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 plug‐
9 in-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 struct policy_plugin or struct io_plugin
44 symbol contained in the plugin. The path may be fully qualified or rela‐
45 tive. If not fully qualified, it is relative to the directory specified
46 by the plugin_dir Path setting, which defaults to /usr/libexec/sudo. In
47 other words:
48 Plugin sudoers_policy sudoers.so
50 is equivalent to:
52 Plugin sudoers_policy /usr/libexec/sudo/sudoers.so
54 If the plugin was compiled statically into the sudo binary instead of
56 being installed as a dynamic shared object, the path should be specified
57 without a leading directory, as it does not actually exist in the file
58 system. For example:
59 Plugin sudoers_policy sudoers.so
61 Starting with sudo 1.8.5, any additional parameters after the path are
63 passed as arguments to the plugin's open function. For example, to over‐
64 ride the compile-time default sudoers file mode:
65 Plugin sudoers_policy sudoers.so sudoers_mode=0440
67 See the sudoers(5) manual for a list of supported arguments.
69 The same dynamic shared object may contain multiple plugins, each with a
71 different symbol name. The file must be owned by uid 0 and only writable
72 by its owner. Because of ambiguities that arise from composite policies,
73 only a single policy plugin may be specified. This limitation does not
74 apply to I/O plugins.
75 If no sudo.conf file is present, or if it contains no Plugin lines, the
77 sudoers plugin will be used as the default security policy and for I/O
78 logging (if enabled by the policy). This is equivalent to the following:
79 Plugin sudoers_policy sudoers.so
81 Plugin sudoers_io sudoers.so
82 For more information on the sudo plugin architecture, see the
84 sudo_plugin(5) manual.
85 Path settings
87 A Path line consists of the Path keyword, followed by the name of the
88 path to set and its value. For example:
89 Path noexec /usr/libexec/sudo/sudo_noexec.so
91 Path askpass /usr/X11R6/bin/ssh-askpass
92 If no path name is specified, features relying on the specified setting
94 will be disabled. Disabling Path settings is only supported in sudo ver‐
95 sion 1.8.16 and higher.
96 The following plugin-agnostic paths may be set in the /etc/sudo.conf
98 file:
99 askpass The fully qualified path to a helper program used to read the
101 user's password when no terminal is available. This may be the
102 case when sudo is executed from a graphical (as opposed to
103 text-based) application. The program specified by askpass
104 should display the argument passed to it as the prompt and
105 write the user's password to the standard output. The value of
106 askpass may be overridden by the SUDO_ASKPASS environment vari‐
107 able.
108 devsearch
110 An ordered, colon-separated search path of directories to look
111 in for device nodes. This is used when mapping the process's
112 tty device number to a device name on systems that do not pro‐
113 vide such a mechanism. Sudo will not recurse into sub-directo‐
114 ries. If terminal devices may be located in a sub-directory of
115 /dev, that path must be explicitly listed in devsearch. The
116 default value is
117 /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev
118 This option is ignored on systems that support either the
120 devname() or _ttyname_dev() functions, for example BSD, macOS
121 and Solaris.
122 noexec The fully-qualified path to a shared library containing wrap‐
124 pers for the execl(), execle(), execlp(), exect(), execv(),
125 execve(), execvP(), execvp(), execvpe(), fexecve(), popen(),
126 posix_spawn(), posix_spawnp(), system(), and wordexp() library
127 functions that prevent the execution of further commands. This
128 is used to implement the noexec functionality on systems that
129 support LD_PRELOAD or its equivalent. The default value is
130 /usr/libexec/sudo/sudo_noexec.so.
131 plugin_dir
133 The default directory to use when searching for plugins that
134 are specified without a fully qualified path name. The default
135 value is /usr/libexec/sudo.
136 sesh The fully-qualified path to the sesh binary. This setting is
138 only used when sudo is built with SELinux support. The default
139 value is /usr/libexec/sudo/sesh.
