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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 61AC3C11D2F for ; Mon, 24 Feb 2020 14:51:22 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 208DD20714 for ; Mon, 24 Feb 2020 14:51:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IKfXCk+e" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 208DD20714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37710 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6F4r-0006ox-Bw for qemu-devel@archiver.kernel.org; Mon, 24 Feb 2020 09:51:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:53827) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6F40-0006En-3Z for qemu-devel@nongnu.org; Mon, 24 Feb 2020 09:50:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6F3y-0001to-GF for qemu-devel@nongnu.org; Mon, 24 Feb 2020 09:50:28 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:56364 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j6F3y-0001sM-AK for qemu-devel@nongnu.org; Mon, 24 Feb 2020 09:50:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582555825; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1cq+l5x2Q4Y0VCMhvboK4Y97PT0P98v/1MVzByss3x8=; b=IKfXCk+eWeNlbSXHS/SaSEkDGCzxHZwpVpt1YmZsF68SKrUzM+svMIpwd63Th+Vr8255Ry 3TxGoshVnoqwMUBHM0RINckwi+/L3IxJCF+BTfzeB/7EN+i7kKHtgMVdSikTLFqppEJFPm Y9ICUQEPr3AutgfIPWszy5uLc9Zqy6s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-185-6GT6cxA_Pb2WRPYkfRZIhA-1; Mon, 24 Feb 2020 09:50:22 -0500 X-MC-Unique: 6GT6cxA_Pb2WRPYkfRZIhA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3C675802563; Mon, 24 Feb 2020 14:50:20 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6A98F5D9E5; Mon, 24 Feb 2020 14:50:18 +0000 (UTC) Message-ID: <0bc646700ef5cfc6a58e2c4efa107fab3817b7f7.camel@redhat.com> Subject: Re: QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) From: Maxim Levitsky To: "Daniel P." =?ISO-8859-1?Q?Berrang=E9?= Date: Mon, 24 Feb 2020 16:50:17 +0200 In-Reply-To: <20200224144621.GT635661@redhat.com> References: <20200114193350.10830-1-mlevitsk@redhat.com> <20200114193350.10830-3-mlevitsk@redhat.com> <87lfp36gzh.fsf_-_@dusky.pond.sub.org> <20200217103700.GC6309@linux.fritz.box> <20200224144621.GT635661@redhat.com> Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-block@nongnu.org, qemu-devel@nongnu.org, Markus Armbruster , Max Reitz , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 2020-02-24 at 14:46 +0000, Daniel P. Berrang=C3=A9 wrote: > On Mon, Feb 17, 2020 at 01:07:23PM +0200, Maxim Levitsky wrote: > > On Mon, 2020-02-17 at 11:37 +0100, Kevin Wolf wrote: > > > Am 15.02.2020 um 15:51 hat Markus Armbruster geschrieben: > > > > Review of this patch led to a lengthy QAPI schema design discussion= . > > > > Let me try to condense it into a concrete proposal. > > > >=20 > > > > This is about the QAPI schema, and therefore about QMP. The > > > > human-friendly interface is out of scope. Not because it's not > > > > important (it clearly is!), only because we need to *focus* to have= a > > > > chance at success. > > > >=20 > > > > I'm going to include a few design options. I'll mark them "Option:= ". > > > >=20 > > > > The proposed "amend" interface takes a specification of desired sta= te, > > > > and figures out how to get from here to there by itself. LUKS keys= lots > > > > are one part of desired state. > > > >=20 > > > > We commonly have eight LUKS keyslots. Each keyslot is either activ= e or > > > > inactive. An active keyslot holds a secret. > > > >=20 > > > > Goal: a QAPI type for specifying desired state of LUKS keyslots. > > > >=20 > > > > Proposal: > > > >=20 > > > > { 'enum': 'LUKSKeyslotState', > > > > 'data': [ 'active', 'inactive' ] } > > > >=20 > > > > { 'struct': 'LUKSKeyslotActive', > > > > 'data': { 'secret': 'str', > > > > '*iter-time': 'int } } > > > >=20 > > > > { 'struct': 'LUKSKeyslotInactive', > > > > 'data': { '*old-secret': 'str' } } > > > >=20 > > > > { 'union': 'LUKSKeyslotAmend', > > > > 'base': { '*keyslot': 'int', > > > > 'state': 'LUKSKeyslotState' } > > > > 'discriminator': 'state', > > > > 'data': { 'active': 'LUKSKeyslotActive', > > > > 'inactive': 'LUKSKeyslotInactive' } } > > > >=20 > > > > LUKSKeyslotAmend specifies desired state for a set of keyslots. > > >=20 > > > Though not arbitrary sets of keyslots, it's only a single keyslot or > > > multiple keyslots containing the same secret. Might be good enough in > > > practice, though it means that you may have to issue multiple amend > > > commands to get to the final state that you really want (even if doin= g > > > everything at once would be safe). > > >=20 > > > > Four cases: > > > >=20 > > > > * @state is "active" > > > >=20 > > > > Desired state is active