Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758225Ab1EaTgb (ORCPT ); Tue, 31 May 2011 15:36:31 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:34618 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758107Ab1EaTga (ORCPT ); Tue, 31 May 2011 15:36:30 -0400 Date: Tue, 31 May 2011 21:36:02 +0200 From: Ingo Molnar To: Andrew Lutomirski Cc: Andi Kleen , x86@kernel.org, Thomas Gleixner , linux-kernel@vger.kernel.org, Jesper Juhl , Borislav Petkov , Linus Torvalds , Andrew Morton , Arjan van de Ven , Jan Beulich , richard -rw- weinberger , Mikael Pettersson Subject: Re: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule Message-ID: <20110531193602.GA26535@elte.hu> References: <1660d1687db01852ec58bbf970e22868db367d53.1306851090.git.luto@mit.edu> <20110531183448.GA27166@one.firstfloor.org> <20110531192833.GA23458@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110531192833.GA23458@elte.hu> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 921 Lines: 25 * Ingo Molnar wrote: > [...] solution that filters the caller RIP at the generic syscall > entry point and checks RCX against the 'expected' SYSCALL > instruction address, which is the (per task) vdso-address + > constant-offset. Note that this solution would allow the vsyscall page to be 'filtered' to the 3 allowed system calls rather efficiently, via a second level check. This second check does not affect the fastpath, and it could be put behind a CONFIG_COMPAT_VSYSCALL deprecation define once glibc does not put vsyscall references anywhere - but we could even keep it around forever, as this way it's defanged permanently. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/