From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54C39ECDFD0 for ; Fri, 14 Sep 2018 11:05:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0292B20881 for ; Fri, 14 Sep 2018 11:05:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0292B20881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727754AbeINQT3 (ORCPT ); Fri, 14 Sep 2018 12:19:29 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:47541 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726872AbeINQT3 (ORCPT ); Fri, 14 Sep 2018 12:19:29 -0400 Received: from p4fea45ac.dip0.t-ipconnect.de ([79.234.69.172] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1g0luR-0002ck-R2; Fri, 14 Sep 2018 13:05:11 +0200 Date: Fri, 14 Sep 2018 13:05:10 +0200 (CEST) From: Thomas Gleixner To: Jiri Kosina cc: "Schaufler, Casey" , Ingo Molnar , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , "Woodhouse, David" , Andi Kleen , Tim Chen , "linux-kernel@vger.kernel.org" , "x86@kernel.org" Subject: RE: [PATCH v6 1/3] x86/speculation: apply IBPB more strictly to avoid cross-process data leak In-Reply-To: Message-ID: References: <99FC4B6EFCEFD44486C35F4C281DC6732144BFBC@ORSMSX107.amr.corp.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 14 Sep 2018, Jiri Kosina wrote: > On Thu, 13 Sep 2018, Schaufler, Casey wrote: > > > > - return security_ptrace_access_check(task, mode); > > > + if (!(mode & PTRACE_MODE_NOACCESS_CHK)) > > > + return security_ptrace_access_check(task, mode); > > > + return 0; > > > > Because PTRACE_MODE_IBPB includes PTRACE_MODE_NOAUDIT you > > shouldn't need this change. > > That is true, but that's not my concern here. > > security_ptrace_access_check() -> call_int_hook() -> P->hook.FUNC(). > > If it's somehow guaranteed that all functions called this ways are fine to > be called from scheduler context (wrt. locks), then it's all fine and I'll > happily drop that check. > > Is it guaranteed? The related question is whether it is guaranteed for backports. We don't want to end up with a separate hell there. Thanks, tglx