xenial (8) sudo_plugin.8.gz

Provided by: sudo_1.8.16-0ubuntu1.10_amd64 bug

NAME

     sudo_plugin — Sudo Plugin API

DESCRIPTION

     Starting with version 1.8, sudo supports a plugin API for policy and session logging.  Plugins may be
     compiled as dynamic shared objects (the default on systems that support them) or compiled statically into
     the sudo binary itself.  By default, the sudoers policy plugin and an associated I/O logging plugin are
     used.  Via the plugin API, sudo can be configured to use alternate policy and/or I/O logging plugins
     provided by third parties.  The plugins to be used are specified in the sudo.conf(5) file.

     The API is versioned with a major and minor number.  The minor version number is incremented when additions
     are made.  The major number is incremented when incompatible changes are made.  A plugin should be check
     the version passed to it and make sure that the major version matches.

     The plugin API is defined by the sudo_plugin.h header file.

   Policy plugin API
     A policy plugin must declare and populate a policy_plugin struct in the global scope.  This structure
     contains pointers to the functions that implement the sudo policy checks.  The name of the symbol should be
     specified in sudo.conf(5) along with a path to the plugin so that sudo can load it.

     struct policy_plugin {
     #define SUDO_POLICY_PLUGIN     1
         unsigned int type; /* always SUDO_POLICY_PLUGIN */
         unsigned int version; /* always SUDO_API_VERSION */
         int (*open)(unsigned int version, sudo_conv_t conversation,
                     sudo_printf_t plugin_printf, char * const settings[],
                     char * const user_info[], char * const user_env[],
                     char * const plugin_options[]);
         void (*close)(int exit_status, int error);
         int (*show_version)(int verbose);
         int (*check_policy)(int argc, char * const argv[],
                             char *env_add[], char **command_info[],
                             char **argv_out[], char **user_env_out[]);
         int (*list)(int argc, char * const argv[], int verbose,
                     const char *list_user);
         int (*validate)(void);
         void (*invalidate)(int remove);
         int (*init_session)(struct passwd *pwd, char **user_env[]);
         void (*register_hooks)(int version,
            int (*register_hook)(struct sudo_hook *hook));
         void (*deregister_hooks)(int version,
            int (*deregister_hook)(struct sudo_hook *hook));
     };

     The policy_plugin struct has the following fields:

     type  The type field should always be set to SUDO_POLICY_PLUGIN.

     version
           The version field should be set to SUDO_API_VERSION.

           This allows sudo to determine the API version the plugin was built against.

     open
           int (*open)(unsigned int version, sudo_conv_t conversation,
                       sudo_printf_t plugin_printf, char * const settings[],
                       char * const user_info[], char * const user_env[],
                       char * const plugin_options[]);

           Returns 1 on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error.
           In the latter case, sudo will print a usage message before it exits.  If an error occurs, the plugin
           may optionally call the conversation() or plugin_printf() function with SUDO_CONF_ERROR_MSG to
           present additional error information to the user.

           The function arguments are as follows:

           version
                 The version passed in by sudo allows the plugin to determine the major and minor version number
                 of the plugin API supported by sudo.

           conversation
                 A pointer to the conversation() function that can be used by the plugin to interact with the
                 user (see below).  Returns 0 on success and -1 on failure.

           plugin_printf
                 A pointer to a printf()-style function that may be used to display informational or error
                 messages (see below).  Returns the number of characters printed on success and -1 on failure.

           settings
                 A vector of user-supplied sudo settings in the form of “name=value” strings.  The vector is
                 terminated by a NULL pointer.  These settings correspond to flags the user specified when
                 running sudo.  As such, they will only be present when the corresponding flag has been
                 specified on the command line.

                 When parsing settings, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

                 bsdauth_type=string
                       Authentication type, if specified by the -a flag, to use on systems where BSD
                       authentication is supported.

                 closefrom=number
                       If specified, the user has requested via the -C flag that sudo close all files
                       descriptors with a value of number or higher.  The plugin may optionally pass this, or
                       another value, back in the command_info list.

                 debug_flags=string
                       A debug file path name followed by a space and a comma-separated list of debug flags that
                       correspond to the plugin's Debug entry in sudo.conf(5), if there is one.  The flags are
                       passed to the plugin exactly as they appear in sudo.conf(5).  The 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 (‘,’).  Prior to sudo 1.8.12, there was no way to
                       specify plugin-specific debug_flags so the value was always the same as that used by the
                       sudo front end and did not include a path name, only the flags themselves.  As of version
                       1.7 of the plugin interface, sudo will only pass debug_flags if sudo.conf(5) contains a
                       plugin-specific Debug entry.

                 debug_level=number
                       This setting has been deprecated in favor of debug_flags.

                 ignore_ticket=bool
                       Set to true if the user specified the -k flag along with a command, indicating that the
                       user wishes to ignore any cached authentication credentials.  implied_shell to true.
                       This allows sudo with no arguments to be used similarly to su(1).  If the plugin does not
                       to support this usage, it may return a value of -2 from the check_policy() function,
                       which will cause sudo to print a usage message and exit.

                 implied_shell=bool
                       If the user does not specify a program on the command line, sudo will pass the plugin the
                       path to the user's shell and set

                 login_class=string
                       BSD login class to use when setting resource limits and nice value, if specified by the
                       -c flag.

                 login_shell=bool
                       Set to true if the user specified the -i flag, indicating that the user wishes to run a
                       login shell.

                 max_groups=int
                       The maximum number of groups a user may belong to.  This will only be present if there is
                       a corresponding setting in sudo.conf(5).

                 network_addrs=list
                       A space-separated list of IP network addresses and netmasks in the form “addr/netmask”,
                       e.g. “192.168.1.2/255.255.255.0”.  The address and netmask pairs may be either IPv4 or
                       IPv6, depending on what the operating system supports.  If the address contains a colon
                       (‘:’), it is an IPv6 address, else it is IPv4.

                 noninteractive=bool
                       Set to true if the user specified the -n flag, indicating that sudo should operate in
                       non-interactive mode.  The plugin may reject a command run in non-interactive mode if
                       user interaction is required.

                 plugin_dir=string
                       The default plugin directory used by the sudo front end.  This is the default directory
                       set at compile time and may not correspond to the directory the running plugin was loaded
                       from.  It may be used by a plugin to locate support files.

