Messages in this thread | | | Date | Thu, 4 May 2017 11:20:42 -0600 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v3 1/3] tpm: vtpm_proxy: Implement new ioctl to get supported flags |
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On Thu, May 04, 2017 at 01:13:18PM -0400, Stefan Berger wrote: > On 05/04/2017 11:34 AM, Jason Gunthorpe wrote: > >On Thu, May 04, 2017 at 10:56:25AM -0400, Stefan Berger wrote: > >>Implement VTPM_PROXY_IOC_GET_SUPT_FLAGS ioctl to get the bitmask > >>of flags that the vtpm_proxy driver supports in the > >>VTPM_PROXY_IOC_NEW_DEV ioctl. This helps user space in deciding > >>which flags to set in that ioctl. > >you might be better off just having a VTPM_PROXY_IO_ENABLE_FEATURE > >.feature = LOCALITY > > Do you have an example driver that shows how to do this ? Can user space > query that feature?
Try and enable the feature, if it fails then there is no feature in the kernel.
This is the usual way to add new syscalls..
> >If that fails then the feature is not supported, no real need for the > >query in that case. > > > >Not sure about Jarkko's point on request/release locality.. Is there a > >scenario where the emulator should fail the request locality? > > We could filter localities 5 and higher on the level of the driver (patch > 2/3) since basically there are only 5 localities (0-4) in any TPM interface > today. The typical hardware locality 4 would be filtered by the emulator per > policy passed via command line, but I would allow it on the level of this > driver. An error message would be returned for any command executed in that > locality, unless the 'policy' allows it. Localities 0-3 should just be > selectable. The TPM TIS (in the hardware) implements some complicated scheme > when it comes to allowing the selection of a locality and I would say we > need none of that but just tell the vTPM proxy driver the locality (patch > 2/3) in which the next command will be executed.
Well, if TIS hardware has some scheme I feel like the emulator uAPI should have enough fidelity to ecompass existing hardware, even if your current emulator does not need it.
So allowing request_locality to fail from userspace seems reasonable.
Jason
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