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From: ebiederm@xmission.com (Eric W. Biederman)
To: Dave Hansen <haveblue@us.ibm.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>, Cedric Le Goater <clg@fr.ibm.com>,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
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       Sam Vilain <sam.vilain@catalyst.net.nz>
Subject: Re: [PATCH -mm 5/7] add user namespace
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Date: Fri, 14 Jul 2006 09:13:35 -0600
In-Reply-To: <1152887287.24925.22.camel@localhost.localdomain> (Dave Hansen's
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Dave Hansen <haveblue@us.ibm.com> writes:

> On Thu, 2006-07-13 at 21:45 -0600, Eric W. Biederman wrote:
>> I think for filesystems like /proc and /sys that there will normally
>> be problems.  However many of those problems can be rationalized away
>> as a reasonable optimization, or are not immediately apparent.
>
> Could you talk about some of these problems?

Already mentioned but.  rw permissions on sensitive files are for 
uid == 0.  No capability checks are performed.

>> Passing a file descriptor between process in a unix domain socket is
>> a case where I can easily construct scenarios where there are
>> indisputable problems.  It is one of my standard thought experiments
>> to see if a namespace is sound.
>
> Care to share some of those indisputable problems?

Already done.

Eric