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| <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
| <refentry id="ukify" xmlns:xi="http://www.w3.org/2001/XInclude" conditional='ENABLE_UKIFY'> |
| |
| <refentryinfo> |
| <title>ukify</title> |
| <productname>systemd</productname> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>ukify</refentrytitle> |
| <manvolnum>1</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>ukify</refname> |
| <refpurpose>Combine kernel and initrd into a signed Unified Kernel Image</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <cmdsynopsis> |
| <command>/usr/lib/systemd/ukify</command> |
| <arg choice="plain"><replaceable>LINUX</replaceable></arg> |
| <arg choice="plain" rep="repeat"><replaceable>INITRD</replaceable></arg> |
| <arg choice="opt" rep="repeat">OPTIONS</arg> |
| </cmdsynopsis> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>Note: this command is experimental for now. While it is intended to become a regular component of |
| systemd, it might still change in behaviour and interface.</para> |
| |
| <para><command>ukify</command> is a tool that combines a kernel and an initrd with |
| a UEFI boot stub to create a |
| <ulink url="https://uapi-group.org/specifications/specs/unified_kernel_image/">Unified Kernel Image (UKI)</ulink> |
| — a PE binary that can be executed by the firmware to start the embedded linux kernel. |
| See <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
| for details about the stub.</para> |
| |
| <para>Additional sections will be inserted into the UKI, either automatically or only if a specific |
| option is provided. See the discussions of |
| <option>--cmdline=</option>, |
| <option>--os-release=</option>, |
| <option>--devicetree=</option>, |
| <option>--splash=</option>, |
| <option>--pcrpkey=</option>, |
| <option>--uname=</option>, |
| and <option>--section=</option> |
| below.</para> |
| |
| <para>If PCR signing keys are provided via the <option>--pcr-public-key=</option> and |
| <option>--pcr-private-key=</option> options, PCR values that will be seen after booting with the given |
| kernel, initrd, and other sections, will be calculated, signed, and embedded in the UKI. |
| <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry> is |
| used to perform this calculation and signing.</para> |
| |
| <para>The calculation of PCR values is done for specific boot phase paths. Those can be specified with |
| <option>--phases=</option> option. If not specified, the default provided by |
| <command>systemd-measure</command> is used. It is also possible to specify the |
| <option>--pcr-private-key=</option>, <option>--pcr-public-key=</option>, and <option>--phases=</option> |
| arguments more than once. Signatures will be then performed with each of the specified keys. When both |
| <option>--phases=</option> and <option>--pcr-private-key=</option> are used, they must be specified the |
| same number of times, and then the n-th boot phase path set will be signed by the n-th key. This can be |
| used to build different trust policies for different phases of the boot.</para> |
| |
| <para>If a SecureBoot signing key is provided via the <option>--secureboot-private-key=</option> option, |
| the resulting PE binary will be signed as a whole, allowing the resulting UKI to be trusted by |
| SecureBoot. Also see the discussion of automatic enrollment in |
| <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>. |
| </para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Options</title> |
| |
| <para>Note that the <replaceable>LINUX</replaceable> positional argument is mandatory. The |
| <replaceable>INITRD</replaceable> positional arguments are optional. If more than one is specified, they |
| will all be combined into a single PE section. This is useful to for example prepend microcode before the |
| actual initrd.</para> |
| |
| <para>The following options are understood:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><option>--cmdline=<replaceable>TEXT</replaceable>|<replaceable>@PATH</replaceable></option></term> |
| |
| <listitem><para>Specify the kernel command line (the <literal>.cmdline</literal> section). The |
| argument may be a literal string, or <literal>@</literal> followed by a path name. If not specified, |
| no command line will be embedded.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--os-release=<replaceable>TEXT</replaceable>|<replaceable>@PATH</replaceable></option></term> |
| |
| <listitem><para>Specify the os-release description (the <literal>.osrel</literal> section). The |
| argument may be a literal string, or <literal>@</literal> followed by a path name. If not specified, |
