sudo.conf

SUDO.CONF(5) 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 is used to configure sudo plugins, plugin-agnostic path names, debug flags, and other settings.

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

   Plugin  an approval, audit, I/O logging, or security policy 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.  Leading white space is removed from the beginning of lines even when a 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/output logging.  Third parties can develop and distribute their own policy and I/O logging plugins to work seam
   lessly 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  approval_plugin,  struct  audit_plugin,  struct io_plugin, or struct policy_plugin defined by the plugin.  If a plugin implements multiple plugin types, there must be a Plugin
   line for each unique symbol name.  The path may be fully qualified or relative.  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

   On AIX systems, the plugin may be either a shared object ending in .so or an archive file containing a shared object ending in .a with the name of the shared object in parentheses
   at the end.

   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 override 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 user-ID 0 and only writable by its owner.  Because of ambi
   guities 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, for I/O logging (if enabled by the policy), and for
   auditing.  This is equivalent to the following:

       Plugin sudoers_policy sudoers.so
       Plugin sudoers_io sudoers.so
       Plugin sudoers_audit sudoers.so

   Starting with sudo version 1.9.1, some of the logging functionality of the sudoers plugin has been moved from the policy plugin to an audit plugin.   To  maintain  compatibility  with
   sudo.conf  files from older sudo versions, if sudoers is configured as the security policy, it will be used as an audit plugin as well.  This guarantees that the logging behavior will
   be consistent with that of sudo versions 1.9.0 and below.

   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 intercept /usr/libexec/sudo/sudo_intercept.so
       Path noexec /usr/libexec/sudo/sudo_noexec.so
       Path askpass /usr/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 version 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 op‐
         posed 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 variable.

   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 provide such a mechanism.  Sudo will not recurse into sub-directories.  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.

   intercept
         The path to a shared library containing a wrappers for the execve(2), execl(3), execle(3), execlp(3), execv(3), execvp(3), execvpe(3), and system(3) library functions  that  in
         tercepts attempts to run further commands and performs a policy check before allowing them to be executed.  This is used to implement the intercept and log_subcmds functionality
         on systems that support LD_PRELOAD or the equivalent.

         The  intercept path may be set to either a single fully-qualified path, or, for systems that support separate LD_PRELOAD environment variables for 32-bit and 64-bit executables,
         it may optionally be set to two fully-qualified paths separated by a colon (:).  The first path should be the 32-bit version and the second the 64-bit version.  This  two-path
         form is currently only supported on AIX and Solaris systems.  The default value is /usr/libexec/sudo/sudo_intercept.so.

   noexec
         The  path  to  a  shared  library  containing  wrappers  for  the  execve(2),  execl(3), execle(3), execlp(3), exect(3), execv(3), execveat(3), execvP(3), execvp(3), execvpe(3),
         fexecve(3), popen(3), posix_spawn(3), posix_spawnp(3), system(3), and wordexp(3) library functions that prevent the execution of further commands.  This is used to implement the
         noexec functionality on systems that support LD_PRELOAD or the equivalent.

         The noexec path may be set to either a single fully-qualified path, or, for systems that support separate LD_PRELOAD environment variables for 32-bit and 64-bit executables,  it
         may  optionally  be  set  to two fully-qualified paths separated by a colon (:).  The first path should be the 32-bit version and the second the 64-bit version.  This two-path
         form is currently only supported on AIX and Solaris systems.  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 set-user-ID 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 set-user-ID processes.  On BSD and Linux systems this is accomplished in the sysctl(8) command.  On  Solaris,  the
         coreadm(1m) 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 simultane‐
         ously (typically 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  version 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 database 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 consuming when querying a network-based group database.  Most operating systems provide an ef
               ficient method of performing such queries.  Currently, sudo supports efficient group queries on AIX, BSD, Linux, macOS, and Solaris.  This is the default behavior on macOS
               in sudo 1.9.6 and higher.

         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 on systems other than  macOS
               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 or larger than 1024 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.

         This setting is only available in sudo version 1.8.7 and higher.  It should not be required in sudo versions 1.8.24 and higher and may be removed in a later release.

   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 follows:

             Set probe_interfaces false

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

Debug settings

   sudo versions 1.8.4 and higher support a flexible debugging framework that can log 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, plugin, or shared object to debug, the debug file name, and a comma-separated list of debug flags.
   The debug flag syntax used by sudo, the sudoers plugin along with its associated programs and shared objects is subsystem@priority but a third-party plugin is free to use a  different
   format so long as it does not include a comma (,).

   On  AIX  systems, a Debug line will match a plugin specified as either the name of an SVR4-style shared object file ending in .so, an archive file ending in .a, or an archive file
   ending in .a with the name of the shared object in parentheses.

