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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D575EC2D0A3 for ; Thu, 12 Nov 2020 12:55:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7185E21D91 for ; Thu, 12 Nov 2020 12:55:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727916AbgKLMzA (ORCPT ); Thu, 12 Nov 2020 07:55:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:41382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727223AbgKLMzA (ORCPT ); Thu, 12 Nov 2020 07:55:00 -0500 Received: from gaia (unknown [2.26.170.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B5E4521D7F; Thu, 12 Nov 2020 12:54:56 +0000 (UTC) Date: Thu, 12 Nov 2020 12:54:54 +0000 From: Catalin Marinas To: Marco Elver Cc: Andrey Konovalov , Dmitry Vyukov , Alexander Potapenko , Will Deacon , Vincenzo Frascino , Evgenii Stepanov , Andrey Ryabinin , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev , Linux ARM , Linux Memory Management List , LKML Subject: Re: [PATCH v2 11/20] kasan: add and integrate kasan boot parameters Message-ID: <20201112125453.GM29613@gaia> References: <20201112113541.GK29613@gaia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 12, 2020 at 12:53:58PM +0100, Marco Elver wrote: > On Thu, 12 Nov 2020 at 12:35, Catalin Marinas wrote: > > > > On Tue, Nov 10, 2020 at 11:20:15PM +0100, Andrey Konovalov wrote: > > > Hardware tag-based KASAN mode is intended to eventually be used in > > > production as a security mitigation. Therefore there's a need for finer > > > control over KASAN features and for an existence of a kill switch. > > > > > > This change adds a few boot parameters for hardware tag-based KASAN that > > > allow to disable or otherwise control particular KASAN features. > > > > > > The features that can be controlled are: > > > > > > 1. Whether KASAN is enabled at all. > > > 2. Whether KASAN collects and saves alloc/free stacks. > > > 3. Whether KASAN panics on a detected bug or not. > > > > > > With this change a new boot parameter kasan.mode allows to choose one of > > > three main modes: > > > > > > - kasan.mode=off - KASAN is disabled, no tag checks are performed > > > - kasan.mode=prod - only essential production features are enabled > > > - kasan.mode=full - all KASAN features are enabled > > > > Alternative naming if we want to avoid "production" (in case someone > > considers MTE to be expensive in a production system): > > > > - kasan.mode=off > > - kasan.mode=on > > - kasan.mode=debug > > I believe this was what it was in RFC, and we had a long discussion on > what might be the most intuitive options. Since KASAN is still a > debugging tool for the most part, an "on" mode might imply we get all > the debugging facilities of regular KASAN. However, this is not the > case and misleading. Hence, we decided to be more explicit and avoid > "on". Even better, kasan.mode=fast ;). -- Catalin