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

NAME
     sudo.conf -- configuration for sudo front end

DESCRIPTION
     The sudo.conf file is used to configure the sudo front end.  It specifies
     the security policy and I/O logging plugins, debug flags as well as plug-
     in-agnostic path names and settings.

     The sudo.conf file supports the following directives, described in detail
     below.

     Plugin    a security policy or I/O logging plugin

     Path      a plugin-agnostic path

     Set       a front end setting, such as disable_coredump or group_source

     Debug     debug flags to aid in debugging sudo, sudoreplay, visudo, and
	       the sudoers plugin.

     The pound sign (`#') is used to indicate a comment.  Both the comment
     character and any text after it, up to the end of the line, are ignored.

     Long lines can be continued with a backslash (`\') as the last character
     on the line.  Note that leading white space is removed from the beginning
     of lines even when the continuation character is used.

     Non-comment lines that don't begin with Plugin, Path, Debug, or Set are
     silently ignored.

     The sudo.conf file is always parsed in the ``C'' locale.

   Plugin configuration
     sudo supports a plugin architecture for security policies and input/out-
     put logging.  Third parties can develop and distribute their own policy
     and I/O logging plugins to work seamlessly with the sudo front end.
     Plugins are dynamically loaded based on the contents of sudo.conf.

     A Plugin line consists of the Plugin keyword, followed by the symbol_name
     and the path to the dynamic shared object that contains the plugin.  The
     symbol_name is the name of the struct policy_plugin or struct io_plugin
     symbol contained in the plugin.  The path may be fully qualified or rela-
     tive.  If not fully qualified, it is relative to the directory specified
     by the plugin_dir Path setting, which defaults to /usr/libexec/sudo.  In
     other words:

	   Plugin sudoers_policy sudoers.so

     is equivalent to:

	   Plugin sudoers_policy /usr/libexec/sudo/sudoers.so

     If the plugin was compiled statically into the sudo binary instead of
     being installed as a dynamic shared object, the path should be specified
     without a leading directory, as it does not actually exist in the file
     system.  For example:

	   Plugin sudoers_policy sudoers.so

     Starting with sudo 1.8.5, any additional parameters after the path are
     passed as arguments to the plugin's open function.	 For example, to over-
     ride the compile-time default sudoers file mode:

	   Plugin sudoers_policy sudoers.so sudoers_mode=0440

     See the sudoers(5) manual for a list of supported arguments.

     The same dynamic shared object may contain multiple plugins, each with a
     different symbol name.  The file must be owned by uid 0 and only writable
     by its owner.  Because of ambiguities that arise from composite policies,
     only a single policy plugin may be specified.  This limitation does not
     apply to I/O plugins.

     If no sudo.conf file is present, or if it contains no Plugin lines, the
     sudoers plugin will be used as the default security policy and for I/O
     logging (if enabled by the policy).  This is equivalent to the following:

	   Plugin sudoers_policy sudoers.so
	   Plugin sudoers_io sudoers.so

     For more information on the sudo plugin architecture, see the
     sudo_plugin(5) manual.

   Path settings
     A Path line consists of the Path keyword, followed by the name of the
     path to set and its value.	 For example:

	   Path noexec /usr/libexec/sudo/sudo_noexec.so
	   Path askpass /usr/X11R6/bin/ssh-askpass

     If no path name is specified, features relying on the specified setting
     will be disabled.	Disabling Path settings is only supported in sudo ver-
     sion 1.8.16 and higher.

     The following plugin-agnostic paths may be set in the /etc/sudo.conf
     file:

     askpass   The fully qualified path to a helper program used to read the
	       user's password when no terminal is available.  This may be the
	       case when sudo is executed from a graphical (as opposed to
	       text-based) application.	 The program specified by askpass
	       should display the argument passed to it as the prompt and
	       write the user's password to the standard output.  The value of
	       askpass may be overridden by the SUDO_ASKPASS environment vari-
	       able.

     devsearch
	       An ordered, colon-separated search path of directories to look
	       in for device nodes.  This is used when mapping the process's
	       tty device number to a device name on systems that do not pro-
	       vide such a mechanism.  Sudo will not recurse into sub-directo-
	       ries.  If terminal devices may be located in a sub-directory of
	       /dev, that path must be explicitly listed in devsearch.	The
	       default value is:
	       /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev

	       This option is ignored on systems that support either the
	       devname() or _ttyname_dev() functions, for example BSD, macOS
	       and Solaris.

     noexec    The fully-qualified path to a shared library containing wrap-
	       pers for the execl(), execle(), execlp(), exect(), execv(),
	       execve(), execvP(), execvp(), execvpe(), fexecve(), popen(),
	       posix_spawn(), posix_spawnp(), system(), and wordexp() library
	       functions that prevent the execution of further commands.  This
	       is used to implement the noexec functionality on systems that
	       support LD_PRELOAD or its equivalent.  The default value is:
	       /usr/libexec/sudo/sudo_noexec.so.

     plugin_dir
	       The default directory to use when searching for plugins that
	       are specified without a fully qualified path name.  The default
	       value is /usr/libexec/sudo.

     sesh      The fully-qualified path to the sesh binary.  This setting is
	       only used when sudo is built with SELinux support.  The default
	       value is /usr/libexec/sudo/sesh.

