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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
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Adding upstream version 255.4.upstream/255.4
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="systemd-pcrphase.service" conditional='ENABLE_BOOTLOADER'
+ xmlns:xi="http://www.w3.org/2001/XInclude">
+
+ <refentryinfo>
+ <title>systemd-pcrphase.service</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-pcrphase.service</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-pcrphase.service</refname>
+ <refname>systemd-pcrphase-sysinit.service</refname>
+ <refname>systemd-pcrphase-initrd.service</refname>
+ <refname>systemd-pcrmachine.service</refname>
+ <refname>systemd-pcrfs-root.service</refname>
+ <refname>systemd-pcrfs@.service</refname>
+ <refname>systemd-pcrextend</refname>
+ <refpurpose>Measure boot phase into TPM2 PCR 11, machine ID and file system identity into PCR 15</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>systemd-pcrphase.service</filename></para>
+ <para><filename>systemd-pcrphase-sysinit.service</filename></para>
+ <para><filename>systemd-pcrphase-initrd.service</filename></para>
+ <para><filename>systemd-pcrmachine.service</filename></para>
+ <para><filename>systemd-pcrfs-root.service</filename></para>
+ <para><filename>systemd-pcrfs@.service</filename></para>
+ <para><filename>/usr/lib/systemd/systemd-pcrextend</filename> <optional><replaceable>STRING</replaceable></optional></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-pcrphase.service</filename>,
+ <filename>systemd-pcrphase-sysinit.service</filename>, and
+ <filename>systemd-pcrphase-initrd.service</filename> are system services that measure specific strings
+ into TPM2 PCR 11 during boot at various milestones of the boot process.</para>
+
+ <para><filename>systemd-pcrmachine.service</filename> is a system service that measures the machine ID
+ (see <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) into
+ PCR 15.</para>
+
+ <para><filename>systemd-pcrfs-root.service</filename> and <filename>systemd-pcrfs@.service</filename> are
+ services that measure file system identity information (i.e. mount point, file system type, label and
+ UUID, partition label and UUID) into PCR 15. <filename>systemd-pcrfs-root.service</filename> does so for
+ the root file system, <filename>systemd-pcrfs@.service</filename> is a template unit that measures the
+ file system indicated by its instance identifier instead.</para>
+
+ <para>These services require
+ <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> to be
+ used in a unified kernel image (UKI). They execute no operation when the stub has not been used to invoke
+ the kernel. The stub will measure the invoked kernel and associated vendor resources into PCR 11 before
+ handing control to it; once userspace is invoked these services then will extend TPM2 PCR 11 with certain
+ literal strings indicating phases of the boot process. During a regular boot process PCR 11 is extended
+ with the following strings:</para>
+
+ <orderedlist>
+ <listitem><para><literal>enter-initrd</literal> — early when the initrd initializes, before activating
+ system extension images for the initrd. It acts as a barrier between the time where the kernel
+ initializes and where the initrd starts operating and enables system extension images, i.e. code
+ shipped outside of the UKI. (This extension happens when the
+ <citerefentry><refentrytitle>systemd-pcrphase-initrd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ service is started.)</para></listitem>
+
+ <listitem><para><literal>leave-initrd</literal> — when the initrd is about to transition into the host
+ file system. It acts as barrier between initrd code and host OS code. (This extension happens when the
+ <filename>systemd-pcrphase-initrd.service</filename> service is stopped.)</para></listitem>
+
+ <listitem><para><literal>sysinit</literal> — when basic system initialization is complete (which
+ includes local file systems having been mounted), and the system begins starting regular system
+ services. (This extension happens when the
+ <citerefentry><refentrytitle>systemd-pcrphase-sysinit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ service is started.)</para></listitem>
+
+ <listitem><para><literal>ready</literal> — during later boot-up, after remote file systems have been
+ activated (i.e. after <filename>remote-fs.target</filename>), but before users are permitted to log in
+ (i.e. before <filename>systemd-user-sessions.service</filename>). It acts as barrier between the time
+ where unprivileged regular users are still prohibited to log in and where they are allowed to log in.
+ (This extension happens when the <filename>systemd-pcrphase.service</filename> service is started.)
