Exploring the Embedded Controller

TomsonTom · June 24, 2024, 10:40am

Thank you @DHowett ! Great work on that repo, happy to see it mirrored on GitHub!

Here is the pull request for WinRing0 with Secure Boot:

github.com/DHowett/ectool

Add support for Secure Boot on Windows by adding the WinRing0 interface

DHowett:main ← tomasiser:winring0

opened 10:39AM - 24 Jun 24 UTC

tomasiser

+397 -2

Hi there! This PR allows users to run ectool on **Windows with Secure Boot en…abled** as shown on the following screenshot: ![image](https://github.com/DHowett/ectool/assets/10374559/77ee08ec-df5c-45d7-8541-ae3d49a0d553) ## User manual To run `ectool` with Secure Boot enabled, you have to do the following: - You have to [download](https://github.com/LibreHardwareMonitor/LibreHardwareMonitor/releases) and start [Libre Hardware Monitor](https://github.com/LibreHardwareMonitor/LibreHardwareMonitor) (LHM). Remember that LHM needs to keep running in the background so that `ectool` can access the WinRing0 driver that is properly signed and embedded in LHM. - You have to execute `ectool` **with admin privileges** and with the `--interface=winring0` argument. **Example:** To run the `battery` command, you have to execute the application as follows: ``` ectool.exe --interface=winring0 battery ``` ## Developer manual In order to pass Secure Boot, we need a properly signed driver that can communicate with the embedded controller (EC). But signing a custom Windows driver is expensive and complicated (there is a whole subdiscussion about it [on the Framework forums](https://community.frame.work/t/exploring-the-embedded-controller/12846)). As a workaround, I figured that we could use an existing driver that was signed a long time ago and still passes Microsoft's strict signing policies, which is exactly what **WinRing0** is. Just beware that the driver is very powerful and: - I don't like downloading random drivers from random internet sources that can be full of viruses. - Some antivirus software does not like WinRing0. For these reasons, I believe the best we can do is to **not embed WinRing0 in here** and instead rely on [Libre Hardware Monitor](https://github.com/LibreHardwareMonitor/LibreHardwareMonitor) (LHM), which is a trusted software that is doing all sorts of tricks to bypass some antivirus software (for example, by modifying the bits in the embedded archive that contains WinRing0 so that it is undetected by the antivirus). To use WinRing0, I basically copy-pasted the `comm-lpc.cc` code into a `comm-winring0.cc` file that now contains a helper class for communicating with the driver. I also needed to modify parts of the file so that it compiles on Windows (e.g., by using `std::this_thread::sleep_for` instead of `usleep`). The helper class is called `WinRing0PortInputOutput`, it's at the top of the `comm-winring0.cc` file, and the API is straightforward. I wrote the class by reverse engineering LHM and checking how they communicate with the driver. All the magic is in the `read_byte` and `write_byte` methods that use `DeviceIoControl` for communication. ### Notes for compiling on Windows: Something to keep in mind is that the current version of ectool can only be compiled with Clang, so if you want to compile via Visual Studio, you have to first install the clang toolset and set it in your CMakeSettings.json via Visual Studio. Also, I had some troubles with an include file (`win32_shim.h`), so I also commited a fix for that in `CMakeLists.txt`. ## Known issues I randomly found out that the `powerinfo` command does not work. Currently I am unsure if it has anything to do with WinRing0.

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Exploring the Embedded Controller

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