chiark / gitweb /
man: document equivalence between Limit directives and ulimit
[elogind.git] / man / systemd.exec.xml
index 3f27d13c38201471e5ee2f2a9c76ce3eac931d8b..1bc6bafa473dd79b88b8e79fe90ab0c326c2200a 100644 (file)
                                 directory path. Sets the root
                                 directory for executed processes, with
                                 the
-                                <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+                                <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
 
                                 <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>
                                 <option>tty</option>,
                                 <option>tty-force</option>,
                                 <option>tty-fail</option> or
-                                <option>socket</option>. If
-                                <option>null</option> is selected,
-                                standard input will be connected to
+                                <option>socket</option>.</para>
+
+                                <para>If <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,
-                                standard input is connected to a TTY
-                                (as configured by
+                                will result in immediate EOF.</para>
+
+                                <para>If <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
-                                executed process waits until the current
-                                controlling process releases the
-                                terminal.
-                                <option>tty-force</option>
-                                is similar to <option>tty</option>,
-                                but the executed process is forcefully
-                                and immediately made the controlling
+                                being controlled by another process,
+                                the executed process waits until the
+                                current controlling process releases
+                                the terminal.</para>
+
+                                <para><option>tty-force</option> is similar
+                                to <option>tty</option>, but the
+                                executed process is forcefully and
+                                immediately made the controlling
                                 process of the terminal, potentially
                                 removing previous controlling
                                 processes from the
-                                terminal. <option>tty-fail</option> is
+                                terminal.</para>
+
+                                <para><option>tty-fail</option> is
                                 similar to <option>tty</option> but if
                                 the terminal already has a controlling
                                 process start-up of the executed
-                                process fails.  The
-                                <option>socket</option> option is only
-                                valid in socket-activated services,
-                                and only when the socket configuration
-                                file (see
+                                process fails.</para>
+
+                                <para>The <option>socket</option>
+                                option is only valid in
+                                socket-activated services, and only
+                                when the socket configuration file
+                                (see
                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                                 for details) specifies a single socket
                                 only. If this option is set, standard
                                 with daemons designed for use with the
                                 traditional
                                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
-                                daemon. This setting defaults to
+                                daemon.</para>
+
+                                <para>This setting defaults to
                                 <option>null</option>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 of <option>inherit</option>,
                                 <option>null</option>,
                                 <option>tty</option>,
+                                <option>journal</option>,
                                 <option>syslog</option>,
                                 <option>kmsg</option>,
-                                <option>journal</option>,
+                                <option>journal+console</option>,
                                 <option>syslog+console</option>,
-                                <option>kmsg+console</option>,
-                                <option>journal+console</option> or
-                                <option>socket</option>. If set to
-                                <option>inherit</option>, the file
-                                descriptor of standard input is
-                                duplicated for standard output. If set
-                                to <option>null</option>, standard
-                                output will be connected to
+                                <option>kmsg+console</option> or
+                                <option>socket</option>.</para>
+
+                                <para><option>inherit</option>
+                                duplicates the file descriptor of
+                                standard input for standard
+                                output.</para>
+
+                                <para><option>null</option> connects
+                                standard output to
                                 <filename>/dev/null</filename>,
                                 i.e. everything written to it will be
-                                lost. If set to <option>tty</option>,
-                                standard output will be connected to a
-                                tty (as configured via
+                                lost.</para>
+
+                                <para><option>tty</option> connects
+                                standard output to a tty (as
+                                configured via
                                 <varname>TTYPath=</varname>, see
                                 below). If the TTY is used for output
                                 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>
-                                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>
-                                connects it with the journal which is
-                                accessible via
-                                <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-                                (Note that everything that is written
-                                to syslog or kmsg is implicitly stored
-                                in the journal as well, those options
-                                are hence supersets of this
-                                one). <option>syslog+console</option>,
-                                <option>journal+console</option> and
-                                <option>kmsg+console</option> work
-                                similarly but copy the output to the
-                                system console as
-                                well. <option>socket</option> connects
-                                standard output to a socket from
-                                socket activation, semantics are
-                                similar to the respective option of
-                                <varname>StandardInput=</varname>.
-                                This setting defaults to the value set
-                                with
+                                terminal.</para>
+
+                                <para><option>journal</option>
+                                connects standard output with the
+                                journal which is accessible via
+                                <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+                                Note that everything that is written
+                                to syslog or kmsg (see below) is
+                                implicitly stored in the journal as
+                                well, the specific two options listed
+                                below are hence supersets of this
+                                one.</para>
+
+                                <para><option>syslog</option> connects
+                                standard output to the <citerefentry
+                                project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                                system syslog service, in addition to
+                                the journal. Note that the journal
+                                daemon is usually configured to
+                                forward everything it receives to
+                                syslog anyway, in which case this
+                                option is no different from
+                                <option>journal</option>.</para>
+
+                                <para><option>kmsg</option> connects
+                                standard output with the kernel log
+                                buffer which is accessible via
+                                <citerefentry
+                                project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                                in addition to the journal. The
+                                journal daemon might be configured to
+                                send all logs to kmsg anyway, in which
+                                case this option is no different from
+                                <option>journal</option>.</para>
+
+                                <para><option>journal+console</option>,
+                                <option>syslog+console</option> and
+                                <option>kmsg+console</option> work in
+                                a similar way as the three options
+                                above but copy the output to the
+                                system console as well.</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>.</para>
+
+                                <para>This setting defaults to the
+                                value set with
                                 <option>DefaultStandardOutput=</option>
                                 in
                                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <varlistentry>
                                 <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,
-                                defaults to the process name of the
-                                executed process. This option is only
-                                useful when
+                                to prefix log lines sent to the
+                                logging system or the kernel log
+                                buffer with. If not set, defaults to
+                                the process name of the executed
+                                process. This option is only useful
+                                when
                                 <varname>StandardOutput=</varname> or
                                 <varname>StandardError=</varname> are
-                                set to <option>syslog</option> or
-                                <option>kmsg</option>.</para></listitem>
+                                set to <option>syslog</option>,
+                                <option>journal</option> or
+                                <option>kmsg</option> (or to the same
+                                settings in combination with
+                                <option>+console</option>).</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 <term><varname>SyslogFacility=</varname></term>
                                 <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
                                 <varname>infinity</varname> to
                                 configure no limit on a specific
                                 resource.</para></listitem>
+
+                                <table>
+                                        <title>Limit directives and their equivalent with ulimit</title>
+
+                                        <tgroup cols='2'>
+                                                <colspec colname='directive' />
+                                                <colspec colname='equivalent' />
+                                                <thead>
+                                                        <row>
+                                                                <entry>Directive</entry>
+                                                                <entry>ulimit equivalent</entry>
+                                                        </row>
+                                                </thead>
+                                                <tbody>
+                                                        <row>
+                                                                <entry>LimitCPU</entry>
+                                                                <entry>ulimit -t</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitFSIZE</entry>
+                                                                <entry>ulimit -f</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitDATA</entry>
+                                                                <entry>ulimit -d</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitSTACK</entry>
+                                                                <entry>ulimit -s</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitCORE</entry>
+                                                                <entry>ulimit -c</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitRSS</entry>
+                                                                <entry>ulimit -m</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitNOFILE</entry>
+                                                                <entry>ulimit -n</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitAS</entry>
+                                                                <entry>ulimit -v</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitNPROC</entry>
+                                                                <entry>ulimit -u</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitMEMLOCK</entry>
+                                                                <entry>ulimit -l</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitLOCKS</entry>
+                                                                <entry>ulimit -x</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitSIGPENDING</entry>
+                                                                <entry>ulimit -i</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitMSGQUEUE</entry>
+                                                                <entry>ulimit -q</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitNICE</entry>
+                                                                <entry>ulimit -e</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitRTPRIO</entry>
+                                                                <entry>ulimit -r</entry>
+                                                        </row>
+                                                        <row>
+                                                                <entry>LimitRTTIME</entry>
+                                                                <entry>No equivalent</entry>
+                                                        </row>
+                                                </tbody>
+                                        </tgroup>
+                                </table>
                         </varlistentry>
 
