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Re: Updates of SE-PostgreSQL 8.4devel patches

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Updates of SE-PostgreSQL 8.4devel patches
Date: 2008-09-27 03:05:49
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Lists: pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > I am confused how knowing that a sequence number used for a primary key
> > exists or doesn't exist is leaking _meaningful_ information.  People
> > might know the sequence number exists, but how is that information
> > useful.  Now, if natural keys are used, that is a different story.
> Right.  It might be that securing a database requires not just some
> security mechanisms but also some database design rules (like "don't
> allow foreign keys except on synthetic IDs").  But it seems to me that
> we are just flailing around in the dark because we don't have that
> bigger picture of how the features would actually get used.
> The literature pointers that Andrew just gave us seem promising to me.
> Who's going to go searching for some useful info?

I found this paper from 1996:

Full PDF at link in right column.  The interesting chapters are chapter
and chapter 4, "COVERT CHANNELS".  It mentions "polyinstantiation":

	These security considerations have led to the notion of
	polyinstantiation [Denning 87]. Polyinstantiation forces a relation to
	contain multiple tuples with the same primary key but distinguishable by
	their classification levels or by the non-primary key attributes of the
	relation [Lunt 91].

which I think we want to avoid.  It also talks about cases where the
primary and foreign key rows have identical or different security
settings.  It talks about "COVERT CHANNELS", which is information

And it mentions TCSEC (Trusted Computer System Evaluation Criteria):

which I think is the proper term for the security target we are trying
to address, or at least one of the targets.

  Bruce Momjian  <bruce(at)momjian(dot)us>

  + If your life is a hard drive, Christ can be your backup. +

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