From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40743) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDZKM-0002tE-FN for qemu-devel@nongnu.org; Thu, 16 Jun 2016 11:35:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bDZKJ-00064m-50 for qemu-devel@nongnu.org; Thu, 16 Jun 2016 11:35:30 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49234) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDZKI-00064V-TI for qemu-devel@nongnu.org; Thu, 16 Jun 2016 11:35:27 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5GFYcrf111670 for ; Thu, 16 Jun 2016 11:35:26 -0400 Received: from e19.ny.us.ibm.com (e19.ny.us.ibm.com [129.33.205.209]) by mx0a-001b2d01.pphosted.com with ESMTP id 23ktnhkqyr-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 16 Jun 2016 11:35:25 -0400 Received: from localhost by e19.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 16 Jun 2016 11:35:24 -0400 References: <569FADC7.7060301@linux.vnet.ibm.com> <20160120162220.GH13215@redhat.com> <20160121113632.GC2446@work-vm> <57FA3A002D66E049AA7792D931B894C7060F5494@MOKSCY3MSGUSRGB.ITServices.sbc.com> <945CA011AD5F084CBEA3E851C0AB28894B8C3A14@SHSMSX101.ccr.corp.intel.com> <575E92DB.3080904@linux.vnet.ibm.com> <20160615193019.GB7300@work-vm> <5761C092.5070702@linux.vnet.ibm.com> <20160616080520.GA2249@work-vm> <5762BFE5.9070906@linux.vnet.ibm.com> <20160616152221.GD2249@work-vm> From: Stefan Berger Date: Thu, 16 Jun 2016 11:35:21 -0400 MIME-Version: 1.0 In-Reply-To: <20160616152221.GD2249@work-vm> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Message-Id: <5762C739.7060806@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH v5 1/4] Provide support for the CUSE TPM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: Stefan Berger , "mst@redhat.com" , "qemu-devel@nongnu.org" , "hagen.lauer@huawei.com" , "Xu, Quan" , "silviu.vlasceanu@gmail.com" , "SERBAN, CRISTINA" , "SHIH, CHING C" On 06/16/2016 11:22 AM, Dr. David Alan Gilbert wrote: > * Stefan Berger (stefanb@linux.vnet.ibm.com) wrote: >> On 06/16/2016 04:05 AM, Dr. David Alan Gilbert wrote: >>> * Stefan Berger (stefanb@linux.vnet.ibm.com) wrote: >>>> On 06/15/2016 03:30 PM, Dr. David Alan Gilbert wrote: >>> >>> >>>>> So what was the multi-instance vTPM proxy driver patch set about? >>>> That's for containers. >>> Why have the two mechanisms? Can you explain how the multi-instance >>> proxy works; my brief reading when I saw your patch series seemed >>> to suggest it could be used instead of CUSE for the non-container case. >> The multi-instance vtpm proxy driver basically works through usage of an >> ioctl() on /dev/vtpmx that is used to spawn a new front- and backend pair. >> The front-end is a new /dev/tpm%d device that then can be moved into the >> container (mknod + device cgroup setup). The backend is an anonymous file >> descriptor that is to be passed to a TPM emulator for reading TPM requests >> coming in from that /dev/tpm%d and returning responses to. Since it is >> implemented as a kernel driver, we can hook it into the Linux Integrity >> Measurement Architecture (IMA) and have it be used by IMA in place of a >> hardware TPM driver. There's ongoing work in the area of namespacing support >> for IMA to have an independent IMA instance per container so that this can >> be used. >> >> A TPM does not only have a data channel (/dev/tpm%d) but also a control >> channel, which is primarily implemented in its hardware interface and is >> typically not fully accessible to user space. The vtpm proxy driver _only_ >> supports the data channel through which it basically relays TPM commands and >> responses from user space to the TPM emulator. The control channel is >> provided by the software emulator through an additional TCP or UnixIO socket >> or in case of CUSE through ioctls. The control channel allows to reset the >> TPM when the container/VM is being reset or set the locality of a command or >> retrieve the state of the vTPM (for suspend) and set the state of the vTPM >> (for resume) among several other things. The commands for the control >> channel are defined here: >> >> https://github.com/stefanberger/swtpm/blob/master/include/swtpm/tpm_ioctl.h >> >> For a container we would require that its management stack initializes and >> resets the vTPM when the container is rebooted. (These are typically >> operations that are done through pulses on the motherboard.) >> >> In case of QEMU we would need to have more access to the control channel, >> which includes initialization and reset of the vTPM, getting and setting its >> state for suspend/resume/migration, setting the locality of commands, etc., >> so that all low-level functionality is accessible to the emulator (QEMU). >> The proxy driver does not help with this but we should use the swtpm >> implementation that either has that CUSE interface with control channel >> (through ioctls) or provides UnixIO and TCP sockets for the control channel. > OK, that makes sense; does the control interface need to be handled by QEMU > or by libvirt or both? The control interface needs to be handled primarily by QEMU. In case of the libvirt implementation I am running an external program swtpm_ioctl that uses the control channel to gracefully shut down any existing running TPM emulator whose device name happens to have the same name as the device of the TPM emulator that is to be created. So it cleans up before starting a new TPM emulator just to make sure that that new TPM instance can be started. Detail... > Either way, I think you're saying that with your kernel interface + a UnixIO > socket you can avoid the CUSE stuff? So in case of QEMU you don't need that new kernel device driver -- it's primarily meant for containers. For QEMU one would start the TPM emulator and make sure that QEMU has access to the data and control channels, which are now offered as - CUSE interface with ioctl - TCP + TCP - UnixIO + TCP - TCP + UnioIO - UnixIO + UnixIO - file descriptors passed from invoker Stefan