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 F3001C3F2CD for ; Thu, 5 Mar 2020 12:17:54 +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 BF569208CD for ; Thu, 5 Mar 2020 12:17:54 +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="Xu9cRNOh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF569208CD 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]:47965 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j9pRp-0003q0-QK for qemu-devel@archiver.kernel.org; Thu, 05 Mar 2020 07:17:53 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36050) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j9pPt-0001uE-Hq for qemu-devel@nongnu.org; Thu, 05 Mar 2020 07:15:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j9pPq-0003ig-Mk for qemu-devel@nongnu.org; Thu, 05 Mar 2020 07:15:53 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:35397 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 1j9pPq-0003iO-HS for qemu-devel@nongnu.org; Thu, 05 Mar 2020 07:15:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583410549; 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=dTvHwz0BYCjpRYfidZ38RpDHxPcWsEJwvR6bc5RxKdE=; b=Xu9cRNOhnO/netifiiguq9fxUeJ6lOplj+5ZzASz4kl3/IpckdU3WOLWdMBNqsGxwiWJc0 TVkMHw0TU+Uybbiu/n0GprrvOahjwa96GaNkP0Ltw8wFcD7lXecCvPnMqeym8pVZBJfseW UHwyyJXqfJSguKhrjYInmo1YYSPrtps= 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-428-C-YU4YG0NgaG4cejqAZqAg-1; Thu, 05 Mar 2020 07:15:47 -0500 X-MC-Unique: C-YU4YG0NgaG4cejqAZqAg-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 7C050107ACC9; Thu, 5 Mar 2020 12:15:46 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id 865BF1CB; Thu, 5 Mar 2020 12:15:44 +0000 (UTC) Message-ID: <01d311ec104f7cc494875d3fb64c7d73657586ad.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: Markus Armbruster Date: Thu, 05 Mar 2020 14:15:43 +0200 In-Reply-To: <6e42d2ac5a761548ed3b4fdf7382441646839a9b.camel@redhat.com> References: <20200114193350.10830-1-mlevitsk@redhat.com> <20200114193350.10830-3-mlevitsk@redhat.com> <87lfp36gzh.fsf_-_@dusky.pond.sub.org> <6e42d2ac5a761548ed3b4fdf7382441646839a9b.camel@redhat.com> Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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: Kevin Wolf , Daniel =?ISO-8859-1?Q?P=2EBerrang=E9?= , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 2020-03-03 at 11:18 +0200, Maxim Levitsky wrote: > On Sat, 2020-02-15 at 15:51 +0100, Markus Armbruster wrote: > > 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. > > > > 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? > > I tried today to implement this but I hit a very unpleasant roadblock: > > Since QCrypto is generic (even though it only implements currently luks for raw/qcow2 usage, > and legacy qcow2 aes encryption), I still can't assume that this is always the case. > Thus I implemented the Qcrypto amend API in this way: > > ## > # @QCryptoBlockAmendOptions: > # > # The options that are available for all encryption formats > # when amending encryption settings > # > # Since: 5.0 > ## > { 'union': 'QCryptoBlockAmendOptions', > 'base': 'QCryptoBlockOptionsBase', > 'discriminator': 'format', > 'data': { > 'luks': 'QCryptoBlockAmendOptionsLUKS' } } > > However the QCryptoBlockAmendOptionsLUKS is a union too to be in line with the API proposal, > but that is not supported on QAPI level and after I and Markus talked about we are not sure > that it is worth it to implement this support only for this case. > > So far I see the following solutions > > > 1. Drop the QCryptoBlockAmendOptionsLUKS union for now. > This will bring the schema pretty much to be the same as my original proposal, > however the API will be the same thus once nested unions are implemented this union > can always be introduced again. > > 2. Drop the QCryptoBlockAmendOptions union. Strictly speaking this union is not needed > since it only has one member anyway, however this union is used both by qcow2 QAPI scheme, > so that it doesn't hardcode an encryption format for amend just like it doesn't for creation, > (this can be hardcoded for now as well for now as long as we don't have more amendable encryption formats). > However I also use the QCryptoBlockAmendOptions in C code in QCrypto API thus it will be ugly to use the > QCryptoBlockAmendOptionsLUKS instead. > > > 3. Make QCryptoBlockAmendOptionsLUKS a struct and add to it a nested member with new union type > (say QCryptoBlockAmendOptionsLUKS1) which will be exactly as QCryptoBlockAmendOptionsLUKS was. > > This IMHO is even uglier since it changes the API (which we can't later fix) and adds both a dummy struct > field and a dummy struct name. > > I personally vote 1. Any update? > > Best regards, > Maxim Levitsky > > >