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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B1F9C4332F for ; Wed, 9 Feb 2022 05:27:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233488AbiBIFYe (ORCPT ); Wed, 9 Feb 2022 00:24:34 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:45674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232786AbiBIFSp (ORCPT ); Wed, 9 Feb 2022 00:18:45 -0500 X-Greylist: delayed 10646 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 08 Feb 2022 21:18:48 PST Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::225]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 202FFC03FEEE for ; Tue, 8 Feb 2022 21:18:47 -0800 (PST) Received: (Authenticated sender: joao@overdrivepizza.com) by mail.gandi.net (Postfix) with ESMTPA id 5123B1C0002; Wed, 9 Feb 2022 05:18:44 +0000 (UTC) MIME-Version: 1.0 Date: Tue, 08 Feb 2022 21:18:44 -0800 From: Joao Moreira To: Kees Cook Cc: Peter Zijlstra , x86@kernel.org, hjl.tools@gmail.com, jpoimboe@redhat.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, samitolvanen@google.com, llvm@lists.linux.dev Subject: Re: [RFC][PATCH 6/6] objtool: Add IBT validation / fixups In-Reply-To: <202202082003.FA77867@keescook> References: <20211122170301.764232470@infradead.org> <20211122170805.338489412@infradead.org> <6ebb0ab131c522f20c094294d49091fc@overdrivepizza.com> <202202081541.900F9E1B@keescook> <202202082003.FA77867@keescook> Message-ID: <9ea50c51ee8db366430c9dc697a83923@overdrivepizza.com> X-Sender: joao@overdrivepizza.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Ah, excellent, thanks for the pointers. There's also this in the works: > https://reviews.llvm.org/D119296 (a new CFI mode, designed to play nice > to objtool, IBT, etc.) Oh, great! Thanks for pointing it out. I guess I saw something with a similar name before ;) https://www.blackhat.com/docs/asia-17/materials/asia-17-Moreira-Drop-The-Rop-Fine-Grained-Control-Flow-Integrity-For-The-Linux-Kernel.pdf Jokes aside (and perhaps questions more targeted to Sami), from a diagonal look it seems that this follows the good old tag approach proposed by PaX/grsecurity, right? If this is the case, should I assume it could also benefit from features like -mibt-seal? Also are you considering that perhaps we can use alternatives to flip different CFI instrumentation as suggested by PeterZ in another thread? Tks, Joao