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mkinitramfs/README.rst
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mkinitramfs
===========
Simple script for generating initramfs for the encrypted root disks.
Usage
-----
- Create encrypted disk or partition using `cryptsetup`_
- Create ``~/.config/mkinitramfs.toml`` file with similar content to:
.. code:: toml
[name]
uuid = "disk-uuid"
key = "key-filename"
...
where every entry have disk name (**name** in this case), which have at least
two attributes - disk/partition UUID and key filename.
- Provide a key file for the disk/partition. Assumption is, that it is an
encrypted file using `ccrypt`_ instead of plain file or password protected
luks. Keys will be looked using provided path, i.e.
.. code:: toml
[laptop]
uuid = "88b99002-028f-4744-94e7-45e4580e2ddd"
key = "/full/path/to/the/laptop.key"
[desktop]
uuid = "23e31327-1411-491c-ab00-c36f74c441f1"
key = "desktop.key"
[pendrive]
uuid = "1453a45e-ca3f-4d39-8fd7-a6a96873c25c"
key = "../pendrive.key"
so yes - it is possible to use key file in absolute or relative paths. If no
key will be found, it's been looking for in path specified by
``--key-path | -k`` parameter, which by default is in
``$XDG_DATA_HOME/keys`` (usually it will be ``~/.local/share/keys``).
- Move ``mkinitramfs.py`` script to some location in your ``$PATH`` (like
``~/bin``)
- Invoke ``mkinitramfs.py`` script:
.. code:: shell-session
# mkinitramfs.py laptop
that command will generate initramfs, copy key, and make appropriate change
in ``init`` script and compress it with ``cpio``.
Using ``--install | -i`` parameter, initramfs will be automatically installed
on ``/boot`` with appropriate links. Note, that old images (they have
``.old`` suffix in the filename) will be removed in that case.
Configuration
-------------
Other than key path and device UUID, configuration can hold additional options
similar to those passed via commandline. Consider following example:
.. code:: toml
[laptop]
uuid = "88b99002-028f-4744-94e7-45e4580e2ddd"
key_path = "/full/path/to/the/keys/dir"
key = "laptop.key"
yubikey = true
dropbear = true
ip = '192.168.0.1'
gateway = '192.168.0.254'
netmask = '24'
authorized_keys = "/full/path/to/the/.ssh/authorized_keys"
This will inform mkinitramfs script, that dropbear and yubikey features are
enabled. Also for network related configuration, there are last three options.
The complete list of supported options is listed below:
- ``copy_modules``
- ``no_key``
- ``key_path``
- ``key``
- ``disk_label``
- ``sdcard``
- ``yubikey``
- ``dropbear``
Using key devices
-----------------
It is possible to use an SD card (if computer does have reader built-in) or old
plain USB pendrive. Currently support for the keys is limited to 4096 bytes,
and assumption that key is unencrypted - it helps with booting system
non-interactively.
Yubikey
-------
There is possibility for using key which is encrypted using response from
challenge response using `ykchalresp`_ command. The challenge here could be
any string, so the name of the device from config is used.
.. _ccrypt: https://sourceforge.net/projects/ccrypt/
.. _cryptsetup: https://gitlab.com/cryptsetup/cryptsetup/blob/master/README.md
.. _ykchalresp: https://github.com/Yubico/yubikey-personalization