systemd/man/systemd-cryptsetup-generator.xml

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<refentry id="systemd-cryptsetup-generator" conditional='HAVE_LIBCRYPTSETUP'>

  <refentryinfo>
    <title>systemd-cryptsetup-generator</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-cryptsetup-generator</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-cryptsetup-generator</refname>
    <refpurpose>Unit generator for <filename>/etc/crypttab</filename></refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>/usr/lib/systemd/system-generators/systemd-cryptsetup-generator</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><filename>systemd-cryptsetup-generator</filename> is a
    generator that translates <filename>/etc/crypttab</filename> into
    native systemd units early at boot and when configuration of the
    system manager is reloaded. This will create
    <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    units as necessary.</para>

    <para><filename>systemd-cryptsetup-generator</filename> implements
    <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  </refsect1>

  <refsect1>
    <title>Kernel Command Line</title>

    <para><filename>systemd-cryptsetup-generator</filename>
    understands the following kernel command line parameters:</para>

    <variablelist class='kernel-commandline-options'>
      <varlistentry>
        <term><varname>luks=</varname></term>
        <term><varname>rd.luks=</varname></term>

        <listitem><para>Takes a boolean argument. Defaults to
        <literal>yes</literal>. If <literal>no</literal>, disables the
        generator entirely. <varname>rd.luks=</varname> is honored
        only by initial RAM disk (initrd) while
        <varname>luks=</varname> is honored by both the main system
        and the initrd. </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.crypttab=</varname></term>
        <term><varname>rd.luks.crypttab=</varname></term>

        <listitem><para>Takes a boolean argument. Defaults to
        <literal>yes</literal>. If <literal>no</literal>, causes the
        generator to ignore any devices configured in
        <filename>/etc/crypttab</filename>
        (<varname>luks.uuid=</varname> will still work however).
        <varname>rd.luks.crypttab=</varname> is honored only by
        initial RAM disk (initrd) while
        <varname>luks.crypttab=</varname> is honored by both the main
        system and the initrd. </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.uuid=</varname></term>
        <term><varname>rd.luks.uuid=</varname></term>

        <listitem><para>Takes a LUKS superblock UUID as argument. This
        will activate the specified device as part of the boot process
        as if it was listed in <filename>/etc/crypttab</filename>.
        This option may be specified more than once in order to set up
        multiple devices. <varname>rd.luks.uuid=</varname> is honored
        only by initial RAM disk (initrd) while
        <varname>luks.uuid=</varname> is honored by both the main
        system and the initrd.</para>
        <para>If /etc/crypttab contains entries with the same UUID,
        then the name, keyfile and options specified there will be
        used. Otherwise, the device will have the name
        <literal>luks-UUID</literal>.</para>
        <para>If /etc/crypttab exists, only those UUIDs
        specified on the kernel command line
        will be activated in the initrd or the real root.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.name=</varname></term>
        <term><varname>rd.luks.name=</varname></term>

        <listitem><para>Takes a LUKS super block UUID followed by an
        <literal>=</literal> and a name. This implies
        <varname>rd.luks.uuid=</varname> or
        <varname>luks.uuid=</varname> and will additionally make the
        LUKS device given by the UUID appear under the provided
        name.</para>

        <para>This parameter is the analogue of the first <citerefentry><refentrytitle>crypttab</refentrytitle>
        <manvolnum>5</manvolnum></citerefentry> field <replaceable>volume-name</replaceable>.</para>

        <para><varname>rd.luks.name=</varname> is honored only by
        initial RAM disk (initrd) while <varname>luks.name=</varname>
        is honored by both the main system and the initrd.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.data=</varname></term>
        <term><varname>rd.luks.data=</varname></term>

        <listitem><para>Takes a LUKS super block UUID followed by a <literal>=</literal> and a block device
        specification for device hosting encrypted data.</para>

        <para>For those entries specified with <varname>rd.luks.uuid=</varname> or
        <varname>luks.uuid=</varname>, the data device will be set to the one specified by
        <varname>rd.luks.data=</varname> or <varname>luks.data=</varname> of the corresponding UUID.</para>