140 Other settings
142 The sudo.conf file also supports the following front end settings:
143 disable_coredump
145 Core dumps of sudo itself are disabled by default to prevent
146 the disclosure of potentially sensitive information. To aid in
147 debugging sudo crashes, you may wish to re-enable core dumps by
148 setting “disable_coredump” to false in sudo.conf as follows:
149 Set disable_coredump false
151 All modern operating systems place restrictions on core dumps
153 from set-user-ID processes like sudo so this option can be
154 enabled without compromising security. To actually get a sudo
155 core file you will likely need to enable core dumps for set-
156 user-ID processes. On BSD and Linux systems this is accom‐
157 plished in the sysctl(8) command. On Solaris, the coreadm(1m)
158 command is used to configure core dump behavior.
159 This setting is only available in sudo version 1.8.4 and
161 higher.
162 developer_mode
164 By default sudo refuses to load plugins which can be modified
165 by other than the root user. The plugin should be owned by
166 root and write access permissions should be disabled for
167 “group” and “other”. To make development of a plugin easier,
168 you can disable that by setting “developer_mode” option to true
169 in sudo.conf as follows:
170 Set developer_mode true
172 Please note that this creates a security risk, so it is not
174 recommended on critical systems such as a desktop machine for
175 daily use, but is intended to be used in development environ‐
176 ments (VM, container, etc). Before enabling developer mode,
177 ensure you understand the implications.
178 This setting is only available in sudo version 1.9.0 and
180 higher.
181 group_source
183 sudo passes the invoking user's group list to the policy and
184 I/O plugins. On most systems, there is an upper limit to the
185 number of groups that a user may belong to simultaneously (typ‐
186 ically 16 for compatibility with NFS). On systems with the
187 getconf(1) utility, running:
188 getconf NGROUPS_MAX
189 will return the maximum number of groups.
190 However, it is still possible to be a member of a larger number
192 of groups--they simply won't be included in the group list
193 returned by the kernel for the user. Starting with sudo ver‐
194 sion 1.8.7, if the user's kernel group list has the maximum
195 number of entries, sudo will consult the group database
196 directly to determine the group list. This makes it possible
197 for the security policy to perform matching by group name even
198 when the user is a member of more than the maximum number of
199 groups.
200 The group_source setting allows the administrator to change
202 this default behavior. Supported values for group_source are:
203 static Use the static group list that the kernel returns.
205 Retrieving the group list this way is very fast but
206 it is subject to an upper limit as described above.
207 It is “static” in that it does not reflect changes to
208 the group database made after the user logs in. This
209 was the default behavior prior to sudo 1.8.7.
210 dynamic Always query the group database directly. It is
212 “dynamic” in that changes made to the group database
213 after the user logs in will be reflected in the group
214 list. On some systems, querying the group database
215 for all of a user's groups can be time consuming when
216 querying a network-based group database. Most oper‐
217 ating systems provide an efficient method of perform‐
218 ing such queries. Currently, sudo supports efficient
219 group queries on AIX, BSD, HP-UX, Linux and Solaris.
220 adaptive Only query the group database if the static group
222 list returned by the kernel has the maximum number of
223 entries. This is the default behavior in sudo 1.8.7
224 and higher.
225 For example, to cause sudo to only use the kernel's static list
227 of groups for the user:
228 Set group_source static
230 This setting is only available in sudo version 1.8.7 and
232 higher.
233 max_groups
235 The maximum number of user groups to retrieve from the group
236 database. Values less than one will be ignored. This setting
237 is only used when querying the group database directly. It is
238 intended to be used on systems where it is not possible to
239 detect when the array to be populated with group entries is not
240 sufficiently large. By default, sudo will allocate four times
241 the system's maximum number of groups (see above) and retry
242 with double that number if the group database query fails.
243 This setting is only available in sudo version 1.8.7 and
245 higher. It should not be required in sudo versions 1.8.24 and
246 higher and may be removed in a later release.
247 probe_interfaces
249 By default, sudo will probe the system's network interfaces and
250 pass the IP address of each enabled interface to the policy
251 plugin. This makes it possible for the plugin to match rules
252 based on the IP address without having to query DNS. On Linux
253 systems with a large number of virtual interfaces, this may
254 take a non-negligible amount of time. If IP-based matching is
255 not required, network interface probing can be disabled as fol‐
256 lows:
257 Set probe_interfaces false
259 This setting is only available in sudo version 1.8.10 and
261 higher.
