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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 299CAECDE43 for ; Fri, 19 Oct 2018 18:38:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCD2B21476 for ; Fri, 19 Oct 2018 18:38:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jPpzrL5Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCD2B21476 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1727845AbeJTCqH (ORCPT ); Fri, 19 Oct 2018 22:46:07 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:43326 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727553AbeJTCqG (ORCPT ); Fri, 19 Oct 2018 22:46:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ksdlofJmQ1QwFGctRYs92LqBXcoHYFmBwsUtc8zGalo=; b=jPpzrL5QV1AjvEsP+t8JnYNIp +0p199GgYNX/jZQ/Uu+pZ5XZZwrDS2gk8lW0b60h4J9UWccCv5/xxwTsqaUWLJh/W+7i+VF9pGzsg E4rbjpxh9jvC+l9FzuTbYkj/fdNWCp2rUBvSM0wz8A2Fwpws5jcIDGPCqbGCw4iWPnitDH8tqfRZI 1lCPiiTZmHGMPSvP6v6Ub4gNcBvpALp3LlKEFzo+CfAm6wYGewnMYBLixLRftdd0v184TTqpNz0h1 zijka/obxactZiEgBb/Pr4sCeldcMb0Vn6VCJb0C8MRdHv2eNAss4dj/b0ClU9GPogp5XQ4L3P9SR 8vaBVv6wg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gDZfW-0007uR-Nh; Fri, 19 Oct 2018 18:38:43 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3443F20297B77; Fri, 19 Oct 2018 20:38:41 +0200 (CEST) Date: Fri, 19 Oct 2018 20:38:41 +0200 From: Peter Zijlstra To: Tim Chen Cc: Jiri Kosina , Thomas Gleixner , Tom Lendacky , Ingo Molnar , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [Patch v3 00/13] Provide process property based options to enable Spectre v2 userspace-userspace protection Message-ID: <20181019183841.GB31016@hirez.programming.kicks-ass.net> References: <20181019075740.GY3121@hirez.programming.kicks-ass.net> <591b320f-b3b0-278f-cde9-71a14b5e4d87@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <591b320f-b3b0-278f-cde9-71a14b5e4d87@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 19, 2018 at 09:43:35AM -0700, Tim Chen wrote: > On 10/19/2018 12:57 AM, Peter Zijlstra wrote: > > On Wed, Oct 17, 2018 at 10:59:28AM -0700, Tim Chen wrote: > >> Application to application exploit is in general difficult due to address > >> space layout randomization in applications and the need to know an > > > > Does the BTB attack on KASLR not work for userspace? > > > > With KASLR, you can probe the kernel mapped and unmapped > addresses with side channels like TLB and infer the kernel mapping > offsets much more easily, as kernel is in the same address > space as the attack process. It is a lot harder to do > such probing from another process that doesn't share the > same page tables. I said BTB; see: http://www.cs.binghamton.edu/~dima/micro16.pdf >From what I understood, local ASLR (of any kind) is a pipe dream.