From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Noah Misch <noah@leadboat.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Subject: Re: Converting contrib SQL functions to new style
In-reply-to: 
 <CA+TgmobdzZc2UET6z_=e_Uia63Btb3jMX2bVSukWvE21y75o-g@mail.gmail.com>
References: <3395418.1618352794@sss.pgh.pa.us>
 <20210414020827.GA1232417@rfd.leadboat.com>
 <3441172.1618369873@sss.pgh.pa.us>
 <20210414125811.GB1263822@rfd.leadboat.com>
 <CA+TgmoaF_DKSPRnbkakkOufWMFpOBsA8fwE-mF0fF7aeH20zqg@mail.gmail.com>
 <3489827.1618411777@sss.pgh.pa.us>
 <CA+TgmoYQB1qxb=v9xVi09-f_HRDDqwUwfcuNpsZ2SF-ePpWJcw@mail.gmail.com>
 <3566011.1618422104@sss.pgh.pa.us>
 <CA+TgmobdzZc2UET6z_=e_Uia63Btb3jMX2bVSukWvE21y75o-g@mail.gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Wed, 14 Apr 2021 13:56:34 -0400"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <3567048.1618423436.1@sss.pgh.pa.us>
Date: Wed, 14 Apr 2021 14:03:56 -0400
Message-ID: <3567049.1618423436@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/3567049.1618423436%40sss.pgh.pa.us>
Precedence: bulk

Robert Haas <robertmhaas@gmail.com> writes:
> On Wed, Apr 14, 2021 at 1:41 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Could we hack things so that extension scripts are only allowed to
>> reference objects created (a) by the system, (b) earlier in the
>> same script, or (c) owned by one of the declared prerequisite
>> extensions?  Seems like that might provide a pretty bulletproof
>> defense against trojan-horse objects, though I'm not sure how much
>> of a pain it'd be to implement.

> That doesn't seem like a crazy idea, but the previous idea of having
> some magic syntax that means "the schema where extension FOO is" seems
> like it might be easier to implement and more generally useful.

I think that's definitely useful, but it's not a fix for the
reference-capture problem unless you care to assume that the other
extension's schema is free of trojan-horse objects.  So I'm thinking
that we really ought to pursue both ideas.

This may mean that squeezing these contrib changes into v14 is a lost
cause.  We certainly shouldn't try to do what I suggest above for
v14; but without it, these changes are just moving the security
issue to a different place rather than eradicating it completely.

			regards, tom lane