Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 388 insertions, 0 deletions

diff --git a/man/systemd-measure.xml b/man/systemd-measure.xml
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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-measure" xmlns:xi="http://www.w3.org/2001/XInclude" conditional='ENABLE_BOOTLOADER'>
+
+  <refentryinfo>
+    <title>systemd-measure</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>systemd-measure</refentrytitle>
+    <manvolnum>1</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>systemd-measure</refname>
+    <refpurpose>Pre-calculate and sign expected TPM2 PCR values for booted unified kernel images</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <cmdsynopsis>
+      <command>/usr/lib/systemd/systemd-measure <arg choice="opt" rep="repeat">OPTIONS</arg></command>
+    </cmdsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Note: this command is experimental for now. While it is likely to become a regular component of
+    systemd, it might still change in behaviour and interface.</para>
+
+    <para><command>systemd-measure</command> is a tool that may be used to pre-calculate and sign the
+    expected TPM2 PCR 11 values that should be seen when a Linux <ulink
+    url="https://uapi-group.org/specifications/specs/unified_kernel_image/">Unified Kernel Image
+    (UKI)</ulink> based on
+    <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> is
+    booted up. It accepts paths to the ELF kernel image file, initrd image file, devicetree file, kernel
+    command line file,
+    <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry> file, boot
+    splash file, and TPM2 PCR PEM public key file that make up the unified kernel image, and determines the
+    PCR values expected to be in place after booting the image. Calculation starts with a zero-initialized
+    PCR 11, and is executed in a fashion compatible with what <filename>systemd-stub</filename> does at boot.
+    The result may optionally be signed cryptographically, to allow TPM2 policies that can only be unlocked
+    if a certain set of kernels is booted, for which such a PCR signature can be provided.</para>
+
+    <para>It usually doesn't make sense to call this tool directly when constructing a UKI. Instead,
+    <citerefentry><refentrytitle>ukify</refentrytitle><manvolnum>1</manvolnum></citerefentry> should be used;
+    it will invoke <command>systemd-measure</command> and take care of embedding the resulting measurements
+    into the UKI.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Commands</title>
+
+    <para>The following commands are understood:</para>
+
+    <variablelist>
+      <varlistentry>
+        <term><command>status</command></term>
+
+        <listitem><para>This is the default command if none is specified. This queries the local system's
+        TPM2 PCR 11+12+13 values and displays them. The data is written in a similar format as the
+        <command>calculate</command> command below, and may be used to quickly compare expectation with
+        reality.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><command>calculate</command></term>
+
+        <listitem><para>Pre-calculate the expected values seen in PCR register 11 after boot-up of a unified
+        kernel image consisting of the components specified with <option>--linux=</option>,
+        <option>--osrel=</option>, <option>--cmdline=</option>, <option>--initrd=</option>,
+        <option>--splash=</option>, <option>--dtb=</option>, <option>--uname=</option>,
+        <option>--sbat=</option>, <option>--pcrpkey=</option> see below. Only <option>--linux=</option> is
+        mandatory. (Alternatively, specify <option>--current</option> to use the current values of PCR
+        register 11 instead.)</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><command>sign</command></term>
+
+        <listitem><para>As with the <command>calculate</command> command, pre-calculate the expected value
+        seen in TPM2 PCR register 11 after boot-up of a unified kernel image. Then, cryptographically sign
+        the resulting values with the private/public key pair (RSA) configured via
+        <option>--private-key=</option> and <option>--public-key=</option>. This will write a JSON object to
+        standard output that contains signatures for all specified PCR banks (see the
+        <option>--bank=</option> option below), which may be used to unlock encrypted credentials (see
+        <citerefentry><refentrytitle>systemd-creds</refentrytitle><manvolnum>1</manvolnum></citerefentry>) or
+        LUKS volumes (see
+        <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>).
