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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3EC78C433F5 for ; Fri, 11 Feb 2022 10:08:30 +0000 (UTC) Received: from localhost ([::1]:40534 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nISqq-0006Y8-WA for qemu-devel@archiver.kernel.org; Fri, 11 Feb 2022 05:08:29 -0500 Received: from eggs.gnu.org ([209.51.188.92]:40232) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nISpb-0005n0-8K for qemu-devel@nongnu.org; Fri, 11 Feb 2022 05:07:11 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:31278) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nISpX-0004h7-VG for qemu-devel@nongnu.org; Fri, 11 Feb 2022 05:07:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1644574027; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BOzr4KQp0OY4ksAld1eKLc0C9OZl3YpePIu89qBOMFU=; b=E28dyxXlOCc0T5KA5Rsa1kCxnWRNlGtZYHzkESTjUXXxMRR0v5vhY+cnSV7UiCJniJWMht nntzb48gSlUvL5kKCuX460s55TKlITbuYa6OXPJqmWYVjZ33aN78W0stvXLBGfJ14pUj/l qvPReF2y9MP4IT5hXJDiWCzesFXoZlQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-84-EeTcEn7bNrKHJy4DEwKlKA-1; Fri, 11 Feb 2022 05:07:04 -0500 X-MC-Unique: EeTcEn7bNrKHJy4DEwKlKA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DFA791091DB8; Fri, 11 Feb 2022 10:07:02 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.156]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4D7ED66E14; Fri, 11 Feb 2022 10:07:00 +0000 (UTC) Date: Fri, 11 Feb 2022 10:06:57 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Subject: Re: [PATCH] qapi, i386/sev: Add debug-launch-digest to launch-measure response Message-ID: References: <20220131111539.3091765-1-dovmurik@linux.ibm.com> <5f08d6d3-0279-50ed-5223-a9f3217e555d@linux.ibm.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Tom Lendacky , Ashish Kalra , Brijesh Singh , James Bottomley , Marcelo Tosatti , qemu-devel@nongnu.org, Markus Armbruster , Dov Murik , Tobin Feldman-Fitzthum , Paolo Bonzini , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Feb 10, 2022 at 07:39:01PM +0000, Dr. David Alan Gilbert wrote: > * Daniel P. Berrangé (berrange@redhat.com) wrote: > > I wonder if we're thinking of this at the wrong level though. Does > > it actually need to be QEMU providing this info to the guest owner ? > > > > Guest owners aren't going to be interacting with QEMU / QMP directly, > > nor are they likely to be interacting with libvirt directly. Their > > way into the public cloud will be via some high level API. eg the > > OpenStack Nova REST API, or the IBM Cloud API (whatever that may > > be). This high level mgmt infra is likely what is deciding which > > of the 'N' possible OVMF builds to pick for a given VM launch. It > > could easily just expose the full OVMF data to the user via its > > own API regardless of what query-sev does. > > > > Similarly if the cloud is choosing which kernel, out of N possible > > kernels to boot with, they could expose the raw kernel data somewhere > > in their API - we don't neccessarily need to expose that from QEMU. > > It gets more interesting where it's the guest which picks the > kernel/initrd; imagine the setup where the cloud reads the kernel/initrd > from the guest disk and passes that to qemu; one of the update ideas > would be just to let the guest update from a repo at it's own pace; > so the attestor doesn't know whether to expect a new or old kernel > from the guest; but it does know it should be one of the approved > set of kernels. So that scenario would effectively be the old Xen style pygrub where you have some script on the host to pull the kernel/initrd out of the guest /boot. On the plus side that would enable you to use a "normal" guest disk image with unencrypted /boot, instead of encrypting everything. The risk though is that you need a strong guarantee that the *only* data from /boot that is used is the kernel+initrd+cmdline that get included in the measurement. If the guest boot process reads anything else from /boot then your confidentiality is potentially doomed. This feels like quite a risky setup, as I don't know how you'd achieve the high level of confidence that stuff in /boot isn't going to cause danger to the guest during boot, or after boot. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|