1Building FIP images with support for Trusted Board Boot 2======================================================= 3 4Trusted Board Boot primarily consists of the following two features: 5 6- Image Authentication, described in :ref:`Trusted Board Boot`, and 7- Firmware Update, described in :ref:`Firmware Update (FWU)` 8 9The following steps should be followed to build FIP and (optionally) FWU_FIP 10images with support for these features: 11 12#. Fulfill the dependencies of the ``mbedtls`` cryptographic and image parser 13 modules by checking out a recent version of the `mbed TLS Repository`_. It 14 is important to use a version that is compatible with TF-A and fixes any 15 known security vulnerabilities. See `mbed TLS Security Center`_ for more 16 information. See the :ref:`Prerequisites` document for the appropriate 17 version of mbed TLS to use. 18 19 The ``drivers/auth/mbedtls/mbedtls_*.mk`` files contain the list of mbed TLS 20 source files the modules depend upon. 21 ``include/drivers/auth/mbedtls/mbedtls_config.h`` contains the configuration 22 options required to build the mbed TLS sources. 23 24 Note that the mbed TLS library is licensed under the Apache version 2.0 25 license. Using mbed TLS source code will affect the licensing of TF-A 26 binaries that are built using this library. 27 28#. To build the FIP image, ensure the following command line variables are set 29 while invoking ``make`` to build TF-A: 30 31 - ``MBEDTLS_DIR=<path of the directory containing mbed TLS sources>`` 32 - ``TRUSTED_BOARD_BOOT=1`` 33 - ``GENERATE_COT=1`` 34 35 In the case of Arm platforms, the location of the ROTPK hash must also be 36 specified at build time. The following locations are currently supported (see 37 ``ARM_ROTPK_LOCATION`` build option): 38 39 - ``ARM_ROTPK_LOCATION=regs``: the ROTPK hash is obtained from the Trusted 40 root-key storage registers present in the platform. On Juno, this 41 registers are read-only. On FVP Base and Cortex models, the registers 42 are read-only, but the value can be specified using the command line 43 option ``bp.trusted_key_storage.public_key`` when launching the model. 44 On Juno board, the default value corresponds to an ECDSA-SECP256R1 public 45 key hash, whose private part is not currently available. 46 47 - ``ARM_ROTPK_LOCATION=devel_rsa``: use the default hash located in 48 plat/arm/board/common/rotpk/arm_rotpk_rsa_sha256.bin. Enforce generation 49 of the new hash if ROT_KEY is specified. 50 51 - ``ARM_ROTPK_LOCATION=devel_ecdsa``: use the default hash located in 52 plat/arm/board/common/rotpk/arm_rotpk_ecdsa_sha256.bin. Enforce generation 53 of the new hash if ROT_KEY is specified. 54 55 Example of command line using RSA development keys: 56 57 .. code:: shell 58 59 MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \ 60 make PLAT=<platform> TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 \ 61 ARM_ROTPK_LOCATION=devel_rsa \ 62 ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem \ 63 BL33=<path-to>/<bl33_image> \ 64 all fip 65 66 The result of this build will be the bl1.bin and the fip.bin binaries. This 67 FIP will include the certificates corresponding to the Chain of Trust 68 described in the TBBR-client document. These certificates can also be found 69 in the output build directory. 70 71#. The optional FWU_FIP contains any additional images to be loaded from 72 Non-Volatile storage during the :ref:`Firmware Update (FWU)` process. To build the 73 FWU_FIP, any FWU images required by the platform must be specified on the 74 command line. On Arm development platforms like Juno, these are: 75 76 - NS_BL2U. The AP non-secure Firmware Updater image. 77 - SCP_BL2U. The SCP Firmware Update Configuration image. 78 79 Example of Juno command line for generating both ``fwu`` and ``fwu_fip`` 80 targets using RSA development: 81 82 :: 83 84 MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \ 85 make PLAT=juno TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 \ 86 ARM_ROTPK_LOCATION=devel_rsa \ 87 ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem \ 88 BL33=<path-to>/<bl33_image> \ 89 SCP_BL2=<path-to>/<scp_bl2_image> \ 90 SCP_BL2U=<path-to>/<scp_bl2u_image> \ 91 NS_BL2U=<path-to>/<ns_bl2u_image> \ 92 all fip fwu_fip 93 94 .. note:: 95 The BL2U image will be built by default and added to the FWU_FIP. 96 The user may override this by adding ``BL2U=<path-to>/<bl2u_image>`` 97 to the command line above. 98 99 .. note:: 100 Building and installing the non-secure and SCP FWU images (NS_BL1U, 101 NS_BL2U and SCP_BL2U) is outside the scope of this document. 102 103 The result of this build will be bl1.bin, fip.bin and fwu_fip.bin binaries. 104 Both the FIP and FWU_FIP will include the certificates corresponding to the 105 Chain of Trust described in the TBBR-client document. These certificates 106 can also be found in the output build directory. 107 108-------------- 109 110*Copyright (c) 2019-2020, Arm Limited. All rights reserved.* 111 112.. _mbed TLS Repository: https://github.com/ARMmbed/mbedtls.git 113.. _mbed TLS Security Center: https://tls.mbed.org/security 114