linux-kernel - Re: [PATCH v2] xattr: Enable security.capability in user namespaces

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Message-ID: <alpine.LRH.2.20.1707181659030.5209@namei.org>
Date:   Tue, 18 Jul 2017 17:01:36 +1000 (AEST)
From:   James Morris <jmorris@...ei.org>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.com>
cc:     "Theodore Ts'o" <tytso@....edu>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        containers@...ts.linux-foundation.org, lkp@...org,
        linux-kernel@...r.kernel.org, zohar@...ux.vnet.ibm.com,
        tycho@...ker.com, James.Bottomley@...senPartnership.com,
        vgoyal@...hat.com, christian.brauner@...lbox.org,
        amir73il@...il.com, linux-security-module@...r.kernel.org,
        casey@...aufler-ca.com
Subject: Re: [PATCH v2] xattr: Enable security.capability in user
 namespaces

On Thu, 13 Jul 2017, Stefan Berger wrote:

> A file shared by 2 containers, one mapping root to uid=1000, the other mapping
> root to uid=2000, will show these two xattrs on the host (init_user_ns) once
> these containers set xattrs on that file.

I may be missing something here, but what happens when say the uid=2000 
container and associated user is deleted from the system, then another is 
created with the same uid?

Won't this mean that you have unexpected capabilities turning up in the 
new container?

-- 
James Morris
<jmorris@...ei.org>