Mounting encrypted Linux partitions from a Live Disc

January 2, 2022

Summary

I’m running Manjaro and recently had some issues booting. I have encrypted partitions and haven’t ever had to figure out how to mount them manually from a Live Disc environment. This blog is a braindump of notes I used to get things working. I think I’m using dm-crypt directly, but could be wrong about that.

FIXME this probably needs editing/expanding /

Once chroot-ed in, you can read the most recent boot logs

journalctl -b

…and if that gives

-- No entries --

…then you can find the right boot with:

journalctl --list-boots
journalctl -b -1

Have to scroll back past shutdown stuff, but found

Jan 08 18:14:58 tom-x1eg2 lightdm[3003]: Traceback (most recent call last):
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:   File "/sbin/prime-offload", line 33, in <module>
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:     sys.exit(load_entry_point('optimus-manager==1.4', 'console_scripts', 'prime-offload')())
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:   File "/sbin/prime-offload", line 22, in importlib_load_entry_point
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:     for entry_point in distribution(dist_name).entry_points
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:   File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 919, in distribution
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:     return Distribution.from_name(distribution_name)
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:   File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 518, in from_name
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]:     raise PackageNotFoundError(name)
Jan 08 18:14:58 tom-x1eg2 lightdm[3003]: importlib.metadata.PackageNotFoundError: No package metadata was found for optimus-manager
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]: Traceback (most recent call last):
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:   File "/sbin/prime-switch", line 33, in <module>
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:     sys.exit(load_entry_point('optimus-manager==1.4', 'console_scripts', 'prime-switch')())
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:   File "/sbin/prime-switch", line 22, in importlib_load_entry_point
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:     for entry_point in distribution(dist_name).entry_points
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:   File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 919, in distribution
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:     return Distribution.from_name(distribution_name)
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:   File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 518, in from_name
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]:     raise PackageNotFoundError(name)
Jan 08 18:15:00 tom-x1eg2 lightdm[3005]: importlib.metadata.PackageNotFoundError: No package metadata was found for optimus-manager

Can verify with

optimus-manager --status

…which gets the same error.

The fix is to reinstall this package, which you could try with:

$ yay -S optimus-manager # WON'T WORK!!!
 -> error fetching optimus-manager: System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down 
	 context: exit status 1

…but that won’t work because it’s just a chroot. Instead, boot into a “no GUI” session and reinstall there. Then restart.

Mounting partitions

boot Manjaro live image
start terminal
launch a new terminal with a sane font size (thanks https://faq.i3wm.org/question/5725/any-ideas-how-to-change-the-font-size-for-a-urxvt-terminal-opened-on-a-specific-display-or-workspace.1.html)
```
urxvt -fn "xft:Bitstream Vera Sans Mono:pixelsize=22"
```
find the root partition. I don’t think I’m using LVM here because I don’t need more than 4 partitions:
```
sudo fdisk -l
```
unlock/open that encrypted partition. Note the last param is just a unqiue name, it can be anything
```
sudo cryptsetup open /dev/nvme1n1p2 theroot
```

mount the unlocked partition

sudo mkdir /mnt/root
sudo mount /dev/mapper/theroot /mnt/root

if you run two disks, and you want to mount that second one into the first, you do it like any other mount, after you’ve unlocked it (assuming it’s also encrypted)
```
sudo cryptsetup open /dev/nvme0n1p0 thesecond
sudo mount /dev/mapper/thesecond /mnt/root/<path>
```
at this point you can browse both partitions like normal, just cd you way around. If you want to chroot in, you’ll need to mount some other things: thanks (https://github.com/FadeMind/mhwd-chroot/blob/master/mhwd-chroot-shell)
```
for curr in /{proc,dev,sys,dev/pts,tmp}; do
  echo "mounting $curr"
  sudo mount -B $curr /mnt/root$curr
done
```
now we chroot in:
```
sudo chroot /mnt/root
```

make sure you’re in the chroot from above
vim /etc/default/grub
```
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=3
```
update grub
```
update-grub
```

Boot to text-only mode

Now you’ll actually see the grub menu when booting, you can use the e to edit the boot command trick
find the line with vmlinuz and add 3 to the end (go to the next line and press left to get to the end of that long line quickly)
boot with F10 thanks https://archived.forum.manjaro.org/t/boot-in-pure-text-mode/21047

Check boot logs

journalctl -b | less

Mounting encrypted Linux partitions from a Live Disc

Summary

Mounting partitions

Enabling grub menu

Boot to text-only mode

Check boot logs