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514094f9 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
dd1eb43b | 5 | |
c4d4b5a7 | 6 | <refentry id="systemd.exec" xmlns:xi="http://www.w3.org/2001/XInclude"> |
798d3a52 ZJS |
7 | <refentryinfo> |
8 | <title>systemd.exec</title> | |
9 | <productname>systemd</productname> | |
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10 | </refentryinfo> |
11 | ||
12 | <refmeta> | |
13 | <refentrytitle>systemd.exec</refentrytitle> | |
14 | <manvolnum>5</manvolnum> | |
15 | </refmeta> | |
16 | ||
17 | <refnamediv> | |
18 | <refname>systemd.exec</refname> | |
19 | <refpurpose>Execution environment configuration</refpurpose> | |
20 | </refnamediv> | |
21 | ||
22 | <refsynopsisdiv> | |
23 | <para><filename><replaceable>service</replaceable>.service</filename>, | |
24 | <filename><replaceable>socket</replaceable>.socket</filename>, | |
25 | <filename><replaceable>mount</replaceable>.mount</filename>, | |
26 | <filename><replaceable>swap</replaceable>.swap</filename></para> | |
27 | </refsynopsisdiv> | |
28 | ||
29 | <refsect1> | |
30 | <title>Description</title> | |
31 | ||
b8afec21 LP |
32 | <para>Unit configuration files for services, sockets, mount points, and swap devices share a subset of |
33 | configuration options which define the execution environment of spawned processes.</para> | |
34 | ||
35 | <para>This man page lists the configuration options shared by these four unit types. See | |
36 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for the common | |
37 | options of all unit configuration files, and | |
798d3a52 ZJS |
38 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
39 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
b8afec21 LP |
40 | <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, and |
41 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more | |
42 | information on the specific unit configuration files. The execution specific configuration options are configured | |
43 | in the [Service], [Socket], [Mount], or [Swap] sections, depending on the unit type.</para> | |
74b47bbd | 44 | |
c7458f93 | 45 | <para>In addition, options which control resources through Linux Control Groups (cgroups) are listed in |
74b47bbd ZJS |
46 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
47 | Those options complement options listed here.</para> | |
798d3a52 ZJS |
48 | </refsect1> |
49 | ||
c129bd5d | 50 | <refsect1> |
45f09f93 JL |
51 | <title>Implicit Dependencies</title> |
52 | ||
53 | <para>A few execution parameters result in additional, automatic dependencies to be added:</para> | |
54 | ||
55 | <itemizedlist> | |
b8afec21 LP |
56 | <listitem><para>Units with <varname>WorkingDirectory=</varname>, <varname>RootDirectory=</varname>, |
57 | <varname>RootImage=</varname>, <varname>RuntimeDirectory=</varname>, <varname>StateDirectory=</varname>, | |
58 | <varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname> or | |
59 | <varname>ConfigurationDirectory=</varname> set automatically gain dependencies of type | |
60 | <varname>Requires=</varname> and <varname>After=</varname> on all mount units required to access the specified | |
61 | paths. This is equivalent to having them listed explicitly in | |
62 | <varname>RequiresMountsFor=</varname>.</para></listitem> | |
63 | ||
3b121157 ZJS |
64 | <listitem><para>Similarly, units with <varname>PrivateTmp=</varname> enabled automatically get mount |
65 | unit dependencies for all mounts required to access <filename>/tmp/</filename> and | |
66 | <filename>/var/tmp/</filename>. They will also gain an automatic <varname>After=</varname> dependency | |
67 | on | |
68 | <citerefentry><refentrytitle>systemd-tmpfiles-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. | |
69 | </para></listitem> | |
45f09f93 | 70 | |
d2b84355 LP |
71 | <listitem><para>Units whose standard output or error output is connected to <option>journal</option> or |
72 | <option>kmsg</option> (or their combinations with console output, see below) automatically acquire | |
73 | dependencies of type <varname>After=</varname> on | |
b8afec21 | 74 | <filename>systemd-journald.socket</filename>.</para></listitem> |
5b0a76d1 LP |
75 | |
76 | <listitem><para>Units using <varname>LogNamespace=</varname> will automatically gain ordering and | |
77 | requirement dependencies on the two socket units associated with | |
78 | <filename>systemd-journald@.service</filename> instances.</para></listitem> | |
45f09f93 | 79 | </itemizedlist> |
c129bd5d LP |
80 | </refsect1> |
81 | ||
45f09f93 JL |
82 | <!-- We don't have any default dependency here. --> |
83 | ||
798d3a52 | 84 | <refsect1> |
b8afec21 | 85 | <title>Paths</title> |
798d3a52 | 86 | |
1448dfa6 AK |
87 | <para>The following settings may be used to change a service's view of the filesystem. Please note that the paths |
88 | must be absolute and must not contain a <literal>..</literal> path component.</para> | |
89 | ||
798d3a52 ZJS |
90 | <variablelist class='unit-directives'> |
91 | ||
92 | <varlistentry> | |
93 | <term><varname>WorkingDirectory=</varname></term> | |
94 | ||
d251207d LP |
95 | <listitem><para>Takes a directory path relative to the service's root directory specified by |
96 | <varname>RootDirectory=</varname>, or the special value <literal>~</literal>. Sets the working directory for | |
97 | executed processes. If set to <literal>~</literal>, the home directory of the user specified in | |
98 | <varname>User=</varname> is used. If not set, defaults to the root directory when systemd is running as a | |
99 | system instance and the respective user's home directory if run as user. If the setting is prefixed with the | |
100 | <literal>-</literal> character, a missing working directory is not considered fatal. If | |
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101 | <varname>RootDirectory=</varname>/<varname>RootImage=</varname> is not set, then |
102 | <varname>WorkingDirectory=</varname> is relative to the root of the system running the service manager. Note | |
103 | that setting this parameter might result in additional dependencies to be added to the unit (see | |
104 | above).</para></listitem> | |
798d3a52 ZJS |
105 | </varlistentry> |
106 | ||
107 | <varlistentry> | |
108 | <term><varname>RootDirectory=</varname></term> | |
109 | ||
d251207d LP |
110 | <listitem><para>Takes a directory path relative to the host's root directory (i.e. the root of the system |
111 | running the service manager). Sets the root directory for executed processes, with the <citerefentry | |
112 | project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry> system | |
113 | call. If this is used, it must be ensured that the process binary and all its auxiliary files are available in | |
114 | the <function>chroot()</function> jail. Note that setting this parameter might result in additional | |
115 | dependencies to be added to the unit (see above).</para> | |
116 | ||
5d997827 | 117 | <para>The <varname>MountAPIVFS=</varname> and <varname>PrivateUsers=</varname> settings are particularly useful |
c4d4b5a7 LP |
118 | in conjunction with <varname>RootDirectory=</varname>. For details, see below.</para> |
119 | ||
120 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
5d997827 LP |
121 | </varlistentry> |
122 | ||
915e6d16 LP |
123 | <varlistentry> |
124 | <term><varname>RootImage=</varname></term> | |
b8afec21 | 125 | |
19ac32cd LP |
126 | <listitem><para>Takes a path to a block device node or regular file as argument. This call is similar |
127 | to <varname>RootDirectory=</varname> however mounts a file system hierarchy from a block device node | |
128 | or loopback file instead of a directory. The device node or file system image file needs to contain a | |
129 | file system without a partition table, or a file system within an MBR/MS-DOS or GPT partition table | |
130 | with only a single Linux-compatible partition, or a set of file systems within a GPT partition table | |
131 | that follows the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions | |
fe65e88b YW |
132 | Specification</ulink>.</para> |
133 | ||
c4d4b5a7 LP |
134 | <para>When <varname>DevicePolicy=</varname> is set to <literal>closed</literal> or |
135 | <literal>strict</literal>, or set to <literal>auto</literal> and <varname>DeviceAllow=</varname> is | |
136 | set, then this setting adds <filename>/dev/loop-control</filename> with <constant>rw</constant> mode, | |
137 | <literal>block-loop</literal> and <literal>block-blkext</literal> with <constant>rwm</constant> mode | |
138 | to <varname>DeviceAllow=</varname>. See | |
fe65e88b YW |
139 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
140 | for the details about <varname>DevicePolicy=</varname> or <varname>DeviceAllow=</varname>. Also, see | |
c4d4b5a7 LP |
141 | <varname>PrivateDevices=</varname> below, as it may change the setting of |
142 | <varname>DevicePolicy=</varname>.</para> | |
143 | ||
33b58dfb LP |
144 | <para>Units making use of <varname>RootImage=</varname> automatically gain an |
145 | <varname>After=</varname> dependency on <filename>systemd-udevd.service</filename>.</para> | |
146 | ||
c4d4b5a7 | 147 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> |
915e6d16 LP |
148 | </varlistentry> |
149 | ||
18d73705 LB |
150 | <varlistentry> |
151 | <term><varname>RootImageOptions=</varname></term> | |
152 | ||
153 | <listitem><para>Takes a comma-separated list of mount options that will be used on disk images specified by | |
9ece6444 LB |
154 | <varname>RootImage=</varname>. Optionally a partition name can be prefixed, followed by colon, in |
155 | case the image has multiple partitions, otherwise partition name <literal>root</literal> is implied. | |
18d73705 | 156 | Options for multiple partitions can be specified in a single line with space separators. Assigning an empty |
9ece6444 | 157 | string removes previous assignments. Duplicated options are ignored. For a list of valid mount options, please |
21556381 ZJS |
158 | refer to |
159 | <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>. | |
160 | </para> | |
9ece6444 LB |
161 | |
162 | <para>Valid partition names follow the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable | |
163 | Partitions Specification</ulink>.</para> | |
164 | ||
165 | <table> | |
166 | <title>Accepted partition names</title> | |
167 | ||
168 | <tgroup cols='1'> | |
169 | <colspec colname='partition' /> | |
170 | <thead> | |
171 | <row> | |
172 | <entry>Partition Name</entry> | |
173 | </row> | |
174 | </thead> | |
175 | <tbody> | |
176 | <row> | |
177 | <entry>root</entry> | |
178 | </row> | |
179 | <row> | |
180 | <entry>root-secondary</entry> | |
181 | </row> | |
182 | <row> | |
183 | <entry>home</entry> | |
184 | </row> | |
185 | <row> | |
186 | <entry>srv</entry> | |
187 | </row> | |
188 | <row> | |
189 | <entry>esp</entry> | |
190 | </row> | |
191 | <row> | |
192 | <entry>xbootldr</entry> | |
193 | </row> | |
194 | <row> | |
195 | <entry>tmp</entry> | |
196 | </row> | |
197 | <row> | |
198 | <entry>var</entry> | |
199 | </row> | |
329cde79 LP |
200 | <row> |
201 | <entry>usr</entry> | |
202 | </row> | |
9ece6444 LB |
203 | </tbody> |
204 | </tgroup> | |
205 | </table> | |
18d73705 LB |
206 | |
207 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
208 | </varlistentry> | |
209 | ||
0389f4fa LB |
210 | <varlistentry> |
211 | <term><varname>RootHash=</varname></term> | |
212 | ||
213 | <listitem><para>Takes a data integrity (dm-verity) root hash specified in hexadecimal, or the path to a file | |
214 | containing a root hash in ASCII hexadecimal format. This option enables data integrity checks using dm-verity, | |
215 | if the used image contains the appropriate integrity data (see above) or if <varname>RootVerity=</varname> is used. | |
216 | The specified hash must match the root hash of integrity data, and is usually at least 256 bits (and hence 64 | |
217 | formatted hexadecimal characters) long (in case of SHA256 for example). If this option is not specified, but | |
218 | the image file carries the <literal>user.verity.roothash</literal> extended file attribute (see <citerefentry | |
219 | project='man-pages'><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry>), then the root | |
220 | hash is read from it, also as formatted hexadecimal characters. If the extended file attribute is not found (or | |
221 | is not supported by the underlying file system), but a file with the <filename>.roothash</filename> suffix is | |
222 | found next to the image file, bearing otherwise the same name (except if the image has the | |
223 | <filename>.raw</filename> suffix, in which case the root hash file must not have it in its name), the root hash | |
224 | is read from it and automatically used, also as formatted hexadecimal characters.</para> | |
225 | ||
329cde79 LP |
226 | <para>If the disk image contains a separate <filename>/usr/</filename> partition it may also be |
227 | Verity protected, in which case the root hash may configured via an extended attribute | |
228 | <literal>user.verity.usrhash</literal> or a <filename>.usrhash</filename> file adjacent to the disk | |
229 | image. There's currently no option to configure the root hash for the <filename>/usr/</filename> file | |
230 | system via the unit file directly.</para> | |
231 | ||
0389f4fa LB |
232 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> |
233 | </varlistentry> | |
234 | ||
d4d55b0d LB |
235 | <varlistentry> |
236 | <term><varname>RootHashSignature=</varname></term> | |
237 | ||
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238 | <listitem><para>Takes a PKCS7 signature of the <varname>RootHash=</varname> option as a path to a |
239 | DER-encoded signature file, or as an ASCII base64 string encoding of a DER-encoded signature prefixed | |
240 | by <literal>base64:</literal>. The dm-verity volume will only be opened if the signature of the root | |
241 | hash is valid and signed by a public key present in the kernel keyring. If this option is not | |
242 | specified, but a file with the <filename>.roothash.p7s</filename> suffix is found next to the image | |
243 | file, bearing otherwise the same name (except if the image has the <filename>.raw</filename> suffix, | |
244 | in which case the signature file must not have it in its name), the signature is read from it and | |
245 | automatically used.</para> | |
d4d55b0d | 246 | |
329cde79 LP |
247 | <para>If the disk image contains a separate <filename>/usr/</filename> partition it may also be |
248 | Verity protected, in which case the signature for the root hash may configured via a | |
249 | <filename>.usrhash.p7s</filename> file adjacent to the disk image. There's currently no option to | |
250 | configure the root hash signature for the <filename>/usr/</filename> via the unit file | |
251 | directly.</para> | |
252 | ||
d4d55b0d LB |
253 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> |
254 | </varlistentry> | |
255 | ||
0389f4fa LB |
256 | <varlistentry> |
257 | <term><varname>RootVerity=</varname></term> | |
258 | ||
259 | <listitem><para>Takes the path to a data integrity (dm-verity) file. This option enables data integrity checks | |
260 | using dm-verity, if <varname>RootImage=</varname> is used and a root-hash is passed and if the used image itself | |
261 | does not contains the integrity data. The integrity data must be matched by the root hash. If this option is not | |
262 | specified, but a file with the <filename>.verity</filename> suffix is found next to the image file, bearing otherwise | |
263 | the same name (except if the image has the <filename>.raw</filename> suffix, in which case the verity data file must | |
264 | not have it in its name), the verity data is read from it and automatically used.</para> | |
265 | ||
6b222c4b LP |
266 | <para>This option is supported only for disk images that contain a single file system, without an |
267 | enveloping partition table. Images that contain a GPT partition table should instead include both | |
268 | root file system and matching Verity data in the same image, implementing the <ulink | |
269 | url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partition Specification</ulink>.</para> | |
0389f4fa LB |
270 | |
271 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
272 | </varlistentry> | |
273 | ||
5d997827 LP |
274 | <varlistentry> |
275 | <term><varname>MountAPIVFS=</varname></term> | |
276 | ||
277 | <listitem><para>Takes a boolean argument. If on, a private mount namespace for the unit's processes is created | |
3b121157 | 278 | and the API file systems <filename>/proc/</filename>, <filename>/sys/</filename>, and <filename>/dev/</filename> |
ef3116b5 ZJS |
279 | are mounted inside of it, unless they are already mounted. Note that this option has no effect unless used in |
280 | conjunction with <varname>RootDirectory=</varname>/<varname>RootImage=</varname> as these three mounts are | |
281 | generally mounted in the host anyway, and unless the root directory is changed, the private mount namespace | |
3b121157 | 282 | will be a 1:1 copy of the host's, and include these three mounts. Note that the <filename>/dev/</filename> file |
ef3116b5 ZJS |
283 | system of the host is bind mounted if this option is used without <varname>PrivateDevices=</varname>. To run |
284 | the service with a private, minimal version of <filename>/dev/</filename>, combine this option with | |
c4d4b5a7 LP |
285 | <varname>PrivateDevices=</varname>.</para> |
286 | ||
287 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
288 | </varlistentry> |
289 | ||
a54342b3 LP |
290 | <varlistentry> |
291 | <term><varname>ProtectProc=</varname></term> | |
292 | ||
293 | <listitem><para>Takes one of <literal>noaccess</literal>, <literal>invisible</literal>, | |
294 | <literal>ptraceable</literal> or <literal>default</literal> (which it defaults to). When set, this | |
295 | controls the <literal>hidepid=</literal> mount option of the <literal>procfs</literal> instance for | |
296 | the unit that controls which directories with process metainformation | |
297 | (<filename>/proc/<replaceable>PID</replaceable></filename>) are visible and accessible: when set to | |
298 | <literal>noaccess</literal> the ability to access most of other users' process metadata in | |
299 | <filename>/proc/</filename> is taken away for processes of the service. When set to | |
300 | <literal>invisible</literal> processes owned by other users are hidden from | |
301 | <filename>/proc/</filename>. If <literal>ptraceable</literal> all processes that cannot be | |
302 | <function>ptrace()</function>'ed by a process are hidden to it. If <literal>default</literal> no | |
303 | restrictions on <filename>/proc/</filename> access or visibility are made. For further details see | |
304 | <ulink url="https://www.kernel.org/doc/html/latest/filesystems/proc.html#mount-options">The /proc | |
305 | Filesystem</ulink>. It is generally recommended to run most system services with this option set to | |
306 | <literal>invisible</literal>. This option is implemented via file system namespacing, and thus cannot | |
307 | be used with services that shall be able to install mount points in the host file system | |
308 | hierarchy. It also cannot be used for services that need to access metainformation about other users' | |
309 | processes. This option implies <varname>MountAPIVFS=</varname>.</para> | |
310 | ||
311 | <para>If the kernel doesn't support per-mount point <option>hidepid=</option> mount options this | |
312 | setting remains without effect, and the unit's processes will be able to access and see other process | |
313 | as if the option was not used.</para> | |
314 | ||
315 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
316 | </varlistentry> | |
317 | ||
318 | <varlistentry> | |
319 | <term><varname>ProcSubset=</varname></term> | |
320 | ||
321 | <listitem><para>Takes one of <literal>all</literal> (the default) and <literal>pid</literal>. If | |
322 | the latter all files and directories not directly associated with process management and introspection | |
323 | are made invisible in the <filename>/proc/</filename> file system configured for the unit's | |
324 | processes. This controls the <literal>subset=</literal> mount option of the <literal>procfs</literal> | |
325 | instance for the unit. For further details see <ulink | |
326 | url="https://www.kernel.org/doc/html/latest/filesystems/proc.html#mount-options">The /proc | |
327 | Filesystem</ulink>. Note that Linux exposes various kernel APIs via <filename>/proc/</filename>, | |
328 | which are made unavailable with this setting. Since these APIs are used frequently this option is | |
329 | useful only in a few, specific cases, and is not suitable for most non-trivial programs.</para> | |
330 | ||
331 | <para>Much like <varname>ProtectProc=</varname> above, this is implemented via file system mount | |
332 | namespacing, and hence the same restrictions apply: it is only available to system services, it | |
333 | disables mount propagation to the host mount table, and it implies | |
334 | <varname>MountAPIVFS=</varname>. Also, like <varname>ProtectProc=</varname> this setting is gracefully | |
335 | disabled if the used kernel does not support the <literal>subset=</literal> mount option of | |
336 | <literal>procfs</literal>.</para></listitem> | |
337 | </varlistentry> | |
338 | ||
b8afec21 LP |
339 | <varlistentry> |
340 | <term><varname>BindPaths=</varname></term> | |
341 | <term><varname>BindReadOnlyPaths=</varname></term> | |
342 | ||
343 | <listitem><para>Configures unit-specific bind mounts. A bind mount makes a particular file or directory | |
344 | available at an additional place in the unit's view of the file system. Any bind mounts created with this | |
345 | option are specific to the unit, and are not visible in the host's mount table. This option expects a | |
346 | whitespace separated list of bind mount definitions. Each definition consists of a colon-separated triple of | |
347 | source path, destination path and option string, where the latter two are optional. If only a source path is | |
348 | specified the source and destination is taken to be the same. The option string may be either | |
349 | <literal>rbind</literal> or <literal>norbind</literal> for configuring a recursive or non-recursive bind | |
4ca763a9 YW |
350 | mount. If the destination path is omitted, the option string must be omitted too. |
351 | Each bind mount definition may be prefixed with <literal>-</literal>, in which case it will be ignored | |
352 | when its source path does not exist.</para> | |
b8afec21 LP |
353 | |
354 | <para><varname>BindPaths=</varname> creates regular writable bind mounts (unless the source file system mount | |
355 | is already marked read-only), while <varname>BindReadOnlyPaths=</varname> creates read-only bind mounts. These | |
356 | settings may be used more than once, each usage appends to the unit's list of bind mounts. If the empty string | |
357 | is assigned to either of these two options the entire list of bind mounts defined prior to this is reset. Note | |
358 | that in this case both read-only and regular bind mounts are reset, regardless which of the two settings is | |
359 | used.</para> | |
360 | ||
361 | <para>This option is particularly useful when <varname>RootDirectory=</varname>/<varname>RootImage=</varname> | |
362 | is used. In this case the source path refers to a path on the host file system, while the destination path | |
c4d4b5a7 LP |
363 | refers to a path below the root directory of the unit.</para> |
364 | ||
db8d154d ZJS |
365 | <para>Note that the destination directory must exist or systemd must be able to create it. Thus, it |
366 | is not possible to use those options for mount points nested underneath paths specified in | |
367 | <varname>InaccessiblePaths=</varname>, or under <filename>/home/</filename> and other protected | |
368 | directories if <varname>ProtectHome=yes</varname> is | |
369 | specified. <varname>TemporaryFileSystem=</varname> with <literal>:ro</literal> or | |
370 | <varname>ProtectHome=tmpfs</varname> should be used instead.</para> | |
371 | ||
c4d4b5a7 | 372 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> |
b8afec21 LP |
373 | </varlistentry> |
374 | ||
b3d13314 LB |
375 | <varlistentry> |
376 | <term><varname>MountImages=</varname></term> | |
377 | ||
378 | <listitem><para>This setting is similar to <varname>RootImage=</varname> in that it mounts a file | |
379 | system hierarchy from a block device node or loopback file, but the destination directory can be | |
380 | specified as well as mount options. This option expects a whitespace separated list of mount | |
381 | definitions. Each definition consists of a colon-separated tuple of source path and destination | |
427353f6 LB |
382 | definitions, optionally followed by another colon and a list of mount options.</para> |
383 | ||
384 | <para>Mount options may be defined as a single comma-separated list of options, in which case they | |
385 | will be implicitly applied to the root partition on the image, or a series of colon-separated tuples | |
386 | of partition name and mount options. Valid partition names and mount options are the same as for | |
387 | <varname>RootImageOptions=</varname> setting described above.</para> | |
388 | ||
389 | <para>Each mount definition may be prefixed with <literal>-</literal>, in which case it will be | |
b3d13314 LB |
390 | ignored when its source path does not exist. The source argument is a path to a block device node or |
391 | regular file. If source or destination contain a <literal>:</literal>, it needs to be escaped as | |
427353f6 LB |
392 | <literal>\:</literal>. The device node or file system image file needs to follow the same rules as |
393 | specified for <varname>RootImage=</varname>. Any mounts created with this option are specific to the | |
394 | unit, and are not visible in the host's mount table.</para> | |
b3d13314 LB |
395 | |
396 | <para>These settings may be used more than once, each usage appends to the unit's list of mount | |
397 | paths. If the empty string is assigned, the entire list of mount paths defined prior to this is | |
398 | reset.</para> | |
399 | ||
400 | <para>Note that the destination directory must exist or systemd must be able to create it. Thus, it | |
401 | is not possible to use those options for mount points nested underneath paths specified in | |
402 | <varname>InaccessiblePaths=</varname>, or under <filename>/home/</filename> and other protected | |
403 | directories if <varname>ProtectHome=yes</varname> is specified.</para> | |
404 | ||
405 | <para>When <varname>DevicePolicy=</varname> is set to <literal>closed</literal> or | |
406 | <literal>strict</literal>, or set to <literal>auto</literal> and <varname>DeviceAllow=</varname> is | |
407 | set, then this setting adds <filename>/dev/loop-control</filename> with <constant>rw</constant> mode, | |
408 | <literal>block-loop</literal> and <literal>block-blkext</literal> with <constant>rwm</constant> mode | |
409 | to <varname>DeviceAllow=</varname>. See | |
410 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
411 | for the details about <varname>DevicePolicy=</varname> or <varname>DeviceAllow=</varname>. Also, see | |
412 | <varname>PrivateDevices=</varname> below, as it may change the setting of | |
413 | <varname>DevicePolicy=</varname>.</para> | |
414 | ||
415 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
416 | </varlistentry> | |
b8afec21 LP |
417 | </variablelist> |
418 | </refsect1> | |
419 | ||
420 | <refsect1> | |
421 | <title>Credentials</title> | |
422 | ||
c4d4b5a7 LP |
423 | <xi:include href="system-only.xml" xpointer="plural"/> |
424 | ||
b8afec21 LP |
425 | <variablelist class='unit-directives'> |
426 | ||
798d3a52 ZJS |
427 | <varlistentry> |
428 | <term><varname>User=</varname></term> | |
429 | <term><varname>Group=</varname></term> | |
430 | ||
29206d46 | 431 | <listitem><para>Set the UNIX user or group that the processes are executed as, respectively. Takes a single |
b8afec21 LP |
432 | user or group name, or a numeric ID as argument. For system services (services run by the system service |
433 | manager, i.e. managed by PID 1) and for user services of the root user (services managed by root's instance of | |
47da760e LP |
434 | <command>systemd --user</command>), the default is <literal>root</literal>, but <varname>User=</varname> may be |
435 | used to specify a different user. For user services of any other user, switching user identity is not | |
436 | permitted, hence the only valid setting is the same user the user's service manager is running as. If no group | |
437 | is set, the default group of the user is used. This setting does not affect commands whose command line is | |
565dab8e LP |
438 | prefixed with <literal>+</literal>.</para> |
439 | ||
887a8fa3 LP |
440 | <para>Note that this enforces only weak restrictions on the user/group name syntax, but will generate |
441 | warnings in many cases where user/group names do not adhere to the following rules: the specified | |
442 | name should consist only of the characters a-z, A-Z, 0-9, <literal>_</literal> and | |
443 | <literal>-</literal>, except for the first character which must be one of a-z, A-Z and | |
444 | <literal>_</literal> (i.e. digits and <literal>-</literal> are not permitted as first character). The | |
445 | user/group name must have at least one character, and at most 31. These restrictions are made in | |
446 | order to avoid ambiguities and to ensure user/group names and unit files remain portable among Linux | |
447 | systems. For further details on the names accepted and the names warned about see <ulink | |
448 | url="https://systemd.io/USER_NAMES">User/Group Name Syntax</ulink>.</para> | |
565dab8e LP |
449 | |
450 | <para>When used in conjunction with <varname>DynamicUser=</varname> the user/group name specified is | |
ba96a8a2 LP |
451 | dynamically allocated at the time the service is started, and released at the time the service is |
452 | stopped — unless it is already allocated statically (see below). If <varname>DynamicUser=</varname> | |
453 | is not used the specified user and group must have been created statically in the user database no | |
454 | later than the moment the service is started, for example using the | |
455 | <citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
456 | facility, which is applied at boot or package install time. If the user does not exist by then | |
457 | program invocation will fail.</para> | |
b042dd68 LP |
458 | |
459 | <para>If the <varname>User=</varname> setting is used the supplementary group list is initialized | |
460 | from the specified user's default group list, as defined in the system's user and group | |
461 | database. Additional groups may be configured through the <varname>SupplementaryGroups=</varname> | |
462 | setting (see below).</para></listitem> | |
29206d46 LP |
463 | </varlistentry> |
464 | ||
465 | <varlistentry> | |
466 | <term><varname>DynamicUser=</varname></term> | |
467 | ||
c648d4d4 LP |
