From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754849Ab3BZWIt (ORCPT ); Tue, 26 Feb 2013 17:08:49 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:56840 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751644Ab3BZWIs (ORCPT ); Tue, 26 Feb 2013 17:08:48 -0500 Date: Tue, 26 Feb 2013 09:24:41 -0800 From: Matt Helsley To: Kees Cook Cc: linux-kernel@vger.kernel.org, Evgeniy Polyakov , netdev@vger.kernel.org, Matt Helsley Subject: Re: [PATCH] proc connector: reject unprivileged listener bumps Message-ID: <20130226172441.GA6312@us.ibm.com> References: <20130226073225.GA15489@www.outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130226073225.GA15489@www.outflux.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13022622-9360-0000-0000-000011136C60 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 25, 2013 at 11:32:25PM -0800, Kees Cook wrote: > While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible > for an unprivileged user to turn off notifications for all listeners by > sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as > required for a multicast bind. > > Signed-off-by: Kees Cook > Cc: Evgeniy Polyakov > Cc: Matt Helsley > Cc: stable@vger.kernel.org > --- > drivers/connector/cn_proc.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c > index fce2000..1110478 100644 > --- a/drivers/connector/cn_proc.c > +++ b/drivers/connector/cn_proc.c > @@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, > (task_active_pid_ns(current) != &init_pid_ns)) > return; > > + /* Can only change if privileged. */ I think this comment doesn't tell us anything above and beyond the what capability check already tells us. I think you could improve it by noting that since the connector is multicast and not namespace-safe it's not yet appropriate to use ns_capable() here. Acked-by: Matt Helsley > + if (!capable(CAP_NET_ADMIN)) { > + err = EPERM; > + goto out; > + }