        <para>LUKS data device parameter is useful for specifying encrypted data devices with detached headers specified in
        <varname>luks.options</varname> entry containing <literal>header=</literal> argument. For example,
        <varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
        <varname>rd.luks.options=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/path/to/luks.hdr
        <varname>rd.luks.data=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx.
        Hence, in this case, we will attempt to unlock LUKS device assembled from data device <literal>/dev/sdx</literal>
        and LUKS header (metadata) put in <literal>/path/to/luks.hdr</literal> file. This syntax is for now
        only supported on a per-device basis, i.e. you have to specify LUKS device UUID.</para>

        <para>This parameter is the analogue of the second <citerefentry><refentrytitle>crypttab</refentrytitle>
        <manvolnum>5</manvolnum></citerefentry> field <replaceable>encrypted-device</replaceable>.</para>

        <para><varname>rd.luks.data=</varname> is honored only by initial RAM disk (initrd) while
        <varname>luks.data=</varname> is honored by both the main system and the initrd.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.key=</varname></term>
        <term><varname>rd.luks.key=</varname></term>

        <listitem><para>Takes a password file name as argument or a
        LUKS super block UUID followed by a <literal>=</literal> and a
        password file name.</para>

        <para>For those entries specified with
        <varname>rd.luks.uuid=</varname> or
        <varname>luks.uuid=</varname>, the password file will be set
        to the one specified by <varname>rd.luks.key=</varname> or
        <varname>luks.key=</varname> of the corresponding UUID, or the
        password file that was specified without a UUID.</para>

        <para>It is also possible to specify an external device which
        should be mounted before we attempt to unlock the LUKS device.
        systemd-cryptsetup will use password file stored on that
        device. Device containing password file is specified by
        appending colon and a device identifier to the password file
        path. For example,
        <varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
        <varname>rd.luks.key=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/keyfile:LABEL=keydev.
        Hence, in this case, we will attempt to mount file system
        residing on the block device with label <literal>keydev</literal>.
        This syntax is for now only supported on a per-device basis,
        i.e. you have to specify LUKS device UUID.</para>

        <para>This parameter is the analogue of the third <citerefentry><refentrytitle>crypttab</refentrytitle>
        <manvolnum>5</manvolnum></citerefentry> field <replaceable>key-file</replaceable>.</para>

        <para><varname>rd.luks.key=</varname>
        is honored only by initial RAM disk
        (initrd) while
        <varname>luks.key=</varname> is
        honored by both the main system and
        the initrd.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks.options=</varname></term>
        <term><varname>rd.luks.options=</varname></term>

        <listitem><para>Takes a LUKS super block UUID followed by an
        <literal>=</literal> and a string of options separated by
        commas as argument. This will override the options for the
        given UUID.</para>
        <para>If only a list of options, without an UUID, is
        specified, they apply to any UUIDs not specified elsewhere,
        and without an entry in
        <filename>/etc/crypttab</filename>.</para>

        <para>This parameter is the analogue of the fourth <citerefentry><refentrytitle>crypttab</refentrytitle>
        <manvolnum>5</manvolnum></citerefentry> field <replaceable>options</replaceable>.</para>

        <para>It is possible to specify an external device which
        should be mounted before we attempt to unlock the LUKS device.
        systemd-cryptsetup will assemble LUKS device by combining
        data device specified in <varname>luks.data</varname> with
        detached LUKS header found in <literal>header=</literal>
        argument. For example,
        <varname>rd.luks.uuid=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40
        <varname>rd.luks.options=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/luks.hdr:LABEL=hdrdev
        <varname>rd.luks.data=</varname>b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx.
        Hence, in this case, we will attempt to mount file system
        residing on the block device with label <literal>hdrdev</literal>, and look
        for <literal>luks.hdr</literal> on that file system. Said header will be used
        to unlock (decrypt) encrypted data stored on /dev/sdx.
        This syntax is for now only supported on a per-device basis,
        i.e. you have to specify LUKS device UUID.</para>

        <para><varname>rd.luks.options=</varname> is honored only by initial
        RAM disk (initrd) while <varname>luks.options=</varname> is
        honored by both the main system and the initrd.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-cryptenroll</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>