                         <varlistentry>
                                 <varname>User=</varname> setting. If
                                 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>
 
                                 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>,
                         <varlistentry>
                                 <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>
-                                for details. Takes a list of strings:
+                                bits set for the executed process.
+                                Takes a space-separated combination of
+                                options from the following list:
                                 <option>keep-caps</option>,
                                 <option>keep-caps-locked</option>,
                                 <option>no-setuid-fixup</option>,
                                 <option>no-setuid-fixup-locked</option>,
-                                <option>noroot</option> and/or
+                                <option>noroot</option>, and
                                 <option>noroot-locked</option>. This
                                 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
-                                0.</para></listitem>
+                                which case the secure bits are ORed.
+                                If the empty string is assigned to
+                                this option, the bits are reset to 0.
+                                See <citerefentry
+                                project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                for details.</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>
-                                is probably the much more useful
+                                is probably a much more useful
                                 setting.</para></listitem>
                         </varlistentry>
 
                                 <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>
                                 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 directories 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>
                                 <term><varname>MountFlags=</varname></term>
 
                                 namespace. Note that
                                 <option>slave</option> means that file
                                 systems mounted on the host might stay
-                                mounted continously in the unit's
+                                mounted continuously 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>ProtectSystem=</varname>,
+                                <varname>ProtectHome=</varname>,
                                 <varname>ReadOnlyDirectories=</varname>,
                                 <varname>InaccessibleDirectories=</varname>
                                 and
                                 </para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>SmackProcessLabel=</varname></term>
+
+                                <listitem><para>Takes a
+                                <option>SMACK64</option> security
+                                label as argument. The process
+                                executed by the unit will be started
+                                under this label and SMACK will decide
+                                whether the processes is allowed to
+                                run or not based on it. The process
+                                will continue to run under the label
+                                specified here unless the executable
+                                has its own
+                                <option>SMACK64EXEC</option> label, in
+                                which case the process will transition
+                                to run under that label. When not
+                                specified, the label that systemd is
+                                running under is used. This directive
+                                is ignored if SMACK is
+                                disabled.</para>
+
+                                <para>The value may be prefixed by
+                                <literal>-</literal>, in which case
+                                all errors will be ignored. An empty
+                                value may be specified to unset
+                                previous assignments.</para>
+                                </listitem>
+                        </varlistentry>
+
                         <varlistentry>
                                 <term><varname>IgnoreSIGPIPE=</varname></term>
 
                                 or
                                 <varname>StandardError=tty</varname>).
                                 See
-                                <citerefentry><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                                <citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
                                 </para></listitem>
                         </varlistentry>
                 </variablelist>
                 <varname>systemd.setenv=</varname> (see
                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Additional
                 variables may also be set through PAM,
-                cf. <citerefentry><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+                cf. <citerefentry project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
         </refsect1>
 
         <refsect1>
                   <title>See Also</title>
                   <para>
                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-                          <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+                          <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</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><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                          <citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                   </para>
         </refsect1>