linux-kernel - Re: [PATCH v4 2/2] procfs/tasks: add a simple per-task procfs hidepid= field

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Message-ID: <CAGXu5jKz5vo3NwKb_JmNyWDCP0izK=sxTL6Dx_KmYX=1NK+icA@mail.gmail.com>
Date:   Fri, 10 Feb 2017 15:44:50 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Djalal Harouni <tixxdz@...il.com>,
        Linux API <linux-api@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Lafcadio Wluiki <wluikil@...il.com>
Subject: Re: [PATCH v4 2/2] procfs/tasks: add a simple per-task procfs
 hidepid= field

On Wed, Jan 18, 2017 at 3:35 PM, Andy Lutomirski <luto@...capital.net> wrote:
> On Wed, Jan 18, 2017 at 2:50 PM, Djalal Harouni <tixxdz@...il.com> wrote:
>> Andy I don't follow here, no_new_privs is never cleared right ? I
>> can't see the corresponding clear bit code for it.
>
> I believe that unsharing userns clears no_new_privs.

Seriously? That's kind of ... weird. I mean, I guess you're
priv-confined in a way, but that seems fragile.

-Kees

-- 
Kees Cook
Pixel Security