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Re: [Xen-devel] [PATCH v3 00/14] Enable vTPM subsystem on TPM 2.0

On 01/12/2015 11:06 AM, Xu, Quan wrote:
Now there are no more comments for this series of patch.
Can this series of patch be merged in staging branch? or any other AR, let me 
If the series of patch are in staging branch, the Community and I can continue 
to develop and enhance it.

A few remaining comments:

Patch 6 adds an #if 0 block; is this test code that you meant to remove?

Patch 9 (see reply).

Are you planning to replace TPM2_Bind with TPM2_Seal in a later series?
If so, please make a note of this limitation in the documentation for TPM2,
since using PCRs to seal the data can be an important security feature that
users of the vtpmmgr rely on.

For the other patches in this series (1-5,7-8,10):
Acked-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

With patch #14 documenting the lack of TPM2 sealing, #11-13 are also Acked.

- Daniel


-----Original Message-----
From: Xu, Quan
Sent: Wednesday, December 31, 2014 1:50 PM
To: xen-devel@xxxxxxxxxxxxx
Cc: dgdegra@xxxxxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx;
samuel.thibault@xxxxxxxxxxxx; ian.campbell@xxxxxxxxxx;
ian.jackson@xxxxxxxxxxxxx; jbeulich@xxxxxxxx; keir@xxxxxxx; tim@xxxxxxx; Xu,
Subject: [PATCH v3 00/14] Enable vTPM subsystem on TPM 2.0

# Happy New Year..#

This series of patch enable the virtual Trusted Platform Module (vTPM)
subsystem for Xen on TPM 2.0.

Noted, functionality for a virtual guest operating system (a DomU) is still TPM
1.2. The main modifcation is on vtpmmgr-stubdom. The challenge is that TPM
2.0 is not backward compatible with TPM 1.2.

The architecture of vTPM subsystem on TPM 2.0 is described below:

|    Linux DomU    | ...
|       |  ^       |
|       v  |       |
|   xen-tpmfront   |
         |  ^
         v  |
| mini-os/tpmback  |
|       |  ^       |
|       v  |       |
|  vtpm-stubdom    | ...
|       |  ^       |
|       v  |       |
| mini-os/tpmfront |
         |  ^
         v  |
| mini-os/tpmback  |
|       |  ^       |
|       v  |       |
| vtpmmgr-stubdom  |
|       |  ^       |
|       v  |       |
| mini-os/tpm2_tis |
         |  ^
         v  |
| Hardware TPM 2.0 |
  * Linux DomU: The Linux based guest that wants to use a vTPM. There many
                more than one of these.

  * xen-tpmfront.ko: Linux kernel virtual TPM frontend driver. This driver
                     provides vTPM access to a para-virtualized Linux based

  * mini-os/tpmback: Mini-os TPM backend driver. The Linux frontend driver
                     connects to this backend driver to facilitate
                     communications between the Linux DomU and its
vTPM. This
                     driver is also used by vtpmmgr-stubdom to
communicate with

  * vtpm-stubdom: A mini-os stub domain that implements a vTPM. There is a
                  one to one mapping between running vtpm-stubdom
instances and
                  logical vtpms on the system. The vTPM Platform
                  Registers (PCRs) are all initialized to zero.

  * mini-os/tpmfront: Mini-os TPM frontend driver. The vTPM mini-os domain
                      vtpm-stubdom uses this driver to communicate with
                      vtpmmgr-stubdom. This driver could also be used
separately to
                      implement a mini-os domain that wishes to use a
vTPM of
                      its own.
  * vtpmmgr-stubdom: A mini-os domain that implements the vTPM manager.
                There is only one vTPM manager and it should be running
                the entire lifetime of the machine.  This domain regulates
                access to the physical TPM on the system and secures the
                persistent state of each vTPM.

  * mini-os/tpm2_tis: Mini-os TPM version 2.0 TPM Interface Specification (TIS)
                     driver. This driver used by vtpmmgr-stubdom to talk
                     to the hardware TPM 2.0. Communication is facilitated
by mapping
                     hardware memory pages into vtpmmgr-stubdom.

