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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 1206EC43441 for ; Tue, 13 Nov 2018 18:33:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5032223C8 for ; Tue, 13 Nov 2018 18:33:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5032223C8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-integrity-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726721AbeKNEdH (ORCPT ); Tue, 13 Nov 2018 23:33:07 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:32760 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726932AbeKNEdH (ORCPT ); Tue, 13 Nov 2018 23:33:07 -0500 Received: from LHREML713-CAH.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id E9C733EB549FB; Tue, 13 Nov 2018 18:33:45 +0000 (GMT) Received: from [10.202.210.149] (10.202.210.149) by smtpsuk.huawei.com (10.201.108.36) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 13 Nov 2018 18:33:43 +0000 Subject: Re: [PATCH 10/17] prmem: documentation From: Igor Stoppa To: Andy Lutomirski , Nadav Amit CC: Igor Stoppa , Kees Cook , Peter Zijlstra , Mimi Zohar , Matthew Wilcox , Dave Chinner , James Morris , Michal Hocko , "Kernel Hardening" , linux-integrity , LSM List , Dave Hansen , Jonathan Corbet , Laura Abbott , Randy Dunlap , Mike Rapoport , "open list:DOCUMENTATION" , LKML , "Thomas Gleixner" References: <20181023213504.28905-1-igor.stoppa@huawei.com> <20181023213504.28905-11-igor.stoppa@huawei.com> <20181026092609.GB3159@worktop.c.hoisthospitality.com> <20181028183126.GB744@hirez.programming.kicks-ass.net> <40cd77ce-f234-3213-f3cb-0c3137c5e201@gmail.com> <20181030152641.GE8177@hirez.programming.kicks-ass.net> <0A7AFB50-9ADE-4E12-B541-EC7839223B65@amacapital.net> <6f60afc9-0fed-7f95-a11a-9a2eef33094c@gmail.com> <386C0CB1-C4B1-43E2-A754-DA8DBE4FB3CB@gmail.com> <9373ccf0-f51b-4bfa-2b16-e03ebf3c670d@huawei.com> Message-ID: <2e52e103-15d0-0c26-275f-894dfd07e8ec@huawei.com> Date: Tue, 13 Nov 2018 20:33:41 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <9373ccf0-f51b-4bfa-2b16-e03ebf3c670d@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.210.149] X-CFilter-Loop: Reflected Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org I forgot one sentence :-( On 13/11/2018 20:31, Igor Stoppa wrote: > On 13/11/2018 19:47, Andy Lutomirski wrote: > >> For general rare-writish stuff, I don't think we want IRQs running >> with them mapped anywhere for write. For AVC and IMA, I'm less sure. > > Why would these be less sensitive? > > But I see a big difference between my initial implementation and this one. > > In my case, by using a shared mapping, visible to all cores, freezing > the core that is performing the write would have exposed the writable > mapping to a potential attack run from another core. > > If the mapping is private to the core performing the write, even if it > is frozen, it's much harder to figure out what it had mapped and where, > from another core. > > To access that mapping, the attack should be performed from the ISR, I > think. Unless the secondary mapping is also available to other cores, through the shared mm_struct ? -- igor