SUDO_PLUGIN_PYTHON(5)

NAME
sudo_plugin_python - Sudo Plugin API (Python)

DESCRIPTION
Starting with version 1.9, sudo plugins can be written in python. The API closely follows the C sudo plugin API described by sudo_plugin(5).

The supported plugins types are:

•   Policy plugin
•   I/O plugin
•   Audit plugin
•   Approval plugin
•   Group provider plugin

Python plugin support needs to be explicitly enabled at build time with the configure option “--enable-python”. Python version 3.0 or higher is required.

  Sudo Python Plugin Base
A plugin written in Python should be a class in a python file that inherits from sudo.Plugin. The sudo.Plugin base class has no real purpose other than to identify this class as a plugin.

The only implemented method is a constructor, which stores the keyword arguments it receives as fields (member variables) in the object. This is intended as a convenience to allow you to avoid writing the constructor yourself.

For example:

    import sudo
    class MySudoPlugin(sudo.Plugin):
        # example constructor (optional)
        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
        # example destructor (optional)
        def __del__(self):
            pass

Both the constructor and destructor are optional and can be omitted.

The customized Plugin class should define a few plugin-specific methods. When the plugin loads, sudo will create an instance of this class and call the methods. The actual methods required depend on the type of the plugin, but most return an int result code, as documented in sudo_plugin(5), that indicates whether or not the method was successful. The Python sudo module defines the following constants to improve readability:
Define | Value
sudo.RC.OK | 1
sudo.RC.ACCEPT | 1
sudo.RC.REJECT | 0
sudo.RC.ERROR | -1
sudo.RC.USAGE_ERROR | -2

If a function returns None (for example, if it does not call return), it will be considered to have returned sudo.RC.OK. If an exception is raised (other than sudo.PluginException), the backtrace will be shown to the user and the plugin function will return sudo.RC.ERROR. If that is not acceptable, you must catch the exception and handle it yourself.

Instead of just returning sudo.RC.ERROR or sudo.RC.REJECT result code the plugin can also provide a message describing the problem. This can be done by raising one of the special exceptions:

    raise sudo.PluginError("Message")
    raise sudo.PluginReject("Message")

This added message will be used by the audit plugins. Both exceptions inherit from sudo.PluginException

  Python Plugin Loader
Running the Python interpreter and bridging between C and Python is handled by the sudo plugin python_plugin.so. This shared object can be loaded like any other dynamic sudo plugin and should receive the path and the class name of the Python plugin it is loading as arguments.

Example usage in sudo.conf(5):

    Plugin python_policy python_plugin.so ModulePath=<path> ClassName=<class>
    Plugin python_io python_plugin.so ModulePath=<path> ClassName=<class>
    Plugin python_audit python_plugin.so ModulePath=<path> ClassName=<class>
    Plugin python_approval python_plugin.so ModulePath=<path> ClassName=<class>

Example group provider plugin usage in the sudoers file:

    Defaults group_plugin="python_plugin.so ModulePath=<path> ClassName=<class>"

The plugin arguments are as follows:

ModulePath
    The path of a python file which contains the class of the sudo Python plugin. It must be either an absolute path or a path relative to the sudo Python plugin directory, /usr/libexec/sudo/python. The parent directory of ModulePath will be appended to Python's module search path (there is currently no way to force Python to load a module from a fully-qualified path). It is good practice to use a prefix for the module file that is unlikely to conflict with other installed Python modules, for example, sudo_policy.py. Otherwise, if the there is an installed Python module with the same file name as the sudo Python plugin file (without the directory), the wrong file will be loaded.

ClassName
    (Optional.) The name of the class implementing the sudo Python plugin. If not supplied, the one and only sudo.Plugin that is present in the module will be used. If there are multiple such plugins in the module (or none), it will result in an error.

  Policy plugin API
Policy plugins must be registered in sudo.conf(5). For example:

    Plugin python_policy python_plugin.so ModulePath=<path> ClassName=<class>

Currently, only a single policy plugin may be specified in sudo.conf(5).

A policy plugin may have the following member functions:

constructor
        __init__(self, user_env: Tuple[str, ...], settings: Tuple[str, ...],
            version: str, user_info: Tuple[str, ...],
            plugin_options: Tuple[str, ...])

    Implementing this function is optional. The default constructor will set the keyword arguments it receives as member variables in the object.

    The constructor matches the open() function in the C sudo plugin API.

    The function arguments are as follows:

    user_env
        The user's environment as a tuple of strings in “key=value” format.

    settings
        A tuple of user-supplied sudo settings in the form of “key=value” strings.

    version
        The version of the Python Policy Plugin API.

    user_info
        A tuple of information about the user running the command in the form of “key=value” strings.

    plugin_options
        The plugin options passed as arguments in the sudo.conf(5) plugin registration. This is a tuple of strings, usually (but not necessarily) in “key=value” format.

    The sudo.options_as_dict() convenience function can be used to convert “key=value” pairs to a dictionary. For a list of recognized keys and their supported values, see the policy plugin open() documentation in sudo_plugin(5).

check_policy
        check_policy(self, argv: Tuple[str, ...], env_add: Tuple[str, ...])

    The check_policy() function is called by sudo to determine whether the user is allowed to run the specified command. Implementing this function is mandatory for a policy plugin.

    The function arguments are as follows:

    argv
        A tuple describing the command the user wishes to run.

    env_add
        Additional environment variables specified by the user on the command line in the form of a tuple of “key=value” pairs. The sudo.options_as_dict() convenience function can be used to convert them to a dictionary.

    This function should return a result code or a tuple in the following format:

        return (rc, command_info_out, argv_out, user_env_out)

    The tuple values are as follows:

    rc  The result of the policy check, one of the sudo.RC.* constants. sudo.RC.ACCEPT if the command is allowed, sudo.RC.REJECT if not allowed, sudo.RC.ERROR for a general error, or sudo.RC.USAGE_ERROR for a usage error.

    command_info_out
        Optional (only required when the command is accepted). Information about the command being run in the form of “key=value” strings.

        To accept a command, at the very minimum the plugin must set in the command, runas_uid, and runas_gid keys.

        For a list of recognized keys and supported values, see the check_policy() documentation in sudo_plugin(5).

    argv_out
        Optional (only required when the command is accepted). The arguments to pass to the execve(2) system call when executing the command.

    user_env_out
        Optional (only required when the command is accepted). The environment to use when executing the command in the form of a tuple of strings in “key=value” format.

init_session
        init_session(self, user_pwd: Tuple, user_env: Tuple[str, ...])

    Perform session setup (optional). The init_session() function is called before sudo sets up the execution environment for the command before any user-ID or group-ID changes.

    The function arguments are as follows:

    user_pwd
        A tuple describing the user's passwd entry. Convertible to pwd.struct_passwd or None if the user is not present in the password database.

        Example conversion:
            user_pwd = pwd.struct_passwd(user_pwd) if user_pwd else None

    user_env
        The environment the command will run in. This is a tuple of strings in “key=value” format.

    This function should return a result code or a tuple in the following format:

        return (rc, user_env_out)

    The tuple values are as follows:

    rc  The result of the session init, one of the sudo.RC.* constants. sudo.RC.OK on success, 0 on failure, or sudo.RC.ERROR if an error occurred.

    user_env_out
        Optional. If the init_session() function needs to modify the user environment, it can return the new environment in user_env_out. If this is omitted, no changes will be made to user_env.

list
        list(self, argv: Tuple[str, ...], is_verbose: int, user: str)

    List available privileges for the invoking user.

    The function arguments are as follows:

    argv
        If not set to None, an argument vector describing a command the user wishes to check against the policy.

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

    user
        The name of a different user to list privileges for if the policy allows it. If None, the plugin should list the privileges of the invoking user.

validate
        validate(self)

    For policy plugins that cache authentication credentials, this function is used to validate and cache the credentials (optional).

invalidate
        invalidate(self, remove: int)

    For policy plugins that cache authentication credentials, this function is used to invalidate the credentials (optional).

    The function arguments are as follows:

    remove
        If this flag is set, the plugin may remove the credentials instead of simply invalidating them.

show_version
        show_version(self, is_verbose: int)

    Display the plugin version information to the user. The sudo.log_info() function should be used.

    The function arguments are as follows:

    is_verbose
        A flag to indicate displaying more verbose information. Currently this is 1 if ‘sudo -V’ is run as the root user.

close
        close(self, exit_status: int, error: int)

    Called when a command finishes executing.

    Works the same as the close() function in the C sudo plugin API, except that it only gets called if sudo attempts to execute the command.

    The function arguments are as follows:

    exit_status
        The exit status of the command if was executed, otherwise -1.

