chiark / gitweb /
execute: support syscall filtering using seccomp filters
[elogind.git] / man / systemd.exec.xml
index 01b638f5ac863839cf75f9e8414cd8c06b100327..6e55d8dfcf87c62b279bcf4a07dd6f83bbfd0fe5 100644 (file)
@@ -44,7 +44,7 @@
 
         <refnamediv>
                 <refname>systemd.exec</refname>
-                <refpurpose>systemd execution environment configuration</refpurpose>
+                <refpurpose>Execution environment configuration</refpurpose>
         </refnamediv>
 
         <refsynopsisdiv>
 
                                 <listitem><para>Takes an absolute
                                 directory path. Sets the working
-                                directory for executed
-                                processes.</para></listitem>
+                                directory for executed processes. If
+                                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
+                                user.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 prefixes may be disabled with
                                 <varname>SyslogLevelPrefix=</varname>,
                                 see below. For details see
-                                <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+                                <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 
                                 Defaults to
                                 <option>info</option>.</para></listitem>
                                 these prefixes is disabled and the
                                 logged lines are passed on as-is. For
                                 details about this prefixing see
-                                <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+                                <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
                                 Defaults to true.</para></listitem>
                         </varlistentry>
 
                                 <term><varname>BlockIOWriteBandwidth=</varname></term>
 
                                 <listitem><para>Set the per-device
-                                overall block IO bandwith limit for
+                                overall block IO bandwidth limit for
                                 the executed processes. Takes a space
                                 separated pair of a file path and a
-                                bandwith value (in bytes per second)
+                                bandwidth value (in bytes per second)
                                 to specify the device specific
                                 bandwidth. The file path may be
                                 specified as path to a block device
                                 node or as any other file in which
                                 case the backing block device of the
                                 file system of the file is determined.
-                                If the bandwith is suffixed with K, M,
-                                G, or T the specified bandwith is
+                                If the bandwidth is suffixed with K, M,
+                                G, or T the specified bandwidth is
                                 parsed as Kilobytes, Megabytes,
                                 Gigabytes, resp. Terabytes (Example:
                                 "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0
                                 and
                                 <literal>blkio.write_bps_device</literal>
                                 control group attributes. Use this
-                                option multiple times to set bandwith
+                                option multiple times to set bandwidth
                                 limits for multiple devices. For
                                 details about these control group
                                 attributes see <ulink
                                 shell pipelines.</para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>NoNewPrivileges=</varname></term>
+
+                                <listitem><para>Takes a boolean
+                                argument. If true ensures that the
+                                service process and all its children
+                                can never gain new privileges. This
+                                option is more powerful than the respective
+                                secure bits flags (see above), as it
+                                also prohibits UID changes of any
+                                kind. This is the simplest, most
+                                effective way to ensure that a process
+                                and its children can never elevate
+                                privileges again.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>SystemCallFilter=</varname></term>
+
+                                <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
+                                will result in immediate process
+                                termination with the SIGSYS signal
+                                (whitelisting). If the first character
+                                of the list is <literal>~</literal>
+                                the effect is inverted: only the
+                                listed system calls will result in
+                                immediate process termination
+                                (blacklisting). If 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
+                                sandboxing environment. Note that the
+                                <function>execve</function>,
+                                <function>rt_sigreturn</function>,
+                                <function>sigreturn</function>,
+                                <function>exit_group</function>,
+                                <function>exit</function> system calls
+                                are implicitly whitelisted and don't
+                                need to be listed
+                                explicitly.</para></listitem>
+                        </varlistentry>
+
                 </variablelist>
         </refsect1>