RE: [Xense-devel] Run vTPM in its own VM?

[Stefan Berger <stefanb@xxxxxxxxxx>]

"Scarlata, Vincent R" <vincent.r.scarlata@xxxxxxxxx>
wrote on 09/14/2006 05:01:58 PM:

> The simple case is that all the DomUvTPM domains are the same, and
> therefore have the same measurement. (Note these should be single
> app domains where the only thing in them is a kernel, vtpm, and the
> supporting libraries). Then the measurement of all the code in this
> domain goes in a PCR in the real TPM.
>  
> I don't follow your question about the 2 vTPMs
in Dom0 though. Can 
> you elaborate?

You are right, it does not make sense to spawn 2 new
virtual TPM instances for your virtual TPM domains. You would measure the
kernel and initrd of the vTPM domain into the hardware TPM and not care
at the level of application runtime measurements taken  *inside* a
vTPM domain. 

Regarding the model below. Why do you still need the
vtpm_managerd in dom-0? Isn't access to persistent storage for the vTPM-hosting
domain sufficient so the vTPM can serialize and deserialize its state when
need? If you shut down the vTPM-hosting domain one could use the existing
shutdown mechanism ('shutdown' is launched) to notify the vTPM to serialize
its state to persistent storage.

   Stefan


>  
> -Vinnie
> 
> From: Stefan Berger [mailto:stefanb@xxxxxxxxxx] 
> Sent: Thursday, September 14, 2006 1:19 PM
> To: Scarlata, Vincent R
> Cc: Fischer, Anna; Xense-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xense-devel] Run vTPM in its own VM?

> 
> The question then is where to these vTPM-hosting domains stick their
> measurements into? I guess you will have to spawn 2 virtual TPM 
> instances in domain-0 to give those domains vTPM access. 
> 
> -- Stefan 
> 
> "Scarlata, Vincent R" <vincent.r.scarlata@xxxxxxxxx>
wrote on 
> 09/14/2006 03:59:27 PM:
> 
> > Current, I guess they are "trusted," but this is an
artifact of Xen 
> > not yet having a measurement infrastructure for measuring domains
> > that get launched. It is not the intention to have these domains
be 
> > implicitly trusted. 
> >   
> > -Vinnie 
> > 
> > From: Stefan Berger [mailto:stefanb@xxxxxxxxxx] 
> > Sent: Thursday, September 14, 2006 12:53 PM
> > To: Scarlata, Vincent R
> > Cc: Fischer, Anna; Xense-devel@xxxxxxxxxxxxxxxxxxx; xense-devel-
> > bounces@xxxxxxxxxxxxxxxxxxx
> > Subject: RE: [Xense-devel] Run vTPM in its own VM?
> 
> > 
> > Are DomU1vTPM and DomU2vTPM 'trusted' or are these domains also
> > implementing a transitive trust model with  integrity measurements
> > taken inside of them? 
> > 
> > -- Stefan 
> > 
> > xense-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 09/14/2006 02:30:40
PM:
> > 
> > > No, there is only 1 vtpm_manager per platform. As you noted
the vTPMs
> > > have a VTPM_MULTI_VM switch. This switch does 2 things.
1) determines if
> > > it reads vTPM commands from a backend or from a FIFO, and
2) if it sends
> > > vtpm control commands to the manager via a tpm frontend
or another FIFO.
> > > 
> > > So in multivm mode, it looks like the following (which will
either clear
> > > things up, or completely confuse them).
> > > 
> > >                
        |----- DomU1vTPM ---| |----- DomU1 ----|
> > >                
      /--> FE ~ vtpmd ~ BE <---> FE ~ vtpm drv
|
> > > |----- Dom 0 ------|  | |-------------------| |----------------|
> > > vtpm_managerd ~ BE <--+
> > >                
      | |----- DomU2vTPM ---| |----- DomU2 ----|
> > >                
      \--> FE ~ vtpmd ~ BE <---> FE ~ vtpm drv
|
> > >                
        |-------------------| |----------------|
> > > 
> > > 
> > >                
      ^              
       ^
> > >                
      |              
       |
> > >                save/load
cmds             tpm cmds
> > > 
> > > 
> > > The vtpm still has this code in it. The missing code is
in the manager.
> > > To support both models the manager had become very complex.
In the multi
> > > vm case, only control commands came in. In the single vm
case, the
> > > manager received tpm commands or control commands (open/close
vtpm),
> > > handle the control commands and forward tpm commands to
a vtpm, while
> > > accepting control commands (save/load nv) on a different
channel. This
> > > was all done through 1 command handler with a mess of #ifdefs.
> > > 
> > > I rewrote the handler routines and threading routines to
be more
> > > generalized. Now everything is mode agnostic to the number
of vms except
> > > manager/vtpmd.c. This file defines the necessary threads,
FIFO, and
> > > handlers instances. The current file is a couple hundred
lines and sets
> > > everything up for single vm. I plan on writing another vtpmd.c
which
> > > sets the manager up for multivm mode. I will then use some
sort of a
> > > selector to determine which file to compile based on your
mode or maybe
> > > build 2 apps. This is why I call it incomplete.
> > >                
                     
