<?xml version="1.0"?>
<!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
- This file is part of systemd.
-
- Copyright 2012 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ SPDX-License-Identifier: LGPL-2.1+
This is based on crypttab(5) from Fedora's initscripts package, which in
turn is based on Debian's version.
The Red Hat version has been written by Miloslav Trmac <mitr@redhat.com>.
-
-->
<refentry id="crypttab" conditional='HAVE_LIBCRYPTSETUP'>
<refentryinfo>
<title>crypttab</title>
<productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Documentation</contrib>
- <firstname>Miloslav</firstname>
- <surname>Trmac</surname>
- <email>mitr@redhat.com</email>
- </author>
- <author>
- <contrib>Documentation</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
</refentryinfo>
<refmeta>
<para>Empty lines and lines starting with the <literal>#</literal>
character are ignored. Each of the remaining lines describes one
- encrypted block device, fields on the line are delimited by white
- space. The first two fields are mandatory, the remaining two are
+ encrypted block device. Fields are delimited by white space.</para>
+
+ <para>Each line is in the form<programlisting><replaceable>name</replaceable> <replaceable>encrypted-device</replaceable> <replaceable>password</replaceable> <replaceable>options</replaceable></programlisting>
+ The first two fields are mandatory, the remaining two are
optional.</para>
<para>Setting up encrypted block devices using this file supports
field is not present or the password is set to
<literal>none</literal> or <literal>-</literal>, the password has
to be manually entered during system boot. Otherwise, the field is
- interpreted as a absolute path to a file containing the encryption
+ interpreted as an absolute path to a file containing the encryption
password. For swap encryption, <filename>/dev/urandom</filename>
or the hardware device <filename>/dev/hw_random</filename> can be
used as the password file; using <filename>/dev/random</filename>
<variablelist class='fstab-options'>
- <varlistentry>
- <term><option>discard</option></term>
-
- <listitem><para>Allow discard requests to be passed through
- the encrypted block device. This improves performance on SSD
- storage but has security implications.</para></listitem>
- </varlistentry>
-
<varlistentry>
<term><option>cipher=</option></term>
recommended.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>discard</option></term>
+
+ <listitem><para>Allow discard requests to be passed through the encrypted block
+ device. This improves performance on SSD storage but has security implications.
+ </para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>hash=</option></term>
option.</para></listitem>
</varlistentry>
- <varlistentry>
- <term><option>offset=</option></term>
-
- <listitem><para>Start offset in the backend device, in 512-byte sectors.
- This option is only relevant for plain devices.
- </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>skip=</option></term>
-
- <listitem><para>How many 512-byte sectors of the encrypted data to skip
- at the beginning. This is different from the <option>--offset</option>
- option with respect to the sector numbers used in initialization vector
- (IV) calculation. Using <option>--offset</option> will shift the IV
- calculation by the same negative amount. Hence, if <option>--offset n</option> is given,
- sector n will get a sector number of 0 for the IV calculation.
- Using <option>--skip</option> causes sector n to also be the first
- sector of the mapped device, but with its number for IV generation being n.</para>
-
- <para>This option is only relevant for plain devices.</para>
- </listitem>
- </varlistentry>
-
<varlistentry>
<term><option>keyfile-offset=</option></term>
<option>size=</option>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>_netdev</option></term>
+
+ <listitem><para>Marks this cryptsetup device as requiring network. It will be
+ started after the network is available, similarly to
+ <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ units marked with <option>_netdev</option>. The service unit to set up this device
+ will be ordered between <filename>remote-fs-pre.target</filename> and
+ <filename>remote-cryptsetup.target</filename>, instead of
+ <filename>cryptsetup-pre.target</filename> and
+ <filename>cryptsetup.target</filename>.</para>
+
+ <para>Hint: if this device is used for a mount point that is specified in
+ <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ the <option>_netdev</option> option should also be used for the mount
+ point. Otherwise, a dependency loop might be created where the mount point
+ will be pulled in by <filename>local-fs.target</filename>, while the
+ service to configure the network is usually only started <emphasis>after</emphasis>
+ the local file system has been mounted.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>noauto</option></term>
- <listitem><para>This device will not be automatically unlocked
- on boot.</para></listitem>
+ <listitem><para>This device will not be added to <filename>cryptsetup.target</filename>.
