will also gain an automatic <varname>After=</varname> dependency on
<citerefentry><refentrytitle>systemd-tmpfiles-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
- <listitem><para>Units whose standard output or error output is connected to <option>journal</option>,
- <option>syslog</option> or <option>kmsg</option> (or their combinations with console output, see below)
- automatically acquire dependencies of type <varname>After=</varname> on
+ <listitem><para>Units whose standard output or error output is connected to <option>journal</option> or
+ <option>kmsg</option> (or their combinations with console output, see below) automatically acquire
+ dependencies of type <varname>After=</varname> on
<filename>systemd-journald.socket</filename>.</para></listitem>
<listitem><para>Units using <varname>LogNamespace=</varname> will automatically gain ordering and
<xi:include href="system-only.xml" xpointer="singular"/></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>RootImageOptions=</varname></term>
+
+ <listitem><para>Takes a comma-separated list of mount options that will be used on disk images specified by
+ <varname>RootImage=</varname>. Optionally a partition name can be prefixed, followed by colon, in
+ case the image has multiple partitions, otherwise partition name <literal>root</literal> is implied.
+ Options for multiple partitions can be specified in a single line with space separators. Assigning an empty
+ string removes previous assignments. Duplicated options are ignored. For a list of valid mount options, please
+ refer to <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+
+ <para>Valid partition names follow the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable
+ Partitions Specification</ulink>.</para>
+
+ <table>
+ <title>Accepted partition names</title>
+
+ <tgroup cols='1'>
+ <colspec colname='partition' />
+ <thead>
+ <row>
+ <entry>Partition Name</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>root</entry>
+ </row>
+ <row>
+ <entry>root-secondary</entry>
+ </row>
+ <row>
+ <entry>home</entry>
+ </row>
+ <row>
+ <entry>srv</entry>
+ </row>
+ <row>
+ <entry>esp</entry>
+ </row>
+ <row>
+ <entry>xbootldr</entry>
+ </row>
+ <row>
+ <entry>tmp</entry>
+ </row>
+ <row>
+ <entry>var</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RootHash=</varname></term>
+
+ <listitem><para>Takes a data integrity (dm-verity) root hash specified in hexadecimal, or the path to a file
+ containing a root hash in ASCII hexadecimal format. This option enables data integrity checks using dm-verity,
+ if the used image contains the appropriate integrity data (see above) or if <varname>RootVerity=</varname> is used.
+ The specified hash must match the root hash of integrity data, and is usually at least 256 bits (and hence 64
+ formatted hexadecimal characters) long (in case of SHA256 for example). If this option is not specified, but
+ the image file carries the <literal>user.verity.roothash</literal> extended file attribute (see <citerefentry
+ project='man-pages'><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry>), then the root
+ hash is read from it, also as formatted hexadecimal characters. If the extended file attribute is not found (or
+ is not supported by the underlying file system), but a file with the <filename>.roothash</filename> suffix is
+ found next to the image file, bearing otherwise the same name (except if the image has the
+ <filename>.raw</filename> suffix, in which case the root hash file must not have it in its name), the root hash
+ is read from it and automatically used, also as formatted hexadecimal characters.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RootHashSignature=</varname></term>
+
+ <listitem><para>Takes a PKCS7 formatted binary signature of the <varname>RootHash=</varname> option as a path
+ to a DER encoded signature file or as an ASCII base64 string encoding of the DER encoded signature, prefixed
+ by <literal>base64:</literal>. The dm-verity volume will only be opened if the signature of the root hash
+ signature is valid and created by a public key present in the kernel keyring. If this option is not specified,
+ but a file with the <filename>.roothash.p7s</filename> suffix is found next to the image file, bearing otherwise
+ the same name (except if the image has the <filename>.raw</filename> suffix, in which case the signature file
+ must not have it in its name), the signature is read from it and automatically used.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RootVerity=</varname></term>
+
+ <listitem><para>Takes the path to a data integrity (dm-verity) file. This option enables data integrity checks
+ using dm-verity, if <varname>RootImage=</varname> is used and a root-hash is passed and if the used image itself
+ does not contains the integrity data. The integrity data must be matched by the root hash. If this option is not
+ specified, but a file with the <filename>.verity</filename> suffix is found next to the image file, bearing otherwise
+ the same name (except if the image has the <filename>.raw</filename> suffix, in which case the verity data file must
+ not have it in its name), the verity data is read from it and automatically used.</para>
+
+ <para>This option is supported only for disk images that contain a single file system, without an
+ enveloping partition table. Images that contain a GPT partition table should instead include both
+ root file system and matching Verity data in the same image, implementing the <ulink
+ url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partition Specification</ulink>.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>MountAPIVFS=</varname></term>
<xi:include href="system-only.xml" xpointer="singular"/></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>ProtectProc=</varname></term>
+
+ <listitem><para>Takes one of <literal>noaccess</literal>, <literal>invisible</literal>,
+ <literal>ptraceable</literal> or <literal>default</literal> (which it defaults to). When set, this
