chromebrew / crew-sudo

Workaround for using sudo on ChromeOS crosh shell (ChromeOS v117+)

crew-sudo

Make sudo "works" on ChromeOS crosh shell (ChromeOS v117+) by redirecting sudo calls to VT-2 shell

Background

On ChromeOS v117, all Chrome-related processes (e.g. the ChromeOS UI) is executed with the NO_NEW_PRIVS bit, which means:

• suid/sgid-bit is blocked, and thus no more sudo
• This flag will be inherited by its subprocess (including crosh) and cannot be unset

That benefits security. However, it is bad for Crouton/Chromebrew users.

The official workaround for this is using the VT-2 shell (aka frecon) ¹, but frecon just sucks:

• No clipboard support
• No Caps Lock support
• No HiDPI support
• Poor compatibility with TUI programs

So does there a way to call sudo in crosh but run it in VT-2? That's what this project does :)

How it works?

It works in a similar way compared with popular Android root solutions like Magisk or SuperSU. It is divided into 2 parts:

• A sudo server running in VT-2 for executing sudo requests from crosh
• A sudo client for sending sudo requests to the server from crosh

All communication between the sudo server and client is done via Unix socket.

Usage

All you need to do is start the crew-sudo daemon in VT-2 and sudo will work again in crosh :)

sudo <command to execute or sudo options>
---
crew-sudo [command] <options>
crew-sudo -h|--help
crew-sudo -V|--version

Command	Description
client	Run as client mode, pass all given command arguments to daemon
daemon	Run as daemon mode, listen incoming requests at /tmp/crew-sudo.socket
stop-daemon	Stop currently running crew-sudo daemon

---

Options	Description
--bashrc	Suppress daemon is already running error
--foreground	Run crew-sudo daemon in foreground
--replace	Replace the currently running crew-sudo daemon

What works currently

• Send terminal input to command/send command output back to crosh
• Handle terminal size events
• Sync exit code

License

Copyright (C) 2013-2024 Chromebrew Authors

This project including all of its source files is released under the terms of GNU General Public License (version 3 or later).

Footnotes

1. sudo works in VT-2 because the VT-2 process is independent of the browser process and executed without the NO_NEW_PRIVS bit ↩