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[RFC v2][PATCH 0a/1] intel_txt: Intel(R) Trusted Execution Technology support for Linux - Overview

From:  Joseph Cihula <>
Subject:  [RFC v2][PATCH 0a/1] intel_txt: Intel(R) Trusted Execution Technology support for Linux - Overview
Date:  Mon, 30 Mar 2009 22:14:05 -0700
Message-ID:  <>
Archive-link:  Article

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

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
currently available on desktop systems based on the Q35, X38, Q45, and Q43 Express chipsets (e.g.
Dell Optiplex 755, HP dc7800, etc.) and mobile systems based on the GM45, PM45, and GS45 Express

For more information, see  
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:
      IDF 2008, Shanghai:
      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  The mercurial source repo is
available at

Tboot currently supports launching Xen (open source VMM/hypervisor w/ TXT support since v3.2), and
now Linux kernels.

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

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).


These patches were tested on the 2.6.29-tip git tree and apply cleanly.

Patch 0a/1:  Overview and motivation (this email)
Patch 0b/1:  Details and how it works
Patch 1/1:   Intel TXT and tboot support

Joseph Cihula
Shane Wang
Intel Corp.

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