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Thu, 6 Feb 2020 13:49:35 +0000 (UTC) Received: from redhat.com (ovpn-112-65.ams2.redhat.com [10.36.112.65]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B7C8D790E5; Thu, 6 Feb 2020 13:49:21 +0000 (UTC) Date: Thu, 6 Feb 2020 13:49:18 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: [PATCH 02/13] qcrypto-luks: implement encryption key management Message-ID: <20200206134918.GM2391707@redhat.com> References: <20200130125319.GD1891831@redhat.com> <87zhe5ovbv.fsf@dusky.pond.sub.org> <20200130150108.GM1891831@redhat.com> <877e18oq76.fsf@dusky.pond.sub.org> <87mu9xxwzv.fsf@dusky.pond.sub.org> <20200205093011.GA5768@dhcp-200-226.str.redhat.com> <87tv45wdui.fsf@dusky.pond.sub.org> <20200205110250.GB5768@dhcp-200-226.str.redhat.com> <87blqdgl70.fsf@dusky.pond.sub.org> <87blqbu8xe.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87blqbu8xe.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.13.3 (2020-01-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: CAxFTFBaNSaEGmmSOU4WqA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , qemu-block@nongnu.org, qemu-devel@nongnu.org, Maxim Levitsky , Max Reitz , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Feb 06, 2020 at 02:44:45PM +0100, Markus Armbruster wrote: > Markus Armbruster writes: >=20 > > Kevin Wolf writes: > > > >> Am 05.02.2020 um 11:03 hat Markus Armbruster geschrieben: > >>> Kevin Wolf writes: > [...] > >>> > Adding a key gets more complicated with your proposed interface bec= ause > >>> > state must be set explicitly now whereas before it was derived > >>> > automatically from the fact that if you give a key, only active mak= es > >>> > sense. > >>>=20 > >>> The explicitness could be viewed as an improvement :) > >> > >> Not really. I mean, I really know to appreciate the advantages of > >> -blockdev where needed, but usually I don't want to type all that stuf= f > >> for the most common tasks. qemu-img amend is similar. > >> > >> For deleting, I might actually agree that explicitness is an > >> improvement, but for creating it's just unnecessary verbosity. > >> > >>> If you'd prefer implicit here: Max has patches for making union tags > >>> optional with a default. They'd let you default active to true. > >> > >> I guess this would improve the usability in this case. >=20 > Thinking and writing in the "Making QEMU easier for management tools and > applications" monster thread have made me realize we're mixing up two > aspects that ought to be kept separate: machine-friendly QMP and > human-friendly CLI. >=20 > You argue that >=20 > $ qemu-img amend -o encrypt.keys.0.new-secret=3Dsec0 test.qcow2 >=20 > is nicer than >=20 > $ qemu-img amend -o encrypt.keys.0.state=3Dactive,encrypt.keys.0.secr= et=3Dsec0 test.qcow2 >=20 > and you do have a point: humans want their CLI terse. Redundancy is > unwanted, except perhaps to protect users from dangerous accidents. In > this example, state=3Dactive is redundant when a secret is given, because > anything else would be an error. >=20 > In QMP, however, we like things simple and explicit, and we eschew > magic. >=20 > This particular magic might just be simple enough to be acceptable in > QMP. We'd "merely" have to support explicit defaults in the schema (a > clear improvement if you ask me), and optional union tags (tolerable as > long as the default comes from the schema, I guess). >=20 > My point is: QAPI schema design *must* focus on QMP and nothing else. > If we try to serve both QMP and human-friendly CLI, we'll likely botch > both. >=20 > I believe a truly human-friendly CLI requires more than just > human-friendly concrete syntax for QMP. Same as HMP, really. A human-friendly approach to this problem would never even have the generic "amend" design IMHO. Friendly would be to have a CLI that is approx the same as "cryptsetup" provides eg $ qemu-img add-key /path/to/disk enter key>.. re-enter key>... or qemu-img add-key --keyfile /some/file.txt /path/to/disk Regards, Daniel --=20 |: 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= :|