From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1165467AbdEYUdA (ORCPT ); Thu, 25 May 2017 16:33:00 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52512 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S936158AbdEYUc6 (ORCPT ); Thu, 25 May 2017 16:32:58 -0400 Subject: Re: [PATCH] tpm: vtpm_proxy: Do not run tpm2_shutdown To: Jason Gunthorpe References: <1495717956-14252-1-git-send-email-stefanb@linux.vnet.ibm.com> <20170525155059.GA5151@obsidianresearch.com> <20170525200931.GA12733@obsidianresearch.com> Cc: jarkko.sakkinen@linux.intel.com, tpmdd-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org From: Stefan Berger Date: Thu, 25 May 2017 16:32:50 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20170525200931.GA12733@obsidianresearch.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17052520-0020-0000-0000-00000C0515FB X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007116; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00865570; UDB=6.00429816; IPR=6.00645367; BA=6.00005375; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015583; XFM=3.00000015; UTC=2017-05-25 20:32:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052520-0021-0000-0000-00005C7D18AE Message-Id: <9ff88c24-ca7a-1867-7284-17689fdac655@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-25_16:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705250374 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/25/2017 04:09 PM, Jason Gunthorpe wrote: > On Thu, May 25, 2017 at 04:04:24PM -0400, Stefan Berger wrote: >> On 05/25/2017 11:50 AM, Jason Gunthorpe wrote: >>> On Thu, May 25, 2017 at 09:12:36AM -0400, Stefan Berger wrote: >>>> The tpm2_shutdown does not work with the VTPM proxy driver since the >>>> function only gets called when the backend file descriptor is already >>>> closed and at this point no data can be sent anymore. A proper shutdown >>>> would have to be initated by a user space application, such as a container >>>> management stack, that sends the command via the character device before >>>> terminating the TPM emulator. >>>> >>>> To avoid the tpm2_shutdown we introduce a TPM_CHIP_FLAG_NO_SHUTDOWN flag >>>> that only the VTPM proxy driver sets. This also avoids misleading kernel >>>> log messages. >>> This seems strange to me.. >>> >>> Why isn't ops null if the fd has gone away? >>> >>> What is the call flow that hits this? >> In this function here. >> >> static void tpm_del_char_device(struct tpm_chip *chip) >> { >> cdev_device_del(&chip->cdev, &chip->dev); >> >> /* Make the chip unavailable. */ >> mutex_lock(&idr_lock); >> idr_replace(&dev_nums_idr, NULL, chip->dev_num); >> mutex_unlock(&idr_lock); >> >> /* Make the driver uncallable. */ >> down_write(&chip->ops_sem); >> if (chip->flags & TPM_CHIP_FLAG_TPM2) >> tpm2_shutdown(chip, TPM2_SU_CLEAR); >> chip->ops = NULL; >> up_write(&chip->ops_sem); >> } >> >> The request cannot be deliver because the anonymous fd has been closed >> already. > The driver must always be able to process requests until > tpm_del_char_device completes, so this is triggering an existing bug > in vtpm. This change in core behvior is not going to fix the bug. > > eg a request from sysfs/etc could come in between vtpm fd closure and > tpm_del_char_device, and it still must be handled properly. > > I guess you need to have transmit command fail fast once the fd is > closed. It doesn't hang. Everything is torn down immediately. What is primarily annoying are these two log messages: tpm tpm0: tpm_transmit: tpm_send: error -32 tpm tpm0: transmit returned -32 while stopping the TPM Stefan