<title>Description</title>
<para>Unit configuration files for services, sockets,
- mount points and swap devices share a subset of
+ mount points, and swap devices share a subset of
configuration options which define the execution
environment of spawned processes.</para>
configuration options are configured in the [Service],
[Socket], [Mount], or [Swap] sections, depending on the unit
type.</para>
-
- <para>Processes started by the system systemd instance
- are executed in a clean environment in which only the
- <varname>$PATH</varname> and <varname>$LANG</varname>
- variables are set by default. In order to add
- additional variables, see the
- <varname>Environment=</varname> and
- <varname>EnvironmentFile=</varname> options below. To
- specify variables globally, see
- <varname>DefaultEnvironment=</varname> in
- <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- or the kernel option
- <varname>systemd.setenv=</varname> in
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Processes
- started by the user systemd instances inherit all
- environment variables from the user systemd instance,
- and have <varname>$HOME</varname>,
- <varname>$USER</varname>,
- <varname>$XDG_RUNTIME_DIR</varname> defined, among
- others. In addition, <varname>$MANAGERPID</varname>
- contains the PID of the user systemd instance.</para>
</refsect1>
<refsect1>
<listitem><para>Takes an absolute
directory path. Sets the working
directory for executed processes. If
- not set defaults to the root directory
+ not set, defaults to the root directory
when systemd is running as a system
instance and the respective user's
home directory if run as
directory path. Sets the root
directory for executed processes, with
the
- <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- system call. If this is used it must
+ <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ system call. If this is used, it must
be ensured that the process and all
its auxiliary files are available in
the <function>chroot()</function>
<term><varname>CPUSchedulingResetOnFork=</varname></term>
<listitem><para>Takes a boolean
- argument. If true elevated CPU
+ argument. If true, elevated CPU
scheduling priorities and policies
will be reset when the executed
processes fork, and can hence not leak
<listitem><para>Controls the CPU
affinity of the executed
processes. Takes a space-separated
- list of CPU indexes. This option may
+ list of CPU indices. This option may
be specified more than once in which
case the specificed CPU affinity masks
are merged. If the empty string is
- assigned the mask is reset, all
+ assigned, the mask is reset, all
assignments prior to this will have no
effect. See
<citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
option may be specified more than once
in which case all listed variables
will be set. If the same variable is
- set twice the later setting will
+ set twice, the later setting will
override the earlier setting. If the
empty string is assigned to this
- option the list of environment
+ option, the list of environment
variables is reset, all prior
assignments have no effect.
Variable expansion is not performed
inside the strings, however, specifier
- expansion is possible. $ character has
+ expansion is possible. The $ character has
no special meaning.
If you need to assign a value containing spaces
to a variable, use double quotes (")
for the assignment.</para>
<para>Example:
- <programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"</programlisting>
+ <programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</programlisting>
gives three variables <literal>VAR1</literal>,
- <literal>VAR2</literal>, <literal>VAR3</literal>.
+ <literal>VAR2</literal>, <literal>VAR3</literal>
+ with the values <literal>word1 word2</literal>,
+ <literal>word3</literal>, <literal>$word 5 6</literal>.
</para>
<para>
See
- <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details about environment variables.</para></listitem>
</varlistentry>
<varlistentry>
specified more than once in which case
all specified files are read. If the
empty string is assigned to this
- option the list of file to read is
+ option, the list of file to read is
reset, all prior assignments have no
effect.</para>
<para>The files listed with this
directive will be read shortly before
- the process is executed. Settings from
- these files override settings made
- with
+ the process is executed (more
+ specifically, after all
+ processes from a previous unit state
+ terminated. This means you can
+ generate these files in one unit
+ state, and read it with this option in
+ the next). Settings from these files
+ override settings made with
<varname>Environment=</varname>. If
the same variable is set twice from
- these files the files will be read in
+ these files, the files will be read in
the order they are specified and the
later setting will override the
earlier setting.</para></listitem>
<option>tty-force</option>,
<option>tty-fail</option> or
<option>socket</option>. If
- <option>null</option> is selected
+ <option>null</option> is selected,
standard input will be connected to
<filename>/dev/null</filename>,
i.e. all read attempts by the process
will result in immediate EOF. If
- <option>tty</option> is selected
+ <option>tty</option> is selected,
standard input is connected to a TTY
(as configured by
<varname>TTYPath=</varname>, see
below) and the executed process
becomes the controlling process of the
terminal. If the terminal is already
- being controlled by another process the
+ being controlled by another process, the
executed process waits until the current
controlling process releases the
terminal.
file (see
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) specifies a single socket
- only. If this option is set standard
+ only. If this option is set, standard
input will be connected to the socket
the service was activated from, which
is primarily useful for compatibility
<option>kmsg+console</option>,
<option>journal+console</option> or
<option>socket</option>. If set to
- <option>inherit</option> the file
+ <option>inherit</option>, the file
descriptor of standard input is
duplicated for standard output. If set
- to <option>null</option> standard
+ to <option>null</option>, standard
output will be connected to
<filename>/dev/null</filename>,
i.e. everything written to it will be
- lost. If set to <option>tty</option>
+ lost. If set to <option>tty</option>,
standard output will be connected to a
tty (as configured via
<varname>TTYPath=</varname>, see
below). If the TTY is used for output
- only the executed process will not
+ only, the executed process will not
become the controlling process of the
terminal, and will not fail or wait
for other processes to release the
terminal. <option>syslog</option>
connects standard output to the
- <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
system syslog
service. <option>kmsg</option>
connects it with the kernel log buffer
which is accessible via
- <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>journal</option>
+ <citerefentry project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>journal</option>
connects it with the journal which is
accessible via
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
<varlistentry>
<term><varname>StandardError=</varname></term>
<listitem><para>Controls where file
- descriptor 2 (STDERR) of the executed
- processes is connected to. The
- available options are identical to
+ descriptor 2 (STDERR) of the
+ executed processes is connected to.
+ The available options are identical to
those of
<varname>StandardOutput=</varname>,
with one exception: if set to
<varlistentry>
<term><varname>TTYPath=</varname></term>
<listitem><para>Sets the terminal
- device node to use if standard input,
- output or stderr are connected to a
+ device node to use if standard input, output,
+ or error are connected to a
TTY (see above). Defaults to
<filename>/dev/console</filename>.</para></listitem>
</varlistentry>
<listitem><para>If the terminal
device specified with
<varname>TTYPath=</varname> is a
- virtual console terminal try to
+ virtual console terminal, try to
deallocate the TTY before and after
execution. This ensures that the
screen and scrollback buffer is
<term><varname>SyslogIdentifier=</varname></term>
<listitem><para>Sets the process name
to prefix log lines sent to syslog or
- the kernel log buffer with. If not set
+ the kernel log buffer with. If not set,
defaults to the process name of the
executed process. This option is only
useful when
<option>local5</option>,
<option>local6</option> or
<option>local7</option>. See
- <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for details. This option is only
useful when
<varname>StandardOutput=</varname> or
<option>notice</option>,
<option>info</option>,
<option>debug</option>. See
- <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for details. This option is only
useful when
<varname>StandardOutput=</varname> or
<varlistentry>
<term><varname>PAMName=</varname></term>
<listitem><para>Sets the PAM service
- name to set up a session as. If set
+ name to set up a session as. If set,
the executed process will be
registered as a PAM session under the
specified service name. This is only
useful in conjunction with the
<varname>User=</varname> setting. If
- not set no PAM session will be opened
+ not set, no PAM session will be opened
for the executed processes. See
- <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
- <varlistentry>
- <term><varname>TCPWrapName=</varname></term>
- <listitem><para>If this is a
- socket-activated service this sets the
- tcpwrap service name to check the
- permission for the current connection
- with. This is only useful in
- conjunction with socket-activated
- services, and stream sockets (TCP) in
- particular. It has no effect on other
- socket types (e.g. datagram/UDP) and
- on processes unrelated to socket-based
- activation. If the tcpwrap
- verification fails daemon start-up
- will fail and the connection is
- terminated. See
- <citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for details. Note that this option may
- be used to do access control checks
- only. Shell commands and commands
- described in
- <citerefentry><refentrytitle>hosts_options</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- are not supported.</para></listitem>
- </varlistentry>
-
<varlistentry>
<term><varname>CapabilityBoundingSet=</varname></term>
capabilities to include in the
capability bounding set for the
executed process. See
- <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details. Takes a whitespace-separated
list of capability names as read by
<citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
Capabilities listed will be included
in the bounding set, all others are
removed. If the list of capabilities
- is prefixed with <literal>~</literal>
+ is prefixed with <literal>~</literal>,
all but the listed capabilities will
be included, the effect of the
assignment inverted. Note that this
permitted and inheritable capability
sets, on top of what
<varname>Capabilities=</varname>
- does. If this option is not used the
+ does. If this option is not used, the
capability bounding set is not
modified on process execution, hence
no limits on the capabilities of the
appear more than once in which case
the bounding sets are merged. If the
empty string is assigned to this
- option the bounding set is reset to
+ 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
+ further argument), the bounding set is
reset to the full set of available
capabilities, also undoing any
previous settings.</para></listitem>
<term><varname>SecureBits=</varname></term>
<listitem><para>Controls the secure
bits set for the executed process. See
- <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details. Takes a list of strings:
<option>keep-caps</option>,
<option>keep-caps-locked</option>,
option may appear more than once in
which case the secure bits are
ORed. If the empty string is assigned
- to this option the bits are reset to
+ to this option, the bits are reset to
0.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Capabilities=</varname></term>
<listitem><para>Controls the
- <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
set for the executed process. Take a
capability string describing the
effective, permitted and inherited
capability sets as documented in
<citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
Note that these capability sets are
- usually influenced by the capabilities
+ usually influenced (and filtered) by the capabilities
attached to the executed file. Due to
that
<varname>CapabilityBoundingSet=</varname>
<term><varname>ReadOnlyDirectories=</varname></term>
<term><varname>InaccessibleDirectories=</varname></term>
- <listitem><para>Sets up a new
- file system namespace for executed
+ <listitem><para>Sets up a new file
+ system namespace for executed
processes. These options may be used
to limit access a process might have
to the main file system
processes inside the namespace. Note
that restricting access with these
options does not extend to submounts
- of a directory. You must list
- submounts separately in these settings
- to ensure the same limited
- access. These options may be specified
+ of a directory that are created later
+ on. These options may be specified
more than once in which case all
directories listed will have limited
access from within the namespace. If
the empty string is assigned to this
- option the specific list is reset, and
- all prior assignments have no
+ option, the specific list is reset,
+ and all prior assignments have no
effect.</para>
<para>Paths in
<varname>ReadOnlyDirectories=</varname>
may be prefixed with
<literal>-</literal>, in which case
they will be ignored when they do not
- exist.</para></listitem>
+ exist. Note that using this
+ setting will disconnect propagation of
+ mounts from the service to the host
+ (propagation in the opposite direction
+ continues to work). This means that
+ this setting may not be used for
+ services which shall be able to
+ install mount points in the main mount
+ namespace.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PrivateTmp=</varname></term>
<listitem><para>Takes a boolean
- argument. If true sets up a new file
+ 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 are not shared by
- processes outside of the
+ <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 the
process, but makes sharing between
processes via
<filename>/tmp</filename> or
<filename>/var/tmp</filename>
- impossible. All temporary data created
- by service will be removed after service
- is stopped. Defaults to
- false.</para></listitem>
+ 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 private
+ <filename>/tmp</filename> and
+ <filename>/var/tmp</filename>
+ namespace by using the
+ <varname>JoinsNamespaceOf=</varname>
+ directive, see
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details. Note that using this
+ setting will disconnect propagation of
+ mounts from the service to the host
+ (propagation in the opposite direction
+ continues to work). This means that
+ this setting may not be used for
+ services which shall be able to install
+ mount points in the main mount
+ namespace.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>PrivateDevices=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If true, sets up a new /dev
+ namespace for the executed processes
+ and only adds API pseudo devices such
+ as <filename>/dev/null</filename>,
+ <filename>/dev/zero</filename> or
+ <filename>/dev/random</filename> (as
+ well as the pseudo TTY subsystem) to
+ it, but no physical devices such as
+ <filename>/dev/sda</filename>. This is
+ useful to securely turn off physical
+ device access by the executed
+ process. Defaults to false. Enabling
+ this option will also remove
+ <constant>CAP_MKNOD</constant> from
+ the capability bounding set for the
+ unit (see above), and set
+ <varname>DevicePolicy=closed</varname>
+ (see
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details). Note that using this
+ setting will disconnect propagation of
+ mounts from the service to the host
+ (propagation in the opposite direction
+ continues to work). This means that
+ this setting may not be used for
+ services which shall be able to
+ install mount points in the main mount
+ namespace.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PrivateNetwork=</varname></term>
<listitem><para>Takes a boolean
- argument. If true sets up a new
+ argument. If true, sets up a new
network namespace for the executed
processes and configures only the
loopback network device
available to the executed process.
This is useful to securely turn off
network access by the executed
- process. Defaults to
- false.</para></listitem>
+ process. Defaults to false. It is
+ possible to run two or more units
+ within the same private network
+ namespace by using the
+ <varname>JoinsNamespaceOf=</varname>
+ directive, see
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details. Note that this option
+ will disconnect all socket families
+ from the host, this includes
+ AF_NETLINK and AF_UNIX. The latter has
+ the effect that AF_UNIX sockets in the
+ abstract socket namespace will become
+ unavailable to the processes (however,
+ those located in the file system will
+ continue to be
+ accessible).</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ProtectSystem=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument or
+ <literal>full</literal>. If true,
+ mounts the <filename>/usr</filename>
+ directory read-only for processes
+ invoked by this unit. If set to
+ <literal>full</literal>, the
+ <filename>/etc</filename> directory is mounted
+ read-only, too. This setting ensures
+ that any modification of the vendor
+ supplied operating system (and
+ optionally its configuration) is
+ prohibited for the service. It is
+ recommended to enable this setting for
+ all long-running services, unless they
+ are involved with system updates or
+ need to modify the operating system in
+ other ways. Note however that
+ processes retaining the CAP_SYS_ADMIN
+ capability can undo the effect of this
+ setting. This setting is hence
+ particularly useful for daemons which
+ have this capability removed, for
+ example with
+ <varname>CapabilityBoundingSet=</varname>. Defaults
+ to off.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ProtectHome=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument or
+ <literal>read-only</literal>. If true,
+ the directories
+ <filename>/home</filename> and
+ <filename>/run/user</filename> are
+ made inaccessible and empty for
+ processes invoked by this unit. If set
+ to <literal>read-only</literal>, the
+ two directores are made read-only
+ instead. It is recommended to enable
+ this setting for all long-running
+ services (in particular network-facing
+ ones), to ensure they cannot get access
+ to private user data, unless the
+ services actually require access to
+ the user's private data. Note however
+ that processes retaining the
+ CAP_SYS_ADMIN capability can undo the
+ effect of this setting. This setting
+ is hence particularly useful for
+ daemons which have this capability
+ removed, for example with
+ <varname>CapabilityBoundingSet=</varname>. Defaults
+ to off.</para></listitem>
</varlistentry>
<varlistentry>
<option>shared</option>,
<option>slave</option> or
<option>private</option>, which
- control whether the file system
- namespace set up for this unit's
- processes will receive or propagate
- new mounts. See
+ control whether mounts in the file
+ system namespace set up for this
+ unit's processes will receive or
+ propagate mounts or unmounts. See
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details. Default to
- <option>shared</option>.</para></listitem>
+ for details. Defaults to
+ <option>shared</option>. Use
+ <option>shared</option> to ensure that
+ mounts and unmounts are propagated
+ from the host to the container and
+ vice versa. Use <option>slave</option>
+ to run processes so that none of their
+ mounts and unmounts will propagate to
+ the host. Use <option>private</option>
+ to also ensure that no mounts and
+ unmounts from the host will propagate
+ into the unit processes'
+ namespace. Note that
+ <option>slave</option> means that file
+ systems mounted on the host might stay
+ mounted continously in the unit's
+ namespace, and thus keep the device
+ busy. Note that the file system
+ namespace related options
+ (<varname>PrivateTmp=</varname>,
+ <varname>PrivateDevices=</varname>,
+ <varname>ReadOnlySystem=</varname>,
+ <varname>ProtectedHome=</varname>,
+ <varname>ReadOnlyDirectories=</varname>,
+ <varname>InaccessibleDirectories=</varname>
+ and
+ <varname>ReadWriteDirectories=</varname>)
+ require that mount and unmount
+ propagation from the unit's file
+ system namespace is disabled, and
+ hence downgrade
+ <option>shared</option> to
+ <option>slave</option>.
+ </para></listitem>
</varlistentry>
<varlistentry>
entries must be created and cleared
before and after execution. If the
configured string is longer than four
- characters it is truncated and the
+ characters, it is truncated and the
terminal four characters are
used. This setting interprets %I style
string replacements. This setting is
this service.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>SELinuxContext=</varname></term>
+
+ <listitem><para>Set the SELinux
+ security context of the executed
+ process. If set, this will override
+ the automated domain
+ transition. However, the policy still
+ needs to autorize the transition. This
+ directive is ignored if SELinux is
+ disabled. If prefixed by
+ <literal>-</literal>, all errors will
+ be ignored. See
+ <citerefentry><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <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.
+ </para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>IgnoreSIGPIPE=</varname></term>
<varlistentry>
<term><varname>SystemCallFilter=</varname></term>
- <listitem><para>Takes a space-separated
- list of system call
+ <listitem><para>Takes a
+ space-separated list of system call
names. If this setting is used, all
system calls executed by the unit
- process except for the listed ones
+ processes except for the listed ones
will result in immediate process
termination with the
<constant>SIGSYS</constant> signal
(whitelisting). If the first character
- of the list is <literal>~</literal>
+ of the list is <literal>~</literal>,
the effect is inverted: only the
listed system calls will result in
immediate process termination
- (blacklisting). If this option is used
+ (blacklisting). If running in user
+ mode and this option is used,
<varname>NoNewPrivileges=yes</varname>
- is implied. This feature makes use of
- the Secure Computing Mode 2 interfaces
- of the kernel ('seccomp filtering')
- and is useful for enforcing a minimal
+ is implied. This feature makes use of the
+ Secure Computing Mode 2 interfaces of
+ the kernel ('seccomp filtering') and
+ is useful for enforcing a minimal
sandboxing environment. Note that the
<function>execve</function>,
<function>rt_sigreturn</function>,
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
+ assigned, the filter is reset, all
prior assignments will have no
- effect.</para></listitem>
+ effect.</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></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SystemCallErrorNumber=</varname></term>
+
+ <listitem><para>Takes an
+ <literal>errno</literal> error number
+ name to return when the system call
+ filter configured with
+ <varname>SystemCallFilter=</varname>
+ is triggered, instead of terminating
+ the process immediately. Takes an
+ error name such as
+ <constant>EPERM</constant>,
+ <constant>EACCES</constant> or
+ <constant>EUCLEAN</constant>. When this
+ setting is not used, or when the empty
+ string is assigned, the process will be
+ terminated immediately when the filter
+ is triggered.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SystemCallArchitectures=</varname></term>
+
+ <listitem><para>Takes a space
+ separated list of architecture
+ identifiers to include in the system
+ call filter. The known architecture
+ identifiers are
+ <constant>x86</constant>,
+ <constant>x86-64</constant>,
+ <constant>x32</constant>,
+ <constant>arm</constant> as well as
+ the special identifier
+ <constant>native</constant>. Only
+ system calls of the specified
+ architectures will be permitted to
+ processes of this unit. This is an
+ effective way to disable compatibility
+ with non-native architectures for
+ processes, for example to prohibit
+ execution of 32-bit x86 binaries on
+ 64-bit x86-64 systems. The special
+ <constant>native</constant> identifier
+ implicitly maps to the native
+ architecture of the system (or more
+ strictly: to the architecture the
+ system manager is compiled for). If
+ running in user mode and this option
+ is used,
+ <varname>NoNewPrivileges=yes</varname>
+ is implied. Note that setting this
+ option to a non-empty list implies
+ that <constant>native</constant> is
+ included too. By default, this option
+ is set to the empty list, i.e. no
+ architecture system call filtering is
+ applied.</para></listitem>
+ </varlistentry>
+
+ <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><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 and is ignored (but works
+ correctly on x86-64). If running in user
+ mode and this option is used,
+ <varname>NoNewPrivileges=yes</varname>
+ is implied. By default, no
+ restriction applies, all address
+ families are accessible to
+ processes. If assigned the empty
+ string, any previous list changes are
+ undone.</para>
+
+ <para>Use this option to limit
+ exposure of processes to remote
+ systems, in particular via exotic
+ network protocols. Note that in most
+ cases, the local
+ <constant>AF_UNIX</constant> address
+ family should be included in the
+ configured whitelist as it is
+ frequently used for local
+ communication, including for
+ <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ logging.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Personality=</varname></term>
+
+ <listitem><para>Controls which
+ kernel architecture
+ <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ shall report, when invoked by unit
+ processes. Takes one of
+ <constant>x86</constant> and
+ <constant>x86-64</constant>. This is
+ useful when running 32-bit services on
+ a 64-bit host system. If not specified,
+ the personality is left unmodified and
+ thus reflects the personality of the
+ host system's
+ kernel.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RuntimeDirectory=</varname></term>
+ <term><varname>RuntimeDirectoryMode=</varname></term>
+
+ <listitem><para>Takes a list of
+ directory names. If set, one or more
+ directories by the specified names
+ will be created below
+ <filename>/run</filename> (for system
+ services) or below
+ <varname>$XDG_RUNTIME_DIR</varname>
+ (for user services) when the unit is
+ started, and removed when the unit is
+ stopped. The directories will have the
+ access mode specified in
+ <varname>RuntimeDirectoryMode=</varname>,
+ and will be owned by the user and
+ group specified in
+ <varname>User=</varname> and
+ <varname>Group=</varname>. Use this to
+ manage one or more runtime directories
+ of the unit and bind their lifetime to
+ the daemon runtime. The specified
+ directory names must be relative, and
+ may not include a
+ <literal>/</literal>, i.e. must refer
+ to simple directories to create or
+ remove. This is particularly useful
+ for unprivileged daemons that cannot
+ create runtime directories in
+ <filename>/run</filename> due to lack
+ of privileges, and to make sure the
+ runtime directory is cleaned up
+ automatically after use. For runtime
+ directories that require more complex
+ or different configuration or lifetime
+ guarantees, please consider using
+ <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Environment variables in spawned processes</title>
+
+ <para>Processes started by the system are executed in
+ a clean environment in which select variables
+ listed below are set. System processes started by systemd
+ do not inherit variables from PID 1, but processes
+ started by user systemd instances inherit all
+ environment variables from the user systemd instance.
+ </para>
+
+ <variablelist class='environment-variables'>
+ <varlistentry>
+ <term><varname>$PATH</varname></term>
+
+ <listitem><para>Colon-separated list
+ of directiories to use when launching
+ executables. Systemd uses a fixed
+ value of
+ <filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$LANG</varname></term>
+
+ <listitem><para>Locale. Can be set in
+ <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ or on the kernel command line (see
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$USER</varname></term>
+ <term><varname>$LOGNAME</varname></term>
+ <term><varname>$HOME</varname></term>
+ <term><varname>$SHELL</varname></term>
+
+ <listitem><para>User name (twice), home
+ directory, and the login shell.
+ The variables are set for the units that
+ have <varname>User=</varname> set,
+ which includes user
+ <command>systemd</command> instances.
+ See
+ <citerefentry><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$XDG_RUNTIME_DIR</varname></term>
+
+ <listitem><para>The directory for volatile
+ state. Set for the user <command>systemd</command>
+ instance, and also in user sessions.
+ See
+ <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$XDG_SESSION_ID</varname></term>
+ <term><varname>$XDG_SEAT</varname></term>
+ <term><varname>$XDG_VTNR</varname></term>
+
+ <listitem><para>The identifier of the
+ session, the seat name, and
+ virtual terminal of the session. Set
+ by
+ <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ for login sessions.
+ <varname>$XDG_SEAT</varname> and
+ <varname>$XDG_VTNR</varname> will
+ only be set when attached to a seat and a
+ tty.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$MAINPID</varname></term>
+
+ <listitem><para>The PID of the units
+ main process if it is known. This is
+ only set for control processes as
+ invoked by
+ <varname>ExecReload=</varname> and
+ similar. </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$MANAGERPID</varname></term>
+
+ <listitem><para>The PID of the user
+ <command>systemd</command> instance,
+ set for processes spawned by it.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$LISTEN_FDS</varname></term>
+ <term><varname>$LISTEN_PID</varname></term>
+
+ <listitem><para>Information about file
+ descriptors passed to a service for
+ socket activation. See
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$TERM</varname></term>
+
+ <listitem><para>Terminal type, set
+ only for units connected to a terminal
+ (<varname>StandardInput=tty</varname>,
+ <varname>StandardOutput=tty</varname>,
+ or
+ <varname>StandardError=tty</varname>).
+ See
+ <citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Additional variables may be configured by the
+ following means: for processes spawned in specific
+ units, use the <varname>Environment=</varname> and
+ <varname>EnvironmentFile=</varname> options above; to
+ specify variables globally, use
+ <varname>DefaultEnvironment=</varname> (see
+ <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
+ or the kernel option
+ <varname>systemd.setenv=</varname> (see
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Additional
+ variables may also be set through PAM,
+ cf. <citerefentry project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+ </refsect1>
+
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.cgroup</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>