262 Debug flags
264 sudo versions 1.8.4 and higher support a flexible debugging framework
265 that can help track down what sudo is doing internally if there is a
266 problem.
267 A Debug line consists of the Debug keyword, followed by the name of the
269 program (or plugin) to debug (sudo, visudo, sudoreplay, sudoers), the
270 debug file name and a comma-separated list of debug flags. The debug
271 flag syntax used by sudo and the sudoers plugin is subsystem@priority but
272 a plugin is free to use a different format so long as it does not include
273 a comma (‘,’).
274 For example:
276 Debug sudo /var/log/sudo_debug all@warn,plugin@info
278 would log all debugging statements at the warn level and higher in addi‐
280 tion to those at the info level for the plugin subsystem.
281 As of sudo 1.8.12, multiple Debug entries may be specified per program.
283 Older versions of sudo only support a single Debug entry per program.
284 Plugin-specific Debug entries are also supported starting with sudo
285 1.8.12 and are matched by either the base name of the plugin that was
286 loaded (for example sudoers.so) or by the plugin's fully-qualified path
287 name. Previously, the sudoers plugin shared the same Debug entry as the
288 sudo front end and could not be configured separately.
289 The following priorities are supported, in order of decreasing severity:
291 crit, err, warn, notice, diag, info, trace and debug. Each priority,
292 when specified, also includes all priorities higher than it. For exam‐
293 ple, a priority of notice would include debug messages logged at notice
294 and higher.
295 The priorities trace and debug also include function call tracing which
297 logs when a function is entered and when it returns. For example, the
298 following trace is for the get_user_groups() function located in
299 src/sudo.c:
300 sudo[123] -> get_user_groups @ src/sudo.c:385
302 sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5
303 When the function is entered, indicated by a right arrow ‘->’, the pro‐
305 gram, process ID, function, source file and line number are logged. When
306 the function returns, indicated by a left arrow ‘<-’, the same informa‐
307 tion is logged along with the return value. In this case, the return
308 value is a string.
309 The following subsystems are used by the sudo front-end:
311 all matches every subsystem
313 args command line argument processing
315 conv user conversation
317 edit sudoedit
319 event event subsystem
321 exec command execution
323 main sudo main function
325 netif network interface handling
327 pcomm communication with the plugin
329 plugin plugin configuration
331 pty pseudo-terminal related code
333 selinux SELinux-specific handling
335 util utility functions
337 utmp utmp handling
339 The sudoers(5) plugin includes support for additional subsystems.
341
343 /etc/sudo.conf sudo front end configuration
344
346 #
347 # Default /etc/sudo.conf file
348 #
349 # Sudo plugins:
350 # Plugin plugin_name plugin_path plugin_options ...
351 #
352 # The plugin_path is relative to /usr/libexec/sudo unless
353 # fully qualified.
354 # The plugin_name corresponds to a global symbol in the plugin
355 # that contains the plugin interface structure.
356 # The plugin_options are optional.
357 #
358 # The sudoers plugin is used by default if no Plugin lines are present.
359 Plugin sudoers_policy sudoers.so
360 Plugin sudoers_io sudoers.so
361 #
363 # Sudo askpass:
364 # Path askpass /path/to/askpass
365 #
366 # An askpass helper program may be specified to provide a graphical
367 # password prompt for "sudo -A" support. Sudo does not ship with its
368 # own askpass program but can use the OpenSSH askpass.
369 #
370 # Use the OpenSSH askpass
371 #Path askpass /usr/X11R6/bin/ssh-askpass
372 #
373 # Use the Gnome OpenSSH askpass
374 #Path askpass /usr/libexec/openssh/gnome-ssh-askpass
375 #
377 # Sudo device search path:
378 # Path devsearch /dev/path1:/dev/path2:/dev
379 #
380 # A colon-separated list of paths to check when searching for a user's
381 # terminal device.
