linux-kernel - Re: [PATCH] devpts: Make ptmx be owned by the userns owner instead of userns-local 0

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Date:	Mon, 14 Mar 2016 16:42:55 +0100
From:	Alexander Larsson <alexl@...hat.com>
To:	Andy Lutomirski <luto@...nel.org>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>,
	linux-kernel@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	gnome-os-list@...me.org,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	mclasen@...hat.com,
	Linux Containers <containers@...ts.linux-foundation.org>
Subject: Re: [PATCH] devpts: Make ptmx be owned by the userns owner instead
 of userns-local 0

On sön, 2016-03-13 at 22:06 -0700, Andy Lutomirski wrote:
> We used to have ptmx be owned by the inner uid and gid 0.  Change
> this: if the owner and group are both mapped but are not both 0,
> then use the owner instead.
> 
> For container-style namespaces (LXC, etc), this should have no
> effect -- UID 0 is will either be the owner or will be unmapped.
> 
> The important behavior change is for sandboxes: many sandboxes
> intentionally do not create an inner uid 0.  Without this patch,
> mounting devpts in such a sandbox is awkward.  With this patch, it
> will just work and ptmx will be owned by the namespace owner.
> 
> Cc: Alexander Larsson <alexl@...hat.com>
> Cc: mclasen@...hat.com
> Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
> Cc: Linux Containers <containers@...ts.linux-foundation.org>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>

Tested-by: Alexander Larsson <alexl@...hat.com>

Seems to work fine for me! Thanks!

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 Alexander Larsson                                            Red Hat, Inc 
       alexl@...hat.com            alexander.larsson@...il.com 
He's an uncontrollable voodoo librarian with a robot buddy named Sparky. 
She's a cynical winged journalist from the wrong side of the tracks. They 
fight crime!