To: "Lars Olson" <leolson1@uiuc.edu>
cc: pgsql-bugs@postgresql.org
Subject: Re: BUG #4074: Using SESSION_USER or CURRENT_USER in a view
	definition is unsafe
In-reply-to: <200803312055.m2VKtmdb090699@wwwmaster.postgresql.org> 
References: <200803312055.m2VKtmdb090699@wwwmaster.postgresql.org>
Comments: In-reply-to "Lars Olson" <leolson1@uiuc.edu>
	message dated "Mon, 31 Mar 2008 20:55:48 +0000"
Date: Mon, 31 Mar 2008 17:46:48 -0400
Message-ID: <24862.1207000008@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Lars Olson" <leolson1@uiuc.edu> writes:
> Creating a view that depends on the value of SESSION_USER enables a
> minimally-privileged user to write a user-defined function that contains a
> trojan-horse to get arbitrary data from the base table.

This example proves nothing except that you shouldn't execute untrusted
code --- Carol gave up her data by willingly executing Bob's function.
I don't think that the use of SESSION_USER is particularly to blame.
There are certainly any number of other ways Bob could have abused
her trust here.

> This is highly related to a paper I am preparing for a security conference
> that I am submitting in two weeks.  Sorry about the short notice, I only
> just thought of this problem yesterday.  I would like to use this as an
> example in my paper, but I will not do so without PostgreSQL's permission. 
> Please advise.

If this were a security issue, you already spilled the beans by
reporting it to a public mailing list; so I'm unsure what you are
concerned about.

			regards, tom lane