This is a helper script to manage removable crypto disks on a Linux host for backup purposes. The idea is to run the script and mount available crypto disks and to unmount them if they are not needed for operation or when disks are moved to an offsite location.

Usage

To mount attached disks run:

$ manage_crypto_disks.sh mount

To unmount them run:

$ manage_crypto_disks.sh unmount

For example when you know you rotate disks Fridays, you could unmount disks from you backup script or from cron and then power them off using the "poweroff" option:

$ manage_crypto_disks.sh poweroff

Devices are configured in a config file. This config file stores the disk's UUIDs, a mount point name and the LUKS passphrase. If you do not want to store LUKS passphrases in the config file, you could enter a dash ('-'). Then the script will prompt for a passphrase. An example is shown below:

bc686425-53e6-4d7e-a51a-f47bcdac1bdb	backup_21	-
9fc10fb6-ab53-4262-8ea8-250be2c7783a	backup_22	-
809a092e-65a2-4ee7-982d-a680deadbeef	backup_23	secretsecret
120c888f-596b-4479-ac9d-53cd9969ad15	backup_24	anotherpassphrase

You could specify the config file as parameter:

$ manage_crypto_disks.sh mount disk_set_2.dat

Security considerations

LUKS passphrases might be stored in a config file on the system. Users with elevated privileges may access the config file and will be able to read the passphrases.

Furthermore, an attacker may get physical access to the disk that stores the config file and is able to read the passphrase as long as the system disk is not encrypted. Therefore, it is recommended to use an encrypted system disk.

Recommendations:

• Properly check file permissions of the config file. The script does another check, but if the script is never run, you will not see the warning.
• If you store passphrases, then better encrypt the file system where the config is stored.
• You may encrypt you backup too to reduce the impact when the LUKS passphrase leaks.
• You could avoid storing the passphrase and enter it manually by using the '-' in the password field.
• If you need the config frequently on the system, you could store the config file in a temp file system. Then it vanishes on power-down, but it will not prevent local privileged users from accessing it.

License

The script is published under a BSD license with a non-military clause. Please read the details in the file LICENSE that is included in this repository.