[openstack-dev] [Neutron][LBaaS] TLS capability - SNI - Extracting SubjectCommonName and/or SubjectAlternativeNames from X509

Stephen Balukoff sbalukoff at bluebox.net
Thu Jul 17 15:19:30 UTC 2014


Ok, folks!

Per the IRC meeting this morning, we came to the following consensus
regarding how TLS certificates are handled, how SAN is handled, and how
hostname conflict resolution is handled. I will be responding to all three
of the currently ongoing mailing list discussions with this info:


   - Driver does not have to use SAN that is passed from API layer, but SAN
   will be available to drivers at the API layer. This will be mentioned
   explicitly in the spec.
   - Order is a mandatory attribute. It's intended to be used as a "hint"
   for hostname conflict resolution, but it's ultimately up to the driver to
   decide how to resolve the conflict. (In other words, although it is a
   mandatory attribute in our model, drivers are free to ignore it.)
   - Drivers are allowed to vary their behavior when choosing how to
   implement hostname conflict resolution since there is no single algorithm
   here that all vendors are able to support. (This is anticipated to be a
   rare edge case anyway.)

I think Evgeny will be updating the specs to reflect this decision so that
it is documented--  we hope to get ultimate approval of the spec in the
next day or two.

Thanks,
Stephen




On Wed, Jul 16, 2014 at 7:31 PM, Stephen Balukoff <sbalukoff at bluebox.net>
wrote:

> Just saw this thread after responding to the other:
>
> I'm in favor of Evgeny's proposal. It sounds like it should resolve most
> (if not all) of the operators', vendors' and users' concerns with regard to
> handling TLS certificates.
>
> Stephen
>
>
> On Wed, Jul 16, 2014 at 12:35 PM, Carlos Garza <carlos.garza at rackspace.com
> > wrote:
>
>>
>> On Jul 16, 2014, at 10:55 AM, Vijay Venkatachalam <
>> Vijay.Venkatachalam at citrix.com>
>>  wrote:
>>
>> > Apologies for the delayed response.
>> >
>> > I am OK with displaying the certificates contents as part of the API,
>> that should not harm.
>> >
>> > I think the discussion has to be split into 2 topics.
>> >
>> > 1.       Certificate conflict resolution. Meaning what is expected when
>> 2 or more certificates become eligible during SSL negotiation
>> > 2.       SAN support
>> >
>>
>>     Ok cool that makes more sense. #2 seems to be met by Evgeny proposal.
>> I'll let you folks decide the conflict resolution issue #1.
>>
>>
>> > I will send out 2 separate mails on this.
>> >
>> >
>> > From: Samuel Bercovici [mailto:SamuelB at Radware.com]
>> > Sent: Tuesday, July 15, 2014 11:52 PM
>> > To: OpenStack Development Mailing List (not for usage questions); Vijay
>> Venkatachalam
>> > Subject: RE: [openstack-dev] [Neutron][LBaaS] TLS capability - SNI -
>> Extracting SubjectCommonName and/or SubjectAlternativeNames from X509
>> >
>> > OK.
>> >
>> > Let me be more precise, extracting the information for view sake /
>> validation would be good.
>> > Providing values that are different than what is in the x509 is what I
>> am opposed to.
>> >
>> > +1 for Carlos on the library and that it should be ubiquitously used.
>> >
>> > I will wait for Vijay to speak for himself in this regard…
>> >
>> > -Sam.
>> >
>> >
>> > From: Stephen Balukoff [mailto:sbalukoff at bluebox.net]
>> > Sent: Tuesday, July 15, 2014 8:35 PM
>> > To: OpenStack Development Mailing List (not for usage questions)
>> > Subject: Re: [openstack-dev] [Neutron][LBaaS] TLS capability - SNI -
>> Extracting SubjectCommonName and/or SubjectAlternativeNames from X509
>> >
>> > +1 to German's and  Carlos' comments.
>> >
>> > It's also worth pointing out that some UIs will definitely want to show
>> SAN information and the like, so either having this available as part of
>> the API, or as a standard library we write which then gets used by multiple
>> drivers is going to be necessary.
>> >
>> > If we're extracting the Subject Common Name in any place in the code
>> then we also need to be extracting the Subject Alternative Names at the
>> same place. From the perspective of the SNI standard, there's no difference
>> in how these fields should be treated, and if we were to treat SANs
>> differently then we're both breaking the standard and setting a bad
>> precedent.
>> >
>> > Stephen
>> >
>> >
>> > On Tue, Jul 15, 2014 at 9:35 AM, Carlos Garza <
>> carlos.garza at rackspace.com> wrote:
>> >
>> > On Jul 15, 2014, at 10:55 AM, Samuel Bercovici <SamuelB at Radware.com>
>> >  wrote:
>> >
>> > > Hi,
>> > >
>> > >
>> > > Obtaining the domain name from the x509 is probably more of a
>> driver/backend/device capability, it would make sense to have a library
>> that could be used by anyone wishing to do so in their driver code.
>> >
>> >     You can do what ever you want in *your* driver. The code to extract
>> this information will be apart of the API and needs to be mentioned in the
>> spec now. PyOpenSSL with PyASN1 are the most likely candidates.
>> >
>> > Carlos D. Garza
>> > >
>> > > -Sam.
>> > >
>> > >
>> > >
>> > > From: Eichberger, German [mailto:german.eichberger at hp.com]
>> > > Sent: Tuesday, July 15, 2014 6:43 PM
>> > > To: OpenStack Development Mailing List (not for usage questions)
>> > > Subject: Re: [openstack-dev] [Neutron][LBaaS] TLS capability - SNI -
>> Extracting SubjectCommonName and/or SubjectAlternativeNames from X509
>> > >
>> > > Hi,
>> > >
>> > > My impression was that the frontend would extract the names and hand
>> them to the driver.  This has the following advantages:
>> > >
>> > > ·         We can be sure all drivers can extract the same names
>> > > ·         No duplicate code to maintain
>> > > ·         If we ever allow the user to specify the names on UI rather
>> in the certificate the driver doesn’t need to change.
>> > >
>> > > I think I saw Adam say something similar in a comment to the code.
>> > >
>> > > Thanks,
>> > > German
>> > >
>> > > From: Evgeny Fedoruk [mailto:EvgenyF at Radware.com]
>> > > Sent: Tuesday, July 15, 2014 7:24 AM
>> > > To: OpenStack Development Mailing List (not for usage questions)
>> > > Subject: [openstack-dev] [Neutron][LBaaS] TLS capability - SNI -
>> Extracting SubjectCommonName and/or SubjectAlternativeNames from X509
>> > >
>> > > Hi All,
>> > >
>> > > Since this issue came up from TLS capabilities RST doc review, I
>> opened a ML thread for it to make the decision.
>> > > Currently, the document says:
>> > >
>> > > “
>> > > For SNI functionality, tenant will supply list of TLS containers in
>> specific
>> > > Order.
>> > > In case when specific back-end is not able to support SNI
>> capabilities,
>> > > its driver should throw an exception. The exception message should
>> state
>> > > that this specific back-end (provider) does not support SNI
>> capability.
>> > > The clear sign of listener's requirement for SNI capability is
>> > > a none empty SNI container ids list.
>> > > However, reference implementation must support SNI capability.
>> > >
>> > > Specific back-end code may retrieve SubjectCommonName and/or
>> altSubjectNames
>> > > from the certificate which will determine the hostname(s) the
>> certificate
>> > > is associated with.
>> > >
>> > > The order of SNI containers list may be used by specific back-end
>> code,
>> > > like Radware's, for specifying priorities among certificates.
>> > > In case when two or more uploaded certificates are valid for the same
>> DNS name
>> > > and the tenant has specific requirements around which one wins this
>> collision,
>> > > certificate ordering provides a mechanism to define which cert wins
>> in the
>> > > event of a collision.
>> > > Employing the order of certificates list is not a common requirement
>> for
>> > > all back-end implementations.
>> > > “
>> > >
>> > > The question is about SCN and SAN extraction from X509.
>> > > 1.       Extraction of SCN/ SAN should be done while provisioning and
>> not during TLS handshake
>> > > 2.       Every back-end code/driver must(?) extract SCN and(?) SAN
>> and use it for certificate determination for host
>> > >
>> > > Please give your feedback
>> > >
>> > > Thanks,
>> > > Evg
>> > > _______________________________________________
>> > > OpenStack-dev mailing list
>> > > OpenStack-dev at lists.openstack.org
>> > > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >
>> >
>> > _______________________________________________
>> > OpenStack-dev mailing list
>> > OpenStack-dev at lists.openstack.org
>> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >
>> >
>> >
>> > --
>> > Stephen Balukoff
>> > Blue Box Group, LLC
>> > (800)613-4305 x807
>> > _______________________________________________
>> > OpenStack-dev mailing list
>> > OpenStack-dev at lists.openstack.org
>> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>>
>> _______________________________________________
>> OpenStack-dev mailing list
>> OpenStack-dev at lists.openstack.org
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>>
>
>
>
> --
> Stephen Balukoff
> Blue Box Group, LLC
> (800)613-4305 x807
>



-- 
Stephen Balukoff
Blue Box Group, LLC
(800)613-4305 x807
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