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

  Policy plugin example
Sudo ships with an example Python policy plugin. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_policy python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_policy_plugin.py \
        ClassName=SudoPolicyPlugin

Only one policy plugin can be enabled at a time so you must disable any other policy plugin listed in /etc/sudo.conf, such as sudoers(5).

  I/O plugin API
I/O plugins must be registered in sudo.conf(5). For example:

    Plugin python_io python_plugin.so ModulePath=<path> ClassName=<class>

Sudo supports loading multiple I/O plugins. Currently only 8 python I/O plugins can be loaded at once.

An I/O plugin may have the following member functions:

constructor
        __init__(self, user_env: Tuple[str, ...], settings: Tuple[str, ...],
            version: str, user_info: Tuple[str, ...],
            plugin_options: Tuple[str, ...])

    Implementing this function is optional. The default constructor will set the keyword arguments it receives as member variables in the object.

    The constructor matches the open() function in the C sudo plugin API.

    The function arguments are as follows:

    user_env
        The user's environment as a tuple of strings in “key=value” format.

    settings
        A tuple of user-supplied sudo settings in the form of “key=value” strings.

    version
        The version of the Python I/O Plugin API.

    user_info
        A tuple of information about the user running the command in the form of “key=value” strings.

    plugin_options
        The plugin options passed as arguments in the sudo.conf(5) plugin registration. This is a tuple of strings, usually (but not necessarily) in “key=value” format.

    The sudo.options_as_dict() convenience function can be used to convert “key=value” pairs to a dictionary. For a list of recognized keys and their supported values, see the I/O plugin open() documentation in sudo_plugin(5).

open
        open(self, argv: Tuple[str, ...],
            command_info: Tuple[str, ...]) -> int

    Receives the command the user wishes to run.

    Works the same as the open() function in the C sudo plugin API except that:

    •   It only gets called when there is a command to be executed (and not for a version query for example).
    •   Other arguments of the C API open() function are received through the constructor.

    The function arguments are as follows:

    argv
        A tuple of the arguments describing the command the user wishes to run.

    command_info
        Information about the command being run in the form of “key=value” strings.

    The sudo.options_as_dict() convenience function can be used to convert “key=value” pairs to a dictionary. For a list of recognized keys and their supported values, see the I/O plugin open() documentation in sudo_plugin(5).

    The open() function should return a result code, one of the sudo.RC.* constants. If the function returns sudo.RC.REJECT, no I/O will be sent to the plugin.

log_ttyin, log_ttyout, log_stdin, log_stdout, log_stderr
        log_ttyin(self, buf: str) -> int
        log_ttyout(self, buf: str) -> int
        log_stdin(self, buf: str) -> int
        log_stdout(self, buf: str) -> int
        log_stderr(self, buf: str) -> int

    Receive the user input or output of the terminal device and application standard input, standard output, or standard error. See the matching calls in sudo_plugin(5).

    The function arguments are as follows:

    buf The input (or output) buffer in the form of a string.

    The function should return a result code, one of the sudo.RC.* constants.

    If sudo.RC.ERROR is returned, 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 sudo.RC.REJECT, 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 sudo.RC.REJECT, 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.

change_winsize
        change_winsize(self, line: int, cols: int) -> int

    Called whenever the window size of the terminal changes. The function arguments are as follows:

    line
        The number of lines of the terminal.

    cols
        The number of columns of the terminal.

log_suspend
        log_suspend(self, signo: int) -> int

    Called whenever a command is suspended or resumed.

    The function arguments are as follows:

    signo
        The number of the signal that caused the command to be suspended or SIGCONT if the command was resumed.

show_version
        show_version(self, is_verbose: int)

    Display the plugin version information to the user. The sudo.log_info() function should be used.

    The function arguments are as follows:

    is_verbose
        A flag to indicate displaying more verbose information. Currently this is 1 if ‘sudo -V’ is run as the root user.

close
        close(self, exit_status: int, error: int) -> None

    Called when a command finishes execution.

    Works the same as the close() function in the C sudo plugin API, except that it only gets called if sudo attempts to execute the command.

    The function arguments are as follows:

    exit_status
        The exit status of the command if was executed, otherwise -1.

