Subject: Re: dump/restore problem due to CVE-2018-1058 (9.5.12)
To: Rory Campbell-Lange <rory@campbell-lange.net>,
 pgsql-general@postgresql.org
References: <20180407192757.utugzd2zbwbtwoui@campbell-lange.net>
From: Adrian Klaver <adrian.klaver@aklaver.com>
Message-ID: <a0dc9bf9-ef82-6f2c-b1f4-0087644981ba@aklaver.com>
Date: Sat, 7 Apr 2018 12:46:52 -0700
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On 04/07/2018 12:27 PM, Rory Campbell-Lange wrote:
> Hi
> 
> Following an upgrade to 9.5.12, we cannot restore some of our databases
> due to a schema qualification issue introduced in the new postgres
> version of pg_dump.
> 
> Specifically, the problem line is the addition of :
> 
>      SELECT pg_catalog.set_config('search_path', '', false);
> 
> to the header of the pg_dump output.
> 
> As a result, pg_restore now fails because we have some table constraints
> that use functions which do not use public schema qualified table/column
> references.
> 
> (I'm aware that the reasons behind the change made to the dump format
> due to CVE-2018-1058 are set out here:
> https://wiki.postgresql.org/wiki/A_Guide_to_CVE-2018-1058:_Protect_Your_Search_Path)
> 

> Additionally we sometimes use search_path manipulations +
> temporary_schema.function to test functions in production environments.
> Having to qualify the schema of objects seems a retrogressive step, but
> perhaps our usage is peculiar in this way.

AFAIK you can still do that or did I miss something?

> 
> Also, in a coding environment where object.attribute masking is a
> feature of the language, as it is in python, this change seems obtuse.
> My function in schema x can still mask a function in another schema y,
> so the problem of function masking (if it is a problem) still exists.

Are talking Python external or internal to Postgres?

If internal, then plpythonu is an untrusted language and can only be 
used by a superuser. If you are a superuser then there is host of other 
things you could do to compromise security as well.


> 
> Thanks for any comments.
>      
> Regards
> Rory
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com