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 D20BEC43381 for ; Thu, 7 Mar 2019 15:59:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3A3F20652 for ; Thu, 7 Mar 2019 15:59:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726709AbfCGP7i (ORCPT ); Thu, 7 Mar 2019 10:59:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39252 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726285AbfCGP7h (ORCPT ); Thu, 7 Mar 2019 10:59:37 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BFE6236807; Thu, 7 Mar 2019 15:59:37 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-148.rdu2.redhat.com [10.10.121.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4859F5C1A1; Thu, 7 Mar 2019 15:59:33 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20190306235913.6631-3-matthewgarrett@google.com> References: <20190306235913.6631-3-matthewgarrett@google.com> <20190306235913.6631-1-matthewgarrett@google.com> To: Matthew Garrett Cc: dhowells@redhat.com, jmorris@namei.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 02/27] Add a SysRq option to lift kernel lockdown MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <15832.1551974371.1@warthog.procyon.org.uk> Date: Thu, 07 Mar 2019 15:59:31 +0000 Message-ID: <15833.1551974371@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 07 Mar 2019 15:59:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthew Garrett wrote: > + /* Ban synthetic events from some sysrq functionality */ > + if ((from == SYSRQ_FROM_PROC || from == SYSRQ_FROM_SYNTHETIC) && > + op_p->enable_mask & SYSRQ_DISABLE_USERSPACE) > + printk("This sysrq operation is disabled from userspace.\n"); > /* > * Should we check for enabled operations (/proc/sysrq-trigger > * should not) and is the invoked operation enabled? > */ > - if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { > + if (from == SYSRQ_FROM_KERNEL || sysrq_on_mask(op_p->enable_mask)) { There's some missing logic here. Probably an else is missing, but it seems more than that. David