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

  I/O plugin example
Sudo ships with a Python I/O plugin example. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_io python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_io_plugin.py \
        ClassName=SudoIOPlugin

  Audit plugin API
Audit plugins must be registered in sudo.conf(5). For example:

    Plugin python_audit python_plugin.so ModulePath=<path> ClassName=<class>

Sudo supports loading multiple audit plugins. Currently only 8 python audit plugins can be loaded at once.

An audit plugin may have the following member functions (all of which are optional):

constructor
        __init__(self, user_env: Tuple[str, ...], settings: Tuple[str, ...],
            version: str, user_info: Tuple[str, ...], plugin_options: Tuple[str, ...])

    The default constructor will set the keyword arguments it receives as member variables in the object.

    The constructor matches the open() function in the C sudo plugin API.

    The function arguments are as follows:

    user_env
        The user's environment as a tuple of strings in “key=value” format.

    settings
        A tuple of user-supplied sudo settings in the form of “key=value” strings.

    version
        The version of the Python Audit Plugin API.

    user_info
        A tuple of information about the user running the command in the form of “key=value” strings.

    plugin_options
        The plugin options passed as arguments in the sudo.conf(5) plugin registration. This is a tuple of strings, usually (but not necessarily) in “key=value” format.

open
        open(self, submit_optind: int,
            submit_argv: Tuple[str, ...]) -> int

    The function arguments are as follows:

    submit_optind
        The index into submit_argv that corresponds to the first entry that is not a command line option.

    submit_argv
        The argument vector sudo was invoked with, including all command line options.

close
        close(self, status_type: int, status: int) -> None

    Called when sudo is finished, shortly before it exits.

    The function arguments are as follows:

    status_type
        The type of status being passed. One of the sudo.EXIT_REASON.* constants.

    status
        Depending on the value of status_type, this value is either ignored, the command's exit status as returned by the wait(2) system call, the value of errno set by the execve(2) system call, or the value of errno resulting from an error in the sudo front-end.

show_version
        show_version(self, is_verbose: int) -> int

    Display the plugin version information to the user. The sudo.log_info() function should be used.

    The function arguments are as follows:

    is_verbose
        A flag to indicate displaying more verbose information. Currently this is 1 if ‘sudo -V’ is run as the root user.

accept
        accept(self, plugin_name: str, plugin_type: int, command_info: Tuple[str, ...],
               run_argv: Tuple[str, ...], run_envp: Tuple[str, ...]) -> int

    This function is called when a command or action is accepted by a policy or approval plugin. The function arguments are as follows:

    plugin_name
        The name of the plugin that accepted the command or “sudo” for the sudo front-end.

    plugin_type
        The type of plugin that accepted the command, currently either sudo.PLUGIN_TYPE.POLICY, sudo.PLUGIN_TYPE.APPROVAL, or sudo.PLUGIN_TYPE.SUDO. The accept() function is called multiple times--once for each policy or approval plugin that succeeds and once for the sudo front-end. When called on behalf of the sudo front-end, command_info may include information from an I/O logging plugin as well.

        Typically, an audit plugin is interested in either the accept status from the sudo front-end or from the various policy and approval plugins, but not both. It is possible for the policy plugin to accept a command that is later rejected by an approval plugin, in which case the audit plugin's accept() and reject() functions will both be called.

    command_info
        A vector of information describing the command being run. See the sudo_plugin(5) manual for possible values.

    run_argv
        Argument vector describing a command that will be run.

    run_envp
        The environment the command will be run with.

reject
        reject(self, plugin_name: str, plugin_type: int, audit_msg: str,
               command_info: Tuple[str, ...]) -> int

    This function is called when a command or action is rejected by the policy plugin. The function arguments are as follows:

    plugin_name
        The name of the plugin that rejected the command.

    plugin_type
        The type of plugin that rejected the command, currently either sudo.PLUGIN_TYPE.POLICY, sudo.PLUGIN_TYPE.APPROVAL, or sudo.PLUGIN_TYPE.IO.

        Unlike the accept() function, the reject() function is not called on behalf of the sudo front-end.

    audit_msg
        An optional string describing the reason the command was rejected by the plugin. If the plugin did not provide a reason, audit_msg will be None.

    command_info
        A vector of information describing the rejected command. See the sudo_plugin(5) manual for possible values.

error
        error(self, plugin_name: str, plugin_type: int, audit_msg: str,
              command_info: Tuple[str, ...]) -> int

    This function is called when a plugin or the sudo front-end returns an error. The function arguments are as follows:

    plugin_name
        The name of the plugin that generated the error or “sudo” for the sudo front-end.

    plugin_type
        The type of plugin that generated the error, or SUDO_FRONT_END for the sudo front-end.

    audit_msg
        An optional string describing the plugin error. If the plugin did not provide a description, it will be None.

    command_info
        A vector of information describing the command. See the sudo_plugin(5) manual for possible values.