  * Hardware TPM 2.0: The physical TPM 2.0 that is soldered onto the

Key Hierarchy

     |  vTPM's secrets  | ...
             |  ^
             |  |(Bind / Unbind)
- - - - -  -v  |- - - - - - - - TPM 2.0
     |        SK        +
             |  ^
             v  |
     |       SRK        |
             |  ^
             v  |
     | TPM 2.0 Storage  |
     |   Primary Seed   |

You must have an x86 machine with a TPM on the motherboard.  The only
extra software requirement for compiling vTPM is cmake.  You must use libxl
to manage domains with vTPMs; 'xm' is deprecated and does not support

Compiling the Xen tree:

Compile and install the Xen tree as usual; be sure that the vTPM domains are
enabled when you run configure.

Compiling the LINUX dom0 kernel:

Because the TPM manager uses direct access to the physical TPM, it may
interfere with access to the TPM by dom0.  The simplest solution for this is to
dom0 from accessing the physical TPM by compiling the kernel without a driver
or blacklisting the module.

Compiling the LINUX domU kernel:

The domU kernel used by domains with vtpms must include the xen-tpmfront.ko
driver. It can be built directly into the kernel or as a module; however, some
features such as IMA require the TPM to be built in to the kernel.



Manager disk image setup:

The vTPM Manager requires a disk image to store its encrypted data. The image
does not require a filesystem and can live anywhere on the host disk. The image
is not large; the Xen 4.5 vtpmmgr is limited to using the first 2MB of the image
but can support more than 20,000 vTPMs.

  dd if=/dev/zero of=/home/vtpm2/vmgr bs=16M count=1

Manager config file:

The vTPM Manager domain (vtpmmgr-stubdom) must be started like any other
Xen virtual machine and requires a config file.  The manager requires a disk
image for storage and permission to access the hardware memory pages for
the TPM. The disk must be presented as "hda", and the TPM memory pages are
passed using the iomem configuration parameter. The TPM TIS uses 5 pages of
IO memory (one per
locality) that start at physical address 0xfed40000. By default, the TPM manager
uses locality 0 (so only the page at 0xfed40 is needed).

extra option to launch vtpmmgr-stubdom domain on TPM 2.0, and ignore it on
TPM 1.x. for example:


vTPM disk image setup:

The vTPM requires a disk image to store its persistent data (RSA keys, NVRAM,
etc). The image does not require a filesystem. The image does not need to be
large; 2 Mb should be sufficient.

     dd if=/dev/zero of=/home/vtpm2/vtpm0 bs=2M count=1

vTPM config file:

The vTPM domain requires a configuration file like any other domain. The vTPM
requires a disk image for storage and a TPM frontend driver to communicate
with the manager.  You are required to generate a uuid for this vtpm, which is
specified on the "vtpm=" line that describes its connection to the vTPM
for example:



If you wish to clear the vTPM data you can either recreate the disk image or
change the uuid.

Linux Guest config file:
The Linux guest config file needs to be modified to include the Linux tpmfront
driver. Add the following line:


Currently only Linux guests are supported (PV or HVM with PV drivers). My series
of patch for HVM virtual mahcine are still being reviewed and modifcated.

Using the vTPM in the guest:

If xen-tpmfront was compiled as a module, it must be loaded it in the guest.

# modprobe xen-tpmfront

After the Linux domain boots and the xen-tpmfront driver is loaded, you should
see the following on the vtpm console:

Info: VTPM attached to Frontend X/Y

You can quickly test the vTPM by using the sysfs interface:
# cat /sys/devices/vtpm-0/pubek
# cat /sys/devices/vtpm-0/pcrs
If you have trousers and tpm_tools installed on the guest, the tpm_version
command should return the following:

The version command should return the following:
   TPM 1.2 Version Info:
   Chip Version:
   Spec Level:          2
   Errata Revision:     1
   TPM Vendor ID:       ETHZ
   TPM Version:         01010000
   Manufacturer Info:   4554485a

You should also see the command being sent to the vtpm console as well as the
vtpm saving its state. You should see the vtpm key being encrypted and stored
on the vtpmmgr console.

