1SUDO.CONF(5) BSD File Formats Manual SUDO.CONF(5)
2
4 sudo.conf — configuration for sudo front end
5
7 The sudo.conf file is used to configure the sudo front end. It specifies
8 the security policy and I/O logging plugins, debug flags as well as
9 plugin-agnostic path names and settings.
10 The sudo.conf file supports the following directives, described in detail
12 below.
13 Plugin a security policy or I/O logging plugin
15 Path a plugin-agnostic path
17 Set a front end setting, such as disable_coredump or group_source
19 Debug debug flags to aid in debugging sudo, sudoreplay, visudo, and
21 the sudoers plugin.
22 The pound sign (‘#’) is used to indicate a comment. Both the comment
24 character and any text after it, up to the end of the line, are ignored.
25 Long lines can be continued with a backslash (‘\’) as the last character
27 on the line. Note that leading white space is removed from the beginning
28 of lines even when the continuation character is used.
29 Non-comment lines that don't begin with Plugin, Path, Debug, or Set are
31 silently ignored.
32 The sudo.conf file is always parsed in the “C” locale.
34 Plugin configuration
36 sudo supports a plugin architecture for security policies and input/out‐
37 put logging. Third parties can develop and distribute their own policy
38 and I/O logging plugins to work seamlessly with the sudo front end.
39 Plugins are dynamically loaded based on the contents of sudo.conf.
40 A Plugin line consists of the Plugin keyword, followed by the symbol_name
42 and the path to the dynamic shared object that contains the plugin. The
43 symbol_name is the name of the approval_plugin, audit_plugin, io_plugin,
44 or policy_plugin struct contained in the plugin. If a plugin implements
45 multiple plugin types, there must be a Plugin line for each unique symbol
46 name. The path may be fully qualified or relative. If not fully quali‐
47 fied, it is relative to the directory specified by the plugin_dir Path
48 setting, which defaults to /usr/libexec/sudo. In other words:
49 Plugin sudoers_policy sudoers.so
51 is equivalent to:
53 Plugin sudoers_policy /usr/libexec/sudo/sudoers.so
55 If the plugin was compiled statically into the sudo binary instead of be‐
57 ing installed as a dynamic shared object, the path should be specified
58 without a leading directory, as it does not actually exist in the file
59 system. For example:
60 Plugin sudoers_policy sudoers.so
62 Starting with sudo 1.8.5, any additional parameters after the path are
64 passed as arguments to the plugin's open function. For example, to over‐
65 ride the compile-time default sudoers file mode:
66 Plugin sudoers_policy sudoers.so sudoers_mode=0440
68 See the sudoers(5) manual for a list of supported arguments.
70 The same dynamic shared object may contain multiple plugins, each with a
72 different symbol name. The file must be owned by uid 0 and only writable
73 by its owner. Because of ambiguities that arise from composite policies,
74 only a single policy plugin may be specified. This limitation does not
75 apply to I/O plugins.
76 If no sudo.conf file is present, or if it contains no Plugin lines, the
78 sudoers plugin will be used as the default security policy, for I/O log‐
79 ging (if enabled by the policy) and for auditing. This is equivalent to
80 the following:
81 Plugin sudoers_policy sudoers.so
83 Plugin sudoers_io sudoers.so
84 Plugin sudoers_audit sudoers.so
85 Starting with sudo version 1.9.1, some of the logging functionality of
87 the sudoers plugin has been moved from the policy plugin to an audit
88 plugin. To maintain compatibility with sudo.conf files from older sudo
89 versions, if sudoers is configured as the security policy, it will be
90 used as an audit plugin as well. This guarantees that the logging behav‐
91 ior will be consistnet with that of sudo versions 1.9.0 and below.
92 For more information on the sudo plugin architecture, see the
94 sudo_plugin(5) manual.
95 Path settings
97 A Path line consists of the Path keyword, followed by the name of the
98 path to set and its value. For example:
99 Path noexec /usr/libexec/sudo/sudo_noexec.so
101 Path askpass /usr/X11R6/bin/ssh-askpass
102 If no path name is specified, features relying on the specified setting
104 will be disabled. Disabling Path settings is only supported in sudo ver‐
105 sion 1.8.16 and higher.
106 The following plugin-agnostic paths may be set in the /etc/sudo.conf
108 file:
109 askpass The fully qualified path to a helper program used to read the
111 user's password when no terminal is available. This may be the
112 case when sudo is executed from a graphical (as opposed to
113 text-based) application. The program specified by askpass
114 should display the argument passed to it as the prompt and
115 write the user's password to the standard output. The value of
116 askpass may be overridden by the SUDO_ASKPASS environment vari‐
117 able.