468 | <listitem><para>Takes a boolean parameter. If set, a UNIX user and group pair is allocated |
469 | dynamically when the unit is started, and released as soon as it is stopped. The user and group will | |
470 | not be added to <filename>/etc/passwd</filename> or <filename>/etc/group</filename>, but are managed | |
471 | transiently during runtime. The | |
472 | <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> glibc | |
473 | NSS module provides integration of these dynamic users/groups into the system's user and group | |
29206d46 | 474 | databases. The user and group name to use may be configured via <varname>User=</varname> and |
c648d4d4 LP |
475 | <varname>Group=</varname> (see above). If these options are not used and dynamic user/group |
476 | allocation is enabled for a unit, the name of the dynamic user/group is implicitly derived from the | |
477 | unit name. If the unit name without the type suffix qualifies as valid user name it is used directly, | |
478 | otherwise a name incorporating a hash of it is used. If a statically allocated user or group of the | |
479 | configured name already exists, it is used and no dynamic user/group is allocated. Note that if | |
480 | <varname>User=</varname> is specified and the static group with the name exists, then it is required | |
481 | that the static user with the name already exists. Similarly, if <varname>Group=</varname> is | |
482 | specified and the static user with the name exists, then it is required that the static group with | |
483 | the name already exists. Dynamic users/groups are allocated from the UID/GID range 61184…65519. It is | |
484 | recommended to avoid this range for regular system or login users. At any point in time each UID/GID | |
485 | from this range is only assigned to zero or one dynamically allocated users/groups in use. However, | |
486 | UID/GIDs are recycled after a unit is terminated. Care should be taken that any processes running as | |
487 | part of a unit for which dynamic users/groups are enabled do not leave files or directories owned by | |
488 | these users/groups around, as a different unit might get the same UID/GID assigned later on, and thus | |
489 | gain access to these files or directories. If <varname>DynamicUser=</varname> is enabled, | |
e0e65f7d LP |
490 | <varname>RemoveIPC=</varname> and <varname>PrivateTmp=</varname> are implied (and cannot be turned |
491 | off). This ensures that the lifetime of IPC objects and temporary files created by the executed | |
492 | processes is bound to the runtime of the service, and hence the lifetime of the dynamic | |
493 | user/group. Since <filename>/tmp/</filename> and <filename>/var/tmp/</filename> are usually the only | |
494 | world-writable directories on a system this ensures that a unit making use of dynamic user/group | |
495 | allocation cannot leave files around after unit termination. Furthermore | |
496 | <varname>NoNewPrivileges=</varname> and <varname>RestrictSUIDSGID=</varname> are implicitly enabled | |
497 | (and cannot be disabled), to ensure that processes invoked cannot take benefit or create SUID/SGID | |
498 | files or directories. Moreover <varname>ProtectSystem=strict</varname> and | |
c648d4d4 LP |
499 | <varname>ProtectHome=read-only</varname> are implied, thus prohibiting the service to write to |
500 | arbitrary file system locations. In order to allow the service to write to certain directories, they | |
6b000af4 | 501 | have to be allow-listed using <varname>ReadWritePaths=</varname>, but care must be taken so that |
c648d4d4 LP |
502 | UID/GID recycling doesn't create security issues involving files created by the service. Use |
503 | <varname>RuntimeDirectory=</varname> (see below) in order to assign a writable runtime directory to a | |
504 | service, owned by the dynamic user/group and removed automatically when the unit is terminated. Use | |
505 | <varname>StateDirectory=</varname>, <varname>CacheDirectory=</varname> and | |
506 | <varname>LogsDirectory=</varname> in order to assign a set of writable directories for specific | |
507 | purposes to the service in a way that they are protected from vulnerabilities due to UID reuse (see | |
508 | below). If this option is enabled, care should be taken that the unit's processes do not get access | |
509 | to directories outside of these explicitly configured and managed ones. Specifically, do not use | |
510 | <varname>BindPaths=</varname> and be careful with <constant>AF_UNIX</constant> file descriptor | |
511 | passing for directory file descriptors, as this would permit processes to create files or directories | |
de04bbdc | 512 | owned by the dynamic user/group that are not subject to the lifecycle and access guarantees of the |
c648d4d4 | 513 | service. Defaults to off.</para></listitem> |
798d3a52 ZJS |
514 | </varlistentry> |
515 | ||
516 | <varlistentry> | |
517 | <term><varname>SupplementaryGroups=</varname></term> | |
518 | ||
b8afec21 LP |
519 | <listitem><para>Sets the supplementary Unix groups the processes are executed as. This takes a space-separated |
520 | list of group names or IDs. This option may be specified more than once, in which case all listed groups are | |
521 | set as supplementary groups. When the empty string is assigned, the list of supplementary groups is reset, and | |
522 | all assignments prior to this one will have no effect. In any way, this option does not override, but extends | |
523 | the list of supplementary groups configured in the system group database for the user. This does not affect | |
524 | commands prefixed with <literal>+</literal>.</para></listitem> | |
798d3a52 ZJS |
525 | </varlistentry> |
526 | ||
00d9ef85 | 527 | <varlistentry> |
b8afec21 | 528 | <term><varname>PAMName=</varname></term> |
00d9ef85 | 529 | |
b8afec21 LP |
530 | <listitem><para>Sets the PAM service name to set up a session as. If set, the executed process will be |
531 | registered as a PAM session under the specified service name. This is only useful in conjunction with the | |
532 | <varname>User=</varname> setting, and is otherwise ignored. If not set, no PAM session will be opened for the | |
533 | executed processes. See <citerefentry | |
534 | project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry> for | |
535 | details.</para> | |
00d9ef85 | 536 | |
b8afec21 LP |
537 | <para>Note that for each unit making use of this option a PAM session handler process will be maintained as |
538 | part of the unit and stays around as long as the unit is active, to ensure that appropriate actions can be | |
539 | taken when the unit and hence the PAM session terminates. This process is named <literal>(sd-pam)</literal> and | |
540 | is an immediate child process of the unit's main process.</para> | |
798d3a52 | 541 | |
b8afec21 LP |
542 | <para>Note that when this option is used for a unit it is very likely (depending on PAM configuration) that the |
543 | main unit process will be migrated to its own session scope unit when it is activated. This process will hence | |
544 | be associated with two units: the unit it was originally started from (and for which | |
545 | <varname>PAMName=</varname> was configured), and the session scope unit. Any child processes of that process | |
546 | will however be associated with the session scope unit only. This has implications when used in combination | |
547 | with <varname>NotifyAccess=</varname><option>all</option>, as these child processes will not be able to affect | |
548 | changes in the original unit through notification messages. These messages will be considered belonging to the | |
549 | session scope unit and not the original unit. It is hence not recommended to use <varname>PAMName=</varname> in | |
550 | combination with <varname>NotifyAccess=</varname><option>all</option>.</para> | |
551 | </listitem> | |
798d3a52 ZJS |
552 | </varlistentry> |
553 | ||
b8afec21 LP |
554 | </variablelist> |
555 | </refsect1> | |
798d3a52 | 556 | |
b8afec21 LP |
557 | <refsect1> |
558 | <title>Capabilities</title> | |
798d3a52 | 559 | |
c4d4b5a7 LP |
560 | <xi:include href="system-only.xml" xpointer="plural"/> |
561 | ||
b8afec21 | 562 | <variablelist class='unit-directives'> |
798d3a52 ZJS |
563 | |
564 | <varlistentry> | |
b8afec21 LP |
565 | <term><varname>CapabilityBoundingSet=</varname></term> |
566 | ||
b2af819b LP |
567 | <listitem><para>Controls which capabilities to include in the capability bounding set for the |
568 | executed process. See <citerefentry | |
569 | project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
570 | for details. Takes a whitespace-separated list of capability names, | |
571 | e.g. <constant>CAP_SYS_ADMIN</constant>, <constant>CAP_DAC_OVERRIDE</constant>, | |
572 | <constant>CAP_SYS_PTRACE</constant>. Capabilities listed will be included in the bounding set, all | |
573 | others are removed. If the list of capabilities is prefixed with <literal>~</literal>, all but the | |
574 | listed capabilities will be included, the effect of the assignment inverted. Note that this option | |
575 | also affects the respective capabilities in the effective, permitted and inheritable capability | |
576 | sets. If this option is not used, the capability bounding set is not modified on process execution, | |
577 | hence no limits on the capabilities of the process are enforced. This option may appear more than | |
578 | once, in which case the bounding sets are merged by <constant>OR</constant>, or by | |
579 | <constant>AND</constant> if the lines are prefixed with <literal>~</literal> (see below). If the | |
580 | empty string is assigned to this option, the bounding set is reset to the empty capability set, and | |
581 | all prior settings have no effect. If set to <literal>~</literal> (without any further argument), | |
582 | the bounding set is reset to the full set of available capabilities, also undoing any previous | |
583 | settings. This does not affect commands prefixed with <literal>+</literal>.</para> | |
584 | ||
585 | <para>Use | |
586 | <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s | |
587 | <command>capability</command> command to retrieve a list of capabilities defined on the local | |
588 | system.</para> | |
798d3a52 | 589 | |
b8afec21 LP |
590 | <para>Example: if a unit has the following, |
591 | <programlisting>CapabilityBoundingSet=CAP_A CAP_B | |
592 | CapabilityBoundingSet=CAP_B CAP_C</programlisting> | |
f8b68539 ZJS |
593 | then <constant index='false'>CAP_A</constant>, <constant index='false'>CAP_B</constant>, and |
594 | <constant index='false'>CAP_C</constant> are set. If the second line is prefixed with | |
595 | <literal>~</literal>, e.g., | |
b8afec21 LP |
596 | <programlisting>CapabilityBoundingSet=CAP_A CAP_B |
597 | CapabilityBoundingSet=~CAP_B CAP_C</programlisting> | |
f8b68539 | 598 | then, only <constant index='false'>CAP_A</constant> is set.</para></listitem> |
798d3a52 ZJS |
599 | </varlistentry> |
600 | ||
601 | <varlistentry> | |
b8afec21 | 602 | <term><varname>AmbientCapabilities=</varname></term> |
798d3a52 | 603 | |
b8afec21 LP |
604 | <listitem><para>Controls which capabilities to include in the ambient capability set for the executed |
605 | process. Takes a whitespace-separated list of capability names, e.g. <constant>CAP_SYS_ADMIN</constant>, | |
606 | <constant>CAP_DAC_OVERRIDE</constant>, <constant>CAP_SYS_PTRACE</constant>. This option may appear more than | |
607 | once in which case the ambient capability sets are merged (see the above examples in | |
608 | <varname>CapabilityBoundingSet=</varname>). If the list of capabilities is prefixed with <literal>~</literal>, | |
609 | all but the listed capabilities will be included, the effect of the assignment inverted. If the empty string is | |
610 | assigned to this option, the ambient capability set is reset to the empty capability set, and all prior | |
611 | settings have no effect. If set to <literal>~</literal> (without any further argument), the ambient capability | |
612 | set is reset to the full set of available capabilities, also undoing any previous settings. Note that adding | |
613 | capabilities to ambient capability set adds them to the process's inherited capability set. </para><para> | |
614 | Ambient capability sets are useful if you want to execute a process as a non-privileged user but still want to | |
615 | give it some capabilities. Note that in this case option <constant>keep-caps</constant> is automatically added | |
616 | to <varname>SecureBits=</varname> to retain the capabilities over the user | |
617 | change. <varname>AmbientCapabilities=</varname> does not affect commands prefixed with | |
618 | <literal>+</literal>.</para></listitem> | |
798d3a52 ZJS |
619 | </varlistentry> |
620 | ||
b8afec21 LP |
621 | </variablelist> |
622 | </refsect1> | |
798d3a52 | 623 | |
b8afec21 LP |
624 | <refsect1> |
625 | <title>Security</title> | |
798d3a52 | 626 | |
b8afec21 | 627 | <variablelist class='unit-directives'> |
798d3a52 ZJS |
628 | |
629 | <varlistentry> | |
b8afec21 | 630 | <term><varname>NoNewPrivileges=</varname></term> |
798d3a52 | 631 | |
7445db6e LP |
632 | <listitem><para>Takes a boolean argument. If true, ensures that the service process and all its |
633 | children can never gain new privileges through <function>execve()</function> (e.g. via setuid or | |
634 | setgid bits, or filesystem capabilities). This is the simplest and most effective way to ensure that | |
635 | a process and its children can never elevate privileges again. Defaults to false, but certain | |
636 | settings override this and ignore the value of this setting. This is the case when | |
637 | <varname>SystemCallFilter=</varname>, <varname>SystemCallArchitectures=</varname>, | |
638 | <varname>RestrictAddressFamilies=</varname>, <varname>RestrictNamespaces=</varname>, | |
639 | <varname>PrivateDevices=</varname>, <varname>ProtectKernelTunables=</varname>, | |
d916e35b | 640 | <varname>ProtectKernelModules=</varname>, <varname>ProtectKernelLogs=</varname>, |
022d3345 KK |
641 | <varname>ProtectClock=</varname>, <varname>MemoryDenyWriteExecute=</varname>, |
642 | <varname>RestrictRealtime=</varname>, <varname>RestrictSUIDSGID=</varname>, <varname>DynamicUser=</varname> | |
643 | or <varname>LockPersonality=</varname> are specified. Note that even if this setting is overridden by them, | |
644 | <command>systemctl show</command> shows the original value of this setting. | |
645 | Also see <ulink url="https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html">No New Privileges | |
bf65b7e0 | 646 | Flag</ulink>.</para></listitem> |
798d3a52 ZJS |
647 | </varlistentry> |
648 | ||
649 | <varlistentry> | |
b8afec21 | 650 | <term><varname>SecureBits=</varname></term> |
798d3a52 | 651 | |
b8afec21 LP |
652 | <listitem><para>Controls the secure bits set for the executed process. Takes a space-separated combination of |
653 | options from the following list: <option>keep-caps</option>, <option>keep-caps-locked</option>, | |
654 | <option>no-setuid-fixup</option>, <option>no-setuid-fixup-locked</option>, <option>noroot</option>, and | |
655 | <option>noroot-locked</option>. This option may appear more than once, in which case the secure bits are | |
656 | ORed. If the empty string is assigned to this option, the bits are reset to 0. This does not affect commands | |
657 | prefixed with <literal>+</literal>. See <citerefentry | |
658 | project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
659 | details.</para></listitem> | |
798d3a52 ZJS |
660 | </varlistentry> |
661 | ||
b8afec21 LP |
662 | </variablelist> |
663 | </refsect1> | |
798d3a52 | 664 | |
b8afec21 LP |
665 | <refsect1> |
666 | <title>Mandatory Access Control</title> | |
c4d4b5a7 LP |
667 | |
668 | <xi:include href="system-only.xml" xpointer="plural"/> | |
669 | ||
e0e2ecd5 | 670 | <variablelist class='unit-directives'> |
798d3a52 | 671 | |
798d3a52 | 672 | <varlistentry> |
b8afec21 LP |
673 | <term><varname>SELinuxContext=</varname></term> |
674 | ||
675 | <listitem><para>Set the SELinux security context of the executed process. If set, this will override the | |
676 | automated domain transition. However, the policy still needs to authorize the transition. This directive is | |
677 | ignored if SELinux is disabled. If prefixed by <literal>-</literal>, all errors will be ignored. This does not | |
678 | affect commands prefixed with <literal>+</literal>. See <citerefentry | |
679 | project='die-net'><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
680 | details.</para></listitem> | |
798d3a52 ZJS |
681 | </varlistentry> |
682 | ||
b4c14404 | 683 | <varlistentry> |
b8afec21 | 684 | <term><varname>AppArmorProfile=</varname></term> |
b4c14404 | 685 | |
e9dd6984 ZJS |
686 | <listitem><para>Takes a profile name as argument. The process executed by the unit will switch to |
687 | this profile when started. Profiles must already be loaded in the kernel, or the unit will fail. If | |
688 | prefixed by <literal>-</literal>, all errors will be ignored. This setting has no effect if AppArmor | |
885a4e6c | 689 | is not enabled. This setting does not affect commands prefixed with <literal>+</literal>.</para> |
e9dd6984 | 690 | </listitem> |
b8afec21 | 691 | </varlistentry> |
00819cc1 | 692 | |
b8afec21 LP |
693 | <varlistentry> |
694 | <term><varname>SmackProcessLabel=</varname></term> | |
b4c14404 | 695 | |
b8afec21 LP |
696 | <listitem><para>Takes a <option>SMACK64</option> security label as argument. The process executed by the unit |
697 | will be started under this label and SMACK will decide whether the process is allowed to run or not, based on | |
698 | it. The process will continue to run under the label specified here unless the executable has its own | |
699 | <option>SMACK64EXEC</option> label, in which case the process will transition to run under that label. When not | |
700 | specified, the label that systemd is running under is used. This directive is ignored if SMACK is | |
701 | disabled.</para> | |
b4c14404 | 702 | |
b8afec21 LP |
703 | <para>The value may be prefixed by <literal>-</literal>, in which case all errors will be ignored. An empty |
704 | value may be specified to unset previous assignments. This does not affect commands prefixed with | |
705 | <literal>+</literal>.</para></listitem> | |
b4c14404 FB |
706 | </varlistentry> |
707 | ||
b8afec21 LP |
708 | </variablelist> |
709 | </refsect1> | |
00819cc1 | 710 | |
b8afec21 LP |
711 | <refsect1> |
712 | <title>Process Properties</title> | |
00819cc1 | 713 | |
e0e2ecd5 | 714 | <variablelist class='unit-directives'> |
00819cc1 | 715 | |
798d3a52 | 716 | <varlistentry> |
b8afec21 LP |
717 | <term><varname>LimitCPU=</varname></term> |
718 | <term><varname>LimitFSIZE=</varname></term> | |
719 | <term><varname>LimitDATA=</varname></term> | |
720 | <term><varname>LimitSTACK=</varname></term> | |
721 | <term><varname>LimitCORE=</varname></term> | |
722 | <term><varname>LimitRSS=</varname></term> | |
723 | <term><varname>LimitNOFILE=</varname></term> | |
724 | <term><varname>LimitAS=</varname></term> | |
725 | <term><varname>LimitNPROC=</varname></term> | |
726 | <term><varname>LimitMEMLOCK=</varname></term> | |
727 | <term><varname>LimitLOCKS=</varname></term> | |
728 | <term><varname>LimitSIGPENDING=</varname></term> | |
729 | <term><varname>LimitMSGQUEUE=</varname></term> | |
730 | <term><varname>LimitNICE=</varname></term> | |
731 | <term><varname>LimitRTPRIO=</varname></term> | |
732 | <term><varname>LimitRTTIME=</varname></term> | |
fc8d0381 | 733 | |
b8afec21 | 734 | <listitem><para>Set soft and hard limits on various resources for executed processes. See |
54ed193f LP |
735 | <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
736 | details on the resource limit concept. Resource limits may be specified in two formats: either as | |
737 | single value to set a specific soft and hard limit to the same value, or as colon-separated pair | |
738 | <option>soft:hard</option> to set both limits individually (e.g. <literal>LimitAS=4G:16G</literal>). | |
739 | Use the string <option>infinity</option> to configure no limit on a specific resource. The | |
740 | multiplicative suffixes K, M, G, T, P and E (to the base 1024) may be used for resource limits | |
741 | measured in bytes (e.g. <literal>LimitAS=16G</literal>). For the limits referring to time values, the | |
742 | usual time units ms, s, min, h and so on may be used (see | |
b8afec21 | 743 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for |
54ed193f LP |
744 | details). Note that if no time unit is specified for <varname>LimitCPU=</varname> the default unit of |
745 | seconds is implied, while for <varname>LimitRTTIME=</varname> the default unit of microseconds is | |
746 | implied. Also, note that the effective granularity of the limits might influence their | |
747 | enforcement. For example, time limits specified for <varname>LimitCPU=</varname> will be rounded up | |
748 | implicitly to multiples of 1s. For <varname>LimitNICE=</varname> the value may be specified in two | |
749 | syntaxes: if prefixed with <literal>+</literal> or <literal>-</literal>, the value is understood as | |
750 | regular Linux nice value in the range -20..19. If not prefixed like this the value is understood as | |
751 | raw resource limit parameter in the range 0..40 (with 0 being equivalent to 1).</para> | |
752 | ||
753 | <para>Note that most process resource limits configured with these options are per-process, and | |
754 | processes may fork in order to acquire a new set of resources that are accounted independently of the | |
755 | original process, and may thus escape limits set. Also note that <varname>LimitRSS=</varname> is not | |
756 | implemented on Linux, and setting it has no effect. Often it is advisable to prefer the resource | |
757 | controls listed in | |
b8afec21 | 758 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
54ed193f LP |
759 | over these per-process limits, as they apply to services as a whole, may be altered dynamically at |
760 | runtime, and are generally more expressive. For example, <varname>MemoryMax=</varname> is a more | |
761 | powerful (and working) replacement for <varname>LimitRSS=</varname>.</para> | |
fc8d0381 | 762 | |
b8afec21 LP |
763 | <para>Resource limits not configured explicitly for a unit default to the value configured in the various |
764 | <varname>DefaultLimitCPU=</varname>, <varname>DefaultLimitFSIZE=</varname>, … options available in | |
765 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, and – | |
766 | if not configured there – the kernel or per-user defaults, as defined by the OS (the latter only for user | |
54ed193f LP |
767 | services, see below).</para> |
768 | ||
769 | <para>For system units these resource limits may be chosen freely. When these settings are configured | |
770 | in a user service (i.e. a service run by the per-user instance of the service manager) they cannot be | |
771 | used to raise the limits above those set for the user manager itself when it was first invoked, as | |
772 | the user's service manager generally lacks the privileges to do so. In user context these | |
773 | configuration options are hence only useful to lower the limits passed in or to raise the soft limit | |
774 | to the maximum of the hard limit as configured for the user. To raise the user's limits further, the | |
775 | available configuration mechanisms differ between operating systems, but typically require | |
776 | privileges. In most cases it is possible to configure higher per-user resource limits via PAM or by | |
777 | setting limits on the system service encapsulating the user's service manager, i.e. the user's | |
778 | instance of <filename>user@.service</filename>. After making such changes, make sure to restart the | |
779 | user's service manager.</para> | |
fc8d0381 | 780 | |
b8afec21 LP |
781 | <table> |
782 | <title>Resource limit directives, their equivalent <command>ulimit</command> shell commands and the unit used</title> | |
798d3a52 | 783 | |
a4c18002 | 784 | <tgroup cols='3'> |
798d3a52 ZJS |
785 | <colspec colname='directive' /> |
786 | <colspec colname='equivalent' /> | |
a4c18002 | 787 | <colspec colname='unit' /> |
798d3a52 ZJS |
788 | <thead> |
789 | <row> | |
790 | <entry>Directive</entry> | |
f4c9356d | 791 | <entry><command>ulimit</command> equivalent</entry> |
a4c18002 | 792 | <entry>Unit</entry> |
798d3a52 ZJS |
793 | </row> |
794 | </thead> | |
795 | <tbody> | |
796 | <row> | |
a4c18002 | 797 | <entry>LimitCPU=</entry> |
798d3a52 | 798 | <entry>ulimit -t</entry> |
a4c18002 | 799 | <entry>Seconds</entry> |
798d3a52 ZJS |
800 | </row> |
801 | <row> | |
a4c18002 | 802 | <entry>LimitFSIZE=</entry> |
798d3a52 | 803 | <entry>ulimit -f</entry> |
a4c18002 | 804 | <entry>Bytes</entry> |
798d3a52 ZJS |
805 | </row> |
806 | <row> | |
a4c18002 | 807 | <entry>LimitDATA=</entry> |
798d3a52 | 808 | <entry>ulimit -d</entry> |
a4c18002 | 809 | <entry>Bytes</entry> |
798d3a52 ZJS |
810 | </row> |
811 | <row> | |
a4c18002 | 812 | <entry>LimitSTACK=</entry> |
798d3a52 | 813 | <entry>ulimit -s</entry> |
a4c18002 | 814 | <entry>Bytes</entry> |
798d3a52 ZJS |
815 | </row> |
816 | <row> | |
a4c18002 | 817 | <entry>LimitCORE=</entry> |
798d3a52 | 818 | <entry>ulimit -c</entry> |
a4c18002 | 819 | <entry>Bytes</entry> |
798d3a52 ZJS |
820 | </row> |
821 | <row> | |
a4c18002 | 822 | <entry>LimitRSS=</entry> |
798d3a52 | 823 | <entry>ulimit -m</entry> |
a4c18002 | 824 | <entry>Bytes</entry> |
798d3a52 ZJS |
825 | </row> |
826 | <row> | |
a4c18002 | 827 | <entry>LimitNOFILE=</entry> |
798d3a52 | 828 | <entry>ulimit -n</entry> |
a4c18002 | 829 | <entry>Number of File Descriptors</entry> |
798d3a52 ZJS |
830 | </row> |
831 | <row> | |
a4c18002 | 832 | <entry>LimitAS=</entry> |
798d3a52 | 833 | <entry>ulimit -v</entry> |
a4c18002 | 834 | <entry>Bytes</entry> |
798d3a52 ZJS |
835 | </row> |
836 | <row> | |
a4c18002 | 837 | <entry>LimitNPROC=</entry> |
798d3a52 | 838 | <entry>ulimit -u</entry> |
a4c18002 | 839 | <entry>Number of Processes</entry> |
798d3a52 ZJS |
840 | </row> |
841 | <row> | |
a4c18002 | 842 | <entry>LimitMEMLOCK=</entry> |
798d3a52 | 843 | <entry>ulimit -l</entry> |
a4c18002 | 844 | <entry>Bytes</entry> |
798d3a52 ZJS |
845 | </row> |
846 | <row> | |
a4c18002 | 847 | <entry>LimitLOCKS=</entry> |
798d3a52 | 848 | <entry>ulimit -x</entry> |
a4c18002 | 849 | <entry>Number of Locks</entry> |
798d3a52 ZJS |
850 | </row> |
851 | <row> | |
a4c18002 | 852 | <entry>LimitSIGPENDING=</entry> |
798d3a52 | 853 | <entry>ulimit -i</entry> |
a4c18002 | 854 | <entry>Number of Queued Signals</entry> |
798d3a52 ZJS |
855 | </row> |
856 | <row> | |
a4c18002 | 857 | <entry>LimitMSGQUEUE=</entry> |
798d3a52 | 858 | <entry>ulimit -q</entry> |
a4c18002 | 859 | <entry>Bytes</entry> |
798d3a52 ZJS |
860 | </row> |
861 | <row> | |
a4c18002 | 862 | <entry>LimitNICE=</entry> |
798d3a52 | 863 | <entry>ulimit -e</entry> |
a4c18002 | 864 | <entry>Nice Level</entry> |
798d3a52 ZJS |
865 | </row> |
866 | <row> | |
a4c18002 | 867 | <entry>LimitRTPRIO=</entry> |
798d3a52 | 868 | <entry>ulimit -r</entry> |
a4c18002 | 869 | <entry>Realtime Priority</entry> |
798d3a52 ZJS |
870 | </row> |
871 | <row> | |
a4c18002 | 872 | <entry>LimitRTTIME=</entry> |
798d3a52 | 873 | <entry>No equivalent</entry> |
a4c18002 | 874 | <entry>Microseconds</entry> |
798d3a52 ZJS |
875 | </row> |
876 | </tbody> | |
877 | </tgroup> | |
a4c18002 | 878 | </table></listitem> |
798d3a52 ZJS |
879 | </varlistentry> |
880 | ||
881 | <varlistentry> | |
b8afec21 | 882 | <term><varname>UMask=</varname></term> |
9eb484fa | 883 | |
b8afec21 | 884 | <listitem><para>Controls the file mode creation mask. Takes an access mode in octal notation. See |
5e37d193 | 885 | <citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
60bcb459 LP |
886 | details. Defaults to 0022 for system units. For user units the default value is inherited from the |
887 | per-user service manager (whose default is in turn inherited from the system service manager, and | |
377a9545 | 888 | thus typically also is 0022 — unless overridden by a PAM module). In order to change the per-user mask |
60bcb459 LP |
889 | for all user services, consider setting the <varname>UMask=</varname> setting of the user's |
890 | <filename>user@.service</filename> system service instance. The per-user umask may also be set via | |
891 | the <varname>umask</varname> field of a user's <ulink url="https://systemd.io/USER_RECORD">JSON User | |
892 | Record</ulink> (for users managed by | |
893 | <citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
894 | this field may be controlled via <command>homectl --umask=</command>). It may also be set via a PAM | |
895 | module, such as <citerefentry | |
896 | project='man-pages'><refentrytitle>pam_umask</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem> | |
b8afec21 LP |
897 | </varlistentry> |
898 | ||
ad21e542 ZJS |
899 | <varlistentry> |
900 | <term><varname>CoredumpFilter=</varname></term> | |
901 | ||
902 | <listitem><para>Controls which types of memory mappings will be saved if the process dumps core | |
903 | (using the <filename>/proc/<replaceable>pid</replaceable>/coredump_filter</filename> file). Takes a | |
904 | whitespace-separated combination of mapping type names or numbers (with the default base 16). Mapping | |
905 | type names are <constant>private-anonymous</constant>, <constant>shared-anonymous</constant>, | |
906 | <constant>private-file-backed</constant>, <constant>shared-file-backed</constant>, | |
907 | <constant>elf-headers</constant>, <constant>private-huge</constant>, | |
908 | <constant>shared-huge</constant>, <constant>private-dax</constant>, <constant>shared-dax</constant>, | |
909 | and the special values <constant>all</constant> (all types) and <constant>default</constant> (the | |
910 | kernel default of <literal><constant>private-anonymous</constant> | |
911 | <constant>shared-anonymous</constant> <constant>elf-headers</constant> | |
912 | <constant>private-huge</constant></literal>). See | |
b7a47345 ZJS |
913 | <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
914 | for the meaning of the mapping types. When specified multiple times, all specified masks are | |
915 | ORed. When not set, or if the empty value is assigned, the inherited value is not changed.</para> | |
ad21e542 ZJS |
916 | |
917 | <example> | |
918 | <title>Add DAX pages to the dump filter</title> | |
919 | ||
920 | <programlisting>CoredumpFilter=default private-dax shared-dax</programlisting> | |
921 | </example> | |
922 | </listitem> | |
923 | </varlistentry> | |
924 | ||
b8afec21 LP |
925 | <varlistentry> |
926 | <term><varname>KeyringMode=</varname></term> | |
927 | ||
928 | <listitem><para>Controls how the kernel session keyring is set up for the service (see <citerefentry | |
929 | project='man-pages'><refentrytitle>session-keyring</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
930 | details on the session keyring). Takes one of <option>inherit</option>, <option>private</option>, | |
931 | <option>shared</option>. If set to <option>inherit</option> no special keyring setup is done, and the kernel's | |
