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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64E60C4360F for ; Wed, 3 Apr 2019 22:27:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23F8A2147C for ; Wed, 3 Apr 2019 22:27:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Hn5DMg+q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbfDCW1Z (ORCPT ); Wed, 3 Apr 2019 18:27:25 -0400 Received: from mail-io1-f67.google.com ([209.85.166.67]:45389 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726167AbfDCW1Z (ORCPT ); Wed, 3 Apr 2019 18:27:25 -0400 Received: by mail-io1-f67.google.com with SMTP id s7so257662iom.12 for ; Wed, 03 Apr 2019 15:27:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+3faNpmag6jYME5yNI69COYIz0d4qS337f0eaty0yLY=; b=Hn5DMg+qfhg8lnUXmQEgJ4eyGQRy86cBCVdOiz+SoR4bX8ULjx3usvppAd3U/Tjo+3 pHcQLhA3s2MAgrAxsJP7GSq7JG6jMjmn4mjKyBEp/bGnUhoOwSeCwPTclx6LWkhYulrq SoU9wFkqFC1RrPQXHhojDrXTjLSQN+So9U3wt214BoVJ5XUbH4bQp44HLENcmeD4Mb3X qdL0djpsWoB7JX+T5M6PCzE9BbFqDSBCTtApX3wdEYLcOQPrAI6bORTgR2IpA6jHh8MT x6QCOhB3xdwb3cRgS2IhQ6tWhcf8Fn7ZIVFwQJWsgDGNEbeTqB6zPq7VypFgzQgg3Ss5 o+pA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+3faNpmag6jYME5yNI69COYIz0d4qS337f0eaty0yLY=; b=beOEZv02MP05JXQv2eYui7s5Uz9wKHiqLtTCLQXehVnWO11YYAEEnpyJwZNJQBBuGo 2jM3fifUn6Iox7N2ljfBAHBYSHZyT3FZQYheyNXyfjAqrFYujTkn9ERgNbDAFevXdD1l wgezVWTzfQga525JIc+lnYHfYL9zjthhCPj6muRioyQzy89ik/dUrniW08Q9O3SuHRqN czPwyUb+L0eyu6JOF1gnfK1ClmyUpA8OIHUT3G4+kDMkmyW65Ks84j+yil7RJeORSBEn W1CMzkgTods3vdBjmmiIidpYk1UchoQVc3Jm6JVdnhkC4MYc6opihB1Nr440uAvoiadb WxTQ== X-Gm-Message-State: APjAAAVF0ACCOqiLkzFuw8zVToEr0g7tNCmJC9pns6dEIlthh3a1gtBj IQRe6Z+HDsgepFwoIe9kn2ZlG3pvXxauYInqvD2orA== X-Google-Smtp-Source: APXvYqyjaucmj870Vz9jHZPatpcn5T0LihCycvdCx7VILq9npP5A6ssDHW9qOcaFARXAimNtxuuxG36+qUImTOEY86c= X-Received: by 2002:a5e:d514:: with SMTP id e20mr2067567iom.8.1554330444296; Wed, 03 Apr 2019 15:27:24 -0700 (PDT) MIME-Version: 1.0 References: <20190402181505.25037-1-cclaudio@linux.ibm.com> <4ce5e057-0702-b0d5-7bb2-cea5b22e2efa@linux.ibm.com> <2208f156-d441-3082-2f4c-8030c84ef788@linux.ibm.com> In-Reply-To: <2208f156-d441-3082-2f4c-8030c84ef788@linux.ibm.com> From: Matthew Garrett Date: Wed, 3 Apr 2019 15:27:13 -0700 Message-ID: Subject: Re: [PATCH 0/4] Enabling secure boot on PowerNV systems To: Claudio Carvalho Cc: linuxppc-dev@ozlabs.org, linux-efi , linux-integrity , Linux Kernel Mailing List , Michael Ellerman , Paul Mackerras , Benjamin Herrenschmidt , Ard Biesheuvel , Jeremy Kerr , Matthew Garret , Nayna Jain Content-Type: text/plain; charset="UTF-8" Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Tue, Apr 2, 2019 at 4:31 PM Claudio Carvalho wrote: > > > On 4/2/19 6:51 PM, Matthew Garrett wrote: > > So you implement the full PK/KEK/db/dbx/dbt infrastructure, and > > updates are signed in the same way? > > For the first version, our firmware will implement a simplistic PK, KEK and > db infrastructure (without dbx and dbt) where only the Setup and User modes > will be supported. Not supporting dbx seems like a pretty significant shortcoming. How are signatures meant to be revoked? > PK, KEK and db updates will be signed the same way, that is, using > userspace tooling like efitools in PowerNV. As for the authentication > descriptors, only the EFI_VARIABLE_AUTHENTICATION_2 descriptor will be > supported. Is this API documented? > > In that case we might be better off with a generic interface for this > > purpose that we can expose on all platforms that implement a secure > > boot key hierarchy. Having an efivarfs that doesn't allow the creation > > of arbitrary attributes may break other existing userland > > expectations. > > > For what it's worth, gsmi uses the efivars infrastructure for EFI-like > variables. My recollection is that at the time the Chromebook firmware still had EFI underpinnings and the gsmi code was largely just an alternate mechanism for calling into something that was fundamentally the EFI variable store. With hindsight I don't think layering this was the right move - we've adjusted the semantics of efivarfs on more than one occasion to deal with the behaviour of real-world EFI platforms, and I don't think it's helpful to end up in a situation where we're trying to keep behaviour consistent among entirely different firmware interfaces. > What might a generic interface look like? It would have to work for > existing secure boot solutions - including EFI - which would seem to imply > changes to userspace tools. I think that depends on exactly what problem you're trying to solve. Some aspects of the EFI secure boot design end up mirroring the economics of the PC ecosystem rather than being inherently good design goals, so it'd be helpful to know whether you're taking this solution because you want the same three-level key infrastructure or because that just leaves you compatible with the tooling.