                 plugin_path=string
                       The path name of plugin loaded by the sudo front end.  The path name will be a fully-
                       qualified unless the plugin was statically compiled into sudo.

                 preserve_environment=bool
                       Set to true if the user specified the -E flag, indicating that the user wishes to
                       preserve the environment.

                 preserve_groups=bool
                       Set to true if the user specified the -P flag, indicating that the user wishes to
                       preserve the group vector instead of setting it based on the runas user.

                 progname=string
                       The command name that sudo was run as, typically “sudo” or “sudoedit”.

                 prompt=string
                       The prompt to use when requesting a password, if specified via the -p flag.

                 remote_host=string
                       The name of the remote host to run the command on, if specified via the -h option.
                       Support for running the command on a remote host is meant to be implemented via a helper
                       program that is executed in place of the user-specified command.  The sudo front end is
                       only capable of executing commands on the local host.  Only available starting with API
                       version 1.4.

                 run_shell=bool
                       Set to true if the user specified the -s flag, indicating that the user wishes to run a
                       shell.

                 runas_group=string
                       The group name or gid to run the command as, if specified via the -g flag.

                 runas_user=string
                       The user name or uid to run the command as, if specified via the -u flag.

                 selinux_role=string
                       SELinux role to use when executing the command, if specified by the -r flag.

                 selinux_type=string
                       SELinux type to use when executing the command, if specified by the -t flag.

                 set_home=bool
                       Set to true if the user specified the -H flag.  If true, set the HOME environment
                       variable to the target user's home directory.

                 sudoedit=bool
                       Set to true when the -e flag is is specified or if invoked as sudoedit.  The plugin shall
                       substitute an editor into argv in the check_policy() function or return -2 with a usage
                       error if the plugin does not support sudoedit.  For more information, see the
                       check_policy section.

                 Additional settings may be added in the future so the plugin should silently ignore settings
                 that it does not recognize.

           user_info
                 A vector of information about the user running the command in the form of “name=value” strings.
                 The vector is terminated by a NULL pointer.

                 When parsing user_info, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

                 cols=int
                       The number of columns the user's terminal supports.  If there is no terminal device
                       available, a default value of 80 is used.

                 cwd=string
                       The user's current working directory.

                 egid=gid_t
                       The effective group ID of the user invoking sudo.

                 euid=uid_t
                       The effective user ID of the user invoking sudo.

                 gid=gid_t
                       The real group ID of the user invoking sudo.

                 groups=list
                       The user's supplementary group list formatted as a string of comma-separated group IDs.

                 host=string
                       The local machine's hostname as returned by the gethostname(2) system call.

                 lines=int
                       The number of lines the user's terminal supports.  If there is no terminal device
                       available, a default value of 24 is used.

                 pgid=int
                       The ID of the process group that the running sudo process is a member of.  Only available
                       starting with API version 1.2.

                 pid=int
                       The process ID of the running sudo process.  Only available starting with API version
                       1.2.

                 plugin_options
                       Any (non-comment) strings immediately after the plugin path are passed as arguments to
                       the plugin.  These arguments are split on a white space boundary and are passed to the
                       plugin in the form of a NULL-terminated array of strings.  If no arguments were
                       specified, plugin_options will be the NULL pointer.

                       NOTE: the plugin_options parameter is only available starting with API version 1.2.  A
                       plugin must check the API version specified by the sudo front end before using
                       plugin_options.  Failure to do so may result in a crash.

                 ppid=int
                       The parent process ID of the running sudo process.  Only available starting with API
                       version 1.2.

                 sid=int
                       The session ID of the running sudo process or 0 if sudo is not part of a POSIX job
                       control session.  Only available starting with API version 1.2.

                 tcpgid=int
                       The ID of the foreground process group associated with the terminal device associated
                       with the sudo process or -1 if there is no terminal present.  Only available starting
                       with API version 1.2.

                 tty=string
                       The path to the user's terminal device.  If the user has no terminal device associated
                       with the session, the value will be empty, as in “tty=”.

                 uid=uid_t
                       The real user ID of the user invoking sudo.

                 user=string
                       The name of the user invoking sudo.

           user_env
                 The user's environment in the form of a NULL-terminated vector of “name=value” strings.

                 When parsing user_env, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

     close
           void (*close)(int exit_status, int error);

           The close() function is called when the command being run by sudo finishes.

           The function arguments are as follows:

           exit_status
                 The command's exit status, as returned by the wait(2) system call.  The value of exit_status is
                 undefined if error is non-zero.

           error
                 If the command could not be executed, this is set to the value of errno set by the execve(2)
                 system call.  The plugin is responsible for displaying error information via the conversation()
                 or plugin_printf() function.  If the command was successfully executed, the value of error is
                 0.

           If no close() function is defined, no I/O logging plugins are loaded, and neither the timeout not
           use_pty options are set in the command_info list, the sudo front end may execute the command directly
           instead of running it as a child process.

     show_version
           int (*show_version)(int verbose);

           The show_version() function is called by sudo when the user specifies the -V option.  The plugin may
           display its version information to the user via the conversation() or plugin_printf() function using
           SUDO_CONV_INFO_MSG.  If the user requests detailed version information, the verbose flag will be set.

     check_policy
           int (*check_policy)(int argc, char * const argv[]
                               char *env_add[], char **command_info[],
                               char **argv_out[], char **user_env_out[]);

           The check_policy() function is called by sudo to determine whether the user is allowed to run the
           specified commands.

           If the sudoedit option was enabled in the settings array passed to the open() function, the user has
           requested sudoedit mode.  sudoedit is a mechanism for editing one or more files where an editor is
           run with the user's credentials instead of with elevated privileges.  sudo achieves this by creating
           user-writable temporary copies of the files to be edited and then overwriting the originals with the
           temporary copies after editing is complete.  If the plugin supports sudoedit, it should choose the
           editor to be used, potentially from a variable in the user's environment, such as EDITOR, and include
           it in argv_out (note that environment variables may include command line flags).  The files to be
           edited should be copied from argv into argv_out, separated from the editor and its arguments by a
           “--” element.  The “--” will be removed by sudo before the editor is executed.  The plugin should
           also set sudoedit=true in the command_info list.

