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| -rw-r--r-- | docs/components/spd/optee-dispatcher.rst | 31 |
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diff --git a/docs/components/spd/optee-dispatcher.rst b/docs/components/spd/optee-dispatcher.rst new file mode 100644 index 0000000..81476f1 --- /dev/null +++ b/docs/components/spd/optee-dispatcher.rst @@ -0,0 +1,31 @@ +OP-TEE Dispatcher +================= + +`OP-TEE OS`_ is a Trusted OS running as Secure EL1. + +To build and execute OP-TEE follow the instructions at +`OP-TEE build.git`_ + +There are two different modes for loading the OP-TEE OS. The default mode will +load it as the BL32 payload during boot, and is the recommended technique for +platforms to use. There is also another technique that will load OP-TEE OS after +boot via an SMC call by enabling the option for OPTEE_ALLOW_SMC_LOAD that was +specifically added for ChromeOS. Loading OP-TEE via an SMC call may be insecure +depending upon the platform configuration. If using that option, be sure to +understand the risks involved with allowing the Trusted OS to be loaded this +way. ChromeOS uses a boot flow where it verifies the signature of the firmware +before executing it, and then only if the signature is valid will the 'secrets' +used by the TEE become accessible. The firmware then verifies the signature of +the kernel using depthcharge, and the kernel verifies the rootfs using +dm-verity. The SMC call to load OP-TEE is then invoked immediately after the +kernel finishes loading and before any attack vectors can be opened up by +mounting writable filesystems or opening network/device connections. this +ensures the platform is 'closed' and running signed code through the point where +OP-TEE is loaded. + +-------------- + +*Copyright (c) 2014-2023, Arm Limited and Contributors. All rights reserved.* + +.. _OP-TEE OS: https://github.com/OP-TEE/build +.. _OP-TEE build.git: https://github.com/OP-TEE/build |