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 11DB0C35254 for ; Mon, 17 Feb 2020 11:08:15 +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 CE7CD2070B for ; Mon, 17 Feb 2020 11:08:14 +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="J5tKyiaQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE7CD2070B 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]:43616 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j3eG6-0004X2-2N for qemu-devel@archiver.kernel.org; Mon, 17 Feb 2020 06:08:14 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36057) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j3eFO-00042J-Rk for qemu-devel@nongnu.org; Mon, 17 Feb 2020 06:07:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j3eFN-0000NI-E8 for qemu-devel@nongnu.org; Mon, 17 Feb 2020 06:07:30 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:41282 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 1j3eFN-0000Mn-9m for qemu-devel@nongnu.org; Mon, 17 Feb 2020 06:07:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581937648; 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=mOe8PalnRgQIHUfJjQPuDHUZq01LUC8mjQTKSuB+pQ4=; b=J5tKyiaQMazmARZCCWRWjrvww8p9SL4gjXksQhJ84bSaQVBMgIDFP0vX0gnWaZ/1dKhUp6 mjVEI8ipBrtPA31Ijy8t6tgM/6cGg4It1B/SWtsEjkTiajyWjlJVvfaF+83LtsgpvRWM/q fXLEylRMoW/rPphgAL9HME3wfOOoyTs= 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-186-lSfLezjhMfiU4piss_KeJQ-1; Mon, 17 Feb 2020 06:07:27 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F08B800D53; Mon, 17 Feb 2020 11:07:26 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 90EFB8681F; Mon, 17 Feb 2020 11:07:24 +0000 (UTC) Message-ID: Subject: Re: QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) From: Maxim Levitsky To: Kevin Wolf , Markus Armbruster Date: Mon, 17 Feb 2020 13:07:23 +0200 In-Reply-To: <20200217103700.GC6309@linux.fritz.box> References: <20200114193350.10830-1-mlevitsk@redhat.com> <20200114193350.10830-3-mlevitsk@redhat.com> <87lfp36gzh.fsf_-_@dusky.pond.sub.org> <20200217103700.GC6309@linux.fritz.box> Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: lSfLezjhMfiU4piss_KeJQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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: John Snow , "Daniel P. =?ISO-8859-1?Q?Berrang=E9?=" , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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. > > > > 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. > > > > I'm going to include a few design options. I'll mark them "Option:". > > > > The proposed "amend" interface takes a specification of desired state, > > and figures out how to get from here to there by itself. LUKS keyslots > > are one part of desired state. > > > > We commonly have eight LUKS keyslots. Each keyslot is either active or > > inactive. An active keyslot holds a secret. > > > > Goal: a QAPI type for specifying desired state of LUKS keyslots. > > > > Proposal: > > > > { 'enum': 'LUKSKeyslotState', > > 'data': [ 'active', 'inactive' ] } > > > > { 'struct': 'LUKSKeyslotActive', > > 'data': { 'secret': 'str', > > '*iter-time': 'int } } > > > > { 'struct': 'LUKSKeyslotInactive', > > 'data': { '*old-secret': 'str' } } > > > > { 'union': 'LUKSKeyslotAmend', > > 'base': { '*keyslot': 'int', > > 'state': 'LUKSKeyslotState' } > > 'discriminator': 'state', > > 'data': { 'active': 'LUKSKeyslotActive', > > 'inactive': 'LUKSKeyslotInactive' } } > > > > LUKSKeyslotAmend specifies desired state for a set of keyslots. > > 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 doing > everything at once would be safe). > > > Four cases: > > > > * @state is "active" > > > > Desired state is active holding the secret given by @secret. Optional > > @iter-time tweaks key stretching. > > > > The keyslot is chosen either by the user or by the system, as follows: > > > > - @keyslot absent > > > > One inactive keyslot chosen by the system. If none exists, error. > > > > - @keyslot present > > > > The keyslot given by @keyslot. > > > > If it's already active holding @secret, no-op. Rationale: the > > current state is the desired state. > > > > If it's already active holding another secret, error. Rationale: > > update in place is unsafe. > > > > Option: delete the "already active holding @secret" case. Feels > > inelegant to me. Okay if it makes things substantially simpler. > > > > * @state is "inactive" > > > > Desired state is inactive. > > > > Error if the current state has active keyslots, but the desired state > > has none. > > > > The user choses the keyslot by number and/or by the secret it holds, > > as follows: > > > > - @keyslot absent, @old-secret present > > > > All active keyslots holding @old-secret. If none exists, error. > > > > - @keyslot present, @old-secret absent > > > > The keyslot given by @keyslot. > > > > If it's already inactive, no-op. Rationale: the current state is > > the desired state. > > > > - both @keyslot and @old-secret present > > > > The keyslot given by keyslot. > > > > If it's inactive or holds a secret other than @old-secret, error. > > > > Option: error regardless of @old-secret, if that makes things > > simpler. > > > > - neither @keyslot not @old-secret present > > > > All keyslots. Note that this will error out due to "desired state > > has no active keyslots" unless the current state has none, either. > > > > Option: error out unconditionally. > > > > Note that LUKSKeyslotAmend can specify only one desired state for > > commonly just one keyslot. Rationale: this satisfies practical needs. > > 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. > > > > Examples: > > > > * Add a secret to some free keyslot: > > > > { "state": "active", "secret": "CIA/GRU/MI6" } > > > > * Deactivate all keyslots holding a secret: > > > > { "state": "inactive", "old-secret": "CIA/GRU/MI6" } > > > > * Add a secret to a specific keyslot: > > > > { "state": "active", "secret": "CIA/GRU/MI6", "keyslot": 0 } > > > > * Deactivate a specific keyslot: > > > > { "state": "inactive", "keyslot": 0 } > > > > Possibly less dangerous: > > > > { "state": "inactive", "keyslot": 0, "old-secret": "CIA/GRU/MI6" } > > > > Option: Make use of Max's patches to support optional union tag with > > default value to let us default @state to "active". I doubt this makes > > much of a difference in QMP. A human-friendly interface should probably > > be higher level anyway (Daniel pointed to cryptsetup). > > > > Option: LUKSKeyslotInactive member @old-secret could also be named > > @secret. I don't care. > > > > Option: delete @keyslot. It provides low-level slot access. > > Complicates the interface. Fine if we need lov-level slot access. Do > > we? > > > > I apologize for the time it has taken me to write this. > > > > Comments? > > Works for me (without taking any of the options). > > The unclear part is what the human-friendly interface should look like > and where it should live. I'm afraid doing only the QMP part and calling > the feature completed like we do so often won't work in this case. IMHO, I think that the best way to create human friendly part is to implement luks specific commands for qemu-img and use interface very similar to what cryptsetup does. Best regards, Maxim Levitsky > > Kevin