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

[dann frazier]

@brydling: I uploaded a test clevis build to
https://launchpad.net/~dannf/+archive/ubuntu/test , which should
complete building in about an hour or so. Would you mind trying it out
in your setup when complete?

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https://bugs.launchpad.net/bugs/1948598

Title:
  Can't unlock multiple devices in initramfs

Status in clevis package in Ubuntu:
  Fix Committed
Status in clevis source package in Focal:
  New
Status in clevis source package in Hirsute:
  New
Status in clevis source package in Impish:
  New
Status in clevis source package in Jammy:
  Fix Committed

Bug description:
  [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 finding the PID of the process that send up the interactive prompt "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 the saved PID-variable, so when the PID of the first process has been found it won't find any more processes of this type. This means it can only unlock the first 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 (https://github.com/latchset/clevis, version 17, commit 0abdfbc7812c8ef588ee22fd35941b5e831fdce7 on Feb 24, 2021)

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