linux-kernel - Re: [RFC PATCH] cgroup namespaces: add a 'nsroot=' mountinfo field

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Message-ID: <20160413185033.GH3676@htj.duckdns.org>
Date:	Wed, 13 Apr 2016 14:50:33 -0400
From:	Tejun Heo <tj@...nel.org>
To:	"Serge E. Hallyn" <serge@...lyn.com>
Cc:	linux-api@...r.kernel.org, adityakali@...gle.com,
	Linux Containers <containers@...ts.osdl.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	cgroups@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] cgroup namespaces: add a 'nsroot=' mountinfo field

Hello, Serge.

On Wed, Apr 13, 2016 at 01:46:39PM -0500, Serge E. Hallyn wrote:
> It's not a leak of any information we're trying to hide.  I realize
> something like 8 years have passed, but I still basically go by the
> ksummit guidance that containers are ok but the kernel's first priority
> is to facilitate containers but not trick containers into thinking
> they're not containerized.  So long as the container is properly set
> up, I don't think there's anything the workload could do with the
> nsroot= info other than *know* that it is in a ns cgroup.
> 
> If we did change that guidance, there's a slew of proc info that we
> could better virtualize :)

I see.  I'm just wondering because the information here seems a bit
gratuituous.  Isn't the only thing necessary telling whether the root
is bind mounted or namescoped?  Wouldn't simple "nsroot" work for that
purpose?

Thanks.

-- 
tejun