+        This allows binding secrets to a set of kernels for which such PCR 11 signatures can be
+        provided.</para>
+
+        <para>Note that a TPM2 device must be available for this signing to take place, even though the
+        result is not tied to any TPM2 device or its state.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Options</title>
+
+    <para>The following options are understood:</para>
+
+    <variablelist>
+      <varlistentry>
+        <term><option>--linux=<replaceable>PATH</replaceable></option></term>
+        <term><option>--osrel=<replaceable>PATH</replaceable></option></term>
+        <term><option>--cmdline=<replaceable>PATH</replaceable></option></term>
+        <term><option>--initrd=<replaceable>PATH</replaceable></option></term>
+        <term><option>--splash=<replaceable>PATH</replaceable></option></term>
+        <term><option>--dtb=<replaceable>PATH</replaceable></option></term>
+        <term><option>--uname=<replaceable>PATH</replaceable></option></term>
+        <term><option>--sbat=<replaceable>PATH</replaceable></option></term>
+        <term><option>--pcrpkey=<replaceable>PATH</replaceable></option></term>
+
+        <listitem><para>When used with the <command>calculate</command> or <command>sign</command> verb,
+        configures the files to read the unified kernel image components from. Each option corresponds with
+        the equally named section in the unified kernel PE file. The <option>--linux=</option> switch expects
+        the path to the ELF kernel file that the unified PE kernel will wrap. All switches except
+        <option>--linux=</option> are optional. Each option may be used at most once.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--current</option></term>
+        <listitem><para>When used with the <command>calculate</command> or <command>sign</command> verb,
+        takes the PCR 11 values currently in effect for the system (which should typically reflect the hashes
+        of the currently booted kernel). This can be used in place of <option>--linux=</option> and the other
+        switches listed above.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--bank=<replaceable>DIGEST</replaceable></option></term>
+
+        <listitem><para>Controls the PCR banks to pre-calculate the PCR values for – in case
+        <command>calculate</command> or <command>sign</command> is invoked –, or the banks to show in the
+        <command>status</command> output. May be used more then once to specify multiple banks. If not
+        specified, defaults to the four banks <literal>sha1</literal>, <literal>sha256</literal>,
+        <literal>sha384</literal>, <literal>sha512</literal>.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--private-key=<replaceable>PATH</replaceable></option></term>
+        <term><option>--public-key=<replaceable>PATH</replaceable></option></term>
+
+        <listitem><para>These switches take paths to a pair of PEM encoded RSA key files, for use with
+        the <command>sign</command> command.</para>
+
+        <para>Note the difference between the <option>--pcrpkey=</option> and <option>--public-key=</option>
+        switches. The former selects the data to include in the <literal>.pcrpkey</literal> PE section of the
+        unified kernel image, the latter picks the public key of the key pair used to sign the resulting PCR
+        11 values. The former is the key that the booted system will likely use to lock disk and credential
+        encryption to, the latter is the key used for unlocking such resources again. Hence, typically the
+        same PEM key should be supplied in both cases.</para>
+
+        <para>If the <option>--public-key=</option> is not specified but <option>--private-key=</option> is
+        specified the public key is automatically derived from the private key.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></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>--phase=</option><replaceable>PHASE</replaceable></term>
+
+        <listitem><para>Controls which boot phases to calculate expected PCR 11 values for. This takes a
+        series of colon-separated strings that encode boot "paths" for entering a specific phase of the boot
+        process. Each of the specified strings is measured by the
+        <filename>systemd-pcrphase-initrd.service</filename>,
+        <filename>systemd-pcrphase-sysinit.service</filename>, and
+        <citerefentry><refentrytitle>systemd-pcrphase.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        into PCR 11 during different milestones of the boot process. This switch may be specified multiple
+        times to calculate PCR values for multiple boot phases at once. If not used defaults to
+        <literal>enter-initrd</literal>, <literal>enter-initrd:leave-initrd</literal>,
+        <literal>enter-initrd:leave-initrd:sysinit</literal>,
+        <literal>enter-initrd:leave-initrd:sysinit:ready</literal>, i.e. calculates expected PCR values for
+        the boot phase in the initrd, during early boot, during later boot, and during system runtime, but
+        excluding the phases before the initrd or when shutting down. This setting is honoured both by
+        <command>calculate</command> and <command>sign</command>. When used with the latter it's particularly
+        useful for generating PCR signatures that can only be used for unlocking resources during specific
+        parts of the boot process.</para>
+
+        <para>For further details about PCR boot phases, see
+        <citerefentry><refentrytitle>systemd-pcrphase.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+
+        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--append=</option><replaceable>PATH</replaceable></term>
+
+        <listitem><para>When generating a PCR JSON signature (via the <command>sign</command> command),
+        combine it with a previously generated PCR JSON signature, and output it as one. The specified path
+        must refer to a regular file that contains a valid JSON PCR signature object. The specified file is
+        not modified. It will be read first, then the newly generated signature appended to it, and the
+        resulting object is written to standard output. Use this to generate a single JSON object consisting
+        from signatures made with a number of signing keys (for example, to have one key per boot phase). The
+        command will suppress duplicates: if a specific signature is already included in a JSON signature
+        object it is not added a second time.</para>
+
+        <xi:include href="version-info.xml" xpointer="v253"/></listitem>
+      </varlistentry>
+
+      <xi:include href="standard-options.xml" xpointer="json" />
+      <xi:include href="standard-options.xml" xpointer="no-pager" />
+      <xi:include href="standard-options.xml" xpointer="help" />
+      <xi:include href="standard-options.xml" xpointer="version" />
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Examples</title>
+
+    <example>
+      <title>Generate a unified kernel image, and calculate the expected TPM PCR 11 value</title>
+
+      <programlisting>$ ukify --output=vmlinux.efi \
+     --os-release=@os-release.txt \
+     --cmdline=@cmdline.txt \
+     --splash=splash.bmp \
+     --devicetree=devicetree.dtb \
+     --measure \
+     vmlinux initrd.cpio
+11:sha1=d775a7b4482450ac77e03ee19bda90bd792d6ec7
+11:sha256=bc6170f9ce28eb051ab465cd62be8cf63985276766cf9faf527ffefb66f45651
+11:sha384=1cf67dff4757e61e5...7f49ad720be02fd07263e1f93061243aec599d1ee4b4
+11:sha512=8e79acd3ddbbc8282...0c3e8ec0c714821032038f525f744960bcd082d937da
+</programlisting>
+
+      <para><citerefentry><refentrytitle>ukify</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+      internally calls <command>systemd-measure</command>. The output with hashes is from
+      <command>systemd-measure</command>.</para>
+    </example>
+
+    <example>
+      <title>Generate a private/public key pair, a unified kernel image, and a TPM PCR 11 signature for
+      it, and embed the signature and the public key in the image</title>
+
+      <programlisting>$ openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out tpm2-pcr-private.pem
+..+.+++++++++......+.........+......+.......+....+.....+.+...+..........
+$ openssl rsa -pubout -in tpm2-pcr-private.pem -out tpm2-pcr-public.pem
+# systemd-measure sign \
+     --linux=vmlinux \
+     --osrel=os-release.txt \
+     --cmdline=cmdline.txt \
+     --initrd=initrd.cpio \
+     --splash=splash.bmp \
+     --dtb=devicetree.dtb \
+     --pcrpkey=tpm2-pcr-public.pem \
+     --bank=sha1 \
+     --bank=sha256 \
+     --private-key=tpm2-pcr-private.pem \
+     --public-key=tpm2-pcr-public.pem >tpm2-pcr-signature.json
+# ukify --output=vmlinuz.efi \
+     --os-release=@os-release.txt \
+     --cmdline=@cmdline.txt \
+     --splash=splash.bmp \
+     --devicetree=devicetree.dtb \
+     --pcr-private-key=tpm2-pcr-private.pem \
+     --pcr-public-key=tpm2-pcr-public.pem \
+     --pcr-banks=sha1,sha256 \
+     vmlinux initrd.cpio</programlisting>
+
+     <para>Later on, enroll the signed PCR policy on a LUKS volume:</para>
+
+     <programlisting># systemd-cryptenroll --tpm2-device=auto \
+     --tpm2-public-key=tpm2-pcr-public.pem \
+     --tpm2-signature=tpm2-pcr-signature.json \
+     /dev/sda5</programlisting>
+
+     <para>And then unlock the device with the signature:</para>
+
+     <programlisting># systemd-cryptsetup attach \
+     volume5 /dev/sda5 - \
+     tpm2-device=auto,tpm2-signature=/path/to/tpm2-pcr-signature.json</programlisting>
+
+     <para>Note that when the generated unified kernel image <filename>vmlinux.efi</filename> is booted, the
+     signature and public key files will be placed at locations <command>systemd-cryptenroll</command> and
+     <command>systemd-cryptsetup</command> will look for anyway, and thus these paths do not actually need to
+     be specified.</para>
+    </example>
+
+    <example>
+      <title>Introduce a second public key, signing the same kernel PCR measurements, but only for the initrd boot phase</title>
+
+      <para>This example extends the previous one, but we now introduce a second signing key that is only
+      used to sign PCR policies restricted to the initrd boot phase. This can be used to lock down root
+      volumes in a way that they can only be unlocked before the transition to the host system. Thus we have
+      two classes of secrets or credentials: one that can be unlocked during the entire runtime, and the
+      other that can only be used in the initrd.</para>
+
+      <programlisting>$ openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out tpm2-pcr-private.pem
+.+........+.+........+.......+...+...+........+....+......+..+..........