           The check_policy() function returns 1 if the command is allowed, 0 if not allowed, -1 for a general
           error, or -2 for a usage error or if sudoedit was specified but is unsupported by the plugin.  In the
           latter case, sudo will print a usage message before it exits.  If an error occurs, the plugin may
           optionally call the conversation() or plugin_printf() function with SUDO_CONF_ERROR_MSG to present
           additional error information to the user.

           The function arguments are as follows:

           argc  The number of elements in argv, not counting the final NULL pointer.

           argv  The argument vector describing the command the user wishes to run, in the same form as what
                 would be passed to the execve(2) system call.  The vector is terminated by a NULL pointer.

           env_add
                 Additional environment variables specified by the user on the command line in the form of a
                 NULL-terminated vector of “name=value” strings.  The plugin may reject the command if one or
                 more variables are not allowed to be set, or it may silently ignore such variables.

                 When parsing env_add, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

           command_info
                 Information about the command being run in the form of “name=value” strings.  These values are
                 used by sudo to set the execution environment when running a command.  The plugin is
                 responsible for creating and populating the vector, which must be terminated with a NULL
                 pointer.  The following values are recognized by sudo:

                 chroot=string
                       The root directory to use when running the command.

                 closefrom=number
                       If specified, sudo will close all files descriptors with a value of number or higher.

                 command=string
                       Fully qualified path to the command to be executed.

                 cwd=string
                       The current working directory to change to when executing the command.

                 exec_background=bool
                       By default, sudo runs a command as the foreground process as long as sudo itself is
                       running in the foreground.  When exec_background is enabled and the command is being run
                       in a pty (due to I/O logging or the use_pty setting), the command will be run as a
                       background process.  Attempts to read from the controlling terminal (or to change
                       terminal settings) will result in the command being suspended with the SIGTTIN signal (or
                       SIGTTOU in the case of terminal settings).  If this happens when sudo is a foreground
                       process, the command will be granted the controlling terminal and resumed in the
                       foreground with no user intervention required.  The advantage of initially running the
                       command in the background is that sudo need not read from the terminal unless the command
                       explicitly requests it.  Otherwise, any terminal input must be passed to the command,
                       whether it has required it or not (the kernel buffers terminals so it is not possible to
                       tell whether the command really wants the input).  This is different from historic sudo
                       behavior or when the command is not being run in a pty.

                       For this to work seamlessly, the operating system must support the automatic restarting
                       of system calls.  Unfortunately, not all operating systems do this by default, and even
                       those that do may have bugs.  For example, Mac OS X fails to restart the tcgetattr() and
                       tcsetattr() system calls (this is a bug in Mac OS X).  Furthermore, because this behavior
                       depends on the command stopping with the SIGTTIN or SIGTTOU signals, programs that catch
                       these signals and suspend themselves with a different signal (usually SIGTOP) will not be
                       automatically foregrounded.  Some versions of the linux su(1) command behave this way.
                       Because of this, a plugin should not set exec_background unless it is explicitly enabled
                       by the administrator and there should be a way to enabled or disable it on a per-command
                       basis.

                       This setting has no effect unless I/O logging is enabled or use_pty is enabled.

                 execfd=number
                       If specified, sudo will use the fexecve(2) system call to execute the command instead of
                       execve(2).  The specified number must refer to an open file descriptor.

                 iolog_compress=bool
                       Set to true if the I/O logging plugins, if any, should compress the log data.  This is a
                       hint to the I/O logging plugin which may choose to ignore it.

                 iolog_path=string
                       Fully qualified path to the file or directory in which I/O log is to be stored.  This is
                       a hint to the I/O logging plugin which may choose to ignore it.  If no I/O logging plugin
                       is loaded, this setting has no effect.

                 iolog_stdin=bool
                       Set to true if the I/O logging plugins, if any, should log the standard input if it is
                       not connected to a terminal device.  This is a hint to the I/O logging plugin which may
                       choose to ignore it.

                 iolog_stdout=bool
                       Set to true if the I/O logging plugins, if any, should log the standard output if it is
                       not connected to a terminal device.  This is a hint to the I/O logging plugin which may
                       choose to ignore it.

                 iolog_stderr=bool
                       Set to true if the I/O logging plugins, if any, should log the standard error if it is
                       not connected to a terminal device.  This is a hint to the I/O logging plugin which may
                       choose to ignore it.

                 iolog_ttyin=bool
                       Set to true if the I/O logging plugins, if any, should log all terminal input.  This only
                       includes input typed by the user and not from a pipe or redirected from a file.  This is
                       a hint to the I/O logging plugin which may choose to ignore it.

                 iolog_ttyout=bool
                       Set to true if the I/O logging plugins, if any, should log all terminal output.  This
                       only includes output to the screen, not output to a pipe or file.  This is a hint to the
                       I/O logging plugin which may choose to ignore it.

                 login_class=string
                       BSD login class to use when setting resource limits and nice value (optional).  This
                       option is only set on systems that support login classes.

                 nice=int
                       Nice value (priority) to use when executing the command.  The nice value, if specified,
                       overrides the priority associated with the login_class on BSD systems.

                 noexec=bool
                       If set, prevent the command from executing other programs.

                 preserve_fds=list
                       A comma-separated list of file descriptors that should be preserved, regardless of the
                       value of the closefrom setting.  Only available starting with API version 1.5.

                 preserve_groups=bool
                       If set, sudo will preserve the user's group vector instead of initializing the group
                       vector based on runas_user.

                 runas_egid=gid
                       Effective group ID to run the command as.  If not specified, the value of runas_gid is
                       used.

                 runas_euid=uid
                       Effective user ID to run the command as.  If not specified, the value of runas_uid is
                       used.

                 runas_gid=gid
                       Group ID to run the command as.

                 runas_groups=list
                       The supplementary group vector to use for the command in the form of a comma-separated
                       list of group IDs.  If preserve_groups is set, this option is ignored.

                 runas_uid=uid
                       User ID to run the command as.

                 selinux_role=string
                       SELinux role to use when executing the command.

                 selinux_type=string
                       SELinux type to use when executing the command.

