linux-kernel - Re: [PATCH RFC] allow some kernel filesystems to be mounted in a user namespace

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Message-ID: <20130716195002.GA23370@mail.hallyn.com>
Date:	Tue, 16 Jul 2013 19:50:03 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Serge Hallyn <serge.hallyn@...ntu.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] allow some kernel filesystems to be mounted in a
 user namespace

Quoting Al Viro (viro@...IV.linux.org.uk):
> On Tue, Jul 16, 2013 at 02:29:20PM -0500, Serge Hallyn wrote:
> > All the files will be owned by host root, so there's no security
> > concern in allowing this.
> 
> Files owned by root != very bad things can't be done by non-root.
> Especially for debugfs, which is very much a "don't even think about
> mounting that on a production box" thing...

I would prefer it not be mounted.  But near as I can tell there
should be no regression security-wise whether an unprivileged
user on the host has access to it, or whether a user in a
non-init user ns is allowed to mount it.  (Obviously I could very
well be wrong)

-serge
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