holding the secret given by @secret. Opt= ional > > > > @iter-time tweaks key stretching. > > > >=20 > > > > The keyslot is chosen either by the user or by the system, as fol= lows: > > > >=20 > > > > - @keyslot absent > > > >=20 > > > > One inactive keyslot chosen by the system. If none exists, err= or. > > > >=20 > > > > - @keyslot present > > > >=20 > > > > The keyslot given by @keyslot. > > > >=20 > > > > If it's already active holding @secret, no-op. Rationale: the > > > > current state is the desired state. > > > >=20 > > > > If it's already active holding another secret, error. Rational= e: > > > > update in place is unsafe. > > > >=20 > > > > Option: delete the "already active holding @secret" case. Feel= s > > > > inelegant to me. Okay if it makes things substantially simpler= . > > > >=20 > > > > * @state is "inactive" > > > >=20 > > > > Desired state is inactive. > > > >=20 > > > > Error if the current state has active keyslots, but the desired s= tate > > > > has none. > > > >=20 > > > > The user choses the keyslot by number and/or by the secret it hol= ds, > > > > as follows: > > > >=20 > > > > - @keyslot absent, @old-secret present > > > >=20 > > > > All active keyslots holding @old-secret. If none exists, error= . > > > >=20 > > > > - @keyslot present, @old-secret absent > > > >=20 > > > > The keyslot given by @keyslot. > > > >=20 > > > > If it's already inactive, no-op. Rationale: the current state = is > > > > the desired state. > > > >=20 > > > > - both @keyslot and @old-secret present > > > >=20 > > > > The keyslot given by keyslot. > > > >=20 > > > > If it's inactive or holds a secret other than @old-secret, erro= r. > > > >=20 > > > > Option: error regardless of @old-secret, if that makes things > > > > simpler. > > > >=20 > > > > - neither @keyslot not @old-secret present > > > >=20 > > > > All keyslots. Note that this will error out due to "desired st= ate > > > > has no active keyslots" unless the current state has none, eith= er. > > > >=20 > > > > Option: error out unconditionally. > > > >=20 > > > > Note that LUKSKeyslotAmend can specify only one desired state for > > > > commonly just one keyslot. Rationale: this satisfies practical nee= ds. > > > > An array of LUKSKeyslotAmend could specify desired state for all > > > > keyslots. However, multiple array elements could then apply to the= same > > > > slot. We'd have to specify how to resolve such conflicts, and we'd= have > > > > to code up conflict detection. Not worth it. > > > >=20 > > > > Examples: > > > >=20 > > > > * Add a secret to some free keyslot: > > > >=20 > > > > { "state": "active", "secret": "CIA/GRU/MI6" } > > > >=20 > > > > * Deactivate all keyslots holding a secret: > > > >=20 > > > > { "state": "inactive", "old-secret": "CIA/GRU/MI6" } > > > >=20 > > > > * Add a secret to a specific keyslot: > > > >=20 > > > > { "state": "active", "secret": "CIA/GRU/MI6", "keyslot": 0 } > > > >=20 > > > > * Deactivate a specific keyslot: > > > >=20 > > > > { "state": "inactive", "keyslot": 0 } > > > >=20 > > > > Possibly less dangerous: > > > >=20 > > > > { "state": "inactive", "keyslot": 0, "old-secret": "CIA/GRU/MI6" = } > > > >=20 > > > > Option: Make use of Max's patches to support optional union tag wit= h > > > > default value to let us default @state to "active". I doubt this m= akes > > > > much of a difference in QMP. A human-friendly interface should pro= bably > > > > be higher level anyway (Daniel pointed to cryptsetup). > > > >=20 > > > > Option: LUKSKeyslotInactive member @old-secret could also be named > > > > @secret. I don't care. > > > >=20 > > > > Option: delete @keyslot. It provides low-level slot access. > > > > Complicates the interface. Fine if we need lov-level slot access. = Do > > > > we? > > > >=20 > > > > I apologize for the time it has taken me to write this. > > > >=20 > > > > Comments? > > >=20 > > > Works for me (without taking any of the options). > > >=20 > > > The unclear part is what the human-friendly interface should look lik= e > > > and where it should live. I'm afraid doing only the QMP part and call= ing > > > the feature completed like we do so often won't work in this case. > >=20 > > IMHO, I think that the best way to create human friendly part is to imp= lement > > luks specific commands for qemu-img and use interface very similar > > to what cryptsetup does. >=20 > I think we can have a generic 'qemu-img amend' for machine type, with the > complex dotted syntax. >=20 > And then have two human friendly commands 'qemu-img crypt-add-key' and > 'qemu-img crypt-del-key' similarish to cryptsetup. Yep, this is exactly what I was thinking about this as well! Best regards, =09Maxim Levitsky >=20 > Regards, > Daniel