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=-6.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 64488C4727E for ; Thu, 24 Sep 2020 16:16:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 09ADD2311B for ; Thu, 24 Sep 2020 16:16:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SZptJvB+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726868AbgIXQQd (ORCPT ); Thu, 24 Sep 2020 12:16:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:50154 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726697AbgIXQQd (ORCPT ); Thu, 24 Sep 2020 12:16:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600964191; 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: in-reply-to:in-reply-to:references:references; bh=8EfF16bCe0njopv3EGBmqLVMqnHunaWFKN8Yz67AbYg=; b=SZptJvB+pQlcd8YjUUqMlwenVsqSUxMuO+75CO6TJJPp2HagDGhNzOWU1FSlXs0AGN9WOg 0BDFZEPuLr8eEAs3qh0GKUaT5+Ad/wYr4my5antAmLTmrC4hDU/VQfDwv9F3DmFV4QMO3C WapHhgOXl4rQ9xypYuGnHQ2RmZF+8oU= 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-536-lKHT9NflMrW8m7cD-KYijw-1; Thu, 24 Sep 2020 12:16:29 -0400 X-MC-Unique: lKHT9NflMrW8m7cD-KYijw-1 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 0D521100746C; Thu, 24 Sep 2020 16:16:28 +0000 (UTC) Received: from localhost (unknown [10.18.25.174]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DA2C455785; Thu, 24 Sep 2020 16:16:24 +0000 (UTC) Date: Thu, 24 Sep 2020 12:16:24 -0400 From: Mike Snitzer To: Eric Biggers Cc: Satya Tangirala , Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, Alasdair Kergon Subject: Re: [PATCH 2/3] dm: add support for passing through inline crypto support Message-ID: <20200924161624.GC14369@redhat.com> References: <20200909234422.76194-1-satyat@google.com> <20200909234422.76194-3-satyat@google.com> <20200922003255.GC32959@sol.localdomain> <20200924011438.GD10500@redhat.com> <20200924071721.GA1883346@google.com> <20200924134649.GB13849@redhat.com> <20200924154550.GA1266@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200924154550.GA1266@sol.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Sep 24 2020 at 11:45am -0400, Eric Biggers wrote: > On Thu, Sep 24, 2020 at 09:46:49AM -0400, Mike Snitzer wrote: > > > > Can you help me better understand the expected consumer of this code? > > > > If you have something _real_ please be explicit. It makes justifying > > > > supporting niche code like this more tolerable. > > > > > > So the motivation for this code was that Android currently uses a device > > > mapper target on top of a phone's disk for user data. On many phones, > > > that disk has inline encryption support, and it'd be great to be able to > > > make use of that. The DM device configuration isn't changed at runtime. > > > > OK, which device mapper target is used? > > There are several device-mapper targets that Android can require for the > "userdata" partition -- potentially in a stack of more than one: > > dm-linear: required for Dynamic System Updates > (https://developer.android.com/topic/dsu) > > dm-bow: required for User Data Checkpoints on ext4 > (https://source.android.com/devices/tech/ota/user-data-checkpoint) > (https://patchwork.kernel.org/patch/10838743/) > > dm-default-key: required for metadata encryption > (https://source.android.com/security/encryption/metadata) Please work with all google stakeholders to post the latest code for the dm-bow and dm-default-key targets and I'll work through them. I think the more code we have to inform DM core's implementation the better off we'll be in the long run. Could also help improve these targets as a side-effect of additional review. I know I largely ignored dm-bow before but that was more to do with competing tasks, etc. I'll try my best... > We're already carrying this patchset in the Android common kernels since late > last year, as it's required for inline encryption to work when any of the above > is used. So this is something that is needed and is already being used. > > Now, you don't have to "count" dm-bow and dm-default-key since they aren't > upstream; that leaves dm-linear. But hopefully the others at least show that > architecturally, dm-linear is just the initial use case, and this patchset also > makes it easy to pass through inline crypto on any other target that can support > it (basically, anything that doesn't change the data itself as it goes through). Sure, that context really helps. About "basically, anything that doesn't change the data itself as it goes through": could you be a bit more precise? Very few DM targets actually change the data as associated bios are remapped. I'm just wondering if your definition of "doesn't change the data" includes things more subtle than the data itself? Thanks, Mike