+ This means that it will not be automatically unlocked on boot, unless something else pulls
+ it in. In particular, if the device is used for a mount point, it'll be unlocked
+ automatically during boot, unless the mount point itself is also disabled with
+ <option>noauto</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>nofail</option></term>
- <listitem><para>The system will not wait for the device to
- show up and be unlocked at boot, and not fail the boot if it
- does not show up.</para></listitem>
+ <listitem><para>This device will not be a hard dependency of
+ <filename>cryptsetup.target</filename>. It'll be still pulled in and started, but the system
+ will not wait for the device to show up and be unlocked, and boot will not fail if this is
+ unsuccessful. Note that other units that depend on the unlocked device may still fail. In
+ particular, if the device is used for a mount point, the mount point itself is also needs to
+ have <option>noauto</option> option, or the boot will fail if the device is not unlocked
+ successfully.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>offset=</option></term>
+
+ <listitem><para>Start offset in the backend device, in 512-byte sectors. This
+ option is only relevant for plain devices.</para></listitem>
</varlistentry>
<varlistentry>
mode.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>same-cpu-crypt</option></term>
+
+ <listitem><para>Perform encryption using the same cpu that IO was submitted on. The default is to use
+ an unbound workqueue so that encryption work is automatically balanced between available CPUs.</para>
+ <para>This requires kernel 4.0 or newer.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>submit-from-crypt-cpus</option></term>
+
+ <listitem><para>Disable offloading writes to a separate thread after encryption. There are some
+ situations where offloading write bios from the encryption threads to a single thread degrades
+ performance significantly. The default is to offload write bios to the same thread because it benefits
+ CFQ to have writes submitted using the same context.</para>
+ <para>This requires kernel 4.0 or newer.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>skip=</option></term>
+
+ <listitem><para>How many 512-byte sectors of the encrypted data to skip at the
+ beginning. This is different from the <option>offset=</option> option with respect
+ to the sector numbers used in initialization vector (IV) calculation. Using
+ <option>offset=</option> will shift the IV calculation by the same negative
+ amount. Hence, if <option>offset=<replaceable>n</replaceable></option> is given,
+ sector <replaceable>n</replaceable> will get a sector number of 0 for the IV
+ calculation. Using <option>skip=</option> causes sector
+ <replaceable>n</replaceable> to also be the first sector of the mapped device, but
+ with its number for IV generation being <replaceable>n</replaceable>.</para>
+
+ <para>This option is only relevant for plain devices.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>size=</option></term>
option.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>sector-size=</option></term>
+
+ <listitem><para>Specifies the sector size in bytes. See
+ <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ for possible values and the default value of this
+ option.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>swap</option></term>
option implies <option>tcrypt</option>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>tcrypt-veracrypt</option></term>
+
+ <listitem><para>Check for a VeraCrypt volume. VeraCrypt is a fork of
+ TrueCrypt that is mostly compatible, but uses different, stronger key
+ derivation algorithms that cannot be detected without this flag.
+ Enabling this option could substantially slow down unlocking, because
+ VeraCrypt's key derivation takes much longer than TrueCrypt's. This
+ option implies <option>tcrypt</option>.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>timeout=</option></term>
indefinitely (which is the default).</para></listitem>
</varlistentry>
- <varlistentry>
- <term><option>x-systemd.device-timeout=</option></term>
-
- <listitem><para>Specifies how long systemd should wait for a
- device to show up before giving up on the entry. The argument
- is a time in seconds or explicitly specified units of
- <literal>s</literal>,
- <literal>min</literal>,
- <literal>h</literal>,
- <literal>ms</literal>.
- </para></listitem>
- </varlistentry>
-
<varlistentry>
<term><option>tmp</option></term>
typos.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>x-systemd.device-timeout=</option></term>
+
+ <listitem><para>Specifies how long systemd should wait for a device to show up
+ before giving up on the entry. The argument is a time in seconds or explicitly
+ specified units of
+ <literal>s</literal>,
+ <literal>min</literal>,
+ <literal>h</literal>,
+ <literal>ms</literal>.
+ </para></listitem>
+ </varlistentry>
+
</variablelist>
<para>At early boot and when the system manager configuration is
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blobdiff