Re: FPW compression leaks information

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: Stephen Frost <sfrost(at)snowman(dot)net>
Cc: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: FPW compression leaks information
Date: 2015-04-09 22:57:30
Message-ID: CAB7nPqQvRZshTc8TWq9-F+hy62x=TcbbfCshaPYh7pJH5uo91w@mail.gmail.com
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On Fri, Apr 10, 2015 at 1:07 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> * Heikki Linnakangas (hlinnaka(at)iki(dot)fi) wrote:
>> On 04/09/2015 06:28 PM, Stephen Frost wrote:
>> >* Heikki Linnakangas (hlinnaka(at)iki(dot)fi) wrote:
>> >>What should we do about this? Make it configurable on a per-table
>> >>basis? Disable FPW compression on system tables? Disable FPW on
>> >>tables you don't have SELECT access to? Add a warning to the docs?
>> >
>> >REVOKE EXECUTE ON FUNCTION pg_current_xlog_insert_location() FROM public;
>>
>> Yeah, that's one option. Will also have to revoke access to
>> pg_stat_replication and anything else that might indirectly give
>> away the current WAL position.
>
> Sure, though pg_stat_replication already only returns the PID and no
> details, unless you're a superuser.

For consistency we may want to have the same behavior for
pg_current_xlog_insert_location(), pg_last_xlog_receive_location(),
pg_current_xlog_location() and pg_last_xlog_replay_location().
--
Michael

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