  Audit plugin example
Sudo ships with a Python Audit plugin example. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_audit python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_audit_plugin.py \
        ClassName=SudoAuditPlugin

It will log the plugin accept / reject / error results to the output.

  Approval plugin API
Approval plugins must be registered in sudo.conf(5). For example:

    Plugin python_approval python_plugin.so ModulePath=<path> ClassName=<class>

Sudo supports loading multiple approval plugins. Currently only 8 python approval plugins can be loaded at once.

An approval plugin may have the following member functions:

constructor
        __init__(self, user_env: Tuple[str, ...], settings: Tuple[str, ...],
            version: str, user_info: Tuple[str, ...], plugin_options: Tuple[str, ...],
            submit_optind: int, submit_argv: Tuple[str, ...])

    Optional. The default constructor will set the keyword arguments it receives as member variables in the object.

    The constructor matches the open() function in the C sudo plugin API.

    The function arguments are as follows:

    user_env
        The user's environment as a tuple of strings in “key=value” format.

    settings
        A tuple of user-supplied sudo settings in the form of “key=value” strings.

    version
        The version of the Python Approval Plugin API.

    user_info
        A tuple of information about the user running the command in the form of “key=value” strings.

    plugin_options
        The plugin options passed as arguments in the sudo.conf(5) plugin registration. This is a tuple of strings, usually (but not necessarily) in “key=value” format.

    submit_optind
        The index into submit_argv that corresponds to the first entry that is not a command line option.

    submit_argv
        The argument vector sudo was invoked with, including all command line options.

show_version
        show_version(self, is_verbose: int) -> int

    Display the version. (Same as for all the other plugins.)

check
        check(self, command_info: Tuple[str, ...], run_argv: Tuple[str, ...],
              run_env: Tuple[str, ...]) -> int

    This function is called after policy plugin's check_policy has succeeded. It can reject execution of the command by returning sudo.RC.REJECT or raising the special exception:

        raise sudo.PluginReject("some message")

    with the message describing the problem. In the latter case, the audit plugins will get the description.

    The function arguments are as follows:

    command_info
        A vector of information describing the command that will run. See the sudo_plugin(5) manual for possible values.

    run_argv
        Argument vector describing a command that will be run.

    run_env
        The environment the command will be run with.

  Approval plugin example
Sudo ships with a Python Approval plugin example. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_approval python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_approval_plugin.py \
        ClassName=BusinessHoursApprovalPlugin

It will only allow execution of commands in the "business hours" (from Monday to Friday between 8:00 and 17:59:59).

  Sudoers group provider plugin API
A group provider plugin is registered in the sudoers(5) file. For example:

    Defaults group_plugin="python_plugin.so ModulePath=<path> ClassName=<class>"

Currently, only a single group plugin can be registered in sudoers.

A group provider plugin may have the following member functions:

constructor
        __init__(self, args: Tuple[str, ...], version: str)

    Implementing this function is optional. The default constructor will set the keyword arguments it receives as member variables in the object.

    The function arguments are as follows:

    args
        The plugin options passed as arguments in the sudoers file plugin registration. All the arguments are free form strings (not necessarily in “key=value” format).

    version
        The version of the Python Group Plugin API.

query
        query(self, user: str, group: str, user_pwd: Tuple)

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

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.

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

  Group plugin example
Sudo ships with a Python group plugin example. To try it, register it in the sudoers file by adding the following lines:

    Defaults group_plugin="python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_group_plugin.py \
        ClassName=SudoGroupPlugin"

The example plugin will tell sudo that the user test is part of the non-Unix group mygroup. If you add a rule that uses this group, it will affect the test user. For example:

    %:mygroup ALL=(ALL) NOPASSWD: ALL

Will allow user test to run sudo without a password.

  Hook function API
The hook function API is currently not supported for plugins written in Python.

