linux-kernel - Re: plan9 semantics on Linux

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Date:   Wed, 14 Feb 2018 15:03:55 +0100
From:   Enrico Weigelt <lkml@...ux.net>
To:     Richard Weinberger <richard@...ma-star.at>,
        Aleksa Sarai <asarai@...e.de>
Cc:     Linux Containers <containers@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: plan9 semantics on Linux - mount namespaces

On 14.02.2018 13:53, Richard Weinberger wrote:

> It does what you ask it for. > Also see the --setgroups switch.> AFAICT --setgroups=deny is the new 
default, then your command line should just> work. Maybe your unshare 
tool is too old.
Also doesn't help:

daemon@...habox:~ unshare -U -r --setgroups=deny
unshare: can't open '/proc/self/setgroups': Permission denied

>> What I'd like to achieve is that processes can manipulate their private >> namespace at will and mount other filesystems (primarily 9p and 
fuse).>>>> For that, I need to get rid of setuid (and per-file caps) for 
these>> private namespaces.>
> This is exactly why we have the user namespace.
> In the user namespace you can create your own mount namespace and do (almost)
> whatever you want.

What's the exact relation between user and mnt namespace ?
Why do I need an own user ns for private mnt ns ? (except for the suid
bit, which I wanna get rid of anyways).


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@...ux.net -- +49-151-27565287