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 A9B14C7EE26 for ; Fri, 12 May 2023 18:17:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230049AbjELSR0 (ORCPT ); Fri, 12 May 2023 14:17:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237885AbjELSRZ (ORCPT ); Fri, 12 May 2023 14:17:25 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 262BAE50; Fri, 12 May 2023 11:17:24 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1683915442; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XrXy+JN0FIVOyWDkqWfN4fNFGJKhfjsBfYB8oPd1Irc=; b=Y1yV+uoB6fx9Yhns9dAWVlJGWQcpCyKUdFqEJpQFLS+uZwOmtwgY1IB7cCtCgtxfmPGM1E RHrqBI7OIhWNpaJ+CT1K/m6a4VffRvAuFtfHtrg7DktrfeG+F9YVJHF7UonTQXVwvcsBl6 fwWaMINw9X4exjYSkh7wAm8lwsDrh0WOQX+mbJOdD265nOu21snUkPIxGI0rNIX+vxZ0tL X+l8YlFUwQAgRpK9HF7mCTycfV9zp1QIHWgo2bUoyfvj1OMI4jvyn6K01GFgbQtASecGVq 79hQECeceglkJFJGCFpuG4MjTbxbTos+68fX3FuBrYHE2tg11v8+D1uwq2vfww== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1683915442; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XrXy+JN0FIVOyWDkqWfN4fNFGJKhfjsBfYB8oPd1Irc=; b=jDQpibUvU/KTnZJH0KZt1sWuLoNTBcIE9OnnjHaZumYLz9yLuYhZiNO6B97Xnp9pWJX6Gc vTJozK43qwl7qIBw== To: Matthew Garrett Cc: Ard Biesheuvel , Eric Biggers , 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, 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 In-Reply-To: <20230512161318.GA18400@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> <87pm75bs3v.ffs@tglx> <20230512161318.GA18400@srcf.ucam.org> Date: Fri, 12 May 2023 20:17:21 +0200 Message-ID: <873541bej2.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Fri, May 12 2023 at 17:13, Matthew Garrett wrote: > On Fri, May 12, 2023 at 03:24:04PM +0200, Thomas Gleixner wrote: >> On Fri, May 12 2023 at 12:28, Matthew Garrett wrote: >> > Unless we assert that SHA-1 events are unsupported, it seems a bit odd >> > to force a policy on people who have both banks enabled. People with >> > mixed fleets are potentially going to be dealing with SHA-1 measurements >> > for a while yet, and while there's obviously a security benefit in using >> > SHA-2 instead it'd be irritating to have to maintain two attestation >> > policies. >> >> Why? >> >> If you have a mixed fleet then it's not too much asked to provide two >> data sets. On a TPM2 system you can enforce SHA-2 and only fallback to >> SHA-1 on TPM 1.2 hardware. No? > > No, beause having TPM2 hardware doesn't guarantee that your firmware > enables SHA-2 (which also means this is something that could change with > firmware updates, which means that refusing to support SHA-1 if the > SHA-2 banks are enabled could result in an entirely different policy > being required (and plausibly one that isn't implemented in their > existing tooling) It's not rocket science to have both variants supported in tooling, really. What a mess.