a8574d0055
Adds support for LUKS detached header device on kernel
command line. It's introduced via extension to existing
luks.options 'header=' argument beyond colon (see examples
below). If LUKS header device is specified it's expected
to contain filesystem with LUKS header image on a path
specified in the first part of header specification.
The second parameter 'luks.data' specifies LUKS data device
supposed to be paired with detached LUKS header (note that
encrypted LUKS data device with detached header is unrecognisable
by standard blkid probe).
This adds support for LUKS encrypted rootfs partition with
detached header. It can also be used for initializing online LUKS2
encryption of data device.
Examples:
luks.data=<luks_uuid>=/dev/sdz
luks.data=<luks_uuid>=/dev/vg/lv
luks.data=<luks_uuid>=/dev/mapper/lv
luks.data=<luks_uuid>=PARTUUID=<part_uuid>
luks.data=<luks_uuid>=PARTLABEL=<part_uuid>
luks.options=<luks_uuid>=header=/header/path:UUID=<fs_uuid>
luks.options=<luks_uuid>=header=/header/path:PARTUUID=<part_uuid>
luks.options=<luks_uuid>=header=/header/path:PARTLABEL=<part_label>
luks.options=<luks_uuid>=header=/header/path:LABEL=<fs_label>
luks.options=<luks_uuid>=header=/header/path:/dev/sdx
luks.options=<luks_uuid>=header=/header/path:/dev/vg/lv
The '/header/path' is considered to be relative location within
filesystem residing on the header device specified beyond colon
character
237 lines
11 KiB
XML
237 lines
11 KiB
XML
<?xml version="1.0"?>
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<!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="systemd-cryptsetup-generator" conditional='HAVE_LIBCRYPTSETUP'>
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<refentryinfo>
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<title>systemd-cryptsetup-generator</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-cryptsetup-generator</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-cryptsetup-generator</refname>
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<refpurpose>Unit generator for <filename>/etc/crypttab</filename></refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/usr/lib/systemd/system-generators/systemd-cryptsetup-generator</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-cryptsetup-generator</filename> is a
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generator that translates <filename>/etc/crypttab</filename> into
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native systemd units early at boot and when configuration of the
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system manager is reloaded. This will create
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<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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units as necessary.</para>
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<para><filename>systemd-cryptsetup-generator</filename> implements
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<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Kernel Command Line</title>
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<para><filename>systemd-cryptsetup-generator</filename>
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understands the following kernel command line parameters:</para>
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<variablelist class='kernel-commandline-options'>
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<varlistentry>
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<term><varname>luks=</varname></term>
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<term><varname>rd.luks=</varname></term>
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<listitem><para>Takes a boolean argument. Defaults to
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<literal>yes</literal>. If <literal>no</literal>, disables the
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generator entirely. <varname>rd.luks=</varname> is honored
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only by initial RAM disk (initrd) while
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<varname>luks=</varname> is honored by both the main system
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and the initrd. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.crypttab=</varname></term>
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<term><varname>rd.luks.crypttab=</varname></term>
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<listitem><para>Takes a boolean argument. Defaults to
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<literal>yes</literal>. If <literal>no</literal>, causes the
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generator to ignore any devices configured in
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<filename>/etc/crypttab</filename>
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(<varname>luks.uuid=</varname> will still work however).
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<varname>rd.luks.crypttab=</varname> is honored only by
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initial RAM disk (initrd) while
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<varname>luks.crypttab=</varname> is honored by both the main
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system and the initrd. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.uuid=</varname></term>
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<term><varname>rd.luks.uuid=</varname></term>
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<listitem><para>Takes a LUKS superblock UUID as argument. This
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will activate the specified device as part of the boot process
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as if it was listed in <filename>/etc/crypttab</filename>.
