Simple GUI for unlocking cryptsetup volumes
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Latest commit 4ca5f52 Jul 15, 2018

README.md

cryptsetup-gui is a fairly simple application for unlocking and mounting LUKS paritions with a GUI. The intended use is for mounting an encrypted home partition after login, but it can be used for any encrypted partition.

It is invoked with the name of an encrypted partition, looks up that name in /etc/crypttab to find the device, prompts the user for a password, decrypts the device and mounts it according to /etc/fstab.

Mounting /home on login

In order to enable the mounting of /home AFTER a user has logged in, we employ a little trick:

  1. The user's home directory is still set to /home/#username#.
  2. We create this directory when /home is unmounted
  3. We add a .xinitrc file that calls cryptsetup-gui, mounts /home on top of us, and then executes the "real" user .xinitrc

The included xinitrc file should take care of this, and is installed into /etc/skel. It defaults to the name of the encrypted home partition to be chome, but this can be changed by modifying the file after copying it to your unmounted home directory.

Security

Note: The binary cryptsetup-gui installed into /usr/bin has the setuid flag enabled and is owned by root. This is so that it can be invoked by users and still be permitted to unlock a device. This is done on your own risk!

The application only accepts a single parameter, the name of the encrypted device, and this is enforced to be only a-z. Thus, I do not believe there to be any risk of that causing a security risk with setuid. The file does execute two shell commands using cryptsetup and luks, however the parameters for these are read from /etc/crypttab and /etc/fstab. Thus, should a malicious user be able to modify either of these files, he/she will be able to use cryptsetup-gui to run arbitrary commands as root. That said, if they can edit those files, you already have a security breach.

License

It's the standard MIT license.

Copyright (C) 2012 Jon Gjengset

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.