932 | default behaviour is applied. If <option>private</option> is used a new session keyring is allocated when a | |
933 | service process is invoked, and it is not linked up with any user keyring. This is the recommended setting for | |
934 | system services, as this ensures that multiple services running under the same system user ID (in particular | |
935 | the root user) do not share their key material among each other. If <option>shared</option> is used a new | |
936 | session keyring is allocated as for <option>private</option>, but the user keyring of the user configured with | |
937 | <varname>User=</varname> is linked into it, so that keys assigned to the user may be requested by the unit's | |
938 | processes. In this modes multiple units running processes under the same user ID may share key material. Unless | |
939 | <option>inherit</option> is selected the unique invocation ID for the unit (see below) is added as a protected | |
940 | key by the name <literal>invocation_id</literal> to the newly created session keyring. Defaults to | |
00f5ad93 LP |
941 | <option>private</option> for services of the system service manager and to <option>inherit</option> for |
942 | non-service units and for services of the user service manager.</para></listitem> | |
b8afec21 LP |
943 | </varlistentry> |
944 | ||
945 | <varlistentry> | |
946 | <term><varname>OOMScoreAdjust=</varname></term> | |
947 | ||
8e74bf7f LP |
948 | <listitem><para>Sets the adjustment value for the Linux kernel's Out-Of-Memory (OOM) killer score for |
949 | executed processes. Takes an integer between -1000 (to disable OOM killing of processes of this unit) | |
950 | and 1000 (to make killing of processes of this unit under memory pressure very likely). See <ulink | |
951 | url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink> for details. If | |
952 | not specified defaults to the OOM score adjustment level of the service manager itself, which is | |
953 | normally at 0.</para> | |
954 | ||
955 | <para>Use the <varname>OOMPolicy=</varname> setting of service units to configure how the service | |
956 | manager shall react to the kernel OOM killer terminating a process of the service. See | |
957 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
958 | for details.</para></listitem> | |
b8afec21 LP |
959 | </varlistentry> |
960 | ||
961 | <varlistentry> | |
962 | <term><varname>TimerSlackNSec=</varname></term> | |
963 | <listitem><para>Sets the timer slack in nanoseconds for the executed processes. The timer slack controls the | |
964 | accuracy of wake-ups triggered by timers. See | |
965 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> for more | |
966 | information. Note that in contrast to most other time span definitions this parameter takes an integer value in | |
967 | nano-seconds if no unit is specified. The usual time units are understood too.</para></listitem> | |
968 | </varlistentry> | |
969 | ||
970 | <varlistentry> | |
971 | <term><varname>Personality=</varname></term> | |
972 | ||
973 | <listitem><para>Controls which kernel architecture <citerefentry | |
974 | project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry> shall report, | |
975 | when invoked by unit processes. Takes one of the architecture identifiers <constant>x86</constant>, | |
976 | <constant>x86-64</constant>, <constant>ppc</constant>, <constant>ppc-le</constant>, <constant>ppc64</constant>, | |
977 | <constant>ppc64-le</constant>, <constant>s390</constant> or <constant>s390x</constant>. Which personality | |
978 | architectures are supported depends on the system architecture. Usually the 64bit versions of the various | |
979 | system architectures support their immediate 32bit personality architecture counterpart, but no others. For | |
980 | example, <constant>x86-64</constant> systems support the <constant>x86-64</constant> and | |
981 | <constant>x86</constant> personalities but no others. The personality feature is useful when running 32-bit | |
982 | services on a 64-bit host system. If not specified, the personality is left unmodified and thus reflects the | |
983 | personality of the host system's kernel.</para></listitem> | |
984 | </varlistentry> | |
985 | ||
986 | <varlistentry> | |
987 | <term><varname>IgnoreSIGPIPE=</varname></term> | |
988 | ||
989 | <listitem><para>Takes a boolean argument. If true, causes <constant>SIGPIPE</constant> to be ignored in the | |
990 | executed process. Defaults to true because <constant>SIGPIPE</constant> generally is useful only in shell | |
991 | pipelines.</para></listitem> | |
992 | </varlistentry> | |
993 | ||
994 | </variablelist> | |
995 | </refsect1> | |
996 | ||
997 | <refsect1> | |
998 | <title>Scheduling</title> | |
999 | ||
e0e2ecd5 | 1000 | <variablelist class='unit-directives'> |
b8afec21 LP |
1001 | |
1002 | <varlistentry> | |
1003 | <term><varname>Nice=</varname></term> | |
1004 | ||
1005 | <listitem><para>Sets the default nice level (scheduling priority) for executed processes. Takes an integer | |
1006 | between -20 (highest priority) and 19 (lowest priority). See | |
1007 | <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry> for | |
1008 | details.</para></listitem> | |
1009 | </varlistentry> | |
1010 | ||
1011 | <varlistentry> | |
1012 | <term><varname>CPUSchedulingPolicy=</varname></term> | |
1013 | ||
1014 | <listitem><para>Sets the CPU scheduling policy for executed processes. Takes one of <option>other</option>, | |
1015 | <option>batch</option>, <option>idle</option>, <option>fifo</option> or <option>rr</option>. See | |
21556381 | 1016 | <citerefentry project='man-pages'><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
b8afec21 LP |
1017 | details.</para></listitem> |
1018 | </varlistentry> | |
1019 | ||
1020 | <varlistentry> | |
1021 | <term><varname>CPUSchedulingPriority=</varname></term> | |
1022 | ||
1023 | <listitem><para>Sets the CPU scheduling priority for executed processes. The available priority range depends | |
1024 | on the selected CPU scheduling policy (see above). For real-time scheduling policies an integer between 1 | |
1025 | (lowest priority) and 99 (highest priority) can be used. See | |
21556381 | 1026 | <citerefentry project='man-pages'><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
b8afec21 LP |
1027 | details. </para></listitem> |
1028 | </varlistentry> | |
1029 | ||
1030 | <varlistentry> | |
1031 | <term><varname>CPUSchedulingResetOnFork=</varname></term> | |
1032 | ||
0b4d17c9 ZJS |
1033 | <listitem><para>Takes a boolean argument. If true, elevated CPU scheduling priorities and policies |
1034 | will be reset when the executed processes call | |
1035 | <citerefentry project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry>, | |
1036 | and can hence not leak into child processes. See | |
21556381 | 1037 | <citerefentry project='man-pages'><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> |
0b4d17c9 | 1038 | for details. Defaults to false.</para></listitem> |
b8afec21 LP |
1039 | </varlistentry> |
1040 | ||
1041 | <varlistentry> | |
1042 | <term><varname>CPUAffinity=</varname></term> | |
1043 | ||
1044 | <listitem><para>Controls the CPU affinity of the executed processes. Takes a list of CPU indices or ranges | |
e2b2fb7f MS |
1045 | separated by either whitespace or commas. Alternatively, takes a special "numa" value in which case systemd |
1046 | automatically derives allowed CPU range based on the value of <varname>NUMAMask=</varname> option. CPU ranges | |
1047 | are specified by the lower and upper CPU indices separated by a dash. This option may be specified more than | |
1048 | once, in which case the specified CPU affinity masks are merged. If the empty string is assigned, the mask | |
1049 | is reset, all assignments prior to this will have no effect. See | |
21556381 | 1050 | <citerefentry project='man-pages'><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
b8afec21 LP |
1051 | details.</para></listitem> |
1052 | </varlistentry> | |
1053 | ||
b070c7c0 MS |
1054 | <varlistentry> |
1055 | <term><varname>NUMAPolicy=</varname></term> | |
1056 | ||
1057 | <listitem><para>Controls the NUMA memory policy of the executed processes. Takes a policy type, one of: | |
1058 | <option>default</option>, <option>preferred</option>, <option>bind</option>, <option>interleave</option> and | |
1059 | <option>local</option>. A list of NUMA nodes that should be associated with the policy must be specified | |
1060 | in <varname>NUMAMask=</varname>. For more details on each policy please see, | |
1061 | <citerefentry><refentrytitle>set_mempolicy</refentrytitle><manvolnum>2</manvolnum></citerefentry>. For overall | |
1062 | overview of NUMA support in Linux see, | |
e9dd6984 | 1063 | <citerefentry project='man-pages'><refentrytitle>numa</refentrytitle><manvolnum>7</manvolnum></citerefentry>. |
b070c7c0 MS |
1064 | </para></listitem> |
1065 | </varlistentry> | |
1066 | ||
1067 | <varlistentry> | |
1068 | <term><varname>NUMAMask=</varname></term> | |
1069 | ||
1070 | <listitem><para>Controls the NUMA node list which will be applied alongside with selected NUMA policy. | |
1071 | Takes a list of NUMA nodes and has the same syntax as a list of CPUs for <varname>CPUAffinity=</varname> | |
332d387f MS |
1072 | option or special "all" value which will include all available NUMA nodes in the mask. Note that the list |
1073 | of NUMA nodes is not required for <option>default</option> and <option>local</option> | |
b070c7c0 MS |
1074 | policies and for <option>preferred</option> policy we expect a single NUMA node.</para></listitem> |
1075 | </varlistentry> | |
1076 | ||
b8afec21 LP |
1077 | <varlistentry> |
1078 | <term><varname>IOSchedulingClass=</varname></term> | |
1079 | ||
1080 | <listitem><para>Sets the I/O scheduling class for executed processes. Takes an integer between 0 and 3 or one | |
1081 | of the strings <option>none</option>, <option>realtime</option>, <option>best-effort</option> or | |
617d253a YW |
1082 | <option>idle</option>. If the empty string is assigned to this option, all prior assignments to both |
1083 | <varname>IOSchedulingClass=</varname> and <varname>IOSchedulingPriority=</varname> have no effect. See | |
b8afec21 LP |
1084 | <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> for |
1085 | details.</para></listitem> | |
1086 | </varlistentry> | |
1087 | ||
1088 | <varlistentry> | |
1089 | <term><varname>IOSchedulingPriority=</varname></term> | |
1090 | ||
1091 | <listitem><para>Sets the I/O scheduling priority for executed processes. Takes an integer between 0 (highest | |
1092 | priority) and 7 (lowest priority). The available priorities depend on the selected I/O scheduling class (see | |
617d253a YW |
1093 | above). If the empty string is assigned to this option, all prior assignments to both |
1094 | <varname>IOSchedulingClass=</varname> and <varname>IOSchedulingPriority=</varname> have no effect. | |
1095 | See <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> for | |
b8afec21 LP |
1096 | details.</para></listitem> |
1097 | </varlistentry> | |
1098 | ||
1099 | </variablelist> | |
1100 | </refsect1> | |
1101 | ||
b8afec21 LP |
1102 | <refsect1> |
1103 | <title>Sandboxing</title> | |
1104 | ||
2d2224e4 LP |
1105 | <para>The following sandboxing options are an effective way to limit the exposure of the system towards the unit's |
1106 | processes. It is recommended to turn on as many of these options for each unit as is possible without negatively | |
1107 | affecting the process' ability to operate. Note that many of these sandboxing features are gracefully turned off on | |
1108 | systems where the underlying security mechanism is not available. For example, <varname>ProtectSystem=</varname> | |
1109 | has no effect if the kernel is built without file system namespacing or if the service manager runs in a container | |
1110 | manager that makes file system namespacing unavailable to its payload. Similar, | |
1111 | <varname>RestrictRealtime=</varname> has no effect on systems that lack support for SECCOMP system call filtering, | |
1112 | or in containers where support for this is turned off.</para> | |
1113 | ||
d287820d LP |
1114 | <para>Also note that some sandboxing functionality is generally not available in user services (i.e. services run |
1115 | by the per-user service manager). Specifically, the various settings requiring file system namespacing support | |
1116 | (such as <varname>ProtectSystem=</varname>) are not available, as the underlying kernel functionality is only | |
5749f855 AZ |
1117 | accessible to privileged processes. However, most namespacing settings, that will not work on their own in user |
1118 | services, will work when used in conjunction with <varname>PrivateUsers=</varname><option>true</option>.</para> | |
d287820d | 1119 | |
e0e2ecd5 | 1120 | <variablelist class='unit-directives'> |
b8afec21 LP |
1121 | |
1122 | <varlistentry> | |
1123 | <term><varname>ProtectSystem=</varname></term> | |
1124 | ||
1125 | <listitem><para>Takes a boolean argument or the special values <literal>full</literal> or | |
3b121157 | 1126 | <literal>strict</literal>. If true, mounts the <filename>/usr/</filename> and the boot loader |
26b81908 | 1127 | directories (<filename>/boot</filename> and <filename>/efi</filename>) read-only for processes |
3b121157 | 1128 | invoked by this unit. If set to <literal>full</literal>, the <filename>/etc/</filename> directory is |
26b81908 | 1129 | mounted read-only, too. If set to <literal>strict</literal> the entire file system hierarchy is |
3b121157 ZJS |
1130 | mounted read-only, except for the API file system subtrees <filename>/dev/</filename>, |
1131 | <filename>/proc/</filename> and <filename>/sys/</filename> (protect these directories using | |
b8afec21 LP |
1132 | <varname>PrivateDevices=</varname>, <varname>ProtectKernelTunables=</varname>, |
1133 | <varname>ProtectControlGroups=</varname>). This setting ensures that any modification of the vendor-supplied | |
1134 | operating system (and optionally its configuration, and local mounts) is prohibited for the service. It is | |
1135 | recommended to enable this setting for all long-running services, unless they are involved with system updates | |
1136 | or need to modify the operating system in other ways. If this option is used, | |
1137 | <varname>ReadWritePaths=</varname> may be used to exclude specific directories from being made read-only. This | |
0e18724e LP |
1138 | setting is implied if <varname>DynamicUser=</varname> is set. This setting cannot ensure protection in all |
1139 | cases. In general it has the same limitations as <varname>ReadOnlyPaths=</varname>, see below. Defaults to | |
1140 | off.</para></listitem> | |
b8afec21 LP |
1141 | </varlistentry> |
1142 | ||
1143 | <varlistentry> | |
1144 | <term><varname>ProtectHome=</varname></term> | |
1145 | ||
e4da7d8c | 1146 | <listitem><para>Takes a boolean argument or the special values <literal>read-only</literal> or |
3b121157 | 1147 | <literal>tmpfs</literal>. If true, the directories <filename>/home/</filename>, |
db8d154d ZJS |
1148 | <filename>/root</filename>, and <filename>/run/user</filename> are made inaccessible and empty for |
1149 | processes invoked by this unit. If set to <literal>read-only</literal>, the three directories are | |
1150 | made read-only instead. If set to <literal>tmpfs</literal>, temporary file systems are mounted on the | |
1151 | three directories in read-only mode. The value <literal>tmpfs</literal> is useful to hide home | |
1152 | directories not relevant to the processes invoked by the unit, while still allowing necessary | |
1153 | directories to be made visible when listed in <varname>BindPaths=</varname> or | |
1154 | <varname>BindReadOnlyPaths=</varname>.</para> | |
e4da7d8c YW |
1155 | |
1156 | <para>Setting this to <literal>yes</literal> is mostly equivalent to set the three directories in | |
1b2ad5d9 | 1157 | <varname>InaccessiblePaths=</varname>. Similarly, <literal>read-only</literal> is mostly equivalent to |
e4da7d8c | 1158 | <varname>ReadOnlyPaths=</varname>, and <literal>tmpfs</literal> is mostly equivalent to |
db8d154d | 1159 | <varname>TemporaryFileSystem=</varname> with <literal>:ro</literal>.</para> |
e4da7d8c | 1160 | |
db8d154d ZJS |
1161 | <para>It is recommended to enable this setting for all long-running services (in particular |
1162 | network-facing ones), to ensure they cannot get access to private user data, unless the services | |
1163 | actually require access to the user's private data. This setting is implied if | |
1164 | <varname>DynamicUser=</varname> is set. This setting cannot ensure protection in all cases. In | |
1165 | general it has the same limitations as <varname>ReadOnlyPaths=</varname>, see below.</para> | |
c4d4b5a7 LP |
1166 | |
1167 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
b8afec21 LP |
1168 | </varlistentry> |
1169 | ||
1170 | <varlistentry> | |
1171 | <term><varname>RuntimeDirectory=</varname></term> | |
1172 | <term><varname>StateDirectory=</varname></term> | |
1173 | <term><varname>CacheDirectory=</varname></term> | |
1174 | <term><varname>LogsDirectory=</varname></term> | |
1175 | <term><varname>ConfigurationDirectory=</varname></term> | |
1176 | ||
885a4e6c ZJS |
1177 | <listitem><para>These options take a whitespace-separated list of directory names. The specified |
1178 | directory names must be relative, and may not include <literal>..</literal>. If set, when the unit is | |
1179 | started, one or more directories by the specified names will be created (including their parents) | |
1180 | below the locations defined in the following table. Also, the corresponding environment variable will | |
1181 | be defined with the full paths of the directories. If multiple directories are set, then in the | |
1182 | environment variable the paths are concatenated with colon (<literal>:</literal>).</para> | |
8d00da49 | 1183 | <table> |
d491e65e YW |
1184 | <title>Automatic directory creation and environment variables</title> |
1185 | <tgroup cols='4'> | |
8d00da49 BV |
1186 | <thead> |
1187 | <row> | |
8601482c LP |
1188 | <entry>Directory</entry> |
1189 | <entry>Below path for system units</entry> | |
1190 | <entry>Below path for user units</entry> | |
1191 | <entry>Environment variable set</entry> | |
8d00da49 BV |
1192 | </row> |
1193 | </thead> | |
1194 | <tbody> | |
1195 | <row> | |
1196 | <entry><varname>RuntimeDirectory=</varname></entry> | |
8601482c | 1197 | <entry><filename>/run/</filename></entry> |
8d00da49 | 1198 | <entry><varname>$XDG_RUNTIME_DIR</varname></entry> |
d491e65e | 1199 | <entry><varname>$RUNTIME_DIRECTORY</varname></entry> |
8d00da49 BV |
1200 | </row> |
1201 | <row> | |
1202 | <entry><varname>StateDirectory=</varname></entry> | |
8601482c | 1203 | <entry><filename>/var/lib/</filename></entry> |
8d00da49 | 1204 | <entry><varname>$XDG_CONFIG_HOME</varname></entry> |
d491e65e | 1205 | <entry><varname>$STATE_DIRECTORY</varname></entry> |
8d00da49 BV |
1206 | </row> |
1207 | <row> | |
1208 | <entry><varname>CacheDirectory=</varname></entry> | |
8601482c | 1209 | <entry><filename>/var/cache/</filename></entry> |
8d00da49 | 1210 | <entry><varname>$XDG_CACHE_HOME</varname></entry> |
d491e65e | 1211 | <entry><varname>$CACHE_DIRECTORY</varname></entry> |
8d00da49 BV |
1212 | </row> |
1213 | <row> | |
1214 | <entry><varname>LogsDirectory=</varname></entry> | |
8601482c LP |
1215 | <entry><filename>/var/log/</filename></entry> |
1216 | <entry><varname>$XDG_CONFIG_HOME</varname><filename>/log/</filename></entry> | |
d491e65e | 1217 | <entry><varname>$LOGS_DIRECTORY</varname></entry> |
8d00da49 BV |
1218 | </row> |
1219 | <row> | |
1220 | <entry><varname>ConfigurationDirectory=</varname></entry> | |
8601482c | 1221 | <entry><filename>/etc/</filename></entry> |
8d00da49 | 1222 | <entry><varname>$XDG_CONFIG_HOME</varname></entry> |
d491e65e | 1223 | <entry><varname>$CONFIGURATION_DIRECTORY</varname></entry> |
8d00da49 BV |
1224 | </row> |
1225 | </tbody> | |
1226 | </tgroup> | |
1227 | </table> | |
f86fae61 | 1228 | |
6d463b8a LP |
1229 | <para>In case of <varname>RuntimeDirectory=</varname> the innermost subdirectories are removed when |
1230 | the unit is stopped. It is possible to preserve the specified directories in this case if | |
1231 | <varname>RuntimeDirectoryPreserve=</varname> is configured to <option>restart</option> or | |
1232 | <option>yes</option> (see below). The directories specified with <varname>StateDirectory=</varname>, | |
b8afec21 LP |
1233 | <varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname>, |
1234 | <varname>ConfigurationDirectory=</varname> are not removed when the unit is stopped.</para> | |
1235 | ||
1236 | <para>Except in case of <varname>ConfigurationDirectory=</varname>, the innermost specified directories will be | |
1237 | owned by the user and group specified in <varname>User=</varname> and <varname>Group=</varname>. If the | |
1238 | specified directories already exist and their owning user or group do not match the configured ones, all files | |
1239 | and directories below the specified directories as well as the directories themselves will have their file | |
1240 | ownership recursively changed to match what is configured. As an optimization, if the specified directories are | |
1241 | already owned by the right user and group, files and directories below of them are left as-is, even if they do | |
1242 | not match what is requested. The innermost specified directories will have their access mode adjusted to the | |
1243 | what is specified in <varname>RuntimeDirectoryMode=</varname>, <varname>StateDirectoryMode=</varname>, | |
1244 | <varname>CacheDirectoryMode=</varname>, <varname>LogsDirectoryMode=</varname> and | |
1245 | <varname>ConfigurationDirectoryMode=</varname>.</para> | |
5aaeeffb | 1246 | |
b8afec21 LP |
1247 | <para>These options imply <varname>BindPaths=</varname> for the specified paths. When combined with |
1248 | <varname>RootDirectory=</varname> or <varname>RootImage=</varname> these paths always reside on the host and | |
1249 | are mounted from there into the unit's file system namespace.</para> | |
798d3a52 | 1250 | |
e9dd6984 ZJS |
1251 | <para>If <varname>DynamicUser=</varname> is used in conjunction with |
1252 | <varname>StateDirectory=</varname>, the logic for <varname>CacheDirectory=</varname> and | |
1253 | <varname>LogsDirectory=</varname> is slightly altered: the directories are created below | |
1254 | <filename>/var/lib/private</filename>, <filename>/var/cache/private</filename> and | |
b8afec21 | 1255 | <filename>/var/log/private</filename>, respectively, which are host directories made inaccessible to |
e9dd6984 ZJS |
1256 | unprivileged users, which ensures that access to these directories cannot be gained through dynamic |
1257 | user ID recycling. Symbolic links are created to hide this difference in behaviour. Both from | |
1258 | perspective of the host and from inside the unit, the relevant directories hence always appear | |
1259 | directly below <filename>/var/lib</filename>, <filename>/var/cache</filename> and | |
1260 | <filename>/var/log</filename>.</para> | |
798d3a52 | 1261 | |
b8afec21 LP |
1262 | <para>Use <varname>RuntimeDirectory=</varname> to manage one or more runtime directories for the unit and bind |
1263 | their lifetime to the daemon runtime. This is particularly useful for unprivileged daemons that cannot create | |
3b121157 | 1264 | runtime directories in <filename>/run/</filename> due to lack of privileges, and to make sure the runtime |
b8afec21 LP |
1265 | directory is cleaned up automatically after use. For runtime directories that require more complex or different |
1266 | configuration or lifetime guarantees, please consider using | |
1267 | <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
de7070b4 | 1268 | |
a9a50bd6 | 1269 | <para>The directories defined by these options are always created under the standard paths used by systemd |
3b121157 | 1270 | (<filename>/var/</filename>, <filename>/run/</filename>, <filename>/etc/</filename>, …). If the service needs |
a9a50bd6 PW |
1271 | directories in a different location, a different mechanism has to be used to create them.</para> |
1272 | ||
1273 | <para><citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> provides | |
1274 | functionality that overlaps with these options. Using these options is recommended, because the lifetime of | |
1275 | the directories is tied directly to the lifetime of the unit, and it is not necessary to ensure that the | |
1276 | <filename>tmpfiles.d</filename> configuration is executed before the unit is started.</para> | |
1277 | ||
8c8208cb LP |
1278 | <para>To remove any of the directories created by these settings, use the <command>systemctl clean |
1279 | …</command> command on the relevant units, see | |
1280 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> for | |
1281 | details.</para> | |
1282 | ||
b8afec21 LP |
1283 | <para>Example: if a system service unit has the following, |
1284 | <programlisting>RuntimeDirectory=foo/bar baz</programlisting> | |
211c99c7 | 1285 | the service manager creates <filename index='false'>/run/foo</filename> (if it does not exist), |
f8b68539 ZJS |
1286 | |
1287 | <filename index='false'>/run/foo/bar</filename>, and <filename index='false'>/run/baz</filename>. The | |
1288 | directories <filename index='false'>/run/foo/bar</filename> and | |
1289 | <filename index='false'>/run/baz</filename> except <filename index='false'>/run/foo</filename> are | |
b8afec21 | 1290 | owned by the user and group specified in <varname>User=</varname> and <varname>Group=</varname>, and removed |
d491e65e YW |
1291 | when the service is stopped.</para> |
1292 | ||
1293 | <para>Example: if a system service unit has the following, | |
1294 | <programlisting>RuntimeDirectory=foo/bar | |
1295 | StateDirectory=aaa/bbb ccc</programlisting> | |
1296 | then the environment variable <literal>RUNTIME_DIRECTORY</literal> is set with <literal>/run/foo/bar</literal>, and | |
1297 | <literal>STATE_DIRECTORY</literal> is set with <literal>/var/lib/aaa/bbb:/var/lib/ccc</literal>.</para></listitem> | |
798d3a52 ZJS |
1298 | </varlistentry> |
1299 | ||
ece87975 | 1300 | <varlistentry> |
b8afec21 LP |
1301 | <term><varname>RuntimeDirectoryMode=</varname></term> |
1302 | <term><varname>StateDirectoryMode=</varname></term> | |
1303 | <term><varname>CacheDirectoryMode=</varname></term> | |
1304 | <term><varname>LogsDirectoryMode=</varname></term> | |
1305 | <term><varname>ConfigurationDirectoryMode=</varname></term> | |
ece87975 | 1306 | |
b8afec21 LP |
1307 | <listitem><para>Specifies the access mode of the directories specified in <varname>RuntimeDirectory=</varname>, |
1308 | <varname>StateDirectory=</varname>, <varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname>, or | |
1309 | <varname>ConfigurationDirectory=</varname>, respectively, as an octal number. Defaults to | |
1310 | <constant>0755</constant>. See "Permissions" in <citerefentry | |
1311 | project='man-pages'><refentrytitle>path_resolution</refentrytitle><manvolnum>7</manvolnum></citerefentry> for a | |
1312 | discussion of the meaning of permission bits.</para></listitem> | |
ece87975 IP |
1313 | </varlistentry> |
1314 | ||
798d3a52 | 1315 | <varlistentry> |
b8afec21 LP |
1316 | <term><varname>RuntimeDirectoryPreserve=</varname></term> |
1317 | ||
1318 | <listitem><para>Takes a boolean argument or <option>restart</option>. If set to <option>no</option> (the | |
1319 | default), the directories specified in <varname>RuntimeDirectory=</varname> are always removed when the service | |
1320 | stops. If set to <option>restart</option> the directories are preserved when the service is both automatically | |
1321 | and manually restarted. Here, the automatic restart means the operation specified in | |
1322 | <varname>Restart=</varname>, and manual restart means the one triggered by <command>systemctl restart | |
1323 | foo.service</command>. If set to <option>yes</option>, then the directories are not removed when the service is | |
3b121157 | 1324 | stopped. Note that since the runtime directory <filename>/run/</filename> is a mount point of |
b8afec21 LP |
1325 | <literal>tmpfs</literal>, then for system services the directories specified in |
1326 | <varname>RuntimeDirectory=</varname> are removed when the system is rebooted.</para></listitem> | |
798d3a52 ZJS |
1327 | </varlistentry> |
1328 | ||
bd9014c3 YW |
1329 | <varlistentry> |
1330 | <term><varname>TimeoutCleanSec=</varname></term> | |
1331 | <listitem><para>Configures a timeout on the clean-up operation requested through <command>systemctl | |
1332 | clean …</command>, see | |
1333 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> for | |
1334 | details. Takes the usual time values and defaults to <constant>infinity</constant>, i.e. by default | |
201632e3 ZJS |
1335 | no timeout is applied. If a timeout is configured the clean operation will be aborted forcibly when |
1336 | the timeout is reached, potentially leaving resources on disk.</para></listitem> | |
bd9014c3 YW |
1337 | </varlistentry> |
1338 | ||
798d3a52 | 1339 | <varlistentry> |
2a624c36 AP |
1340 | <term><varname>ReadWritePaths=</varname></term> |
1341 | <term><varname>ReadOnlyPaths=</varname></term> | |
1342 | <term><varname>InaccessiblePaths=</varname></term> | |
798d3a52 | 1343 | |
885a4e6c ZJS |
1344 | <listitem><para>Sets up a new file system namespace for executed processes. These options may be used |
1345 | to limit access a process has to the file system. Each setting takes a space-separated list of paths | |
1346 | relative to the host's root directory (i.e. the system running the service manager). Note that if | |
1347 | paths contain symlinks, they are resolved relative to the root directory set with | |
915e6d16 | 1348 | <varname>RootDirectory=</varname>/<varname>RootImage=</varname>.</para> |
effbd6d2 | 1349 | |
6b000af4 LP |
1350 | <para>Paths listed in <varname>ReadWritePaths=</varname> are accessible from within the namespace |
1351 | with the same access modes as from outside of it. Paths listed in <varname>ReadOnlyPaths=</varname> | |
1352 | are accessible for reading only, writing will be refused even if the usual file access controls would | |
1353 | permit this. Nest <varname>ReadWritePaths=</varname> inside of <varname>ReadOnlyPaths=</varname> in | |
1354 | order to provide writable subdirectories within read-only directories. Use | |
1355 | <varname>ReadWritePaths=</varname> in order to allow-list specific paths for write access if | |
1356 | <varname>ProtectSystem=strict</varname> is used.</para> | |
e568a92d YW |
1357 | |
1358 | <para>Paths listed in <varname>InaccessiblePaths=</varname> will be made inaccessible for processes inside | |
1359 | the namespace along with everything below them in the file system hierarchy. This may be more restrictive than | |
1360 | desired, because it is not possible to nest <varname>ReadWritePaths=</varname>, <varname>ReadOnlyPaths=</varname>, | |
1361 | <varname>BindPaths=</varname>, or <varname>BindReadOnlyPaths=</varname> inside it. For a more flexible option, | |