                 set_utmp=bool
                       Create a utmp (or utmpx) entry when a pseudo-tty is allocated.  By default, the new entry
                       will be a copy of the user's existing utmp entry (if any), with the tty, time, type and
                       pid fields updated.

                 sudoedit=bool
                       Set to true when in sudoedit mode.  The plugin may enable sudoedit mode even if sudo was
                       not invoked as sudoedit.  This allows the plugin to perform command substitution and
                       transparently enable sudoedit when the user attempts to run an editor.

                 sudoedit_checkdir=bool
                       Set to false to disable directory writability checks in sudoedit.  By default, sudoedit
                       1.8.16 and higher will check all directory components of the path to be edited for
                       writability by the invoking user.  Symbolic links will not be followed in writable
                       directories and sudoedit will refuse to edit a file located in a writable directory.
                       These restrictions are not enforced when sudoedit is run by root.  The sudoedit_follow
                       option can be set to false to disable this check.  Only available starting with API
                       version 1.8.

                 sudoedit_follow=bool
                       Set to true to allow sudoedit to edit files that are symbolic links.  By default,
                       sudoedit 1.8.15 and higher will refuse to open a symbolic link.  The sudoedit_follow
                       option can be used to restore the older behavior and allow sudoedit to open symbolic
                       links.  Only available starting with API version 1.8.

                 timeout=int
                       Command timeout.  If non-zero then when the timeout expires the command will be killed.

                 umask=octal
                       The file creation mask to use when executing the command.

                 use_pty=bool
                       Allocate a pseudo-tty to run the command in, regardless of whether or not I/O logging is
                       in use.  By default, sudo will only run the command in a pty when an I/O log plugin is
                       loaded.

                 utmp_user=string
                       User name to use when constructing a new utmp (or utmpx) entry when set_utmp is enabled.
                       This option can be used to set the user field in the utmp entry to the user the command
                       runs as rather than the invoking user.  If not set, sudo will base the new entry on the
                       invoking user's existing entry.

                 Unsupported values will be ignored.

           argv_out
                 The NULL-terminated argument vector to pass to the execve(2) system call when executing the
                 command.  The plugin is responsible for allocating and populating the vector.

           user_env_out
                 The NULL-terminated environment vector to use when executing the command.  The plugin is
                 responsible for allocating and populating the vector.

     list
           int (*list)(int verbose, const char *list_user,
                       int argc, char * const argv[]);

           List available privileges for the invoking user.  Returns 1 on success, 0 on failure and -1 on error.
           On error, the plugin may optionally call the conversation() or plugin_printf() function with
           SUDO_CONF_ERROR_MSG to present additional error information to the user.

           Privileges should be output via the conversation() or plugin_printf() function using
           SUDO_CONV_INFO_MSG,

           verbose
                 Flag indicating whether to list in verbose mode or not.

           list_user
                 The name of a different user to list privileges for if the policy allows it.  If NULL, the
                 plugin should list the privileges of the invoking user.

           argc  The number of elements in argv, not counting the final NULL pointer.

           argv  If non-NULL, an argument vector describing a command the user wishes to check against the
                 policy in the same form as what would be passed to the execve(2) system call.  If the command
                 is permitted by the policy, the fully-qualified path to the command should be displayed along
                 with any command line arguments.

     validate
           int (*validate)(void);

           The validate() function is called when sudo is run with the -v flag.  For policy plugins such as
           sudoers that cache authentication credentials, this function will validate and cache the credentials.

           The validate() function should be NULL if the plugin does not support credential caching.

           Returns 1 on success, 0 on failure and -1 on error.  On error, the plugin may optionally call the
           conversation() or plugin_printf() function with SUDO_CONF_ERROR_MSG to present additional error
           information to the user.

     invalidate
           void (*invalidate)(int remove);

           The invalidate() function is called when sudo is called with the -k or -K flag.  For policy plugins
           such as sudoers that cache authentication credentials, this function will invalidate the credentials.
           If the remove flag is set, the plugin may remove the credentials instead of simply invalidating them.

           The invalidate() function should be NULL if the plugin does not support credential caching.

     init_session
           int (*init_session)(struct passwd *pwd, char **user_envp[);

           The init_session() function is called before sudo sets up the execution environment for the command.
           It is run in the parent sudo process and before any uid or gid changes.  This can be used to perform
           session setup that is not supported by command_info, such as opening the PAM session.  The close()
           function can be used to tear down the session that was opened by init_session.

           The pwd argument points to a passwd struct for the user the command will be run as if the uid the
           command will run as was found in the password database, otherwise it will be NULL.

           The user_env argument points to the environment the command will run in, in the form of a
           NULL-terminated vector of “name=value” strings.  This is the same string passed back to the front end
           via the Policy Plugin's user_env_out parameter.  If the init_session() function needs to modify the
           user environment, it should update the pointer stored in user_env.  The expected use case is to merge
           the contents of the PAM environment (if any) with the contents of user_env.  NOTE: the user_env
           parameter is only available starting with API version 1.2.  A plugin must check the API version
           specified by the sudo front end before using user_env.  Failure to do so may result in a crash.

           Returns 1 on success, 0 on failure and -1 on error.  On error, the plugin may optionally call the
           conversation() or plugin_printf() function with SUDO_CONF_ERROR_MSG to present additional error
           information to the user.

     register_hooks
           void (*register_hooks)(int version,
              int (*register_hook)(struct sudo_hook *hook));

           The register_hooks() function is called by the sudo front end to register any hooks the plugin needs.
           If the plugin does not support hooks, register_hooks should be set to the NULL pointer.

           The version argument describes the version of the hooks API supported by the sudo front end.

           The register_hook() function should be used to register any supported hooks the plugin needs.  It
           returns 0 on success, 1 if the hook type is not supported and -1 if the major version in struct hook
           does not match the front end's major hook API version.

           See the Hook function API section below for more information about hooks.

           NOTE: the register_hooks() function is only available starting with API version 1.2.  If the sudo
           front end doesn't support API version 1.2 or higher, register_hooks will not be called.

     deregister_hooks
           void (*deregister_hooks)(int version,
              int (*deregister_hook)(struct sudo_hook *hook));

           The deregister_hooks() function is called by the sudo front end to deregister any hooks the plugin
           has registered.  If the plugin does not support hooks, deregister_hooks should be set to the NULL
           pointer.