       
> > > -Vinnie
> > > 
> > > -----Original Message-----
> > > From: Fischer, Anna [mailto:anna.fischer@xxxxxx] 
> > > Sent: Thursday, September 14, 2006 10:27 AM
> > > To: Scarlata, Vincent R; Xense-devel@xxxxxxxxxxxxxxxxxxx
> > > Subject: RE: [Xense-devel] Run vTPM in its own VM?
> > > 
> > > Thanks for your reply.
> > > 
> > > But do I understand it correctly that in your design you
will have a
> > > vTPM manager running in each vTPM BE domain? And you have
the vTPM then
> > > talking again through FIFOs to the vTPM manager who talks
to the BE? 
> > > 
> > > However, the code seems to be designed so that the vTPMs
talk directly
> > > to the BE. Is that what you mean with that the code for
this
> > > configuration is broken? According to the currently implemented
design I
> > > don't see how such a direct communication can work as for
example
> > > capabilities like saving and loading NVRAM won't work without
having the
> > > vTPM manager in between, right?
> > > 
> > > Anna
> > > 
> > > -----Original Message-----
> > > From: Scarlata, Vincent R [mailto:vincent.r.scarlata@xxxxxxxxx]
> > > Sent: Donnerstag, 14. September 2006 17:59
> > > To: Fischer, Anna; Xense-devel@xxxxxxxxxxxxxxxxxxx
> > > Subject: RE: [Xense-devel] Run vTPM in its own VM?
> > > 
> > > Sorry Anna, the documentation is both slightly out of date,
and slightly
> > > ahead of its time. :-)
> > > 
> > > The vtpm manager was architected to allows each vtpm instance
to run in
> > > its own VM, but during the last restructuring of the code,
support for
> > > this configuration was broken. It's now incomplete. Due
to other
> > > commitments, I won't be able to get back to this immediately,
I hope to
> > > submit a patch to re-enable this config options within a
month-ish.
> > > 
> > > The way it looked and will look again is the following.
A standard
> > > config would be a Dom0, DomU1 guest, DomU1vTPM vtpm domain,
... DomUn,
> > > DomUnvTPM. DomU1 has a tpm FE, for which DomU1vTPM has the
BE. Similarly
> > > DomU2 has a tpm FE, for which DomU2vTPM has the BE. This
allows direct
> > > communication between the DomU and it's vTPM, as you mention
below. Then
> > > all the DomU*vTPM domains have tpm FEs, for which the domain
housing the
> > > vtpm manager is the BE. By default this is Dom0, but provided
that the
> > > tpm device can be assigned to a different domain, this can
be put in any
> > > domain. The vtpm_manager's domain has the tpm driver.
> > > 
> > > This is a little heavier weight than running everything
in dom0, but it
> > > removes the manager from being a bottle neck in tpm access,
since all
> > > DomUs can access their vTPMs simultaneously (though the
manager can
> > > still only handle 1 vtpm request at a time to save internal
states).
> > > Also isolation between vtpms is established.
> > > 
> > > Do you need this functionality, or are you just doing thought
> > > experiments?
> > > 
> > > Hopes this answers your questions,
> > > 
> > > -Vinnie Scarlata
> > >   Trusted Platform Lab
> > >   Corporate Technology Group
> > >   Intel Corporation
> > > 
> > > -----Original Message-----
> > > From: xense-devel-bounces@xxxxxxxxxxxxxxxxxxx
> > > [mailto:xense-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf
Of Fischer,
> > > Anna
> > > Sent: Thursday, September 14, 2006 2:01 AM
> > > To: Xense-devel@xxxxxxxxxxxxxxxxxxx
> > > Subject: [Xense-devel] Run vTPM in its own VM?
> > > 
> > > The README of the current Xen unstable version says that
setting
> > > VTPM_MULTI_VM allows running each vTPM in its own VM. However,
compiling
> > > with this option doesn't work on my machine and the code
doesn't seem to
> > > be complete for this option.
> > > 
> > > Did I miss to configure something or is the current implementation
in
> > > Xen not really ready for running a vTPM in a separate VM?
> > > 
> > > Can you explain to me how a communication will look like
for the planned
> > > implementation in Xen? Will all communication continue to
go through the
> > > vTPM manager and the vTPM manager talks to a kind of FE
that transmits
> > > TPM commands to a BE running in a separate domain? Or is
it possible to
> > > set up direct connections between a user domain TPM FE and
the vTPM
> > > running in an isolated VM?
> > > 
> > > Regards,
> > > Anna
> > > 
> > > _______________________________________________
> > > Xense-devel mailing list
> > > Xense-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xense-devel
> > > 
> > > _______________________________________________
> > > Xense-devel mailing list
> > > Xense-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xense-devel
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