1362 | see <varname>TemporaryFileSystem=</varname>.</para> | |
effbd6d2 | 1363 | |
0e18724e | 1364 | <para>Non-directory paths may be specified as well. These options may be specified more than once, |
effbd6d2 LP |
1365 | in which case all paths listed will have limited access from within the namespace. If the empty string is |
1366 | assigned to this option, the specific list is reset, and all prior assignments have no effect.</para> | |
1367 | ||
e778185b | 1368 | <para>Paths in <varname>ReadWritePaths=</varname>, <varname>ReadOnlyPaths=</varname> and |
5327c910 LP |
1369 | <varname>InaccessiblePaths=</varname> may be prefixed with <literal>-</literal>, in which case they will be |
1370 | ignored when they do not exist. If prefixed with <literal>+</literal> the paths are taken relative to the root | |
915e6d16 LP |
1371 | directory of the unit, as configured with <varname>RootDirectory=</varname>/<varname>RootImage=</varname>, |
1372 | instead of relative to the root directory of the host (see above). When combining <literal>-</literal> and | |
1373 | <literal>+</literal> on the same path make sure to specify <literal>-</literal> first, and <literal>+</literal> | |
1374 | second.</para> | |
5327c910 | 1375 | |
0e18724e LP |
1376 | <para>Note that these settings will disconnect propagation of mounts from the unit's processes to the |
1377 | host. This means that this setting may not be used for services which shall be able to install mount points in | |
1378 | the main mount namespace. For <varname>ReadWritePaths=</varname> and <varname>ReadOnlyPaths=</varname> | |
1379 | propagation in the other direction is not affected, i.e. mounts created on the host generally appear in the | |
1380 | unit processes' namespace, and mounts removed on the host also disappear there too. In particular, note that | |
1381 | mount propagation from host to unit will result in unmodified mounts to be created in the unit's namespace, | |
1382 | i.e. writable mounts appearing on the host will be writable in the unit's namespace too, even when propagated | |
1383 | below a path marked with <varname>ReadOnlyPaths=</varname>! Restricting access with these options hence does | |
1384 | not extend to submounts of a directory that are created later on. This means the lock-down offered by that | |
1385 | setting is not complete, and does not offer full protection. </para> | |
1386 | ||
1387 | <para>Note that the effect of these settings may be undone by privileged processes. In order to set up an | |
1388 | effective sandboxed environment for a unit it is thus recommended to combine these settings with either | |
5327c910 | 1389 | <varname>CapabilityBoundingSet=~CAP_SYS_ADMIN</varname> or |
c4d4b5a7 LP |
1390 | <varname>SystemCallFilter=~@mount</varname>.</para> |
1391 | ||
1392 | <xi:include href="system-only.xml" xpointer="plural"/></listitem> | |
798d3a52 ZJS |
1393 | </varlistentry> |
1394 | ||
c10b460b YW |
1395 | <varlistentry> |
1396 | <term><varname>TemporaryFileSystem=</varname></term> | |
1397 | ||
1398 | <listitem><para>Takes a space-separated list of mount points for temporary file systems (tmpfs). If set, a new file | |
1399 | system namespace is set up for executed processes, and a temporary file system is mounted on each mount point. | |
1400 | This option may be specified more than once, in which case temporary file systems are mounted on all listed mount | |
1401 | points. If the empty string is assigned to this option, the list is reset, and all prior assignments have no effect. | |
1402 | Each mount point may optionally be suffixed with a colon (<literal>:</literal>) and mount options such as | |
1403 | <literal>size=10%</literal> or <literal>ro</literal>. By default, each temporary file system is mounted | |
1404 | with <literal>nodev,strictatime,mode=0755</literal>. These can be disabled by explicitly specifying the corresponding | |
1405 | mount options, e.g., <literal>dev</literal> or <literal>nostrictatime</literal>.</para> | |
1406 | ||
1407 | <para>This is useful to hide files or directories not relevant to the processes invoked by the unit, while necessary | |
1408 | files or directories can be still accessed by combining with <varname>BindPaths=</varname> or | |
db8d154d | 1409 | <varname>BindReadOnlyPaths=</varname>:</para> |
c10b460b YW |
1410 | |
1411 | <para>Example: if a unit has the following, | |
1412 | <programlisting>TemporaryFileSystem=/var:ro | |
1413 | BindReadOnlyPaths=/var/lib/systemd</programlisting> | |
3b121157 | 1414 | then the invoked processes by the unit cannot see any files or directories under <filename>/var/</filename> except for |
c4d4b5a7 LP |
1415 | <filename>/var/lib/systemd</filename> or its contents.</para> |
1416 | ||
1417 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
c10b460b YW |
1418 | </varlistentry> |
1419 | ||
798d3a52 ZJS |
1420 | <varlistentry> |
1421 | <term><varname>PrivateTmp=</varname></term> | |
1422 | ||
3b121157 ZJS |
1423 | <listitem><para>Takes a boolean argument. If true, sets up a new file system namespace for the |
1424 | executed processes and mounts private <filename>/tmp/</filename> and <filename>/var/tmp/</filename> | |
1425 | directories inside it that are not shared by processes outside of the namespace. This is useful to | |
1426 | secure access to temporary files of the process, but makes sharing between processes via | |
1427 | <filename>/tmp/</filename> or <filename>/var/tmp/</filename> impossible. If this is enabled, all | |
1428 | temporary files created by a service in these directories will be removed after the service is | |
1429 | stopped. Defaults to false. It is possible to run two or more units within the same private | |
1430 | <filename>/tmp/</filename> and <filename>/var/tmp/</filename> namespace by using the | |
798d3a52 | 1431 | <varname>JoinsNamespaceOf=</varname> directive, see |
00d9ef85 | 1432 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for |
effbd6d2 | 1433 | details. This setting is implied if <varname>DynamicUser=</varname> is set. For this setting the same |
3b121157 ZJS |
1434 | restrictions regarding mount propagation and privileges apply as for |
1435 | <varname>ReadOnlyPaths=</varname> and related calls, see above. Enabling this setting has the side | |
1436 | effect of adding <varname>Requires=</varname> and <varname>After=</varname> dependencies on all mount | |
1437 | units necessary to access <filename>/tmp/</filename> and <filename>/var/tmp/</filename>. Moreover an | |
1438 | implicitly <varname>After=</varname> ordering on | |
d71f0505 | 1439 | <citerefentry><refentrytitle>systemd-tmpfiles-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
b0238568 ZJS |
1440 | is added.</para> |
1441 | ||
b8afec21 LP |
1442 | <para>Note that the implementation of this setting might be impossible (for example if mount namespaces are not |
1443 | available), and the unit should be written in a way that does not solely rely on this setting for | |
c4d4b5a7 LP |
1444 | security.</para> |
1445 | ||
1446 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1447 | </varlistentry> |
1448 | ||
1449 | <varlistentry> | |
1450 | <term><varname>PrivateDevices=</varname></term> | |
1451 | ||
3b121157 | 1452 | <listitem><para>Takes a boolean argument. If true, sets up a new <filename>/dev/</filename> mount for the |
b0238568 | 1453 | executed processes and only adds API pseudo devices such as <filename>/dev/null</filename>, |
b8afec21 LP |
1454 | <filename>/dev/zero</filename> or <filename>/dev/random</filename> (as well as the pseudo TTY subsystem) to it, |
1455 | but no physical devices such as <filename>/dev/sda</filename>, system memory <filename>/dev/mem</filename>, | |
1456 | system ports <filename>/dev/port</filename> and others. This is useful to securely turn off physical device | |
1457 | access by the executed process. Defaults to false. Enabling this option will install a system call filter to | |
1458 | block low-level I/O system calls that are grouped in the <varname>@raw-io</varname> set, will also remove | |
1459 | <constant>CAP_MKNOD</constant> and <constant>CAP_SYS_RAWIO</constant> from the capability bounding set for the | |
1460 | unit (see above), and set <varname>DevicePolicy=closed</varname> (see | |
798d3a52 | 1461 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
effbd6d2 LP |
1462 | for details). Note that using this setting will disconnect propagation of mounts from the service to the host |
1463 | (propagation in the opposite direction continues to work). This means that this setting may not be used for | |
b8afec21 | 1464 | services which shall be able to install mount points in the main mount namespace. The new |
3b121157 | 1465 | <filename>/dev/</filename> will be mounted read-only and 'noexec'. The latter may break old programs which try |
b8afec21 LP |
1466 | to set up executable memory by using |
1467 | <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry> of | |
1468 | <filename>/dev/zero</filename> instead of using <constant>MAP_ANON</constant>. For this setting the same | |
1469 | restrictions regarding mount propagation and privileges apply as for <varname>ReadOnlyPaths=</varname> and | |
1470 | related calls, see above. If turned on and if running in user mode, or in system mode, but without the | |
1471 | <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=</varname>), | |
1472 | <varname>NoNewPrivileges=yes</varname> is implied.</para> | |
b0238568 | 1473 | |
b8afec21 LP |
1474 | <para>Note that the implementation of this setting might be impossible (for example if mount namespaces are not |
1475 | available), and the unit should be written in a way that does not solely rely on this setting for | |
c4d4b5a7 LP |
1476 | security.</para> |
1477 | ||
1478 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1479 | </varlistentry> |
1480 | ||
1481 | <varlistentry> | |
1482 | <term><varname>PrivateNetwork=</varname></term> | |
1483 | ||
b8afec21 LP |
1484 | <listitem><para>Takes a boolean argument. If true, sets up a new network namespace for the executed processes |
1485 | and configures only the loopback network device <literal>lo</literal> inside it. No other network devices will | |
1486 | be available to the executed process. This is useful to turn off network access by the executed process. | |
1487 | Defaults to false. It is possible to run two or more units within the same private network namespace by using | |
1488 | the <varname>JoinsNamespaceOf=</varname> directive, see | |
1489 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for | |
9236cabf LP |
1490 | details. Note that this option will disconnect all socket families from the host, including |
1491 | <constant>AF_NETLINK</constant> and <constant>AF_UNIX</constant>. Effectively, for | |
1492 | <constant>AF_NETLINK</constant> this means that device configuration events received from | |
1493 | <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> are | |
1494 | not delivered to the unit's processes. And for <constant>AF_UNIX</constant> this has the effect that | |
1495 | <constant>AF_UNIX</constant> sockets in the abstract socket namespace of the host will become unavailable to | |
1496 | the unit's processes (however, those located in the file system will continue to be accessible).</para> | |
b8afec21 LP |
1497 | |
1498 | <para>Note that the implementation of this setting might be impossible (for example if network namespaces are | |
1499 | not available), and the unit should be written in a way that does not solely rely on this setting for | |
4107452e LP |
1500 | security.</para> |
1501 | ||
1502 | <para>When this option is used on a socket unit any sockets bound on behalf of this unit will be | |
1503 | bound within a private network namespace. This may be combined with | |
1504 | <varname>JoinsNamespaceOf=</varname> to listen on sockets inside of network namespaces of other | |
c4d4b5a7 LP |
1505 | services.</para> |
1506 | ||
1507 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
4107452e LP |
1508 | </varlistentry> |
1509 | ||
1510 | <varlistentry> | |
1511 | <term><varname>NetworkNamespacePath=</varname></term> | |
1512 | ||
1513 | <listitem><para>Takes an absolute file system path refererring to a Linux network namespace | |
1514 | pseudo-file (i.e. a file like <filename>/proc/$PID/ns/net</filename> or a bind mount or symlink to | |
1515 | one). When set the invoked processes are added to the network namespace referenced by that path. The | |
1516 | path has to point to a valid namespace file at the moment the processes are forked off. If this | |
1517 | option is used <varname>PrivateNetwork=</varname> has no effect. If this option is used together with | |
1518 | <varname>JoinsNamespaceOf=</varname> then it only has an effect if this unit is started before any of | |
1519 | the listed units that have <varname>PrivateNetwork=</varname> or | |
1520 | <varname>NetworkNamespacePath=</varname> configured, as otherwise the network namespace of those | |
1521 | units is reused.</para> | |
1522 | ||
1523 | <para>When this option is used on a socket unit any sockets bound on behalf of this unit will be | |
c4d4b5a7 LP |
1524 | bound within the specified network namespace.</para> |
1525 | ||
1526 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1527 | </varlistentry> |
1528 | ||
1529 | <varlistentry> | |
d251207d LP |
1530 | <term><varname>PrivateUsers=</varname></term> |
1531 | ||
1532 | <listitem><para>Takes a boolean argument. If true, sets up a new user namespace for the executed processes and | |
1533 | configures a minimal user and group mapping, that maps the <literal>root</literal> user and group as well as | |
1534 | the unit's own user and group to themselves and everything else to the <literal>nobody</literal> user and | |
1535 | group. This is useful to securely detach the user and group databases used by the unit from the rest of the | |
1536 | system, and thus to create an effective sandbox environment. All files, directories, processes, IPC objects and | |
2dd67817 | 1537 | other resources owned by users/groups not equaling <literal>root</literal> or the unit's own will stay visible |
d251207d LP |
1538 | from within the unit but appear owned by the <literal>nobody</literal> user and group. If this mode is enabled, |
1539 | all unit processes are run without privileges in the host user namespace (regardless if the unit's own | |
1540 | user/group is <literal>root</literal> or not). Specifically this means that the process will have zero process | |
1541 | capabilities on the host's user namespace, but full capabilities within the service's user namespace. Settings | |
1542 | such as <varname>CapabilityBoundingSet=</varname> will affect only the latter, and there's no way to acquire | |
1543 | additional capabilities in the host's user namespace. Defaults to off.</para> | |
1544 | ||
5749f855 AZ |
1545 | <para>When this setting is set up by a per-user instance of the service manager, the mapping of the |
1546 | <literal>root</literal> user and group to itself is omitted (unless the user manager is root). | |
1547 | Additionally, in the per-user instance manager case, the | |
1548 | user namespace will be set up before most other namespaces. This means that combining | |
1549 | <varname>PrivateUsers=</varname><option>true</option> with other namespaces will enable use of features not | |
1550 | normally supported by the per-user instances of the service manager.</para> | |
1551 | ||
915e6d16 LP |
1552 | <para>This setting is particularly useful in conjunction with |
1553 | <varname>RootDirectory=</varname>/<varname>RootImage=</varname>, as the need to synchronize the user and group | |
1554 | databases in the root directory and on the host is reduced, as the only users and groups who need to be matched | |
b0238568 ZJS |
1555 | are <literal>root</literal>, <literal>nobody</literal> and the unit's own user and group.</para> |
1556 | ||
b8afec21 LP |
1557 | <para>Note that the implementation of this setting might be impossible (for example if user namespaces are not |
1558 | available), and the unit should be written in a way that does not solely rely on this setting for | |
5749f855 | 1559 | security.</para></listitem> |
d251207d LP |
1560 | </varlistentry> |
1561 | ||
aecd5ac6 TM |
1562 | <varlistentry> |
1563 | <term><varname>ProtectHostname=</varname></term> | |
1564 | ||
1565 | <listitem><para>Takes a boolean argument. When set, sets up a new UTS namespace for the executed | |
1566 | processes. In addition, changing hostname or domainname is prevented. Defaults to off.</para> | |
1567 | ||
8df87b43 LP |
1568 | <para>Note that the implementation of this setting might be impossible (for example if UTS namespaces |
1569 | are not available), and the unit should be written in a way that does not solely rely on this setting | |
1570 | for security.</para> | |
1571 | ||
1572 | <para>Note that when this option is enabled for a service hostname changes no longer propagate from | |
1573 | the system into the service, it is hence not suitable for services that need to take notice of system | |
c4d4b5a7 LP |
1574 | hostname changes dynamically.</para> |
1575 | ||
1576 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
aecd5ac6 TM |
1577 | </varlistentry> |
1578 | ||
022d3345 KK |
1579 | <varlistentry> |
1580 | <term><varname>ProtectClock=</varname></term> | |
1581 | ||
1582 | <listitem><para>Takes a boolean argument. If set, writes to the hardware clock or system clock will be denied. | |
1583 | It is recommended to turn this on for most services that do not need modify the clock. Defaults to off. Enabling | |
1584 | this option removes <constant>CAP_SYS_TIME</constant> and <constant>CAP_WAKE_ALARM</constant> from the | |
1585 | capability bounding set for this unit, installs a system call filter to block calls that can set the | |
1586 | clock, and <varname>DeviceAllow=char-rtc r</varname> is implied. This ensures <filename>/dev/rtc0</filename>, | |
e9dd6984 | 1587 | <filename>/dev/rtc1</filename>, etc. are made read-only to the service. See |
022d3345 KK |
1588 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
1589 | for the details about <varname>DeviceAllow=</varname>.</para> | |
1590 | ||
1591 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
1592 | </varlistentry> | |
1593 | ||
59eeb84b LP |
1594 | <varlistentry> |
1595 | <term><varname>ProtectKernelTunables=</varname></term> | |
1596 | ||
1597 | <listitem><para>Takes a boolean argument. If true, kernel variables accessible through | |
3b121157 | 1598 | <filename>/proc/sys/</filename>, <filename>/sys/</filename>, <filename>/proc/sysrq-trigger</filename>, |
49accde7 DH |
1599 | <filename>/proc/latency_stats</filename>, <filename>/proc/acpi</filename>, |
1600 | <filename>/proc/timer_stats</filename>, <filename>/proc/fs</filename> and <filename>/proc/irq</filename> will | |
525872bf LP |
1601 | be made read-only to all processes of the unit. Usually, tunable kernel variables should be initialized only at |
1602 | boot-time, for example with the | |
1603 | <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> mechanism. Few | |
1604 | services need to write to these at runtime; it is hence recommended to turn this on for most services. For this | |
1605 | setting the same restrictions regarding mount propagation and privileges apply as for | |
1606 | <varname>ReadOnlyPaths=</varname> and related calls, see above. Defaults to off. If turned on and if running | |
1607 | in user mode, or in system mode, but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. services | |
1608 | for which <varname>User=</varname> is set), <varname>NoNewPrivileges=yes</varname> is implied. Note that this | |
1609 | option does not prevent indirect changes to kernel tunables effected by IPC calls to other processes. However, | |
1610 | <varname>InaccessiblePaths=</varname> may be used to make relevant IPC file system objects inaccessible. If | |
1611 | <varname>ProtectKernelTunables=</varname> is set, <varname>MountAPIVFS=yes</varname> is | |
c4d4b5a7 LP |
1612 | implied.</para> |
1613 | ||
1614 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
59eeb84b LP |
1615 | </varlistentry> |
1616 | ||
85265556 DH |
1617 | <varlistentry> |
1618 | <term><varname>ProtectKernelModules=</varname></term> | |
1619 | ||
1b2ad5d9 MB |
1620 | <listitem><para>Takes a boolean argument. If true, explicit module loading will be denied. This allows |
1621 | module load and unload operations to be turned off on modular kernels. It is recommended to turn this on for most services | |
bf2d3d7c | 1622 | that do not need special file systems or extra kernel modules to work. Defaults to off. Enabling this option |
b8afec21 LP |
1623 | removes <constant>CAP_SYS_MODULE</constant> from the capability bounding set for the unit, and installs a |
1624 | system call filter to block module system calls, also <filename>/usr/lib/modules</filename> is made | |
1625 | inaccessible. For this setting the same restrictions regarding mount propagation and privileges apply as for | |
1626 | <varname>ReadOnlyPaths=</varname> and related calls, see above. Note that limited automatic module loading due | |
1627 | to user configuration or kernel mapping tables might still happen as side effect of requested user operations, | |
85265556 DH |
1628 | both privileged and unprivileged. To disable module auto-load feature please see |
1629 | <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1630 | <constant>kernel.modules_disabled</constant> mechanism and | |
b8afec21 LP |
1631 | <filename>/proc/sys/kernel/modules_disabled</filename> documentation. If turned on and if running in user |
1632 | mode, or in system mode, but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting | |
c4d4b5a7 LP |
1633 | <varname>User=</varname>), <varname>NoNewPrivileges=yes</varname> is implied.</para> |
1634 | ||
1635 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
85265556 DH |
1636 | </varlistentry> |
1637 | ||
d916e35b KK |
1638 | <varlistentry> |
1639 | <term><varname>ProtectKernelLogs=</varname></term> | |
1640 | ||
1641 | <listitem><para>Takes a boolean argument. If true, access to the kernel log ring buffer will be denied. It is | |
1642 | recommended to turn this on for most services that do not need to read from or write to the kernel log ring | |
1643 | buffer. Enabling this option removes <constant>CAP_SYSLOG</constant> from the capability bounding set for this | |
1644 | unit, and installs a system call filter to block the | |
1645 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1646 | system call (not to be confused with the libc API | |
1647 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
1648 | for userspace logging). The kernel exposes its log buffer to userspace via <filename>/dev/kmsg</filename> and | |
1649 | <filename>/proc/kmsg</filename>. If enabled, these are made inaccessible to all the processes in the unit.</para> | |
1650 | ||
1651 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
1652 | </varlistentry> | |
1653 | ||
59eeb84b LP |
1654 | <varlistentry> |
1655 | <term><varname>ProtectControlGroups=</varname></term> | |
1656 | ||
effbd6d2 LP |
1657 | <listitem><para>Takes a boolean argument. If true, the Linux Control Groups (<citerefentry |
1658 | project='man-pages'><refentrytitle>cgroups</refentrytitle><manvolnum>7</manvolnum></citerefentry>) hierarchies | |
3b121157 | 1659 | accessible through <filename>/sys/fs/cgroup/</filename> will be made read-only to all processes of the |
effbd6d2 LP |
1660 | unit. Except for container managers no services should require write access to the control groups hierarchies; |
1661 | it is hence recommended to turn this on for most services. For this setting the same restrictions regarding | |
1662 | mount propagation and privileges apply as for <varname>ReadOnlyPaths=</varname> and related calls, see | |
b8afec21 | 1663 | above. Defaults to off. If <varname>ProtectControlGroups=</varname> is set, <varname>MountAPIVFS=yes</varname> |
c4d4b5a7 LP |
1664 | is implied.</para> |
1665 | ||
1666 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1667 | </varlistentry> |
1668 | ||
1669 | <varlistentry> | |
b8afec21 | 1670 | <term><varname>RestrictAddressFamilies=</varname></term> |
798d3a52 | 1671 | |
6b000af4 LP |
1672 | <listitem><para>Restricts the set of socket address families accessible to the processes of this |
1673 | unit. Takes a space-separated list of address family names to allow-list, such as | |
1674 | <constant>AF_UNIX</constant>, <constant>AF_INET</constant> or <constant>AF_INET6</constant>. When | |
1675 | prefixed with <constant>~</constant> the listed address families will be applied as deny list, | |
1676 | otherwise as allow list. Note that this restricts access to the <citerefentry | |
1677 | project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1678 | system call only. Sockets passed into the process by other means (for example, by using socket | |
1679 | activation with socket units, see | |
1680 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>) | |
1681 | are unaffected. Also, sockets created with <function>socketpair()</function> (which creates connected | |
1682 | AF_UNIX sockets only) are unaffected. Note that this option has no effect on 32-bit x86, s390, s390x, | |
e9dd6984 | 1683 | mips, mips-le, ppc, ppc-le, ppc64, ppc64-le and is ignored (but works correctly on other ABIs, |
6b000af4 LP |
1684 | including x86-64). Note that on systems supporting multiple ABIs (such as x86/x86-64) it is |
1685 | recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the | |
1686 | restrictions of this option. Specifically, it is recommended to combine this option with | |
1687 | <varname>SystemCallArchitectures=native</varname> or similar. If running in user mode, or in system | |
1688 | mode, but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting | |
1689 | <varname>User=nobody</varname>), <varname>NoNewPrivileges=yes</varname> is implied. By default, no | |
1690 | restrictions apply, all address families are accessible to processes. If assigned the empty string, | |
1691 | any previous address family restriction changes are undone. This setting does not affect commands | |
1692 | prefixed with <literal>+</literal>.</para> | |
b8afec21 LP |
1693 | |
1694 | <para>Use this option to limit exposure of processes to remote access, in particular via exotic and sensitive | |
1695 | network protocols, such as <constant>AF_PACKET</constant>. Note that in most cases, the local | |
6b000af4 | 1696 | <constant>AF_UNIX</constant> address family should be included in the configured allow list as it is frequently |
b8afec21 LP |
1697 | used for local communication, including for |
1698 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1699 | logging.</para></listitem> | |
798d3a52 ZJS |
1700 | </varlistentry> |
1701 | ||
1702 | <varlistentry> | |
b8afec21 | 1703 | <term><varname>RestrictNamespaces=</varname></term> |
798d3a52 | 1704 | |
b8afec21 LP |
1705 | <listitem><para>Restricts access to Linux namespace functionality for the processes of this unit. For details |
1706 | about Linux namespaces, see <citerefentry | |
1707 | project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Either | |
1708 | takes a boolean argument, or a space-separated list of namespace type identifiers. If false (the default), no | |
1709 | restrictions on namespace creation and switching are made. If true, access to any kind of namespacing is | |
1710 | prohibited. Otherwise, a space-separated list of namespace type identifiers must be specified, consisting of | |
1711 | any combination of: <constant>cgroup</constant>, <constant>ipc</constant>, <constant>net</constant>, | |
1712 | <constant>mnt</constant>, <constant>pid</constant>, <constant>user</constant> and <constant>uts</constant>. Any | |
1713 | namespace type listed is made accessible to the unit's processes, access to namespace types not listed is | |
6b000af4 | 1714 | prohibited (allow-listing). By prepending the list with a single tilde character (<literal>~</literal>) the |
b8afec21 | 1715 | effect may be inverted: only the listed namespace types will be made inaccessible, all unlisted ones are |
6b000af4 | 1716 | permitted (deny-listing). If the empty string is assigned, the default namespace restrictions are applied, |
53255e53 YW |
1717 | which is equivalent to false. This option may appear more than once, in which case the namespace types are |
1718 | merged by <constant>OR</constant>, or by <constant>AND</constant> if the lines are prefixed with | |
1719 | <literal>~</literal> (see examples below). Internally, this setting limits access to the | |
b8afec21 LP |
1720 | <citerefentry><refentrytitle>unshare</refentrytitle><manvolnum>2</manvolnum></citerefentry>, |
1721 | <citerefentry><refentrytitle>clone</refentrytitle><manvolnum>2</manvolnum></citerefentry> and | |
1722 | <citerefentry><refentrytitle>setns</refentrytitle><manvolnum>2</manvolnum></citerefentry> system calls, taking | |
1723 | the specified flags parameters into account. Note that — if this option is used — in addition to restricting | |
1724 | creation and switching of the specified types of namespaces (or all of them, if true) access to the | |
1725 | <function>setns()</function> system call with a zero flags parameter is prohibited. This setting is only | |
1726 | supported on x86, x86-64, mips, mips-le, mips64, mips64-le, mips64-n32, mips64-le-n32, ppc64, ppc64-le, s390 | |
1727 | and s390x, and enforces no restrictions on other architectures. If running in user mode, or in system mode, but | |
1728 | without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=</varname>), | |
53255e53 YW |
1729 | <varname>NoNewPrivileges=yes</varname> is implied.</para> |
1730 | ||
1731 | <para>Example: if a unit has the following, | |
1732 | <programlisting>RestrictNamespaces=cgroup ipc | |
1733 | RestrictNamespaces=cgroup net</programlisting> | |
1734 | then <constant>cgroup</constant>, <constant>ipc</constant>, and <constant>net</constant> are set. | |
1735 | If the second line is prefixed with <literal>~</literal>, e.g., | |
1736 | <programlisting>RestrictNamespaces=cgroup ipc | |
1737 | RestrictNamespaces=~cgroup net</programlisting> | |
1738 | then, only <constant>ipc</constant> is set.</para></listitem> | |
798d3a52 ZJS |
1739 | </varlistentry> |
1740 | ||
023a4f67 | 1741 | <varlistentry> |
b8afec21 | 1742 | <term><varname>LockPersonality=</varname></term> |
023a4f67 | 1743 | |
b8afec21 LP |
1744 | <listitem><para>Takes a boolean argument. If set, locks down the <citerefentry |
1745 | project='man-pages'><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry> system | |
1746 | call so that the kernel execution domain may not be changed from the default or the personality selected with | |
1747 | <varname>Personality=</varname> directive. This may be useful to improve security, because odd personality | |
1748 | emulations may be poorly tested and source of vulnerabilities. If running in user mode, or in system mode, but | |
1749 | without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=</varname>), | |
