Disk Encryption

This guide provides an example setup for a single-disk ZFS system with native encryption, accessible for decryption remotely.

Warning

This configuration only applies to systemd-boot enabled systems and requires UEFI booting.

Replace the highlighted lines with your own disk-id. You can find our your disk-id by executing:

lsblk --output NAME,ID-LINK,FSTYPE,SIZE,MOUNTPOINT

Single DiskRaid 1

Below is the configuration for disko.nix

name="__codelineno-1-1" href="#__codelineno-1-1"> { lib, config, clan-core, ... }: let suffix = config.clan.core.vars.generators.disk-id.files.diskId.value; mirrorBoot = idx: { # suffix is to prevent disk name collisions name = idx + suffix; type = "disk"; device = "/dev/disk/by-id/${idx}"; content = { type = "gpt"; partitions = { class="hll"> "boot" = { size = "1M"; type = "EF02"; # for grub MBR priority = 1; }; "ESP" = lib.mkIf (idx == "nvme-eui.002538b931b59865") { size = "1G"; type = "EF00"; content = { type = "filesystem"; format = "vfat"; mountpoint = "/boot"; mountOptions = [ "nofail" ]; }; }; "root" = { size = "100%"; content = { type = "zfs"; pool = "zroot"; }; }; }; }; }; in { imports = [ clan-core.clanModules.disk-id ]; class="hll"> config = { boot.loader.systemd-boot.enable = true; disko.devices = { disk = { x = mirrorBoot "nvme-eui.002538b931b59865"; }; zpool = { zroot = { type = "zpool"; rootFsOptions = { compression = "lz4"; acltype = "posixacl"; xattr = "sa"; "com.sun:auto-snapshot" = "true"; mountpoint = "none"; }; datasets = { "root" = { type = "zfs_fs"; options = { mountpoint = "none"; encryption = "aes-256-gcm"; keyformat = "passphrase"; keylocation = "file:///tmp/secret.key"; }; }; "root/nixos" = { type = "zfs_fs"; options.mountpoint = "/"; mountpoint = "/"; }; "root/home" = { type = "zfs_fs"; options.mountpoint = "/home"; mountpoint = "/home"; }; "root/tmp" = { type = "zfs_fs"; mountpoint = "/tmp"; options = { mountpoint = "/tmp"; sync = "disabled"; }; }; }; }; }; }; }; }

Below is the configuration for disko.nix

  {
    lib,
    config,
    clan-core,
    ...
  }:
  let
    suffix = config.clan.core.vars.generators.disk-id.files.diskId.value;
    mirrorBoot = idx: {
      # suffix is to prevent disk name collisions
      name = idx + suffix;
      type = "disk";
      device = "/dev/disk/by-id/${idx}";
      content = {
        type = "gpt";
        partitions = {
          "boot" = {
            size = "1M";
            type = "EF02"; # for grub MBR
            priority = 1;
          };
          "ESP" = lib.mkIf (idx == "nvme-eui.002538b931b59865") {
            size = "1G";
            type = "EF00";
            content = {
              type = "filesystem";
              format = "vfat";
              mountpoint = "/boot";
              mountOptions = [ "nofail" ];
            };
          };
          "root" = {
            size = "100%";
            content = {
              type = "zfs";
              pool = "zroot";
            };
          };
        };
      };
    };
  in
  {
    imports = [
      clan-core.clanModules.disk-id
    ];

    config = {
      boot.loader.systemd-boot.enable = true;

