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=-3.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 C6B91C282DD for ; Thu, 23 May 2019 15:08:34 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E39F2175B for ; Thu, 23 May 2019 15:08:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lgV8AwVl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E39F2175B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=lsCZdwiSsQpjiMm1SFDyRDaETvsnnjmFzEWyT6IhLEY=; b=lgV8AwVlUDGUaJ 8B6nuY3T7P5R780+LFtZhgE06ZygrY/4hsyx9QH98NXh+X2fPbl05jjuZByDsXQ16ZVR2XMGYJx6J GxlNlIcDHGN5ekcQApnQ0cqECIMVisqknFTUJZv/eszekznLzYYV9P4B/1xOVxcNk4E0kqIcTpigv GoXFlC3/q6hQuvqdQuSEBfG5VqCqo/U9v24AkoZQWTTowp6PQ6UDuQL6CKIQsUZcFdSwT9AQxPjlR 1iskxMhXtHJz1JsyINrRkeNsTW7w9gcCUNxF2FJv3Qul3F5GaNAd7iD5uGASRxJ6YNWFPnvmBbI5L 4fmoYa0QMZenQ4TU6mxw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hTpKZ-0005Cz-0t; Thu, 23 May 2019 15:08:31 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hTpKV-0005CA-SG for linux-arm-kernel@lists.infradead.org; Thu, 23 May 2019 15:08:29 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C7E5C80D; Thu, 23 May 2019 08:08:26 -0700 (PDT) Received: from mbp (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B63863F690; Thu, 23 May 2019 08:08:20 -0700 (PDT) Date: Thu, 23 May 2019 16:08:14 +0100 From: Catalin Marinas To: Kees Cook Subject: Re: [PATCH v15 00/17] arm64: untag user pointers passed to the kernel Message-ID: <20190523150813.x4btg5zxa4gl5o4q@mbp> References: <20190517144931.GA56186@arrakis.emea.arm.com> <20190521182932.sm4vxweuwo5ermyd@mbp> <201905211633.6C0BF0C2@keescook> <20190522101110.m2stmpaj7seezveq@mbp> <201905221157.A9BAB1F296@keescook> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <201905221157.A9BAB1F296@keescook> User-Agent: NeoMutt/20170113 (1.7.2) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190523_080827_920818_EDBABC36 X-CRM114-Status: GOOD ( 14.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kvm@vger.kernel.org, Szabolcs Nagy , Will Deacon , dri-devel@lists.freedesktop.org, Linux Memory Management List , Khalid Aziz , "open list:KERNEL SELFTEST FRAMEWORK" , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, Dmitry Vyukov , Dave Martin , Evgenii Stepanov , linux-media@vger.kernel.org, Kevin Brodsky , Ruben Ayrapetyan , Andrey Konovalov , Ramana Radhakrishnan , Alex Williamson , Yishai Hadas , Mauro Carvalho Chehab , Linux ARM , Kostya Serebryany , Greg Kroah-Hartman , Felix Kuehling , LKML , Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 22, 2019 at 12:21:27PM -0700, Kees Cook wrote: > If a process wants to not tag, that's also up to the allocator where > it can decide not to ask the kernel, and just not tag. Nothing breaks in > userspace if a process is NOT tagging and untagged_addr() exists or is > missing. This, I think, is the core way this doesn't trip over the > golden rule: an old system image will run fine (because it's not > tagging). A *new* system may encounter bugs with tagging because it's a > new feature: this is The Way Of Things. But we don't break old userspace > because old userspace isn't using tags. With this series and hwasan binaries, at some point in the future they will be considered "old userspace" and they do use pointer tags which expect to be ignored by both the hardware and the kernel. MTE breaks this assumption. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel