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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:35:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:35:18 +0000
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treea5df1a06754bdd014cb975c051c83b01c9a97532 /man/systemd-pcrphase.service.xml
parentInitial commit. (diff)
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Adding upstream version 252.22.upstream/252.22upstream
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='HAVE_GNU_EFI'
+ 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-pcrphase</refname>
+ <refpurpose>Measure boot phase into TPM2 PCR 11</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>/usr/lib/systemd/system-pcrphase</filename> <replaceable>STRING</replaceable></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>These services require
+ <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> to be
+ used in a unified kernel image (UKI) setup. They execute no operation when invoked 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
+ certain literal strings indicating various phases of the boot process into TPM2 PCR 11. During a regular
+ boot process the following strings are extended into PCR 11.</para>
+
+ <orderedlist>
+ <listitem><para><literal>enter-initrd</literal> is extended into PCR 11 early when the initrd
+ initializes, before activating system extension images for the initrd. It is supposed to act as 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 string is extended at start of
+ <filename>systemd-pcrphase-initrd.service</filename>.)</para></listitem>
+
+ <listitem><para><literal>leave-initrd</literal> is extended into PCR 11 when the initrd is about to
+ transition into the host file system, i.e. when it achieved its purpose. It is supposed to act as
+ barrier between kernel/initrd code and host OS code. (This string is extended at stop of
+ <filename>systemd-pcrphase-initrd.service</filename>.)</para></listitem>
+
+ <listitem><para><literal>sysinit</literal> is extended into PCR 11 when basic system initialization is
+ complete (which includes local file systems have been mounted), and the system begins starting regular
+ system services. (This string is extended at start of
+ <filename>systemd-pcrphase-sysinit.service</filename>.)</para></listitem>
+
+ <listitem><para><literal>ready</literal> is extended into PCR 11 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 is
+ supposed to act as barrier between the time where unprivileged regular users are still prohibited to
+ log in and where they are allowed to log in. (This string is extended at start of
+ <filename>systemd-pcrphase.service</filename>.)</para></listitem>
+
+ <listitem><para><literal>shutdown</literal> is extended into PCR 11 when system shutdown begins. It is
+ supposed to act as barrier between the time the system is fully up and running and where it is about to
+ shut down. (This string is extended at stop of
+ <filename>systemd-pcrphase.service</filename>.)</para></listitem>
+
+ <listitem><para><literal>final</literal> is extended into PCR 11 at the end of system shutdown. It is
+ supposed to act as barrier between the time the service manager still runs and when it transitions into
+ the final boot phase where service management is not available anymore. (This string is extended at
+ stop of <filename>systemd-pcrphase-sysinit.service</filename>.)</para></listitem>
+
+ </orderedlist>
+
+ <para>During a regular system lifecycle, the strings <literal>enter-initrd</literal> →
+ <literal>leave-initrd</literal> → <literal>sysinit</literal> → <literal>ready</literal> →
+ <literal>shutdown</literal> → <literal>final</literal> are extended into PCR 11, one after the
+ other.</para>
+
+ <para>Specific phases of the boot process may be referenced via the series of strings measured, separated
+ by colons (the "boot path"). For example, the boot 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 boot path for the 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 boot 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>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>The <filename>/usr/lib/systemd/system-pcrphase</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></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></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></listitem>
+ </varlistentry>
+
+ <xi:include href="standard-options.xml" xpointer="help" />
+ <xi:include href="standard-options.xml" xpointer="version" />
+
+ </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>
+ </para>
+ </refsect1>
+
+</refentry>