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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 51693C433DF for ; Wed, 22 Jul 2020 19:56:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CB4E20825 for ; Wed, 22 Jul 2020 19:56:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732552AbgGVT4Q (ORCPT ); Wed, 22 Jul 2020 15:56:16 -0400 Received: from mga02.intel.com ([134.134.136.20]:40083 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726525AbgGVT4Q (ORCPT ); Wed, 22 Jul 2020 15:56:16 -0400 IronPort-SDR: i8mlJNivRn3tjIKkhlmSz3egI/kbAd+e6Yd/SpzDpmUZJlQFyM0cBneI7DseMjG+xGesO0tPx6 2lR+219e+ccA== X-IronPort-AV: E=McAfee;i="6000,8403,9690"; a="138501878" X-IronPort-AV: E=Sophos;i="5.75,383,1589266800"; d="scan'208";a="138501878" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2020 12:56:15 -0700 IronPort-SDR: dp01G1YgXUZz1OxqW8lljzi0D0OzzYTa7bKaJ2Mo0oDFhpSjcg2Jrf8enws2LkIq4FTbEBDlrT fdd7QdYdtahw== X-IronPort-AV: E=Sophos;i="5.75,383,1589266800"; d="scan'208";a="362820651" Received: from kcaccard-mobl.amr.corp.intel.com (HELO kcaccard-mobl1.jf.intel.com) ([10.212.14.158]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2020 12:56:13 -0700 Message-ID: <301c7fb7d22ad6ef97856b421873e32c2239d412.camel@linux.intel.com> Subject: Re: [PATCH v4 00/10] Function Granular KASLR From: Kristen Carlson Accardi To: Kees Cook , Josh Poimboeuf Cc: Miroslav Benes , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arjan@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, live-patching@vger.kernel.org Date: Wed, 22 Jul 2020 12:56:10 -0700 In-Reply-To: <202007221241.EBC2215A@keescook> References: <20200717170008.5949-1-kristen@linux.intel.com> <202007220738.72F26D2480@keescook> <20200722160730.cfhcj4eisglnzolr@treble> <202007221241.EBC2215A@keescook> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: live-patching-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Wed, 2020-07-22 at 12:42 -0700, Kees Cook wrote: > On Wed, Jul 22, 2020 at 11:07:30AM -0500, Josh Poimboeuf wrote: > > On Wed, Jul 22, 2020 at 07:39:55AM -0700, Kees Cook wrote: > > > On Wed, Jul 22, 2020 at 11:27:30AM +0200, Miroslav Benes wrote: > > > > Let me CC live-patching ML, because from a quick glance this is > > > > something > > > > which could impact live patching code. At least it invalidates > > > > assumptions > > > > which "sympos" is based on. > > > > > > In a quick skim, it looks like the symbol resolution is using > > > kallsyms_on_each_symbol(), so I think this is safe? What's a good > > > selftest for live-patching? > > > > The problem is duplicate symbols. If there are two static > > functions > > named 'foo' then livepatch needs a way to distinguish them. > > > > Our current approach to that problem is "sympos". We rely on the > > fact > > that the second foo() always comes after the first one in the > > symbol > > list and kallsyms. So they're referred to as foo,1 and foo,2. > > Ah. Fun. In that case, perhaps the LTO series has some solutions. I > think builds with LTO end up renaming duplicate symbols like that, so > it'll be back to being unique. > Well, glad to hear there might be some precendence for how to solve this, as I wasn't able to think of something reasonable off the top of my head. Are you speaking of the Clang LTO series? https://lore.kernel.org/lkml/20200624203200.78870-1-samitolvanen@google.com/