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Linux* TPM* Implementation

Ubuntu* OS version 20.04 on x86 was used as a development and execution OS. Follow these steps to compile and execute Secure Device Onboard (SDO).

The SDO build and execution depend on OpenSSL* toolkit version 1.1.1g. Users must install or upgrade the toolkit before compilation if the toolkit is not available by default in the environment.

1. Packages Requirements when Setting up TPM2.0 (on Ubuntu* OS version 20.04):

OpenSSL* toolkit version 1.1.1g. Follow the steps given in Section 10 to update the openssl version to 1.1.1g.

2. TPM* Library Installation (for Ubuntu OS version 20.04):

SDO TPM based client-sdk uses TPM-TSS 2.3.1, TPM2-ABRMD 2.2.0 and TPM2-TOOLS 4.0.1 libraries for key and cryptography related operations. The TPM-TSS library is required for compiling the code while all 3 libraries are required for running the code. Create an empty directory, download and execute SDO TPM TPM-Library-Installation-Script which can be used for both installation and uninstallation of TPM libraries. Alternatively, perform steps listed in section 2.1 to setup TPM library without using the TPM TPM-Library-Installation-Script.

To compile and execute TPM enabled SDO Client-SDK use one of the appropriate commands:

  • Script usage command
$ ./install_tpm_libs.sh -h
  • TPM-TSS library setup to enable TPM enabled SDO Client-SDK code compilation
# Command to install tpm-tss library
$ ./install_tpm_libs.sh -t

# Command to uninstall tpm-tss library
$ ./install_tpm_libs.sh -d
  • TPM setup to enable TPM enabled SDO Client-SDK code compilation and execution
# Command to install TPM libraries
$ ./install_tpm_libs.sh -i

# Command to uninstall TPM libraries
$ ./install_tpm_libs.sh -u

Note: Installation of these components may require elevated permissions. Please use 'sudo' to execute the script.

2.1 Building and Installing Libraries for Trusted Platform Module (TPM)

Following steps should be performed if SDO TPM TPM-Library-Installation-Script script is not used to setup SDO TPM libraries. Install only tpm2-tss library to enable TPM enabled SDO Client-SDK code compilation. To enable compilation and execution of TPM enabled SDO Client-SDK code, install all libraries namely: tpm2-tss, tpm2-abrmd, tpm2-tools, and tpm2-tss-engine.

2.1.1 tpm2-tss-2.3.1

This is the main library that creates commands per Trusted Computing Group (TCG) specification to use the TPM. It uses release version 2.3.1 of the library.

Source Code

The library can be downloaded from tpm2-tss-2.3.1-download

Build and Install Process

The build and installation process can be found at tpm2-tss-2.3.1-install

2.1.2 tpm2-abrmd-2.2.0

This is an optional but recommended library (daemon) to use TPM in the device. This daemon will act as a resource manager for the TPM, for all I/O calls that happen with the device. It uses release version 2.2.0 of the library.

Source Code

The library can be downloaded from tpm2-abrmd-2.2.0-download

Alternatively, the in-kernel RM /dev/tpmrm0 can be used. Please see Section on Compiling SDO.

Build and Install Process

The build and installation process found at tpm2-abrmd-2.2.0-install

2.1.3 tpm2-tools-4.0.1

This library provides the necessary tools to interact and perform operations using the TPM, to the users. It uses release version 4.0.1 of the library.

Source Code

The library can be downloaded from tpm2-tools-4.0.1-download

Build and Install Process

The build and installation process can be found at tpm2-tools-4.0.1-install

2.1.4 tpm2-tss-engine-1.1.0

This library provides the OpenSSL engine, which performs the OpenSSL cryptography operation using the keys inside the TPM. It uses release version 1.1.0 of the library.

Source Code

The library can be downloaded from tpm2-tss-engine-download

Build and Install Process

The build and installation process can be found at tpm2-tss-engine-install

3. Compiling Intel safestringlib

SDO client-sdk uses safestringlib for string and memory operations to prevent serious security vulnerabilities (For example, buffer overflows). Download safestringlib from intel-safestringlib, checkout to the tag v1.0.0 and follow these instructions to build: From the root of the safestringlib, do the following:

$ mkdir obj
$ make

After this step, libsafestring.a library will be created.

