Re: RFC: Non-user-resettable SET SESSION AUTHORISATION

Bruce Momjian wrote:
> On Sun, May 17, 2015 at 09:31:47PM +0200, José Luis Tallón wrote:
> > On 05/17/2015 07:39 PM, Tom Lane wrote:
> > >José Luis Tallón <jltallon@adv-solutions.net> writes:
> > >>On the other hand, ISTM that what we all intend to achieve is some
> > >>Postgres equivalent of the SUID bit... so why not just do something
> > >>equivalent?
> > >>-------
> > >>      LOGIN    -- as user with the appropriate role membership / privilege?
> > >>      ...
> > >>      SET ROLE / SET SESSION AUTHORIZATION WITH COOKIE / IMPERSONATE
> > >>      ... do whatever ...    -- unprivileged user can NOT do the
> > >>"impersonate" thing
> > >>      DISCARD ALL    -- implicitly restore previous authz
> > >>-------
> > >Oh?  What stops the unprivileged user from doing DISCARD ALL?
> >
> > Indeed. The pooler would need to block this.
> > Or we would need to invent another (this time, privileged) verb in
> > order to restore authz.
>
> What if you put the SQL in a function then call the function?  I don't
> see how the pooler could block this.

I think the idea of having SET SESSION AUTH pass a cookie, and only let
RESET SESSION AUTH work when the same cookie is supplied, is pretty
reasonable.