linux-kernel - Re: Building a BSD-jail clone out of namespaces

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Date:	Thu, 6 Jun 2013 17:46:52 +0100
From:	Chris Webb <chris@...chsys.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Building a BSD-jail clone out of namespaces

"Eric W. Biederman" <ebiederm@...ssion.com> writes:

> That will work, but you really don't want to run with uid == 0 mapped to
> uid == 0.  There are too many things in /proc and /sys and similar that
> grant access to uid == 0.

Many thanks for the swift reply. If I map UID zero in the userns to a
non-zero UID outside (say -1), is there any way to use the userns UIDs
instead of host UIDs when accessing the container's root filesystem so I
don't end up with strange file ownerships on disk? This would prevent me
from using the same filesystem on physical hosts or in VMs.

I don't think there's any kernel mechanism that lets me apply a UID
translation layer as part of a bind mount is there?

Cheers,

Chris.
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