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+ SPDX-License-Identifier: LGPL-2.1+
+
This file is part of systemd.
Copyright 2013 Zbigniew Jędrzejewski-Szmek
-
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-->
<refentry id="systemd.resource-control">
<varlistentry>
<term><option>CPU</option></term>
<listitem>
- <para>Due to the lack of consensus in the kernel community, the CPU controller support on the unified
- control group hierarchy requires out-of-tree kernel patches. See <ulink
- url="https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu">cgroup-v2-cpu.txt</ulink>.</para>
-
<para><varname>CPUWeight=</varname> and <varname>StartupCPUWeight=</varname> replace
<varname>CPUShares=</varname> and <varname>StartupCPUShares=</varname>, respectively.</para>
<varlistentry>
<term><option>IO</option></term>
<listitem>
- <para><varname>IO</varname> prefixed settings are superset of and replace <varname>BlockIO</varname>
+ <para><varname>IO</varname> prefixed settings are a superset of and replace <varname>BlockIO</varname>
prefixed ones. On unified hierarchy, IO resource control also applies to buffered writes.</para>
</listitem>
</varlistentry>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><varname>IPAccounting=</varname></term>
+
+ <listitem>
+ <para>Takes a boolean argument. If true, turns on IPv4 and IPv6 network traffic accounting for packets sent
+ or received by the unit. When this option is turned on, all IPv4 and IPv6 sockets created by any process of
+ the unit are accounted for.</para>
+
+ <para>When this option is used in socket units, it applies to all IPv4 and IPv6 sockets
+ associated with it (including both listening and connection sockets where this applies). Note that for
+ socket-activated services, this configuration setting and the accounting data of the service unit and the
+ socket unit are kept separate, and displayed separately. No propagation of the setting and the collected
+ statistics is done, in either direction. Moreover, any traffic sent or received on any of the socket unit's
+ sockets is accounted to the socket unit — and never to the service unit it might have activated, even if the
+ socket is used by it.</para>
+
+ <para>The system default for this setting may be controlled with <varname>DefaultIPAccounting=</varname> in
+ <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IPAddressAllow=<replaceable>ADDRESS[/PREFIXLENGTH]…</replaceable></varname></term>
+ <term><varname>IPAddressDeny=<replaceable>ADDRESS[/PREFIXLENGTH]…</replaceable></varname></term>
+
+ <listitem>
+ <para>Turn on address range network traffic filtering for packets sent and received over AF_INET and AF_INET6
+ sockets. Both directives take a space separated list of IPv4 or IPv6 addresses, each optionally suffixed
+ with an address prefix length (separated by a <literal>/</literal> character). If the latter is omitted, the
+ address is considered a host address, i.e. the prefix covers the whole address (32 for IPv4, 128 for IPv6).
+ </para>
+
+ <para>The access lists configured with this option are applied to all sockets created by processes of this
+ unit (or in the case of socket units, associated with it). The lists are implicitly combined with any lists
+ configured for any of the parent slice units this unit might be a member of. By default all access lists are
+ empty. When configured the lists are enforced as follows:</para>
+
+ <itemizedlist>
+ <listitem><para>Access will be granted in case its destination/source address matches any entry in the
+ <varname>IPAddressAllow=</varname> setting.</para></listitem>
+
+ <listitem><para>Otherwise, access will be denied in case its destination/source address matches any entry
+ in the <varname>IPAddressDeny=</varname> setting.</para></listitem>
+
+ <listitem><para>Otherwise, access will be granted.</para></listitem>
+ </itemizedlist>
+
+ <para>In order to implement a whitelisting IP firewall, it is recommended to use a
+ <varname>IPAddressDeny=</varname><constant>any</constant> setting on an upper-level slice unit (such as the
+ root slice <filename>-.slice</filename> or the slice containing all system services
+ <filename>system.slice</filename> – see
+ <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+ details on these slice units), plus individual per-service <varname>IPAddressAllow=</varname> lines
+ permitting network access to relevant services, and only them.</para>
+
+ <para>Note that for socket-activated services, the IP access list configured on the socket unit applies to
+ all sockets associated with it directly, but not to any sockets created by the ultimately activated services
+ for it. Conversely, the IP access list configured for the service is not applied to any sockets passed into
+ the service via socket activation. Thus, it is usually a good idea, to replicate the IP access lists on both
