From mboxrd@z Thu Jan 1 00:00:00 1970 From: jarkko.sakkinen@linux.intel.com (Jarkko Sakkinen) Date: Thu, 25 May 2017 15:33:48 -0700 Subject: [PATCH] tpm: vtpm_proxy: Do not run tpm2_shutdown In-Reply-To: <9ff88c24-ca7a-1867-7284-17689fdac655@linux.vnet.ibm.com> References: <1495717956-14252-1-git-send-email-stefanb@linux.vnet.ibm.com> <20170525155059.GA5151@obsidianresearch.com> <20170525200931.GA12733@obsidianresearch.com> <9ff88c24-ca7a-1867-7284-17689fdac655@linux.vnet.ibm.com> Message-ID: <20170525223348.uh66n37dnvz3eptl@intel.com> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Thu, May 25, 2017 at 04:32:50PM -0400, Stefan Berger wrote: > 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 It's been a while since I've looked into vtpm code. Why was fd closed before the above? I can go this through myself once I'm back in Finland next week. Just have forgotten this detail and do not have time to study this right now. /Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html