Re: Direct SSL connection with ALPN and HBA rules

On Mon, Apr 22, 2024 at 10:42 PM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Mon, Apr 22, 2024 at 10:47:51AM +0300, Heikki Linnakangas wrote:
> > On 22/04/2024 10:19, Michael Paquier wrote:
> >> As a whole, I can get behind a unique GUC that forces the use of
> >> direct.  Or, we could extend the existing "ssl" GUC with a new
> >> "direct" value to accept only direct connections and restrict the
> >> original protocol (and a new "postgres" for the pre-16 protocol,
> >> rejecting direct?), while "on" is able to accept both.
> >
> > I'd be OK with that, although I still don't really see the point of forcing
> > this from the server side. We could also add this later.
>
> I'd be OK with doing something only in v18, if need be.  Jacob, what
> do you think?

I think it would be nice to have an option like that. Whether it's
done now or in 18, I don't have a strong opinion about. But I do think
it'd be helpful to have a consensus on whether or not this is a
security improvement, or a performance enhancement only, before adding
said option. As it's implemented, if the requiredirect option doesn't
actually requiredirect, I think it looks like security but isn't
really.

(My ideal server-side option removes all plaintext negotiation and
forces the use of direct SSL for every connection, paired with a new
postgresqls:// scheme for the client. But I don't have any experience
making a switchover like that at scale, and I'd like to avoid a
StartTLS-vs-LDAPS sort of situation. That's obviously not a
conversation for 17.)

As for HBA control: overall, I don't see a burning need for an
HBA-based configuration, honestly. I'd prefer to reduce the number of
knobs and make it easier to apply the strongest security with a broad
brush.

--Jacob