Re: postgres_fdw, dblink, and CREATE SUBSCRIPTION security

On Wed, Mar 8, 2023 at 2:30 PM Jacob Champion <jchampion(at)timescale(dot)com> wrote:
> > No, that's the opposite, and exactly the point I'm trying to make. In
> > that case, the SERVER says what it's willing to accept, and the CLIENT
> > decides whether or not to provide that. In your proposal, the client
> > tells the server which authentication methods to accept.
>
> Ah, that's a (the?) sticking point. In my example, the client doesn't
> tell the server which methods to accept. The client tells the server
> which method the *client* has the ability to use. (Or, implicitly,
> which methods it refuses to use.)
>
> That shouldn't lose any power, security-wise, because the server is
> looking for an intersection of the two sets. And the client already
> has the power to do that for almost every form of authentication,
> except the ambient methods.
>
> I don't think I necessarily like that option better than SASL-style,
> but hopefully that clarifies it somewhat?

Hmm, yeah, I guess that's OK. I still don't love it, though. It feels
more solid to me if the proxy can actually block the connections
before they even happen, without having to rely on a server
interaction to figure out what is permissible.

I don't know what you mean by SASL-style, exactly.

--
Robert Haas
EDB: http://www.enterprisedb.com