1750 | <varname>NoNewPrivileges=yes</varname> is implied.</para></listitem> | |
023a4f67 LP |
1751 | </varlistentry> |
1752 | ||
798d3a52 | 1753 | <varlistentry> |
b8afec21 | 1754 | <term><varname>MemoryDenyWriteExecute=</varname></term> |
798d3a52 | 1755 | |
b8afec21 LP |
1756 | <listitem><para>Takes a boolean argument. If set, attempts to create memory mappings that are writable and |
1757 | executable at the same time, or to change existing memory mappings to become executable, or mapping shared | |
1758 | memory segments as executable are prohibited. Specifically, a system call filter is added that rejects | |
1759 | <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry> system calls with both | |
1760 | <constant>PROT_EXEC</constant> and <constant>PROT_WRITE</constant> set, | |
1761 | <citerefentry><refentrytitle>mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry> or | |
1762 | <citerefentry><refentrytitle>pkey_mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry> system calls | |
1763 | with <constant>PROT_EXEC</constant> set and | |
1764 | <citerefentry><refentrytitle>shmat</refentrytitle><manvolnum>2</manvolnum></citerefentry> system calls with | |
1765 | <constant>SHM_EXEC</constant> set. Note that this option is incompatible with programs and libraries that | |
1766 | generate program code dynamically at runtime, including JIT execution engines, executable stacks, and code | |
1767 | "trampoline" feature of various C compilers. This option improves service security, as it makes harder for | |
10d44e72 TM |
1768 | software exploits to change running code dynamically. However, the protection can be circumvented, if |
1769 | the service can write to a filesystem, which is not mounted with <constant>noexec</constant> (such as | |
1770 | <filename>/dev/shm</filename>), or it can use <function>memfd_create()</function>. This can be | |
1771 | prevented by making such file systems inaccessible to the service | |
1772 | (e.g. <varname>InaccessiblePaths=/dev/shm</varname>) and installing further system call filters | |
1773 | (<varname>SystemCallFilter=~memfd_create</varname>). Note that this feature is fully available on | |
1774 | x86-64, and partially on x86. Specifically, the <function>shmat()</function> protection is not | |
1775 | available on x86. Note that on systems supporting multiple ABIs (such as x86/x86-64) it is | |
1776 | recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the | |
1777 | restrictions of this option. Specifically, it is recommended to combine this option with | |
1778 | <varname>SystemCallArchitectures=native</varname> or similar. If running in user mode, or in system | |
1779 | mode, but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting | |
1780 | <varname>User=</varname>), <varname>NoNewPrivileges=yes</varname> is implied.</para></listitem> | |
798d3a52 ZJS |
1781 | </varlistentry> |
1782 | ||
1783 | <varlistentry> | |
b8afec21 | 1784 | <term><varname>RestrictRealtime=</varname></term> |
798d3a52 | 1785 | |
b8afec21 LP |
1786 | <listitem><para>Takes a boolean argument. If set, any attempts to enable realtime scheduling in a process of |
1787 | the unit are refused. This restricts access to realtime task scheduling policies such as | |
1788 | <constant>SCHED_FIFO</constant>, <constant>SCHED_RR</constant> or <constant>SCHED_DEADLINE</constant>. See | |
1789 | <citerefentry project='man-pages'><refentrytitle>sched</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
1790 | for details about these scheduling policies. If running in user mode, or in system mode, but without the | |
1791 | <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=</varname>), | |
1792 | <varname>NoNewPrivileges=yes</varname> is implied. Realtime scheduling policies may be used to monopolize CPU | |
1793 | time for longer periods of time, and may hence be used to lock up or otherwise trigger Denial-of-Service | |
1794 | situations on the system. It is hence recommended to restrict access to realtime scheduling to the few programs | |
1795 | that actually require them. Defaults to off.</para></listitem> | |
798d3a52 ZJS |
1796 | </varlistentry> |
1797 | ||
7445db6e LP |
1798 | <varlistentry> |
1799 | <term><varname>RestrictSUIDSGID=</varname></term> | |
1800 | ||
1801 | <listitem><para>Takes a boolean argument. If set, any attempts to set the set-user-ID (SUID) or | |
1802 | set-group-ID (SGID) bits on files or directories will be denied (for details on these bits see | |
1803 | <citerefentry | |
1804 | project='man-pages'><refentrytitle>inode</refentrytitle><manvolnum>7</manvolnum></citerefentry>). If | |
1805 | running in user mode, or in system mode, but without the <constant>CAP_SYS_ADMIN</constant> | |
1806 | capability (e.g. setting <varname>User=</varname>), <varname>NoNewPrivileges=yes</varname> is | |
1807 | implied. As the SUID/SGID bits are mechanisms to elevate privileges, and allows users to acquire the | |
1808 | identity of other users, it is recommended to restrict creation of SUID/SGID files to the few | |
1809 | programs that actually require them. Note that this restricts marking of any type of file system | |
1810 | object with these bits, including both regular files and directories (where the SGID is a different | |
bf65b7e0 LP |
1811 | meaning than for files, see documentation). This option is implied if <varname>DynamicUser=</varname> |
1812 | is enabled. Defaults to off.</para></listitem> | |
7445db6e LP |
1813 | </varlistentry> |
1814 | ||
798d3a52 | 1815 | <varlistentry> |
b8afec21 | 1816 | <term><varname>RemoveIPC=</varname></term> |
798d3a52 | 1817 | |
b8afec21 LP |
1818 | <listitem><para>Takes a boolean parameter. If set, all System V and POSIX IPC objects owned by the user and |
1819 | group the processes of this unit are run as are removed when the unit is stopped. This setting only has an | |
1820 | effect if at least one of <varname>User=</varname>, <varname>Group=</varname> and | |
1821 | <varname>DynamicUser=</varname> are used. It has no effect on IPC objects owned by the root user. Specifically, | |
1822 | this removes System V semaphores, as well as System V and POSIX shared memory segments and message queues. If | |
1823 | multiple units use the same user or group the IPC objects are removed when the last of these units is | |
c4d4b5a7 LP |
1824 | stopped. This setting is implied if <varname>DynamicUser=</varname> is set.</para> |
1825 | ||
1826 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1827 | </varlistentry> |
1828 | ||
2f2e14b2 LP |
1829 | <varlistentry> |
1830 | <term><varname>PrivateMounts=</varname></term> | |
1831 | ||
1832 | <listitem><para>Takes a boolean parameter. If set, the processes of this unit will be run in their own private | |
1833 | file system (mount) namespace with all mount propagation from the processes towards the host's main file system | |
1834 | namespace turned off. This means any file system mount points established or removed by the unit's processes | |
1835 | will be private to them and not be visible to the host. However, file system mount points established or | |
1836 | removed on the host will be propagated to the unit's processes. See <citerefentry | |
1837 | project='man-pages'><refentrytitle>mount_namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
1838 | details on file system namespaces. Defaults to off.</para> | |
1839 | ||
1840 | <para>When turned on, this executes three operations for each invoked process: a new | |
1841 | <constant>CLONE_NEWNS</constant> namespace is created, after which all existing mounts are remounted to | |
1842 | <constant>MS_SLAVE</constant> to disable propagation from the unit's processes to the host (but leaving | |
1843 | propagation in the opposite direction in effect). Finally, the mounts are remounted again to the propagation | |
1844 | mode configured with <varname>MountFlags=</varname>, see below.</para> | |
1845 | ||
1846 | <para>File system namespaces are set up individually for each process forked off by the service manager. Mounts | |
1847 | established in the namespace of the process created by <varname>ExecStartPre=</varname> will hence be cleaned | |
1848 | up automatically as soon as that process exits and will not be available to subsequent processes forked off for | |
1849 | <varname>ExecStart=</varname> (and similar applies to the various other commands configured for | |
1850 | units). Similarly, <varname>JoinsNamespaceOf=</varname> does not permit sharing kernel mount namespaces between | |
1851 | units, it only enables sharing of the <filename>/tmp/</filename> and <filename>/var/tmp/</filename> | |
1852 | directories.</para> | |
1853 | ||
1854 | <para>Other file system namespace unit settings — <varname>PrivateMounts=</varname>, | |
1855 | <varname>PrivateTmp=</varname>, <varname>PrivateDevices=</varname>, <varname>ProtectSystem=</varname>, | |
1856 | <varname>ProtectHome=</varname>, <varname>ReadOnlyPaths=</varname>, <varname>InaccessiblePaths=</varname>, | |
1857 | <varname>ReadWritePaths=</varname>, … — also enable file system namespacing in a fashion equivalent to this | |
1858 | option. Hence it is primarily useful to explicitly request this behaviour if none of the other settings are | |
c4d4b5a7 LP |
1859 | used.</para> |
1860 | ||
1861 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
2f2e14b2 LP |
1862 | </varlistentry> |
1863 | ||
798d3a52 | 1864 | <varlistentry> |
b8afec21 | 1865 | <term><varname>MountFlags=</varname></term> |
798d3a52 | 1866 | |
2f2e14b2 LP |
1867 | <listitem><para>Takes a mount propagation setting: <option>shared</option>, <option>slave</option> or |
1868 | <option>private</option>, which controls whether file system mount points in the file system namespaces set up | |
1869 | for this unit's processes will receive or propagate mounts and unmounts from other file system namespaces. See | |
1870 | <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1871 | for details on mount propagation, and the three propagation flags in particular.</para> | |
1872 | ||
1873 | <para>This setting only controls the <emphasis>final</emphasis> propagation setting in effect on all mount | |
1874 | points of the file system namespace created for each process of this unit. Other file system namespacing unit | |
1875 | settings (see the discussion in <varname>PrivateMounts=</varname> above) will implicitly disable mount and | |
1876 | unmount propagation from the unit's processes towards the host by changing the propagation setting of all mount | |
86b52a39 | 1877 | points in the unit's file system namespace to <option>slave</option> first. Setting this option to |
923f9101 | 1878 | <option>shared</option> does not reestablish propagation in that case.</para> |
2f2e14b2 LP |
1879 | |
1880 | <para>If not set – but file system namespaces are enabled through another file system namespace unit setting – | |
1881 | <option>shared</option> mount propagation is used, but — as mentioned — as <option>slave</option> is applied | |
1882 | first, propagation from the unit's processes to the host is still turned off.</para> | |
1883 | ||
cd990847 | 1884 | <para>It is not recommended to use <option>private</option> mount propagation for units, as this means |
2f2e14b2 LP |
1885 | temporary mounts (such as removable media) of the host will stay mounted and thus indefinitely busy in forked |
1886 | off processes, as unmount propagation events won't be received by the file system namespace of the unit.</para> | |
1887 | ||
1888 | <para>Usually, it is best to leave this setting unmodified, and use higher level file system namespacing | |
1889 | options instead, in particular <varname>PrivateMounts=</varname>, see above.</para> | |
c4d4b5a7 LP |
1890 | |
1891 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
798d3a52 ZJS |
1892 | </varlistentry> |
1893 | ||
b8afec21 LP |
1894 | </variablelist> |
1895 | </refsect1> | |
a6fabe38 | 1896 | |
b8afec21 LP |
1897 | <refsect1> |
1898 | <title>System Call Filtering</title> | |
e0e2ecd5 | 1899 | <variablelist class='unit-directives'> |
798d3a52 ZJS |
1900 | |
1901 | <varlistentry> | |
1902 | <term><varname>SystemCallFilter=</varname></term> | |
1903 | ||
330703fb LP |
1904 | <listitem><para>Takes a space-separated list of system call names. If this setting is used, all |
1905 | system calls executed by the unit processes except for the listed ones will result in immediate | |
6b000af4 | 1906 | process termination with the <constant>SIGSYS</constant> signal (allow-listing). (See |
330703fb LP |
1907 | <varname>SystemCallErrorNumber=</varname> below for changing the default action). If the first |
1908 | character of the list is <literal>~</literal>, the effect is inverted: only the listed system calls | |
6b000af4 | 1909 | will result in immediate process termination (deny-listing). Deny-listed system calls and system call |
330703fb LP |
1910 | groups may optionally be suffixed with a colon (<literal>:</literal>) and <literal>errno</literal> |
1911 | error number (between 0 and 4095) or errno name such as <constant>EPERM</constant>, | |
1912 | <constant>EACCES</constant> or <constant>EUCLEAN</constant> (see <citerefentry | |
1913 | project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> for a | |
6b000af4 | 1914 | full list). This value will be returned when a deny-listed system call is triggered, instead of |
005bfaf1 TM |
1915 | terminating the processes immediately. Special setting <literal>kill</literal> can be used to |
1916 | explicitly specify killing. This value takes precedence over the one given in | |
330703fb LP |
1917 | <varname>SystemCallErrorNumber=</varname>, see below. If running in user mode, or in system mode, |
1918 | but without the <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting | |
1919 | <varname>User=nobody</varname>), <varname>NoNewPrivileges=yes</varname> is implied. This feature | |
1920 | makes use of the Secure Computing Mode 2 interfaces of the kernel ('seccomp filtering') and is useful | |
725d9713 YW |
1921 | for enforcing a minimal sandboxing environment. Note that the <function>execve()</function>, |
1922 | <function>exit()</function>, <function>exit_group()</function>, <function>getrlimit()</function>, | |
1923 | <function>rt_sigreturn()</function>, <function>sigreturn()</function> system calls and the system calls | |
6b000af4 | 1924 | for querying time and sleeping are implicitly allow-listed and do not need to be listed |
330703fb LP |
1925 | explicitly. This option may be specified more than once, in which case the filter masks are |
1926 | merged. If the empty string is assigned, the filter is reset, all prior assignments will have no | |
1927 | effect. This does not affect commands prefixed with <literal>+</literal>.</para> | |
798d3a52 | 1928 | |
0b8fab97 LP |
1929 | <para>Note that on systems supporting multiple ABIs (such as x86/x86-64) it is recommended to turn off |
1930 | alternative ABIs for services, so that they cannot be used to circumvent the restrictions of this | |
1931 | option. Specifically, it is recommended to combine this option with | |
1932 | <varname>SystemCallArchitectures=native</varname> or similar.</para> | |
1933 | ||
2ca8dc15 | 1934 | <para>Note that strict system call filters may impact execution and error handling code paths of the service |
725d9713 | 1935 | invocation. Specifically, access to the <function>execve()</function> system call is required for the execution |
2ca8dc15 LP |
1936 | of the service binary — if it is blocked service invocation will necessarily fail. Also, if execution of the |
1937 | service binary fails for some reason (for example: missing service executable), the error handling logic might | |
1938 | require access to an additional set of system calls in order to process and log this failure correctly. It | |
1939 | might be necessary to temporarily disable system call filters in order to simplify debugging of such | |
1940 | failures.</para> | |
1941 | ||
6b000af4 LP |
1942 | <para>If you specify both types of this option (i.e. allow-listing and deny-listing), the first |
1943 | encountered will take precedence and will dictate the default action (termination or approval of a | |
1944 | system call). Then the next occurrences of this option will add or delete the listed system calls | |
1945 | from the set of the filtered system calls, depending of its type and the default action. (For | |
725d9713 YW |
1946 | example, if you have started with an allow list rule for <function>read()</function> and |
1947 | <function>write()</function>, and right after it add a deny list rule for <function>write()</function>, | |
1948 | then <function>write()</function> will be removed from the set.)</para> | |
b8afec21 LP |
1949 | |
1950 | <para>As the number of possible system calls is large, predefined sets of system calls are provided. A set | |
1951 | starts with <literal>@</literal> character, followed by name of the set. | |
201c1cc2 TM |
1952 | |
1953 | <table> | |
1954 | <title>Currently predefined system call sets</title> | |
1955 | ||
1956 | <tgroup cols='2'> | |
1957 | <colspec colname='set' /> | |
1958 | <colspec colname='description' /> | |
1959 | <thead> | |
1960 | <row> | |
1961 | <entry>Set</entry> | |
1962 | <entry>Description</entry> | |
1963 | </row> | |
1964 | </thead> | |
1965 | <tbody> | |
44898c53 LP |
1966 | <row> |
1967 | <entry>@aio</entry> | |
1968 | <entry>Asynchronous I/O (<citerefentry project='man-pages'><refentrytitle>io_setup</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>io_submit</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> | |
1969 | </row> | |
133ddbbe LP |
1970 | <row> |
1971 | <entry>@basic-io</entry> | |
1972 | <entry>System calls for basic I/O: reading, writing, seeking, file descriptor duplication and closing (<citerefentry project='man-pages'><refentrytitle>read</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>write</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> | |
1973 | </row> | |
44898c53 LP |
1974 | <row> |
1975 | <entry>@chown</entry> | |
1976 | <entry>Changing file ownership (<citerefentry project='man-pages'><refentrytitle>chown</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>fchownat</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> | |
1977 | </row> | |
201c1cc2 TM |
1978 | <row> |
1979 | <entry>@clock</entry> | |
1f9ac68b LP |
1980 | <entry>System calls for changing the system clock (<citerefentry project='man-pages'><refentrytitle>adjtimex</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>settimeofday</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> |
1981 | </row> | |
1982 | <row> | |
1983 | <entry>@cpu-emulation</entry> | |
1984 | <entry>System calls for CPU emulation functionality (<citerefentry project='man-pages'><refentrytitle>vm86</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
1985 | </row> | |
1986 | <row> | |
1987 | <entry>@debug</entry> | |
1988 | <entry>Debugging, performance monitoring and tracing functionality (<citerefentry project='man-pages'><refentrytitle>ptrace</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>perf_event_open</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
201c1cc2 | 1989 | </row> |
1a1b13c9 LP |
1990 | <row> |
1991 | <entry>@file-system</entry> | |
e9dd6984 | 1992 | <entry>File system operations: opening, creating files and directories for read and write, renaming and removing them, reading file properties, or creating hard and symbolic links</entry> |
1a1b13c9 | 1993 | </row> |
201c1cc2 TM |
1994 | <row> |
1995 | <entry>@io-event</entry> | |
1f9ac68b | 1996 | <entry>Event loop system calls (<citerefentry project='man-pages'><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>select</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>eventfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> |
201c1cc2 TM |
1997 | </row> |
1998 | <row> | |
1999 | <entry>@ipc</entry> | |
cd5bfd7e | 2000 | <entry>Pipes, SysV IPC, POSIX Message Queues and other IPC (<citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>svipc</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry> |
1f9ac68b LP |
2001 | </row> |
2002 | <row> | |
2003 | <entry>@keyring</entry> | |
2004 | <entry>Kernel keyring access (<citerefentry project='man-pages'><refentrytitle>keyctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
201c1cc2 | 2005 | </row> |
cd0ddf6f LP |
2006 | <row> |
2007 | <entry>@memlock</entry> | |
e9dd6984 | 2008 | <entry>Locking of memory in RAM (<citerefentry project='man-pages'><refentrytitle>mlock</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>mlockall</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> |
cd0ddf6f | 2009 | </row> |
201c1cc2 TM |
2010 | <row> |
2011 | <entry>@module</entry> | |
d5efc18b | 2012 | <entry>Loading and unloading of kernel modules (<citerefentry project='man-pages'><refentrytitle>init_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>delete_module</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> |
201c1cc2 TM |
2013 | </row> |
2014 | <row> | |
2015 | <entry>@mount</entry> | |
d5efc18b | 2016 | <entry>Mounting and unmounting of file systems (<citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> |
201c1cc2 TM |
2017 | </row> |
2018 | <row> | |
2019 | <entry>@network-io</entry> | |
1f9ac68b | 2020 | <entry>Socket I/O (including local AF_UNIX): <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry></entry> |
201c1cc2 TM |
2021 | </row> |
2022 | <row> | |
2023 | <entry>@obsolete</entry> | |
1f9ac68b | 2024 | <entry>Unusual, obsolete or unimplemented (<citerefentry project='man-pages'><refentrytitle>create_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>gtty</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> |
201c1cc2 TM |
2025 | </row> |
2026 | <row> | |
2027 | <entry>@privileged</entry> | |
1f9ac68b | 2028 | <entry>All system calls which need super-user capabilities (<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry> |
201c1cc2 TM |
2029 | </row> |
2030 | <row> | |
2031 | <entry>@process</entry> | |
5e2b0e1c | 2032 | <entry>Process control, execution, namespacing operations (<citerefentry project='man-pages'><refentrytitle>clone</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>, …)</entry> |
201c1cc2 TM |
2033 | </row> |
2034 | <row> | |
2035 | <entry>@raw-io</entry> | |
aa6b9cec | 2036 | <entry>Raw I/O port access (<citerefentry project='man-pages'><refentrytitle>ioperm</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>iopl</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <function>pciconfig_read()</function>, …)</entry> |
201c1cc2 | 2037 | </row> |
bd2ab3f4 LP |
2038 | <row> |
2039 | <entry>@reboot</entry> | |
2040 | <entry>System calls for rebooting and reboot preparation (<citerefentry project='man-pages'><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <function>kexec()</function>, …)</entry> | |
2041 | </row> | |
133ddbbe LP |
2042 | <row> |
2043 | <entry>@resources</entry> | |
2044 | <entry>System calls for changing resource limits, memory and scheduling parameters (<citerefentry project='man-pages'><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> | |
2045 | </row> | |
6eaaeee9 LP |
2046 | <row> |
2047 | <entry>@setuid</entry> | |
2048 | <entry>System calls for changing user ID and group ID credentials, (<citerefentry project='man-pages'><refentrytitle>setuid</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>setgid</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>setresuid</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> | |
2049 | </row> | |
cd0ddf6f LP |
2050 | <row> |
2051 | <entry>@signal</entry> | |
2052 | <entry>System calls for manipulating and handling process signals (<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> | |
2053 | </row> | |
bd2ab3f4 LP |
2054 | <row> |
2055 | <entry>@swap</entry> | |
2056 | <entry>System calls for enabling/disabling swap devices (<citerefentry project='man-pages'><refentrytitle>swapon</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>swapoff</refentrytitle><manvolnum>2</manvolnum></citerefentry>)</entry> | |
2057 | </row> | |
44898c53 LP |
2058 | <row> |
2059 | <entry>@sync</entry> | |
e9dd6984 | 2060 | <entry>Synchronizing files and memory to disk (<citerefentry project='man-pages'><refentrytitle>fsync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>msync</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> |
44898c53 | 2061 | </row> |
70526841 LP |
2062 | <row> |
2063 | <entry>@system-service</entry> | |
6b000af4 | 2064 | <entry>A reasonable set of system calls used by common system services, excluding any special purpose calls. This is the recommended starting point for allow-listing system calls for system services, as it contains what is typically needed by system services, but excludes overly specific interfaces. For example, the following APIs are excluded: <literal>@clock</literal>, <literal>@mount</literal>, <literal>@swap</literal>, <literal>@reboot</literal>.</entry> |
70526841 | 2065 | </row> |
cd0ddf6f LP |
2066 | <row> |
2067 | <entry>@timer</entry> | |
2068 | <entry>System calls for scheduling operations by time (<citerefentry project='man-pages'><refentrytitle>alarm</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>timer_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> | |
2069 | </row> | |
95aac012 ZJS |
2070 | <row> |
2071 | <entry>@known</entry> | |
6f5cf880 | 2072 | <entry>All system calls defined by the kernel. This list is defined statically in systemd based on a kernel version that was available when this systemd version was released. It will become progressively more out-of-date as the kernel is updated.</entry> |
95aac012 | 2073 | </row> |
201c1cc2 TM |
2074 | </tbody> |
2075 | </tgroup> | |
2076 | </table> | |
2077 | ||
b8afec21 LP |
2078 | Note, that as new system calls are added to the kernel, additional system calls might be added to the groups |
2079 | above. Contents of the sets may also change between systemd versions. In addition, the list of system calls | |
2080 | depends on the kernel version and architecture for which systemd was compiled. Use | |
2081 | <command>systemd-analyze syscall-filter</command> to list the actual list of system calls in each | |
2082 | filter.</para> | |
effbd6d2 | 2083 | |
6b000af4 LP |
2084 | <para>Generally, allow-listing system calls (rather than deny-listing) is the safer mode of |
2085 | operation. It is recommended to enforce system call allow lists for all long-running system | |
2086 | services. Specifically, the following lines are a relatively safe basic choice for the majority of | |
2087 | system services:</para> | |
70526841 LP |
2088 | |
2089 | <programlisting>[Service] | |
2090 | SystemCallFilter=@system-service | |
2091 | SystemCallErrorNumber=EPERM</programlisting> | |
2092 | ||
330703fb LP |
2093 | <para>Note that various kernel system calls are defined redundantly: there are multiple system calls |
2094 | for executing the same operation. For example, the <function>pidfd_send_signal()</function> system | |
2095 | call may be used to execute operations similar to what can be done with the older | |
2096 | <function>kill()</function> system call, hence blocking the latter without the former only provides | |
2097 | weak protection. Since new system calls are added regularly to the kernel as development progresses, | |
6b000af4 LP |
2098 | keeping system call deny lists comprehensive requires constant work. It is thus recommended to use |
2099 | allow-listing instead, which offers the benefit that new system calls are by default implicitly | |
2100 | blocked until the allow list is updated.</para> | |
330703fb LP |
2101 | |
2102 | <para>Also note that a number of system calls are required to be accessible for the dynamic linker to | |
2103 | work. The dynamic linker is required for running most regular programs (specifically: all dynamic ELF | |
2104 | binaries, which is how most distributions build packaged programs). This means that blocking these | |
2105 | system calls (which include <function>open()</function>, <function>openat()</function> or | |
2106 | <function>mmap()</function>) will make most programs typically shipped with generic distributions | |
2107 | unusable.</para> | |
2108 | ||
effbd6d2 LP |
2109 | <para>It is recommended to combine the file system namespacing related options with |
2110 | <varname>SystemCallFilter=~@mount</varname>, in order to prohibit the unit's processes to undo the | |
2111 | mappings. Specifically these are the options <varname>PrivateTmp=</varname>, | |
2112 | <varname>PrivateDevices=</varname>, <varname>ProtectSystem=</varname>, <varname>ProtectHome=</varname>, | |
2113 | <varname>ProtectKernelTunables=</varname>, <varname>ProtectControlGroups=</varname>, | |
022d3345 | 2114 | <varname>ProtectKernelLogs=</varname>, <varname>ProtectClock=</varname>, <varname>ReadOnlyPaths=</varname>, |
d916e35b | 2115 | <varname>InaccessiblePaths=</varname> and <varname>ReadWritePaths=</varname>.</para></listitem> |
798d3a52 ZJS |
2116 | </varlistentry> |
2117 | ||
2118 | <varlistentry> | |
2119 | <term><varname>SystemCallErrorNumber=</varname></term> | |
2120 | ||
330703fb LP |
2121 | <listitem><para>Takes an <literal>errno</literal> error number (between 1 and 4095) or errno name |
2122 | such as <constant>EPERM</constant>, <constant>EACCES</constant> or <constant>EUCLEAN</constant>, to | |
2123 | return when the system call filter configured with <varname>SystemCallFilter=</varname> is triggered, | |
2124 | instead of terminating the process immediately. See <citerefentry | |
2125 | project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> for a | |
005bfaf1 TM |
2126 | full list of error codes. When this setting is not used, or when the empty string or the special |
2127 | setting <literal>kill</literal> is assigned, the process will be terminated immediately when the | |
2128 | filter is triggered.</para></listitem> | |
798d3a52 ZJS |
2129 | </varlistentry> |
2130 | ||
2131 | <varlistentry> | |
2132 | <term><varname>SystemCallArchitectures=</varname></term> | |
2133 | ||
0b8fab97 LP |
2134 | <listitem><para>Takes a space-separated list of architecture identifiers to include in the system call |
2135 | filter. The known architecture identifiers are the same as for <varname>ConditionArchitecture=</varname> | |
2136 | described in <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
2137 | as well as <constant>x32</constant>, <constant>mips64-n32</constant>, <constant>mips64-le-n32</constant>, and | |
2428aaf8 | 2138 | the special identifier <constant>native</constant>. The special identifier <constant>native</constant> |
62a0680b AJ |
2139 | implicitly maps to the native architecture of the system (or more precisely: to the architecture the system |
2140 | manager is compiled for). If running in user mode, or in system mode, but without the | |
2141 | <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=nobody</varname>), | |
2142 | <varname>NoNewPrivileges=yes</varname> is implied. By default, this option is set to the empty list, i.e. no | |
e9dd6984 | 2143 | filtering is applied.</para> |
0b8fab97 | 2144 | |
2428aaf8 AJ |
