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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 C1DBAC433DF for ; Wed, 5 Aug 2020 17:19:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9ED12177B for ; Wed, 5 Aug 2020 17:19:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728268AbgHERTe (ORCPT ); Wed, 5 Aug 2020 13:19:34 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:55616 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728329AbgHERSR (ORCPT ); Wed, 5 Aug 2020 13:18:17 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 075CWTU4055929; Wed, 5 Aug 2020 08:57:09 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 32qrujyvus-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 05 Aug 2020 08:57:08 -0400 Received: from m0098404.ppops.net (m0098404.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 075CWVpf056073; Wed, 5 Aug 2020 08:57:08 -0400 Received: from ppma06fra.de.ibm.com (48.49.7a9f.ip4.static.sl-reverse.com [159.122.73.72]) by mx0a-001b2d01.pphosted.com with ESMTP id 32qrujyvu3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 05 Aug 2020 08:57:08 -0400 Received: from pps.filterd (ppma06fra.de.ibm.com [127.0.0.1]) by ppma06fra.de.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 075Cv6Md006291; Wed, 5 Aug 2020 12:57:06 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma06fra.de.ibm.com with ESMTP id 32mynhanre-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 05 Aug 2020 12:57:05 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 075Cv3Rx61080026 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 5 Aug 2020 12:57:03 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C005AA4040; Wed, 5 Aug 2020 12:57:03 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CE60BA4053; Wed, 5 Aug 2020 12:57:00 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com (unknown [9.160.95.205]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 5 Aug 2020 12:57:00 +0000 (GMT) Message-ID: <31d00876438d2652890ab8bf6ba2e80f554ca7a4.camel@linux.ibm.com> Subject: Re: [PATCH v6 1/4] IMA: Add func to measure LSM state and policy From: Mimi Zohar To: Stephen Smalley , Lakshmi Ramasubramanian , casey@schaufler-ca.com Cc: tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 05 Aug 2020 08:56:59 -0400 In-Reply-To: References: <20200805004331.20652-1-nramas@linux.microsoft.com> <20200805004331.20652-2-nramas@linux.microsoft.com> <4b9d2715d3ef3c8f915ef03867cfb1a39c0abc54.camel@linux.ibm.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.28.5 (3.28.5-12.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-05_09:2020-08-03,2020-08-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 bulkscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 spamscore=0 mlxscore=0 mlxlogscore=999 clxscore=1015 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008050102 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Wed, 2020-08-05 at 08:46 -0400, Stephen Smalley wrote: > On 8/4/20 11:25 PM, Mimi Zohar wrote: > > > Hi Lakshmi, > > > > There's still a number of other patch sets needing to be reviewed > > before my getting to this one. The comment below is from a high level. > > > > On Tue, 2020-08-04 at 17:43 -0700, Lakshmi Ramasubramanian wrote: > > > Critical data structures of security modules need to be measured to > > > enable an attestation service to verify if the configuration and > > > policies for the security modules have been setup correctly and > > > that they haven't been tampered with at runtime. A new IMA policy is > > > required for handling this measurement. > > > > > > Define two new IMA policy func namely LSM_STATE and LSM_POLICY to > > > measure the state and the policy provided by the security modules. > > > Update ima_match_rules() and ima_validate_rule() to check for > > > the new func and ima_parse_rule() to handle the new func. > > I can understand wanting to measure the in kernel LSM memory state to > > make sure it hasn't changed, but policies are stored as files. Buffer > > measurements should be limited to those things that are not files. > > > > Changing how data is passed to the kernel has been happening for a > > while. For example, instead of passing the kernel module or kernel > > image in a buffer, the new syscalls - finit_module, kexec_file_load - > > pass an open file descriptor. Similarly, instead of loading the IMA > > policy data, a pathname may be provided. > > > > Pre and post security hooks already exist for reading files. Instead > > of adding IMA support for measuring the policy file data, update the > > mechanism for loading the LSM policy. Then not only will you be able > > to measure the policy, you'll also be able to require the policy be > > signed. > > To clarify, the policy being measured by this patch series is a > serialized representation of the in-memory policy data structures being > enforced by SELinux. Not the file that was loaded. Hence, this > measurement would detect tampering with the in-memory policy data > structures after the policy has been loaded. In the case of SELinux, > one can read this serialized representation via /sys/fs/selinux/policy. > The result is not byte-for-byte identical to the policy file that was > loaded but can be semantically compared via sediff and other tools to > determine whether it is equivalent. Thank you for the clarification. Could the policy hash be included with the other critical data? Does it really need to be measured independently? Mimi