systemd-password-agent

Deprecation Notice: with "ask-password" caching implemented as of systemd-227 (2015-10-07), there's likely no reason to use this tool, as such in-kernel caching seem to be a better alternative, but likely requires systemd running in initramfs.

Python implementation of systemd password agent interface.

Honest to $DEITY implementation of the interface in form of python script (for ease of hackability), with all the inotify, timestamp, policykit goodies and checks.

Needs python2.7 implementation with ctypes support (vanilla cpython will do).

Usage

• Clone.

• Copy the py script to some more-or-less stable path (like /usr/local/bin/systemd_password_cache, just make sure it matches what's in the .service files).

• Override get_pass() function in the script with whatever you need to get the password, like:

    def get_pass():
      cache_path = '/run/initramfs/.password.cache'
      try: return open(cache_path, 'rb').read().strip()
      except (OSError, IOError): raise SkipRequest
  

• Install .service file to run the thing to some /etc/systemd/system path and enable it. Also skim through it and correct paths and requirements maybe.

Example usage (for which these scripts/services were actually written) - caching of passphrase (or hardware-generated key) for encrypted (dm-crypt) disks with dracut/systemd. Idea is to use RSA key on a smartcard token to produce key for dm-crypt (or just cache what is entered interactively, as plymouth does), then use it repeatedly for every encrypted lvm partition systemd tries to unlock, not just root.

(more info on how this particular setup works can be found here)