pcrextend: automatically measure SMBIOS product ID at boot

Now that PCRs are not that expensive anymore, let's use them to measure
the SMBIOS product ID to one.

units/meson.build

@@ -556,6 +556,11 @@ units = [
           'conditions' : ['ENABLE_BOOTLOADER', 'HAVE_OPENSSL', 'HAVE_TPM2'],
           'symlinks' : ['factory-reset.target.wants/'],
         },
+        {
+          'file' : 'systemd-pcrproduct.service.in',
+          'conditions' : ['ENABLE_BOOTLOADER', 'HAVE_OPENSSL', 'HAVE_TPM2'],
+          'symlinks' : ['sysinit.target.wants/'],
+        },
         {
           'file' : 'systemd-pcrphase-initrd.service.in',
           'conditions' : ['ENABLE_BOOTLOADER', 'HAVE_OPENSSL', 'HAVE_TPM2', 'ENABLE_INITRD'],

units/systemd-pcrproduct.service.in

@@ -0,0 +1,23 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=TPM PCR Product ID Measurement
+Documentation=man:systemd-pcrproduct.service(8)
+DefaultDependencies=no
+Conflicts=shutdown.target
+After=tpm2.target
+Before=sysinit.target shutdown.target
+ConditionPathExists=!/etc/initrd-release
+ConditionSecurity=measured-uki
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart={{LIBEXECDIR}}/systemd-pcrextend --graceful --product-id