udev-hid-bpf

An automatic HID-BPF loader based on udev events. This repository aims to provide a simple way for users to write a HID-BPF program that fixes their device.

Note that the udev-hid-bpf repository contains there distinct components:

• udev-hid-bpf the binary that loads HID-BPF programs

• A set of HID-BPF programs (see the src/bpf directory)

• Scaffolding to automate loading of HID-BPF programs via udev.

See How it works for details on how everything fits together.

This project is written in Rust but knowledge of Rust should not be required, it is only used for scaffolding. Users intending to write a HID-BPF program do not need to edit the Rust code and the resulting BPF programs have no Rust dependencies.

The BPF programs themselves are in C.

Project home page

udev-hid-bpf is hosted on https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/

To file an issue please go to our issue tracker.

License

udev-hid-bpf is licensed under the GPL-2.0-only license.

Contents:

• How it works
  • How HID-BPF works
  • How udev-hid-bpf works
• Installing BPFs from our CI
  • Downloading and installing pre-compiled packages
  • Finding previous artifacts
• Getting started
  • Dependencies
  • Building all files
  • Install all files
  • Install a specific bpf.o file only
  • Running the BPF program
• Tutorial
  • Identifying the device
  • Scaffolding
  • Probing
  • Modifying the HID Reports
  • Modifying the HID Report Descriptor
  • Bringing it all together
• Filename conventions
  • Versioning files
  • Vendor and Product naming guidelines
• Quirks, user hacks, testing and stable
  • Installing testing or stable
  • Installing individual HID-BPF programs
  • Rebuilding
• Matching BPF programs to a device
  • Manual loading
  • Metadata in the HID-BPF sources (modalias matches)
  • Sharing the same BPF program for different devices
  • Run-time probe
• HID-BPF metadata
  • Overview
  • How this is interpreted?
• Handling udev properties in BPF programs
  • Reading udev properties into a BPF
  • Passing udev properties via the commandline
• HID Report Descriptor Macros
  • Enforcing the right HID Report size
• Other Resources