+ the socket and the service unit, however it often makes sense to maintain one list more open and the other
+ one more restricted, depending on the usecase.</para>
+
+ <para>If these settings are used multiple times in the same unit the specified lists are combined. If an
+ empty string is assigned to these settings the specific access list is reset and all previous settings undone.</para>
+
+ <para>In place of explicit IPv4 or IPv6 address and prefix length specifications a small set of symbolic
+ names may be used. The following names are defined:</para>
+
+ <table>
+ <title>Special address/network names</title>
+
+ <tgroup cols='3'>
+ <colspec colname='name'/>
+ <colspec colname='definition'/>
+ <colspec colname='meaning'/>
+
+ <thead>
+ <row>
+ <entry>Symbolic Name</entry>
+ <entry>Definition</entry>
+ <entry>Meaning</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry><constant>any</constant></entry>
+ <entry>0.0.0.0/0 ::/0</entry>
+ <entry>Any host</entry>
+ </row>
+
+ <row>
+ <entry><constant>localhost</constant></entry>
+ <entry>127.0.0.0/8 ::1/128</entry>
+ <entry>All addresses on the local loopback</entry>
+ </row>
+
+ <row>
+ <entry><constant>link-local</constant></entry>
+ <entry>169.254.0.0/16 fe80::/64</entry>
+ <entry>All link-local IP addresses</entry>
+ </row>
+
+ <row>
+ <entry><constant>multicast</constant></entry>
+ <entry>224.0.0.0/4 ff00::/8</entry>
+ <entry>All IP multicasting addresses</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>Note that these settings might not be supported on some systems (for example if eBPF control group
+ support is not enabled in the underlying kernel or container manager). These settings will have no effect in
+ that case. If compatibility with such systems is desired it is hence recommended to not exclusively rely on
+ them for IP security.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>DeviceAllow=</varname></term>
<term><varname>Delegate=</varname></term>
<listitem>
- <para>Turns on delegation of further resource control
- partitioning to processes of the unit. For unprivileged
- services (i.e. those using the <varname>User=</varname>
- setting), this allows processes to create a subhierarchy
- beneath its control group path. For privileged services and
- scopes, this ensures the processes will have all control
- group controllers enabled.</para>
+ <para>Turns on delegation of further resource control partitioning to processes of the unit. Units where this
+ is enabled may create and manage their own private subhierarchy of control groups below the control group of
+ the unit itself. For unprivileged services (i.e. those using the <varname>User=</varname> setting) the unit's
+ control group will be made accessible to the relevant user. When enabled the service manager will refrain
+ from manipulating control groups or moving processes below the unit's control group, so that a clear concept
+ of ownership is established: the control group tree above the unit's control group (i.e. towards the root
+ control group) is owned and managed by the service manager of the host, while the control group tree below
+ the unit's control group is owned and managed by the unit itself. Takes either a boolean argument or a list
+ of control group controller names. If true, delegation is turned on, and all supported controllers are
+ enabled for the unit, making them available to the unit's processes for management. If false, delegation is
+ turned off entirely (and no additional controllers are enabled). If set to a list of controllers, delegation
+ is turned on, and the specified controllers are enabled for the unit. Note that additional controllers than
+ the ones specified might be made available as well, depending on configuration of the containing slice unit
+ or other units contained in it. Note that assigning the empty string will enable delegation, but reset the
+ list of controllers, all assignments prior to this will have no effect. Defaults to false.</para>
+
+ <para>Note that controller delegation to less privileged code is only safe on the unified control group
+ hierarchy. Accordingly, access to the specified controllers will not be granted to unprivileged services on
+ the legacy hierarchy, even when requested.</para>
+
+ <para>The following controller names may be specified: <option>cpu</option>, <option>cpuacct</option>,
+ <option>io</option>, <option>blkio</option>, <option>memory</option>, <option>devices</option>,
+ <option>pids</option>. Not all of these controllers are available on all kernels however, and some are
+ specific to the unified hierarchy while others are specific to the legacy hierarchy. Also note that the
+ kernel might support further controllers, which aren't covered here yet as delegation is either not supported
+ at all for them or not defined cleanly.</para>
</listitem>
</varlistentry>
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