Re: Error from the foreign RDBMS on a foreign table I have no privilege on - Mailing list pgsql-hackers

At Wed, 08 Jun 2022 07:05:09 +0200, Laurenz Albe <laurenz.albe@cybertec.at> wrote in 
> I take Tom's comment above as saying that the current behavior is fine.
> So yes, perhaps some documentation would be in order:
> 
> diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
> index b43d0aecba..b4b7e36d28 100644
> --- a/doc/src/sgml/postgres-fdw.sgml
> +++ b/doc/src/sgml/postgres-fdw.sgml
> @@ -274,6 +274,14 @@ OPTIONS (ADD password_required 'false');
>         but only for that table.
>         The default is <literal>false</literal>.
>        </para>
> +
> +      <para>
> +       Note that <command>EXPLAIN</command> will be run on the remote server
> +       at query planning time, <emphasis>before</emphasis> permissions on the
> +       foreign table are checked.  This is not a security problem, since the
> +       subsequent error from the permission check will prevent the user from
> +       seeing any of the resulting data.
> +      </para>
>       </listitem>
>      </varlistentry>

Looks fine.  I'd like to add something like "If needed, depriving
unprivileged users of relevant user mappings will prevent such remote
executions that happen at planning-time."

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center