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Date:      Mon, 3 Apr 2006 16:37:11 +1200
From:      Andrew Thompson <thompsa@freebsd.org>
To:        "Marc G. Fournier" <scrappy@postgresql.org>
Cc:        freebsd-stable@freebsd.org, Kris Kennaway <kris@obsecurity.org>
Subject:   Re: [HACKERS] semaphore usage "port based"?
Message-ID:  <20060403043711.GB76193@heff.fud.org.nz>
In-Reply-To: <20060403011401.I947@ganymede.hub.org>
References:  <20060402232832.M947@ganymede.hub.org> <20060402234459.Y947@ganymede.hub.org> <27417.1144033691@sss.pgh.pa.us> <20060403031157.GA57914@xor.obsecurity.org> <27515.1144034269@sss.pgh.pa.us> <20060403032130.GA58053@xor.obsecurity.org> <20060403002830.W947@ganymede.hub.org> <20060403034101.GA58429@xor.obsecurity.org> <20060403035911.GA76193@heff.fud.org.nz> <20060403011401.I947@ganymede.hub.org>

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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.


Andrew



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