle.com> <20230504145023.835096-7-ross.philipson@oracle.com> <20230510012144.GA1851@quark.localdomain> <20230512110455.GD14461@srcf.ucam.org> <20230512112847.GF14461@srcf.ucam.org> <4acf414e-67e7-c964-566b-a5e657e9d1bb@citrix.com> <20230514181817.GA9528@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230514181817.GA9528@sol.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Sun, May 14, 2023 at 11:18:17AM -0700, Eric Biggers wrote: > On Fri, May 12, 2023 at 01:24:22PM +0100, Andrew Cooper wrote: > > You're suggesting that because Linux has been slow to take D-RTM over > > the past decade, you're going to intentionally break people with older > > hardware just because you don't feel like using an older algorithm? > > > > That's about the worst possible reason to not take support. > > > > There really are people in the world with older TPM 1.2 systems where > > this D-RTM using SHA1 only is an improvement over using the incumbent tboot. > > > > ~Andrew > > This patchset is proposing a new kernel feature. So by definition, there are no > existing users of it that can be broken. The patchset reimplements a more extensible version of an existing feature which people already consume, and presumably people will be encouraged to transition to it. There is plenty of hardware that supports this feature that only implements SHA-1. If you want to propose that the kernel not implement any functionality that uses deprecated hash algorithms then that seems like a larger conversation rather than one that should focus on a single pachset.