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Date:      Mon, 3 Apr 2006 23:51:52 +0100 (BST)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        "Marc G. Fournier" <scrappy@hub.org>
Cc:        Daniel Eischen <deischen@freebsd.org>, Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-stable@freebsd.org
Subject:   Re: [HACKERS] semaphore usage "port based"?
Message-ID:  <20060403234918.X76562@fledge.watson.org>
In-Reply-To: <20060403163039.O947@ganymede.hub.org>
References:  <Pine.GSO.4.43.0604031454030.22397-100000@sea.ntplx.net> <20060403163039.O947@ganymede.hub.org>

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On Mon, 3 Apr 2006, Marc G. Fournier wrote:

> This falls under "well,we broke kill() so that it now reports a PID is not 
> in use even though it is, so its has to be the application that fixes it" 
> ... 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 ...

It is an issue of completeness and consistency.  We implement a single set of 
access control checks between processes, and try to avoid exceptions to them. 
This is one of my largest architectural gripes about access control in 4.x, 
actually: everywhere you look, the same "check" is implemented differently. 
Sometimes signal checks are done way, other times, other ways.  Likewise, 
debugging, monitoring, etc.  In 5.x forward, we use a centralized set of 
access control checks in order to provide consistent, reliable, and easy to 
analyze policy.  The more exceptions we introduced, the further we get from 
that goal.

Robert N M Watson



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