[Bug 1948598] [NEW] Can't unlock multiple devices in initramfs

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Niclas Morin (brydling):

[Impact] 
clevis can be used to automatically unlock LUKS-encrypted devices during boot by asking a remote server for the key (sort of). It does so by monitoring for the processes that send up the interactive prompts "Please unlock disk xxx:" and then sends a key to that process through a fifo that the process has opened.
The bug that existed in clevis versions prior to version 17 forgot to clear a saved PID-variable (used to store the PID of the process that creates the prompt for the user), so when the PID of the first process has been found it won't look for more processes of this type. This means it can only unlock one device. If you have for example some sort of RAID root filesystem with multiple disks (or a ZFS mirror as me) then clevis does not work at all.

[Test Plan]
- Setup a tang server on a different host:
# sudo apt install tang
# sudo systemctl enable tangd.socket --now
# reboot

- Setup two LUKS-disks that shall be decrypted during early boot (append
option initramfs to them in /etc/crypttab)

- Setup clevis:
# sudo apt install clevis
# sudo apt install clevis-luks
# sudo apt install clevis-initramfs

- Bind the encrypted disks to the tang server:
# sudo clevis luks bind -d /dev/<disk1> tang '{"url": "http://<tang-server>"}'
# sudo clevis luks bind -d /dev/<disk2> tang '{"url": "http://<tang-server>"}'

- Regenerate initramfs
# sudo update-initramfs -u -k 'all'

- Reboot
# reboot

After the reboot you will be stuck at "Please unlock disk xxx:" until
you enter the passphrase manually.

If you perform all the steps using only one disk it will work.

[Where problems could occur]
If something is wrong with the patch it will show up when clevis is unlocking a LUKS-encrypted disk during initramfs.

[Other Info]
This has been fixed in upstream (latchset/clevis, version 17, commit 0abdfbc7812c8ef588ee22fd35941b5e831fdce7)

** Affects: clevis (Ubuntu)
     Importance: Undecided
         Status: Fix Committed

** Affects: clevis (Ubuntu Focal)
     Importance: Undecided
         Status: New

** Affects: clevis (Ubuntu Hirsute)
     Importance: Undecided
         Status: New

** Affects: clevis (Ubuntu Impish)
     Importance: Undecided
         Status: New

** Affects: clevis (Ubuntu Jammy)
     Importance: Undecided
         Status: Fix Committed

-- 
Can't unlock multiple devices in initramfs
https://bugs.launchpad.net/bugs/1948598
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