Messages in this thread | | | Subject | Re: [PATCH 1/4] integrity: TPM internel kernel interface | From | Kenneth Goldman <> | Date | Wed, 13 Aug 2008 09:58:22 -0400 |
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Greg KH <greg@kroah.com> wrote on 08/12/2008 07:16:02 PM:
> On Tue, Aug 12, 2008 at 04:57:31PM -0400, Kenneth Goldman wrote: > > Christoph Hellwig <hch@infradead.org> wrote on 08/12/2008 03:30:31 PM: > > > > > And what happens when the chip simply goes away due to a hotplug action? > > > Or not even the actual chip goes away but just the chip driver and you > > > now dereference freed memory? > > > > Being a TCG/TPM person, I can only address the first question. The > > intent is that the TPM is soldered to the planar/motherboard (the TCG > > uses the phrase "bound to the platform"). I can't imagine > > any manufacturer designing a pluggable TPM. It would subvert PCR > > measurements and thus attestation, data sealing, etc. > > Load up the fake-php hotplug pci driver and "soft" disconnect it from > the system :) > > That was easy... > > Note, just because you think your device is always going to be soldered > to the motherboard, doesn't mean it can't be disconnected at any point > in time with the kernel running. > > Or the module could just be unloaded, that's also a very common thing to > have happen, right?
As I said, I'm a TCG/TPM person, so I can't address "the module could just be unloaded" or "hotplug pci driver". I'll leave that issue to the Linux driver experts.
I was using the common meaning of hotplug, removing and replacing a hardware component while power is on. By that common definition, the TPM would not be a hotpluggable component.
(As an aside, the TPM is commonly connected to the LPC bus on the planar, not the PCI bus.)
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