Message-ID: <48940239.8080401@tada.se>
Date: Sat, 02 Aug 2008 08:44:09 +0200
From: Thomas Hallgren <thomas@tada.se>
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: Kris Jurka <books@ejurka.com>, pljava-dev@pgfoundry.org,
	Alvaro Herrera <alvherre@commandprompt.com>, pgsql-hackers@postgresql.org
Subject: Re: Re: [Pljava-dev] Should creating a new base type require
	superuser status?
References: <19715.1217447413@sss.pgh.pa.us>
	<20080730220753.GG3977@alvh.no-ip.org>
	<Pine.BSO.4.64.0807311543170.14232@leary.csoft.net>
	<23846.1217539394@sss.pgh.pa.us> <48937589.10304@tada.se>
	<23725.1217626961@sss.pgh.pa.us>
In-Reply-To: <23725.1217626961@sss.pgh.pa.us>
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Tom Lane wrote:
> Thomas Hallgren <thomas@tada.se> writes:
>   
>> Tom, could you please elaborate where you see a security hole?
>>     
>
> The problem that we've seen in the past shows up when the user lies in
> the CREATE TYPE command, specifying type representation properties that
> are different from what the underlying functions expect.  In particular,
> if it's possible to pass a pass-by-value integer to a function
> that's expecting a pass-by-reference datum, you can misuse the function
> to access backend memory.
>
>   
This is a non-issue in PL/Java. An integer parameter is never passed by 
reference and there's no way the PL/Java user can get direct access to 
backend memory.

> I gather from looking at the example that Kris referenced that there's
> some interface code in between the SQL function call and the user's Java
> code, and that that interface code is itself looking at the declared
> properties of the SQL type to decide what to do.  So to the extent that
> that code is (a) bulletproof against inconsistencies and (b) not
> subvertible by the PL/Java user, it might be that there's no hole in
> practice.  But assumption (b) seems pretty fragile to me.
>
>   
I think that assumption is without ground. Java doesn't permit you to 
access memory unless you use Java classes (java.nio stuff) that is 
explicitly designed to do that and you need native code to set such 
things up. A PL/Java user can not do that unless he is able to link in 
other shared objects or dll's to the backend process.

Based on that, I claim that your statement about a "security hole a mile 
wide" is incorrect. PL/Java is not subject to issues relating to misuse 
of backend memory.

Regards,
Thomas Hallgren