vuinputd

A minimal CUSE-based proxy for /dev/uinput that lets unmodified applications (like Sunshine) run inside a container while creating virtual input devices on the host.

Overview

This project makes it possible to run Sunshine inside systemd-nspawn containers without breaking input isolation.

Normally, Sunshine creates virtual input devices via /dev/uinput. If /dev/uinput is simply bind-mounted into a container:

• Devices from one container can leak into another.
• Keyboards and mice may attach to host seats that are attached to a running session.

This project solves that by introducing a mediated input stack:

• A fake /dev/uinput inside the container.
• A daemon that forward add/remove events into the container, making SDL2 and Wayland/libinput behave correctly.
• A host proxy that safely creates the real devices.
• udev rules that tag and isolate devices per-container.

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Architecture

• Container: Sunshine writes to fake /dev/uinput.
• Host Proxy: Creates real devices on the host, labeled with container identity Forwards add/remove events into the container, so SDL2 and Wayland see devices natively.
• udev: Matches by identity, prevents host use.

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Benefits

• 🎮 SDL2 / Wayland compatibility: fake-udev ensures compositors and games see device events properly.
• 🔒 Isolation: containers only see their own devices; host also sees them, but ignores them completely.
• ♻️ Lifecycle safety: devices are removed cleanly when Sunshine stops.
• 🛠️ Simple integration: no kernel patches, just userspace tools + udev rules.

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Documentation

See docs/DESIGN.md for detailed architecture, design tradeoffs, and security considerations.

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License

MIT