2145 | <para>If this setting is used, processes of this unit will only be permitted to call native system calls, and |
2146 | system calls of the specified architectures. For the purposes of this option, the x32 architecture is treated | |
2147 | as including x86-64 system calls. However, this setting still fulfills its purpose, as explained below, on | |
2148 | x32.</para> | |
2149 | ||
2150 | <para>System call filtering is not equally effective on all architectures. For example, on x86 | |
0b8fab97 LP |
2151 | filtering of network socket-related calls is not possible, due to ABI limitations — a limitation that x86-64 |
2152 | does not have, however. On systems supporting multiple ABIs at the same time — such as x86/x86-64 — it is hence | |
2153 | recommended to limit the set of permitted system call architectures so that secondary ABIs may not be used to | |
2154 | circumvent the restrictions applied to the native ABI of the system. In particular, setting | |
c29ebc1a | 2155 | <varname>SystemCallArchitectures=native</varname> is a good choice for disabling non-native ABIs.</para> |
0b8fab97 | 2156 | |
b8afec21 LP |
2157 | <para>System call architectures may also be restricted system-wide via the |
2158 | <varname>SystemCallArchitectures=</varname> option in the global configuration. See | |
2159 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for | |
2160 | details.</para></listitem> | |
2161 | </varlistentry> | |
2162 | ||
9df2cdd8 TM |
2163 | <varlistentry> |
2164 | <term><varname>SystemCallLog=</varname></term> | |
2165 | ||
2166 | <listitem><para>Takes a space-separated list of system call names. If this setting is used, all | |
2167 | system calls executed by the unit processes for the listed ones will be logged. If the first | |
2168 | character of the list is <literal>~</literal>, the effect is inverted: all system calls except the | |
2169 | listed system calls will be logged. If running in user mode, or in system mode, but without the | |
2170 | <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting <varname>User=nobody</varname>), | |
2171 | <varname>NoNewPrivileges=yes</varname> is implied. This feature makes use of the Secure Computing | |
2172 | Mode 2 interfaces of the kernel ('seccomp filtering') and is useful for auditing or setting up a | |
2173 | minimal sandboxing environment. This option may be specified more than once, in which case the filter | |
2174 | masks are merged. If the empty string is assigned, the filter is reset, all prior assignments will | |
2175 | have no effect. This does not affect commands prefixed with <literal>+</literal>.</para></listitem> | |
2176 | </varlistentry> | |
2177 | ||
b8afec21 LP |
2178 | </variablelist> |
2179 | </refsect1> | |
2180 | ||
2181 | <refsect1> | |
2182 | <title>Environment</title> | |
2183 | ||
e0e2ecd5 | 2184 | <variablelist class='unit-directives'> |
b8afec21 LP |
2185 | |
2186 | <varlistentry> | |
2187 | <term><varname>Environment=</varname></term> | |
2188 | ||
0dc9fd56 ZJS |
2189 | <listitem><para>Sets environment variables for executed processes. Takes a space-separated list of |
2190 | variable assignments. This option may be specified more than once, in which case all listed variables | |
2191 | will be set. If the same variable is set twice, the later setting will override the earlier | |
2192 | setting. If the empty string is assigned to this option, the list of environment variables is reset, | |
2193 | all prior assignments have no effect. Variable expansion is not performed inside the strings, | |
2194 | however, specifier expansion is possible. The <literal>$</literal> character has no special | |
2195 | meaning. If you need to assign a value containing spaces or the equals sign to a variable, use double | |
2196 | quotes (") for the assignment.</para> | |
2197 | ||
2198 | <para>The names of the variables can contain ASCII letters, digits, and the underscore | |
2199 | character. Variable names cannot be empty or start with a digit. In variable values, most characters | |
2200 | are allowed, but non-printable characters are currently rejected.</para> | |
b8afec21 LP |
2201 | |
2202 | <para>Example: | |
2203 | <programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</programlisting> | |
2204 | gives three variables <literal>VAR1</literal>, | |
2205 | <literal>VAR2</literal>, <literal>VAR3</literal> | |
2206 | with the values <literal>word1 word2</literal>, | |
2207 | <literal>word3</literal>, <literal>$word 5 6</literal>. | |
2208 | </para> | |
2209 | ||
2210 | <para> | |
2211 | See <citerefentry | |
2212 | project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details | |
438311a5 LP |
2213 | about environment variables.</para> |
2214 | ||
3220cf39 LP |
2215 | <para>Note that environment variables are not suitable for passing secrets (such as passwords, key |
2216 | material, …) to service processes. Environment variables set for a unit are exposed to unprivileged | |
2217 | clients via D-Bus IPC, and generally not understood as being data that requires protection. Moreover, | |
2218 | environment variables are propagated down the process tree, including across security boundaries | |
2219 | (such as setuid/setgid executables), and hence might leak to processes that should not have access to | |
2220 | the secret data. Use <varname>LoadCredential=</varname> (see below) to pass data to unit processes | |
2221 | securely.</para></listitem> | |
b8afec21 LP |
2222 | </varlistentry> |
2223 | ||
2224 | <varlistentry> | |
2225 | <term><varname>EnvironmentFile=</varname></term> | |
2226 | ||
2227 | <listitem><para>Similar to <varname>Environment=</varname> but reads the environment variables from a text | |
2228 | file. The text file should contain new-line-separated variable assignments. Empty lines, lines without an | |
2229 | <literal>=</literal> separator, or lines starting with ; or # will be ignored, which may be used for | |
2230 | commenting. A line ending with a backslash will be concatenated with the following one, allowing multiline | |
2231 | variable definitions. The parser strips leading and trailing whitespace from the values of assignments, unless | |
2232 | you use double quotes (").</para> | |
2233 | ||
69bdb3b1 MS |
2234 | <para><ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C escapes</ulink> |
2235 | are supported, but not | |
2236 | <ulink url="https://en.wikipedia.org/wiki/Control_character#In_ASCII">most control characters</ulink>. | |
2237 | <literal>\t</literal> and <literal>\n</literal> can be used to insert tabs and newlines within | |
2238 | <varname>EnvironmentFile=</varname>.</para> | |
2239 | ||
b8afec21 LP |
2240 | <para>The argument passed should be an absolute filename or wildcard expression, optionally prefixed with |
2241 | <literal>-</literal>, which indicates that if the file does not exist, it will not be read and no error or | |
2242 | warning message is logged. This option may be specified more than once in which case all specified files are | |
2243 | read. If the empty string is assigned to this option, the list of file to read is reset, all prior assignments | |
2244 | have no effect.</para> | |
2245 | ||
2246 | <para>The files listed with this directive will be read shortly before the process is executed (more | |
2247 | specifically, after all processes from a previous unit state terminated. This means you can generate these | |
412a6c64 TM |
2248 | files in one unit state, and read it with this option in the next. The files are read from the file |
2249 | system of the service manager, before any file system changes like bind mounts take place).</para> | |
b8afec21 LP |
2250 | |
2251 | <para>Settings from these files override settings made with <varname>Environment=</varname>. If the same | |
2252 | variable is set twice from these files, the files will be read in the order they are specified and the later | |
2253 | setting will override the earlier setting.</para></listitem> | |
2254 | </varlistentry> | |
2255 | ||
2256 | <varlistentry> | |
2257 | <term><varname>PassEnvironment=</varname></term> | |
2258 | ||
2259 | <listitem><para>Pass environment variables set for the system service manager to executed processes. Takes a | |
2260 | space-separated list of variable names. This option may be specified more than once, in which case all listed | |
2261 | variables will be passed. If the empty string is assigned to this option, the list of environment variables to | |
2262 | pass is reset, all prior assignments have no effect. Variables specified that are not set for the system | |
2263 | manager will not be passed and will be silently ignored. Note that this option is only relevant for the system | |
2264 | service manager, as system services by default do not automatically inherit any environment variables set for | |
2265 | the service manager itself. However, in case of the user service manager all environment variables are passed | |
2266 | to the executed processes anyway, hence this option is without effect for the user service manager.</para> | |
2267 | ||
2268 | <para>Variables set for invoked processes due to this setting are subject to being overridden by those | |
2269 | configured with <varname>Environment=</varname> or <varname>EnvironmentFile=</varname>.</para> | |
2270 | ||
69bdb3b1 MS |
2271 | <para><ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C escapes</ulink> |
2272 | are supported, but not | |
2273 | <ulink url="https://en.wikipedia.org/wiki/Control_character#In_ASCII">most control characters</ulink>. | |
2274 | <literal>\t</literal> and <literal>\n</literal> can be used to insert tabs and newlines within | |
2275 | <varname>EnvironmentFile=</varname>.</para> | |
2276 | ||
b8afec21 LP |
2277 | <para>Example: |
2278 | <programlisting>PassEnvironment=VAR1 VAR2 VAR3</programlisting> | |
2279 | passes three variables <literal>VAR1</literal>, | |
2280 | <literal>VAR2</literal>, <literal>VAR3</literal> | |
2281 | with the values set for those variables in PID1.</para> | |
2282 | ||
2283 | <para> | |
2284 | See <citerefentry | |
2285 | project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details | |
2286 | about environment variables.</para></listitem> | |
2287 | </varlistentry> | |
2288 | ||
2289 | <varlistentry> | |
2290 | <term><varname>UnsetEnvironment=</varname></term> | |
2291 | ||
2292 | <listitem><para>Explicitly unset environment variable assignments that would normally be passed from the | |
2293 | service manager to invoked processes of this unit. Takes a space-separated list of variable names or variable | |
2294 | assignments. This option may be specified more than once, in which case all listed variables/assignments will | |
2295 | be unset. If the empty string is assigned to this option, the list of environment variables/assignments to | |
2296 | unset is reset. If a variable assignment is specified (that is: a variable name, followed by | |
2297 | <literal>=</literal>, followed by its value), then any environment variable matching this precise assignment is | |
2298 | removed. If a variable name is specified (that is a variable name without any following <literal>=</literal> or | |
2299 | value), then any assignment matching the variable name, regardless of its value is removed. Note that the | |
2300 | effect of <varname>UnsetEnvironment=</varname> is applied as final step when the environment list passed to | |
2301 | executed processes is compiled. That means it may undo assignments from any configuration source, including | |
2302 | assignments made through <varname>Environment=</varname> or <varname>EnvironmentFile=</varname>, inherited from | |
2303 | the system manager's global set of environment variables, inherited via <varname>PassEnvironment=</varname>, | |
2304 | set by the service manager itself (such as <varname>$NOTIFY_SOCKET</varname> and such), or set by a PAM module | |
2305 | (in case <varname>PAMName=</varname> is used).</para> | |
2306 | ||
82651d5b ZJS |
2307 | <para>See "Environment Variables in Spawned Processes" below for a description of how those |
2308 | settings combine to form the inherited environment. See <citerefentry | |
2309 | project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for general | |
2310 | information about environment variables.</para></listitem> | |
b8afec21 LP |
2311 | </varlistentry> |
2312 | ||
2313 | </variablelist> | |
2314 | </refsect1> | |
2315 | ||
2316 | <refsect1> | |
2317 | <title>Logging and Standard Input/Output</title> | |
2318 | ||
e0e2ecd5 | 2319 | <variablelist class='unit-directives'> |
b8afec21 LP |
2320 | <varlistentry> |
2321 | ||
2322 | <term><varname>StandardInput=</varname></term> | |
2323 | ||
2324 | <listitem><para>Controls where file descriptor 0 (STDIN) of the executed processes is connected to. Takes one | |
2325 | of <option>null</option>, <option>tty</option>, <option>tty-force</option>, <option>tty-fail</option>, | |
2326 | <option>data</option>, <option>file:<replaceable>path</replaceable></option>, <option>socket</option> or | |
2327 | <option>fd:<replaceable>name</replaceable></option>.</para> | |
2328 | ||
2329 | <para>If <option>null</option> is selected, standard input will be connected to <filename>/dev/null</filename>, | |
2330 | i.e. all read attempts by the process will result in immediate EOF.</para> | |
2331 | ||
2332 | <para>If <option>tty</option> is selected, standard input is connected to a TTY (as configured by | |
2333 | <varname>TTYPath=</varname>, see below) and the executed process becomes the controlling process of the | |
2334 | terminal. If the terminal is already being controlled by another process, the executed process waits until the | |
2335 | current controlling process releases the terminal.</para> | |
2336 | ||
2337 | <para><option>tty-force</option> is similar to <option>tty</option>, but the executed process is forcefully and | |
2338 | immediately made the controlling process of the terminal, potentially removing previous controlling processes | |
2339 | from the terminal.</para> | |
2340 | ||
2341 | <para><option>tty-fail</option> is similar to <option>tty</option>, but if the terminal already has a | |
2342 | controlling process start-up of the executed process fails.</para> | |
2343 | ||
2344 | <para>The <option>data</option> option may be used to configure arbitrary textual or binary data to pass via | |
2345 | standard input to the executed process. The data to pass is configured via | |
2346 | <varname>StandardInputText=</varname>/<varname>StandardInputData=</varname> (see below). Note that the actual | |
2347 | file descriptor type passed (memory file, regular file, UNIX pipe, …) might depend on the kernel and available | |
2348 | privileges. In any case, the file descriptor is read-only, and when read returns the specified data followed by | |
2349 | EOF.</para> | |
2350 | ||
2351 | <para>The <option>file:<replaceable>path</replaceable></option> option may be used to connect a specific file | |
2352 | system object to standard input. An absolute path following the <literal>:</literal> character is expected, | |
2353 | which may refer to a regular file, a FIFO or special file. If an <constant>AF_UNIX</constant> socket in the | |
2354 | file system is specified, a stream socket is connected to it. The latter is useful for connecting standard | |
2355 | input of processes to arbitrary system services.</para> | |
2356 | ||
2357 | <para>The <option>socket</option> option is valid in socket-activated services only, and requires the relevant | |
2358 | socket unit file (see | |
2359 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details) | |
2360 | to have <varname>Accept=yes</varname> set, or to specify a single socket only. If this option is set, standard | |
2361 | input will be connected to the socket the service was activated from, which is primarily useful for | |
2362 | compatibility with daemons designed for use with the traditional <citerefentry | |
2363 | project='freebsd'><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry> socket activation | |
2364 | daemon.</para> | |
2365 | ||
2366 | <para>The <option>fd:<replaceable>name</replaceable></option> option connects standard input to a specific, | |
2367 | named file descriptor provided by a socket unit. The name may be specified as part of this option, following a | |
2368 | <literal>:</literal> character (e.g. <literal>fd:foobar</literal>). If no name is specified, the name | |
2369 | <literal>stdin</literal> is implied (i.e. <literal>fd</literal> is equivalent to <literal>fd:stdin</literal>). | |
2370 | At least one socket unit defining the specified name must be provided via the <varname>Sockets=</varname> | |
2371 | option, and the file descriptor name may differ from the name of its containing socket unit. If multiple | |
2372 | matches are found, the first one will be used. See <varname>FileDescriptorName=</varname> in | |
2373 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more | |
2374 | details about named file descriptors and their ordering.</para> | |
2375 | ||
8fa2cd83 | 2376 | <para>This setting defaults to <option>null</option>.</para></listitem> |
b8afec21 LP |
2377 | </varlistentry> |
2378 | ||
2379 | <varlistentry> | |
2380 | <term><varname>StandardOutput=</varname></term> | |
2381 | ||
d58b613b | 2382 | <listitem><para>Controls where file descriptor 1 (stdout) of the executed processes is connected |
eedaf7f3 LP |
2383 | to. Takes one of <option>inherit</option>, <option>null</option>, <option>tty</option>, |
2384 | <option>journal</option>, <option>kmsg</option>, <option>journal+console</option>, | |
2385 | <option>kmsg+console</option>, <option>file:<replaceable>path</replaceable></option>, | |
2386 | <option>append:<replaceable>path</replaceable></option>, <option>socket</option> or | |
2387 | <option>fd:<replaceable>name</replaceable></option>.</para> | |
b8afec21 LP |
2388 | |
2389 | <para><option>inherit</option> duplicates the file descriptor of standard input for standard output.</para> | |
2390 | ||
2391 | <para><option>null</option> connects standard output to <filename>/dev/null</filename>, i.e. everything written | |
2392 | to it will be lost.</para> | |
2393 | ||
2394 | <para><option>tty</option> connects standard output to a tty (as configured via <varname>TTYPath=</varname>, | |
2395 | see below). If the TTY is used for output only, the executed process will not become the controlling process of | |
2396 | the terminal, and will not fail or wait for other processes to release the terminal.</para> | |
2397 | ||
eedaf7f3 LP |
2398 | <para><option>journal</option> connects standard output with the journal, which is accessible via |
2399 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Note | |
2400 | that everything that is written to kmsg (see below) is implicitly stored in the journal as well, the | |
2401 | specific option listed below is hence a superset of this one. (Also note that any external, | |
2402 | additional syslog daemons receive their log data from the journal, too, hence this is the option to | |
2403 | use when logging shall be processed with such a daemon.)</para> | |
b8afec21 LP |
2404 | |
2405 | <para><option>kmsg</option> connects standard output with the kernel log buffer which is accessible via | |
2406 | <citerefentry project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
2407 | in addition to the journal. The journal daemon might be configured to send all logs to kmsg anyway, in which | |
2408 | case this option is no different from <option>journal</option>.</para> | |
2409 | ||
eedaf7f3 LP |
2410 | <para><option>journal+console</option> and <option>kmsg+console</option> work in a similar way as the |
2411 | two options above but copy the output to the system console as well.</para> | |
b8afec21 LP |
2412 | |
2413 | <para>The <option>file:<replaceable>path</replaceable></option> option may be used to connect a specific file | |
2414 | system object to standard output. The semantics are similar to the same option of | |
566b7d23 ZD |
2415 | <varname>StandardInput=</varname>, see above. If <replaceable>path</replaceable> refers to a regular file |
2416 | on the filesystem, it is opened (created if it doesn't exist yet) for writing at the beginning of the file, | |
2417 | but without truncating it. | |
2418 | If standard input and output are directed to the same file path, it is opened only once, for reading as well | |
2419 | as writing and duplicated. This is particularly useful when the specified path refers to an | |
2420 | <constant>AF_UNIX</constant> socket in the file system, as in that case only a | |
b8afec21 LP |
2421 | single stream connection is created for both input and output.</para> |
2422 | ||
e9dd6984 ZJS |
2423 | <para><option>append:<replaceable>path</replaceable></option> is similar to |
2424 | <option>file:<replaceable>path</replaceable></option> above, but it opens the file in append mode. | |
2425 | </para> | |
566b7d23 | 2426 | |
b8afec21 LP |
2427 | <para><option>socket</option> connects standard output to a socket acquired via socket activation. The |
2428 | semantics are similar to the same option of <varname>StandardInput=</varname>, see above.</para> | |
2429 | ||
2430 | <para>The <option>fd:<replaceable>name</replaceable></option> option connects standard output to a specific, | |
2431 | named file descriptor provided by a socket unit. A name may be specified as part of this option, following a | |
2432 | <literal>:</literal> character (e.g. <literal>fd:foobar</literal>). If no name is specified, the name | |
2433 | <literal>stdout</literal> is implied (i.e. <literal>fd</literal> is equivalent to | |
2434 | <literal>fd:stdout</literal>). At least one socket unit defining the specified name must be provided via the | |
2435 | <varname>Sockets=</varname> option, and the file descriptor name may differ from the name of its containing | |
2436 | socket unit. If multiple matches are found, the first one will be used. See | |
2437 | <varname>FileDescriptorName=</varname> in | |
2438 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more | |
2439 | details about named descriptors and their ordering.</para> | |
2440 | ||
eedaf7f3 LP |
2441 | <para>If the standard output (or error output, see below) of a unit is connected to the journal or |
2442 | the kernel log buffer, the unit will implicitly gain a dependency of type <varname>After=</varname> | |
2443 | on <filename>systemd-journald.socket</filename> (also see the "Implicit Dependencies" section | |
2444 | above). Also note that in this case stdout (or stderr, see below) will be an | |
2445 | <constant>AF_UNIX</constant> stream socket, and not a pipe or FIFO that can be re-opened. This means | |
2446 | when executing shell scripts the construct <command>echo "hello" > /dev/stderr</command> for | |
2447 | writing text to stderr will not work. To mitigate this use the construct <command>echo "hello" | |
2448 | >&2</command> instead, which is mostly equivalent and avoids this pitfall.</para> | |
b8afec21 LP |
2449 | |
2450 | <para>This setting defaults to the value set with <varname>DefaultStandardOutput=</varname> in | |
2451 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, which | |
2452 | defaults to <option>journal</option>. Note that setting this parameter might result in additional dependencies | |
2453 | to be added to the unit (see above).</para></listitem> | |
2454 | </varlistentry> | |
2455 | ||
2456 | <varlistentry> | |
2457 | <term><varname>StandardError=</varname></term> | |
2458 | ||
d58b613b | 2459 | <listitem><para>Controls where file descriptor 2 (stderr) of the executed processes is connected to. The |
b8afec21 LP |
2460 | available options are identical to those of <varname>StandardOutput=</varname>, with some exceptions: if set to |
2461 | <option>inherit</option> the file descriptor used for standard output is duplicated for standard error, while | |
2462 | <option>fd:<replaceable>name</replaceable></option> will use a default file descriptor name of | |
2463 | <literal>stderr</literal>.</para> | |
2464 | ||
2465 | <para>This setting defaults to the value set with <varname>DefaultStandardError=</varname> in | |
2466 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, which | |
2467 | defaults to <option>inherit</option>. Note that setting this parameter might result in additional dependencies | |
2468 | to be added to the unit (see above).</para></listitem> | |
2469 | </varlistentry> | |
2470 | ||
2471 | <varlistentry> | |
2472 | <term><varname>StandardInputText=</varname></term> | |
2473 | <term><varname>StandardInputData=</varname></term> | |
2474 | ||
2475 | <listitem><para>Configures arbitrary textual or binary data to pass via file descriptor 0 (STDIN) to the | |
2476 | executed processes. These settings have no effect unless <varname>StandardInput=</varname> is set to | |
2477 | <option>data</option>. Use this option to embed process input data directly in the unit file.</para> | |
2478 | ||
2479 | <para><varname>StandardInputText=</varname> accepts arbitrary textual data. C-style escapes for special | |
2480 | characters as well as the usual <literal>%</literal>-specifiers are resolved. Each time this setting is used | |
1b2ad5d9 | 2481 | the specified text is appended to the per-unit data buffer, followed by a newline character (thus every use |
b8afec21 LP |
2482 | appends a new line to the end of the buffer). Note that leading and trailing whitespace of lines configured |
2483 | with this option is removed. If an empty line is specified the buffer is cleared (hence, in order to insert an | |
2484 | empty line, add an additional <literal>\n</literal> to the end or beginning of a line).</para> | |
2485 | ||
2486 | <para><varname>StandardInputData=</varname> accepts arbitrary binary data, encoded in <ulink | |
2487 | url="https://tools.ietf.org/html/rfc2045#section-6.8">Base64</ulink>. No escape sequences or specifiers are | |
2488 | resolved. Any whitespace in the encoded version is ignored during decoding.</para> | |
2489 | ||
2490 | <para>Note that <varname>StandardInputText=</varname> and <varname>StandardInputData=</varname> operate on the | |
2491 | same data buffer, and may be mixed in order to configure both binary and textual data for the same input | |
2492 | stream. The textual or binary data is joined strictly in the order the settings appear in the unit | |
2493 | file. Assigning an empty string to either will reset the data buffer.</para> | |
2494 | ||
2495 | <para>Please keep in mind that in order to maintain readability long unit file settings may be split into | |
2496 | multiple lines, by suffixing each line (except for the last) with a <literal>\</literal> character (see | |
2497 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for | |
2498 | details). This is particularly useful for large data configured with these two options. Example:</para> | |
2499 | ||
2500 | <programlisting>… | |
2501 | StandardInput=data | |
2502 | StandardInputData=SWNrIHNpdHplIGRhIHVuJyBlc3NlIEtsb3BzLAp1ZmYgZWVtYWwga2xvcHAncy4KSWNrIGtpZWtl \ | |
2503 | LCBzdGF1bmUsIHd1bmRyZSBtaXIsCnVmZiBlZW1hbCBqZWh0IHNlIHVmZiBkaWUgVMO8ci4KTmFu \ | |
2504 | dSwgZGVuayBpY2ssIGljayBkZW5rIG5hbnUhCkpldHogaXNzZSB1ZmYsIGVyc2NodCB3YXIgc2Ug \ | |
2505 | enUhCkljayBqZWhlIHJhdXMgdW5kIGJsaWNrZSDigJQKdW5kIHdlciBzdGVodCBkcmF1w59lbj8g \ | |
2506 | SWNrZSEK | |
2507 | …</programlisting></listitem> | |
798d3a52 ZJS |
2508 | </varlistentry> |
2509 | ||
2510 | <varlistentry> | |
b8afec21 | 2511 | <term><varname>LogLevelMax=</varname></term> |
142bd808 | 2512 | |
b8afec21 LP |
2513 | <listitem><para>Configures filtering by log level of log messages generated by this unit. Takes a |
2514 | <command>syslog</command> log level, one of <option>emerg</option> (lowest log level, only highest priority | |
2515 | messages), <option>alert</option>, <option>crit</option>, <option>err</option>, <option>warning</option>, | |
2516 | <option>notice</option>, <option>info</option>, <option>debug</option> (highest log level, also lowest priority | |
2517 | messages). See <citerefentry | |
2518 | project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
2519 | details. By default no filtering is applied (i.e. the default maximum log level is <option>debug</option>). Use | |
2520 | this option to configure the logging system to drop log messages of a specific service above the specified | |
2521 | level. For example, set <varname>LogLevelMax=</varname><option>info</option> in order to turn off debug logging | |
1b2ad5d9 | 2522 | of a particularly chatty unit. Note that the configured level is applied to any log messages written by any |
b8afec21 LP |
2523 | of the processes belonging to this unit, sent via any supported logging protocol. The filtering is applied |
2524 | early in the logging pipeline, before any kind of further processing is done. Moreover, messages which pass | |
2525 | through this filter successfully might still be dropped by filters applied at a later stage in the logging | |
2526 | subsystem. For example, <varname>MaxLevelStore=</varname> configured in | |
2527 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> might | |
2528 | prohibit messages of higher log levels to be stored on disk, even though the per-unit | |
2529 | <varname>LogLevelMax=</varname> permitted it to be processed.</para></listitem> | |
798d3a52 ZJS |
2530 | </varlistentry> |
2531 | ||
add00535 | 2532 | <varlistentry> |
b8afec21 | 2533 | <term><varname>LogExtraFields=</varname></term> |
add00535 | 2534 | |
db11487d ZJS |
2535 | <listitem><para>Configures additional log metadata fields to include in all log records generated by |
2536 | processes associated with this unit. This setting takes one or more journal field assignments in the | |
2537 | format <literal>FIELD=VALUE</literal> separated by whitespace. See | |
2538 | <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
2539 | for details on the journal field concept. Even though the underlying journal implementation permits | |
2540 | binary field values, this setting accepts only valid UTF-8 values. To include space characters in a | |
2541 | journal field value, enclose the assignment in double quotes ("). <!-- " fake closing quote for emacs--> | |
2542 | The usual specifiers are expanded in all assignments (see below). Note that this setting is not only | |
2543 | useful for attaching additional metadata to log records of a unit, but given that all fields and | |
2544 | values are indexed may also be used to implement cross-unit log record matching. Assign an empty | |
2545 | string to reset the list.</para></listitem> | |
add00535 LP |
2546 | </varlistentry> |
2547 | ||
90fc172e AZ |
2548 | <varlistentry> |
2549 | <term><varname>LogRateLimitIntervalSec=</varname></term> | |
2550 | <term><varname>LogRateLimitBurst=</varname></term> | |
2551 | ||
2552 | <listitem><para>Configures the rate limiting that is applied to messages generated by this unit. If, in the | |
2553 | time interval defined by <varname>LogRateLimitIntervalSec=</varname>, more messages than specified in | |
2554 | <varname>LogRateLimitBurst=</varname> are logged by a service, all further messages within the interval are | |
