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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_IN_DEF_DKIM_WL 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 4493DC43381 for ; Wed, 27 Mar 2019 16:55:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 148D4206C0 for ; Wed, 27 Mar 2019 16:55:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="M79gIw9H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbfC0Qzd (ORCPT ); Wed, 27 Mar 2019 12:55:33 -0400 Received: from mail-it1-f196.google.com ([209.85.166.196]:53289 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727234AbfC0Qzd (ORCPT ); Wed, 27 Mar 2019 12:55:33 -0400 Received: by mail-it1-f196.google.com with SMTP id y204so1247812itf.3 for ; Wed, 27 Mar 2019 09:55:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ZszyTtRF4sHiwangw3H/m8V0aWY+bOEBhByx7XP37/s=; b=M79gIw9HCV82g4XpuEVjztM1XAmvhjLbNndudce0CqkXhG+I7FgR26SMsImL8Tk5YV oqk85VHUtl2gamGGt1YkunwpjXEMTLk1zyLETfXdBI+TXY6tSoCHcF7GA9K3rq96rn5f X549QhcvFXGJPJzGh4dzRRiFLFB06EVnL6HXVCS525ZT3CiL3MYqPnqU/DZOjIYa6I49 L5iDwCOM9lntttsMy3QZAIKe29OzFJy+1HljawQM7p0FgD5hRBgWp9BGgSsfYzTl+D8M kXAaIag2gLCodOynS/QXTGVYZnZ5UASpNf83zotliL1TpPijAza6bWLjmbyAy0EMBDOj 6avg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ZszyTtRF4sHiwangw3H/m8V0aWY+bOEBhByx7XP37/s=; b=brvVDuM9Cj+wmgXeX2wR4XRl3/dhPaZ2T6ctIK6e4BWvlWVeSQRqpICyMevYPkWfYE 34f1/j0yRysfhrardenRStD8pdcxE9UwhLIWFHlyah2ukOxWc/UGxa1Q7vW5Bah6VIRS F46QK89b/qY6MjW8Oxcc8HpO6ti1iNhKEDtB4efWPEpTiFIwUFAqb6gZ1PrD7Kaek0jz 7geeaFabR6XiZilna/QGU7m6HdT9kKrqyQtF52j9TKBI9xwAY7qzmBdX+4Zl63DZC/YQ cZm23pMgwTZT7NiZZeUPAu89/PY50XS3nGHqoQrS7eNrKU9D1J/9WJTkXhVPwIg2J0tD Etfw== X-Gm-Message-State: APjAAAUSwy+Va+tk8v3+nrzWJJjZSJtGk9ZqBrdhd/uWPgkraNmopupW LrZOzSZTHwxCYK4q4z8QDNIEPHpurv0WF/yqD9anh/Wf8Br53w== X-Google-Smtp-Source: APXvYqzKVlIc5myKpqLCnzElqMwoj1ybJfgfjdPEZITuFjuuEXyvCtRUV9B8g9wo8X/E2fs/Yjr/8JnVF/d5oQXXME4= X-Received: by 2002:a24:2c48:: with SMTP id i69mr4469887iti.161.1553705732048; Wed, 27 Mar 2019 09:55:32 -0700 (PDT) MIME-Version: 1.0 References: <20190326182742.16950-1-matthewgarrett@google.com> <20190326182742.16950-20-matthewgarrett@google.com> <20190327115749.5770a102@gandalf.local.home> In-Reply-To: <20190327115749.5770a102@gandalf.local.home> From: Matthew Garrett Date: Wed, 27 Mar 2019 09:55:20 -0700 Message-ID: Subject: Re: [PATCH V31 19/25] x86/mmiotrace: Lock down the testmmiotrace module To: Steven Rostedt Cc: James Morris , LSM List , Linux Kernel Mailing List , David Howells , Linux API , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Wed, Mar 27, 2019 at 8:57 AM Steven Rostedt wrote: > > On Tue, 26 Mar 2019 11:27:35 -0700 > Matthew Garrett wrote: > > > From: David Howells > > > > The testmmiotrace module shouldn't be permitted when the kernel is locked > > down as it can be used to arbitrarily read and write MMIO space. This is > > a runtime check rather than buildtime in order to allow configurations > > where the same kernel may be run in both locked down or permissive modes > > depending on local policy. > > > > Acked-by: Steven Rostedt (VMware) > > I'm curious. Should there be a mode to lockdown the tracefs directory > too? As that can expose addresses. That sounds like a reasonable thing to do in the confidentiality mode, I don't think it'd be necessary in the integrity mode.