+$ openssl rsa -pubout -in tpm2-pcr-private.pem -out tpm2-pcr-public.pem
+$ openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out tpm2-pcr-initrd-private.pem
+..+.......++........+........+......+........+....+.....+.+..+..........
+$ openssl rsa -pubout -in tpm2-pcr-initrd-private.pem -out tpm2-pcr-initrd-public.pem
+# ukify --output vmlinux-1.2.3.efi \
+     --os-release=@os-release.txt \
+     --cmdline=@cmdline.txt \
+     --splash=splash.bmp \
+     --devicetree=devicetree.dtb \
+     --pcr-private-key=tpm2-pcr-private.pem \
+     --pcr-public-key=tpm2-pcr-public.pem \
+     --phases=enter-initrd,enter-initrd:leave-initrd,enter-initrd:leave-initrd:sysinit,enter-initrd:leave-initrd:sysinit:ready \
+     --pcr-banks=sha1,sha256 \
+     --pcr-private-key=tpm2-pcr-initrd-private.pem \
+     --pcr-public-key=tpm2-pcr-initrd-public.pem \
+     --phases=enter-initrd \
+     vmlinux-1.2.3 initrd.cpio \
+     --uname=1.2.3
++ /usr/lib/systemd/systemd-measure sign --linux=vmlinux-1.2.3 \
+--osrel=os-release.txt --cmdline=cmdline.txt --dtb=devicetree.dtb \
+--splash=splash.bmp --initrd=initrd.cpio --bank=sha1 --bank=sha256 \
+--private-key=tpm2-pcr-private.pem --public-key=tpm2-pcr-public.pem \
+--phase=enter-initrd --phase=enter-initrd:leave-initrd \
+--phase=enter-initrd:leave-initrd:sysinit \
+--phase=enter-initrd:leave-initrd:sysinit:ready
++ /usr/lib/systemd/systemd-measure sign --linux=vmlinux-1.2.3 \
+--osrel=os-release.txt --cmdline=cmdline.txt --dtb=devicetree.dtb \
+--splash=splash.bmp --initrd=initrd.cpio --bank=sha1 --bank=sha256 \
+--private-key=tpm2-pcr-initrd-private.pem \
+--public-key=tpm2-pcr-initrd-public.pem \
+--phase=enter-initrd
+Wrote unsigned vmlinux-1.2.3.efi
+      </programlisting>
+
+      <para><command>ukify</command> prints out both invocations of <command>systemd-measure</command> as
+      informative output (the lines starting with <literal>+</literal>); this allows us to see how
+      <command>systemd-measure</command> is called. It then merges the output of both invocations into the
+      <literal>.pcrsig</literal> section. <command>systemd-measure</command> may also do this merge itself
+      using the <option>--append=</option> option.</para>
+
+      <para>Note that in this example the <literal>.pcrpkey</literal> PE section contains the key specified
+      by the first <option>--pcr-private-key=</option> option, covering all boot phases. The
+      <literal>.pcrpkey</literal> section is used in the default policies of
+      <command>systemd-cryptenroll</command> and <command>systemd-creds</command>. To use the stricter policy
+      bound to <filename>tpm-pcr-initrd-public.pem</filename>, specify <option>--tpm2-public-key=</option> on
+      the command line of those tools.</para>
+    </example>
+  </refsect1>
+
+  <refsect1>
+    <title>Exit status</title>
+
+    <para>On success, 0 is returned, a non-zero failure code otherwise.</para>
+  </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>ukify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-creds</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-pcrphase.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+     </para>
+  </refsect1>
+
+</refentry>