Re: [v9.2] Add GUC sepgsql.client_label

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Yeb Havinga <yebhavinga(at)gmail(dot)com>, Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp>, PgHacker <pgsql-hackers(at)postgresql(dot)org>, Joshua Brindle <jbrindle(at)tresys(dot)com>
Subject: Re: [v9.2] Add GUC sepgsql.client_label
Date: 2012-01-31 20:55:16
Message-ID: 10214.1328043316@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> ....and that's bad. More generally, the system security policy is
> designed to answer questions about whether it's OK to transition from
> A->B, and the fact that A->B is OK does not mean that B->A is OK, but
> our GUC mechanism pretty much forces you to allow both of those
> things, or neither.

More to the point, a GUC rollback transition *has to always succeed*.
Period. Now, the value that it's trying to roll back to was presumably
considered legitimate at some previous time, but if you're designing a
system that is based purely on state transitions it could very well see
the rollback transition as invalid. That is just going to be too
fragile to be acceptable.

I think that this will have to be set up so that it understands the
difference between a forward transition and a rollback and only checks
the former. If that's not possible, this is not going to get in.

regards, tom lane

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