   Other settings
     The sudo.conf file also supports the following front end settings:

     disable_coredump
	       Core dumps of sudo itself are disabled by default to prevent
	       the disclosure of potentially sensitive information.  To aid in
	       debugging sudo crashes, you may wish to re-enable core dumps by
	       setting ``disable_coredump'' to false in sudo.conf as follows:

		     Set disable_coredump false

	       All modern operating systems place restrictions on core dumps
	       from setuid processes like sudo so this option can be enabled
	       without compromising security.  To actually get a sudo core
	       file you will likely need to enable core dumps for setuid pro-
	       cesses.	On BSD and Linux systems this is accomplished in the
	       sysctl command.	On Solaris, the coreadm command is used to
	       configure core dump behavior.

	       This setting is only available in sudo version 1.8.4 and
	       higher.

     group_source
	       sudo passes the invoking user's group list to the policy and
	       I/O plugins.  On most systems, there is an upper limit to the
	       number of groups that a user may belong to simultaneously (typ-
	       ically 16 for compatibility with NFS).  On systems with the
	       getconf(1) utility, running:
		     getconf NGROUPS_MAX
	       will return the maximum number of groups.

	       However, it is still possible to be a member of a larger number
	       of groups--they simply won't be included in the group list
	       returned by the kernel for the user.  Starting with sudo ver-
	       sion 1.8.7, if the user's kernel group list has the maximum
	       number of entries, sudo will consult the group database
	       directly to determine the group list.  This makes it possible
	       for the security policy to perform matching by group name even
	       when the user is a member of more than the maximum number of
	       groups.

	       The group_source setting allows the administrator to change
	       this default behavior.  Supported values for group_source are:

	       static	 Use the static group list that the kernel returns.
			 Retrieving the group list this way is very fast but
			 it is subject to an upper limit as described above.
			 It is ``static'' in that it does not reflect changes
			 to the group database made after the user logs in.
			 This was the default behavior prior to sudo 1.8.7.

	       dynamic	 Always query the group database directly.  It is
			 ``dynamic'' in that changes made to the group data-
			 base after the user logs in will be reflected in the
			 group list.  On some systems, querying the group
			 database for all of a user's groups can be time con-
			 suming when querying a network-based group database.
			 Most operating systems provide an efficient method of
			 performing such queries.  Currently, sudo supports
			 efficient group queries on AIX, BSD, HP-UX, Linux and
			 Solaris.

	       adaptive	 Only query the group database if the static group
			 list returned by the kernel has the maximum number of
			 entries.  This is the default behavior in sudo 1.8.7
			 and higher.

	       For example, to cause sudo to only use the kernel's static list
	       of groups for the user:

		     Set group_source static

	       This setting is only available in sudo version 1.8.7 and
	       higher.

     max_groups
	       The maximum number of user groups to retrieve from the group
	       database.  Values less than one will be ignored.	 This setting
	       is only used when querying the group database directly.	It is
	       intended to be used on systems where it is not possible to
	       detect when the array to be populated with group entries is not
	       sufficiently large.  By default, sudo will allocate four times
	       the system's maximum number of groups (see above) and retry
	       with double that number if the group database query fails.
	       However, some systems just return as many entries as will fit
	       and do not indicate an error when there is a lack of space.

	       This setting is only available in sudo version 1.8.7 and
	       higher.

     probe_interfaces
	       By default, sudo will probe the system's network interfaces and
	       pass the IP address of each enabled interface to the policy
	       plugin.	This makes it possible for the plugin to match rules
	       based on the IP address without having to query DNS.  On Linux
	       systems with a large number of virtual interfaces, this may
	       take a non-negligible amount of time.  If IP-based matching is
	       not required, network interface probing can be disabled as fol-
	       lows:

		     Set probe_interfaces false

	       This setting is only available in sudo version 1.8.10 and
	       higher.

   Debug flags
     sudo versions 1.8.4 and higher support a flexible debugging framework
     that can help track down what sudo is doing internally if there is a
     problem.

     A Debug line consists of the Debug keyword, followed by the name of the
     program (or plugin) to debug (sudo, visudo, sudoreplay, sudoers), the
     debug file name and a comma-separated list of debug flags.	 The debug
     flag syntax used by sudo and the sudoers plugin is subsystem@priority but
     a plugin is free to use a different format so long as it does not include
     a comma (`,').

     For example:

	   Debug sudo /var/log/sudo_debug all@warn,plugin@info

     would log all debugging statements at the warn level and higher in addi-
     tion to those at the info level for the plugin subsystem.