           The version argument describes the version of the hooks API supported by the sudo front end.

           The deregister_hook() function should be used to deregister any hooks that were put in place by the
           register_hook() function.  If the plugin tries to deregister a hook that the front end does not
           support, deregister_hook will return an error.

           See the Hook function API section below for more information about hooks.

           NOTE: the deregister_hooks() function is only available starting with API version 1.2.  If the sudo
           front end doesn't support API version 1.2 or higher, deregister_hooks will not be called.

     Policy Plugin Version Macros

     /* Plugin API version major/minor. */
     #define SUDO_API_VERSION_MAJOR 1
     #define SUDO_API_VERSION_MINOR 2
     #define SUDO_API_MKVERSION(x, y) ((x << 16) | y)
     #define SUDO_API_VERSION SUDO_API_MKVERSION(SUDO_API_VERSION_MAJOR,\
                                                 SUDO_API_VERSION_MINOR)

     /* Getters and setters for API version */
     #define SUDO_API_VERSION_GET_MAJOR(v) ((v) >> 16)
     #define SUDO_API_VERSION_GET_MINOR(v) ((v) & 0xffff)
     #define SUDO_API_VERSION_SET_MAJOR(vp, n) do { \
         *(vp) = (*(vp) & 0x0000ffff) | ((n) << 16); \
     } while(0)
     #define SUDO_API_VERSION_SET_MINOR(vp, n) do { \
         *(vp) = (*(vp) & 0xffff0000) | (n); \
     } while(0)

   I/O plugin API
     struct io_plugin {
     #define SUDO_IO_PLUGIN 2
         unsigned int type; /* always SUDO_IO_PLUGIN */
         unsigned int version; /* always SUDO_API_VERSION */
         int (*open)(unsigned int version, sudo_conv_t conversation,
                     sudo_printf_t plugin_printf, char * const settings[],
                     char * const user_info[], char * const command_info[],
                     int argc, char * const argv[], char * const user_env[],
                     char * const plugin_options[]);
         void (*close)(int exit_status, int error); /* wait status or error */
         int (*show_version)(int verbose);
         int (*log_ttyin)(const char *buf, unsigned int len);
         int (*log_ttyout)(const char *buf, unsigned int len);
         int (*log_stdin)(const char *buf, unsigned int len);
         int (*log_stdout)(const char *buf, unsigned int len);
         int (*log_stderr)(const char *buf, unsigned int len);
         void (*register_hooks)(int version,
            int (*register_hook)(struct sudo_hook *hook));
         void (*deregister_hooks)(int version,
            int (*deregister_hook)(struct sudo_hook *hook));
     };

     When an I/O plugin is loaded, sudo runs the command in a pseudo-tty.  This makes it possible to log the
     input and output from the user's session.  If any of the standard input, standard output or standard error
     do not correspond to a tty, sudo will open a pipe to capture the I/O for logging before passing it on.

     The log_ttyin function receives the raw user input from the terminal device (note that this will include
     input even when echo is disabled, such as when a password is read).  The log_ttyout function receives
     output from the pseudo-tty that is suitable for replaying the user's session at a later time.  The
     log_stdin(), log_stdout() and log_stderr() functions are only called if the standard input, standard output
     or standard error respectively correspond to something other than a tty.

     Any of the logging functions may be set to the NULL pointer if no logging is to be performed.  If the open
     function returns 0, no I/O will be sent to the plugin.

     If a logging function returns an error (-1), the running command will be terminated and all of the plugin's
     logging functions will be disabled.  Other I/O logging plugins will still receive any remaining input or
     output that has not yet been processed.

     If an input logging function rejects the data by returning 0, the command will be terminated and the data
     will not be passed to the command, though it will still be sent to any other I/O logging plugins.  If an
     output logging function rejects the data by returning 0, the command will be terminated and the data will
     not be written to the terminal, though it will still be sent to any other I/O logging plugins.

     The io_plugin struct has the following fields:

     type  The type field should always be set to SUDO_IO_PLUGIN.

     version
           The version field should be set to SUDO_API_VERSION.

           This allows sudo to determine the API version the plugin was built against.

     open
           int (*open)(unsigned int version, sudo_conv_t conversation,
                       sudo_printf_t plugin_printf, char * const settings[],
                       char * const user_info[], int argc, char * const argv[],
                       char * const user_env[], char * const plugin_options[]);

           The open() function is run before the log_ttyin(), log_ttyout(), log_stdin(), log_stdout(),
           log_stderr(), or show_version() functions are called.  It is only called if the version is being
           requested or if the policy plugin's check_policy() function has returned successfully.  It returns 1
           on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error.  In the
           latter case, sudo will print a usage message before it exits.  If an error occurs, the plugin may
           optionally call the conversation() or plugin_printf() function with SUDO_CONF_ERROR_MSG to present
           additional error information to the user.

           The function arguments are as follows:

           version
                 The version passed in by sudo allows the plugin to determine the major and minor version number
                 of the plugin API supported by sudo.

           conversation
                 A pointer to the conversation() function that may be used by the show_version() function to
                 display version information (see show_version() below).  The conversation() function may also
                 be used to display additional error message to the user.  The conversation() function returns 0
                 on success and -1 on failure.

           plugin_printf
                 A pointer to a printf()-style function that may be used by the show_version() function to
                 display version information (see show_version below).  The plugin_printf() function may also be
                 used to display additional error message to the user.  The plugin_printf() function returns
                 number of characters printed on success and -1 on failure.

           settings
                 A vector of user-supplied sudo settings in the form of “name=value” strings.  The vector is
                 terminated by a NULL pointer.  These settings correspond to flags the user specified when
                 running sudo.  As such, they will only be present when the corresponding flag has been
                 specified on the command line.

                 When parsing settings, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

                 See the Policy plugin API section for a list of all possible settings.

           user_info
                 A vector of information about the user running the command in the form of “name=value” strings.
                 The vector is terminated by a NULL pointer.

                 When parsing user_info, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

                 See the Policy plugin API section for a list of all possible strings.

           argc  The number of elements in argv, not counting the final NULL pointer.

           argv  If non-NULL, an argument vector describing a command the user wishes to run in the same form as
                 what would be passed to the execve(2) system call.

           user_env
                 The user's environment in the form of a NULL-terminated vector of “name=value” strings.

