Merge pull request 'feature(lanzaboote): add support for secure-boot through lanazaboote' (#88) from feature/secure_boot into main

Reviewed-on: #88

INSTALLATION.md

@@ -102,10 +102,62 @@ nixos-install
 
 ## how to deploy the initial config
 - Don't forget to install the bootloader, if you changed it since `nixos-install`
+- The fresh install has no flakes and no git yet, a temporary shell is enough
+- If the installer iso is older than the flake's nixpkgs, `--no-reexec` keeps
+  `nixos-rebuild` from re-executing a newer version of itself, which can fail
+  against the older systemd of the fresh install (only needed once)
+- Set a password for the user before rebooting, `users.nix` doesn't set one
 ```bash
-$ sudo nixos-rebuild --install-bootloader switch --flake .#host_name
+$ export NIX_CONFIG="experimental-features = nix-command flakes"
+$ nix-shell -p git
+$ sudo nixos-rebuild --install-bootloader boot --flake .#host_name --no-reexec
+$ sudo passwd aaron
 ```
 
+## how to enable secure boot
+Secure Boot uses lanzaboote with our own keys, see `modules/nixos/lanzaboote.nix`.
+Do this after the initial config is deployed and boots.
+
+1. create the keys, before the first rebuild with the lanzaboote module
+```bash
+# the keys end up in /var/lib/sbctl, they never leave the host
+$ sudo nix run nixpkgs#sbctl -- create-keys
+```
+
+2. import `modules/nixos/lanzaboote.nix` in the host's `configuration.nix`, rebuild and check the signatures
+```bash
+$ sudo nixos-rebuild switch --flake .#host_name
+# EFI/Linux/*.efi and the bootloader must be signed, kernels in EFI/nixos
+# are not, lanzaboote checks them by hash
+$ sudo sbctl verify
+```
+
+3. reboot once with Secure Boot still disabled, to make sure the new entries boot
+
+4. in the firmware (F2), erase all Secure Boot keys, then boot nixos again
+```bash
+# "Setup Mode: ✗ Enabled", the ✗ only means the state is insecure
+$ sudo sbctl status
+```
+
+5. enroll the keys
+```bash
+# only our own keys, no microsoft keys
+$ sudo sbctl enroll-keys
+```
+- sbctl refuses if the TPM eventlog shows option ROMs (e.g. a dedicated gpu).
+  Don't force it, either trust exactly those with `--tpm-eventlog` or
+  microsoft's keys with `--microsoft`. Without either, the firmware may not
+  start the device, in the worst case the machine doesn't boot at all.
+
+6. enable Secure Boot in the firmware and set a firmware password, then check
+```bash
+$ bootctl status | grep "Secure Boot"   # enabled (user)
+$ sudo sbctl status                     # Secure Boot: ✓ Enabled
+```
+- If it doesn't boot anymore, disabling Secure Boot in the firmware boots as before
+- Losing the keys isn't fatal: erase the keys in the firmware and start over at step 1
+
 ## how to upgrade the system
 ```bash
 $ cd /path/to/repo

flake.lock

@@ -1,5 +1,36 @@
 {
   "nodes": {
+    "crane": {
+      "locked": {
+        "lastModified": 1789760033,
+        "narHash": "sha256-jtT4yxZpR8seYnlCMMWSSPlFN92zO6ICuZ8pJrmi86k=",
+        "owner": "ipetkov",
+        "repo": "crane",
+        "rev": "73b980519cefc727a5f6cc8e5c0947a2f9be6edd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ipetkov",
+        "repo": "crane",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1767039857,
+        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
+        "owner": "NixOS",
+        "repo": "flake-compat",
+        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
     "flake-parts": {
       "inputs": {
         "nixpkgs-lib": [
@@ -41,6 +72,30 @@
         "type": "github"
       }
     },
+    "lanzaboote": {
+      "inputs": {
+        "crane": "crane",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "pre-commit": "pre-commit",
+        "rust-overlay": "rust-overlay"
+      },
+      "locked": {
+        "lastModified": 1790423250,
+        "narHash": "sha256-sr4Kfp6yaXUeyKL6n0Y8/ElcR3momIRC20HFc+LF22s=",
+        "owner": "nix-community",
+        "repo": "lanzaboote",
+        "rev": "c1c5edd31802d181c8aa2c71588995d93425d650",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "ref": "v1.2.0",
+        "repo": "lanzaboote",
+        "type": "github"
+      }
+    },
     "nixos-hardware": {
       "inputs": {
         "nixpkgs": [
@@ -119,15 +174,59 @@
         "type": "github"
       }
     },
+    "pre-commit": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "nixpkgs": [
+          "lanzaboote",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1789514889,
+        "narHash": "sha256-PFD1nxptCXJyJoiYO1gf/5Vv43yqGpHtMC6LUhl9/pQ=",
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "rev": "59f4ca0d063a1a3ec722c88b51a33004862e5379",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "git-hooks.nix",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "home-manager": "home-manager",
+        "lanzaboote": "lanzaboote",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs",
         "nixvim": "nixvim",
         "noctalia": "noctalia"
       }
     },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "lanzaboote",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1789889921,
+        "narHash": "sha256-aL/ogiN7qZCGeNovS1f9hX73jwYIKb4Pcq6AZm57WtY=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "1fb104a12a8667045559b2575d6d448ae2fbd99b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
     "systems": {
       "flake": false,
       "locked": {

flake.nix

@@ -11,6 +11,10 @@
       url = "github:noctalia-dev/noctalia-shell";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    lanzaboote = {
+      url = "github:nix-community/lanzaboote/v1.2.0";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     nixos-hardware = {
       url = "github:NixOS/nixos-hardware";
       inputs.nixpkgs.follows = "nixpkgs";

hosts/krypton/configuration.nix

@@ -12,6 +12,7 @@
     ../../modules/nixos/certificates.nix
     ../../modules/nixos/docker.nix
     ../../modules/nixos/gnupg.nix
+    ../../modules/nixos/lanzaboote.nix
     ../../modules/nixos/locales.nix
     ../../modules/nixos/networking.nix
     ../../modules/nixos/niri.nix

modules/nixos/lanzaboote.nix

@@ -0,0 +1,25 @@
+# Secure Boot with lanzaboote. systemd-boot stays the bootloader, but lanzaboote
+# installs it signed and writes signed boot entries instead of the nixos module.
+# The keys are created once per host with `sudo sbctl create-keys` before the
+# first rebuild, and enrolled into the firmware with `sbctl enroll-keys`.
+
+{
+  inputs,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  imports = [ inputs.lanzaboote.nixosModules.lanzaboote ];
+
+  boot.loader.systemd-boot.enable = lib.mkForce false;
+
+  boot.lanzaboote = {
+    enable = true;
+    pkiBundle = "/var/lib/sbctl";
+  };
+
+  # key management and verification
+  environment.systemPackages = [ pkgs.sbctl ];
+}