From patchwork Wed Jul 24 09:46:59 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= X-Patchwork-Id: 13740797 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 3AA1DC3DA61 for ; Wed, 24 Jul 2024 09:48:29 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sWYbS-0002ew-VF; Wed, 24 Jul 2024 05:48:11 -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 1sWYbR-0002X8-6f for qemu-devel@nongnu.org; Wed, 24 Jul 2024 05:48:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sWYbO-0003Or-VM for qemu-devel@nongnu.org; Wed, 24 Jul 2024 05:48:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721814485; 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=X3tnQlbYIo9RiEVK0g0LNnHZV6TRGTyfv8yD2i1HDZ0=; b=hBoLdAb5BX8nSe7TPyZZyOlEOny/3PhvEu5OFqNYxGhJI2Rp0O8jp+6pw8vTI3cDmwM5RS cTiDsN0Pg2AaNHU/FgOeYUmwz/N9RKF+GsMD6WlOSd/wK4SNV6o10q+IF95/nBfgck68hs kLSiaiKEsWGXdZ6JpAQWCADdfqenkio= Received: from mx-prod-mc-03.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-73-aA-5vbvgMtWiCxWGmpcuDQ-1; Wed, 24 Jul 2024 05:48:03 -0400 X-MC-Unique: aA-5vbvgMtWiCxWGmpcuDQ-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8C5981955D52; Wed, 24 Jul 2024 09:48:02 +0000 (UTC) Received: from toolbox.redhat.com (unknown [10.42.28.141]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4787D19560AA; Wed, 24 Jul 2024 09:47:54 +0000 (UTC) From: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Thomas Huth , Laurent Vivier , Markus Armbruster , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , =?utf-8?q?Phil?= =?utf-8?q?ippe_Mathieu-Daud=C3=A9?= , Eric Blake , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , Hyman Huang Subject: [PULL 04/11] docs/devel: Add introduction to LUKS volume with detached header Date: Wed, 24 Jul 2024 10:46:59 +0100 Message-ID: <20240724094706.30396-5-berrange@redhat.com> In-Reply-To: <20240724094706.30396-1-berrange@redhat.com> References: <20240724094706.30396-1-berrange@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Received-SPF: pass client-ip=170.10.129.124; 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=-0.133, 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_H3=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Hyman Huang Signed-off-by: Hyman Huang Signed-off-by: Daniel P. Berrangé --- MAINTAINERS | 1 + docs/devel/crypto.rst | 10 ++ docs/devel/index-internals.rst | 1 + docs/devel/luks-detached-header.rst | 182 ++++++++++++++++++++++++++++ 4 files changed, 194 insertions(+) create mode 100644 docs/devel/crypto.rst create mode 100644 docs/devel/luks-detached-header.rst diff --git a/MAINTAINERS b/MAINTAINERS index 73040829b1..98eddf7ae1 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3451,6 +3451,7 @@ 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/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 diff --git a/docs/devel/luks-detached-header.rst b/docs/devel/luks-detached-header.rst new file mode 100644 index 0000000000..94ec285c27 --- /dev/null +++ b/docs/devel/luks-detached-header.rst @@ -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"}}' + +Set up a VM's LUKS volume with a detached header +------------------------------------------------ + +Qemu commandline:: + + # qemu-system-x86_64 ... \ + -object '{"qom-type":"secret","id":"libvirt-3-format-secret", \ + "data":"abc123"}' \ + -blockdev '{"driver":"file","filename":"/path/to/test-header.img", \ + "node-name":"libvirt-1-storage"}' \ + -blockdev '{"node-name":"libvirt-1-format","read-only":false, \ + "driver":"raw","file":"libvirt-1-storage"}' \ + -blockdev '{"driver":"file","filename":"/path/to/test-payload.qcow2", \ + "node-name":"libvirt-2-storage"}' \ + -blockdev '{"node-name":"libvirt-2-format","read-only":false, \ + "driver":"qcow2","file":"libvirt-2-storage"}' \ + -blockdev '{"node-name":"libvirt-3-format","driver":"luks", \ + "file":"libvirt-2-format","header":"libvirt-1-format","key-secret": \ + "libvirt-3-format-secret"}' \ + -device '{"driver":"virtio-blk-pci","bus":XXX,"addr":YYY,"drive": \ + "libvirt-3-format","id":"virtio-disk1"}' + +Add LUKS volume to a VM with a detached header +---------------------------------------------- + +1. object-add the secret for decrypting the cipher stored in + LUKS header above:: + + # virsh qemu-monitor-command vm '{"execute":"object-add", \ + "arguments":{"qom-type":"secret", "id": \ + "libvirt-4-format-secret", "data":"abc123"}}' + +2. block-add the protocol node for LUKS header:: + + # virsh qemu-monitor-command vm '{"execute":"blockdev-add", \ + "arguments":{"node-name":"libvirt-1-storage", "driver":"file", \ + "filename": "/path/to/test-header.img" }}' + +3. block-add the raw-drived node for LUKS header:: + + # virsh qemu-monitor-command vm '{"execute":"blockdev-add", \ + "arguments":{"node-name":"libvirt-1-format", "driver":"raw", \ + "file":"libvirt-1-storage"}}' + +4. block-add the protocol node for disk payload image:: + + # virsh qemu-monitor-command vm '{"execute":"blockdev-add", \ + "arguments":{"node-name":"libvirt-2-storage", "driver":"file", \ + "filename":"/path/to/test-payload.qcow2"}}' + +5. block-add the qcow2-drived format node for disk payload data:: + + # virsh qemu-monitor-command vm '{"execute":"blockdev-add", \ + "arguments":{"node-name":"libvirt-2-format", "driver":"qcow2", \ + "file":"libvirt-2-storage"}}' + +6. block-add the luks-drived format node to link the qcow2 disk + with the LUKS header by specifying the field "header":: + + # virsh qemu-monitor-command vm '{"execute":"blockdev-add", \ + "arguments":{"node-name":"libvirt-3-format", "driver":"luks", \ + "file":"libvirt-2-format", "header":"libvirt-1-format", \ + "key-secret":"libvirt-2-format-secret"}}' + +7. hot-plug the virtio-blk device finally:: + + # virsh qemu-monitor-command vm '{"execute":"device_add", \ + "arguments": {"driver":"virtio-blk-pci", \ + "drive": "libvirt-3-format", "id":"virtio-disk2"}} + +TODO +==== + +1. Support the shared detached LUKS header within the VM.