You may wish to write a script to start your vtpm and guest together and to
destroy the vtpm when the guest shuts down.

The vTPM currently starts up with all PCRs set to their default values (all 
for the lower 16).  This means that any decisions about the trustworthiness of
the created domain must be made based on the environment that created the
vTPM and the domU; for example, a system that only constructs images using a
trusted configuration and guest kernel be able to provide guarantees about the
guests and any measurements done that kernel (such as the IMA TCB log).
Guests wishing to use a custom kernel in such a secure environment are often
started using the pv-grub bootloader as the kernel, which then can load the
untrusted kernel without needing to parse an untrusted filesystem and kernel in
dom0.  If the pv-grub stub domain succeeds in connecting to a vTPM, it will
extend the hash of the kernel that it boots into PCR #4, and will extend the
command line and initrd into PCR #5 before booting so that a domU booted in
this way can attest to its early boot state.


Berlios TPM Emulator:
Xen docs/misc/vtpm.txt
Xen docs/misc/vtpm-platforms.txt
Xen docs/misc/vtpmmgr.txt

--Changes in V3:
   1. Add 'olen' parameter in 'stubdom/vtpmmgr/disk_read.c', which is lost in

--Changes in V2:
   1. Record some infomation in docs/misc/vtpmmgr.txt.
   2. Add TPM 2.0 PCRs read.
   3. Bind/Unbind the measurements of the hypervisor and other
      TCB components.
   4. Change extra option from '--tpm2' to 'tpm2'

Quan Xu (14):
   vTPM/TPM2: Add TPM 2.0 data structures and commands definition
   vTPM/TPM2: TPM 2.0 data structures marshal
   vTPM/TPM2: Add global data in vtpm_globals{}
   vTPM/TPM2: Add TPM 2.0 Exposed APIs
   vTPM/TPM2: TPM 2.0 takes ownership and create SRK
   vTPM/TPM2: Create and load SK on TPM 2.0
   vTPM/TPM2: TPM2.0 TIS initialization and self test.
   vTPM/TPM2: Add main entrance vtpmmgr2_init()
   vTPM/TPM2: Support 'tpm2' extra command line.
   vTPM/TPM2: TPM 2.0 PCRs read
   vTPM/TPM2: Support TPM 2.0 bind and unbind data
   vTPM/TPM2: Bind group keys and sectors data on disk
   vTPM/TPM2: Unind group keys and sectors data on disk
   vTPM/TPM2: Record some infomation in docs/misc/vtpmmgr.txt about

  docs/misc/vtpmmgr.txt            | 150 +++++-
  extras/mini-os/include/tpm_tis.h |   1 +
  extras/mini-os/tpm_tis.c         | 156 +++++++
  stubdom/vtpmmgr/Makefile         |   2 +-
  stubdom/vtpmmgr/disk_read.c      |  17 +-
  stubdom/vtpmmgr/disk_tpm.c       |  42 +-
  stubdom/vtpmmgr/disk_tpm.h       |   4 +
  stubdom/vtpmmgr/disk_write.c     |  13 +-
  stubdom/vtpmmgr/init.c           | 315 +++++++++++++
  stubdom/vtpmmgr/tpm2.c           | 455 ++++++++++++++++++
  stubdom/vtpmmgr/tpm2.h           | 104 +++++
  stubdom/vtpmmgr/tpm2_marshal.h   | 673
  stubdom/vtpmmgr/tpm2_types.h     | 980
  stubdom/vtpmmgr/vtpmmgr.c        |  46 +-
  stubdom/vtpmmgr/vtpmmgr.h        |  29 ++
  15 files changed, 2973 insertions(+), 14 deletions(-)  create mode 100644
stubdom/vtpmmgr/tpm2.c  create mode 100644 stubdom/vtpmmgr/tpm2.h
create mode 100644 stubdom/vtpmmgr/tpm2_marshal.h  create mode
100644 stubdom/vtpmmgr/tpm2_types.h


Daniel De Graaf
National Security Agency

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