+ controls the <literal>hidepid=</literal> mount option of the <literal>procfs</literal> instance for
+ the unit that controls which directories with process metainformation
+ (<filename>/proc/<replaceable>PID</replaceable></filename>) are visible and accessible: when set to
+ <literal>noaccess</literal> the ability to access most of other users' process metadata in
+ <filename>/proc/</filename> is taken away for processes of the service. When set to
+ <literal>invisible</literal> processes owned by other users are hidden from
+ <filename>/proc/</filename>. If <literal>ptraceable</literal> all processes that cannot be
+ <function>ptrace()</function>'ed by a process are hidden to it. If <literal>default</literal> no
+ restrictions on <filename>/proc/</filename> access or visibility are made. For further details see
+ <ulink url="https://www.kernel.org/doc/html/latest/filesystems/proc.html#mount-options">The /proc
+ Filesystem</ulink>. It is generally recommended to run most system services with this option set to
+ <literal>invisible</literal>. This option is implemented via file system namespacing, and thus cannot
+ be used with services that shall be able to install mount points in the host file system
+ hierarchy. It also cannot be used for services that need to access metainformation about other users'
+ processes. This option implies <varname>MountAPIVFS=</varname>.</para>
+
+ <para>If the kernel doesn't support per-mount point <option>hidepid=</option> mount options this
+ setting remains without effect, and the unit's processes will be able to access and see other process
+ as if the option was not used.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ProcSubset=</varname></term>
+
+ <listitem><para>Takes one of <literal>all</literal> (the default) and <literal>pid</literal>. If
+ the latter all files and directories not directly associated with process management and introspection
+ are made invisible in the <filename>/proc/</filename> file system configured for the unit's
+ processes. This controls the <literal>subset=</literal> mount option of the <literal>procfs</literal>
+ instance for the unit. For further details see <ulink
+ url="https://www.kernel.org/doc/html/latest/filesystems/proc.html#mount-options">The /proc
+ Filesystem</ulink>. Note that Linux exposes various kernel APIs via <filename>/proc/</filename>,
+ which are made unavailable with this setting. Since these APIs are used frequently this option is
+ useful only in a few, specific cases, and is not suitable for most non-trivial programs.</para>
+
+ <para>Much like <varname>ProtectProc=</varname> above, this is implemented via file system mount
+ namespacing, and hence the same restrictions apply: it is only available to system services, it
+ disables mount propagation to the host mount table, and it implies
+ <varname>MountAPIVFS=</varname>. Also, like <varname>ProtectProc=</varname> this setting is gracefully
+ disabled if the used kernel does not support the <literal>subset=</literal> mount option of
+ <literal>procfs</literal>.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>BindPaths=</varname></term>
<term><varname>BindReadOnlyPaths=</varname></term>
<xi:include href="system-only.xml" xpointer="singular"/></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>MountImages=</varname></term>
+
+ <listitem><para>This setting is similar to <varname>RootImage=</varname> in that it mounts a file
+ system hierarchy from a block device node or loopback file, but the destination directory can be
+ specified as well as mount options. This option expects a whitespace separated list of mount
+ definitions. Each definition consists of a colon-separated tuple of source path and destination
+ definitions, optionally followed by another colon and a list of mount options.</para>
+
+ <para>Mount options may be defined as a single comma-separated list of options, in which case they
+ will be implicitly applied to the root partition on the image, or a series of colon-separated tuples
+ of partition name and mount options. Valid partition names and mount options are the same as for
+ <varname>RootImageOptions=</varname> setting described above.</para>
+
+ <para>Each mount definition may be prefixed with <literal>-</literal>, in which case it will be
+ ignored when its source path does not exist. The source argument is a path to a block device node or
+ regular file. If source or destination contain a <literal>:</literal>, it needs to be escaped as
+ <literal>\:</literal>. The device node or file system image file needs to follow the same rules as
+ specified for <varname>RootImage=</varname>. Any mounts created with this option are specific to the
+ unit, and are not visible in the host's mount table.</para>
+
+ <para>These settings may be used more than once, each usage appends to the unit's list of mount
+ paths. If the empty string is assigned, the entire list of mount paths defined prior to this is
+ reset.</para>
+
+ <para>Note that the destination directory must exist or systemd must be able to create it. Thus, it
+ is not possible to use those options for mount points nested underneath paths specified in
+ <varname>InaccessiblePaths=</varname>, or under <filename>/home/</filename> and other protected
+ directories if <varname>ProtectHome=yes</varname> is specified.</para>
+
+ <para>When <varname>DevicePolicy=</varname> is set to <literal>closed</literal> or
+ <literal>strict</literal>, or set to <literal>auto</literal> and <varname>DeviceAllow=</varname> is
+ set, then this setting adds <filename>/dev/loop-control</filename> with <constant>rw</constant> mode,
+ <literal>block-loop</literal> and <literal>block-blkext</literal> with <constant>rwm</constant> mode
+ to <varname>DeviceAllow=</varname>. See
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the details about <varname>DevicePolicy=</varname> or <varname>DeviceAllow=</varname>. Also, see
+ <varname>PrivateDevices=</varname> below, as it may change the setting of
+ <varname>DevicePolicy=</varname>.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
