Would This Fedora Method of Encrypting /boot Work With Ubuntu 16.10?

Question

I found a tutorial for moving the /boot partition to / so that it falls under the LUKS encryption I already have in place. The tutorial was however made with Fedora in mind. Is this safe and will it work on Ubuntu 16.10?

[root@localhost ~]# mount --bind / /mnt/
[root@localhost ~]# cp -a /boot/* /mnt/boot/
[root@localhost ~]# cp -a /boot/.vmlinuz-* /mnt/boot/
[root@localhost ~]# diff -ur /boot/ /mnt/boot/
[root@localhost ~]# umount /mnt
[root@localhost ~]# umount /boot
[root@localhost ~]# sed -i -e '//boot/d' /etc/fstab
[root@localhost ~]# cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.backup
[root@localhost ~]# grub2-mkconfig > /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.0.4-301.fc22.x86_64
Found initrd image: /boot/initramfs-4.0.4-301.fc22.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-3f9d22f02d854d9a857066570127584a
Found initrd image: /boot/initramfs-0-rescue-3f9d22f02d854d9a857066570127584a.img
done
[root@localhost ~]# cat /boot/grub2/grub.cfg | grep cryptodisk
        insmod cryptodisk
        insmod cryptodisk
[root@localhost ~]# echo GRUB_ENABLE_CRYPTODISK=y >> /etc/default/grub
[root@localhost ~]# cat /etc/default/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="rd.lvm.lv=fedora/swap rd.lvm.lv=fedora/root rd.luks.uuid=luks-cb85c654-7561-48a3-9806-f8bbceaf3973 rhgb quiet"
GRUB_DISABLE_RECOVERY="true"
GRUB_ENABLE_CRYPTODISK=y
[root@localhost ~]# grub2-install /dev/sda
Installing for i386-pc platform.
Installation finished. No error reported.
[root@localhost ~]# reboot

The only annoying thing about this is that you have to type your LUKS password twice on boot but it's better than nothing. I did see a method that gets rid of the need to do that on boot but it seemed rather complicated and I don't feel like spending hours troubleshooting not being able to boot my system.

Answer 1

I can confirm that it works with Ubuntu 16.04.

The script does need to be adjusted a bit, though. Here's what I used:

$ sudo mkdir /mnt/root-bind && sudo mount --bind / /mnt/root-bind
$ sudo cp --archive --no-target-directory /boot /mnt/root-bind/boot
$ sudo diff -ur /boot /mnt/root-bind/boot  # Check output of this to verify that no differences are found.
$ sudo umount /mnt/root-bind && sudo rmdir /mnt/root-bind
$ sudo umount /boot
$ sudo cp -a /etc/fstab /etc/fstab.backup-before-removing-boot && sudo sed -i -e '/\/boot/d' /etc/fstab
$ echo 'insmod cryptodisk' | sudo tee --append /etc/grub.d/40_custom
$ echo 'GRUB_ENABLE_CRYPTODISK=y' | sudo tee --append /etc/default/grub
$ sudo update-grub
$ sudo grub-install /dev/sda  # Or whatever your main drive is.

That's what I just used, and it will (shortly [1]) be documented in more detail on this page of mine: Karl's IT Docs: Eddings Setup.

[1] Just as soon as I copy that site over to my rebuilt server, that is.