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=-2.2 required=3.0 tests=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 40E83C43331 for ; Mon, 30 Mar 2020 02:10:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19D2C206E6 for ; Mon, 30 Mar 2020 02:10:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727801AbgC3CKc (ORCPT ); Sun, 29 Mar 2020 22:10:32 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:60844 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbgC3CKc (ORCPT ); Sun, 29 Mar 2020 22:10:32 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 02U24IWb005272 for ; Sun, 29 Mar 2020 22:10:31 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 301yfe60c6-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Sun, 29 Mar 2020 22:10:31 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 30 Mar 2020 03:10:17 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (9.149.109.194) by e06smtp05.uk.ibm.com (192.168.101.135) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 30 Mar 2020 03:10:14 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 02U2APcH60817544 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 30 Mar 2020 02:10:25 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 489D9A4055; Mon, 30 Mar 2020 02:10:25 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 544B1A4040; Mon, 30 Mar 2020 02:10:24 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.197.133]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 30 Mar 2020 02:10:24 +0000 (GMT) Subject: Re: Immutable metadata From: Mimi Zohar To: Roberto Sassu , "matthewgarrett@google.com" Cc: "linux-integrity@vger.kernel.org" , Silviu Vlasceanu Date: Sun, 29 Mar 2020 22:10:23 -0400 In-Reply-To: References: 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-GCONF: 00 x-cbid: 20033002-0020-0000-0000-000003BDF231 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20033002-0021-0000-0000-000022168B05 Message-Id: <1585534223.5188.408.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.645 definitions=2020-03-29_10:2020-03-27,2020-03-29 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 mlxscore=0 phishscore=0 clxscore=1015 bulkscore=0 malwarescore=0 spamscore=0 mlxlogscore=871 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003300013 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Hi Roberto, On Sat, 2020-03-28 at 11:18 +0000, Roberto Sassu wrote: > Hi Matthew, Mimi > > I have a question about portable signatures. Is there any particular reason > why a write to a file is not denied by IMA if metadata are immutable? As much as possible, IMA and EVM should be independent of each other.  EVM is responsible for the integrity of file metadata, so it needs to read other security xattrs, but IMA shouldn't be looking at the EVM xattr. Like any other security xattr, responsibility for maintaining the xattr is left up to the particular LSM.  In this case, EVM would need to prevent the file from being opened rw.  Should that be hard coded or based on an EVM policy? Mimi