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=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 95899C43381 for ; Wed, 6 Mar 2019 12:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F9EC20840 for ; Wed, 6 Mar 2019 12:30:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729896AbfCFMai (ORCPT ); Wed, 6 Mar 2019 07:30:38 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:45062 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729845AbfCFMai (ORCPT ); Wed, 6 Mar 2019 07:30:38 -0500 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x26CP8N4093749 for ; Wed, 6 Mar 2019 07:30:37 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2r2cejev3k-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 06 Mar 2019 07:30:36 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 6 Mar 2019 12:30:31 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x26CUU2K33751270 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 6 Mar 2019 12:30:31 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C85BE11C064; Wed, 6 Mar 2019 12:30:29 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 20DD911C050; Wed, 6 Mar 2019 12:30:29 +0000 (GMT) Received: from localhost.localdomain (unknown [9.80.106.126]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 6 Mar 2019 12:30:28 +0000 (GMT) Subject: Re: [PATCH V2 3/4] IMA: Optionally make use of filesystem-provided hashes From: Mimi Zohar To: Matthew Garrett Cc: linux-integrity , Dmitry Kasatkin , linux-fsdevel@vger.kernel.org, miklos@szeredi.hu Date: Wed, 06 Mar 2019 07:30:18 -0500 In-Reply-To: References: <20190226215034.68772-1-matthewgarrett@google.com> <20190226215034.68772-4-matthewgarrett@google.com> <1551369834.10911.195.camel@linux.ibm.com> <1551377110.10911.202.camel@linux.ibm.com> <1551391154.10911.210.camel@linux.ibm.com> <1551731553.10911.510.camel@linux.ibm.com> <1551791930.31706.41.camel@linux.ibm.com> <1551815469.31706.132.camel@linux.ibm.com> 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: 19030612-0008-0000-0000-000002C93BAE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19030612-0009-0000-0000-0000223545D9 Message-Id: <1551875418.31706.158.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-06_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903060086 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, 2019-03-05 at 12:27 -0800, Matthew Garrett wrote: > On Tue, Mar 5, 2019 at 11:51 AM Mimi Zohar wrote: > > On Tue, 2019-03-05 at 10:39 -0800, Matthew Garrett wrote: > > > We can trust in-kernel filesystems to return reliable information. > > > Network filesystems have the same issue as FUSE - we're trusting that > > > the remote endpoint won't give us different information on successive > > > reads. What's the threat that's blocked by requiring signed policy > > > here? > > > > Today, IMA calculates the file hash by reading the file. If > > "get_hash" is a generic filesystem ops, then any filesystem could > > implement it, properly or not. sysadmins shouldn't have to review > > kernel code to understand the source of the file hash, but should be > > able to assume that unless they explicitly authorize "get_hash" usage, > > IMA reads the file and calculates the file hash. > > But what's the threat? If an attacker is in a position to inject > additional IMA policy then in general they're already in a position to > violate other security assumptions. Admins who have a threat model > that includes an attacker being able to do this are already requiring > signed policy. What's the threat that requiring signed policy for this > specific option mitigates? That might be true, but this "feature" isn't a minor change.  It totally changes the IMA measurement list meaning, without any indication of the change in meaning. Mimi