Message-ID: <4935EADC.3070407@davidnewall.com>
Date: Wed, 03 Dec 2008 12:41:40 +1030
From: David Newall <davidn@davidnewall.com>
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To: Geoffrey McRae <geoff@rabidhost.com>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: Re: New Security Features, Please Comment
References: <1228260494.24232.21.camel@compy.ivent.com.au>	 <20081203005338.6472db7a@lxorguk.ukuu.org.uk> <1228268657.6679.4.camel@lappy.spacevs.com>
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Geoffrey McRae wrote:
> But once this set is introduced a HTTP server could be written that uses
> forked children to handle requests, that have their identity swtiched
> before doing any work, including parsing CGI scripts.

But a child could be one user the first time it does work, and another
user the next time.  What prevents the child from opening a file while
the first user, and reading or writing it while the second?  That's
exactly what you don't want to permit.
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