                 When parsing user_env, the plugin should split on the first equal sign (‘=’) since the name
                 field will never include one itself but the value might.

           plugin_options
                 Any (non-comment) strings immediately after the plugin path are treated as arguments to the
                 plugin.  These arguments are split on a white space boundary and are passed to the plugin in
                 the form of a NULL-terminated array of strings.  If no arguments were specified, plugin_options
                 will be the NULL pointer.

                 NOTE: the plugin_options parameter is only available starting with API version 1.2.  A plugin
                 must check the API version specified by the sudo front end before using plugin_options.
                 Failure to do so may result in a crash.

     close
           void (*close)(int exit_status, int error);

           The close() function is called when the command being run by sudo finishes.

           The function arguments are as follows:

           exit_status
                 The command's exit status, as returned by the wait(2) system call.  The value of exit_status is
                 undefined if error is non-zero.

           error
                 If the command could not be executed, this is set to the value of errno set by the execve(2)
                 system call.  If the command was successfully executed, the value of error is 0.

     show_version
           int (*show_version)(int verbose);

           The show_version() function is called by sudo when the user specifies the -V option.  The plugin may
           display its version information to the user via the conversation() or plugin_printf() function using
           SUDO_CONV_INFO_MSG.  If the user requests detailed version information, the verbose flag will be set.

     log_ttyin
           int (*log_ttyin)(const char *buf, unsigned int len);

           The log_ttyin() function is called whenever data can be read from the user but before it is passed to
           the running command.  This allows the plugin to reject data if it chooses to (for instance if the
           input contains banned content).  Returns 1 if the data should be passed to the command, 0 if the data
           is rejected (which will terminate the running command) or -1 if an error occurred.

           The function arguments are as follows:

           buf   The buffer containing user input.

           len   The length of buf in bytes.

     log_ttyout
           int (*log_ttyout)(const char *buf, unsigned int len);

           The log_ttyout() function is called whenever data can be read from the command but before it is
           written to the user's terminal.  This allows the plugin to reject data if it chooses to (for instance
           if the output contains banned content).  Returns 1 if the data should be passed to the user, 0 if the
           data is rejected (which will terminate the running command) or -1 if an error occurred.

           The function arguments are as follows:

           buf   The buffer containing command output.

           len   The length of buf in bytes.

     log_stdin
           int (*log_stdin)(const char *buf, unsigned int len);

           The log_stdin() function is only used if the standard input does not correspond to a tty device.  It
           is called whenever data can be read from the standard input but before it is passed to the running
           command.  This allows the plugin to reject data if it chooses to (for instance if the input contains
           banned content).  Returns 1 if the data should be passed to the command, 0 if the data is rejected
           (which will terminate the running command) or -1 if an error occurred.

           The function arguments are as follows:

           buf   The buffer containing user input.

           len   The length of buf in bytes.

     log_stdout
           int (*log_stdout)(const char *buf, unsigned int len);

           The log_stdout() function is only used if the standard output does not correspond to a tty device.
           It is called whenever data can be read from the command but before it is written to the standard
           output.  This allows the plugin to reject data if it chooses to (for instance if the output contains
           banned content).  Returns 1 if the data should be passed to the user, 0 if the data is rejected
           (which will terminate the running command) or -1 if an error occurred.

           The function arguments are as follows:

           buf   The buffer containing command output.

           len   The length of buf in bytes.

     log_stderr
           int (*log_stderr)(const char *buf, unsigned int len);

           The log_stderr() function is only used if the standard error does not correspond to a tty device.  It
           is called whenever data can be read from the command but before it is written to the standard error.
           This allows the plugin to reject data if it chooses to (for instance if the output contains banned
           content).  Returns 1 if the data should be passed to the user, 0 if the data is rejected (which will
           terminate the running command) or -1 if an error occurred.

           The function arguments are as follows:

           buf   The buffer containing command output.

           len   The length of buf in bytes.

     register_hooks
           See the Policy plugin API section for a description of register_hooks.

     deregister_hooks
           See the Policy plugin API section for a description of deregister_hooks.

     I/O Plugin Version Macros

     Same as for the Policy plugin API.

   Signal handlers
     The sudo front end installs default signal handlers to trap common signals while the plugin functions are
     run.  The following signals are trapped by default before the command is executed:

        SIGALRM
        SIGHUP
        SIGINT
        SIGQUIT
        SIGTERM
        SIGTSTP
        SIGUSR1
        SIGUSR2

     If a fatal signal is received before the command is executed, sudo will call the plugin's close() function
     with an exit status of 128 plus the value of the signal that was received.  This allows for consistent
     logging of commands killed by a signal for plugins that log such information in their close() function.

     A plugin may temporarily install its own signal handlers but must restore the original handler before the
     plugin function returns.

   Hook function API
     Beginning with plugin API version 1.2, it is possible to install hooks for certain functions called by the
     sudo front end.

     Currently, the only supported hooks relate to the handling of environment variables.  Hooks can be used to
     intercept attempts to get, set, or remove environment variables so that these changes can be reflected in
     the version of the environment that is used to execute a command.  A future version of the API will support
     hooking internal sudo front end functions as well.

     Hook structure

     Hooks in sudo are described by the following structure:

     typedef int (*sudo_hook_fn_t)();

     struct sudo_hook {
         unsigned int hook_version;
         unsigned int hook_type;
         sudo_hook_fn_t hook_fn;
         void *closure;
     };

     The sudo_hook structure has the following fields:

     hook_version
           The hook_version field should be set to SUDO_HOOK_VERSION.

     hook_type
           The hook_type field may be one of the following supported hook types:

           SUDO_HOOK_SETENV
                 The C library setenv(3) function.  Any registered hooks will run before the C library
                 implementation.  The hook_fn field should be a function that matches the following typedef:

                 typedef int (*sudo_hook_fn_setenv_t)(const char *name,
                    const char *value, int overwrite, void *closure);

                 If the registered hook does not match the typedef the results are unspecified.

