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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 DC710ECDE43 for ; Fri, 19 Oct 2018 15:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF0C820658 for ; Fri, 19 Oct 2018 15:49:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF0C820658 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-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727650AbeJSX41 (ORCPT ); Fri, 19 Oct 2018 19:56:27 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:55252 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726935AbeJSX4Z (ORCPT ); Fri, 19 Oct 2018 19:56:25 -0400 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 BEAAAEBD; Fri, 19 Oct 2018 08:49:45 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8D6E03F71A; Fri, 19 Oct 2018 08:49:45 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id A4C1B1AE06FD; Fri, 19 Oct 2018 16:49:48 +0100 (BST) Date: Fri, 19 Oct 2018 16:49:48 +0100 From: Will Deacon To: Kees Cook Cc: Catalin Marinas , Kristina Martsenko , linux-arm-kernel , Mark Rutland , linux-arch , Andrew Jones , Jacob Bramley , Arnd Bergmann , Ard Biesheuvel , Marc Zyngier , Adam Wallis , "Suzuki K . Poulose" , Christoffer Dall , kvmarm@lists.cs.columbia.edu, Ramana Radhakrishnan , Amit Kachhap , Dave P Martin , LKML , Cyrill Gorcunov Subject: Re: [PATCH v5 07/17] arm64: add basic pointer authentication support Message-ID: <20181019154948.GD16771@arm.com> References: <20181005084754.20950-1-kristina.martsenko@arm.com> <20181005084754.20950-8-kristina.martsenko@arm.com> <20181019111542.6wrvjguirglzg7vg@mbp> <20181019112404.GD14246@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) 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 08:36:45AM -0700, Kees Cook wrote: > On Fri, Oct 19, 2018 at 4:24 AM, Will Deacon wrote: > > FWIW: I think we should be entertaining a prctl() interface to use a new > > key on a per-thread basis. Obviously, this would need to be used with care > > (e.g. you'd fork(); use the prctl() and then you'd better not return from > > the calling function!). > > > > Assuming we want this (Kees -- I was under the impression that everything in > > Android would end up with the same key otherwise?), then the question is > > do we want: > > > > - prctl() get/set operations for the key, or > > - prctl() set_random_key operation, or > > - both of the above? > > > > Part of the answer to that may lie in the requirements of CRIU, where I > > strongly suspect they need explicit get/set operations, although these > > could be gated on CONFIG_CHECKPOINT_RESTORE=y. > > Oh CRIU. Yikes. I'd like the get/set to be gated by the CONFIG, yes. > No reason to allow explicit access to the key (and selected algo) if > we don't have to. Makes sense. > As for per-thread or not, having a "pick a new key now" prctl() sounds > good, but I'd like to have an eye toward having it just be "automatic" > on clone(). I thought about that too, but we're out of clone() flags afaict and there's no arch hook in there. We could add yet another clone syscall, but yuck (and I reckon viro would kill us). Or are you saying that we could infer the behaviour from the existing set of flags? Will