Wlproxy

Wayland socket proxy that can do minor changes to messages for any programs that use its downstream socket.

This allows you to do things like create a proxy Wayland socket to mount in a container and write compositor decoration rules that are specific to the container windows.

Features

• Replace or prefix app_id - this can help writing compositor rules targeting programs running on a wlproxy instance.
• Replace or prefix title - this may be helpful if nesting compositors, since compositors don't expect their title to be used and don't set useful titles.
• Block specific Wayland interfaces by name - prevents the client from binding to any of the listed interfaces. Blocked global events are silently dropped before reaching the client, and the client's bind requests for these interfaces are intercepted. This can be used to restrict access to capabilities like screenshots (zwlr_screencopy_manager_v1), clipboard (ext_data_control_manager_v1, zwlr_data_control_device_v1), layer shell (zwlr_layer_shell_v1), and others.

Installation

From source

cargo install wlproxy

Pre-built binary

cargo binstall wlproxy

Or download a pre-built binary from the releases page.

Usage

Usage: wlproxy [OPTIONS] <DOWNSTREAM>

Arguments:
  <DOWNSTREAM>  Full path for the new Wayland socket

Options:
  -u, --upstream <UPSTREAM>  Full path to compositor Wayland socket
  -a, --app-id <APP_ID>      Force all xdg toplevels to have the same app id
  -A, --prefix-app-id        Prefix the app id instead of replacing
  -t, --title <TITLE>        Force all xdg toplevels to have the same title
  -T, --prefix-title         Prefix the title instead of replacing
  -b, --block <BLOCK>        Wayland interfaces to block (can be specified multiple times)
  -q, --quiet                Suppress warnings about unknown interface names
      --debug                Print debug messages
  -h, --help                 Print help

Basic passthrough

wlproxy /run/user/1000/wayland-filtered
WAYLAND_DISPLAY=wayland-filtered my-app

The --upstream flag is optional and defaults to $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY (or $XDG_RUNTIME_DIR/wayland-0).

Replace app_id

wlproxy /run/user/1000/wayland-filtered --app-id org.example.testid

Prefix app_id

wlproxy /run/user/1000/wayland-filtered --app-id pfx- --prefix-app-id

Block privacy-sensitive interfaces

When running untrusted applications (e.g. in a container or Flatpak), you can block Wayland interfaces that could leak sensitive data or compromise the user's session:

wlproxy /run/user/1000/wayland-filtered \
    --block zwlr_screencopy_manager_v1 \
    --block zkde_screencast_unstable_v1 \
    --block ext_data_control_manager_v1 \
    --block zwlr_data_control_manager_v1 \
    --block zwlr_virtual_pointer_manager_v1 \
    --block zwp_virtual_keyboard_manager_v1

This blocks the following capabilities:

Interface	Risk
zwlr_screencopy_manager_v1 / zkde_screencast_unstable_v1	Screen capture
ext_data_control_manager_v1 / zwlr_data_control_manager_v1	Clipboard access
zwlr_virtual_pointer_manager_v1 / zwp_virtual_keyboard_manager_v1	Input injection

The --quiet flag suppresses warnings about unknown interface names (useful when listing interfaces that require specific compositor support).

Acknowledgements

This project is a fork of andrewbaxter/filterway, licensed under ISC.

I'm grateful to Andrew Baxter for the original implementation and inspiration. The original project appears to be inactive, and since I needed to introduce substantial changes, a separate project fork proved to be a better fit than a pull request workflow. The original author's code remains under the ISC license.