[Bug 1837437] [NEW] disk content permanently lost when changing LUKS password

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Olivier Tilloy (osomon):

[Impact]

Users with full disk encryption trying to change the encryption
passphrase in gnome-disks will get an error message, and after rebooting
neither the old passphrase nor the new one can unlock their disk,
rendering the machine unusable.


[Test Case]

(can be done in a virtual machine, for testing purposes)
1. Download a 19.04 ISO, and install it, choosing the full disk encryption option
2. When rebooting after the installation is complete, you are prompted for your passphrase to unlock the disk
3. Once logged in, open gnome-disks, select the encrypted disk and click the contextual action to change the encryption passphrase
4. Enter your old passphrase and the new one (twice), as prompted, then click OK

Expected result: the passphrase is changed successfully, and when
rebooting the new passphrase can unlock the disk

Current result: changing the passphrase fails, the user is presented
with an error message ("Error changing passphrase on device /dev/sda5:
Failed to add the new passphrase: Invalid argument (udisks-error-quark,
0)"), and when rebooting neither the old passphrase nor the new one can
unlock the disk, which renders it unusable

To test the fix, the updated libblockdev* packages need to be installed
on the machine before attempting to change the encryption passphrase in
gnome-disks.


[Regression Potential]

The patch only touches code related to changing the LUKS encryption passphrase, so non-encrypted disk setups should not be affected.
Scenarii with full-disk encryption should be carefully tested, including changing an existing passphrase, adding and removing passphrases, both from the gnome-disks UI and using the cryptsetup CLI.


[Original Description]

This is fixed upstream. Logging this bug to track the fix in to Ubuntu.

>From the upstream bug:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=928893

Dear Maintainer,

   * What led up to the situation?

Install system using normal full disk encryption LUKS+Ext4.
After install open gnome-disk-utility and change
encryption password. It gives some error dialog and
now you are royally screwed. It deleted the only
LUKS keyslot. Cannot add new keyslots because of that.
All data will be lost after reboot.

Here is output of luksdump:

udo cryptsetup luksDump /dev/sda5
LUKS header information
Version: 2
Epoch: 4
Metadata area: 16384 [bytes]
Keyslots area: 16744448 [bytes]
UUID: 3c16ad4c-294c-4547-bf3e-bb8864ba5ea3
Label: (no label)
Subsystem: (no subsystem)
Flags: (no flags)

Data segments:
  0: crypt
        offset: 16777216 [bytes]
        length: (whole device)
        cipher: aes-xts-plain64
        sector: 512 [bytes]

Keyslots:
Tokens:
Digests:
  0: pbkdf2
        Hash: sha256
        Iterations: 59904
        Salt: XX XX XX XX XX ....
        Digest: XX XX XX XX XX ...

----------------------------------------

I changed salt and digest. No Keyslots are present!!!

I tried this 2 times in a row with new install,
exactly same result.

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.0.8-xanmod5 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=ru_RU.UTF-8, LC_CTYPE=ru_RU.UTF-8 (charmap=UTF-8), LANGUAGE=ru_RU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gnome-disk-utility depends on:
ii dconf-gsettings-backend [gsettings-backend] 0.30.1-2
ii libatk1.0-0 2.30.0-2
ii libc6 2.28-10
ii libcairo2 1.16.0-4
ii libcanberra-gtk3-0 0.30-7
ii libdvdread4 6.0.1-1
ii libgdk-pixbuf2.0-0 2.38.1+dfsg-1
ii libglib2.0-0 2.58.3-1
ii libgtk-3-0 3.24.5-1
ii liblzma5 5.2.4-1
ii libnotify4 0.7.7-4
ii libpango-1.0-0 1.42.4-6
ii libpangocairo-1.0-0 1.42.4-6
ii libpwquality1 1.4.0-3
ii libsecret-1-0 0.18.7-1
ii libsystemd0 241-3
ii libudisks2-0 2.8.1-4
ii udisks2 2.8.1-4

gnome-disk-utility recommends no packages.

gnome-disk-utility suggests no packages.

-- no debconf information

** Affects: libblockdev (Ubuntu)
     Importance: Undecided
         Status: Fix Released

** Affects: libblockdev (Ubuntu Disco)
     Importance: Undecided
     Assignee: Olivier Tilloy (osomon)
         Status: Confirmed

** Affects: gnome-disk-utility (Debian)
     Importance: Unknown
         Status: Unknown

-- 
disk content permanently lost when changing LUKS password
https://bugs.launchpad.net/bugs/1837437
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