Message-ID: <46F2DDD0.3030500@tmr.com>
Date: Thu, 20 Sep 2007 16:53:36 -0400
From: Bill Davidsen <davidsen@tmr.com>
Organization: TMR Associates Inc, Schenectady NY
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To: David Newall <david@davidnewall.com>
CC: Philipp Marek <philipp@marek.priv.at>, 7eggert@gmx.de,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, majkls <majkls@prepere.com>,
       bunk@fs.tum.de, linux-kernel@vger.kernel.org
Subject: Re: sys_chroot+sys_fchdir Fix
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David Newall wrote:
> Philipp Marek wrote:
>> AFAIK pivot_root() changes the / mapping for *all* processes, no?
>>   
>
> The manual page is confusing.  It even admits to being "intentionally 
> vague".  However the goal seems clear:
>
>    "pivot_root() moves the root file system of the current process to
>    the directory put_old and makes new_root the new root file system of
>    the current process"
>    -- man 2 pivot_root
>
> There's an argument that pivot_root could be improved...
>
And very little argument that the man page could be improved, perhaps. 
However, there is no question that pivot_root is intended to have 
breadth for more than one process.

Keeping this functionality sounds a little like putting a bow tie and 
tux on your bug and calling it a "feature." Not all bugs are useless for 
legitimate purposes, but it doesn't make them safe. It appears to be a 
sort-of way to get per-process bind mounts.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

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