From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753103AbbK3HBw (ORCPT ); Mon, 30 Nov 2015 02:01:52 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:57033 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751788AbbK3HBt (ORCPT ); Mon, 30 Nov 2015 02:01:49 -0500 Date: Mon, 30 Nov 2015 08:01:36 +0100 From: Willy Tarreau To: Ben Hutchings Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Konstantin Khlebnikov , Naoya Horiguchi , Mark Williamson , Andrew Morton , Linus Torvalds Subject: Re: [PATCH 2.6.32 19/38] [PATCH 19/38] pagemap: hide physical addresses from non-privileged users Message-ID: <20151130070136.GB31694@1wt.eu> References: <20151129214703.685445143@1wt.eu> <1448848462.1990.44.camel@decadent.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1448848462.1990.44.camel@decadent.org.uk> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 30, 2015 at 01:54:22AM +0000, Ben Hutchings wrote: > On Sun, 2015-11-29 at 22:47 +0100, Willy Tarreau wrote: > This is wrong; see > . Damned, and I now remember this discussion. The worst thing is that I purposely booted a machine to test the fix and was happy with it, I forgot this point :-( > For 2.6.32 perhaps you could retain the capability check at open time > but store the result in private state for use at read time. I'll see if it is possible to opencode security_capable() with 2.6.32's infrastructure, and how far this brings us. Or maybe we should even drop this one completely and leave pagemap readable only for superuser on 2.6.32, it doesn't seem to be that big of a deal either. > The ptrace check presumably should also be done at open time, as was > implemented upstream in: > > commit a06db751c321546e5563041956a57613259c6720 > Author: Konstantin Khlebnikov > Date:   Tue Sep 8 14:59:59 2015 -0700 > >     pagemap: check permissions and capabilities at open time > > But that wasn't cc'd to stable and hasn't been applied to any stable > branch (yet). I really prefer to avoid fixing things that are not in more recent branches (especially upgrade candidates for 2.6.32 like yours). Thanks! Willy