+ </varlistentry>
</variablelist>
</refsect1>
files or directories. Moreover <varname>ProtectSystem=strict</varname> and
<varname>ProtectHome=read-only</varname> are implied, thus prohibiting the service to write to
arbitrary file system locations. In order to allow the service to write to certain directories, they
- have to be whitelisted using <varname>ReadWritePaths=</varname>, but care must be taken so that
+ have to be allow-listed using <varname>ReadWritePaths=</varname>, but care must be taken so that
UID/GID recycling doesn't create security issues involving files created by the service. Use
<varname>RuntimeDirectory=</varname> (see below) in order to assign a writable runtime directory to a
service, owned by the dynamic user/group and removed automatically when the unit is terminated. Use
<varlistentry>
<term><varname>CapabilityBoundingSet=</varname></term>
- <listitem><para>Controls which capabilities to include in the capability bounding set for the executed
- process. See <citerefentry
- project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
- details. Takes a whitespace-separated list of capability names, e.g. <constant>CAP_SYS_ADMIN</constant>,
- <constant>CAP_DAC_OVERRIDE</constant>, <constant>CAP_SYS_PTRACE</constant>. Capabilities listed will be
- included in the bounding set, all others are removed. If the list of capabilities is prefixed with
- <literal>~</literal>, all but the listed capabilities will be included, the effect of the assignment
- inverted. Note that this option also affects the respective capabilities in the effective, permitted and
- inheritable capability sets. If this option is not used, the capability bounding set is not modified on process
- execution, hence no limits on the capabilities of the process are enforced. This option may appear more than
- once, in which case the bounding sets are merged by <constant>OR</constant>, or by <constant>AND</constant> if
- the lines are prefixed with <literal>~</literal> (see below). If the empty string is assigned to this option,
- the bounding set is reset to the empty capability set, and all prior settings have no effect. If set to
- <literal>~</literal> (without any further argument), the bounding set is reset to the full set of available
- capabilities, also undoing any previous settings. This does not affect commands prefixed with
- <literal>+</literal>.</para>
+ <listitem><para>Controls which capabilities to include in the capability bounding set for the
+ executed process. See <citerefentry
+ project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details. Takes a whitespace-separated list of capability names,
+ e.g. <constant>CAP_SYS_ADMIN</constant>, <constant>CAP_DAC_OVERRIDE</constant>,
+ <constant>CAP_SYS_PTRACE</constant>. Capabilities listed will be included in the bounding set, all
+ others are removed. If the list of capabilities is prefixed with <literal>~</literal>, all but the
+ listed capabilities will be included, the effect of the assignment inverted. Note that this option
+ also affects the respective capabilities in the effective, permitted and inheritable capability
+ sets. If this option is not used, the capability bounding set is not modified on process execution,
+ hence no limits on the capabilities of the process are enforced. This option may appear more than
+ once, in which case the bounding sets are merged by <constant>OR</constant>, or by
+ <constant>AND</constant> if the lines are prefixed with <literal>~</literal> (see below). If the
+ empty string is assigned to this option, the bounding set is reset to the empty capability set, and
+ all prior settings have no effect. If set to <literal>~</literal> (without any further argument),
+ the bounding set is reset to the full set of available capabilities, also undoing any previous
+ settings. This does not affect commands prefixed with <literal>+</literal>.</para>
+
+ <para>Use
+ <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>capability</command> command to retrieve a list of capabilities defined on the local
+ system.</para>
<para>Example: if a unit has the following,
<programlisting>CapabilityBoundingSet=CAP_A CAP_B
<varlistentry>
<term><varname>AppArmorProfile=</varname></term>
- <listitem><para>Takes a profile name as argument. The process executed by the unit will switch to this profile
- when started. Profiles must already be loaded in the kernel, or the unit will fail. This result in a non
- operation if AppArmor is not enabled. If prefixed by <literal>-</literal>, all errors will be ignored. This
- does not affect commands prefixed with <literal>+</literal>.</para></listitem>
+ <listitem><para>Takes a profile name as argument. The process executed by the unit will switch to
+ this profile when started. Profiles must already be loaded in the kernel, or the unit will fail. If
+ prefixed by <literal>-</literal>, all errors will be ignored. This setting has no effect if AppArmor
+ is not enabled. This setting not affect commands prefixed with <literal>+</literal>.</para>
+ </listitem>
</varlistentry>
<varlistentry>
kernel default of <literal><constant>private-anonymous</constant>
<constant>shared-anonymous</constant> <constant>elf-headers</constant>
<constant>private-huge</constant></literal>). See
- <citerefentry><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for the
- meaning of the mapping types. When specified multiple times, all specified masks are ORed. When not
- set, or if the empty value is assigned, the inherited value is not changed.</para>
+ <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the meaning of the mapping types. When specified multiple times, all specified masks are
+ ORed. When not set, or if the empty value is assigned, the inherited value is not changed.</para>
<example>
<title>Add DAX pages to the dump filter</title>
in <varname>NUMAMask=</varname>. For more details on each policy please see,
<citerefentry><refentrytitle>set_mempolicy</refentrytitle><manvolnum>2</manvolnum></citerefentry>. For overall
