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Subject: Re: [PATCH] new setprocuid syscall
To: peter@cadcamlab.org (Peter Samuelson)
Date: Tue, 20 Feb 2001 13:52:03 +0000 (GMT)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), linux-kernel@vger.kernel.org
In-Reply-To: <14994.27891.171934.348706@wire.cadcamlab.org> from "Peter Samuelson" at Feb 20, 2001 07:11:15 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> Fair enough but could you explain the potential problems?  And how is
> it different from sys_setpriority?

Suppose you change a tasks uid in parallel with the set of conditionals
in setuid - just as one example. Or you change uid _during_ a quota operation.
Or during sys5 ipc ops.

All of these and more make assumptions. The idea of locking uid changes with
semaphores would produce some truely horrible performance impacts

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