2555 | dropped until the interval is over. A message about the number of dropped messages is generated. The time | |
2556 | specification for <varname>LogRateLimitIntervalSec=</varname> may be specified in the following units: "s", | |
2557 | "min", "h", "ms", "us" (see | |
2558 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details). | |
2559 | The default settings are set by <varname>RateLimitIntervalSec=</varname> and <varname>RateLimitBurst=</varname> | |
2560 | configured in <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
2561 | </para></listitem> | |
2562 | </varlistentry> | |
2563 | ||
5b0a76d1 LP |
2564 | <varlistentry> |
2565 | <term><varname>LogNamespace=</varname></term> | |
2566 | ||
2567 | <listitem><para>Run the unit's processes in the specified journal namespace. Expects a short | |
2568 | user-defined string identifying the namespace. If not used the processes of the service are run in | |
2569 | the default journal namespace, i.e. their log stream is collected and processed by | |
2570 | <filename>systemd-journald.service</filename>. If this option is used any log data generated by | |
2571 | processes of this unit (regardless if via the <function>syslog()</function>, journal native logging | |
2572 | or stdout/stderr logging) is collected and processed by an instance of the | |
2573 | <filename>systemd-journald@.service</filename> template unit, which manages the specified | |
2574 | namespace. The log data is stored in a data store independent from the default log namespace's data | |
2575 | store. See | |
2576 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
2577 | for details about journal namespaces.</para> | |
2578 | ||
2579 | <para>Internally, journal namespaces are implemented through Linux mount namespacing and | |
2580 | over-mounting the directory that contains the relevant <constant>AF_UNIX</constant> sockets used for | |
2581 | logging in the unit's mount namespace. Since mount namespaces are used this setting disconnects | |
2582 | propagation of mounts from the unit's processes to the host, similar to how | |
2583 | <varname>ReadOnlyPaths=</varname> and similar settings (see above) work. Journal namespaces may hence | |
2584 | not be used for services that need to establish mount points on the host.</para> | |
2585 | ||
2586 | <para>When this option is used the unit will automatically gain ordering and requirement dependencies | |
2587 | on the two socket units associated with the <filename>systemd-journald@.service</filename> instance | |
2588 | so that they are automatically established prior to the unit starting up. Note that when this option | |
2589 | is used log output of this service does not appear in the regular | |
2590 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
a6991726 LP |
2591 | output, unless the <option>--namespace=</option> option is used.</para> |
2592 | ||
2593 | <xi:include href="system-only.xml" xpointer="singular"/></listitem> | |
5b0a76d1 LP |
2594 | </varlistentry> |
2595 | ||
798d3a52 | 2596 | <varlistentry> |
b8afec21 | 2597 | <term><varname>SyslogIdentifier=</varname></term> |
798d3a52 | 2598 | |
eedaf7f3 LP |
2599 | <listitem><para>Sets the process name ("<command>syslog</command> tag") to prefix log lines sent to |
2600 | the logging system or the kernel log buffer with. If not set, defaults to the process name of the | |
2601 | executed process. This option is only useful when <varname>StandardOutput=</varname> or | |
2602 | <varname>StandardError=</varname> are set to <option>journal</option> or <option>kmsg</option> (or to | |
2603 | the same settings in combination with <option>+console</option>) and only applies to log messages | |
2604 | written to stdout or stderr.</para></listitem> | |
798d3a52 ZJS |
2605 | </varlistentry> |
2606 | ||
2607 | <varlistentry> | |
b8afec21 | 2608 | <term><varname>SyslogFacility=</varname></term> |
78e864e5 | 2609 | |
b8afec21 LP |
2610 | <listitem><para>Sets the <command>syslog</command> facility identifier to use when logging. One of |
2611 | <option>kern</option>, <option>user</option>, <option>mail</option>, <option>daemon</option>, | |
2612 | <option>auth</option>, <option>syslog</option>, <option>lpr</option>, <option>news</option>, | |
2613 | <option>uucp</option>, <option>cron</option>, <option>authpriv</option>, <option>ftp</option>, | |
2614 | <option>local0</option>, <option>local1</option>, <option>local2</option>, <option>local3</option>, | |
eedaf7f3 LP |
2615 | <option>local4</option>, <option>local5</option>, <option>local6</option> or |
2616 | <option>local7</option>. See <citerefentry | |
2617 | project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
2618 | details. This option is only useful when <varname>StandardOutput=</varname> or | |
2619 | <varname>StandardError=</varname> are set to <option>journal</option> or <option>kmsg</option> (or to | |
2620 | the same settings in combination with <option>+console</option>), and only applies to log messages | |
2621 | written to stdout or stderr. Defaults to <option>daemon</option>.</para></listitem> | |
78e864e5 TM |
2622 | </varlistentry> |
2623 | ||
b1edf445 | 2624 | <varlistentry> |
b8afec21 | 2625 | <term><varname>SyslogLevel=</varname></term> |
b1edf445 | 2626 | |
b8afec21 LP |
2627 | <listitem><para>The default <command>syslog</command> log level to use when logging to the logging system or |
2628 | the kernel log buffer. One of <option>emerg</option>, <option>alert</option>, <option>crit</option>, | |
2629 | <option>err</option>, <option>warning</option>, <option>notice</option>, <option>info</option>, | |
2630 | <option>debug</option>. See <citerefentry | |
2631 | project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for | |
2632 | details. This option is only useful when <varname>StandardOutput=</varname> or | |
eedaf7f3 | 2633 | <varname>StandardError=</varname> are set to <option>journal</option> or |
b8afec21 LP |
2634 | <option>kmsg</option> (or to the same settings in combination with <option>+console</option>), and only applies |
2635 | to log messages written to stdout or stderr. Note that individual lines output by executed processes may be | |
2636 | prefixed with a different log level which can be used to override the default log level specified here. The | |
2637 | interpretation of these prefixes may be disabled with <varname>SyslogLevelPrefix=</varname>, see below. For | |
2638 | details, see <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
2639 | Defaults to <option>info</option>.</para></listitem> | |
78e864e5 TM |
2640 | </varlistentry> |
2641 | ||
2642 | <varlistentry> | |
b8afec21 | 2643 | <term><varname>SyslogLevelPrefix=</varname></term> |
4a628360 | 2644 | |
b8afec21 | 2645 | <listitem><para>Takes a boolean argument. If true and <varname>StandardOutput=</varname> or |
eedaf7f3 LP |
2646 | <varname>StandardError=</varname> are set to <option>journal</option> or <option>kmsg</option> (or to |
2647 | the same settings in combination with <option>+console</option>), log lines written by the executed | |
2648 | process that are prefixed with a log level will be processed with this log level set but the prefix | |
2649 | removed. If set to false, the interpretation of these prefixes is disabled and the logged lines are | |
2650 | passed on as-is. This only applies to log messages written to stdout or stderr. For details about | |
2651 | this prefixing see | |
2652 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
b8afec21 LP |
2653 | Defaults to true.</para></listitem> |
2654 | </varlistentry> | |
fdfcb946 | 2655 | |
b8afec21 LP |
2656 | <varlistentry> |
2657 | <term><varname>TTYPath=</varname></term> | |
4a628360 | 2658 | |
b8afec21 LP |
2659 | <listitem><para>Sets the terminal device node to use if standard input, output, or error are connected to a TTY |
2660 | (see above). Defaults to <filename>/dev/console</filename>.</para></listitem> | |
2661 | </varlistentry> | |
23a7448e | 2662 | |
b8afec21 LP |
2663 | <varlistentry> |
2664 | <term><varname>TTYReset=</varname></term> | |
3536f49e | 2665 | |
b8afec21 LP |
2666 | <listitem><para>Reset the terminal device specified with <varname>TTYPath=</varname> before and after |
2667 | execution. Defaults to <literal>no</literal>.</para></listitem> | |
3536f49e YW |
2668 | </varlistentry> |
2669 | ||
189cd8c2 | 2670 | <varlistentry> |
b8afec21 | 2671 | <term><varname>TTYVHangup=</varname></term> |
189cd8c2 | 2672 | |
b8afec21 LP |
2673 | <listitem><para>Disconnect all clients which have opened the terminal device specified with |
2674 | <varname>TTYPath=</varname> before and after execution. Defaults to <literal>no</literal>.</para></listitem> | |
189cd8c2 ZJS |
2675 | </varlistentry> |
2676 | ||
53f47dfc | 2677 | <varlistentry> |
b8afec21 | 2678 | <term><varname>TTYVTDisallocate=</varname></term> |
53f47dfc | 2679 | |
b8afec21 LP |
2680 | <listitem><para>If the terminal device specified with <varname>TTYPath=</varname> is a virtual console |
2681 | terminal, try to deallocate the TTY before and after execution. This ensures that the screen and scrollback | |
2682 | buffer is cleared. Defaults to <literal>no</literal>.</para></listitem> | |
189cd8c2 | 2683 | </varlistentry> |
b8afec21 LP |
2684 | </variablelist> |
2685 | </refsect1> | |
2686 | ||
3220cf39 LP |
2687 | <refsect1> |
2688 | <title>Credentials</title> | |
2689 | ||
2690 | <variablelist class='unit-directives'> | |
2691 | ||
2692 | <varlistentry> | |
2693 | <term><varname>LoadCredential=</varname><replaceable>ID</replaceable>:<replaceable>PATH</replaceable></term> | |
2694 | ||
2695 | <listitem><para>Pass a credential to the unit. Credentials are limited-size binary or textual objects | |
2696 | that may be passed to unit processes. They are primarily used for passing cryptographic keys (both | |
2697 | public and private) or certificates, user account information or identity information from host to | |
2698 | services. The data is accessible from the unit's processes via the file system, at a read-only | |
2699 | location that (if possible and permitted) is backed by non-swappable memory. The data is only | |
2700 | accessible to the user associated with the unit, via the | |
2701 | <varname>User=</varname>/<varname>DynamicUser=</varname> settings (as well as the superuser). When | |
2702 | available, the location of credentials is exported as the <varname>$CREDENTIALS_DIRECTORY</varname> | |
2703 | environment variable to the unit's processes.</para> | |
2704 | ||
2705 | <para>The <varname>LoadCredential=</varname> setting takes a textual ID to use as name for a | |
2706 | credential plus a file system path. The ID must be a short ASCII string suitable as filename in the | |
2707 | filesystem, and may be chosen freely by the user. If the specified path is absolute it is opened as | |
2708 | regular file and the credential data is read from it. If the absolute path refers to an | |
d3dcf4e3 LP |
2709 | <constant>AF_UNIX</constant> stream socket in the file system a connection is made to it (only once |
2710 | at unit start-up) and the credential data read from the connection, providing an easy IPC integration | |
2711 | point for dynamically providing credentials from other services. If the specified path is not | |
2712 | absolute and itself qualifies as valid credential identifier it is understood to refer to a | |
2713 | credential that the service manager itself received via the <varname>$CREDENTIALS_DIRECTORY</varname> | |
2714 | environment variable, which may be used to propagate credentials from an invoking environment (e.g. a | |
2715 | container manager that invoked the service manager) into a service. The contents of the file/socket | |
2716 | may be arbitrary binary or textual data, including newline characters and <constant>NUL</constant> | |
2717 | bytes. This option may be used multiple times, each time defining an additional credential to pass to | |
2718 | the unit.</para> | |
3220cf39 LP |
2719 | |
2720 | <para>The credential files/IPC sockets must be accessible to the service manager, but don't have to | |
2721 | be directly accessible to the unit's processes: the credential data is read and copied into separate, | |
2722 | read-only copies for the unit that are accessible to appropriately privileged processes. This is | |
2723 | particularly useful in combination with <varname>DynamicUser=</varname> as this way privileged data | |
2724 | can be made available to processes running under a dynamic UID (i.e. not a previously known one) | |
2725 | without having to open up access to all users.</para> | |
2726 | ||
2727 | <para>In order to reference the path a credential may be read from within a | |
2728 | <varname>ExecStart=</varname> command line use <literal>${CREDENTIALS_DIRECTORY}/mycred</literal>, | |
2729 | e.g. <literal>ExecStart=cat ${CREDENTIALS_DIRECTORY}/mycred</literal>.</para> | |
2730 | ||
2731 | <para>Currently, an accumulated credential size limit of 1M bytes per unit is | |
d3dcf4e3 LP |
2732 | enforced.</para> |
2733 | ||
2734 | <para>If referencing an <constant>AF_UNIX</constant> stream socket to connect to, the connection will | |
2735 | originate from an abstract namespace socket, that includes information about the unit and the | |
2736 | credential ID in its socket name. Use <citerefentry | |
2737 | project='man-pages'><refentrytitle>getpeername</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
2738 | to query this information. The returned socket name is formatted as <constant>NUL</constant> | |
2739 | <replaceable>RANDOM</replaceable> <literal>/unit/</literal> <replaceable>UNIT</replaceable> | |
2740 | <literal>/</literal> <replaceable>ID</replaceable>, i.e. a <constant>NUL</constant> byte (as required | |
2741 | for abstract namespace socket names), followed by a random string (consisting of alphadecimal | |
2742 | characters), followed by the literal string <literal>/unit/</literal>, followed by the requesting | |
2743 | unit name, followed by the literal character <literal>/</literal>, followed by the textual credential | |
2744 | ID requested. Example: <literal>\0adf9d86b6eda275e/unit/foobar.service/credx</literal> in case the | |
2745 | credential <literal>credx</literal> is requested for a unit <literal>foobar.service</literal>. This | |
2746 | functionality is useful for using a single listening socket to serve credentials to multiple | |
2747 | consumers.</para></listitem> | |
3220cf39 LP |
2748 | </varlistentry> |
2749 | ||
2750 | <varlistentry> | |
2751 | <term><varname>SetCredential=</varname><replaceable>ID</replaceable>:<replaceable>VALUE</replaceable></term> | |
2752 | ||
2753 | <listitem><para>The <varname>SetCredential=</varname> setting is similar to | |
2754 | <varname>LoadCredential=</varname> but accepts a literal value to use as data for the credential, | |
2755 | instead of a file system path to read the data from. Do not use this option for data that is supposed | |
2756 | to be secret, as it is accessible to unprivileged processes via IPC. It's only safe to use this for | |
2757 | user IDs, public key material and similar non-sensitive data. For everything else use | |
2758 | <varname>LoadCredential=</varname>. In order to embed binary data into the credential data use | |
2759 | C-style escaping (i.e. <literal>\n</literal> to embed a newline, or <literal>\x00</literal> to embed | |
6b44ad0b | 2760 | a <constant>NUL</constant> byte).</para> |
3220cf39 LP |
2761 | |
2762 | <para>If a credential of the same ID is listed in both <varname>LoadCredential=</varname> and | |
2763 | <varname>SetCredential=</varname>, the latter will act as default if the former cannot be | |
2764 | retrieved. In this case not being able to retrieve the credential from the path specified in | |
2765 | <varname>LoadCredential=</varname> is not considered fatal.</para></listitem> | |
2766 | </varlistentry> | |
2767 | </variablelist> | |
2768 | </refsect1> | |
2769 | ||
b8afec21 LP |
2770 | <refsect1> |
2771 | <title>System V Compatibility</title> | |
e0e2ecd5 | 2772 | <variablelist class='unit-directives'> |
189cd8c2 | 2773 | |
f3e43635 | 2774 | <varlistentry> |
b8afec21 | 2775 | <term><varname>UtmpIdentifier=</varname></term> |
f3e43635 | 2776 | |
b8afec21 LP |
2777 | <listitem><para>Takes a four character identifier string for an <citerefentry |
2778 | project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry> and wtmp entry | |
2779 | for this service. This should only be set for services such as <command>getty</command> implementations (such | |
2780 | as <citerefentry | |
2781 | project='die-net'><refentrytitle>agetty</refentrytitle><manvolnum>8</manvolnum></citerefentry>) where utmp/wtmp | |
2782 | entries must be created and cleared before and after execution, or for services that shall be executed as if | |
2783 | they were run by a <command>getty</command> process (see below). If the configured string is longer than four | |
2784 | characters, it is truncated and the terminal four characters are used. This setting interprets %I style string | |
2785 | replacements. This setting is unset by default, i.e. no utmp/wtmp entries are created or cleaned up for this | |
2786 | service.</para></listitem> | |
f3e43635 TM |
2787 | </varlistentry> |
2788 | ||
f4170c67 | 2789 | <varlistentry> |
b8afec21 | 2790 | <term><varname>UtmpMode=</varname></term> |
f4170c67 | 2791 | |
b8afec21 LP |
2792 | <listitem><para>Takes one of <literal>init</literal>, <literal>login</literal> or <literal>user</literal>. If |
2793 | <varname>UtmpIdentifier=</varname> is set, controls which type of <citerefentry | |
2794 | project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry>/wtmp entries | |
2795 | for this service are generated. This setting has no effect unless <varname>UtmpIdentifier=</varname> is set | |
2796 | too. If <literal>init</literal> is set, only an <constant>INIT_PROCESS</constant> entry is generated and the | |
2797 | invoked process must implement a <command>getty</command>-compatible utmp/wtmp logic. If | |
2798 | <literal>login</literal> is set, first an <constant>INIT_PROCESS</constant> entry, followed by a | |
2799 | <constant>LOGIN_PROCESS</constant> entry is generated. In this case, the invoked process must implement a | |
2800 | <citerefentry | |
2801 | project='die-net'><refentrytitle>login</refentrytitle><manvolnum>1</manvolnum></citerefentry>-compatible | |
2802 | utmp/wtmp logic. If <literal>user</literal> is set, first an <constant>INIT_PROCESS</constant> entry, then a | |
2803 | <constant>LOGIN_PROCESS</constant> entry and finally a <constant>USER_PROCESS</constant> entry is | |
2804 | generated. In this case, the invoked process may be any process that is suitable to be run as session | |
2805 | leader. Defaults to <literal>init</literal>.</para></listitem> | |
f4170c67 LP |
2806 | </varlistentry> |
2807 | ||
798d3a52 ZJS |
2808 | </variablelist> |
2809 | </refsect1> | |
2810 | ||
2811 | <refsect1> | |
82651d5b | 2812 | <title>Environment Variables in Spawned Processes</title> |
798d3a52 | 2813 | |
00819cc1 LP |
2814 | <para>Processes started by the service manager are executed with an environment variable block assembled from |
2815 | multiple sources. Processes started by the system service manager generally do not inherit environment variables | |
2816 | set for the service manager itself (but this may be altered via <varname>PassEnvironment=</varname>), but processes | |
2817 | started by the user service manager instances generally do inherit all environment variables set for the service | |
2818 | manager itself.</para> | |
2819 | ||
2820 | <para>For each invoked process the list of environment variables set is compiled from the following sources:</para> | |
2821 | ||
2822 | <itemizedlist> | |
2823 | <listitem><para>Variables globally configured for the service manager, using the | |
2824 | <varname>DefaultEnvironment=</varname> setting in | |
82651d5b ZJS |
2825 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
2826 | the kernel command line option <varname>systemd.setenv=</varname> understood by | |
2827 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, or via | |
2828 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
2829 | <command>set-environment</command> verb.</para></listitem> | |
00819cc1 | 2830 | |
82651d5b | 2831 | <listitem><para>Variables defined by the service manager itself (see the list below).</para></listitem> |
00819cc1 | 2832 | |
82651d5b ZJS |
2833 | <listitem><para>Variables set in the service manager's own environment variable block (subject to |
2834 | <varname>PassEnvironment=</varname> for the system service manager).</para></listitem> | |
00819cc1 | 2835 | |
82651d5b | 2836 | <listitem><para>Variables set via <varname>Environment=</varname> in the unit file.</para></listitem> |
00819cc1 | 2837 | |
82651d5b ZJS |
2838 | <listitem><para>Variables read from files specified via <varname>EnvironmentFile=</varname> in the unit |
2839 | file.</para></listitem> | |
00819cc1 | 2840 | |
46b07329 LP |
2841 | <listitem><para>Variables set by any PAM modules in case <varname>PAMName=</varname> is in effect, |
2842 | cf. <citerefentry | |
82651d5b ZJS |
2843 | project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>. |
2844 | </para></listitem> | |
00819cc1 LP |
2845 | </itemizedlist> |
2846 | ||
82651d5b ZJS |
2847 | <para>If the same environment variable is set by multiple of these sources, the later source — according |
2848 | to the order of the list above — wins. Note that as the final step all variables listed in | |
2849 | <varname>UnsetEnvironment=</varname> are removed from the compiled environment variable list, immediately | |
00819cc1 LP |
2850 | before it is passed to the executed process.</para> |
2851 | ||
82651d5b ZJS |
2852 | <para>The general philosophy is to expose a small curated list of environment variables to processes. |
2853 | Services started by the system manager (PID 1) will be started, without additional service-specific | |
2854 | configuration, with just a few environment variables. The user manager inherits environment variables as | |
2855 | any other system service, but in addition may receive additional environment variables from PAM, and, | |
2856 | typically, additional imported variables when the user starts a graphical session. It is recommended to | |
32854f70 ZJS |
2857 | keep the environment blocks in both the system and user managers managers lean. Importing all variables |
2858 | inherited by the graphical session or by one of the user shells is strongly discouraged.</para> | |
82651d5b ZJS |
2859 | |
2860 | <para>Hint: <command>systemd-run -P env</command> and <command>systemd-run --user -P env</command> print | |
2861 | the effective system and user service environment blocks.</para> | |
2862 | ||
2863 | <refsect2> | |
2864 | <title>Environment Variables Set or Propagated by the Service Manager</title> | |
2865 | ||
2866 | <para>The following environment variables are propagated by the service manager or generated internally | |
2867 | for each invoked process:</para> | |
2868 | ||
2869 | <variablelist class='environment-variables'> | |
2870 | <varlistentry> | |
2871 | <term><varname>$PATH</varname></term> | |
2872 | ||
2873 | <listitem><para>Colon-separated list of directories to use when launching | |
2874 | executables. <command>systemd</command> uses a fixed value of | |
2875 | <literal><filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename></literal> | |
2876 | in the system manager. When compiled for systems with "unmerged <filename>/usr/</filename>" | |
2877 | (<filename>/bin</filename> is not a symlink to <filename>/usr/bin</filename>), | |
2878 | <literal>:<filename>/sbin</filename>:<filename>/bin</filename></literal> is appended. In case of | |
2879 | the the user manager, a different path may be configured by the distribution. It is recommended to | |
2880 | not rely on the order of entries, and have only one program with a given name in | |
2881 | <varname>$PATH</varname>.</para></listitem> | |
2882 | </varlistentry> | |
2883 | ||
2884 | <varlistentry> | |
2885 | <term><varname>$LANG</varname></term> | |
2886 | ||
2887 | <listitem><para>Locale. Can be set in <citerefentry | |
2888 | project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
2889 | or on the kernel command line (see | |
2890 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> and | |
2891 | <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>). | |
2892 | </para></listitem> | |
2893 | </varlistentry> | |
2894 | ||
2895 | <varlistentry> | |
2896 | <term><varname>$USER</varname></term> | |
2897 | <term><varname>$LOGNAME</varname></term> | |
2898 | <term><varname>$HOME</varname></term> | |
2899 | <term><varname>$SHELL</varname></term> | |
2900 | ||
2901 | <listitem><para>User name (twice), home directory, and the | |
2902 | login shell. The variables are set for the units that have | |
2903 | <varname>User=</varname> set, which includes user | |
2904 | <command>systemd</command> instances. See | |
2905 | <citerefentry project='die-net'><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
2906 | </para></listitem> | |
2907 | </varlistentry> | |
2908 | ||
2909 | <varlistentry> | |
2910 | <term><varname>$INVOCATION_ID</varname></term> | |
2911 | ||
2912 | <listitem><para>Contains a randomized, unique 128bit ID identifying each runtime cycle of the unit, formatted | |
2913 | as 32 character hexadecimal string. A new ID is assigned each time the unit changes from an inactive state into | |
2914 | an activating or active state, and may be used to identify this specific runtime cycle, in particular in data | |
2915 | stored offline, such as the journal. The same ID is passed to all processes run as part of the | |
2916 | unit.</para></listitem> | |
2917 | </varlistentry> | |
2918 | ||
2919 | <varlistentry> | |
2920 | <term><varname>$XDG_RUNTIME_DIR</varname></term> | |
2921 | ||
2922 | <listitem><para>The directory to use for runtime objects (such as IPC objects) and volatile state. Set for all | |
2923 | services run by the user <command>systemd</command> instance, as well as any system services that use | |
2924 | <varname>PAMName=</varname> with a PAM stack that includes <command>pam_systemd</command>. See below and | |
2925 | <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> for more | |
2926 | information.</para></listitem> | |
2927 | </varlistentry> | |
2928 | ||
2929 | <varlistentry> | |
2930 | <term><varname>$RUNTIME_DIRECTORY</varname></term> | |
2931 | <term><varname>$STATE_DIRECTORY</varname></term> | |
2932 | <term><varname>$CACHE_DIRECTORY</varname></term> | |
2933 | <term><varname>$LOGS_DIRECTORY</varname></term> | |
2934 | <term><varname>$CONFIGURATION_DIRECTORY</varname></term> | |
2935 | ||
2936 | <listitem><para>Absolute paths to the directories defined with | |
2937 | <varname>RuntimeDirectory=</varname>, <varname>StateDirectory=</varname>, | |
2938 | <varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname>, and | |
2939 | <varname>ConfigurationDirectory=</varname> when those settings are used.</para> | |
2940 | </listitem> | |
2941 | </varlistentry> | |
2942 | ||
2943 | <varlistentry> | |
2944 | <term><varname>$CREDENTIALS_DIRECTORY</varname></term> | |
2945 | ||
2946 | <listitem><para>An absolute path to the per-unit directory with credentials configured via | |
2947 | <varname>LoadCredential=</varname>/<varname>SetCredential=</varname>. The directory is marked | |
2948 | read-only and is placed in unswappable memory (if supported and permitted), and is only accessible to | |
2949 | the UID associated with the unit via <varname>User=</varname> or <varname>DynamicUser=</varname> (and | |
2950 | the superuser).</para></listitem> | |
2951 | </varlistentry> | |
2952 | ||
2953 | <varlistentry> | |
2954 | <term><varname>$MAINPID</varname></term> | |
2955 | ||
2956 | <listitem><para>The PID of the unit's main process if it is | |
2957 | known. This is only set for control processes as invoked by | |
2958 | <varname>ExecReload=</varname> and similar. </para></listitem> | |
2959 | </varlistentry> | |
2960 | ||
2961 | <varlistentry> | |
2962 | <term><varname>$MANAGERPID</varname></term> | |
2963 | ||
2964 | <listitem><para>The PID of the user <command>systemd</command> | |
2965 | instance, set for processes spawned by it. </para></listitem> | |
2966 | </varlistentry> | |
2967 | ||
2968 | <varlistentry> | |
2969 | <term><varname>$LISTEN_FDS</varname></term> | |
2970 | <term><varname>$LISTEN_PID</varname></term> | |
2971 | <term><varname>$LISTEN_FDNAMES</varname></term> | |
2972 | ||
2973 | <listitem><para>Information about file descriptors passed to a | |
2974 | service for socket activation. See | |
2975 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
2976 | </para></listitem> | |
2977 | </varlistentry> | |
2978 | ||
2979 | <varlistentry> | |
2980 | <term><varname>$NOTIFY_SOCKET</varname></term> | |
2981 | ||
2982 | <listitem><para>The socket | |
2983 | <function>sd_notify()</function> talks to. See | |
2984 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
2985 | </para></listitem> | |
2986 | </varlistentry> | |
2987 | ||
2988 | <varlistentry> | |
2989 | <term><varname>$WATCHDOG_PID</varname></term> | |
2990 | <term><varname>$WATCHDOG_USEC</varname></term> | |
2991 | ||
2992 | <listitem><para>Information about watchdog keep-alive notifications. See | |
2993 | <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
2994 | </para></listitem> | |
2995 | </varlistentry> | |
2996 | ||
2997 | <varlistentry> | |
2998 | <term><varname>$TERM</varname></term> | |
2999 | ||
3000 | <listitem><para>Terminal type, set only for units connected to | |
3001 | a terminal (<varname>StandardInput=tty</varname>, | |
3002 | <varname>StandardOutput=tty</varname>, or | |
3003 | <varname>StandardError=tty</varname>). See | |
3004 | <citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
3005 | </para></listitem> | |
3006 | </varlistentry> | |
3007 | ||
3008 | <varlistentry> | |
3009 | <term><varname>$LOG_NAMESPACE</varname></term> | |
3010 | ||
3011 | <listitem><para>Contains the name of the selected logging namespace when the | |
3012 | <varname>LogNamespace=</varname> service setting is used.</para></listitem> | |
3013 | </varlistentry> | |
3014 | ||
3015 | <varlistentry> | |
3016 | <term><varname>$JOURNAL_STREAM</varname></term> | |
3017 | ||
3018 | <listitem><para>If the standard output or standard error output of the executed processes are connected to the | |
3019 | journal (for example, by setting <varname>StandardError=journal</varname>) <varname>$JOURNAL_STREAM</varname> | |
3020 | contains the device and inode numbers of the connection file descriptor, formatted in decimal, separated by a | |
3021 | colon (<literal>:</literal>). This permits invoked processes to safely detect whether their standard output or | |
3022 | standard error output are connected to the journal. The device and inode numbers of the file descriptors should | |
3023 | be compared with the values set in the environment variable to determine whether the process output is still | |
3024 | connected to the journal. Note that it is generally not sufficient to only check whether | |
