From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>, Andreas Pflug <pgadmin(at)pse-consulting(dot)de>, PostgreSQL Patches <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: logfile subprocess and Fancy File Functions |
Date: | 2004-07-24 16:12:52 |
Message-ID: | 200407241612.i6OGCq906623@candle.pha.pa.us |
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Lists: | pgsql-patches |
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Thinking we have security because they can't guess
> > pgdata seems like security through obscurity to me.
>
> Sure, but it's still a useful roadblock to throw in an attacker's way.
>
> I spent many years doing computer security stuff, and one thing I
> learned is that the more layers of security you can have, the better.
> You don't put all your faith in any one roadblock; you erect a series
> of them that an attacker will have to break through all of. If some
> of 'em are a little porous, that doesn't make 'em useless.
>
> In today's context, I think the main point of requiring an attacker
> to guess $PGDATA is that it helps avoid the "software monoculture"
> syndrome. If someone did manage to write a Postgres-based virus that
> involved an exploit in this area, it could only spread to machines
> that had the $PGDATA value the virus writer was expecting.
As a super-user, could an attacker load a server-side language and
access the backend environment variable PGDATA. Also look at this:
test=> CREATE FUNCTION "xxx_call_handler" () RETURNS language_handler AS '$libdir/pltcl' LANGUAGE C;
ERROR: could not find function "xxx_call_handler" in file "/usr/var/local/postgres/lib/pltcl.so"
Notice the expansion of "$libdir".
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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