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Re: [PATCH v7 7/7] enable building user namespace with xfs

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH v7 7/7] enable building user namespace with xfs
From: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Date: Wed, 7 Aug 2013 14:59:30 +0000
Cc: Ben Myers <bpm@xxxxxxx>, Dwight Engen <dwight.engen@xxxxxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130731232852.GE7118@dastard>
References: <20130729230709.11033b2d@xxxxxxxxxx> <20130730234021.GR3111@xxxxxxx> <20130731002119.GR13468@dastard> <20130731132523.GS3111@xxxxxxx> <20130731232852.GE7118@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
Quoting Dave Chinner (david@xxxxxxxxxxxxx):
> On Wed, Jul 31, 2013 at 08:25:23AM -0500, Ben Myers wrote:
> > Hey,
> > 
> > On Wed, Jul 31, 2013 at 10:21:19AM +1000, Dave Chinner wrote:
> > > On Tue, Jul 30, 2013 at 06:40:21PM -0500, Ben Myers wrote:
> > > > On Mon, Jul 29, 2013 at 11:07:09PM -0400, Dwight Engen wrote:
> > > > > >From e6a9ee0cfa0ed40484f66bc1726dc19de36038b8 Mon Sep 17 00:00:00 
> > > > > >2001
> > > > > From: Dwight Engen <dwight.engen@xxxxxxxxxx>
> > > > > Date: Tue, 2 Jul 2013 09:52:54 -0400
> > > > > Subject: [PATCH 7/7] enable building user namespace with xfs
> > > > > 
> > > > > Signed-off-by: Dwight Engen <dwight.engen@xxxxxxxxxx>
> > > > 
> > > > Was there a patch running around to limit bulkstat to init_user_ns?  
> > > > Any other
> > > > items that needed to be addressed before applying this patch?
> > > 
> > > Bulkstat has a capable(CAP_SYS_ADMIN) check and therefore can only be
> > > executed in the init name space. Similarly, all the open-by-handle
> > > interfaces have the same capable() checks so they can only be
> > > executed int he init name space, too.
> > 
> > Gah.  I was under the impression that you could have a process with
> > CAP_SYS_ADMIN in a namespace other than init_user_ns.
> 
> Ben, until about a week and a half ago I was also working under that
> same understanding as you.  So don't feel bad about not knowing
> about this basic, fundamental rule because it is completely
> undocumented and it's not obvious to anyone reading the code until
> someone points it out....

It's actually all documented in new manpages like namespaces(7) and
user_namespaces(7).  Unfortunately those don't seem to have been released yet.

Michael, I don't see any git development/experimental git branch at
kernel.org/pub/scm/docs/man-pages - do you have those pages up
somewhere?

thanks,
-serge

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