1SUDO.CONF(5)                BSD File Formats Manual               SUDO.CONF(5)
2

NAME

4     sudo.conf — configuration for sudo front end
5

DESCRIPTION

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
11     The sudo.conf file supports the following directives, described in detail
12     below.
13
14     Plugin    a security policy or I/O logging plugin
15
16     Path      a plugin-agnostic path
17
18     Set       a front end setting, such as disable_coredump or group_source
19
20     Debug     debug flags to aid in debugging sudo, sudoreplay, visudo, and
21               the sudoers plugin.
22
23     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
26     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
30     Non-comment lines that don't begin with Plugin, Path, Debug, or Set are
31     silently ignored.
32
33     The sudo.conf file is always parsed in the “C” locale.
34
35   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
41     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
49           Plugin sudoers_policy sudoers.so
50
51     is equivalent to:
52
53           Plugin sudoers_policy /usr/libexec/sudo/sudoers.so
54
55     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
60           Plugin sudoers_policy sudoers.so
61
62     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
66           Plugin sudoers_policy sudoers.so sudoers_mode=0440
67
68     See the sudoers(5) manual for a list of supported arguments.
69
70     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
76     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
80           Plugin sudoers_policy sudoers.so
81           Plugin sudoers_io sudoers.so
82
83     For more information on the sudo plugin architecture, see the
84     sudo_plugin(5) manual.
85
86   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
90           Path noexec /usr/libexec/sudo/sudo_noexec.so
91           Path askpass /usr/X11R6/bin/ssh-askpass
92
93     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
97     The following plugin-agnostic paths may be set in the /etc/sudo.conf
98     file:
99
100     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
109     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
119               This option is ignored on systems that support either the
120               devname() or _ttyname_dev() functions, for example BSD, macOS
121               and Solaris.
122
123     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
132     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
137     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
141   Other settings
142     The sudo.conf file also supports the following front end settings:
143
144     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
150                     Set disable_coredump false
151
152               All modern operating systems place restrictions on core dumps
153               from setuid processes like sudo so this option can be enabled
154               without compromising security.  To actually get a sudo core
155               file you will likely need to enable core dumps for setuid pro‐
156               cesses.  On BSD and Linux systems this is accomplished in the
157               sysctl(8) command.  On Solaris, the coreadm(1m) command is used
158               to configure core dump behavior.
159
160               This setting is only available in sudo version 1.8.4 and
161               higher.
162
163     group_source
164               sudo passes the invoking user's group list to the policy and
165               I/O plugins.  On most systems, there is an upper limit to the
166               number of groups that a user may belong to simultaneously (typ‐
167               ically 16 for compatibility with NFS).  On systems with the
168               getconf(1) utility, running:
169                     getconf NGROUPS_MAX
170               will return the maximum number of groups.
171
172               However, it is still possible to be a member of a larger number
173               of groups--they simply won't be included in the group list
174               returned by the kernel for the user.  Starting with sudo ver‐
175               sion 1.8.7, if the user's kernel group list has the maximum
176               number of entries, sudo will consult the group database
177               directly to determine the group list.  This makes it possible
178               for the security policy to perform matching by group name even
179               when the user is a member of more than the maximum number of
180               groups.
181
182               The group_source setting allows the administrator to change
183               this default behavior.  Supported values for group_source are:
184
185               static    Use the static group list that the kernel returns.
186                         Retrieving the group list this way is very fast but
187                         it is subject to an upper limit as described above.
188                         It is “static” in that it does not reflect changes to
189                         the group database made after the user logs in.  This
190                         was the default behavior prior to sudo 1.8.7.
191
192               dynamic   Always query the group database directly.  It is
193                         “dynamic” in that changes made to the group database
194                         after the user logs in will be reflected in the group
195                         list.  On some systems, querying the group database
196                         for all of a user's groups can be time consuming when
197                         querying a network-based group database.  Most oper‐
