From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752583AbdLDU0F (ORCPT ); Mon, 4 Dec 2017 15:26:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:42332 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752035AbdLDU0E (ORCPT ); Mon, 4 Dec 2017 15:26:04 -0500 Date: Mon, 4 Dec 2017 21:25:53 +0100 From: Borislav Petkov To: Thomas Gleixner Cc: LKML , x86@kernel.org, Linus Torvalds , Andy Lutomirsky , Peter Zijlstra , Dave Hansen , Greg KH , keescook@google.com, hughd@google.com, Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Rik van Riel , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , aliguori@amazon.com, Will Deacon , daniel.gruss@iaik.tugraz.at, Kees Cook Subject: Re: [patch 23/60] x86/entry/64: Make cpu_entry_area.tss read-only Message-ID: <20171204202552.rnadiic5dxvwt4q3@pd.tnic> References: <20171204140706.296109558@linutronix.de> <20171204150606.733700132@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171204150606.733700132@linutronix.de> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 04, 2017 at 03:07:29PM +0100, Thomas Gleixner wrote: > From: Andy Lutomirski > > The TSS is a fairly juicy target for exploits, and, now that the TSS > is in the cpu_entry_area, it's no longer protected by kASLR. Make it > read-only on x86_64. > > On x86_32, it can't be RO because it's written by the CPU during task > switches, and we use a task gate for double faults. I'd also be > nervous about errata if we tried to make it RO even on configurations > without double fault handling. > > [ tglx: AMD confirmed that there is no problem on 64bit with TSS RO. So > it's probably safe to assume that it's a non issue, though Intel > might have been creative in that area. Still waiting for > confirmation. ] > > Signed-off-by: Andy Lutomirski > Signed-off-by: Thomas Gleixner > Cc: Kees Cook > Cc: Peter Zijlstra > Cc: Brian Gerst > Cc: David Laight > Cc: Borislav Petkov > Link: https://lkml.kernel.org/r/7d2f65f86a46e3489ba996932554485c3d345632.1512109321.git.luto@kernel.org > > --- > arch/x86/entry/entry_32.S | 4 ++-- > arch/x86/entry/entry_64.S | 8 ++++---- > arch/x86/include/asm/fixmap.h | 13 +++++++++---- > arch/x86/include/asm/processor.h | 17 ++++++++--------- > arch/x86/include/asm/switch_to.h | 4 ++-- > arch/x86/include/asm/thread_info.h | 2 +- > arch/x86/kernel/asm-offsets.c | 5 ++--- > arch/x86/kernel/asm-offsets_32.c | 4 ++-- > arch/x86/kernel/cpu/common.c | 29 +++++++++++++++++++---------- > arch/x86/kernel/ioport.c | 2 +- > arch/x86/kernel/process.c | 6 +++--- > arch/x86/kernel/process_32.c | 2 +- > arch/x86/kernel/process_64.c | 2 +- > arch/x86/kernel/traps.c | 4 ++-- > arch/x86/lib/delay.c | 4 ++-- > arch/x86/xen/enlighten_pv.c | 2 +- > 16 files changed, 60 insertions(+), 48 deletions(-) Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --