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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 39D4CC3DA4B for ; Fri, 12 Jul 2024 13:40:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sSGUy-0001Gd-MS; Fri, 12 Jul 2024 09:39:44 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sSGUw-00017V-Ei for qemu-devel@nongnu.org; Fri, 12 Jul 2024 09:39:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sSGUt-0000SQ-75 for qemu-devel@nongnu.org; Fri, 12 Jul 2024 09:39:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1720791576; h=from:from:reply-to: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=Qhiafc0n/aHKsK3+/E4evBoBO1Ro70y/lQUVyFjpcws=; b=RJUFPvJS9JUacqWneUMm9nvAnU0ryJ24wBnFuCxTy2sfm2ZIp8VjueHgMt2fmF+P7N1yH4 N0iMTOqED0iZBcmLOhyroAn+k7vcezzD5SyKHBv7PAmY+D5oPkIUHQOOOf/hf70FZQogXe R0lS62TKgz8OmC4b8vYMsBScZsZr2Qc= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-64-Pf5zDevFO7ihs-HPMDdubw-1; Fri, 12 Jul 2024 09:39:34 -0400 X-MC-Unique: Pf5zDevFO7ihs-HPMDdubw-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8BA97196E08E; Fri, 12 Jul 2024 13:39:33 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.56]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 752953000181; Fri, 12 Jul 2024 13:39:29 +0000 (UTC) Date: Fri, 12 Jul 2024 14:39:26 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Hyman Huang Cc: qemu-devel@nongnu.org, Markus Armbruster , Kevin Wolf , Hanna Reitz , Eric Blake Subject: Re: [PATCH] docs/devel: Add introduction to LUKS volume with detached header Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.138, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Feb 20, 2024 at 12:04:42AM +0800, Hyman Huang wrote: > Signed-off-by: Hyman Huang > --- > MAINTAINERS | 1 + > docs/devel/luks-detached-header.rst | 182 ++++++++++++++++++++++++++++ > 2 files changed, 183 insertions(+) > create mode 100644 docs/devel/luks-detached-header.rst > > diff --git a/MAINTAINERS b/MAINTAINERS > index a24c2b51b6..e8b03032ab 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3422,6 +3422,7 @@ Detached LUKS header > M: Hyman Huang > S: Maintained > F: tests/qemu-iotests/tests/luks-detached-header > +F: docs/devel/luks-detached-header.rst > > D-Bus > M: Marc-André Lureau > diff --git a/docs/devel/luks-detached-header.rst b/docs/devel/luks-detached-header.rst > new file mode 100644 > index 0000000000..15e9ccde1d > --- /dev/null > +++ b/docs/devel/luks-detached-header.rst The new file neeeds adding to an index. We don't have anywhere for crypto yet, so I'm starting a crypto section thus: diff --git a/docs/devel/crypto.rst b/docs/devel/crypto.rst new file mode 100644 index 0000000000..39b1c910e7 --- /dev/null +++ b/docs/devel/crypto.rst @@ -0,0 +1,10 @@ +.. _crypto-ref: + +==================== +Cryptography in QEMU +==================== + +.. toctree:: + :maxdepth: 2 + + luks-detached-header diff --git a/docs/devel/index-internals.rst b/docs/devel/index-internals.rst index 5636e9cf1d..4ac7725d72 100644 --- a/docs/devel/index-internals.rst +++ b/docs/devel/index-internals.rst @@ -20,3 +20,4 @@ Details about QEMU's various subsystems including how to add features to them. vfio-iommufd writing-monitor-commands virtio-backends + crypto > @@ -0,0 +1,182 @@ > +================================ > +LUKS volume with detached header > +================================ > + > +Introduction > +============ > + > +This document gives an overview of the design of LUKS volume with detached > +header and how to use it. > + > +Background > +========== > + > +The LUKS format has ability to store the header in a separate volume from > +the payload. We could extend the LUKS driver in QEMU to support this use > +case. > + > +Normally a LUKS volume has a layout: > + > +:: > + > + +-----------------------------------------------+ > + | | | | > + disk | header | key material | disk payload data | > + | | | | > + +-----------------------------------------------+ > + > +With a detached LUKS header, you need 2 disks so getting: > + > +:: > + > + +--------------------------+ > + disk1 | header | key material | > + +--------------------------+ > + +---------------------+ > + disk2 | disk payload data | > + +---------------------+ > + > +There are a variety of benefits to doing this: > + > + * Secrecy - the disk2 cannot be identified as containing LUKS > + volume since there's no header > + * Control - if access to the disk1 is restricted, then even > + if someone has access to disk2 they can't unlock > + it. Might be useful if you have disks on NFS but > + want to restrict which host can launch a VM > + instance from it, by dynamically providing access > + to the header to a designated host > + * Flexibility - your application data volume may be a given > + size and it is inconvenient to resize it to > + add encryption.You can store the LUKS header > + separately and use the existing storage > + volume for payload > + * Recovery - corruption of a bit in the header may make the > + entire payload inaccessible. It might be > + convenient to take backups of the header. If > + your primary disk header becomes corrupt, you > + can unlock the data still by pointing to the > + backup detached header > + > +Architecture > +============ > + > +Take the qcow2 encryption, for example. The architecture of the > +LUKS volume with detached header is shown in the diagram below. > + > +There are two children of the root node: a file and a header. > +Data from the disk payload is stored in the file node. The > +LUKS header and key material are located in the header node, > +as previously mentioned. > + > +:: > + > + +-----------------------------+ > + Root node | foo[luks] | > + +-----------------------------+ > + | | > + file | header | > + | | > + +---------------------+ +------------------+ > + Child node |payload-format[qcow2]| |header-format[raw]| > + +---------------------+ +------------------+ > + | | > + file | file | > + | | > + +----------------------+ +---------------------+ > + Child node |payload-protocol[file]| |header-protocol[file]| > + +----------------------+ +---------------------+ > + | | > + | | > + | | > + Host storage Host storage > + > +Usage > +===== > + > +Create a LUKS disk with a detached header using qemu-img > +-------------------------------------------------------- > + > +Shell commandline:: > + > +# qemu-img create --object secret,id=sec0,data=abc123 -f luks \ > +> -o cipher-alg=aes-256,cipher-mode=xts -o key-secret=sec0 \ > +> -o detached-header=true test-header.img > +# qemu-img create -f qcow2 test-payload.qcow2 200G > +# qemu-img info 'json:{"driver":"luks","file":{"filename": \ > +> "test-payload.img"},"header":{"filename":"test-header.img"}}' This needs indentation by 2 spaces, and the ">" can be dropped. The same for all examples that follow. I'm going to make those changes and queue this patch, since they're trivial. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|