Messages in this thread | | | Date | Mon, 23 Sep 2013 14:42:32 -0600 | From | Jason Gunthorpe <> | Subject | Re: [tpmdd-devel] [PATCH 09/13] tpm: Pull everything related to sysfs into tpm-sysfs.c |
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On Mon, Sep 23, 2013 at 04:20:51PM -0400, Daniel De Graaf wrote:
> That's fine; it wasn't really advertised in the description, and was > mostly added in order to demonstrate the locality security label binding > in Xen's vtpm-stubdom.
Ok, lets take it out for now then? I'll send a patch.
> >It looks like this driver was introduced in the 3.12 merge window, we > >could drop the attribute, and try to merge a core supported locality > >API in 3.13? What do you think? > > > >But, if you say it is needed, it is easy enough to adjust this patch > >series.
> If it's replaced with an alternative, I don't think the sysfs attribute > will need to remain. I am not aware of any clients that currently use > this attribute. The sysfs attribute could remain as the common interface > for changing locality, unless you think an ioctl on /dev/tpm0 or > something else would be preferable (the attribute was just the simplest > way to implement locality switching at the time).
Off the very top of my head:
I suspect that a good API would be a sysfs attribute 'default_locality' and an IOCTL to change localities. The default_locality would only take effect when the /dev/tpmX is opened, so fiddling with sysfs doesn't break active users.
The struct ops I've added would have a function to change localities, some of the generic TPM functions should be revised to have a locality argument.
Some thought is needed to determine what locality in-kernel users should be using. I suspect userspace and kernel space should not be forced to the same locality.
Should user space be restricted to a subset of localities?
What use models do you see with the security label binding mechanism you have on the hypervisor side?
Jason
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