118 devsearch
120 An ordered, colon-separated search path of directories to look
121 in for device nodes. This is used when mapping the process's
122 tty device number to a device name on systems that do not pro‐
123 vide such a mechanism. Sudo will not recurse into sub-directo‐
124 ries. If terminal devices may be located in a sub-directory of
125 /dev, that path must be explicitly listed in devsearch. The
126 default value is
127 /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev
128 This option is ignored on systems that support either the
130 devname() or _ttyname_dev() functions, for example BSD, macOS
131 and Solaris.
132 noexec The fully-qualified path to a shared library containing wrap‐
134 pers for the execl(), execle(), execlp(), exect(), execv(),
135 execve(), execvP(), execvp(), execvpe(), fexecve(), popen(),
136 posix_spawn(), posix_spawnp(), system(), and wordexp() library
137 functions that prevent the execution of further commands. This
138 is used to implement the noexec functionality on systems that
139 support LD_PRELOAD or its equivalent. The default value is
140 /usr/libexec/sudo/sudo_noexec.so.
141 plugin_dir
143 The default directory to use when searching for plugins that
144 are specified without a fully qualified path name. The default
145 value is /usr/libexec/sudo.
146 sesh The fully-qualified path to the sesh binary. This setting is
148 only used when sudo is built with SELinux support. The default
149 value is /usr/libexec/sudo/sesh.
150 Other settings
152 The sudo.conf file also supports the following front end settings:
153 disable_coredump
155 Core dumps of sudo itself are disabled by default to prevent
156 the disclosure of potentially sensitive information. To aid in
157 debugging sudo crashes, you may wish to re-enable core dumps by
158 setting “disable_coredump” to false in sudo.conf as follows:
159 Set disable_coredump false
161 All modern operating systems place restrictions on core dumps
163 from set-user-ID processes like sudo so this option can be en‐
164 abled without compromising security. To actually get a sudo
165 core file you will likely need to enable core dumps for set-
166 user-ID processes. On BSD and Linux systems this is accom‐
167 plished in the sysctl(8) command. On Solaris, the coreadm(1m)
168 command is used to configure core dump behavior.
169 This setting is only available in sudo version 1.8.4 and
171 higher.
172 developer_mode
174 By default sudo refuses to load plugins which can be modified
175 by other than the root user. The plugin should be owned by
176 root and write access permissions should be disabled for
177 “group” and “other”. To make development of a plugin easier,
178 you can disable that by setting “developer_mode” option to true
179 in sudo.conf as follows:
180 Set developer_mode true
182 Please note that this creates a security risk, so it is not
184 recommended on critical systems such as a desktop machine for
185 daily use, but is intended to be used in development environ‐
186 ments (VM, container, etc). Before enabling developer mode,
187 ensure you understand the implications.
188 This setting is only available in sudo version 1.9.0 and
190 higher.
191 group_source
193 sudo passes the invoking user's group list to the policy and
194 I/O plugins. On most systems, there is an upper limit to the
195 number of groups that a user may belong to simultaneously (typ‐
196 ically 16 for compatibility with NFS). On systems with the
197 getconf(1) utility, running:
198 getconf NGROUPS_MAX
199 will return the maximum number of groups.
200 However, it is still possible to be a member of a larger number
202 of groups--they simply won't be included in the group list re‐
203 turned by the kernel for the user. Starting with sudo version
204 1.8.7, if the user's kernel group list has the maximum number
205 of entries, sudo will consult the group database directly to
206 determine the group list. This makes it possible for the secu‐
207 rity policy to perform matching by group name even when the
208 user is a member of more than the maximum number of groups.
209 The group_source setting allows the administrator to change
211 this default behavior. Supported values for group_source are:
212 static Use the static group list that the kernel returns.
214 Retrieving the group list this way is very fast but
215 it is subject to an upper limit as described above.
216 It is “static” in that it does not reflect changes to
217 the group database made after the user logs in. This
218 was the default behavior prior to sudo 1.8.7.
219 dynamic Always query the group database directly. It is
221 “dynamic” in that changes made to the group database
222 after the user logs in will be reflected in the group
223 list. On some systems, querying the group database
224 for all of a user's groups can be time consuming when
225 querying a network-based group database. Most oper‐
226 ating systems provide an efficient method of perform‐
227 ing such queries. Currently, sudo supports efficient
228 group queries on AIX, BSD, HP-UX, Linux, macOS and
229 Solaris. This is the default behavior on macOS in
230 sudo 1.9.6 and higher.
231 adaptive Only query the group database if the static group
233 list returned by the kernel has the maximum number of
234 entries. This is the default behavior on systems
235 other than macOS in sudo 1.8.7 and higher.
236 For example, to cause sudo to only use the kernel's static list
238 of groups for the user:
239 Set group_source static
241 This setting is only available in sudo version 1.8.7 and
243 higher.
244 max_groups
246 The maximum number of user groups to retrieve from the group
247 database. Values less than one or larger than 1024 will be ig‐
248 nored. This setting is only used when querying the group data‐
249 base directly. It is intended to be used on systems where it
250 is not possible to detect when the array to be populated with
251 group entries is not sufficiently large. By default, sudo will
252 allocate four times the system's maximum number of groups (see
253 above) and retry with double that number if the group database
254 query fails.
255 This setting is only available in sudo version 1.8.7 and
257 higher. It should not be required in sudo versions 1.8.24 and
258 higher and may be removed in a later release.
259 probe_interfaces
261 By default, sudo will probe the system's network interfaces and
262 pass the IP address of each enabled interface to the policy
263 plugin. This makes it possible for the plugin to match rules
264 based on the IP address without having to query DNS. On Linux
265 systems with a large number of virtual interfaces, this may
266 take a non-negligible amount of time. If IP-based matching is
267 not required, network interface probing can be disabled as fol‐
268 lows:
269 Set probe_interfaces false
271 This setting is only available in sudo version 1.8.10 and
273 higher.
274 Debug flags
276 sudo versions 1.8.4 and higher support a flexible debugging framework
277 that can help track down what sudo is doing internally if there is a
278 problem.
279 A Debug line consists of the Debug keyword, followed by the name of the
281 program (or plugin) to debug (sudo, visudo, sudoreplay, sudoers), the de‐
282 bug file name and a comma-separated list of debug flags. The debug flag
283 syntax used by sudo and the sudoers plugin is subsystem@priority but a
284 plugin is free to use a different format so long as it does not include a
285 comma (‘,’).
286 For example:
288 Debug sudo /var/log/sudo_debug all@warn,plugin@info
290 would log all debugging statements at the warn level and higher in addi‐
292 tion to those at the info level for the plugin subsystem.
293 As of sudo 1.8.12, multiple Debug entries may be specified per program.
295 Older versions of sudo only support a single Debug entry per program.
296 Plugin-specific Debug entries are also supported starting with sudo
297 1.8.12 and are matched by either the base name of the plugin that was
298 loaded (for example sudoers.so) or by the plugin's fully-qualified path
299 name. Previously, the sudoers plugin shared the same Debug entry as the
300 sudo front end and could not be configured separately.
301 The following priorities are supported, in order of decreasing severity:
303 crit, err, warn, notice, diag, info, trace and debug. Each priority,
304 when specified, also includes all priorities higher than it. For exam‐
305 ple, a priority of notice would include debug messages logged at notice
306 and higher.
307 The priorities trace and debug also include function call tracing which
309 logs when a function is entered and when it returns. For example, the
310 following trace is for the get_user_groups() function located in
311 src/sudo.c:
312 sudo[123] -> get_user_groups @ src/sudo.c:385
314 sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5
315 When the function is entered, indicated by a right arrow ‘->’, the pro‐
317 gram, process ID, function, source file and line number are logged. When
318 the function returns, indicated by a left arrow ‘<-’, the same informa‐
319 tion is logged along with the return value. In this case, the return
320 value is a string.
321 The following subsystems are used by the sudo front-end:
323 all matches every subsystem
325 args command line argument processing
327 conv user conversation
329 edit sudoedit
331 event event subsystem
333 exec command execution
335 main sudo main function
337 netif network interface handling
339 pcomm communication with the plugin
341 plugin plugin configuration
343 pty pseudo-terminal related code
345 selinux SELinux-specific handling
347 util utility functions
349 utmp utmp handling
351 The sudoers(5) plugin includes support for additional subsystems.
353
355 /etc/sudo.conf sudo front end configuration
356
358 #
359 # Default /etc/sudo.conf file
360 #
361 # Sudo plugins:
362 # Plugin plugin_name plugin_path plugin_options ...
363 #
364 # The plugin_path is relative to /usr/libexec/sudo unless
365 # fully qualified.
366 # The plugin_name corresponds to a global symbol in the plugin
367 # that contains the plugin interface structure.
368 # The plugin_options are optional.
369 #
370 # The sudoers plugin is used by default if no Plugin lines are present.
371 #Plugin sudoers_policy sudoers.so
372 #Plugin sudoers_io sudoers.so
373 #Plugin sudoers_audit sudoers.so
374 #
376 # Sudo askpass:
377 # Path askpass /path/to/askpass
378 #
379 # An askpass helper program may be specified to provide a graphical
380 # password prompt for "sudo -A" support. Sudo does not ship with its
381 # own askpass program but can use the OpenSSH askpass.
