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=-0.8 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 1B5CDC43142 for ; Fri, 22 Jun 2018 11:40:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6D0224156 for ; Fri, 22 Jun 2018 11:40:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C6D0224156 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751370AbeFVLkq (ORCPT ); Fri, 22 Jun 2018 07:40:46 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33178 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291AbeFVLko (ORCPT ); Fri, 22 Jun 2018 07:40:44 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w5MBdxsx121294 for ; Fri, 22 Jun 2018 07:40:44 -0400 Received: from e15.ny.us.ibm.com (e15.ny.us.ibm.com [129.33.205.205]) by mx0a-001b2d01.pphosted.com with ESMTP id 2jrxynu2wj-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 22 Jun 2018 07:40:44 -0400 Received: from localhost by e15.ny.us.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) Fri, 22 Jun 2018 07:40:38 -0400 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5MBeblW2294092 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 22 Jun 2018 11:40:37 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C6435112065; Fri, 22 Jun 2018 07:40:33 -0400 (EDT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B07D1112064; Fri, 22 Jun 2018 07:40:33 -0400 (EDT) Received: from sbct-3.pok.ibm.com (unknown [9.47.158.153]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 22 Jun 2018 07:40:33 -0400 (EDT) Subject: Re: [PATCH v2 3/4] ima: Use tpm_chip_find() and access TPM functions using it To: Jason Gunthorpe Cc: Mimi Zohar , linux-integrity@vger.kernel.org, jarkko.sakkinen@linux.intel.com, linux-kernel@vger.kernel.org References: <20180620204236.1572523-1-stefanb@linux.vnet.ibm.com> <20180620204236.1572523-4-stefanb@linux.vnet.ibm.com> <1529614425.23843.20.camel@linux.vnet.ibm.com> <20180622032536.GB19151@ziepe.ca> From: Stefan Berger Date: Fri, 22 Jun 2018 07:40:37 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180622032536.GB19151@ziepe.ca> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-MW X-TM-AS-GCONF: 00 x-cbid: 18062211-0068-0000-0000-0000030CC99C X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009238; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000265; SDB=6.01050649; UDB=6.00538454; IPR=6.00829619; MB=3.00021804; MTD=3.00000008; XFM=3.00000015; UTC=2018-06-22 11:40:39 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18062211-0069-0000-0000-000044C588B8 Message-Id: <495fdcf7-b5b9-0341-796b-66fdf537811b@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-22_03:,, 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=8.0.1-1806210000 definitions=main-1806220133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/21/2018 11:25 PM, Jason Gunthorpe wrote: > On Thu, Jun 21, 2018 at 04:59:55PM -0400, Stefan Berger wrote: >> On 06/21/2018 04:53 PM, Mimi Zohar wrote: >>> On Wed, 2018-06-20 at 16:42 -0400, Stefan Berger wrote: >>>> Rather than accessing the TPM functions using a NULL pointer, which >>>> causes a lookup for a suitable chip every time, get a hold of a tpm_chip >>>> and access the TPM functions using this chip. We call the tpm_chip >>>> ima_tpm_chip and protect it, once initialization is done, using a >>>> rw_semaphore called ima_tpm_chip_lock. >>>> >>>> Use ima_shutdown to release the tpm_chip. >>>> >>>> Signed-off-by: Stefan Berger >>>> security/integrity/ima/ima.h | 3 +++ >>>> security/integrity/ima/ima_crypto.c | 12 ++++++++++-- >>>> security/integrity/ima/ima_init.c | 19 ++++++++++++------- >>>> security/integrity/ima/ima_queue.c | 7 +++++-- >>>> 4 files changed, 30 insertions(+), 11 deletions(-) >>>> >>>> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h >>>> index 354bb5716ce3..53a88d578ca5 100644 >>>> +++ b/security/integrity/ima/ima.h >>>> @@ -24,6 +24,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> >>>> #include "../integrity.h" >>>> @@ -56,6 +57,8 @@ extern int ima_policy_flag; >>>> extern int ima_used_chip; >>>> extern int ima_hash_algo; >>>> extern int ima_appraise; >>>> +extern struct rw_semaphore ima_tpm_chip_lock; >>>> +extern struct tpm_chip *ima_tpm_chip; >>> ima_add_templatE_entry() synchronizes appending a measurement to the >>> measurement list and extending the TPM by taking a lock.  Do we really >>> need to introduce another lock? >> This lock protects the ima_tpm_chip from going from != NULL to NULL in the >> ima_shutdown function. Basically, a global pointer accessed by concurrent >> threads should be protected if its value can change. However, in this case >> ima_shutdown would be called so late that there shouldn't be concurrency >> anymore. Though, I found it better to protect it. Maybe someone else has an >> opinion? > Why have a shutdown block? There is no harm in holding a kref if the > machine is shutting down. Looking around at other drivers' usage of the reboot notifier, I find other drivers as well that use spinlocks or mutexes during the shutdown. Besides that, we do have the shutdown block already when device_shutdown calls tpm_class_shutdown() and we get the ops_sem.     Stefan > > Jason >