auto-enroll: use safe auto enrollment rather than YOLO enrollment

nix/modules/lanzaboote.nix

@@ -3,10 +3,6 @@ with lib;
 let
   cfg = config.boot.lanzaboote;
 
-  sbctlWithPki = pkgs.sbctl.override {
-    databasePath = "/tmp/pki";
-  };
-
   loaderSettingsFormat = pkgs.formats.keyValue {
     mkKeyValue = k: v: if v == null then "" else
     lib.generators.mkKeyValueDefault { } " " k v;
@@ -15,12 +11,46 @@ let
   loaderConfigFile = loaderSettingsFormat.generate "loader.conf" cfg.settings;
 
   configurationLimit = if cfg.configurationLimit == null then 0 else cfg.configurationLimit;
+
+  loaderKeyOpts = { ... }:
+    let
+      mkAuthOption = variableName: mkOption {
+        type = types.nullOr types.path;
+        default = null;
+        description = "Auth variable file for ${variableName}";
+      };
+    in
+    {
+      options = {
+        db = mkAuthOption "db";
+        KEK = mkAuthOption "KEK";
+        PK = mkAuthOption "PK";
+      };
+    };
 in
 {
   options.boot.lanzaboote = {
     enable = mkEnableOption "Enable the LANZABOOTE";
 
-    enrollKeys = mkEnableOption "Automatic enrollment of the keys using sbctl";
+    safeAutoEnroll = mkOption {
+      type = types.nullOr (types.submodule loaderKeyOpts);
+      default = null;
+      description = ''
+        Perform safe automatic (or manual) enrollment of Secure Boot variables
+        via .auth variables.
+
+        Files will be put in /loader/keys/auto/{db,KEK,PK}.auth.
+
+        If you are using systemd-boot, they will be enrolled if it's deemed
+        safe or
+        [`secure-boot-enroll`](https://www.freedesktop.org/software/systemd/man/latest/loader.conf.html#secure-boot-enroll)
+        is set to `force`.
+
+        Usually, detected virtual machine environments are deemed safe.
+
+        Not all bootloaders support safe automatic enrollment.
+      '';
+    };
 
     configurationLimit = mkOption {
       default = config.boot.loader.systemd-boot.configurationLimit;
@@ -109,25 +139,31 @@ in
     boot.loader.supportsInitrdSecrets = true;
     boot.loader.external = {
       enable = true;
-      installHook = pkgs.writeShellScript "bootinstall" ''
-        ${optionalString cfg.enrollKeys ''
-          mkdir -p /tmp/pki
-          cp -r ${cfg.pkiBundle}/* /tmp/pki
-          ${sbctlWithPki}/bin/sbctl enroll-keys --yes-this-might-brick-my-machine
-        ''}
-
-        # Use the system from the kernel's hostPlatform because this should
-        # always, even in the cross compilation case, be the right system.
-        ${cfg.package}/bin/lzbt install \
-          --system ${config.boot.kernelPackages.stdenv.hostPlatform.system} \
-          --systemd ${config.systemd.package} \
-          --systemd-boot-loader-config ${loaderConfigFile} \
-          --public-key ${cfg.publicKeyFile} \
-          --private-key ${cfg.privateKeyFile} \
-          --configuration-limit ${toString configurationLimit} \
-          ${config.boot.loader.efi.efiSysMountPoint} \
-          /nix/var/nix/profiles/system-*-link
-      '';
+      installHook =
+        let
+          copyAutoEnrollIfNeeded = varName: optionalString (cfg.safeAutoEnroll.${varName} != null) ''cp -a ${cfg.safeAutoEnroll.${varName}} "$ESP/loader/keys/auto/${varName}.auth"'';
+        in
+        pkgs.writeShellScript "bootinstall" ''
+          export ESP="${config.boot.loader.efi.efiSysMountPoint}"
+          ${optionalString (cfg.safeAutoEnroll != null) ''
+            mkdir -p "$ESP/loader/keys/auto"
+            ${copyAutoEnrollIfNeeded "PK"}
+            ${copyAutoEnrollIfNeeded "KEK"}
+            ${copyAutoEnrollIfNeeded "db"}
+          ''}
+
+          # Use the system from the kernel's hostPlatform because this should
+          # always, even in the cross compilation case, be the right system.
+          ${cfg.package}/bin/lzbt install \
+            --system ${config.boot.kernelPackages.stdenv.hostPlatform.system} \
+            --systemd ${config.systemd.package} \
+            --systemd-boot-loader-config ${loaderConfigFile} \
+            --public-key ${cfg.publicKeyFile} \
+            --private-key ${cfg.privateKeyFile} \
+            --configuration-limit ${toString configurationLimit} \
+            "$ESP" \
+            /nix/var/nix/profiles/system-*-link
+        '';
     };
 
     systemd.services.fwupd = lib.mkIf config.services.fwupd.enable {

nix/tests/lanzaboote.nix

@@ -3,7 +3,7 @@
 }:
 