   Examples:

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

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

       Debug sudo_intercept.so /var/log/intercept_debug all@debug

   would log all debugging statements, regardless of level, for the sudo_intercept.so shared library that implements sudo's intercept functionality on some systems.

       Debug sudoers.so /var/log/sudoers_debug all@debug

   would log all debugging statements, regardless of level, for the sudoers plugin.  See sudoers(5) for the full list of subsystems supported by the sudoers plugin.

   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.  Pre
   viously, 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  pri
   orities higher than it.  For example, 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 program, process ID, function, source file, and line number are logged.  When the function returns, indicated  by  a
   left arrow <-, the same information 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-terminal 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
   #
   # Sudo plugins:
   #   Plugin plugin_name plugin_path plugin_options ...
   #
   # 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
   #Plugin sudoers_audit sudoers.so

   #
   # Sudo askpass:
   #   Path askpass /path/to/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/bin/ssh-askpass
   #
   # Use the Gnome OpenSSH askpass
   #Path askpass /usr/libexec/openssh/gnome-ssh-askpass

   #
   # Sudo device search path:
   #   Path devsearch /dev/path1:/dev/path2:/dev
   #
   # A colon-separated list of paths to check when searching for a user's
   # terminal device.
   #
   #Path devsearch /dev/pts:/dev/vt:/dev/term:/dev/zcons:/dev/pty:/dev

   #
   # Sudo command interception:
   #   Path intercept /path/to/sudo_intercept.so
   #
   # Path to a shared library containing replacements for the execv()
   # and execve() library functions that perform a policy check to verify
   # the command is allowed and simply return an error if not.  This is
   # used to implement the "intercept" functionality on systems that
   # support LD_PRELOAD or its equivalent.
   #
   # The compiled-in value is usually sufficient and should only be changed
   # if you rename or move the sudo_intercept.so file.
   #
   #Path intercept /usr/libexec/sudo/sudo_intercept.so

   #
   # Sudo noexec:
   #   Path noexec /path/to/sudo_noexec.so
   #
   # Path to a shared library containing replacements for the execv()
   # family of library functions that just return an error.  This is
   # used to implement the "noexec" functionality on systems that support
   # 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

   #
   # Sudo plugin directory:
   #   Path plugin_dir /path/to/plugins
   #
   # The default directory to use when searching for plugins that are
   # specified without a fully qualified path name.
   #
   #Path plugin_dir /usr/libexec/sudo

   #
   # Core dumps:
   #   Set disable_coredump true|false
   #
   # 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:
   #   Set group_source static|dynamic|adaptive
   #
   # 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

   #
   # Sudo interface probing:
   #   Set probe_interfaces true|false
   #
   # By default, sudo will probe the system's network interfaces and
   # pass the IP address of each enabled interface to the policy plugin.
   # On systems with a large number of virtual interfaces this may take
   # a noticeable amount of time.
   #
   #Set probe_interfaces false

   #
   # Sudo debug files:
   #   Debug program /path/to/debug_log subsystem@priority[,subsyste@priority]
   #
   # Sudo and related programs support logging debug information to a file.
   # The program is typically sudo, sudoers.so, sudoreplay, or visudo.
   #
   # Subsystems vary based on the program; "all" matches all subsystems.
   # Priority may be crit, err, warn, notice, diag, info, trace, or debug.
   # Multiple subsystem@priority may be specified, separated by a comma.
   #
   #Debug sudo /var/log/sudo_debug all@debug
   #Debug sudoers.so /var/log/sudoers_debug all@debug

SEE ALSO

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

AUTHORS

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

         Todd C. Miller

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

BUGS

   If  you  believe  you have found a bug in sudo.conf, you can either file a bug report in the sudo bug database, https://bugzilla.sudo.ws/, or open an issue at https://github.com/sudo-
   project/sudo/issues.  If you would prefer to use email, messages  may  be  sent  to  the  sudo-workers  mailing  list,  https://www.sudo.ws/mailman/listinfo/sudo-workers  (public)  or
   <sudo@sudo.ws> (private).

   Please  not  report  security  vulnerabilities through public GitHub issues, Bugzilla or mailing lists.  Instead, report them via email to <Todd.Miller@sudo.ws>.  You may encrypt your
   message with PGP if you would like, using the key found at https://www.sudo.ws/dist/PGPKEYS.

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, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are  dis
   claimed.  See the LICENSE.md file distributed with sudo or https://www.sudo.ws/about/license/ for complete details.

Sudo 1.9.16p2 November 6, 2023 SUDO.CONF(5)