From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751374AbdEBTCe (ORCPT ); Tue, 2 May 2017 15:02:34 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50437 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927AbdEBTCc (ORCPT ); Tue, 2 May 2017 15:02:32 -0400 Subject: Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set From: Mimi Zohar To: David Howells Cc: Dave Young , linux-kernel@vger.kernel.org, Matthew Garrett , linux-efi@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, Chun-Yi Lee , gregkh@linuxfoundation.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, matthew.garrett@nebula.com Date: Tue, 02 May 2017 15:01:22 -0400 In-Reply-To: <13679.1491830392@warthog.procyon.org.uk> References: <1491568577.4184.97.camel@linux.vnet.ibm.com> <1491551180.4184.50.camel@linux.vnet.ibm.com> <1491536950.4184.10.camel@linux.vnet.ibm.com> <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> <149142335441.5101.2294976563846442575.stgit@warthog.procyon.org.uk> <20170407030545.GA4296@dhcp-128-65.nay.redhat.com> <21572.1491548994@warthog.procyon.org.uk> <27362.1491556638@warthog.procyon.org.uk> <13679.1491830392@warthog.procyon.org.uk> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-MML: disable x-cbid: 17050219-0048-0000-0000-00000226F674 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17050219-0049-0000-0000-000047D4E93A Message-Id: <1493751682.3680.11.camel@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-02_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705020098 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, On Mon, 2017-04-10 at 14:19 +0100, David Howells wrote: > Mimi Zohar wrote: > > > From an IMA perspective, either a file hash or signature are valid, > > but for this usage it must be a signature. > > Not necessarily. If IMA can guarantee that a module is the same based on its > hash rather than on a key, I would've thought that should be fine. File hashes can be modified on the running system, so they're normally used, in conjunction with EVM, to detect off line modification of mutable files and prevent their usage. These patches https://lkml.org/lkml/2017/5/2/465 should provide some of the missing functionality. Mimi