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From: Andy Lutomirski <luto@amacapital.net>
Date: Tue, 29 Apr 2014 17:33:41 -0700
Message-ID: <CALCETrU4KXbwvfgtBo=fZ-=DGzgTkEVP0G=FhvJhdoo=+K1g6g@mail.gmail.com>
Subject: Re: ioctl CAP_LINUX_IMMUTABLE is checked in the wrong namespace
To: "Theodore Ts'o" <tytso@mit.edu>, Serge Hallyn <serge.hallyn@ubuntu.com>,
        Andy Lutomirski <luto@amacapital.net>, Marian Marinov <mm@1h.com>,
        Linux Containers <containers@lists.linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        lxc-devel <lxc-devel@lists.sourceforge.net>
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Sender: linux-kernel-owner@vger.kernel.org

On Tue, Apr 29, 2014 at 5:32 PM, Theodore Ts'o <tytso@mit.edu> wrote:
> On Wed, Apr 30, 2014 at 12:16:41AM +0000, Serge Hallyn wrote:
>> I forget the details, but there was another case where I wanted to
>> have the userns which 'owns' the whole fs available.  I guess we'd
>> have to check against that instead of using inode_capable.
>
> Yes, that sounds right.
>
> And *please* tell me that that under no circumstances can anyone other
> than root@init_user_ns is allowed to use mknod....

I haven't read the code, but I tried it the other day, and I got
-EPERM.  So we're okay for now.  (Well, other than the issue I just
sent to security@kernel.org, but that's not quite the same thing.)

--Andy
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