linux-kernel - Re: [RFC/PATCH] revoke/frevoke system calls V2

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Date:	Mon, 7 Aug 2006 17:24:08 -0500 (CDT)
From:	Chase Venters <chase.venters@...entec.com>
To:	Edgar Toernig <froese@....de>
cc:	Pekka Enberg <penberg@...helsinki.fi>, Pavel Machek <pavel@....cz>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	akpm@...l.org, viro@...iv.linux.org.uk, alan@...rguk.ukuu.org.uk,
	tytso@....edu, tigran@...itas.com
Subject: Re: [RFC/PATCH] revoke/frevoke system calls V2

On Mon, 7 Aug 2006, Edgar Toernig wrote:

>
> Your implementation is much cruder - it simply takes the fd
> away from the app; any future use gives EBADF.  As a bonus,
> it works for regular files and even goes as far as destroying
> all mappings of the file from all processes (even root processes).
> IMVHO this is a disaster from a security and reliability point
> of view.
>

I can see the value in these system calls, but I agree that the 
implementation is crude. "EBADF" is not something that applications are 
taught to expect. Someone correct me if I'm wrong, but I can think of no 
situation under which a file descriptor currently gets yanked out from 
under your feet -- you should always have to formally abandon it with 
close().

This kind of thing only looks proper if it leaves the file descriptor in 
place and just returns errors / EOF when you attempt to access it.

Thanks,
Chase
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