[Pulp-dev] signing service interface

[Brian Bouterse]

>From a goals perspective, we're trying to strengthen the interface between
Administrators configuring the signing service and plugin writers using
that signing service. One way to make that very explicit is to have the
contents of the public key live on the model itself (like we store keys on
Remote's as a TextField) for example.

Plugin writers using the signing interface could access it directly without
having to "sign dummy data". Additionally, you could even search
SigningService's by it which would be more usable when figuring out "oh
which one of these is the one I need to update". I don't see any downsides
to this proposal, but what do you think? What are the benefits of returning
the key at runtime from the Admin's script over this approach?

On Thu, May 7, 2020 at 3:51 AM Matthias Dellweg <mdellweg at redhat.com> wrote:

> > In case of the RPM plugin, the content handler needs to be able to know
> what the public key file is named without actually executing the sign() or
> validate() method.
> This opens a new can of worms. But as far as i see it, metadata is signed
> when creating the publication. Along with the signature, the signing script
> provides the public key as a file. The publication task now turns the
> signature into a published artifact, and imho could do the same to the key.
> Why does the content handler need to retrieve the key again? It is not
> supposed to change.
> Even if the content handler needed to decide on the fly, where to publish
> the key, then we could reference the artifact containing the key as a field
> on the publication and serve that.
>
> On Thu, May 7, 2020 at 2:34 AM Dennis Kliban <dkliban at redhat.com> wrote:
>
>> On Wed, May 6, 2020 at 4:07 AM Matthias Dellweg <mdellweg at redhat.com>
>> wrote:
>>
>>> As i see it, it is up to the subclass (e.g. AptReleaseSigningService,
>>> YumMetadataSigninigService, ...) to provide a stable interface. And the way
>>> it is implemented, the script for an AptReleaseSigninigService is required
>>> to report the filenames of both created signatures. And that is verified by
>>> the service before saving to the database.
>>>
>>
>> In case of the RPM plugin, the content handler needs to be able to know
>> what the public key file is named without actually executing the sign() or
>> validate() method. I don't see anything in the AptReleaseSigninigService[0]
>> that provides that functionality.
>>
>> The implementation of the AsciiArmoredDetachedSigningService[1] could
>> provide a method for retrieving the public key file name and the validate()
>> method would have to enforce it. Would this be more valuable to implement
>> at the base class (SigningService) level[2]?
>>
>> [0]
>> https://github.com/pulp/pulp_deb/blob/master/pulp_deb/app/models/signing_service.py#L12
>> [1]
>> https://github.com/pulp/pulpcore/blob/3.3/pulpcore/app/models/content.py#L447
>> [2]
>> https://github.com/pulp/pulpcore/blob/3.3/pulpcore/app/models/content.py#L377
>>
>>
>>>
>>> On Tue, May 5, 2020 at 11:51 PM Dennis Kliban <dkliban at redhat.com>
>>> wrote:
>>>
>>>> On Tue, May 5, 2020 at 3:39 AM Quirin Pamp <pamp at atix.de> wrote:
>>>>
>>>>> Could you explain the reasoning for a 'public.key' file?
>>>>>
>>>>
>>>> The public.key file is the file that a yum/dnf client can use to verify
>>>> that the metadata in an RPM repository was signed by the signing service
>>>> associated with the repository. The name of the file can be anything - the
>>>> path to it needs to be specified in the repository config on the client.
>>>>
>>>>
>>>>> In the case of the AptReleaseSigningService we built for pulp_deb we
>>>>> saw zero need for this file and consequently did not add it in.
>>>>>
>>>>> (It would not be hard to add it just to satisfy the interface, it just
>>>>> would not serve any useful purpose.)
>>>>>
>>>>
>>>> It is definitely up to each plugin if it wants to provide the public
>>>> key as part of the publication. It is currently impossible for the plugin
>>>> to know exactly what files are produced by the signing service. This is
>>>> where I would like to see an improvement in the API. Pupcore should provide
>>>> a guarantee to plugin writers that a signing service configured by an
>>>> administrator is functioning in a predictable way. One possible way to do
>>>> that is with an interface that lets a plugin writer inspect a signing
>>>> service without executing it. Though I am looking for other ideas in this
>>>> area.
>>>>
>>>>
>>>>>
>>>>> Since we are on the topic of signing services, a colleague has had a
>>>>> PR relating to them just sitting their waiting for a review for quite a
>>>>> while now ;-):
>>>>> https://github.com/pulp/pulpcore/pull/659
>>>>>
>>>>>
>>>>> It would be great if you (or somebody else) could have a look at it. I
>>>>> believe it is mostly ready, but probably needs the eyes of an experienced
>>>>> pulp core developer to look over it and suggest style consistency changes
>>>>> and where and whether to add documentation. ;-)
>>>>>
>>>>
>>>> I'll take a look at this PR.
>>>>
>>>>
>>>>
>>>>>
>>>>> Quirin
>>>>> ------------------------------
>>>>> *From:* pulp-dev-bounces at redhat.com <pulp-dev-bounces at redhat.com> on
>>>>> behalf of Dennis Kliban <dkliban at redhat.com>
>>>>> *Sent:* 04 May 2020 22:50:54
>>>>> *To:* Pulp-dev <pulp-dev at redhat.com>
>>>>> *Subject:* [Pulp-dev] signing service interface
>>>>>
>>>>> The Plugin API of Signing Services in Pulp 3 is too vague. I came to
>>>>> this conclusion while working with @lieter on an RPM plugin feature that
>>>>> allows users to download a repo config file from a distribution[0]. As a
>>>>> result, we decided to document that the signing service needs to produce a
>>>>> public key file named 'public.key'[1].
>>>>>
>>>>> We should revisit the design of the signing service API to ensure that
>>>>> we enforce this naming convention.
>>>>>
>>>>> [0] https://pulp.plan.io/issues/5356
>>>>> [1]
>>>>> https://github.com/pulp/pulp_rpm/pull/1687/files#diff-c91893c1f4e7afe73e414d1a76162463R30
>>>>>
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