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From: Peter Samuelson <peter@cadcamlab.org>
To: BERECZ Szabolcs <szabi@inf.elte.hu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] new setprocuid syscall
Date: Tue, 20 Feb 2001 22:19:43 -0600	[thread overview]
Message-ID: <20010220221943.A28652@cadcamlab.org> (raw)
In-Reply-To: <E14VDD2-0006ha-00@the-village.bc.nu> <Pine.A41.4.31.0102201759300.50000-100000@pandora.inf.elte.hu>
In-Reply-To: <Pine.A41.4.31.0102201759300.50000-100000@pandora.inf.elte.hu>; from szabi@inf.elte.hu on Tue, Feb 20, 2001 at 06:04:09PM +0100


[BERECZ Szabolcs]
> The conclusion: it's cannot be implemented without slowdown.

Or: it cannot be implemented 100% safely and correctly without slowdown.

If you know the use you wish to put this to, and are willing to risk a
permission check somewhere being confused momentarily by a non-atomic
update of a 32-bit number (or the non-atomic update between several
32-bit numbers, which I think is less serious because then you are not
granting more than the union of the two UIDs) go ahead and patch your
kernel.

> So ignore my patch.

For official kernels, I agree.  They need to be as safe and
deterministic as possible, especially security-wise, and a semaphore on
every permission check would be ridiculous.

Peter

  parent reply	other threads:[~2001-02-21  4:20 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-02-19 22:18 BERECZ Szabolcs
2001-02-20  5:01 ` Peter Samuelson
2001-02-20 10:53   ` Martin Dalecki
2001-02-20 13:00     ` Peter Samuelson
2001-02-20 11:42   ` Alan Cox
2001-02-20 13:11     ` Peter Samuelson
2001-02-20 13:52       ` Alan Cox
2001-02-20 17:04         ` BERECZ Szabolcs
2000-01-01  0:28           ` Pavel Machek
2001-02-21  4:19           ` Peter Samuelson [this message]
2001-02-20 12:14   ` BERECZ Szabolcs
2001-02-20 12:52     ` Peter Samuelson
2001-02-20 12:02 ` Philipp Rumpf
2001-02-20 14:19 Petr Vandrovec
2001-02-23 17:13 Bernd Jendrissek

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