From: Eddie James Date: Tue, 24 Oct 2023 15:43:52 +0000 (-0500) Subject: doc: Add measured boot documentation X-Git-Url: http://git.dujemihanovic.xyz/?a=commitdiff_plain;h=450afc350cd306e800f97baee0fbcaa0d1e8df80;p=u-boot.git doc: Add measured boot documentation Briefly describe the feature and specify the requirements. Signed-off-by: Eddie James Reviewed-by: Simon Glass Reviewed-by: Ilias Apalodimas Signed-off-by: Ilias Apalodimas --- diff --git a/doc/usage/index.rst b/doc/usage/index.rst index fa702920fa..fb043a8923 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -14,6 +14,7 @@ Use U-Boot partitions cmdline semihosting + measured_boot Shell commands -------------- diff --git a/doc/usage/measured_boot.rst b/doc/usage/measured_boot.rst new file mode 100644 index 0000000000..0aad590859 --- /dev/null +++ b/doc/usage/measured_boot.rst @@ -0,0 +1,31 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Measured Boot +===================== + +U-Boot can perform a measured boot, the process of hashing various components +of the boot process, extending the results in the TPM and logging the +component's measurement in memory for the operating system to consume. + +By default, U-Boot will measure the operating system (linux) image, the +initrd image, and the "bootargs" environment variable. By enabling +CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image. + +The operating system typically would verify that the hashes found in the +TPM PCRs match the contents of the event log. This can further be checked +against the hash results of previous boots. + +Requirements +--------------------- + +* A hardware TPM 2.0 supported by the U-Boot drivers +* CONFIG_TPM=y +* CONFIG_MEASURED_BOOT=y +* Device-tree configuration of the TPM device to specify the memory area + for event logging. The TPM device node must either contain a phandle to + a reserved memory region or "linux,sml-base" and "linux,sml-size" + indicating the address and size of the memory region. An example can be + found in arch/sandbox/dts/test.dts +* The operating system must also be configured to use the memory regions + specified in the U-Boot device-tree in order to make use of the event + log.