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From: Vivek Khera <vivek@khera.org>
Date: Tue, 4 Apr 2006 10:07:44 -0400
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Subject: Re: [HACKERS] semaphore usage "port based"?
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On Apr 3, 2006, at 3:41 PM, Daniel Eischen wrote:

>> ... and you *still* haven't shown *why* kill() reporting a PID is  
>> in use,
>> even if its not in the current jail, is such a security threat ...
>
> For reducing attacks I suppose.  But conceptually, something running
> in a jail shouldn't be allowed to see out.

I don't think it gives you much information given that PIDs come and  
go and there's no atomicity in checking if it exists, and then  
finding what it is.  Even on the same jail the PID could go away  
after you check for it before you try to pry into what it is or do  
something else.

I think it is an overly paranoid attempt at hiding information that  
is otherwise useful.  At worst there should be a sysctl to enable it.