382 #
383 #Path devsearch /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev
384 #
386 # Sudo noexec:
387 # Path noexec /path/to/sudo_noexec.so
388 #
389 # Path to a shared library containing dummy versions of the execv(),
390 # execve() and fexecve() library functions that just return an error.
391 # This is used to implement the "noexec" functionality on systems that
392 # support LD_PRELOAD or its equivalent.
393 #
394 # The compiled-in value is usually sufficient and should only be changed
395 # if you rename or move the sudo_noexec.so file.
396 #
397 #Path noexec /usr/libexec/sudo/sudo_noexec.so
398 #
400 # Sudo plugin directory:
401 # Path plugin_dir /path/to/plugins
402 #
403 # The default directory to use when searching for plugins that are
404 # specified without a fully qualified path name.
405 #
406 #Path plugin_dir /usr/libexec/sudo
407 #
409 # Sudo developer mode:
410 # Set developer_mode true|false
411 #
412 # Allow loading of plugins that are owned by non-root or are writable
413 # by "group" or "other". Should only be used during plugin development.
414 #Set developer_mode true
415 #
417 # Core dumps:
418 # Set disable_coredump true|false
419 #
420 # By default, sudo disables core dumps while it is executing (they
421 # are re-enabled for the command that is run).
422 # To aid in debugging sudo problems, you may wish to enable core
423 # dumps by setting "disable_coredump" to false.
424 #
425 #Set disable_coredump false
426 #
428 # User groups:
429 # Set group_source static|dynamic|adaptive
430 #
431 # Sudo passes the user's group list to the policy plugin.
432 # If the user is a member of the maximum number of groups (usually 16),
433 # sudo will query the group database directly to be sure to include
434 # the full list of groups.
435 #
436 # On some systems, this can be expensive so the behavior is configurable.
437 # The "group_source" setting has three possible values:
438 # static - use the user's list of groups returned by the kernel.
439 # dynamic - query the group database to find the list of groups.
440 # adaptive - if user is in less than the maximum number of groups.
441 # use the kernel list, else query the group database.
442 #
443 #Set group_source static
444 #
446 # Sudo interface probing:
447 # Set probe_interfaces true|false
448 #
449 # By default, sudo will probe the system's network interfaces and
450 # pass the IP address of each enabled interface to the policy plugin.
451 # On systems with a large number of virtual interfaces this may take
452 # a noticeable amount of time.
453 #
454 #Set probe_interfaces false
455 #
457 # Sudo debug files:
458 # Debug program /path/to/debug_log subsystem@priority[,subsyste@priority]
459 #
460 # Sudo and related programs support logging debug information to a file.
461 # The program is typically sudo, sudoers.so, sudoreplay or visudo.
462 #
463 # Subsystems vary based on the program; "all" matches all subsystems.
464 # Priority may be crit, err, warn, notice, diag, info, trace or debug.
465 # Multiple subsystem@priority may be specified, separated by a comma.
466 #
467 #Debug sudo /var/log/sudo_debug all@debug
468 #Debug sudoers.so /var/log/sudoers_debug all@debug
469
471 sudo_plugin(5), sudoers(5), sudo(8)
472
474 See the HISTORY file in the sudo distribution (https://www.sudo.ws/his‐
475 tory.html) for a brief history of sudo.
476
478 Many people have worked on sudo over the years; this version consists of
479 code written primarily by:
480 Todd C. Miller
482 See the CONTRIBUTORS file in the sudo distribution
484 (https://www.sudo.ws/contributors.html) for an exhaustive list of people
485 who have contributed to sudo.
486
488 If you feel you have found a bug in sudo, please submit a bug report at
489 https://bugzilla.sudo.ws/
490
492 Limited free support is available via the sudo-users mailing list, see
493 https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
494 the archives.
495
497 sudo is provided “AS IS” and any express or implied warranties, includ‐
498 ing, but not limited to, the implied warranties of merchantability and
499 fitness for a particular purpose are disclaimed. See the LICENSE file
500 distributed with sudo or https://www.sudo.ws/license.html for complete
501 details.
502Sudo 1.9.0b4 October 20, 2019 Sudo 1.9.0b4