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I have 3 partitions: EFI (/boot/efi), boot (/boot) and root (/). I want to encrypt just /. I can do this manually via the installer, but I want to preseed it.

How do I define it? My (non-encrypted) recipe looks something like the below. It is something of a mishmash of suggestions for EFI System Partitions I have found (found no clear guide).

boot-root ::
  100 100 100 fat32
    $primary
    $iflabel{ gpt }
    $reusemethod( }
    use_filesystem{ } filesystem{ vfat }
    method{ efi } format{ }
    mountpoint{ /boot/efi }
  .
  300 300 300 ext4
    use_filesystem{ } filesystem{ ext4 }
    method{ format } format{ }
    mountpoint{ /boot }
  .
  100% 3000 100% ext4
    use_filesystem{ } filesystem{ ext4 }
    method{ format } format{ }
    mountpoint{ / }
  .

How do I make sda3 be a physical partition for LUKS-encryption and then have a filesystem on top of that?

UPDATE:

I discovered that I can set the partition to be crypto as below, but there are still 3 issues:

  1. I still need to create and activate the encrypted volumes on the chosen partition
  2. I still need to set the correct ext4 filesystem on the encrypted volume after created and activated
  3. The recipe doesn't select the encryption type to dm-crypt which is required for creating and activating the encrypted volumes.

Still struggling mightily

boot-root ::
  100 100 100 fat32
    $primary
    $iflabel{ gpt }
    $reusemethod( }
    use_filesystem{ } filesystem{ vfat }
    method{ efi } format{ }
    mountpoint{ /boot/efi }
  .
  300 300 300 ext4
    use_filesystem{ } filesystem{ ext4 }
    method{ format } format{ }
    mountpoint{ /boot }
  .
  100% 3000 100% ext4
    method{ crypto } format{ }
  .
5
  • FYI, the labels like sda, sdb, sdc, etc don't always keep the same letters (a,b,c) between boots (mine switch every boot)
    – Xen2050
    May 4, 2016 at 14:53
  • 2
    @Xen2050 right you are, UUID or PARTUUID or LABEL or PARTLABEL are much better. In my case, I am booting up an image to format, so there is only one drive in. Either way, how do I set it up to crypt single partition? I can do it interactively, but I need it preseeded.
    – deitch
    May 4, 2016 at 16:00
  • Hmm, might be getting somewhere, but more questions. Will post other q.
    – deitch
    May 5, 2016 at 15:09
  • @deitch - is this a server partition configuration or a client or just a desktop partition example ? These 3 partitions are too few for your intention - there is missing /swap and /home - so you have to set up somehow an extended part of the harddisk with logical partitions - normally partitions allow only 4 on the whole but extended with logical partitions allow 4 times 63 partitions at maximum (and GPT allows much more) ?! - unix.stackexchange.com/questions/33555/… - regarding master and slaves partitions. May 12, 2016 at 2:11
  • @dschinn1001 actually its a template for a secure server. The core operating system is on a removable drive. The user data and swap are on an internal drive, which a systemd service finds and mounts appropriately. But ignoring that.... how can I set up the root to be encrypted without LVM?
    – deitch
    May 12, 2016 at 10:50

1 Answer 1

1

At first, open a root terminal:

sudo -i

Then fill the partition, which should be encrypted, with random data using a command like this:

openssl enc -aes-256-ctr -pass pass:"$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt < /dev/zero > /dev/sdxy

You have to replace sdxy with the partition which will be encrypted. Then type

cryptsetup luksFormat --cipher twofish-xts-plain64 --key-size 512 --hash sha512 --iter-time 2000 /dev/sdxy

to encrypt the partition sdxy. Open the volume and name it root:

cryptsetup luksOpen /dev/sdxy root

Use this command to make an ext4 filesystem inside it:

mkfs.ext4 /dev/mapper/root

Next you can start the installer. Chose "Something else" when being asked what you would like to do. Then chose the mount points for all your not-encrypted partitions. For your root partition, select /dev/mapper/root, click "Change". Then select ext4 for the filesystem type and set the mount point to /. Then click "Install now" and install Ubuntu normally.

When finished installing click "Continue testing". Open a terminal and type:

sudo -i
cd /mnt
mkdir root
mount /dev/mapper/root root
mount /dev/sdyz root/boot

sdyz should be replaced with your boot partition. Next, type:

chroot root
mount -t proc proc /proc
mount -t sysfs sys /sys
nano /etc/crypttab

Open a second terminal and type sudo blkid. Find the UUID for root (the one that says crypto_luks in the end) and paste it into /etc/crypttab. Then the file /etc/crypttab should look something like this:

root UUID=d68911dd-172a-4608-86d4-084eb72f409c none luks

Close the file with Ctrl+x, y and Enter. Type nano /etc/fstab in the terminal and check if everything looks right (e.g. the UUIDs).

At last, quit the chroot environment and type:

cryptsetup luksHeaderBackup /dev/sdxy --header-backup-file /root/root.img

This puts an image of the header of the encrypted partition into the folder /root and names it root.img. Then move the image to an external drive (in case of forgetting the password). Now you can reboot into your newly installed Ubuntu.

Source: http://thesimplecomputer.info/full-disk-encryption-with-ubuntu

4
  • Welcome to Ask Ubuntu! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. Aug 13, 2016 at 13:24
  • @Earl you are suggesting building the partition beforehand in a chroot (or containerized) environment, and then sticking it into the installer?
    – deitch
    Aug 14, 2016 at 1:02
  • How would I work that with the preseeder?
    – deitch
    Aug 14, 2016 at 1:02
  • I don't know, but that's at least a solution to make a LUKS-encrypted root-partition without LVM.
    – Earl Nick
    Aug 14, 2016 at 7:49

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