Message-ID: <3FFB3B44.9060106@zytor.com>
Date: Tue, 06 Jan 2004 14:48:36 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
Organization: Zytor Communications
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To: Dax Kelson <dax@gurulabs.com>
CC: thockin@Sun.COM, Mike Waychison <Michael.Waychison@Sun.COM>,
       autofs mailing list <autofs@linux.kernel.org>,
       Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: name spaces good
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Dax Kelson wrote:
> On Tue, 2004-01-06 at 15:06, H. Peter Anvin wrote:
> 
>>First of all, I'll be blunt: namespaces currently provide zero benefit
>>in Linux, and virtually noone uses them.
> 
> 
> I strongly disagree.
> 
> I find them very useful, and there are lots of problems that are not
> cleanly solved any other way. In particular they are very useful in
> security hardening, compartmentalization scenarios.
> 

Excellent... if so it would be useful to have a discussion about the
proper semantics for these scenarios.  So far the consensus opinion
among most of the VFS people seems to have been "when you clone a
namespace you get an unanimated namespace"; it would be useful ito know
if that applies to your scenario, assuming it matters, and if so why/why
not.

Al Viro has been working on a key piece of infrastructure for doing
autofs right called mount traps.  This is the main reason -- even more
so than the lack of time on my part -- that not much work has been done
on the new version of autofs.  mount traps, combined with
"pseudo-symlinks" (non-S_IFLNK nodes which have follow_link methods), do
most of the tasks that have been proven necessary in the kernel.

The consensus I have seen seems to be that namespaces is mostly used, as
you said, for compartmentalizing and security, you pretty much have two
scenarios as far as I can see it:

a) You're running autofs "outside" the compartmentalization, in a global
namespace.
b) You're running autofs "inside" the compartmentalization, then you
don't want access to anything on the outside.  You thus run the autofs
"inside" and can't access anything else.

	-hpa

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