| the <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| file will be picked up from the host system.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--devicetree=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>Specify the devicetree description (the <literal>.dtb</literal> section). The |
| argument is a path to a compiled binary DeviceTree file. If not specified, the section will not be |
| present.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--splash=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>Specify a picture to display during boot (the <literal>.splash</literal> section). |
| The argument is a path to a BMP file. If not specified, the section will not be present. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--pcrpkey=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>Specify a path to a public key to embed in the <literal>.pcrpkey</literal> section. |
| If not specified, and there's exactly one <option>--pcr-public-key=</option> argument, that key will |
| be used. Otherwise, the section will not be present.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--uname=<replaceable>VERSION</replaceable></option></term> |
| |
| <listitem><para>Specify the kernel version (as in <command>uname -r</command>, the |
| <literal>.uname</literal> section). If not specified, an attempt will be made to extract the version |
| string from the kernel image. It is recommended to pass this explicitly if known, because the |
| extraction is based on heuristics and not very reliable. If not specified and extraction fails, the |
| section will not be present.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--section=<replaceable>NAME</replaceable>:<replaceable>TEXT</replaceable>|<replaceable>@PATH</replaceable></option></term> |
| |
| <listitem><para>Specify an arbitrary additional section |
| <literal><replaceable>NAME</replaceable></literal>. Note that the name is used as-is, and if the |
| section name should start with a dot, it must be included in <replaceable>NAME</replaceable>. The |
| argument may be a literal string, or <literal>@</literal> followed by a path name. This option may be |
| specified more than once. Any sections specified in this fashion will be inserted (in order) before |
| the <literal>.linux</literal> section which is always last.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--pcr-private-key=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>Specify a private key to use for signing PCR policies. This option may be specified |
| more than once, in which case multiple signatures will be made.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--pcr-public-key=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>Specify a public key to use for signing PCR policies. This option may be specified |
| more than once, similarly to the <option>--pcr-private-key=</option> option. If not present, the |
| public keys will be extracted from the private keys. If present, the this option must be specified |
| the same number of times as the <option>--pcr-private-key=</option> option.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--phases=<replaceable>LIST</replaceable></option></term> |
| |
| <listitem><para>A comma or space-separated list of colon-separated phase paths to sign a policy for. |
| If not present, the default of |
| <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
| will be used. When this argument is present, it must appear the same number of times as the |
| <option>--pcr-private-key=</option> option. Each set of boot phase paths will be signed with the |
| corresponding private key.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--pcr-banks=<replaceable>PATH</replaceable></option></term> |
| |
| <listitem><para>A comma or space-separated list of PCR banks to sign a policy for. If not present, |
| all known banks will be used (<literal>sha1</literal>, <literal>sha256</literal>, |
| <literal>sha384</literal>, <literal>sha512</literal>), which will fail if not supported by the |
| system.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--secureboot-private-key=<replaceable>SB_KEY</replaceable></option></term> |
| |
| <listitem><para>A path to a private key to use for signing of the resulting binary. If the |
| <option>--signing-engine=</option> option is used, this may also be an engine-specific |
| designation.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--secureboot-certificate=<replaceable>SB_CERT</replaceable></option></term> |
| |
| <listitem><para>A path to a certificate to use for signing of the resulting binary. If the |