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This option may be specified more than once in order to set up
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multiple devices. <varname>rd.luks.uuid=</varname> is honored
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only by initial RAM disk (initrd) while
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<varname>luks.uuid=</varname> is honored by both the main
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system and the initrd.</para>
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<para>If /etc/crypttab contains entries with the same UUID,
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then the name, keyfile and options specified there will be
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used. Otherwise, the device will have the name
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<literal>luks-UUID</literal>.</para>
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<para>If /etc/crypttab exists, only those UUIDs
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specified on the kernel command line
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will be activated in the initrd or the real root.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.name=</varname></term>
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<term><varname>rd.luks.name=</varname></term>
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<listitem><para>Takes a LUKS super block UUID followed by an
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<literal>=</literal> and a name. This implies
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<varname>rd.luks.uuid=</varname> or
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<varname>luks.uuid=</varname> and will additionally make the
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LUKS device given by the UUID appear under the provided
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name.</para>
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<para>This parameter is the analogue of the first <citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> field <replaceable>volume-name</replaceable>.</para>
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<para><varname>rd.luks.name=</varname> is honored only by
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initial RAM disk (initrd) while <varname>luks.name=</varname>
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is honored by both the main system and the initrd.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.data=</varname></term>
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<term><varname>rd.luks.data=</varname></term>
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<listitem><para>Takes a LUKS super block UUID followed by a <literal>=</literal> and a block device
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specification for device hosting encrypted data.</para>
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<para>For those entries specified with <varname>rd.luks.uuid=</varname> or
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<varname>luks.uuid=</varname>, the data device will be set to the one specified by
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<varname>rd.luks.data=</varname> or <varname>luks.data=</varname> of the corresponding UUID.</para>
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<para>LUKS data device parameter is usefull for specifying encrypted data devices with detached headers specified in
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<varname>luks.options</varname> entry containing <literal>header=</literal> argument. For example,
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<varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
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<varname>rd.luks.options=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/path/to/luks.hdr
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<varname>rd.luks.data=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx.
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Hence, in this case, we will attempt to unlock LUKS device assembled from data device <literal>/dev/sdx</literal>
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and LUKS header (metadata) put in <literal>/path/to/luks.hdr</literal> file. This syntax is for now
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only supported on a per-device basis, i.e. you have to specify LUKS device UUID.</para>
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<para>This parameter is the analogue of the second <citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> field <replaceable>encrypted-device</replaceable>.</para>
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<para><varname>rd.luks.data=</varname> is honored only by initial RAM disk (initrd) while
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<varname>luks.data=</varname> is honored by both the main system and the initrd.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.key=</varname></term>
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<term><varname>rd.luks.key=</varname></term>
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<listitem><para>Takes a password file name as argument or a
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LUKS super block UUID followed by a <literal>=</literal> and a
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password file name.</para>
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<para>For those entries specified with
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<varname>rd.luks.uuid=</varname> or
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<varname>luks.uuid=</varname>, the password file will be set
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to the one specified by <varname>rd.luks.key=</varname> or
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<varname>luks.key=</varname> of the corresponding UUID, or the
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password file that was specified without a UUID.</para>
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<para>It is also possible to specify an external device which
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should be mounted before we attempt to unlock the LUKS device.
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systemd-cryptsetup will use password file stored on that
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device. Device containing password file is specified by
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appending colon and a device identifier to the password file
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path. For example,
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<varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
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<varname>rd.luks.key=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/keyfile:LABEL=keydev.
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Hence, in this case, we will attempt to mount file system
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residing on the block device with label <literal>keydev</literal>.
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This syntax is for now only supported on a per-device basis,
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i.e. you have to specify LUKS device UUID.</para>
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<para>This parameter is the analogue of the third <citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> field <replaceable>key-file</replaceable>.</para>
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<para><varname>rd.luks.key=</varname>
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is honored only by initial RAM disk
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(initrd) while
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<varname>luks.key=</varname> is
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honored by both the main system and
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the initrd.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>luks.options=</varname></term>
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<term><varname>rd.luks.options=</varname></term>
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<listitem><para>Takes a LUKS super block UUID followed by an
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<literal>=</literal> and a string of options separated by
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commas as argument. This will override the options for the
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given UUID.</para>
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<para>If only a list of options, without an UUID, is
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specified, they apply to any UUIDs not specified elsewhere,
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and without an entry in
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<filename>/etc/crypttab</filename>.</para>
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<para>This parameter is the analogue of the fourth <citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> field <replaceable>options</replaceable>.</para>
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<para>It is possible to specify an external device which
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should be mounted before we attempt to unlock the LUKS device.
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systemd-cryptsetup will assemble LUKS device by combining
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data device specified in <varname>luks.data</varname> with
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detached LUKS header found in <literal>header=</literal>
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argument. For example,
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<varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
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<varname>rd.luks.options=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/luks.hdr:LABEL=hdrdev
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<varname>rd.luks.data=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx.
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Hence, in this case, we will attempt to mount file system
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residing on the block device with label <literal>hdrdev</literal>, and look
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for <literal>luks.hdr</literal> on that file system. Said header will be used
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to unlock (decrypt) encrypted data stored on /dev/sdx.
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This syntax is for now only supported on a per-device basis,
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i.e. you have to specify LUKS device UUID.</para>
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<para><varname>rd.luks.options=</varname> is honored only by initial
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RAM disk (initrd) while <varname>luks.options=</varname> is
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honored by both the main system and the initrd.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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