chiark / gitweb /
resolved: set LLMNR TCP and UDP TTLs to the values suggested by the RFC
[elogind.git] / man / systemd.exec.xml
index d206d4f64564210aa0cedf913f263a5da0bc1caf..2f75915c2076d6aa4c31bb65d2020422c99b448e 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>
                                 <para>The files listed with this
                                 directive will be read shortly before
                                 the process is executed (more
-                                specifically, this means after all
+                                specifically, after all
                                 processes from a previous unit state
                                 terminated. This means you can
                                 generate these files in one unit
                                 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>
                                 <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>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>,
                                 <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>,
                         <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>
                                 processes via
                                 <filename>/tmp</filename> or
                                 <filename>/var/tmp</filename>
-                                impossible. If this is enabled all
+                                impossible. If this is enabled, all
                                 temporary files created by a service
                                 in these directories will be removed
                                 after the service is stopped. Defaults
                                 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>
                                 <term><varname>MountFlags=</varname></term>
 
                                 namespace related options
                                 (<varname>PrivateTmp=</varname>,
                                 <varname>PrivateDevices=</varname>,
+                                <varname>ReadOnlySystem=</varname>,
+                                <varname>ProtectedHome=</varname>,
                                 <varname>ReadOnlyDirectories=</varname>,
                                 <varname>InaccessibleDirectories=</varname>
                                 and
                         <varlistentry>
                                 <term><varname>AppArmorProfile=</varname></term>
 
-                                <listitem><para>Take a profile name as argument.
+                                <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.
                                 correctly on x86-64). If running in user
                                 mode and this option is used,
                                 <varname>NoNewPrivileges=yes</varname>
-                                is implied. By default no
+                                is implied. By default, no
                                 restriction applies, all address
                                 families are accessible to
                                 processes. If assigned the empty
-                                string any previous list changes are
+                                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
+                                cases, the local
                                 <constant>AF_UNIX</constant> address
                                 family should be included in the
                                 configured whitelist as it is
                                 <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
+                                a 64-bit host system. If not specified,
                                 the personality is left unmodified and
                                 thus reflects the personality of the
                                 host system's
                                 <term><varname>RuntimeDirectoryMode=</varname></term>
 
                                 <listitem><para>Takes a list of
-                                directory names. If set one or more
+                                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
+                                started, and removed when the unit is
                                 stopped. The directories will have the
                                 access mode specified in
                                 <varname>RuntimeDirectoryMode=</varname>,
                                 <literal>/</literal>, i.e. must refer
                                 to simple directories to create or
                                 remove. This is particularly useful
-                                for unpriviliges daemons that cannot
+                                for unprivileged daemons that cannot
                                 create runtime directories in
                                 <filename>/run</filename> due to lack
                                 of privileges, and to make sure the
                                 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,
-                c.f. <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>
                           <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>