Re: advisory locks and permissions

On Sep 22, 2006, at 11:26 , Merlin Moncure wrote:

> On 9/22/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Stephen Frost <sfrost@snowman.net> writes:
>> > * Tom Lane (tgl@sss.pgh.pa.us) wrote:
>> >> An admin who is concerned about this can revoke public access  
>> on the
>> >> functions for himself ... but should that be the default out-of- 
>> the-box
>> >> configuration?  I feel more comfortable with saying "you have  
>> to turn
>> >> on this potentially-dangerous feature" than with saying you  
>> have to turn
>> >> it off.
>>
>> > I agree with having it turned off by default, at least in 8.2.
>>
>> Do we have a consensus to do this for 8.2?  Or are we going to  
>> leave it
>> as is?  Those are the only two realistic short-term options ...
>
> there are plenty of other potentially nasty things (like
> generate_series and the ! operator).  why are advisory_locks handled
> specially?   the way it stands right now is a user with command access
> can DoS a server after five minutes of research on the web.
>
> however, if we decide to lock them,  it should be documented as such.
>
> advisory locks still show up as 'userlock' in the pg_locks view.  does
> this matter?

I would be more worried about accidental collisions between  
applications. The lock ranges will now need to be in their respective  
application's configuration file in case of collision with another  
app once developers really start using locks for IPC. Ideally, the  
user-level lock functions would take strings instead of integers and  
hash them appropriately, no? Otherwise, someone will end up  
maintaining a registry of lock numbers in use. LISTEN doesn't use  
integers.

-M