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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8572C433F5 for ; Fri, 10 Dec 2021 16:40:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243801AbhLJQoO (ORCPT ); Fri, 10 Dec 2021 11:44:14 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:25238 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S243720AbhLJQoN (ORCPT ); Fri, 10 Dec 2021 11:44:13 -0500 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1BAF7U9i017555; Fri, 10 Dec 2021 16:40:23 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=TY+r8grz6q+7hi60lwKyE6YHE6wUKSRdDRWS7DffpEo=; b=mMXvQV0s9kc5ycCddQiHVMPnpUk/T7alI1SeQqjdes35S1tpqTFqFcG+FVxOz/4JXByf 0dM555Y5XcBb5Hbww9zsi9gKPvpEMQmviFnlIb/jNNsPJG/MZh77xrRAPgydN5NKF6EM Z2uaCtGrn0OWsUtIhWNCentIiJmh/m3vPY8n+6/8lk3vdzouFW5wHatT8w4l/mRroPBo kMKeyhUgmuYis6WNAFStzvohDEtUW/AzDPvlB4krb4n2VvySSTZZRLdXSDp9WfL7vepA 2WIv4EVvhu6VXqRyiLdbI022mrNwWt8WfeMYTxq7LInARWE++V9E9rjWsVaDYUPjMxi5 TA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 3cv6ww55s5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Dec 2021 16:40:22 +0000 Received: from m0098413.ppops.net (m0098413.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 1BAGOao2000894; Fri, 10 Dec 2021 16:40:22 GMT Received: from ppma01dal.us.ibm.com (83.d6.3fa9.ip4.static.sl-reverse.com [169.63.214.131]) by mx0b-001b2d01.pphosted.com with ESMTP id 3cv6ww55rx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Dec 2021 16:40:22 +0000 Received: from pps.filterd (ppma01dal.us.ibm.com [127.0.0.1]) by ppma01dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1BAGW4K9014879; Fri, 10 Dec 2021 16:40:21 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma01dal.us.ibm.com with ESMTP id 3cqyyeg2ch-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Dec 2021 16:40:20 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1BAGeJGZ55116238 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 10 Dec 2021 16:40:19 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E5DCD124053; Fri, 10 Dec 2021 16:40:18 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AF19A124074; Fri, 10 Dec 2021 16:40:18 +0000 (GMT) Received: from [9.47.158.152] (unknown [9.47.158.152]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 10 Dec 2021 16:40:18 +0000 (GMT) Message-ID: <4f05d611-6f92-6a12-803b-0e38a855a8b4@linux.ibm.com> Date: Fri, 10 Dec 2021 11:40:18 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v5 15/16] ima: Move dentries into ima_namespace Content-Language: en-US To: Mimi Zohar , jejb@linux.ibm.com, Christian Brauner Cc: linux-integrity@vger.kernel.org, serge@hallyn.com, containers@lists.linux.dev, dmitry.kasatkin@gmail.com, ebiederm@xmission.com, krzysztof.struczynski@huawei.com, roberto.sassu@huawei.com, mpeters@redhat.com, lhinds@redhat.com, lsturman@redhat.com, puiterwi@redhat.com, jamjoom@us.ibm.com, linux-kernel@vger.kernel.org, paul@paul-moore.com, rgb@redhat.com, linux-security-module@vger.kernel.org, jmorris@namei.org References: <20211208221818.1519628-1-stefanb@linux.ibm.com> <20211208221818.1519628-16-stefanb@linux.ibm.com> <20211209143428.ip6bwry5hqtee5vy@wittgenstein> <20211209143749.wk4agkynfqdzftbl@wittgenstein> <20211210114934.tacjnwryihrsx6ln@wittgenstein> <2587716d7d021c35e3b6ef22b6e30f44c2b3f98e.camel@linux.ibm.com> <6de8d349-74f8-7be4-3854-5c4ac72860ad@linux.ibm.com> <66b377f6-40b4-77da-c02b-2650fa72d0b4@linux.ibm.com> <9806a2ba-8b45-3bb8-22c5-797ab2affaac@linux.ibm.com> <70e68bb6fd8e70b32fa2404768a6240791546496.camel@linux.ibm.com> From: Stefan Berger In-Reply-To: <70e68bb6fd8e70b32fa2404768a6240791546496.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: fHfNlcNpVXk77ilf0duXpAjct9Q1Eyjy X-Proofpoint-ORIG-GUID: uhG-pH8hOEs4rBDs4FYowQ1bEk5jpy_N X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-10_05,2021-12-10_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 spamscore=0 mlxlogscore=999 clxscore=1015 priorityscore=1501 malwarescore=0 adultscore=0 suspectscore=0 mlxscore=0 impostorscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112100092 Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On 12/10/21 10:48, Mimi Zohar wrote: > On Fri, 2021-12-10 at 10:32 -0500, Stefan Berger wrote: >> On 12/10/21 10:26, Mimi Zohar wrote: >>> On Fri, 2021-12-10 at 09:26 -0500, James Bottomley wrote: >>>> On Fri, 2021-12-10 at 09:17 -0500, Stefan Berger wrote: >>>>> On 12/10/21 08:02, Mimi Zohar wrote: >>>>>> On Fri, 2021-12-10 at 07:40 -0500, Stefan Berger wrote: >>>>>>> On 12/10/21 07:09, Mimi Zohar wrote: >>>>>>>> On Fri, 2021-12-10 at 12:49 +0100, Christian Brauner wrote: >>>>>>>>>> There's still the problem that if you write the policy, >>>>>>>>>> making the file disappear then unmount and remount >>>>>>>>>> securityfs it will come back. My guess for fixing this is >>>>>>>>>> that we only stash the policy file reference, >>>>>>>>>> create it if NULL but then set the pointer to PTR_ERR(- >>>>>>>>>> EINVAL) or something and refuse to create it for that >>>>>>>>>> value. >>>>>>>>> Some sort of indicator that gets stashed in struct ima_ns >>>>>>>>> that the file does not get recreated on consecutive mounts. >>>>>>>>> That shouldn't be hard to fix. >>>>>>>> The policy file disappearing is for backwards compatibility, >>>>>>>> prior to being able to extend the custom policy. For embedded >>>>>>>> usecases, allowing the policy to be written exactly once might >>>>>>>> makes sense. Do we really want/need to continue to support >>>>>>>> removing the policy in namespaces? >>>>>>> I don't have an answer but should the behavior for the same >>>>>>> #define in this case be different for host and namespaces? Or >>>>>>> should we just 'select IMA_WRITE_POLICY and IMA_READ_POLICY' when >>>>>>> IMA_NS is selected? >>>>>> The latter option sounds good. Being able to analyze the namespace >>>>>> policy is really important. >>>>> Ok, I will adjust the Kconfig for this then. This then warrants the >>>>> question whether to move the dentry into the ima_namespace. The >>>>> current code looks like this. >>>>> >>>>> #if !defined(CONFIG_IMA_WRITE_POLICY) && >>>>> !defined(CONFIG_IMA_READ_POLICY) >>>>> securityfs_remove(ns->policy_dentry); >>>>> ns->policy_dentry = NULL; >>>>> ns->policy_dentry_removed = true; >>>>> #elif defined(CONFIG_IMA_WRITE_POLICY) >>>>> >>>>> With IMA_NS selecting IMA_WRITE_POLICY and IMA_READ_POLICY the above >>>>> wouldn't be necessary anymore but I find it 'cleaner' to still have >>>>> the dentry isolated rather than it being a global static as it was >>>>> before... >>>> This is really, really why you don't want the semantics inside the >>>> namespace to differ from those outside, because it creates confusion >>>> for the people reading the code, especially with magically forced >>>> config options like this. I'd strongly suggest you either keep the >>>> semantic in the namespace or eliminate it entirely. >>>> >>>> If you really, really have to make the namespace behave differently, >>>> then use global variables and put a big comment on that code saying it >>>> can never be reached once CONFIG_IMA_NS is enabled. >>> The problem seems to be with removing the securityfs policy file. >>> Instead of removing it, just make it inacessible for the "if >>> !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)" >>> case. >> So we would then leave it up to the one building the kernel to select >> the proper compile time options (suggested ones being IMA_WRITE_POLICY >> and IMA_READ_POLICY being enabled?) and behavior of host and IMA >> namespace is then the same per those options? Removing the file didn't >> seem the problem to me but more like whether the host should ever behave >> differently from the namespace. > You proposed "select IMA_WRITE_POLICY and IMA_READ_POLICY'" when IMA_NS > is selected. At least IMA_READ_POLICY should be enabled for > namespaces. > > In addition, if removing the securityfs file after a custom policy is > loaded complicates namespacing, then don't remove it. If we just leave the selection of the compile time options to the user (suggested ones being IMA_WRITE_POLICY and IMA_READ_POLICY being enabled) we don't need to make any changes. Choices are for IMA_NS: 1) Leave compile-time options to the user and suggest IMA_WRITE_POLICY and IMA_READ_POLICY 2) Auto-select IMA_WRITE_POLICY and IMA_READ_POLICY for IMA_NS and still remove file for non-IMA_NS case and have the dentry in the ima_namespace 3) Auto-select IMA_WRITE_POLICY and IMA_READ_POLICY for IMA_NS and still remove file for non-IMA_NS case and use global dentry 4) Changing mode bits on the file/inode to avoid having the dentry for v6 I just leave things as they are and we can then see what we need. > > thanks, > > Mimi >