382 #
383 # Use the OpenSSH askpass
384 #Path askpass /usr/X11R6/bin/ssh-askpass
385 #
386 # Use the Gnome OpenSSH askpass
387 #Path askpass /usr/libexec/openssh/gnome-ssh-askpass
388 #
390 # Sudo device search path:
391 # Path devsearch /dev/path1:/dev/path2:/dev
392 #
393 # A colon-separated list of paths to check when searching for a user's
394 # terminal device.
395 #
396 #Path devsearch /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev
397 #
399 # Sudo noexec:
400 # Path noexec /path/to/sudo_noexec.so
401 #
402 # Path to a shared library containing replacements for the execv(),
403 # execve() and fexecve() library functions that just return an error.
404 # This is used to implement the "noexec" functionality on systems that
405 # support LD_PRELOAD or its equivalent.
406 #
407 # The compiled-in value is usually sufficient and should only be changed
408 # if you rename or move the sudo_noexec.so file.
409 #
410 #Path noexec /usr/libexec/sudo/sudo_noexec.so
411 #
413 # Sudo plugin directory:
414 # Path plugin_dir /path/to/plugins
415 #
416 # The default directory to use when searching for plugins that are
417 # specified without a fully qualified path name.
418 #
419 #Path plugin_dir /usr/libexec/sudo
420 #
422 # Sudo developer mode:
423 # Set developer_mode true|false
424 #
425 # Allow loading of plugins that are owned by non-root or are writable
426 # by "group" or "other". Should only be used during plugin development.
427 #Set developer_mode true
428 #
430 # Core dumps:
431 # Set disable_coredump true|false
432 #
433 # By default, sudo disables core dumps while it is executing (they
434 # are re-enabled for the command that is run).
435 # To aid in debugging sudo problems, you may wish to enable core
436 # dumps by setting "disable_coredump" to false.
437 #
438 #Set disable_coredump false
439 #
441 # User groups:
442 # Set group_source static|dynamic|adaptive
443 #
444 # Sudo passes the user's group list to the policy plugin.
445 # If the user is a member of the maximum number of groups (usually 16),
446 # sudo will query the group database directly to be sure to include
447 # the full list of groups.
448 #
449 # On some systems, this can be expensive so the behavior is configurable.
450 # The "group_source" setting has three possible values:
451 # static - use the user's list of groups returned by the kernel.
452 # dynamic - query the group database to find the list of groups.
453 # adaptive - if user is in less than the maximum number of groups.
454 # use the kernel list, else query the group database.
455 #
456 #Set group_source static
457 #
459 # Sudo interface probing:
460 # Set probe_interfaces true|false
461 #
462 # By default, sudo will probe the system's network interfaces and
463 # pass the IP address of each enabled interface to the policy plugin.
464 # On systems with a large number of virtual interfaces this may take
465 # a noticeable amount of time.
466 #
467 #Set probe_interfaces false
468 #
470 # Sudo debug files:
471 # Debug program /path/to/debug_log subsystem@priority[,subsyste@priority]
472 #
473 # Sudo and related programs support logging debug information to a file.
474 # The program is typically sudo, sudoers.so, sudoreplay or visudo.
475 #
476 # Subsystems vary based on the program; "all" matches all subsystems.
477 # Priority may be crit, err, warn, notice, diag, info, trace or debug.
478 # Multiple subsystem@priority may be specified, separated by a comma.
479 #
480 #Debug sudo /var/log/sudo_debug all@debug
481 #Debug sudoers.so /var/log/sudoers_debug all@debug
482
484 sudo_plugin(5), sudoers(5), sudo(8)
485
487 See the HISTORY file in the sudo distribution (https://www.sudo.ws/his‐
488 tory.html) for a brief history of sudo.
489
491 Many people have worked on sudo over the years; this version consists of
492 code written primarily by:
493 Todd C. Miller
495 See the CONTRIBUTORS file in the sudo distribution
497 (https://www.sudo.ws/contributors.html) for an exhaustive list of people
498 who have contributed to sudo.
499
501 If you feel you have found a bug in sudo, please submit a bug report at
502 https://bugzilla.sudo.ws/
503
505 Limited free support is available via the sudo-users mailing list, see
506 https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
507 the archives.
508
510 sudo is provided “AS IS” and any express or implied warranties, includ‐
511 ing, but not limited to, the implied warranties of merchantability and
512 fitness for a particular purpose are disclaimed. See the LICENSE file
513 distributed with sudo or https://www.sudo.ws/license.html for complete
514 details.
515Sudo 1.9.7p2 March 2, 2021 Sudo 1.9.7p2