overview of NUMA support in Linux see,
- <citerefentry><refentrytitle>numa</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>numa</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para></listitem>
</varlistentry>
<varname>RootDirectory=</varname> or <varname>RootImage=</varname> these paths always reside on the host and
are mounted from there into the unit's file system namespace.</para>
- <para>If <varname>DynamicUser=</varname> is used in conjunction with <varname>StateDirectory=</varname>,
- <varname>CacheDirectory=</varname> and <varname>LogsDirectory=</varname> is slightly altered: the directories
- are created below <filename>/var/lib/private</filename>, <filename>/var/cache/private</filename> and
+ <para>If <varname>DynamicUser=</varname> is used in conjunction with
+ <varname>StateDirectory=</varname>, the logic for <varname>CacheDirectory=</varname> and
+ <varname>LogsDirectory=</varname> is slightly altered: the directories are created below
+ <filename>/var/lib/private</filename>, <filename>/var/cache/private</filename> and
<filename>/var/log/private</filename>, respectively, which are host directories made inaccessible to
- unprivileged users, which ensures that access to these directories cannot be gained through dynamic user ID
- recycling. Symbolic links are created to hide this difference in behaviour. Both from perspective of the host
- and from inside the unit, the relevant directories hence always appear directly below
- <filename>/var/lib</filename>, <filename>/var/cache</filename> and <filename>/var/log</filename>.</para>
+ unprivileged users, which ensures that access to these directories cannot be gained through dynamic
+ user ID recycling. Symbolic links are created to hide this difference in behaviour. Both from
+ perspective of the host and from inside the unit, the relevant directories hence always appear
+ directly below <filename>/var/lib</filename>, <filename>/var/cache</filename> and
+ <filename>/var/log</filename>.</para>
<para>Use <varname>RuntimeDirectory=</varname> to manage one or more runtime directories for the unit and bind
their lifetime to the daemon runtime. This is particularly useful for unprivileged daemons that cannot create
clean …</command>, see
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> for
details. Takes the usual time values and defaults to <constant>infinity</constant>, i.e. by default
- no time-out is applied. If a time-out is configured the clean operation will be aborted forcibly when
- the time-out is reached, potentially leaving resources on disk.</para></listitem>
+ no timeout is applied. If a timeout is configured the clean operation will be aborted forcibly when
+ the timeout is reached, potentially leaving resources on disk.</para></listitem>
</varlistentry>
<varlistentry>
contain symlinks, they are resolved relative to the root directory set with
<varname>RootDirectory=</varname>/<varname>RootImage=</varname>.</para>
- <para>Paths listed in <varname>ReadWritePaths=</varname> are accessible from within the namespace with the same
- access modes as from outside of it. Paths listed in <varname>ReadOnlyPaths=</varname> are accessible for
- reading only, writing will be refused even if the usual file access controls would permit this. Nest
- <varname>ReadWritePaths=</varname> inside of <varname>ReadOnlyPaths=</varname> in order to provide writable
- subdirectories within read-only directories. Use <varname>ReadWritePaths=</varname> in order to whitelist
- specific paths for write access if <varname>ProtectSystem=strict</varname> is used.</para>
+ <para>Paths listed in <varname>ReadWritePaths=</varname> are accessible from within the namespace
+ with the same access modes as from outside of it. Paths listed in <varname>ReadOnlyPaths=</varname>
+ are accessible for reading only, writing will be refused even if the usual file access controls would
+ permit this. Nest <varname>ReadWritePaths=</varname> inside of <varname>ReadOnlyPaths=</varname> in
+ order to provide writable subdirectories within read-only directories. Use
+ <varname>ReadWritePaths=</varname> in order to allow-list specific paths for write access if
+ <varname>ProtectSystem=strict</varname> is used.</para>
<para>Paths listed in <varname>InaccessiblePaths=</varname> will be made inaccessible for processes inside
the namespace along with everything below them in the file system hierarchy. This may be more restrictive than
<term><varname>PrivateTmp=</varname></term>
<listitem><para>Takes a boolean argument. If true, sets up a new file system namespace for the executed
- processes and mounts private <filename>/tmp</filename> and <filename>/var/tmp</filename> directories inside it
- that is not shared by processes outside of the namespace. This is useful to secure access to temporary files of
+ processes and mounts private <filename>/tmp/</filename> and <filename>/var/tmp/</filename> directories inside it
+ that are not shared by processes outside of the namespace. This is useful to secure access to temporary files of
the process, but makes sharing between processes via <filename>/tmp</filename> or <filename>/var/tmp</filename>
impossible. If this is enabled, all temporary files created by a service in these directories will be removed
after the service is stopped. Defaults to false. It is possible to run two or more units within the same
this option removes <constant>CAP_SYS_TIME</constant> and <constant>CAP_WAKE_ALARM</constant> from the
capability bounding set for this unit, installs a system call filter to block calls that can set the
clock, and <varname>DeviceAllow=char-rtc r</varname> is implied. This ensures <filename>/dev/rtc0</filename>,
- <filename>/dev/rtc1</filename>, etc are made read only to the service. See
+ <filename>/dev/rtc1</filename>, etc. are made read-only to the service. See
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for the details about <varname>DeviceAllow=</varname>.</para>
<varlistentry>
<term><varname>RestrictAddressFamilies=</varname></term>
- <listitem><para>Restricts the set of socket address families accessible to the processes of this unit. Takes a
- space-separated list of address family names to whitelist, such as <constant>AF_UNIX</constant>,
- <constant>AF_INET</constant> or <constant>AF_INET6</constant>. When prefixed with <constant>~</constant> the
- listed address families will be applied as blacklist, otherwise as whitelist. Note that this restricts access
- to the <citerefentry
- project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry> system call
- only. Sockets passed into the process by other means (for example, by using socket activation with socket
- units, see <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
- are unaffected. Also, sockets created with <function>socketpair()</function> (which creates connected AF_UNIX
- sockets only) are unaffected. Note that this option has no effect on 32-bit x86, s390, s390x, mips, mips-le,
- ppc, ppc-le, pcc64, ppc64-le and is ignored (but works correctly on other ABIs, including x86-64). Note that on
- systems supporting multiple ABIs (such as x86/x86-64) it is recommended to turn off alternative ABIs for
- services, so that they cannot be used to circumvent the restrictions of this option. Specifically, it is
- recommended to combine this option with <varname>SystemCallArchitectures=native</varname> or similar. If
- running in user mode, or in system mode, but without the <constant>CAP_SYS_ADMIN</constant> capability
- (e.g. setting <varname>User=nobody</varname>), <varname>NoNewPrivileges=yes</varname> is implied. By default,
- no restrictions apply, all address families are accessible to processes. If assigned the empty string, any
- previous address family restriction changes are undone. This setting does not affect commands prefixed with
- <literal>+</literal>.</para>
+ <listitem><para>Restricts the set of socket address families accessible to the processes of this
+ unit. Takes a space-separated list of address family names to allow-list, such as
+ <constant>AF_UNIX</constant>, <constant>AF_INET</constant> or <constant>AF_INET6</constant>. When
+ prefixed with <constant>~</constant> the listed address families will be applied as deny list,
+ otherwise as allow list. Note that this restricts access to the <citerefentry
+ project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ system call only. Sockets passed into the process by other means (for example, by using socket
+ activation with socket units, see
+ <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
+ are unaffected. Also, sockets created with <function>socketpair()</function> (which creates connected
+ AF_UNIX sockets only) are unaffected. Note that this option has no effect on 32-bit x86, s390, s390x,
+ mips, mips-le, ppc, ppc-le, ppc64, ppc64-le and is ignored (but works correctly on other ABIs,
+ including x86-64). Note that on systems supporting multiple ABIs (such as x86/x86-64) it is
+ recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the
+ restrictions of this option. Specifically, it is recommended to combine this option with
+ <varname>SystemCallArchitectures=native</varname> or similar. If running in user mode, or in system
+ mode, but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting
+ <varname>User=nobody</varname>), <varname>NoNewPrivileges=yes</varname> is implied. By default, no
+ restrictions apply, all address families are accessible to processes. If assigned the empty string,
+ any previous address family restriction changes are undone. This setting does not affect commands
+ prefixed with <literal>+</literal>.</para>
<para>Use this option to limit exposure of processes to remote access, in particular via exotic and sensitive
network protocols, such as <constant>AF_PACKET</constant>. Note that in most cases, the local
- <constant>AF_UNIX</constant> address family should be included in the configured whitelist as it is frequently
+ <constant>AF_UNIX</constant> address family should be included in the configured allow list as it is frequently
used for local communication, including for
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
logging.</para></listitem>
any combination of: <constant>cgroup</constant>, <constant>ipc</constant>, <constant>net</constant>,
<constant>mnt</constant>, <constant>pid</constant>, <constant>user</constant> and <constant>uts</constant>. Any
namespace type listed is made accessible to the unit's processes, access to namespace types not listed is
- prohibited (whitelisting). By prepending the list with a single tilde character (<literal>~</literal>) the
+ prohibited (allow-listing). By prepending the list with a single tilde character (<literal>~</literal>) the
effect may be inverted: only the listed namespace types will be made inaccessible, all unlisted ones are
- permitted (blacklisting). If the empty string is assigned, the default namespace restrictions are applied,
+ permitted (deny-listing). If the empty string is assigned, the default namespace restrictions are applied,
which is equivalent to false. This option may appear more than once, in which case the namespace types are
merged by <constant>OR</constant>, or by <constant>AND</constant> if the lines are prefixed with
<literal>~</literal> (see examples below). Internally, this setting limits access to the
<option>shared</option> mount propagation is used, but — as mentioned — as <option>slave</option> is applied
first, propagation from the unit's processes to the host is still turned off.</para>
- <para>It is not recommended to to use <option>private</option> mount propagation for units, as this means
+ <para>It is not recommended to use <option>private</option> mount propagation for units, as this means
temporary mounts (such as removable media) of the host will stay mounted and thus indefinitely busy in forked
off processes, as unmount propagation events won't be received by the file system namespace of the unit.</para>
<listitem><para>Takes a space-separated list of system call names. If this setting is used, all
system calls executed by the unit processes except for the listed ones will result in immediate
- process termination with the <constant>SIGSYS</constant> signal (whitelisting). (See
+ process termination with the <constant>SIGSYS</constant> signal (allow-listing). (See
<varname>SystemCallErrorNumber=</varname> below for changing the default action). If the first
character of the list is <literal>~</literal>, the effect is inverted: only the listed system calls
- will result in immediate process termination (blacklisting). Blacklisted system calls and system call
+ will result in immediate process termination (deny-listing). Deny-listed system calls and system call
groups may optionally be suffixed with a colon (<literal>:</literal>) and <literal>errno</literal>
error number (between 0 and 4095) or errno name such as <constant>EPERM</constant>,
<constant>EACCES</constant> or <constant>EUCLEAN</constant> (see <citerefentry
project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> for a
- full list). This value will be returned when a blacklisted system call is triggered, instead of
+ full list). This value will be returned when a deny-listed system call is triggered, instead of
terminating the processes immediately. This value takes precedence over the one given in
<varname>SystemCallErrorNumber=</varname>, see below. If running in user mode, or in system mode,
but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting
for enforcing a minimal sandboxing environment. Note that the <function>execve</function>,
<function>exit</function>, <function>exit_group</function>, <function>getrlimit</function>,
<function>rt_sigreturn</function>, <function>sigreturn</function> system calls and the system calls
- for querying time and sleeping are implicitly whitelisted and do not need to be listed
+ for querying time and sleeping are implicitly allow-listed and do not need to be listed
explicitly. This option may be specified more than once, in which case the filter masks are
merged. If the empty string is assigned, the filter is reset, all prior assignments will have no
effect. This does not affect commands prefixed with <literal>+</literal>.</para>
might be necessary to temporarily disable system call filters in order to simplify debugging of such
failures.</para>
- <para>If you specify both types of this option (i.e. whitelisting and blacklisting), the first encountered
- will take precedence and will dictate the default action (termination or approval of a system call). Then the
- next occurrences of this option will add or delete the listed system calls from the set of the filtered system
- calls, depending of its type and the default action. (For example, if you have started with a whitelisting of
- <function>read</function> and <function>write</function>, and right after it add a blacklisting of
- <function>write</function>, then <function>write</function> will be removed from the set.)</para>
+ <para>If you specify both types of this option (i.e. allow-listing and deny-listing), the first
+ encountered will take precedence and will dictate the default action (termination or approval of a
+ system call). Then the next occurrences of this option will add or delete the listed system calls
+ from the set of the filtered system calls, depending of its type and the default action. (For
+ example, if you have started with an allow list rule for <function>read</function> and
+ <function>write</function>, and right after it add a deny list rule for <function>write</function>,
+ then <function>write</function> will be removed from the set.)</para>
<para>As the number of possible system calls is large, predefined sets of system calls are provided. A set
starts with <literal>@</literal> character, followed by name of the set.
</row>
<row>
<entry>@file-system</entry>
- <entry>File system operations: opening, creating files and directories for read and write, renaming and removing them, reading file properties, or creating hard and symbolic links.</entry>
+ <entry>File system operations: opening, creating files and directories for read and write, renaming and removing them, reading file properties, or creating hard and symbolic links</entry>
</row>
<row>
<entry>@io-event</entry>
</row>
<row>
<entry>@memlock</entry>
- <entry>Locking of memory into RAM (<citerefentry project='man-pages'><refentrytitle>mlock</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>mlockall</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
+ <entry>Locking of memory in RAM (<citerefentry project='man-pages'><refentrytitle>mlock</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>mlockall</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
</row>
<row>
<entry>@module</entry>
</row>
<row>
<entry>@process</entry>
- <entry>Process control, execution, namespaceing operations (<citerefentry project='man-pages'><refentrytitle>clone</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>, …</entry>
+ <entry>Process control, execution, namespaceing operations (<citerefentry project='man-pages'><refentrytitle>clone</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>, …)</entry>
</row>
<row>
<entry>@raw-io</entry>
</row>
<row>
<entry>@sync</entry>
- <entry>Synchronizing files and memory to disk: (<citerefentry project='man-pages'><refentrytitle>fsync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>msync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry>
+ <entry>Synchronizing files and memory to disk (<citerefentry project='man-pages'><refentrytitle>fsync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>msync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry>
</row>
<row>
<entry>@system-service</entry>
- <entry>A reasonable set of system calls used by common system services, excluding any special purpose calls. This is the recommended starting point for whitelisting system calls for system services, as it contains what is typically needed by system services, but excludes overly specific interfaces. For example, the following APIs are excluded: <literal>@clock</literal>, <literal>@mount</literal>, <literal>@swap</literal>, <literal>@reboot</literal>.</entry>
+ <entry>A reasonable set of system calls used by common system services, excluding any special purpose calls. This is the recommended starting point for allow-listing system calls for system services, as it contains what is typically needed by system services, but excludes overly specific interfaces. For example, the following APIs are excluded: <literal>@clock</literal>, <literal>@mount</literal>, <literal>@swap</literal>, <literal>@reboot</literal>.</entry>
</row>
<row>
<entry>@timer</entry>
<entry>System calls for scheduling operations by time (<citerefentry project='man-pages'><refentrytitle>alarm</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>timer_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry>
</row>
+ <row>
+ <entry>@known</entry>
+ <entry>All system calls defined by the kernel. This list is defined statically in systemd based on a kernel version that was available when this systmed version was released. It will become progressively more out-of-date as the kernel is updated.</entry>
+ </row>
</tbody>
</tgroup>
</table>
<command>systemd-analyze syscall-filter</command> to list the actual list of system calls in each
filter.</para>
- <para>Generally, whitelisting system calls (rather than blacklisting) is the safer mode of operation. It is
- recommended to enforce system call whitelists for all long-running system services. Specifically, the
- following lines are a relatively safe basic choice for the majority of system services:</para>
+ <para>Generally, allow-listing system calls (rather than deny-listing) is the safer mode of
+ operation. It is recommended to enforce system call allow lists for all long-running system
+ services. Specifically, the following lines are a relatively safe basic choice for the majority of
+ system services:</para>
<programlisting>[Service]
SystemCallFilter=@system-service
call may be used to execute operations similar to what can be done with the older
<function>kill()</function> system call, hence blocking the latter without the former only provides
weak protection. Since new system calls are added regularly to the kernel as development progresses,
- keeping system call blacklists comprehensive requires constant work. It is thus recommended to use
- whitelisting instead, which offers the benefit that new system calls are by default implicitly
- blocked until the whitelist is updated.</para>
+ keeping system call deny lists comprehensive requires constant work. It is thus recommended to use
+ allow-listing instead, which offers the benefit that new system calls are by default implicitly
+ blocked until the allow list is updated.</para>
<para>Also note that a number of system calls are required to be accessible for the dynamic linker to
work. The dynamic linker is required for running most regular programs (specifically: all dynamic ELF
manager is compiled for). If running in user mode, or in system mode, but without the
<constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=nobody</varname>),
<varname>NoNewPrivileges=yes</varname> is implied. By default, this option is set to the empty list, i.e. no
- system call architecture filtering is applied.</para>
+ filtering is applied.</para>
<para>If this setting is used, processes of this unit will only be permitted to call native system calls, and
system calls of the specified architectures. For the purposes of this option, the x32 architecture is treated
project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details
about environment variables.</para>
- <para>Note that environment variables are not suitable for passing secrets (such as passwords, key material, …)
- to service processes. Environment variables set for a unit are exposed to unprivileged clients via D-Bus IPC,
- and generally not understood as being data that requires protection. Moreover, environment variables are
- propagated down the process tree, including across security boundaries (such as setuid/setgid executables), and
- hence might leak to processes that should not have access to the secret data.</para></listitem>
+ <para>Note that environment variables are not suitable for passing secrets (such as passwords, key
+ material, …) to service processes. Environment variables set for a unit are exposed to unprivileged
+ clients via D-Bus IPC, and generally not understood as being data that requires protection. Moreover,
+ environment variables are propagated down the process tree, including across security boundaries
+ (such as setuid/setgid executables), and hence might leak to processes that should not have access to
+ the secret data. Use <varname>LoadCredential=</varname> (see below) to pass data to unit processes
+ securely.</para></listitem>
</varlistentry>
<varlistentry>
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more
details about named file descriptors and their ordering.</para>
- <para>This setting defaults to <option>null</option>.</para>
-
- <para>Note that services which specify <option>DefaultDependencies=no</option> and use
- <varname>StandardInput=</varname> or <varname>StandardOutput=</varname> with
- <option>tty</option>/<option>tty-force</option>/<option>tty-fail</option>, should specify
- <option>After=systemd-vconsole-setup.service</option>, to make sure that the tty initialization is
- finished before they start.</para></listitem>
+ <para>This setting defaults to <option>null</option>.</para></listitem>
</varlistentry>
<varlistentry>
<constant>AF_UNIX</constant> socket in the file system, as in that case only a
single stream connection is created for both input and output.</para>
- <para><option>append:<replaceable>path</replaceable></option> is similar to <option>file:<replaceable>path
- </replaceable></option> above, but it opens the file in append mode.</para>
+ <para><option>append:<replaceable>path</replaceable></option> is similar to
+ <option>file:<replaceable>path</replaceable></option> above, but it opens the file in append mode.