| <option>--signing-engine=</option> option is used, this may also be an engine-specific |
| designation.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--signing-engine=<replaceable>ENGINE</replaceable></option></term> |
| |
| <listitem><para>An "engine" to for signing of the resulting binary. This option is currently passed |
| verbatim to the <option>--engine=</option> option of |
| <citerefentry project='archlinux'><refentrytitle>sbsign</refentrytitle><manvolnum>1</manvolnum></citerefentry>. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--sign-kernel</option></term> |
| <term><option>--no-sign-kernel</option></term> |
| |
| <listitem><para>Override the detection of whether to sign the Linux binary itself before it is |
| embedded in the combined image. If not specified, it will be signed if a SecureBoot signing key is |
| provided via the <option>--secureboot-private-key=</option> option and the binary has not already |
| been signed. If <option>--sign-kernel</option> is specified, and the binary has already been signed, |
| the signature will be appended anyway.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--tools=<replaceable>DIRS</replaceable></option></term> |
| |
| <listitem><para>Specify one or more directories with helper tools. <command>ukify</command> will look |
| for helper tools in those directories first, and if not found, try to load them from |
| <varname>$PATH</varname> in the usual fashion.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--measure</option></term> |
| <term><option>--no-measure</option></term> |
| |
| <listitem><para>Enable or disable a call to <command>systemd-measure</command> to print |
| pre-calculated PCR values. Defaults to false.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--output=<replaceable>FILENAME</replaceable></option></term> |
| |
| <listitem><para>The output filename. If not specified, the name of the |
| <replaceable>LINUX</replaceable> argument, with the suffix <literal>.unsigned.efi</literal> or |
| <literal>.signed.efi</literal> will be used, depending on whether signing for SecureBoot was |
| performed.</para></listitem> |
| </varlistentry> |
| |
| <xi:include href="standard-options.xml" xpointer="help" /> |
| <xi:include href="standard-options.xml" xpointer="version" /> |
| </variablelist> |
| </refsect1> |
| |
| <refsect1> |
| <title>Examples</title> |
| |
| <example> |
| <title>Minimal invocation</title> |
| |
| <programlisting>ukify \ |
| /lib/modules/6.0.9-300.fc37.x86_64/vmlinuz \ |
| /some/path/initramfs-6.0.9-300.fc37.x86_64.img \ |
| --cmdline='quiet rw' |
| </programlisting> |
| |
| <para>This creates an unsigned UKI <filename>./vmlinuz.unsigned.efi</filename>.</para> |
| </example> |
| |
| <example> |
| <title>All the bells and whistles</title> |
| |
| <programlisting>/usr/lib/systemd/ukify \ |
| /lib/modules/6.0.9-300.fc37.x86_64/vmlinuz \ |
| early_cpio \ |
| /some/path/initramfs-6.0.9-300.fc37.x86_64.img \ |
| --pcr-private-key=pcr-private-initrd-key.pem \ |
| --pcr-public-key=pcr-public-initrd-key.pem \ |
| --phases='enter-initrd' \ |
| --pcr-private-key=pcr-private-system-key.pem \ |
| --pcr-public-key=pcr-public-system-key.pem \ |
| --phases='enter-initrd:leave-initrd enter-initrd:leave-initrd:sysinit \ |
| enter-initrd:leave-initrd:sysinit:ready' \ |
| --pcr-banks=sha384,sha512 \ |
| --secureboot-private-key=sb.key \ |
| --secureboot-certificate=sb.cert \ |
| --sign-kernel \ |
| --cmdline='quiet rw rhgb' |
| </programlisting> |
| |
| <para>This creates a signed UKI <filename index='false'>./vmlinuz.signed.efi</filename>. |
| The initrd section contains two concatenated parts, <filename index='false'>early_cpio</filename> |
| and <filename index='false'>initramfs-6.0.9-300.fc37.x86_64.img</filename>. |
| The policy embedded in the <literal>.pcrsig</literal> section will be signed for the initrd (the |
| <constant>enter-initrd</constant> phase) with the key |
| <filename index='false'>pcr-private-initrd-key.pem</filename>, and for the main system (phases |
| <constant>leave-initrd</constant>, <constant>sysinit</constant>, <constant>ready</constant>) with the |
| key <filename index='false'>pcr-private-system-key.pem</filename>. The Linux binary and the resulting |
| combined image will be signed with the SecureBoot key <filename index='false'>sb.key</filename>.</para> |
| </example> |
| </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-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| <citerefentry project='man-pages'><refentrytitle>objcopy</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-pcrphase.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |