sudo.conf(5) — Linux manual page

NAME | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | AUTHORS | BUGS | SUPPORT | DISCLAIMER | COLOPHON

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

NAME         top

       sudo.conf — configuration for sudo front-end

DESCRIPTION         top

       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 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
       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/local/libexec/sudo.  In other words:

           Plugin sudoers_policy sudoers.so

       is equivalent to:

           Plugin sudoers_policy /usr/local/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 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, 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/local/libexec/sudo/sudo_intercept.so
           Path noexec /usr/local/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 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
             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 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
             intercepts 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/local/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/local/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/local/libexec/sudo.

   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
             simultaneously (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 efficient 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.  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 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         top

       /etc/sudo.conf            sudo front-end configuration

EXAMPLES         top

       #
       # Default /etc/sudo.conf file
       #
       # Sudo plugins:
       #   Plugin plugin_name plugin_path plugin_options ...
       #
       # The plugin_path is relative to /usr/local/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/X11R6/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/local/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/local/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/local/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         top

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

AUTHORS         top

       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         top

       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 <[email protected]> (private).

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

SUPPORT         top

       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         top

       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
       disclaimed.  See the LICENSE.md file distributed with sudo or
       https://www.sudo.ws/about/license/ for complete details.

COLOPHON         top

       This page is part of the sudo (execute a command as another user)
       project.  Information about the project can be found at
       https://www.sudo.ws/.  If you have a bug report for this manual
       page, see ⟨https://bugzilla.sudo.ws/⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/sudo-project/sudo⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-08.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       [email protected]

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