From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758084Ab1FFVyg (ORCPT ); Mon, 6 Jun 2011 17:54:36 -0400 Received: from r00tworld.com ([212.85.137.150]:38471 "EHLO r00tworld.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757845Ab1FFVyf (ORCPT ); Mon, 6 Jun 2011 17:54:35 -0400 From: pageexec@freemail.hu To: Linus Torvalds Date: Mon, 06 Jun 2011 23:53:09 +0200 MIME-Version: 1.0 Subject: Re: [PATCH v5 9/9] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule Reply-to: pageexec@freemail.hu CC: Andi Kleen , Andy Lutomirski , Ingo Molnar , x86@kernel.org, Thomas Gleixner , linux-kernel@vger.kernel.org, Jesper Juhl , Borislav Petkov , Andrew Morton , Arjan van de Ven , Jan Beulich , richard -rw- weinberger , Mikael Pettersson , Brian Gerst , Louis Rilling , Valdis.Kletnieks@vt.edu Message-ID: <4DED4C45.19293.146C9286@pageexec.freemail.hu> In-reply-to: References: , <4DED206E.20356.13C155EA@pageexec.freemail.hu>, X-mailer: Pegasus Mail for Windows (4.61) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.12 (r00tworld.com [212.85.137.150]); Mon, 06 Jun 2011 23:53:43 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7 Jun 2011 at 5:40, Linus Torvalds wrote: > On Tue, Jun 7, 2011 at 3:46 AM, wrote: > > > >> I'm happy with perhaps moving away from the fixed-address vdso, > > > > it's not about the vdso that has been mmap'ed and randomized for quite some > > time now. it's about the amd64 specific vsyscall page. > > Duh. What do you think that thing is? It's a special fixed-address > vdso. that we call the vsyscall page and not some random vdso thing, they're quite different, that's why there's this whole patch series, duh. > What I complain about in the patch series was (specifically) that I > think the naming sucks and (non-specifically) that the whole series is > annoying. > > The config name is misleading and pointlessly scary - the whole thing > is not in itself "unsafe", so calling it that is just wrong. if it's safe to have the vsyscall page at a fixed address, then you surely wouldn't object to have its replacement at a fixed address as well, would you? yes/no? (if it's a 'yes' then you'd better have some non-security arguments too ;) > We *definitely* don't want to name it in a way that makes some random > person just turn it off because it's scary, since the random person > *shouldn't* turn it off today. Comprende? actually you confused yourself and got it backwards. we want everyone sane who cares an iota about security to turn off the legacy/fixed address vsyscall as soon as possible else it's a pointless exercise. capito? > If we can replace the vsyscall page with a page fault or int3 or > whatever, and it's only used for the 'time()' system call, just do it. i agree fully, there's no real reason for a config option imho, i never had one in PaX and noone ever complained let alone noticed it (except perhaps for failed exploit attempts but that's by design).