Tboot bootloader (Intel TXT) not Supported on UEFI Secure Boot Systems

This document (000019785) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 15

Situation

When installing and configuring the tboot bootloader (from the tboot package) on a UEFI Secure Boot enabled system, booting the trusted boot menu entry from within the Grub2 bootloader fails with the following message :

"error: can't find command `multiboot`" and "error: can't find command `module`".

Resolution

The tboot bootloader is not an EFI compatible binary and therefore not digitally signed appropriately to be part of a Secure Boot trust chain.

The tboot bootloader would allow to run arbitrary other machine code that is unsigned and thus would break the Secure Boot concept.

To use the tboot bootloader despite of this, it is possible to disable the Secure Boot feature in the machine's UEFI configuration. In this case the grub2 bootloader will allow to load the untrusted tboot bootloader.

However, using this approach, the Secure Boot security feature will be lost.
SUSE does not recommend this approach for typical installations.

Cause

The tboot bootloader, which allows to harness the Intel TXT security feature on Intel processors, is not compatible with UEFI Secure Boot enabled systems.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.