+ </para></listitem>
+
+ <listitem><para><literal>shutdown</literal> — when the system shutdown begins. It acts as barrier
+ between the time the system is fully up and running and where it is about to shut down. (This extension
+ happens when the <filename>systemd-pcrphase.service</filename> service is stopped.)</para></listitem>
+
+ <listitem><para><literal>final</literal> — at the end of system shutdown. It acts as barrier between
+ the time the service manager still runs and when it transitions into the final shutdown phase where
+ service management is not available anymore. (This extension happens when the
+ <citerefentry><refentrytitle>systemd-pcrphase-sysinit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ service is stopped.)</para></listitem>
+ </orderedlist>
+
+ <para>During a regular system lifecycle, PCR 11 is extended with the strings
+ <literal>enter-initrd</literal>, <literal>leave-initrd</literal>, <literal>sysinit</literal>,
+ <literal>ready</literal>, <literal>shutdown</literal>, and <literal>final</literal>.</para>
+
+ <para>Specific phases of the boot process may be referenced via the series of strings measured, separated
+ by colons (the "phase path"). For example, the phase path for the regular system runtime is
+ <literal>enter-initrd:leave-initrd:sysinit:ready</literal>, while the one for the initrd is just
+ <literal>enter-initrd</literal>. The phase path for the boot phase before the initrd is an empty string;
+ because that's hard to pass around a single colon (<literal>:</literal>) may be used instead. Note that
+ the aforementioned six strings are just the default strings and individual systems might measure other
+ strings at other times, and thus implement different and more fine-grained boot phases to bind policy
+ to.</para>
+
+ <para>By binding policy of TPM2 objects to a specific phase path it is possible to restrict access to
+ them to specific phases of the boot process, for example making it impossible to access the root file
+ system's encryption key after the system transitioned from the initrd into the host root file system.
+ </para>
+
+ <para>Use
+ <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry> to
+ pre-calculate expected PCR 11 values for specific boot phases (via the <option>--phase=</option> switch).
+ </para>
+
+ <para><filename>systemd-pcrfs-root.service</filename> and <filename>systemd-pcrfs@.service</filename> are
+ automatically pulled into the initial transaction by
+ <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ for the root and <filename>/var/</filename> file
+ systems. <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ will do this for all mounts with the <option>x-systemd.pcrfs</option> mount option in
+ <filename>/etc/fstab</filename>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>The <filename>/usr/lib/systemd/system-pcrextend</filename> executable may also be invoked from the
+ command line, where it expects the word to extend into PCR 11, as well as the following switches:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>--bank=</option></term>
+
+ <listitem><para>Takes the PCR banks to extend the specified word into. If not specified the tool
+ automatically determines all enabled PCR banks and measures the word into all of
+ them.</para>
+
+ <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--pcr=</option></term>
+
+ <listitem><para>Takes the index of the PCR to extend. If <option>--machine-id</option> or
+ <option>--file-system=</option> are specified defaults to 15, otherwise defaults to 11.</para>
+
+ <xi:include href="version-info.xml" xpointer="v255"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--tpm2-device=</option><replaceable>PATH</replaceable></term>
+
+ <listitem><para>Controls which TPM2 device to use. Expects a device node path referring to the TPM2
+ chip (e.g. <filename>/dev/tpmrm0</filename>). Alternatively the special value <literal>auto</literal>
+ may be specified, in order to automatically determine the device node of a suitable TPM2 device (of
+ which there must be exactly one). The special value <literal>list</literal> may be used to enumerate
+ all suitable TPM2 devices currently discovered.</para>
+
+ <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--graceful</option></term>
+
+ <listitem><para>If no TPM2 firmware, kernel subsystem, kernel driver or device support is found, exit
+ with exit status 0 (i.e. indicate success). If this is not specified any attempt to measure without a
+ TPM2 device will cause the invocation to fail.</para>
+
+ <xi:include href="version-info.xml" xpointer="v253"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--machine-id</option></term>
+
+ <listitem><para>Instead of measuring a word specified on the command line into PCR 11, measure the
+ host's machine ID into PCR 15.</para>
+
+ <xi:include href="version-info.xml" xpointer="v253"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--file-system=</option></term>
+
+ <listitem><para>Instead of measuring a word specified on the command line into PCR 11, measure
+ identity information of the specified file system into PCR 15. The parameter must be the path to the
+ established mount point of the file system to measure.</para>
+
+ <xi:include href="version-info.xml" xpointer="v253"/></listitem>
+ </varlistentry>
+
+ <xi:include href="standard-options.xml" xpointer="help" />
+ <xi:include href="standard-options.xml" xpointer="version" />
+
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Files</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>/run/log/systemd/tpm2-measure.log</filename></term>
+
+ <listitem><para>Measurements are logged into an event log file maintained in
+ <filename>/run/log/systemd/tpm2-measure.log</filename>, which contains a <ulink
+ url="https://www.rfc-editor.org/rfc/rfc7464.html">JSON-SEQ</ulink> series of objects that follow the
+ general structure of the <ulink
+ url="https://trustedcomputinggroup.org/resource/canonical-event-log-format/">TCG Common Event Log
+ Format (CEL-JSON)</ulink> event objects (but lack the <literal>recnum</literal>
+ field).</para>
+
+ <para>A <constant>LOCK_EX</constant> BSD file lock (<citerefentry
+ project='man-pages'><refentrytitle>flock</refentrytitle><manvolnum>2</manvolnum></citerefentry>) on
+ the log file is acquired while the measurement is made and the file is updated. Thus, applications
+ that intend to acquire a consistent quote from the TPM with the associated snapshot of the event log
+ should acquire a <constant>LOCK_SH</constant> lock while doing so.</para>
+
+ <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <ulink url="https://systemd.io/TPM2_PCR_MEASUREMENTS">TPM2 PCR Measurements Made by systemd</ulink>
+ </para>
+ </refsect1>
+
+</refentry>