Re: postgres_fdw super user checks

On Mon, Oct 17, 2016 at 3:33 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> postgres_fdw has some checks to enforce that non-superusers must connect to
> the foreign server with a password-based method. The reason for this is to
> prevent the authentication to the foreign server from happening on the basis
> of the OS user who is running the non-foreign server.
>
> But I think these super user checks should be run against the userid of the
> USER MAPPING being used for the connection, not the userid of currently
> logged on user.

So, if the user mapping user is a superuser locally, this would allow
any lambda user of the local server to attempt a connection to the
remote server. It looks dangerous rather dangerous to me to authorize
that, even if the current behavior is a bit inconsistent I agree.

Your patch breaks the join pushdown logic when multiple user IDs are
involved. Per se make check.
--
Michael