           SUDO_HOOK_UNSETENV
                 The C library unsetenv(3) function.  Any registered hooks will run before the C library
                 implementation.  The hook_fn field should be a function that matches the following typedef:

                 typedef int (*sudo_hook_fn_unsetenv_t)(const char *name,
                    void *closure);

           SUDO_HOOK_GETENV
                 The C library getenv(3) function.  Any registered hooks will run before the C library
                 implementation.  The hook_fn field should be a function that matches the following typedef:

                 typedef int (*sudo_hook_fn_getenv_t)(const char *name,
                    char **value, void *closure);

                 If the registered hook does not match the typedef the results are unspecified.

           SUDO_HOOK_PUTENV
                 The C library putenv(3) function.  Any registered hooks will run before the C library
                 implementation.  The hook_fn field should be a function that matches the following typedef:

                 typedef int (*sudo_hook_fn_putenv_t)(char *string,
                    void *closure);

                 If the registered hook does not match the typedef the results are unspecified.

     hook_fn
           sudo_hook_fn_t hook_fn;

           The hook_fn field should be set to the plugin's hook implementation.  The actual function arguments
           will vary depending on the hook_type (see hook_type above).  In all cases, the closure field of
           struct sudo_hook is passed as the last function parameter.  This can be used to pass arbitrary data
           to the plugin's hook implementation.

           The function return value may be one of the following:

           SUDO_HOOK_RET_ERROR
                 The hook function encountered an error.

           SUDO_HOOK_RET_NEXT
                 The hook completed without error, go on to the next hook (including the native implementation
                 if applicable).  For example, a getenv(3) hook might return SUDO_HOOK_RET_NEXT if the specified
                 variable was not found in the private copy of the environment.

           SUDO_HOOK_RET_STOP
                 The hook completed without error, stop processing hooks for this invocation.  This can be used
                 to replace the native implementation.  For example, a setenv hook that operates on a private
                 copy of the environment but leaves environ unchanged.

     Note that it is very easy to create an infinite loop when hooking C library functions.  For example, a
     getenv(3) hook that calls the snprintf(3) function may create a loop if the snprintf(3) implementation
     calls getenv(3) to check the locale.  To prevent this, you may wish to use a static variable in the hook
     function to guard against nested calls.  For example:

     static int in_progress = 0; /* avoid recursion */
     if (in_progress)
         return SUDO_HOOK_RET_NEXT;
     in_progress = 1;
     ...
     in_progress = 0;
     return SUDO_HOOK_RET_STOP;

     Hook API Version Macros

     /* Hook API version major/minor */
     #define SUDO_HOOK_VERSION_MAJOR 1
     #define SUDO_HOOK_VERSION_MINOR 0
     #define SUDO_HOOK_VERSION SUDO_API_MKVERSION(SUDO_HOOK_VERSION_MAJOR,\
                                                   SUDO_HOOK_VERSION_MINOR)

     For getters and setters see the Policy plugin API.

   Remote command execution
     The sudo front end does not have native support for running remote commands.  However, starting with sudo
     1.8.8, the -h option may be used to specify a remote host that is passed to the policy plugin.  A plugin
     may also accept a runas_user in the form of “user@hostname” which will work with older versions of sudo.
     It is anticipated that remote commands will be supported by executing a “helper” program.  The policy
     plugin should setup the execution environment such that the sudo front end will run the helper which, in
     turn, will connect to the remote host and run the command.

     For example, the policy plugin could utilize ssh to perform remote command execution.  The helper program
     would be responsible for running ssh with the proper options to use a private key or certificate that the
     remote host will accept and run a program on the remote host that would setup the execution environment
     accordingly.

     Note that remote sudoedit functionality must be handled by the policy plugin, not sudo itself as the front
     end has no knowledge that a remote command is being executed.  This may be addressed in a future revision
     of the plugin API.

   Conversation API
     If the plugin needs to interact with the user, it may do so via the conversation() function.  A plugin
     should not attempt to read directly from the standard input or the user's tty (neither of which are
     guaranteed to exist).  The caller must include a trailing newline in msg if one is to be printed.

     A printf()-style function is also available that can be used to display informational or error messages to
     the user, which is usually more convenient for simple messages where no use input is required.

     Conversation function structures

     The conversation function takes as arguments pointers to the following structures:

     struct sudo_conv_message {
     #define SUDO_CONV_PROMPT_ECHO_OFF  0x0001 /* do not echo user input */
     #define SUDO_CONV_PROMPT_ECHO_ON   0x0002 /* echo user input */
     #define SUDO_CONV_ERROR_MSG        0x0003 /* error message */
     #define SUDO_CONV_INFO_MSG         0x0004 /* informational message */
     #define SUDO_CONV_PROMPT_MASK      0x0005 /* mask user input */
     #define SUDO_CONV_PROMPT_ECHO_OK   0x1000 /* flag: allow echo if no tty */
         int msg_type;
         int timeout;
         const char *msg;
     };

     #define SUDO_CONV_REPL_MAX      255

     struct sudo_conv_reply {
         char *reply;
     };

     typedef int (*sudo_conv_callback_fn_t)(int signo, void *closure);
     struct sudo_conv_callback {
         unsigned int version;
         void *closure;
         sudo_conv_callback_fn_t on_suspend;
         sudo_conv_callback_fn_t on_resume;
     };

     Pointers to the conversation() and printf()-style functions are passed in to the plugin's open() function
     when the plugin is initialized.  The following type definitions can be used in the declaration of the
     open() function:

     typedef int (*sudo_conv_t)(int num_msgs,
                  const struct sudo_conv_message msgs[],
                  struct sudo_conv_reply replies[],
                  struct sudo_conv_callback *callback);

     typedef int (*sudo_printf_t)(int msg_type, const char *fmt, ...);

     To use the conversation() function, the plugin must pass an array of sudo_conv_message and sudo_conv_reply
     structures.  There must be a struct sudo_conv_message and struct sudo_conv_reply for each message in the
     conversation.  The struct sudo_conv_callback pointer, if not NULL, should contain function pointers to be
     called when the sudo process is suspended and/or resumed during conversation input.  The on_suspend and
     on_resume functions are called with the signal that caused sudo to be suspended and the closure pointer
     from the struct sudo_conv_callback.  These functions should return 0 on success and -1 on error.  On error,
     the conversation will end and the conversation function will return a value of -1.  The intended use is to
     allow the plugin to release resources, such as locks, that should not be held indefinitely while suspended
     and then reacquire them when the process is resumed.  Note that the functions are not actually invoked from
     within a signal handler.

     The plugin is responsible for freeing the reply buffer located in each struct sudo_conv_reply, if it is not
     NULL.  SUDO_CONV_REPL_MAX represents the maximum length of the reply buffer (not including the trailing NUL
     character).  In practical terms, this is the longest password sudo will support.  It is also useful as a
     maximum value for the memset_s() function when clearing passwords filled in by the conversation function.

     The printf()-style function uses the same underlying mechanism as the conversation() function but only
     supports SUDO_CONV_INFO_MSG and SUDO_CONV_ERROR_MSG for the msg_type parameter.  It can be more convenient
     than using the conversation() function if no user reply is needed and supports standard printf() escape
     sequences.

     See the sample plugin for an example of the conversation() function usage.

   Sudoers group plugin API
     The sudoers plugin supports its own plugin interface to allow non-Unix group lookups.  This can be used to
     query a group source other than the standard Unix group database.  Two sample group plugins are bundled
     with sudo, group_file and system_group, are detailed in sudoers(5).  Third party group plugins include a
     QAS AD plugin available from Quest Software.

     A group plugin must declare and populate a sudoers_group_plugin struct in the global scope.  This structure
     contains pointers to the functions that implement plugin initialization, cleanup and group lookup.

     struct sudoers_group_plugin {
        unsigned int version;
        int (*init)(int version, sudo_printf_t sudo_printf,
                    char *const argv[]);
        void (*cleanup)(void);
        int (*query)(const char *user, const char *group,
                     const struct passwd *pwd);
     };

     The sudoers_group_plugin struct has the following fields:

     version
           The version field should be set to GROUP_API_VERSION.

           This allows sudoers to determine the API version the group plugin was built against.

     init
           int (*init)(int version, sudo_printf_t plugin_printf,
                       char *const argv[]);

           The init() function is called after sudoers has been parsed but before any policy checks.  It returns
           1 on success, 0 on failure (or if the plugin is not configured), and -1 if a error occurred.  If an
           error occurs, the plugin may call the plugin_printf() function with SUDO_CONF_ERROR_MSG to present
           additional error information to the user.

           The function arguments are as follows:

           version
                 The version passed in by sudoers allows the plugin to determine the major and minor version
                 number of the group plugin API supported by sudoers.

           plugin_printf
                 A pointer to a printf()-style function that may be used to display informational or error
                 message to the user.  Returns the number of characters printed on success and -1 on failure.

           argv  A NULL-terminated array of arguments generated from the group_plugin option in sudoers.  If no
                 arguments were given, argv will be NULL.

     cleanup
           void (*cleanup)();

           The cleanup() function is called when sudoers has finished its group checks.  The plugin should free
           any memory it has allocated and close open file handles.

     query
           int (*query)(const char *user, const char *group,
                        const struct passwd *pwd);

           The query() function is used to ask the group plugin whether user is a member of group.

           The function arguments are as follows:

           user  The name of the user being looked up in the external group database.

           group
                 The name of the group being queried.

           pwd   The password database entry for user, if any.  If user is not present in the password database,
                 pwd will be NULL.

     Group API Version Macros

     /* Sudoers group plugin version major/minor */
     #define GROUP_API_VERSION_MAJOR 1
     #define GROUP_API_VERSION_MINOR 0
     #define GROUP_API_VERSION ((GROUP_API_VERSION_MAJOR << 16) | \
                                GROUP_API_VERSION_MINOR)
     For getters and setters see the Policy plugin API.

PLUGIN API CHANGELOG

     The following revisions have been made to the Sudo Plugin API.

     Version 1.0
           Initial API version.

     Version 1.1 (sudo 1.8.0)
           The I/O logging plugin's open() function was modified to take the command_info list as an argument.

     Version 1.2 (sudo 1.8.5)
           The Policy and I/O logging plugins' open() functions are now passed a list of plugin parameters if
           any are specified in sudo.conf(5).

           A simple hooks API has been introduced to allow plugins to hook in to the system's environment
           handling functions.

           The init_session Policy plugin function is now passed a pointer to the user environment which can be
           updated as needed.  This can be used to merge in environment variables stored in the PAM handle
           before a command is run.

     Version 1.3 (sudo 1.8.7)
           Support for the exec_background entry has been added to the command_info list.

           The max_groups and plugin_dir entries were added to the settings list.

           The version() and close() functions are now optional.  Previously, a missing version() or close()
           function would result in a crash.  If no policy plugin close() function is defined, a default close()
           function will be provided by the sudo front end that displays a warning if the command could not be
           executed.

           The sudo front end now installs default signal handlers to trap common signals while the plugin
           functions are run.

     Version 1.4 (sudo 1.8.8)
           The remote_host entry was added to the settings list.

     Version 1.5 (sudo 1.8.9)
           The preserve_fds entry was added to the command_info list.

     Version 1.6 (sudo 1.8.11)
           The behavior when an I/O logging plugin returns an error (-1) has changed.  Previously, the sudo
           front end took no action when the log_ttyin(), log_ttyout(), log_stdin(), log_stdout(), or
           log_stderr() function returned an error.

           The behavior when an I/O logging plugin returns 0 has changed.  Previously, output from the command
           would be displayed to the terminal even if an output logging function returned 0.

     Version 1.7 (sudo 1.8.12)
           The plugin_path entry was added to the settings list.

           The debug_flags entry now starts with a debug file path name and may occur multiple times if there
           are multiple plugin-specific Debug lines in the sudo.conf(5) file.

     Version 1.8 (sudo 1.8.15)
           The sudoedit_checkdir and sudoedit_follow entries were added to the command_info list.  The default
           value of sudoedit_checkdir was changed to true in sudo 1.8.16.

           The sudo conversation function now takes a pointer to a struct sudo_conv_callback as its fourth
           argument.  The sudo_conv_t definition has been updated to match.  The plugin must specify that it
           supports plugin API version 1.8 or higher to receive a conversation function pointer that supports
           this argument.

     Version 1.9 (sudo 1.8.16)
           The execfd entry was added to the command_info list.

SEE ALSO

     sudo.conf(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 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, including, 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.