[HACKERS] semaphore usage "port based"?

[Marc G. Fournier]

On Mon, 3 Apr 2006, Andrew Thompson wrote:

> On Mon, Apr 03, 2006 at 01:23:59AM -0300, Marc G. Fournier wrote:
>>
>> taking it off of pgsql-hackers, so that we don't annoy them unnecessarily
>> ...
>>
>> 'k, looking at the code, not that most of it doesn't go over my head ...
>> but ...
>>
>> in kern/kern_jail.c, I can see the prison_check() call ... wouldn't one
>> want to make the change a bit further up?  say in kern_prot.c?  wouldn't
>> you want to change just cr_cansignal() to allow *just* for 'case 0', when
>> someone is just checking to see if a process is already running?  I
>> wouldn't want to be able to SIGKILL the process from a different jail,
>> mind you ... maybe move the check for SIG0 to just before the
>> prison_check, since, unless I'm missing something, other then determining
>> that a process is, in fact, running, SIG0 is a benign signal?
>>
>
> I think the suggestion was to make this EPERM rather than ESRCH to make
> postgres a bit happier, not remove the check entirely. Im not familiar
> with that part of the kernel at all, so I cant say what the consequences
> will be apart from the obvious information leak.

'k, first question is 'what information leak' are we trying to protect 
from?  to 'make postgres a bit happier', all that needs to be fixed, from 
what I can tell, is that cr_cansignal() needs to work for signal 0, but no 
other signals ... what risk of information leak does that create?

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy at hub.org           Yahoo!: yscrappy              ICQ: 7615664