[RFC][PATCH 0a/3] TXT: Intel(R) Trusted Execution Technology support for Linux - Overview

[Cihula, Joseph]

Linux community,

The following patches are to add support for Intel(R) Trusted Execution
Technology (Intel(R) TXT) and the Trusted Boot open source project
(tboot).

We request your feedback and suggestions.



Intel(R) TXT Overview:
=====================

Intel's technology for safer computing, Intel(R) Trusted Execution
Technology
(Intel(R) TXT), defines platform-level enhancements that provide the
building
blocks for creating trusted platforms.

Intel TXT was formerly known by the code name LaGrande Technology (LT).

Intel TXT in Brief:
o  Provides dynamic root of trust for measurement (DRTM)
o  Data protection in case of improper shutdown
o  Measurement and verification of launched environment

Intel TXT is part of the vPro(TM) brand and is also available some
non-vPro
systems.  It is available on systems based on the Q35 or X38 Express
chipsets
(e.g. Dell Optiplex 755, HP dc7800, etc.).  However, TXT will be on all
vPro(TM) client platforms starting this year (Montevina and McCreary
-based),
with plans for server support in the near future.

For more information, see http://www.intel.com/technology/security/.
This
site also has a link to the Intel TXT MLE Developers Manual, which has
been updated for the new released platforms.

Intel TXT has been presented at various events over the past few years,
some
of which are:
      LinuxTAG 2008:
http://www.linuxtag.org/2008/en/conf/events/vp-donnerstag/details.html?t
alkid=110
      TRUST2008:
http://www.trust2008.eu/downloads/Keynote-Speakers/3_David-Grawrock_The-
Front-Door-of-Trusted-Computing.pdf
      IDF 2008, Shanghai:
http://inteldeveloperforum.com.edgesuite.net/shanghai_2008/aep/PROS003/i
ndex.html
      IDFs 2006, 2007 (I'm not sure if/where they are online)

Trusted Boot Project Overview:
=============================

Trusted Boot (tboot) is an open source, pre- kernel/VMM module that uses
Intel TXT to perform a measured and verified launch of an OS kernel/VMM.

It is hosted on SourceForge at http://sourceforge.net/projects/tboot.

Tboot currently supports launching Xen (open source VMM/hypervisor w/
TXT
support since v3.2), and now Linux kernels.  Linux support is provided
in the
latest (tboot-20081007) release.


Value Proposition for Linux or "Why should you care?"
=====================================================

While there are many products and technologies that attempt to measure
or
protect the integrity of a running kernel, they all assume the kernel is
"good" to begin with.  The Integrity Measurement Architecture (IMA) and
Linux
Integrity Module interface are examples of such solutions.

To get trust in the initial kernel without using Intel TXT, a static
root of
trust must be used.  This bases trust in BIOS starting at system reset
and
requires measurement of all code executed between system reset through
the
completion of the kernel boot as well as data objects used by that code.
In
the case of a Linux kernel, this means all of BIOS, any option ROMs, the
bootloader and the boot config.  In practice, this is a lot of
code/data, much
of which is subject to change from boot to boot (e.g. changing NICs may
change
option ROMs).  Without reference hashes, these measurement changes are
difficult to assess or confirm as benign.  This process also does not
provide DMA protection, memory configuration/alias checks and locks,
crash
protection, or policy support.

By using the hardware-based root of trust that Intel TXT provides, many
of
these issues can be mitigated.  Specifically: many pre-launch components
can
be removed from the trust chain, DMA protection is provided to all
launched
components, a large number of platform configuration checks are
performed and
values locked, protection is provided for any data in the event of an
improper
shutdown, and there is support for policy-based execution/verification.
This
provides a more stable measurement and a higher assurance of system
configuration and initial state than would be otherwise possible.  Since
the
tboot project is open source, source code for almost all parts of the
trust
chain is available (excepting SMM and Intel-provided firmware).

Patchset:
========

These patches were tested on the 2.6.27-rc6 kernel and apply cleanly to
2.6.27-rc9.

Patch 0a/3:  Overview and motivation (this email)
Patch 0b/3:  Details and how it works
Patch 1/3:   Support for AddressRangeUnusuable ACPI memory type (already
             accepted but not in 2.6.27-rc9)
Patch 2/3:   Disable VT-d (Intel IOMMU) Protected Memory Regions (PMRs)
             (submitted to maintainer)
Patch 3/3:   Intel TXT and tboot support


Joseph Cihula
Shane Wang
Gang Wei
Intel Corp.
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