     As of sudo 1.8.12, multiple Debug entries may be specified per program.
     Older versions of sudo only support a single Debug entry per program.
     Plugin-specific Debug entries are also supported starting with sudo
     1.8.12 and are matched by either the base name of the plugin that was
     loaded (for example sudoers.so) or by the plugin's fully-qualified path
     name.  Previously, the sudoers plugin shared the same Debug entry as the
     sudo front end and could not be configured separately.

     The following priorities are supported, in order of decreasing severity:
     crit, err, warn, notice, diag, info, trace and debug.  Each priority,
     when specified, also includes all priorities higher than it.  For exam-
     ple, a priority of notice would include debug messages logged at notice
     and higher.

     The priorities trace and debug also include function call tracing which
     logs when a function is entered and when it returns.  For example, the
     following trace is for the get_user_groups() function located in
     src/sudo.c:

	   sudo[123] -> get_user_groups @ src/sudo.c:385
	   sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5

     When the function is entered, indicated by a right arrow `->', the pro-
     gram, process ID, function, source file and line number are logged.  When
     the function returns, indicated by a left arrow `<-', the same informa-
     tion is logged along with the return value.  In this case, the return
     value is a string.

     The following subsystems are used by the sudo front-end:

     all	 matches every subsystem

     args	 command line argument processing

     conv	 user conversation

     edit	 sudoedit

     event	 event subsystem

     exec	 command execution

     main	 sudo main function

     netif	 network interface handling

     pcomm	 communication with the plugin

     plugin	 plugin configuration

     pty	 pseudo-tty related code

     selinux	 SELinux-specific handling

     util	 utility functions

     utmp	 utmp handling

     The sudoers(5) plugin includes support for additional subsystems.

FILES
     /etc/sudo.conf	       sudo front end configuration

EXAMPLES
     #
     # Default /etc/sudo.conf file
     #
     # Format:
     #	 Plugin plugin_name plugin_path plugin_options ...
     #	 Path askpass /path/to/askpass
     #	 Path noexec /path/to/sudo_noexec.so
     #	 Debug sudo /var/log/sudo_debug all@warn
     #	 Set disable_coredump true
     #
     # The plugin_path is relative to /usr/libexec/sudo unless
     #	 fully qualified.
     # The plugin_name corresponds to a global symbol in the plugin
     #	 that contains the plugin interface structure.
     # The plugin_options are optional.
     #
     # The sudoers plugin is used by default if no Plugin lines are
     # present.
     Plugin sudoers_policy sudoers.so
     Plugin sudoers_io sudoers.so

     #
     # Sudo askpass:
     #
     # An askpass helper program may be specified to provide a graphical
     # password prompt for "sudo -A" support.  Sudo does not ship with
     # its own askpass program but can use the OpenSSH askpass.
     #
     # Use the OpenSSH askpass
     #Path askpass /usr/X11R6/bin/ssh-askpass
     #
     # Use the Gnome OpenSSH askpass
     #Path askpass /usr/libexec/openssh/gnome-ssh-askpass

     #
     # Sudo noexec:
     #
     # Path to a shared library containing dummy versions of the execv(),
     # execve() and fexecve() library functions that just return an error.
     # This is used to implement the "noexec" functionality on systems that
     # support C<LD_PRELOAD> or its equivalent.
     # The compiled-in value is usually sufficient and should only be
     # changed if you rename or move the sudo_noexec.so file.
     #
     #Path noexec /usr/libexec/sudo/sudo_noexec.so

     #
     # Core dumps:
     #
     # By default, sudo disables core dumps while it is executing
     # (they are re-enabled for the command that is run).
     # To aid in debugging sudo problems, you may wish to enable core
     # dumps by setting "disable_coredump" to false.
     #
     #Set disable_coredump false

     #
     # User groups:
     #
     # Sudo passes the user's group list to the policy plugin.
     # If the user is a member of the maximum number of groups (usually 16),
     # sudo will query the group database directly to be sure to include
     # the full list of groups.
     #
     # On some systems, this can be expensive so the behavior is configurable.
     # The "group_source" setting has three possible values:
     #	 static	  - use the user's list of groups returned by the kernel.
     #	 dynamic  - query the group database to find the list of groups.
     #	 adaptive - if user is in less than the maximum number of groups.
     #		    use the kernel list, else query the group database.
     #
     #Set group_source static

SEE ALSO
     sudoers(5), sudo(8), sudo_plugin(5)

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

AUTHORS
     Many people have worked on sudo over the years; this version consists of
     code written primarily by:

	   Todd C. Miller

     See the CONTRIBUTORS file in the sudo distribution
     (https://www.sudo.ws/contributors.html) for an exhaustive list of people
     who have contributed to sudo.

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

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

DISCLAIMER
     sudo is provided ``AS IS'' and any express or implied warranties, includ-
     ing, but not limited to, the implied warranties of merchantability and
     fitness for a particular purpose are disclaimed.  See the LICENSE file
     distributed with sudo or https://www.sudo.ws/license.html for complete
     details.

Sudo 1.8.23			 July 21, 2017			   Sudo 1.8.23