Re: [dm-crypt] Troubleshooting: Header Conversion to argon2id

[Guilhem Moulin <guilhem@fripost.org>]

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On Thu, 13 Sep 2018 at 00:47:00 +0000, procmem wrote:
> Guilhem Moulin:
>> On Wed, 12 Sep 2018 at 15:21:00 +0000, procmem wrote:
>>> cryptsetup convert /dev/vda5 --type luks2 --debug
>>> […]
>>> Cannot convert device /dev/vda5 which is still in use.
>>> […]
>>> Command failed with code -5 (device already exists or device is busy).
>> 
>> As the error message indicates, you need to remove (ie, close) the
>> mapped device first.  If that device is required for your system to run
>> (for instance if it's holding the root file system) you won't be able to
>> run `cryptsetup luksClose $name` from the main system; however you
>> should be able to perform `cryptsetup convert` from a live CD, or from
>> the initramfs image.
> 
> initramfs sounds like the most versatile option. Any pointers on how to
> to this? Searching SE turns up irrelevant results.

Before rebooting you might want to make sure the ‘algif_skcipher’ kernel
module is included in the initramfs image, otherwise you might not be
able to open LUKS2 volumes.  (See https://bugs.debian.org/896968 for
details.)  To do so, run the following two commands:

    echo algif_skcipher | sudo tee -a /etc/initramfs-tools/modules
    sudo update-initramfs -u

Now assuming your bootloader is GRUB, reboot, press <E> to obtain an
emacs-like screen, append “ break=premount” to the line starting with
“initrd”, and press <Ctrl>+<X> to boot.  (The edit is transient and
won't survive the next reboot.)  You should land into an initramfs debug
shell; see initramfs-tools(7) for details.

That has probably become off-topic for the dm-crypt list, by the way
(discussing how to reboot into an initramfs shell has nothing to do with
dm-crypt, LUKS, or cryptsetup(8) per se); the user support channels of
your distro might be a better venue for this.

-- 
Guilhem.

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