<?xml version="1.0"?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> <refentry id="systemd-cryptsetup" conditional='HAVE_LIBCRYPTSETUP' xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>systemd-cryptsetup</title> <productname>systemd</productname> </refentryinfo> <refmeta> <refentrytitle>systemd-cryptsetup</refentrytitle> <manvolnum>8</manvolnum> </refmeta> <refnamediv> <refname>systemd-cryptsetup</refname> <refname>systemd-cryptsetup@.service</refname> <!-- <refname>system-systemd\x2dcryptsetup.slice</refname> — this causes meson to go haywire because it thinks this is a (windows) path. Let's just not create the alias for this name, and only include it in the synopsis. --> <refpurpose>Full disk decryption logic</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>systemd-cryptsetup</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="plain">attach</arg> <arg choice="plain">VOLUME</arg> <arg choice="plain">SOURCE-DEVICE</arg> <arg choice="opt">KEY-FILE</arg> <arg choice="opt">CONFIG</arg> </cmdsynopsis> <cmdsynopsis> <command>systemd-cryptsetup</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="plain">detach</arg> <arg choice="plain">VOLUME</arg> </cmdsynopsis> <para><filename>systemd-cryptsetup@.service</filename></para> <para><filename>system-systemd\x2dcryptsetup.slice</filename></para> </refsynopsisdiv> <refsect1> <title>Description</title> <para><filename>systemd-cryptsetup</filename> is used to set up (with <command>attach</command>) and tear down (with <command>detach</command>) access to an encrypted block device. It is primarily used via <filename>systemd-cryptsetup@.service</filename> during early boot, but may also be called manually. The positional arguments <parameter>VOLUME</parameter>, <parameter>SOURCE-DEVICE</parameter>, <parameter>KEY-FILE</parameter>, and <parameter>CRYPTTAB-OPTIONS</parameter> have the same meaning as the fields in <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry>. </para> <para><filename>systemd-cryptsetup@.service</filename> is a service responsible for providing access to encrypted block devices. It is instantiated for each device that requires decryption.</para> <para><filename>systemd-cryptsetup@.service</filename> instances are part of the <filename>system-systemd\x2dcryptsetup.slice</filename> slice, which is destroyed only very late in the shutdown procedure. This allows the encrypted devices to remain up until filesystems have been unmounted. </para> <para><filename>systemd-cryptsetup@.service</filename> will ask for hard disk passwords via the <ulink url="https://systemd.io/PASSWORD_AGENTS/">password agent logic</ulink>, in order to query the user for the password using the right mechanism at boot and during runtime.</para> <para>At early boot and when the system manager configuration is reloaded, <filename>/etc/crypttab</filename> is translated into <filename>systemd-cryptsetup@.service</filename> units by <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> <para>In order to unlock a volume a password or binary key is required. <filename>systemd-cryptsetup@.service</filename> tries to acquire a suitable password or binary key via the following mechanisms, tried in order:</para> <orderedlist> <listitem><para>If a key file is explicitly configured (via the third column in <filename>/etc/crypttab</filename>), a key read from it is used. If a PKCS#11 token, FIDO2 token or TPM2 device is configured (using the <varname>pkcs11-uri=</varname>, <varname>fido2-device=</varname>, <varname>tpm2-device=</varname> options) the key is decrypted before use.</para></listitem> <listitem><para>If no key file is configured explicitly this way, a key file is automatically loaded from <filename>/etc/cryptsetup-keys.d/<replaceable>volume</replaceable>.key</filename> and <filename>/run/cryptsetup-keys.d/<replaceable>volume</replaceable>.key</filename>, if present. Here too, if a PKCS#11/FIDO2/TPM2 token/device is configured, any key found this way is decrypted before use.</para></listitem> <listitem><para>If the <varname>try-empty-password</varname> option is specified then unlocking the volume with an empty password is attempted.</para></listitem> <listitem><para>The kernel keyring is then checked for a suitable cached password from previous attempts.</para></listitem> <listitem><para>Finally, the user is queried for a password, possibly multiple times, unless the <varname>headless</varname> option is set.</para></listitem> </orderedlist> <para>If no suitable key may be acquired via any of the mechanisms describes above, volume activation fails.</para> </refsect1> <refsect1> <title>Credentials</title> <para><command>systemd-cryptsetup</command> supports the service credentials logic as implemented by <varname>ImportCredential=</varname>/<varname>LoadCredential=</varname>/<varname>SetCredential=</varname> (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details). The following credentials are used by <literal>systemd-crypsetup@root.service</literal> (generated by <command>systemd-gpt-auto-generator</command>) when passed in:</para> <variablelist class='system-credentials'> <varlistentry> <term><varname>cryptsetup.passphrase</varname></term> <listitem><para>This credential specifies the passphrase of the LUKS volume.</para> <xi:include href="version-info.xml" xpointer="v256"/></listitem> </varlistentry> <varlistentry> <term><varname>cryptsetup.tpm2-pin</varname></term> <listitem><para>This credential specifies the TPM pin.</para> <xi:include href="version-info.xml" xpointer="v256"/></listitem> </varlistentry> <varlistentry> <term><varname>cryptsetup.fido2-pin</varname></term> <listitem><para>This credential specifies the FIDO2 token pin.</para> <xi:include href="version-info.xml" xpointer="v256"/></listitem> </varlistentry> <varlistentry> <term><varname>cryptsetup.pkcs11-pin</varname></term> <listitem><para>This credential specifies the PKCS11 token pin.</para> <xi:include href="version-info.xml" xpointer="v256"/></listitem> </varlistentry> <varlistentry> <term><varname>cryptsetup.luks2-pin</varname></term> <listitem><para>This credential specifies the PIN requested by generic LUKS2 token modules.</para> <xi:include href="version-info.xml" xpointer="v256"/></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>See Also</title> <para><simplelist type="inline"> <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>systemd-cryptenroll</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> <member><citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry></member> <member><ulink url="https://systemd.io/TPM2_PCR_MEASUREMENTS">TPM2 PCR Measurements Made by systemd</ulink></member> </simplelist></para> </refsect1> </refentry>