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=-13.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 40F20C07E96 for ; Thu, 8 Jul 2021 14:42:20 +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 A880361626 for ; Thu, 8 Jul 2021 14:42:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A880361626 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]:56624 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m1VEI-0004os-Ot for qemu-devel@archiver.kernel.org; Thu, 08 Jul 2021 10:42:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43076) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m1VDf-000440-6u for qemu-devel@nongnu.org; Thu, 08 Jul 2021 10:41:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:27876) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m1VDc-0004Rh-8z for qemu-devel@nongnu.org; Thu, 08 Jul 2021 10:41:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625755294; 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=YtHQ8cqJvQBzxl7tJfNkSbSIxO/2Ts67738xKvyKPw8=; b=YCv20pQKI1XuJyD1+gSemgg454M3iVw4/t/YgLkh/yvCs8iIyq7hCavEqyQMCz6+eH7qJ+ zoO4jPRw+jiLadTEaweLQOeqhQ3kvBn6dyOZFIU1WKGyegYudgT6MyUn46DZQl4cJ4+4Ul Ga4zlKcM7Z4yNjI4jUR5VC8tToJXDXw= 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-323-LhyjzF-OOfmI2D5zR_Y9Nw-1; Thu, 08 Jul 2021 10:41:32 -0400 X-MC-Unique: LhyjzF-OOfmI2D5zR_Y9Nw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 000DC102CB78 for ; Thu, 8 Jul 2021 14:41:31 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-104.ams2.redhat.com [10.36.112.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7F4791970F; Thu, 8 Jul 2021 14:41:29 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 169BB1132B52; Thu, 8 Jul 2021 16:41:28 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Subject: Re: [PATCH 11/18] crypto: rename des-rfb cipher to just des References: <20210706095924.764117-1-berrange@redhat.com> <20210706095924.764117-12-berrange@redhat.com> <87eecaffzg.fsf@dusky.pond.sub.org> Date: Thu, 08 Jul 2021 16:41:28 +0200 In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Wed, 7 Jul 2021 14:48:37 +0100") Message-ID: <87fswo50mf.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.45, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Eric Blake , qemu-devel@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 writes: > On Wed, Jul 07, 2021 at 02:47:15PM +0200, Markus Armbruster wrote: >> Daniel P. Berrang=C3=A9 writes: >>=20 >> > Currently the crypto layer exposes support for a 'des-rfb' >> > algorithm which is just normal single-DES, with the bits >> > in each key byte reversed. This special key munging is >> > required by the RFB protocol password authentication >> > mechanism. >> > >> > Since the crypto layer is generic shared code, it makes >> > more sense to do the key byte munging in the VNC server >> > code, and expose normal single-DES support. >> > >> > Signed-off-by: Daniel P. Berrang=C3=A9 >> > --- >>=20 >> [...] >>=20 >> > diff --git a/qapi/crypto.json b/qapi/crypto.json >> > index 7116ae9a46..6b3fadabac 100644 >> > --- a/qapi/crypto.json >> > +++ b/qapi/crypto.json >> > @@ -66,7 +66,7 @@ >> > # @aes-128: AES with 128 bit / 16 byte keys >> > # @aes-192: AES with 192 bit / 24 byte keys >> > # @aes-256: AES with 256 bit / 32 byte keys >> > -# @des-rfb: RFB specific variant of single DES. Do not use except in = VNC. >> > +# @des: DES with 56 bit / 8 byte keys. Do not use except in VNC. >> > # @3des: 3DES(EDE) with 192 bit / 24 byte keys (since 2.9) >> > # @cast5-128: Cast5 with 128 bit / 16 byte keys >> > # @serpent-128: Serpent with 128 bit / 16 byte keys >> > @@ -80,7 +80,7 @@ >> > { 'enum': 'QCryptoCipherAlgorithm', >> > 'prefix': 'QCRYPTO_CIPHER_ALG', >> > 'data': ['aes-128', 'aes-192', 'aes-256', >> > - 'des-rfb', '3des', >> > + 'des', '3des', >> > 'cast5-128', >> > 'serpent-128', 'serpent-192', 'serpent-256', >> > 'twofish-128', 'twofish-192', 'twofish-256']} >>=20 >> Is enum value "des-rfb" part of any external interface? > > Strictly speaking, yes, but in reality it doesn't matter. > > > The only place in QEMU that actually uses DES-RFB is the > VNC server code. That is an indirect usage when the user > sets the "password" option flag in QemuOpts. The fact that > it uses DES-RFB is an internal impl detail. > > The one place that does publically expose ability to set a > field using the QCryptoCipherAlgorithm enum type is the > LUKS support in the block layer: > > { 'struct': 'QCryptoBlockCreateOptionsLUKS', > 'base': 'QCryptoBlockOptionsLUKS', > 'data': { '*cipher-alg': 'QCryptoCipherAlgorithm', > '*cipher-mode': 'QCryptoCipherMode', > '*ivgen-alg': 'QCryptoIVGenAlgorithm', > '*ivgen-hash-alg': 'QCryptoHashAlgorithm', > '*hash-alg': 'QCryptoHashAlgorithm', > '*iter-time': 'int'}} > > eg exposed on CLI as: > > $ qemu-img create -f luks -o cipher-alg=3DNNN foo.luks 1G > > or equivalant with QMP blockdev-create > > While the QMP schema allows any valid QCryptoCipherAlgorithm > string to be set, the actual implementation does not. > > The crypto/block-luks.c code has a map between cipher algs > and LUKS format algoritm names: > > > static const QCryptoBlockLUKSCipherNameMap > qcrypto_block_luks_cipher_name_map[] =3D { > { "aes", qcrypto_block_luks_cipher_size_map_aes }, > { "cast5", qcrypto_block_luks_cipher_size_map_cast5 }, > { "serpent", qcrypto_block_luks_cipher_size_map_serpent }, > { "twofish", qcrypto_block_luks_cipher_size_map_twofish }, > }; > > If it isn't in that table, it can't be used. IOW, the only > scenario we're affecting in this rename is one which would > already result in an error condition > > Original behaviour: > > $ qemu-img create -f luks --object secret,id=3Dsec0,data=3D123 -o cipher= -alg=3Ddes-rfb,key-secret=3Dsec0 demo.luks 1G > Formatting 'demo.luks', fmt=3Dluks size=3D1073741824 key-secret=3Dsec0 ci= pher-alg=3Ddes-rfb > qemu-img: demo.luks: Algorithm 'des-rfb' not supported > > New behaviour: > > $ qemu-img create -f luks --object secret,id=3Dsec0,data=3D123 -o cipher-= alg=3Ddes-rfb,key-secret=3Dsec0 demo.luks 1G > Formatting 'demo.luks', fmt=3Dluks size=3D1073741824 key-secret=3Dsec0 ci= pher-alg=3Ddes-fish > qemu-img: demo.luks: Invalid parameter 'des-rfb' > > I considered this incompatibility to be acceptable, and thus > not worth going through a deprecation dance. Thanks for the explanation. I agree the deprecation dance is not necessary here. Please consider explaining this in your commit message. Suggest to append a variation of the tail of your explanation: Replacing cipher 'des-rfb' by 'des' looks like an incompatible interface change, but it doesn't matter. While the QMP schema allows ... qemu-img: demo.luks: Invalid parameter 'des-rfb' Also consider tweaking the title to crypto: Replace 'des-rfb' cipher by 'des' because it's not actually just a rename. Reviewed-by: Markus Armbruster