      disko.devices = {
        disk = {
          x = mirrorBoot "nvme-eui.002538b931b59865";
          y = mirrorBoot "my-other-disk";
        };
        zpool = {
          zroot = {
            type = "zpool";
            rootFsOptions = {
              compression = "lz4";
              acltype = "posixacl";
              xattr = "sa";
              "com.sun:auto-snapshot" = "true";
              mountpoint = "none";
            };
            datasets = {
              "root" = {
                type = "zfs_fs";
                options = {
                  mountpoint = "none";
                  encryption = "aes-256-gcm";
                  keyformat = "passphrase";
                  keylocation = "file:///tmp/secret.key";
                };
              };
              "root/nixos" = {
                type = "zfs_fs";
                options.mountpoint = "/";
                mountpoint = "/";
              };
              "root/home" = {
                type = "zfs_fs";
                options.mountpoint = "/home";
                mountpoint = "/home";
              };
              "root/tmp" = {
                type = "zfs_fs";
                mountpoint = "/tmp";
                options = {
                  mountpoint = "/tmp";
                  sync = "disabled";
                };
              };
            };
          };
        };
      };
    };
  }

Below is the configuration for initrd.nix. Replace <yourkey> with your ssh public key. Replace kernelModules with the ethernet module loaded one on your target machine.

{config, pkgs, ...}:

{

  boot.initrd.systemd = {
    enable = true;
  };

  # uncomment this if you want to be asked for the decryption password on login
  #users.root.shell = "/bin/systemd-tty-ask-password-agent";

  boot.initrd.network = {
    enable = true;

    ssh = {
      enable = true;
      port = 7172;
      authorizedKeys = [ "<yourkey>" ];
      hostKeys = [
        "/var/lib/initrd-ssh-key"
      ];
    };
  };
  boot.initrd.availableKernelModules = [
    "xhci_pci"
  ];

  # Find out the required network card driver by running `lspci -k` on the target machine
  boot.initrd.kernelModules = [ "r8169" ];
}

Step 1: Copying SSH Public Key

Before starting the installation process, ensure that the SSH public key is copied to the NixOS installer.

Copy your public SSH key to the installer, if it has not been copied already:

ssh-copy-id -o PreferredAuthentications=password -o PubkeyAuthentication=no root@nixos-installer.local

Step 1.5: Prepare Secret Key and Clear Disk Data

Access the installer using SSH:

ssh root@nixos-installer.local

Create a secret.key file in /tmp using nano or another text editor:

nano /tmp/secret.key

Discard the old disk partition data:

blkdiscard /dev/disk/by-id/nvme-eui.002538b931b59865

Run the clan machine installation with the following command:

clan machines install gchq-local --target-host root@nixos-installer --yes --no-reboot

Step 2: ZFS Pool Import and System Installation

SSH into the installer once again:

ssh root@nixos-installer.local

Perform the following commands on the remote installation environment:

zpool import zroot
zfs set keylocation=prompt zroot/root
zfs load-key zroot/root
zfs set mountpoint=/mnt zroot/root/nixos
mount /dev/nvme0n1p2 /mnt/boot

Disconnect from the SSH session:

CTRL+D

Securely copy your local initrd_rsa_key to the installer's /mnt directory:

scp ~/.ssh/initrd_rsa_key root@nixos-installer.local:/mnt/var/lib/initrd-ssh-key

SSH back into the installer:

ssh root@nixos-installer.local

Navigate to the /mnt directory, enter the nixos-enter environment, and then exit:

cd /mnt
nixos-enter
realpath /run/current-system
exit

Run the nixos-install command with the appropriate system path <SYS_PATH>:

nixos-install --no-root-passwd --no-channel-copy --root /mnt --system <SYS_PATH>

After the installation process, unmount /mnt/boot, change the ZFS mountpoint, and reboot the system:

umount /mnt/boot
cd /
zfs set mountpoint=/ zroot/root/nixos
reboot

Perform a hard reboot of the machine and remove the USB stick.

Step 3: Accessing the Initial Ramdisk (initrd) Environment

SSH into the initrd environment using the initrd_rsa_key and provided port:

ssh -p 7172 root@192.168.178.141

Run the systemd-tty-ask-password-agent utility to query a password:

systemd-tty-ask-password-agent --query

After completing these steps, your NixOS should be successfully installed and ready for use.

Note: Replace root@nixos-installer.local and 192.168.178.141 with the appropriate user and IP addresses for your setup. Also, adjust <SYS_PATH> to reflect the correct system path for your environment.