linux-kernel - Re: plan9 semantics on Linux

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Message-ID: <e924b563-44c6-d678-a6cc-1181f4b820d5@metux.net>
Date:   Wed, 14 Feb 2018 18:21:12 +0100
From:   Enrico Weigelt <lkml@...ux.net>
To:     Richard Weinberger <richard@...ma-star.at>
Cc:     Aleksa Sarai <asarai@...e.de>,
        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 16:17, Richard Weinberger wrote:

>  From taking a *very* quick look into busybox source, I suspect this should fix
> it:
> 
> diff --git a/util-linux/unshare.c b/util-linux/unshare.c
> index 875e3f86e304..3f59cf4d27c2 100644
> --- a/util-linux/unshare.c
> +++ b/util-linux/unshare.c
> @@ -350,9 +350,9 @@ int unshare_main(int argc UNUSED_PARAM, char **argv)
>   		 * in that user namespace.
>   		 */
>   		xopen_xwrite_close(PATH_PROC_SETGROUPS, "deny");
> -		sprintf(uidmap_buf, "%u 0 1", (unsigned)reuid);
> +		sprintf(uidmap_buf, "0 %u 1", (unsigned)reuid);
>   		xopen_xwrite_close(PATH_PROC_UIDMAP, uidmap_buf);
> -		sprintf(uidmap_buf, "%u 0 1", (unsigned)regid);
> +		sprintf(uidmap_buf, "0 %u 1", (unsigned)regid);
>   		xopen_xwrite_close(PATH_PROC_GIDMAP, uidmap_buf);
>   	} else
>   	if (setgrp_str) {
> 

hmm, now it works, but only when strace'ing it.
that's really strange.

But still I wonder whether user_ns really solves my problem, as I don't
want to create sandboxed users, but only private namespaces just like
on Plan9.


--mtx

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