 let
-  inherit (pkgs) lib system;
+  inherit (pkgs) lib system runCommand;
   defaultTimeout = 5 * 60; # = 5 minutes
 
   inherit (pkgs.stdenv.hostPlatform) efiArch;
@@ -88,6 +88,21 @@ let
       testScript = ''
         ${lib.optionalString useTPM2 tpm2Initialization}
         ${lib.optionalString readEfiVariables efiVariablesHelpers}
+
+        def is_guest_induced_reset(event):
+            return event['event'] == 'SHUTDOWN' and event.get('data', {}).get('reason') == 'guest-reset'
+
+        machine.start()
+        if machine.qmp_client is None:
+          import sys; sys.exit(1)
+
+        # We expect a shutdown for guest-reset reasons.
+        print('Waiting for a guest-reset...')
+        machine.wait_for_qmp_event(is_guest_induced_reset)
+        print('Shutdown detected.')
+
+        machine.booted = False
+        machine.start()
         ${testScript}
       '';
 
@@ -147,7 +162,32 @@ let
         };
         boot.lanzaboote = {
           enable = true;
-          enrollKeys = lib.mkDefault true;
+          # Under aarch64, various things goes wrong...
+          settings.secure-boot-enroll = lib.mkIf pkgs.hostPlatform.isAarch64 "force";
+          safeAutoEnroll =
+            let
+              signVariable = varName:
+                let
+                  GUID = ./fixtures/uefi-keys/GUID;
+                  publicKey = ./fixtures/uefi-keys/keys/${varName}/${varName}.pem;
+                  privateKey = ./fixtures/uefi-keys/keys/${varName}/${varName}.key;
+                in
+                runCommand "sign-${varName}-via-snakeoil-pki"
+                  {
+                    nativeBuildInputs = [ pkgs.efitools ];
+                  } ''
+                  cert-to-efi-sig-list -g ${GUID} ${publicKey} ${varName}.esl
+                  sign-efi-sig-list -t "$(date --date '@1' '+%Y-%m-%d %H:%M:%S')" \
+                    -k ${privateKey} -c ${publicKey} ${varName} ${varName}.esl ${varName}.auth
+
+                  mv ${varName}.auth $out
+                '';
+            in
+            {
+              db = signVariable "db";
+              KEK = signVariable "KEK";
+              PK = signVariable "PK";
+            };
           pkiBundle = ./fixtures/uefi-keys;
         };
       };
@@ -200,7 +240,6 @@ in
   basic = mkSecureBootTest {
     name = "lanzaboote";
     testScript = ''
-      machine.start()
       assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
     '';
   };
@@ -211,7 +250,6 @@ in
       boot.initrd.systemd.enable = true;
     };
     testScript = ''
-      machine.start()
       assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
     '';
   };
@@ -234,7 +272,6 @@ in
         '';
       };
       testScript = ''
-        machine.start()
         machine.wait_for_unit("multi-user.target")
 
         machine.succeed("cmp ${secret} /secret-from-initramfs")
@@ -276,7 +313,6 @@ in
         };
       };
       testScript = ''
-        machine.start()
         machine.wait_for_unit("multi-user.target")
 
         # Assert that only three boot files exists (a single kernel and a two
@@ -326,7 +362,6 @@ in
       };
     };
     testScript = ''
-      machine.start()
       print(machine.succeed("ls -lah /boot/EFI/Linux"))
       # TODO: make it more reliable to find this filename, i.e. read it from somewhere?
       machine.succeed("bootctl set-default nixos-generation-1-specialisation-variant-\*.efi")
@@ -359,7 +394,6 @@ in
           boot.bootspec.enable = lib.mkForce false;
         };
         testScript = ''
-          machine.start()
           assert "Secure Boot: enabled (user)" in machine.succeed("bootctl status")
         '';
       };
@@ -371,8 +405,6 @@ in
       boot.loader.systemd-boot.consoleMode = "auto";
     };
     testScript = ''
-      machine.start()
-
       actual_loader_config = machine.succeed("cat /boot/loader/loader.conf").split("\n")
       expected_loader_config = ["timeout 0", "console-mode auto"]
 
@@ -393,8 +425,6 @@ in
       # Finally, we will reboot.
       # We will also assert that systemd-boot is not running
       # by checking for the sd-boot's specific EFI variables.
-      machine.start()
-
       # By construction, nixos-generation-1.efi is the stub we are interested in.
       # TODO: this should work -- machine.succeed("efibootmgr -d /dev/vda -c -l \\EFI\\Linux\\nixos-generation-1.efi") -- efivars are not persisted
       # across reboots atm?
@@ -447,8 +477,6 @@ in
     useTPM2 = true;
     readEfiVariables = true;
     testScript = ''
-      machine.start()
-
       # TODO: the other variables are not yet supported.
       expected_variables = [
         "StubPcrKernelImage"