breakglass is a gokrazy package which provides emergency/debugging access to a gokrazy installation.
It breaks the gokrazy model in that it allows you to run payloads implemented in any language (e.g. busybox, implemented in C).
To repeat, breakglass’s whole idea is remote code execution (via SSH/SCP, listening only on private network addresss). Hence, it should usually not be present on your gokrazy installation, but it might be useful for development/debugging. As a safety measure, breakglass will not automatically be started on boot, but needs to explicitly be started via the gokrazy web interface.
Please see https://gokrazy.org/quickstart/ if you’re unfamiliar with gokrazy.
First, install your SSH public key(s) as authorized via package
config for the
mkdir -p extrafiles/github.com/gokrazy/breakglass/etc/ # Note: At the moment only ed25519 and ecdsa keys work cat ~/.ssh/id_*.pub \ > extrafiles/github.com/gokrazy/breakglass/etc/breakglass.authorized_keys mkdir -p flags/github.com/gokrazy/breakglass/ echo '-authorized_keys=/etc/breakglass.authorized_keys' \ > flags/github.com/gokrazy/breakglass/flags.txt
Then, add the
github.com/gokrazy/serial-busybox packages to your
gokr-packer -overwrite=/dev/sdx \ github.com/gokrazy/hello \ github.com/gokrazy/serial-busybox \ github.com/gokrazy/breakglass
Be sure to install the convenience SSH wrapper tool on the host:
go install github.com/gokrazy/breakglass/cmd/breakglass
Start a shell
If you have
github.com/gokrazy/serial-busybox installed on your gokrazy
installation, you can directly start a shell without having to upload your own
If you prefer, you can also manually start
breakglass in the gokrazy web
interface and then use
ssh gokrazy to log in.
Run your own tools
- Create a tarball containing your statically linked arm64 binaries and any other files you’ll need.
- SCP that tarball to your gokrazy installation, where breakglass will unpack it into a temporary directory.
- Execute a binary via SSH.
Here’s an example, assuming you unpacked and statically cross-compiled
/tmp/busybox-1.22.0 and your gokrazy installation runs on
$ cd /tmp/busybox-1.22.0 $ file busybox busybox: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, for GNU/Linux 3.7.0, BuildID[sha1]=c9e20e9849ed0ca3c2bd058427ac31a27c008efe, stripped $ ln -s busybox sh $ tar cf breakglass.tar --dereference sh $ breakglass -debug_tarball_pattern=debug.tar gokrazy /tmp/breakglass564067692 # df -h Filesystem Size Used Available Use% Mounted on /dev/root 60.5M 60.5M 0 100% / devtmpfs 445.3M 0 445.3M 0% /dev tmpfs 50.0M 1.8M 48.2M 4% /tmp tmpfs 1.0M 8.0K 1016.0K 1% /etc /dev/mmcblk0p4 28.2G 44.1M 26.7G 0% /perm