198                         ating systems provide an efficient method of perform‐
199                         ing such queries.  Currently, sudo supports efficient
200                         group queries on AIX, BSD, HP-UX, Linux and Solaris.
201
202               adaptive  Only query the group database if the static group
203                         list returned by the kernel has the maximum number of
204                         entries.  This is the default behavior in sudo 1.8.7
205                         and higher.
206
207               For example, to cause sudo to only use the kernel's static list
208               of groups for the user:
209
210                     Set group_source static
211
212               This setting is only available in sudo version 1.8.7 and
213               higher.
214
215     max_groups
216               The maximum number of user groups to retrieve from the group
217               database.  Values less than one will be ignored.  This setting
218               is only used when querying the group database directly.  It is
219               intended to be used on systems where it is not possible to
220               detect when the array to be populated with group entries is not
221               sufficiently large.  By default, sudo will allocate four times
222               the system's maximum number of groups (see above) and retry
223               with double that number if the group database query fails.
224
225               This setting is only available in sudo version 1.8.7 and
226               higher.  It should not be required in sudo versions 1.8.24 and
227               higher and may be removed in a later release.
228
229     probe_interfaces
230               By default, sudo will probe the system's network interfaces and
231               pass the IP address of each enabled interface to the policy
232               plugin.  This makes it possible for the plugin to match rules
233               based on the IP address without having to query DNS.  On Linux
234               systems with a large number of virtual interfaces, this may
235               take a non-negligible amount of time.  If IP-based matching is
236               not required, network interface probing can be disabled as fol‐
237               lows:
238
239                     Set probe_interfaces false
240
241               This setting is only available in sudo version 1.8.10 and
242               higher.
243
244   Debug flags
245     sudo versions 1.8.4 and higher support a flexible debugging framework
246     that can help track down what sudo is doing internally if there is a
247     problem.
248
249     A Debug line consists of the Debug keyword, followed by the name of the
250     program (or plugin) to debug (sudo, visudo, sudoreplay, sudoers), the
251     debug file name and a comma-separated list of debug flags.  The debug
252     flag syntax used by sudo and the sudoers plugin is subsystem@priority but
253     a plugin is free to use a different format so long as it does not include
254     a comma (‘,’).
255
256     For example:
257
258           Debug sudo /var/log/sudo_debug all@warn,plugin@info
259
260     would log all debugging statements at the warn level and higher in addi‐
261     tion to those at the info level for the plugin subsystem.
262
263     As of sudo 1.8.12, multiple Debug entries may be specified per program.
264     Older versions of sudo only support a single Debug entry per program.
265     Plugin-specific Debug entries are also supported starting with sudo
266     1.8.12 and are matched by either the base name of the plugin that was
267     loaded (for example sudoers.so) or by the plugin's fully-qualified path
268     name.  Previously, the sudoers plugin shared the same Debug entry as the
269     sudo front end and could not be configured separately.
270
271     The following priorities are supported, in order of decreasing severity:
272     crit, err, warn, notice, diag, info, trace and debug.  Each priority,
273     when specified, also includes all priorities higher than it.  For exam‐
274     ple, a priority of notice would include debug messages logged at notice
275     and higher.
276
277     The priorities trace and debug also include function call tracing which
278     logs when a function is entered and when it returns.  For example, the
279     following trace is for the get_user_groups() function located in
280     src/sudo.c:
281
282           sudo[123] -> get_user_groups @ src/sudo.c:385
283           sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5
284
285     When the function is entered, indicated by a right arrow ‘->’, the pro‐
286     gram, process ID, function, source file and line number are logged.  When
287     the function returns, indicated by a left arrow ‘<-’, the same informa‐
288     tion is logged along with the return value.  In this case, the return
289     value is a string.
290
291     The following subsystems are used by the sudo front-end:
292
293     all         matches every subsystem
294
295     args        command line argument processing
296
297     conv        user conversation
298
299     edit        sudoedit
300
301     event       event subsystem
302
303     exec        command execution
304
305     main        sudo main function
306
307     netif       network interface handling
308
309     pcomm       communication with the plugin
310
311     plugin      plugin configuration
312
313     pty         pseudo-tty related code
314
315     selinux     SELinux-specific handling
316
317     util        utility functions
318
319     utmp        utmp handling
320
321     The sudoers(5) plugin includes support for additional subsystems.
322