3025 | <varname>$JOURNAL_STREAM</varname> is set at all as services might invoke external processes replacing their | |
3026 | standard output or standard error output, without unsetting the environment variable.</para> | |
3027 | ||
3028 | <para>If both standard output and standard error of the executed processes are connected to the journal via a | |
3029 | stream socket, this environment variable will contain information about the standard error stream, as that's | |
3030 | usually the preferred destination for log data. (Note that typically the same stream is used for both standard | |
3031 | output and standard error, hence very likely the environment variable contains device and inode information | |
3032 | matching both stream file descriptors.)</para> | |
3033 | ||
3034 | <para>This environment variable is primarily useful to allow services to optionally upgrade their used log | |
3035 | protocol to the native journal protocol (using | |
3036 | <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry> and other | |
3037 | functions) if their standard output or standard error output is connected to the journal anyway, thus enabling | |
3038 | delivery of structured metadata along with logged messages.</para></listitem> | |
3039 | </varlistentry> | |
3040 | ||
3041 | <varlistentry> | |
3042 | <term><varname>$SERVICE_RESULT</varname></term> | |
3043 | ||
3044 | <listitem><para>Only defined for the service unit type, this environment variable is passed to all | |
3045 | <varname>ExecStop=</varname> and <varname>ExecStopPost=</varname> processes, and encodes the service | |
3046 | "result". Currently, the following values are defined:</para> | |
3047 | ||
3048 | <table> | |
3049 | <title>Defined <varname>$SERVICE_RESULT</varname> values</title> | |
3050 | <tgroup cols='2'> | |
3051 | <colspec colname='result'/> | |
3052 | <colspec colname='meaning'/> | |
3053 | <thead> | |
3054 | <row> | |
3055 | <entry>Value</entry> | |
3056 | <entry>Meaning</entry> | |
3057 | </row> | |
3058 | </thead> | |
3059 | ||
3060 | <tbody> | |
3061 | <row> | |
3062 | <entry><literal>success</literal></entry> | |
3063 | <entry>The service ran successfully and exited cleanly.</entry> | |
3064 | </row> | |
3065 | <row> | |
3066 | <entry><literal>protocol</literal></entry> | |
3067 | <entry>A protocol violation occurred: the service did not take the steps required by its unit configuration (specifically what is configured in its <varname>Type=</varname> setting).</entry> | |
3068 | </row> | |
3069 | <row> | |
3070 | <entry><literal>timeout</literal></entry> | |
3071 | <entry>One of the steps timed out.</entry> | |
3072 | </row> | |
3073 | <row> | |
3074 | <entry><literal>exit-code</literal></entry> | |
3075 | <entry>Service process exited with a non-zero exit code; see <varname>$EXIT_CODE</varname> below for the actual exit code returned.</entry> | |
3076 | </row> | |
3077 | <row> | |
3078 | <entry><literal>signal</literal></entry> | |
3079 | <entry>A service process was terminated abnormally by a signal, without dumping core. See <varname>$EXIT_CODE</varname> below for the actual signal causing the termination.</entry> | |
3080 | </row> | |
3081 | <row> | |
3082 | <entry><literal>core-dump</literal></entry> | |
3083 | <entry>A service process terminated abnormally with a signal and dumped core. See <varname>$EXIT_CODE</varname> below for the signal causing the termination.</entry> | |
3084 | </row> | |
3085 | <row> | |
3086 | <entry><literal>watchdog</literal></entry> | |
3087 | <entry>Watchdog keep-alive ping was enabled for the service, but the deadline was missed.</entry> | |
3088 | </row> | |
3089 | <row> | |
3090 | <entry><literal>start-limit-hit</literal></entry> | |
3091 | <entry>A start limit was defined for the unit and it was hit, causing the unit to fail to start. See <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s <varname>StartLimitIntervalSec=</varname> and <varname>StartLimitBurst=</varname> for details.</entry> | |
3092 | </row> | |
3093 | <row> | |
3094 | <entry><literal>resources</literal></entry> | |
3095 | <entry>A catch-all condition in case a system operation failed.</entry> | |
3096 | </row> | |
3097 | </tbody> | |
3098 | </tgroup> | |
3099 | </table> | |
3100 | ||
3101 | <para>This environment variable is useful to monitor failure or successful termination of a service. Even | |
3102 | though this variable is available in both <varname>ExecStop=</varname> and <varname>ExecStopPost=</varname>, it | |
3103 | is usually a better choice to place monitoring tools in the latter, as the former is only invoked for services | |
3104 | that managed to start up correctly, and the latter covers both services that failed during their start-up and | |
3105 | those which failed during their runtime.</para></listitem> | |
3106 | </varlistentry> | |
3107 | ||
3108 | <varlistentry> | |
3109 | <term><varname>$EXIT_CODE</varname></term> | |
3110 | <term><varname>$EXIT_STATUS</varname></term> | |
3111 | ||
3112 | <listitem><para>Only defined for the service unit type, these environment variables are passed to all | |
3113 | <varname>ExecStop=</varname>, <varname>ExecStopPost=</varname> processes and contain exit status/code | |
3114 | information of the main process of the service. For the precise definition of the exit code and status, see | |
3115 | <citerefentry><refentrytitle>wait</refentrytitle><manvolnum>2</manvolnum></citerefentry>. <varname>$EXIT_CODE</varname> | |
3116 | is one of <literal>exited</literal>, <literal>killed</literal>, | |
3117 | <literal>dumped</literal>. <varname>$EXIT_STATUS</varname> contains the numeric exit code formatted as string | |
3118 | if <varname>$EXIT_CODE</varname> is <literal>exited</literal>, and the signal name in all other cases. Note | |
3119 | that these environment variables are only set if the service manager succeeded to start and identify the main | |
3120 | process of the service.</para> | |
3121 | ||
3122 | <table> | |
3123 | <title>Summary of possible service result variable values</title> | |
3124 | <tgroup cols='3'> | |
3125 | <colspec colname='result' /> | |
3126 | <colspec colname='code' /> | |
3127 | <colspec colname='status' /> | |
3128 | <thead> | |
3129 | <row> | |
3130 | <entry><varname>$SERVICE_RESULT</varname></entry> | |
3131 | <entry><varname>$EXIT_CODE</varname></entry> | |
3132 | <entry><varname>$EXIT_STATUS</varname></entry> | |
3133 | </row> | |
3134 | </thead> | |
3135 | ||
3136 | <tbody> | |
3137 | <row> | |
3138 | <entry morerows="1" valign="top"><literal>success</literal></entry> | |
3139 | <entry valign="top"><literal>killed</literal></entry> | |
3140 | <entry><literal>HUP</literal>, <literal>INT</literal>, <literal>TERM</literal>, <literal>PIPE</literal></entry> | |
3141 | </row> | |
3142 | <row> | |
3143 | <entry valign="top"><literal>exited</literal></entry> | |
3144 | <entry><literal>0</literal></entry> | |
3145 | </row> | |
3146 | <row> | |
3147 | <entry morerows="1" valign="top"><literal>protocol</literal></entry> | |
3148 | <entry valign="top">not set</entry> | |
3149 | <entry>not set</entry> | |
3150 | </row> | |
3151 | <row> | |
3152 | <entry><literal>exited</literal></entry> | |
3153 | <entry><literal>0</literal></entry> | |
3154 | </row> | |
3155 | <row> | |
3156 | <entry morerows="1" valign="top"><literal>timeout</literal></entry> | |
3157 | <entry valign="top"><literal>killed</literal></entry> | |
3158 | <entry><literal>TERM</literal>, <literal>KILL</literal></entry> | |
3159 | </row> | |
3160 | <row> | |
3161 | <entry valign="top"><literal>exited</literal></entry> | |
3162 | <entry><literal>0</literal>, <literal>1</literal>, <literal>2</literal>, <literal | |
3163 | >3</literal>, …, <literal>255</literal></entry> | |
3164 | </row> | |
3165 | <row> | |
3166 | <entry valign="top"><literal>exit-code</literal></entry> | |
3167 | <entry valign="top"><literal>exited</literal></entry> | |
3168 | <entry><literal>1</literal>, <literal>2</literal>, <literal | |
3169 | >3</literal>, …, <literal>255</literal></entry> | |
3170 | </row> | |
3171 | <row> | |
3172 | <entry valign="top"><literal>signal</literal></entry> | |
3173 | <entry valign="top"><literal>killed</literal></entry> | |
3174 | <entry><literal>HUP</literal>, <literal>INT</literal>, <literal>KILL</literal>, …</entry> | |
3175 | </row> | |
3176 | <row> | |
3177 | <entry valign="top"><literal>core-dump</literal></entry> | |
3178 | <entry valign="top"><literal>dumped</literal></entry> | |
3179 | <entry><literal>ABRT</literal>, <literal>SEGV</literal>, <literal>QUIT</literal>, …</entry> | |
3180 | </row> | |
3181 | <row> | |
3182 | <entry morerows="2" valign="top"><literal>watchdog</literal></entry> | |
3183 | <entry><literal>dumped</literal></entry> | |
3184 | <entry><literal>ABRT</literal></entry> | |
3185 | </row> | |
3186 | <row> | |
3187 | <entry><literal>killed</literal></entry> | |
3188 | <entry><literal>TERM</literal>, <literal>KILL</literal></entry> | |
3189 | </row> | |
3190 | <row> | |
3191 | <entry><literal>exited</literal></entry> | |
3192 | <entry><literal>0</literal>, <literal>1</literal>, <literal>2</literal>, <literal | |
3193 | >3</literal>, …, <literal>255</literal></entry> | |
3194 | </row> | |
3195 | <row> | |
3196 | <entry valign="top"><literal>exec-condition</literal></entry> | |
3197 | <entry><literal>exited</literal></entry> | |
3198 | <entry><literal>1</literal>, <literal>2</literal>, <literal>3</literal>, <literal | |
3199 | >4</literal>, …, <literal>254</literal></entry> | |
3200 | </row> | |
3201 | <row> | |
3202 | <entry valign="top"><literal>oom-kill</literal></entry> | |
3203 | <entry valign="top"><literal>killed</literal></entry> | |
3204 | <entry><literal>TERM</literal>, <literal>KILL</literal></entry> | |
3205 | </row> | |
3206 | <row> | |
3207 | <entry><literal>start-limit-hit</literal></entry> | |
3208 | <entry>not set</entry> | |
3209 | <entry>not set</entry> | |
3210 | </row> | |
3211 | <row> | |
3212 | <entry><literal>resources</literal></entry> | |
3213 | <entry>any of the above</entry> | |
3214 | <entry>any of the above</entry> | |
3215 | </row> | |
3216 | <row> | |
3217 | <entry namest="results" nameend="status">Note: the process may be also terminated by a signal not sent by systemd. In particular the process may send an arbitrary signal to itself in a handler for any of the non-maskable signals. Nevertheless, in the <literal>timeout</literal> and <literal>watchdog</literal> rows above only the signals that systemd sends have been included. Moreover, using <varname>SuccessExitStatus=</varname> additional exit statuses may be declared to indicate clean termination, which is not reflected by this table.</entry> | |
3218 | </row> | |
3219 | </tbody> | |
3220 | </tgroup> | |
3221 | </table></listitem> | |
3222 | </varlistentry> | |
3223 | ||
3224 | <varlistentry> | |
3225 | <term><varname>$PIDFILE</varname></term> | |
3226 | ||
3227 | <listitem><para>The path to the configured PID file, in case the process is forked off on behalf of | |
3228 | a service that uses the <varname>PIDFile=</varname> setting, see | |
3229 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
3230 | for details. Service code may use this environment variable to automatically generate a PID file at | |
3231 | the location configured in the unit file. This field is set to an absolute path in the file | |
3232 | system.</para></listitem> | |
3233 | </varlistentry> | |
3234 | ||
3235 | </variablelist> | |
3236 | ||
3237 | <para>For system services, when <varname>PAMName=</varname> is enabled and <command>pam_systemd</command> is part | |
3238 | of the selected PAM stack, additional environment variables defined by systemd may be set for | |
3239 | services. Specifically, these are <varname>$XDG_SEAT</varname>, <varname>$XDG_VTNR</varname>, see | |
3240 | <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> for details.</para> | |
3241 | </refsect2> | |
46b07329 | 3242 | |
798d3a52 ZJS |
3243 | </refsect1> |
3244 | ||
91a8f867 | 3245 | <refsect1> |
82651d5b | 3246 | <title>Process Exit Codes</title> |
91a8f867 JS |
3247 | |
3248 | <para>When invoking a unit process the service manager possibly fails to apply the execution parameters configured | |
3249 | with the settings above. In that case the already created service process will exit with a non-zero exit code | |
3250 | before the configured command line is executed. (Or in other words, the child process possibly exits with these | |
3251 | error codes, after having been created by the <citerefentry | |
3252 | project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry> system call, but | |
3253 | before the matching <citerefentry | |
3254 | project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry> system call is | |
3255 | called.) Specifically, exit codes defined by the C library, by the LSB specification and by the systemd service | |
3256 | manager itself are used.</para> | |
3257 | ||
3258 | <para>The following basic service exit codes are defined by the C library.</para> | |
3259 | ||
3260 | <table> | |
3261 | <title>Basic C library exit codes</title> | |
3262 | <tgroup cols='3'> | |
3263 | <thead> | |
3264 | <row> | |
3265 | <entry>Exit Code</entry> | |
3266 | <entry>Symbolic Name</entry> | |
3267 | <entry>Description</entry> | |
3268 | </row> | |
3269 | </thead> | |
3270 | <tbody> | |
3271 | <row> | |
3272 | <entry>0</entry> | |
3273 | <entry><constant>EXIT_SUCCESS</constant></entry> | |
3274 | <entry>Generic success code.</entry> | |
3275 | </row> | |
3276 | <row> | |
3277 | <entry>1</entry> | |
3278 | <entry><constant>EXIT_FAILURE</constant></entry> | |
3279 | <entry>Generic failure or unspecified error.</entry> | |
3280 | </row> | |
3281 | </tbody> | |
3282 | </tgroup> | |
3283 | </table> | |
3284 | ||
3285 | <para>The following service exit codes are defined by the <ulink | |
29a3d5ca | 3286 | url="https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html">LSB specification</ulink>. |
91a8f867 JS |
3287 | </para> |
3288 | ||
3289 | <table> | |
3290 | <title>LSB service exit codes</title> | |
3291 | <tgroup cols='3'> | |
3292 | <thead> | |
3293 | <row> | |
3294 | <entry>Exit Code</entry> | |
3295 | <entry>Symbolic Name</entry> | |
3296 | <entry>Description</entry> | |
3297 | </row> | |
3298 | </thead> | |
3299 | <tbody> | |
3300 | <row> | |
3301 | <entry>2</entry> | |
3302 | <entry><constant>EXIT_INVALIDARGUMENT</constant></entry> | |
3303 | <entry>Invalid or excess arguments.</entry> | |
3304 | </row> | |
3305 | <row> | |
3306 | <entry>3</entry> | |
3307 | <entry><constant>EXIT_NOTIMPLEMENTED</constant></entry> | |
3308 | <entry>Unimplemented feature.</entry> | |
3309 | </row> | |
3310 | <row> | |
3311 | <entry>4</entry> | |
3312 | <entry><constant>EXIT_NOPERMISSION</constant></entry> | |
3313 | <entry>The user has insufficient privileges.</entry> | |
3314 | </row> | |
3315 | <row> | |
3316 | <entry>5</entry> | |
3317 | <entry><constant>EXIT_NOTINSTALLED</constant></entry> | |
3318 | <entry>The program is not installed.</entry> | |
3319 | </row> | |
3320 | <row> | |
3321 | <entry>6</entry> | |
3322 | <entry><constant>EXIT_NOTCONFIGURED</constant></entry> | |
3323 | <entry>The program is not configured.</entry> | |
3324 | </row> | |
3325 | <row> | |
3326 | <entry>7</entry> | |
3327 | <entry><constant>EXIT_NOTRUNNING</constant></entry> | |
3328 | <entry>The program is not running.</entry> | |
3329 | </row> | |
3330 | </tbody> | |
3331 | </tgroup> | |
3332 | </table> | |
3333 | ||
3334 | <para> | |
3335 | The LSB specification suggests that error codes 200 and above are reserved for implementations. Some of them are | |
3336 | used by the service manager to indicate problems during process invocation: | |
3337 | </para> | |
3338 | <table> | |
3339 | <title>systemd-specific exit codes</title> | |
3340 | <tgroup cols='3'> | |
3341 | <thead> | |
3342 | <row> | |
3343 | <entry>Exit Code</entry> | |
3344 | <entry>Symbolic Name</entry> | |
3345 | <entry>Description</entry> | |
3346 | </row> | |
3347 | </thead> | |
3348 | <tbody> | |
3349 | <row> | |
3350 | <entry>200</entry> | |
3351 | <entry><constant>EXIT_CHDIR</constant></entry> | |
3352 | <entry>Changing to the requested working directory failed. See <varname>WorkingDirectory=</varname> above.</entry> | |
3353 | </row> | |
3354 | <row> | |
3355 | <entry>201</entry> | |
3356 | <entry><constant>EXIT_NICE</constant></entry> | |
3357 | <entry>Failed to set up process scheduling priority (nice level). See <varname>Nice=</varname> above.</entry> | |
3358 | </row> | |
3359 | <row> | |
3360 | <entry>202</entry> | |
3361 | <entry><constant>EXIT_FDS</constant></entry> | |
3362 | <entry>Failed to close unwanted file descriptors, or to adjust passed file descriptors.</entry> | |
3363 | </row> | |
3364 | <row> | |
3365 | <entry>203</entry> | |
3366 | <entry><constant>EXIT_EXEC</constant></entry> | |
3367 | <entry>The actual process execution failed (specifically, the <citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry> system call). Most likely this is caused by a missing or non-accessible executable file.</entry> | |
3368 | </row> | |
3369 | <row> | |
3370 | <entry>204</entry> | |
3371 | <entry><constant>EXIT_MEMORY</constant></entry> | |
3372 | <entry>Failed to perform an action due to memory shortage.</entry> | |
3373 | </row> | |
3374 | <row> | |
3375 | <entry>205</entry> | |
3376 | <entry><constant>EXIT_LIMITS</constant></entry> | |
dcfaecc7 | 3377 | <entry>Failed to adjust resource limits. See <varname>LimitCPU=</varname> and related settings above.</entry> |
91a8f867 JS |
3378 | </row> |
3379 | <row> | |
3380 | <entry>206</entry> | |
3381 | <entry><constant>EXIT_OOM_ADJUST</constant></entry> | |
3382 | <entry>Failed to adjust the OOM setting. See <varname>OOMScoreAdjust=</varname> above.</entry> | |
3383 | </row> | |
3384 | <row> | |
3385 | <entry>207</entry> | |
3386 | <entry><constant>EXIT_SIGNAL_MASK</constant></entry> | |
3387 | <entry>Failed to set process signal mask.</entry> | |
3388 | </row> | |
3389 | <row> | |
3390 | <entry>208</entry> | |
3391 | <entry><constant>EXIT_STDIN</constant></entry> | |
3392 | <entry>Failed to set up standard input. See <varname>StandardInput=</varname> above.</entry> | |
3393 | </row> | |
3394 | <row> | |
3395 | <entry>209</entry> | |
3396 | <entry><constant>EXIT_STDOUT</constant></entry> | |
3397 | <entry>Failed to set up standard output. See <varname>StandardOutput=</varname> above.</entry> | |
3398 | </row> | |
3399 | <row> | |
3400 | <entry>210</entry> | |
3401 | <entry><constant>EXIT_CHROOT</constant></entry> | |
3402 | <entry>Failed to change root directory (<citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>). See <varname>RootDirectory=</varname>/<varname>RootImage=</varname> above.</entry> | |
3403 | </row> | |
3404 | <row> | |
3405 | <entry>211</entry> | |
3406 | <entry><constant>EXIT_IOPRIO</constant></entry> | |
3407 | <entry>Failed to set up IO scheduling priority. See <varname>IOSchedulingClass=</varname>/<varname>IOSchedulingPriority=</varname> above.</entry> | |
3408 | </row> | |
3409 | <row> | |
3410 | <entry>212</entry> | |
3411 | <entry><constant>EXIT_TIMERSLACK</constant></entry> | |
3412 | <entry>Failed to set up timer slack. See <varname>TimerSlackNSec=</varname> above.</entry> | |
3413 | </row> | |
3414 | <row> | |
3415 | <entry>213</entry> | |
3416 | <entry><constant>EXIT_SECUREBITS</constant></entry> | |
3417 | <entry>Failed to set process secure bits. See <varname>SecureBits=</varname> above.</entry> | |
3418 | </row> | |
3419 | <row> | |
3420 | <entry>214</entry> | |
3421 | <entry><constant>EXIT_SETSCHEDULER</constant></entry> | |
3422 | <entry>Failed to set up CPU scheduling. See <varname>CPUSchedulingPolicy=</varname>/<varname>CPUSchedulingPriority=</varname> above.</entry> | |
3423 | </row> | |
3424 | <row> | |
3425 | <entry>215</entry> | |
3426 | <entry><constant>EXIT_CPUAFFINITY</constant></entry> | |
3427 | <entry>Failed to set up CPU affinity. See <varname>CPUAffinity=</varname> above.</entry> | |
3428 | </row> | |
3429 | <row> | |
3430 | <entry>216</entry> | |
3431 | <entry><constant>EXIT_GROUP</constant></entry> | |
3432 | <entry>Failed to determine or change group credentials. See <varname>Group=</varname>/<varname>SupplementaryGroups=</varname> above.</entry> | |
3433 | </row> | |
3434 | <row> | |
3435 | <entry>217</entry> | |
3436 | <entry><constant>EXIT_USER</constant></entry> | |
3437 | <entry>Failed to determine or change user credentials, or to set up user namespacing. See <varname>User=</varname>/<varname>PrivateUsers=</varname> above.</entry> | |
3438 | </row> | |
3439 | <row> | |
3440 | <entry>218</entry> | |
3441 | <entry><constant>EXIT_CAPABILITIES</constant></entry> | |
3442 | <entry>Failed to drop capabilities, or apply ambient capabilities. See <varname>CapabilityBoundingSet=</varname>/<varname>AmbientCapabilities=</varname> above.</entry> | |
3443 | </row> | |
3444 | <row> | |
3445 | <entry>219</entry> | |
3446 | <entry><constant>EXIT_CGROUP</constant></entry> | |
3447 | <entry>Setting up the service control group failed.</entry> | |
3448 | </row> | |
3449 | <row> | |
3450 | <entry>220</entry> | |
3451 | <entry><constant>EXIT_SETSID</constant></entry> | |
3452 | <entry>Failed to create new process session.</entry> | |
3453 | </row> | |
3454 | <row> | |
3455 | <entry>221</entry> | |
3456 | <entry><constant>EXIT_CONFIRM</constant></entry> | |
3457 | <entry>Execution has been cancelled by the user. See the <varname>systemd.confirm_spawn=</varname> kernel command line setting on <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details.</entry> | |
3458 | </row> | |
3459 | <row> | |
3460 | <entry>222</entry> | |
3461 | <entry><constant>EXIT_STDERR</constant></entry> | |
3462 | <entry>Failed to set up standard error output. See <varname>StandardError=</varname> above.</entry> | |
3463 | </row> | |
3464 | <row> | |
3465 | <entry>224</entry> | |
3466 | <entry><constant>EXIT_PAM</constant></entry> | |
3467 | <entry>Failed to set up PAM session. See <varname>PAMName=</varname> above.</entry> | |
3468 | </row> | |
3469 | <row> | |
3470 | <entry>225</entry> | |
3471 | <entry><constant>EXIT_NETWORK</constant></entry> | |
3472 | <entry>Failed to set up network namespacing. See <varname>PrivateNetwork=</varname> above.</entry> | |
3473 | </row> | |
3474 | <row> | |
3475 | <entry>226</entry> | |
3476 | <entry><constant>EXIT_NAMESPACE</constant></entry> | |
3477 | <entry>Failed to set up mount namespacing. See <varname>ReadOnlyPaths=</varname> and related settings above.</entry> | |
3478 | </row> | |
3479 | <row> | |
3480 | <entry>227</entry> | |
3481 | <entry><constant>EXIT_NO_NEW_PRIVILEGES</constant></entry> | |
dcfaecc7 | 3482 | <entry>Failed to disable new privileges. See <varname>NoNewPrivileges=yes</varname> above.</entry> |
91a8f867 JS |
3483 | </row> |
3484 | <row> | |
3485 | <entry>228</entry> | |
3486 | <entry><constant>EXIT_SECCOMP</constant></entry> | |
3487 | <entry>Failed to apply system call filters. See <varname>SystemCallFilter=</varname> and related settings above.</entry> | |
3488 | </row> | |
3489 | <row> | |
3490 | <entry>229</entry> | |
3491 | <entry><constant>EXIT_SELINUX_CONTEXT</constant></entry> | |
3492 | <entry>Determining or changing SELinux context failed. See <varname>SELinuxContext=</varname> above.</entry> | |
3493 | </row> | |
3494 | <row> | |
3495 | <entry>230</entry> | |
3496 | <entry><constant>EXIT_PERSONALITY</constant></entry> | |
dcfaecc7 | 3497 | <entry>Failed to set up an execution domain (personality). See <varname>Personality=</varname> above.</entry> |
91a8f867 JS |
3498 | </row> |
3499 | <row> | |
3500 | <entry>231</entry> | |
3501 | <entry><constant>EXIT_APPARMOR_PROFILE</constant></entry> | |
3502 | <entry>Failed to prepare changing AppArmor profile. See <varname>AppArmorProfile=</varname> above.</entry> | |
3503 | </row> | |
3504 | <row> | |
3505 | <entry>232</entry> | |
3506 | <entry><constant>EXIT_ADDRESS_FAMILIES</constant></entry> | |
3507 | <entry>Failed to restrict address families. See <varname>RestrictAddressFamilies=</varname> above.</entry> | |
3508 | </row> | |
3509 | <row> | |
3510 | <entry>233</entry> | |
3511 | <entry><constant>EXIT_RUNTIME_DIRECTORY</constant></entry> | |
3512 | <entry>Setting up runtime directory failed. See <varname>RuntimeDirectory=</varname> and related settings above.</entry> | |
3513 | </row> | |
3514 | <row> | |
3515 | <entry>235</entry> | |
3516 | <entry><constant>EXIT_CHOWN</constant></entry> | |
3517 | <entry>Failed to adjust socket ownership. Used for socket units only.</entry> | |
3518 | </row> | |
3519 | <row> | |
3520 | <entry>236</entry> | |
3521 | <entry><constant>EXIT_SMACK_PROCESS_LABEL</constant></entry> | |
3522 | <entry>Failed to set SMACK label. See <varname>SmackProcessLabel=</varname> above.</entry> | |
3523 | </row> | |
3524 | <row> | |
3525 | <entry>237</entry> | |
3526 | <entry><constant>EXIT_KEYRING</constant></entry> | |
3527 | <entry>Failed to set up kernel keyring.</entry> | |
3528 | </row> | |
3529 | <row> | |
3530 | <entry>238</entry> | |
3531 | <entry><constant>EXIT_STATE_DIRECTORY</constant></entry> | |
dcfaecc7 | 3532 | <entry>Failed to set up unit's state directory. See <varname>StateDirectory=</varname> above.</entry> |
91a8f867 JS |
3533 | </row> |
3534 | <row> | |
3535 | <entry>239</entry> | |
3536 | <entry><constant>EXIT_CACHE_DIRECTORY</constant></entry> | |
dcfaecc7 | 3537 | <entry>Failed to set up unit's cache directory. See <varname>CacheDirectory=</varname> above.</entry> |
91a8f867 JS |
3538 | </row> |
3539 | <row> | |
3540 | <entry>240</entry> | |
3541 | <entry><constant>EXIT_LOGS_DIRECTORY</constant></entry> | |
dcfaecc7 | 3542 | <entry>Failed to set up unit's logging directory. See <varname>LogsDirectory=</varname> above.</entry> |
91a8f867 JS |
3543 | </row> |
3544 | <row> | |
3545 | <entry>241</entry> | |
3546 | <entry><constant>EXIT_CONFIGURATION_DIRECTORY</constant></entry> | |
dcfaecc7 | 3547 | <entry>Failed to set up unit's configuration directory. See <varname>ConfigurationDirectory=</varname> above.</entry> |
91a8f867 | 3548 | </row> |
b070c7c0 MS |
3549 | <row> |
3550 | <entry>242</entry> | |
3551 | <entry><constant>EXIT_NUMA_POLICY</constant></entry> | |
e9dd6984 | 3552 | <entry>Failed to set up unit's NUMA memory policy. See <varname>NUMAPolicy=</varname> and <varname>NUMAMask=</varname> above.</entry> |
b070c7c0 | 3553 | </row> |
3220cf39 LP |
3554 | <row> |
3555 | <entry>243</entry> | |
3556 | <entry><constant>EXIT_CREDENTIALS</constant></entry> | |
3557 | <entry>Failed to set up unit's credentials. See <varname>LoadCredential=</varname> and <varname>SetCredential=</varname> above.</entry> | |
3558 | </row> | |
91a8f867 JS |
3559 | </tbody> |
3560 | </tgroup> | |
3561 | </table> | |
3e0bff7d LP |
3562 | |
3563 | <para>Finally, the BSD operating systems define a set of exit codes, typically defined on Linux systems too:</para> | |
3564 | ||
3565 | <table> | |
3566 | <title>BSD exit codes</title> | |
3567 | <tgroup cols='3'> | |
3568 | <thead> | |
3569 | <row> | |
3570 | <entry>Exit Code</entry> | |
3571 | <entry>Symbolic Name</entry> | |
3572 | <entry>Description</entry> | |
3573 | </row> | |
3574 | </thead> | |
3575 | <tbody> | |
3576 | <row> | |
3577 | <entry>64</entry> | |
3578 | <entry><constant>EX_USAGE</constant></entry> | |
3579 | <entry>Command line usage error</entry> | |
3580 | </row> | |
3581 | <row> | |
3582 | <entry>65</entry> | |
3583 | <entry><constant>EX_DATAERR</constant></entry> | |
3584 | <entry>Data format error</entry> | |
3585 | </row> | |
3586 | <row> | |
3587 | <entry>66</entry> | |
3588 | <entry><constant>EX_NOINPUT</constant></entry> | |
3589 | <entry>Cannot open input</entry> | |
3590 | </row> | |
3591 | <row> | |
3592 | <entry>67</entry> | |
3593 | <entry><constant>EX_NOUSER</constant></entry> | |
3594 | <entry>Addressee unknown</entry> | |
3595 | </row> | |
3596 | <row> | |
3597 | <entry>68</entry> | |
3598 | <entry><constant>EX_NOHOST</constant></entry> | |
3599 | <entry>Host name unknown</entry> | |
3600 | </row> | |
3601 | <row> | |
3602 | <entry>69</entry> | |
3603 | <entry><constant>EX_UNAVAILABLE</constant></entry> | |
3604 | <entry>Service unavailable</entry> | |
3605 | </row> | |
3606 | <row> | |
3607 | <entry>70</entry> | |
3608 | <entry><constant>EX_SOFTWARE</constant></entry> | |
3609 | <entry>internal software error</entry> | |
3610 | </row> | |
3611 | <row> | |
3612 | <entry>71</entry> | |
3613 | <entry><constant>EX_OSERR</constant></entry> | |
3614 | <entry>System error (e.g., can't fork)</entry> | |
3615 | </row> | |
3616 | <row> | |
3617 | <entry>72</entry> | |
3618 | <entry><constant>EX_OSFILE</constant></entry> | |
3619 | <entry>Critical OS file missing</entry> | |
3620 | </row> | |
3621 | <row> | |
3622 | <entry>73</entry> | |
3623 | <entry><constant>EX_CANTCREAT</constant></entry> | |
3624 | <entry>Can't create (user) output file</entry> | |
3625 | </row> | |
3626 | <row> | |
3627 | <entry>74</entry> | |
3628 | <entry><constant>EX_IOERR</constant></entry> | |
3629 | <entry>Input/output error</entry> | |
3630 | </row> | |
3631 | <row> | |
3632 | <entry>75</entry> | |
3633 | <entry><constant>EX_TEMPFAIL</constant></entry> | |
3634 | <entry>Temporary failure; user is invited to retry</entry> | |
3635 | </row> | |
3636 | <row> | |
3637 | <entry>76</entry> | |
3638 | <entry><constant>EX_PROTOCOL</constant></entry> | |
3639 | <entry>Remote error in protocol</entry> | |
3640 | </row> | |
3641 | <row> | |
3642 | <entry>77</entry> | |
3643 | <entry><constant>EX_NOPERM</constant></entry> | |
3644 | <entry>Permission denied</entry> | |
3645 | </row> | |
3646 | <row> | |
3647 | <entry>78</entry> | |
3648 | <entry><constant>EX_CONFIG</constant></entry> | |
3649 | <entry>Configuration error</entry> | |
3650 | </row> | |
3651 | </tbody> | |
3652 | </tgroup> | |
3653 | </table> | |
91a8f867 JS |
3654 | </refsect1> |
3655 | ||
798d3a52 ZJS |
3656 | <refsect1> |
3657 | <title>See Also</title> | |
3658 | <para> | |
3659 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
3660 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
869feb33 | 3661 | <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
68d838f7 | 3662 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
d1698b82 | 3663 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
798d3a52 ZJS |
3664 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
3665 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3666 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3667 | <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3668 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3669 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3670 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
a4c18002 | 3671 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
798d3a52 ZJS |
3672 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
3673 | <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
0b4d17c9 ZJS |
3674 | <citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
3675 | <citerefentry project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
798d3a52 ZJS |
3676 | </para> |
3677 | </refsect1> | |
dd1eb43b LP |
3678 | |
3679 | </refentry> |