Re: [PoC] Federated Authn/z with OAUTHBEARER

> This really doesn't feel like a great area to try and do hooks or
> similar in, not the least because that approach has been tried and tried
> again (PAM, GSSAPI, SASL would all be examples..) and frankly none of
> them has turned out great (which is why we can't just tell people "well,
> install the pam_oauth2 and watch everything work!") and this strikes me
> as trying to do that yet again but worse as it's not even a dedicated
> project trying to solve the problem but more like a side project.

In this case it's not intended to be an open-ended hook, but rather an
implementation of a specific rfc (rfc-7628) which defines a
client-server communication for the authentication flow.
The rfc itself does leave a lot of flexibility on specific parts of
the implementation. Which do require hooks:
(1.) Server side hook to validate the token, which is specific to the
OAUTH provider.
(2.) Client side hook to request the client to obtain the token.

On (1.), we would need a hook for the OAUTH provider extension to do
validation. We can though do some basic check that the credential is
indeed a JWT token signed by the requested issuer.

Specifically (2.) is where we can provide a layer in libpq to simplify
the integration. i.e. implement some OAUTH flows.
Though we would need some flexibility for the clients to bring their own token:
For example there are cases where the credential to obtain the token
is stored in a separate secure location and the token is returned from
a separate service or pushed from a more secure environment.

> another new "generic" set of hooks/APIs that will just cause DBAs and
> our users headaches trying to make work.
As I mentioned above, it's an rfc implementation, rather than our invention.
When it comes to DBAs and the users.
Builtin libpq implementations which allows psql and pgadmin to
seamlessly connect should suffice those needs.
While extensibility would allow the ecosystem to be open for OAUTH
providers, SAAS developers, PAAS providers and other institutional
players.

Thanks!
Andrey.

On Thu, Feb 23, 2023 at 10:47 AM Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>
> Greetings,
>
> * Jacob Champion (jchampion(at)timescale(dot)com) wrote:
> > On Mon, Feb 20, 2023 at 2:35 PM Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> > > Having skimmed back through this thread again, I still feel that the
> > > direction that was originally being taken (actually support something in
> > > libpq and the backend, be it with libiddawc or something else or even
> > > our own code, and not just throw hooks in various places) makes a lot
> > > more sense and is a lot closer to how Kerberos and client-side certs and
> > > even LDAP auth work today.
> >
> > Cool, that helps focus the effort. Thanks!
>
> Great, glad to hear that.
>
> > > That also seems like a much better answer
> > > for our users when it comes to new authentication methods than having
> > > extensions and making libpq developers have to write their own custom
> > > code, not to mention that we'd still need to implement something in psql
> > > to provide such a hook if we are to have psql actually usefully exercise
> > > this, no?
> >
> > I don't mind letting clients implement their own flows... as long as
> > it's optional. So even if we did use a hook in the end, I agree that
> > we've got to exercise it ourselves.
>
> This really doesn't feel like a great area to try and do hooks or
> similar in, not the least because that approach has been tried and tried
> again (PAM, GSSAPI, SASL would all be examples..) and frankly none of
> them has turned out great (which is why we can't just tell people "well,
> install the pam_oauth2 and watch everything work!") and this strikes me
> as trying to do that yet again but worse as it's not even a dedicated
> project trying to solve the problem but more like a side project. SCRAM
> was good, we've come a long way thanks to that, this feels like it
> should be more in line with that rather than trying to invent yet
> another new "generic" set of hooks/APIs that will just cause DBAs and
> our users headaches trying to make work.
>
> > > In the Kerberos test suite we have today, we actually bring up a proper
> > > Kerberos server, set things up, and then test end-to-end installing a
> > > keytab for the server, getting a TGT, getting a service ticket, testing
> > > authentication and encryption, etc. Looking around, it seems like the
> > > equivilant would perhaps be to use Glewlwyd and libiddawc or libcurl and
> > > our own code to really be able to test this and show that it works and
> > > that we're doing it correctly, and to let us know if we break something.
> >
> > The original patchset includes a test server in Python -- a major
> > advantage being that you can test the client and server independently
> > of each other, since the implementation is so asymmetric. Additionally
> > testing against something like Glewlwyd would be a great way to stack
> > coverage. (If we *only* test against a packaged server, though, it'll
> > be harder to test our stuff in the presence of malfunctions and other
> > corner cases.)
>
> Oh, that's even better- I agree entirely that having test code that can
> be instructed to return specific errors so that we can test that our
> code responds properly is great (and is why pgbackrest has things like
> a stub'd out libpq, fake s3, GCS, and Azure servers, and more) and would
> certainly want to keep that, even if we also build out a test that uses
> a real server to provide integration testing with not-our-code too.
>
> Thanks!
>
> Stephen