+ </para>
<para><option>socket</option> connects standard output to a socket acquired via socket activation. The
semantics are similar to the same option of <varname>StandardInput=</varname>, see above.</para>
so that they are automatically established prior to the unit starting up. Note that when this option
is used log output of this service does not appear in the regular
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- output, unless the <option>--namespace=</option> option is used.</para></listitem>
+ output, unless the <option>--namespace=</option> option is used.</para>
+
+ <xi:include href="system-only.xml" xpointer="singular"/></listitem>
</varlistentry>
<varlistentry>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Credentials</title>
+
+ <variablelist class='unit-directives'>
+
+ <varlistentry>
+ <term><varname>LoadCredential=</varname><replaceable>ID</replaceable>:<replaceable>PATH</replaceable></term>
+
+ <listitem><para>Pass a credential to the unit. Credentials are limited-size binary or textual objects
+ that may be passed to unit processes. They are primarily used for passing cryptographic keys (both
+ public and private) or certificates, user account information or identity information from host to
+ services. The data is accessible from the unit's processes via the file system, at a read-only
+ location that (if possible and permitted) is backed by non-swappable memory. The data is only
+ accessible to the user associated with the unit, via the
+ <varname>User=</varname>/<varname>DynamicUser=</varname> settings (as well as the superuser). When
+ available, the location of credentials is exported as the <varname>$CREDENTIALS_DIRECTORY</varname>
+ environment variable to the unit's processes.</para>
+
+ <para>The <varname>LoadCredential=</varname> setting takes a textual ID to use as name for a
+ credential plus a file system path. The ID must be a short ASCII string suitable as filename in the
+ filesystem, and may be chosen freely by the user. If the specified path is absolute it is opened as
+ regular file and the credential data is read from it. If the absolute path refers to an
+ <constant>AF_UNIX</constant> stream socket in the file system a connection is made to it and the
+ credential data read from the connection, providing an easy IPC integration point for dynamically
+ providing credentials from other services. If the specified path is not absolute and itself qualifies
+ as valid credential identifier it is understood to refer to a credential that the service manager
+ itself received via the <varname>$CREDENTIALS_DIRECTORY</varname> environment variable, which may be
+ used to propagate credentials from an invoking environment (e.g. a container manager that invoked the
+ service manager) into a service. The contents of the file/socket may be arbitrary binary or textual
+ data, including newline characters and NUL bytes. This option may be used multiple times, each time
+ defining an additional credential to pass to the unit.</para>
+
+ <para>The credential files/IPC sockets must be accessible to the service manager, but don't have to
+ be directly accessible to the unit's processes: the credential data is read and copied into separate,
+ read-only copies for the unit that are accessible to appropriately privileged processes. This is
+ particularly useful in combination with <varname>DynamicUser=</varname> as this way privileged data
+ can be made available to processes running under a dynamic UID (i.e. not a previously known one)
+ without having to open up access to all users.</para>
+
+ <para>In order to reference the path a credential may be read from within a
+ <varname>ExecStart=</varname> command line use <literal>${CREDENTIALS_DIRECTORY}/mycred</literal>,
+ e.g. <literal>ExecStart=cat ${CREDENTIALS_DIRECTORY}/mycred</literal>.</para>
+
+ <para>Currently, an accumulated credential size limit of 1M bytes per unit is
+ enforced.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SetCredential=</varname><replaceable>ID</replaceable>:<replaceable>VALUE</replaceable></term>
+
+ <listitem><para>The <varname>SetCredential=</varname> setting is similar to
+ <varname>LoadCredential=</varname> but accepts a literal value to use as data for the credential,
+ instead of a file system path to read the data from. Do not use this option for data that is supposed
+ to be secret, as it is accessible to unprivileged processes via IPC. It's only safe to use this for
+ user IDs, public key material and similar non-sensitive data. For everything else use
+ <varname>LoadCredential=</varname>. In order to embed binary data into the credential data use
+ C-style escaping (i.e. <literal>\n</literal> to embed a newline, or <literal>\x00</literal> to embed
+ a NUL byte).</para>
+
+ <para>If a credential of the same ID is listed in both <varname>LoadCredential=</varname> and
+ <varname>SetCredential=</varname>, the latter will act as default if the former cannot be
+ retrieved. In this case not being able to retrieve the credential from the path specified in
+ <varname>LoadCredential=</varname> is not considered fatal.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
<refsect1>
<title>System V Compatibility</title>
<variablelist class='unit-directives'>
<varname>UnsetEnvironment=</varname> are removed again from the compiled environment variable list, immediately
before it is passed to the executed process.</para>
- <para>The following select environment variables are set or propagated by the service manager for each invoked
+ <para>The following environment variables are set or propagated by the service manager for each invoked
process:</para>
<variablelist class='environment-variables'>
<term><varname>$LOGS_DIRECTORY</varname></term>
<term><varname>$CONFIGURATION_DIRECTORY</varname></term>
- <listitem><para>Contains and absolute paths to the directories defined with
+ <listitem><para>Absolute paths to the directories defined with
<varname>RuntimeDirectory=</varname>, <varname>StateDirectory=</varname>,
<varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname>, and
<varname>ConfigurationDirectory=</varname> when those settings are used.</para>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>$CREDENTIALS_DIRECTORY</varname></term>
+
+ <listitem><para>An absolute path to the per-unit directory with credentials configured via
+ <varname>LoadCredential=</varname>/<varname>SetCredential=</varname>. The directory is marked
+ read-only and is placed in unswappable memory (if supported and permitted), and is only accessible to
+ the UID associated with the unit via <varname>User=</varname> or <varname>DynamicUser=</varname> (and
+ the superuser).</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>$MAINPID</varname></term>
</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>$LOG_NAMESPACE</varname></term>
+
+ <listitem><para>If the <varname>LogNamespace=</varname> service setting is used, contains name of the
+ selected logging namespace.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>$JOURNAL_STREAM</varname></term>
<row>
<entry>242</entry>
<entry><constant>EXIT_NUMA_POLICY</constant></entry>
- <entry>Failed to set up unit's NUMA memory policy. See <varname>NUMAPolicy=</varname> and <varname>NUMAMask=</varname>above.</entry>
+ <entry>Failed to set up unit's NUMA memory policy. See <varname>NUMAPolicy=</varname> and <varname>NUMAMask=</varname> above.</entry>
+ </row>
+ <row>
+ <entry>243</entry>
+ <entry><constant>EXIT_CREDENTIALS</constant></entry>
+ <entry>Failed to set up unit's credentials. See <varname>LoadCredential=</varname> and <varname>SetCredential=</varname> above.</entry>
</row>
-
</tbody>
</tgroup>
</table>
projects / thirdparty / systemd.git / blobdiff