4. Environment Variables

Add these environment variables to ~/.bashrc or similar (replace with actual paths). Provide safestringlib path:

$ export SAFESTRING_ROOT=path/to/safestringlib

5. Compiling Service Info Modules (optional)

Provide the service-info device module path to use the SDO service-info functionality:

$ export SERVICE_INFO_DEVICE_MODULE_ROOT=path/to/service_info_module_dir

Service-info device module *.a must be present in the SERVICE_INFO_DEVICE_MODULE_ROOT, that is, required service-info device modules must be built prior to this step, otherwise the SDO client-sdk build will fail.

6. Compiling SDO

The SDO client-sdk build system is based on GNU make. assumes that all the requirements are set up according to SDO Compilation Setup . The application is built using the make [options] in the root of the repository for all supported platforms. The debug and release build modes are supported in building the SDO client-sdk.

Refer the TPM Library Setup steps given in Section 2 to compile TPM enabled SDO Client-SDK.

For an advanced build configuration, refer to Advanced Build Configuration .

Example command to build SDO TPM client-sdk with the Resource Manager as TPM2-ABRMD (tabrmd)

make pristine
cmake -DPK_ENC=ecdsa -DDA=tpm20_ecdsa256 .
make -j$(nproc)

To use the in-kernel Resource Manager '/dev/tpmrm0', use the following command

make pristine
cmake -DPK_ENC=ecdsa -DDA=tpm20_ecdsa256 -DTPM2_TCTI_TYPE=tpmrm0 .
make -j$(nproc)

Several other options to choose when building the device are, but not limited to, the following: device-attestation (DA) methods, Advanced Encryption Standard (AES) encryption modes (AES_MODE), key-exchange methods (KEX), Public-key encoding (PK_ENC) type, and SSL support (TLS). Refer to the section SDO Build configurations

7. Running the Application

The SDO Linux TPM device is compatible with SDO Supply Chain Toolkit (SCT) - Manufacturer and Reseller, Rendezvous, and IoT-Platform-SDK servers.

To test the SDO Linux device against the SDO Supply Chain Toolkit (SCT) - Manufacturer and Reseller, Rendezvous and IoT-Platform-SDK server binaries from the <release-package-dir>/SupplyChainTools/, <release-package-dir>/RendezvousServiceOnPrem/ and <release-package-dir>/SDOIotPlatformSDK/ directory respectively.

Refer the TPM Library Setup steps given in Section 2 to compile and execute TPM enabled SDO Client-SDK

After a successful compilation, the SDO Linux device executable can be found at <path-to-sdo-client-sdk>/build/linux/${BUILD}/linux-client.

Note: ${BUILD} can be either debug or release based on the compilation step.

  • Before executing linux-client, prepare for Device Initialization (DI) using SCT Manufacturer. Refer to DI SCT Setup. After the SCT Manufacturer is set up, execute the TPM make ready script. Refer to TPM Make Ready. Alternatively, perform the steps listed in section 7.1 to initialise the device without using TPM Make Ready script.

    Script execution command:

    $ ./tpm_make_ready_ecdsa.sh -p <SDO Client-SDK data folder location>

  • Once the TPM make ready script is executed successfully, the device is now initialized with the credentials and is ready for ownership transfer. To run the device against the SCT Manufacturer for the DI protocol, do the following:

    $ ./build/linux-client

  • To enable the device for owner transfer, configure the Rendezvous and IoT-Platform-SDK. Refer to Ownership Transfer Setup . After these servers are set up, execute linux-client again.

    $ ./build/linux-client

Note: If the linux-client was built with flag TPM2_TCTI_TYPE=tpmrm0, running the it along with tpm_make_ready_ecdsa.sh, may require elevated privileges. Please use 'sudo' to execute.

7.1 Prepare SDO Client SDK Data Folder

Persistent Storage Index in TPM

Find a persistent storage index that is unused in the TPM and note it down. It usually starts from 0x81000000. To see the indexes that are already being used, use the following command. SDO uses the 0x81000001 index for the following command examples.

