From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, qemu-devel@nongnu.org,
Markus Armbruster <armbru@redhat.com>,
Max Reitz <mreitz@redhat.com>, John Snow <jsnow@redhat.com>
Subject: Re: QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management)
Date: Mon, 24 Feb 2020 14:46:21 +0000 [thread overview]
Message-ID: <20200224144621.GT635661@redhat.com> (raw)
In-Reply-To: <fd30b30b11772bd59ccf4573a35fc01d5bd51379.camel@redhat.com>
On Mon, Feb 17, 2020 at 01:07:23PM +0200, Maxim Levitsky wrote:
> On Mon, 2020-02-17 at 11:37 +0100, Kevin Wolf wrote:
> > Am 15.02.2020 um 15:51 hat Markus Armbruster geschrieben:
> > > 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.
> >
> > Though not arbitrary sets of keyslots, it's only a single keyslot or
> > multiple keyslots containing the same secret. Might be good enough in
> > practice, though it means that you may have to issue multiple amend
> > commands to get to the final state that you really want (even if doing
> > everything at once would be safe).
> >
> > > 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?
> >
> > Works for me (without taking any of the options).
> >
> > The unclear part is what the human-friendly interface should look like
> > and where it should live. I'm afraid doing only the QMP part and calling
> > the feature completed like we do so often won't work in this case.
>
> IMHO, I think that the best way to create human friendly part is to implement
> luks specific commands for qemu-img and use interface very similar
> to what cryptsetup does.
I think we can have a generic 'qemu-img amend' for machine type, with the
complex dotted syntax.
And then have two human friendly commands 'qemu-img crypt-add-key' and
'qemu-img crypt-del-key' similarish to cryptsetup.
Regards,
Daniel
--
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next prev parent reply other threads:[~2020-02-24 14:47 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 19:33 [PATCH 00/13] LUKS: encryption slot management using amend interface Maxim Levitsky
2020-01-14 19:33 ` [PATCH 01/13] qcrypto: add generic infrastructure for crypto options amendment Maxim Levitsky
2020-01-28 16:59 ` Daniel P. Berrangé
2020-01-29 17:49 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 02/13] qcrypto-luks: implement encryption key management Maxim Levitsky
2020-01-21 7:54 ` Markus Armbruster
2020-01-21 13:13 ` Maxim Levitsky
2020-01-28 17:11 ` Daniel P. Berrangé
2020-01-28 17:32 ` Daniel P. Berrangé
2020-01-29 17:54 ` Maxim Levitsky
2020-01-30 12:38 ` Kevin Wolf
2020-01-30 12:53 ` Daniel P. Berrangé
2020-01-30 14:23 ` Kevin Wolf
2020-01-30 14:30 ` Daniel P. Berrangé
2020-01-30 14:53 ` Markus Armbruster
2020-01-30 14:47 ` Markus Armbruster
2020-01-30 15:01 ` Daniel P. Berrangé
2020-01-30 16:37 ` Markus Armbruster
2020-02-05 8:24 ` Markus Armbruster
2020-02-05 9:30 ` Kevin Wolf
2020-02-05 10:03 ` Markus Armbruster
2020-02-05 11:02 ` Kevin Wolf
2020-02-05 14:31 ` Markus Armbruster
2020-02-06 13:44 ` Markus Armbruster
2020-02-06 13:49 ` Daniel P. Berrangé
2020-02-06 14:20 ` Max Reitz
2020-02-05 10:23 ` Daniel P. Berrangé
2020-02-05 14:31 ` Markus Armbruster
2020-02-06 13:20 ` Markus Armbruster
2020-02-06 13:36 ` Daniel P. Berrangé
2020-02-06 14:25 ` Kevin Wolf
2020-02-06 15:19 ` Markus Armbruster
2020-02-06 15:23 ` Maxim Levitsky
2020-01-30 15:45 ` Maxim Levitsky
2020-01-28 17:21 ` Daniel P. Berrangé
2020-01-30 12:58 ` Maxim Levitsky
2020-02-15 14:51 ` QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) Markus Armbruster
2020-02-16 8:05 ` Maxim Levitsky
2020-02-17 6:45 ` QAPI schema for desired state of LUKS keyslots Markus Armbruster
2020-02-17 8:19 ` Maxim Levitsky
2020-02-17 10:37 ` QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) Kevin Wolf
2020-02-17 11:07 ` Maxim Levitsky
2020-02-24 14:46 ` Daniel P. Berrangé [this message]
2020-02-24 14:50 ` Maxim Levitsky
2020-02-17 12:28 ` QAPI schema for desired state of LUKS keyslots Markus Armbruster
2020-02-17 12:44 ` Eric Blake
2020-02-24 14:43 ` Daniel P. Berrangé
2020-02-24 14:45 ` QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) Daniel P. Berrangé
2020-02-25 12:15 ` Max Reitz
2020-02-25 16:48 ` QAPI schema for desired state of LUKS keyslots Markus Armbruster
2020-02-25 17:00 ` Max Reitz
2020-02-26 7:28 ` Markus Armbruster
2020-02-26 9:18 ` Maxim Levitsky
2020-02-25 17:18 ` Daniel P. Berrangé
2020-03-03 9:18 ` QAPI schema for desired state of LUKS keyslots (was: [PATCH 02/13] qcrypto-luks: implement encryption key management) Maxim Levitsky
2020-03-05 12:15 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 03/13] block: amend: add 'force' option Maxim Levitsky
2020-01-14 19:33 ` [PATCH 04/13] block: amend: separate amend and create options for qemu-img Maxim Levitsky
2020-01-28 17:23 ` Daniel P. Berrangé
2020-01-30 15:54 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 05/13] block/crypto: rename two functions Maxim Levitsky
2020-01-14 19:33 ` [PATCH 06/13] block/crypto: implement the encryption key management Maxim Levitsky
2020-01-28 17:27 ` Daniel P. Berrangé
2020-01-30 16:08 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 07/13] qcow2: extend qemu-img amend interface with crypto options Maxim Levitsky
2020-01-28 17:30 ` Daniel P. Berrangé
2020-01-30 16:09 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 08/13] iotests: filter few more luks specific create options Maxim Levitsky
2020-01-28 17:36 ` Daniel P. Berrangé
2020-01-30 16:12 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 09/13] qemu-iotests: qemu-img tests for luks key management Maxim Levitsky
2020-01-14 19:33 ` [PATCH 10/13] block: add generic infrastructure for x-blockdev-amend qmp command Maxim Levitsky
2020-01-21 7:59 ` Markus Armbruster
2020-01-21 13:58 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 11/13] block/crypto: implement blockdev-amend Maxim Levitsky
2020-01-28 17:40 ` Daniel P. Berrangé
2020-01-30 16:24 ` Maxim Levitsky
2020-01-14 19:33 ` [PATCH 12/13] block/qcow2: " Maxim Levitsky
2020-01-28 17:41 ` Daniel P. Berrangé
2020-01-14 19:33 ` [PATCH 13/13] iotests: add tests for blockdev-amend Maxim Levitsky
2020-01-14 21:16 ` [PATCH 00/13] LUKS: encryption slot management using amend interface no-reply
2020-01-16 14:01 ` Maxim Levitsky
2020-01-14 21:17 ` no-reply
2020-01-16 14:19 ` Maxim Levitsky
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