FILES

324     /etc/sudo.conf            sudo front end configuration
325

EXAMPLES

327     #
328     # Default /etc/sudo.conf file
329     #
330     # Format:
331     #   Plugin plugin_name plugin_path plugin_options ...
332     #   Path askpass /path/to/askpass
333     #   Path noexec /path/to/sudo_noexec.so
334     #   Debug sudo /var/log/sudo_debug all@warn
335     #   Set disable_coredump true
336     #
337     # The plugin_path is relative to /usr/libexec/sudo unless
338     #   fully qualified.
339     # The plugin_name corresponds to a global symbol in the plugin
340     #   that contains the plugin interface structure.
341     # The plugin_options are optional.
342     #
343     # The sudoers plugin is used by default if no Plugin lines are
344     # present.
345     Plugin sudoers_policy sudoers.so
346     Plugin sudoers_io sudoers.so
347
348     #
349     # Sudo askpass:
350     #
351     # An askpass helper program may be specified to provide a graphical
352     # password prompt for "sudo -A" support.  Sudo does not ship with
353     # its own askpass program but can use the OpenSSH askpass.
354     #
355     # Use the OpenSSH askpass
356     #Path askpass /usr/X11R6/bin/ssh-askpass
357     #
358     # Use the Gnome OpenSSH askpass
359     #Path askpass /usr/libexec/openssh/gnome-ssh-askpass
360
361     #
362     # Sudo noexec:
363     #
364     # Path to a shared library containing dummy versions of the execv(),
365     # execve() and fexecve() library functions that just return an error.
366     # This is used to implement the "noexec" functionality on systems that
367     # support C<LD_PRELOAD> or its equivalent.
368     # The compiled-in value is usually sufficient and should only be
369     # changed if you rename or move the sudo_noexec.so file.
370     #
371     #Path noexec /usr/libexec/sudo/sudo_noexec.so
372
373     #
374     # Core dumps:
375     #
376     # By default, sudo disables core dumps while it is executing
377     # (they are re-enabled for the command that is run).
378     # To aid in debugging sudo problems, you may wish to enable core
379     # dumps by setting "disable_coredump" to false.
380     #
381     #Set disable_coredump false
382
383     #
384     # User groups:
385     #
386     # Sudo passes the user's group list to the policy plugin.
387     # If the user is a member of the maximum number of groups (usually 16),
388     # sudo will query the group database directly to be sure to include
389     # the full list of groups.
390     #
391     # On some systems, this can be expensive so the behavior is configurable.
392     # The "group_source" setting has three possible values:
393     #   static   - use the user's list of groups returned by the kernel.
394     #   dynamic  - query the group database to find the list of groups.
395     #   adaptive - if user is in less than the maximum number of groups.
396     #              use the kernel list, else query the group database.
397     #
398     #Set group_source static
399

SEE ALSO

401     sudo_plugin(5), sudoers(5), sudo(8)
402

HISTORY

404     See the HISTORY file in the sudo distribution (https://www.sudo.ws/his
405     tory.html) for a brief history of sudo.
406

AUTHORS

408     Many people have worked on sudo over the years; this version consists of
409     code written primarily by:
410
411           Todd C. Miller
412
413     See the CONTRIBUTORS file in the sudo distribution
414     (https://www.sudo.ws/contributors.html) for an exhaustive list of people
415     who have contributed to sudo.
416

BUGS

418     If you feel you have found a bug in sudo, please submit a bug report at
419     https://bugzilla.sudo.ws/
420

SUPPORT

422     Limited free support is available via the sudo-users mailing list, see
423     https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
424     the archives.
425

DISCLAIMER

427     sudo is provided “AS IS” and any express or implied warranties, includ‐
428     ing, but not limited to, the implied warranties of merchantability and
429     fitness for a particular purpose are disclaimed.  See the LICENSE file
430     distributed with sudo or https://www.sudo.ws/license.html for complete
431     details.
432
433Sudo 1.8.25p1                    June 16, 2018                   Sudo 1.8.25p1
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