 $ tpm2_getcap handles-persistent

Primary Key Generation from Endorsement Hierarchy

 $ tpm2_createprimary -C e -g sha256 -G ecc256:aes128cfb -c data/tpm_primary_key.ctx -V

Load the Primary Key into TPM Persistent Memory

 $ tpm2_evictcontrol -C o 0x81000001 -c data/tpm_primary_key.ctx -V

Device ECDSA Key-Pair Generation

 $ tpm2tss-genkey -a ecdsa -c nist_p256 data/tpm_ecdsa_priv_pub_blob.key -v -P 0x81000001

Generate Device MString

 $ export OPENSSL_ENGINES=/usr/local/lib/engines-1.1/; openssl req -new -engine tpm2tss -keyform engine -out data/device_mstring -key data/tpm_ecdsa_priv_pub_blob.key -subj "/CN=www.sdoDevice1.intel.com" -verbose; truncate -s -1 data/device_mstring; echo -n "13" > /tmp/m_string.txt; truncate -s +1 /tmp/m_string.txt; echo -n "intel-1234" >> /tmp/m_string.txt; truncate -s +1 /tmp/m_string.txt; echo -n "model-123456" >> /tmp/m_string.txt; truncate -s +1 /tmp/m_string.txt; cat data/device_mstring >> /tmp/m_string.txt; base64 -w 0 /tmp/m_string.txt > data/device_mstring; rm -f /tmp/m_string.txt

8. Troubleshooting Details

  • TPM Authorization Failure while Running tpm2-tools Command.
    Clear TPM from the BIOS. To run the TPM-based SDO implementation, the TPM on the device should not be owned. To reset the TPM, go to your device BIOS and clear the TPM. To find the location of the option in the BIOS of your device, refer to your device manual.

  • Clear the Used Persistent Index in TPM.
    Use the tpm2_evictcontrol command to delete the content or clear TPM from the BIOS. To run the TPM-based SDO implementation, the TPM on the device should not be owned. To reset the TPM, go to your device BIOS and clear the TPM. To find the location of the option in the BIOS of your device, refer to your device manual.

    Assuming that the index is 0x81000001, run the following command to delete the keys.

    $ tpm2_evictcontrol -C o -c 0x81000001 -V

  • OpenSSL* Toolkit Library Linking Related Error While Building SDO Client SDK.
    There is a dependency on the OpenSSL* toolkit version 1.1.1g for building and running the SDO Client SDK. Check the version of the OpenSSL toolkit installed in your machine with the command

    $ openssl version

    If the OpenSSL toolkit version in your machine is earlier than version 1.1.1g, follow the steps given in Section10 to update the OpenSSL version to 1.1.1g.

Steps to Upgrade the OpenSSL* Toolkit to Version 1.1.1g

# 1. If libssl-dev is installed, remove it:

  $ sudo apt-get remove --auto-remove libssl-dev
  $ sudo apt-get remove --auto-remove libssl-dev:i386

# 2. Pull the tarball: 

  $ wget https://www.openssl.org/source/openssl-1.1.1g.tar.gz

# 3. Unpack the tarball with 

  $ tar -zxf openssl-1.1.1g.tar.gz && cd openssl-1.1.1g

# 4. Issue the command 

  $ ./config

# 5. Issue the command 

  $ make 
  (You may need to run `sudo apt install make gcc` before running this command successfully).

# 6. Check for possible errors.

  $ make test

# 7. Backup the current OpenSSL binary

  $ sudo mv /usr/bin/openssl ~/tmp

# 8. Issue the command

  $ sudo make install

# 9. Create a symbolic link from the newly installed binary to the default location:

  $ sudo ln -s /usr/local/bin/openssl /usr/bin/openssl

# 10.  Run the command to update symlinks and rebuild the library cache.

  $ sudo ldconfig

# 11. Assuming no errors in executing steps 4 through 10, you should have successfully installed the new version of the OpenSSL toolkit.
# Issue the following command from the terminal:

  $ openssl version

  Your output should be as follows:

  OpenSSL 1.1.1g  31 Mar 2020