From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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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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Lists: | pgsql-hackers |
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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