  Conversation API
A Python plugin can interact with the user using the sudo.conv() function which displays one or more messages described by the sudo.ConvMessage class. This is the Python equivalent of the conversation() function in the C sudo plugin API. 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 sudo.ConvMessage class specifies how the user interaction should occur:

    sudo.ConvMessage(msg_type: int, msg: str, timeout: int)

sudo.ConvMessage member variables:

msg_type
    Specifies the type of the conversation. See the sudo.CONV.* constants below.

msg The message to display to the user. The caller must include a trailing newline in msg if one is to be displayed.

timeout
    Optional. The maximum amount of time for the conversation in seconds. If the timeout is exceeded, the sudo.conv() function will raise a sudo.ConversationInterrupted exception. The default is to wait forever (no timeout).

To specify the message type, the following constants are available:

•   sudo.CONV.PROMPT_ECHO_OFF
•   sudo.CONV.PROMPT_ECHO_ON
•   sudo.CONV.ERROR_MSG
•   sudo.CONV.INFO_MSG
•   sudo.CONV.PROMPT_MASK
•   sudo.CONV.PROMPT_ECHO_OK
•   sudo.CONV.PREFER_TTY

See the sudo_plugin(5) manual for a description of the message types.

The sudo.conv() function performs the actual user interaction:

    sudo.conv(message(s), on_suspend=suspend_function,
        on_resume=resume_function)

The function arguments are as follows:

message(s)
    One of more messages (of type sudo.ConvMessage), each describing a conversation. At least one message is required.

on_suspend
    An optional callback function which gets called if the conversation is suspended, for example by the user pressing control-Z. The specified function must take a single argument which will be filled with the number of the signal that caused the process to be suspended.

on_resume
    An optional callback function which gets called when the previously suspended conversation is resumed. The specified function must take a single argument which will be filled with the number of the signal that caused the process to be suspended.

The sudo.conv() function can raise the following exceptions:

sudo.SudoException
    If the conversation fails, for example when the conversation function is not available.

sudo.ConversationInterrupted
    If the conversation function returns an error, e.g., the timeout passed or the user interrupted the conversation by pressing control-C.

  Conversation example
Sudo ships with an example plugin demonstrating the Python conversation API. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_io python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_conversation.py \
        ClassName=ReasonLoggerIOPlugin

  Information / error display API

    sudo.log_info(string(s), sep=" ", end="\n")
    sudo.log_error(string(s), sep=" ", end="\n")

To display information to the user, the sudo.log_info() function can be used. To display error messages, use sudo.log_error(). The syntax is similar to the Python print() function.

The function arguments are as follows:

string(s)
    One or more strings to display.

sep An optional string which will be used as the separator between the specified strings. The default is a space character, (‘ ’).

end An optional string which will be displayed at the end of the message. The default is a new line character (‘\n’).

  Debug API
Debug messages are not visible to the user and are only logged debugging is explicitly enabled in sudo.conf(5). Python plugins can use the sudo.debug() function to make use of sudo's debug system.

Enabling debugging in sudo.conf

To enable debug messages, add a Debug line to sudo.conf(5) with the program set to python_plugin.so. For example, to store debug output in /var/log/sudo_python_debug, use a line like the following:

    Debug python_plugin.so /var/log/sudo_python_debug \
        plugin@trace,c_calls@trace

The debug options are in the form of multiple “subsystem@level” strings, separated by commas (‘’),. For example to just see the debug output of sudo.debug() calls, use:

    Debug python_plugin.so /var/log/sudo_python_debug plugin@trace

See sudo_conf(5) for more details.

The most interesting subsystems for Python plugin development are:

plugin
    Logs each sudo.debug() API call.

py_calls
    Logs whenever a C function calls into the python module. For example, calling the __init__() function.

c_calls
    Logs whenever python calls into a C sudo API function.

internal
    Logs internal functions of the python language wrapper plugin.

sudo_cb
    Logs when sudo calls into the python plugin API.

load
    Logs python plugin loading / unloading events.

You can also specify “all” as the subsystem name to log debug messages for all subsystems.

The sudo.debug() function is defined as:

    sudo.debug(level, message(s))

The function arguments are as follows:

level
    an integer, use one of the log level constants below

message(s)
    one or more messages to log

Available log levels:
sudo.conf name | Python constant | description
crit | sudo.DEBUG.CRIT | critical errors
err | sudo.DEBUG.ERROR | non-critical errors
warn | sudo.DEBUG.WARN | non-fatal warnings
notice | sudo.DEBUG.NOTICE | non-error condition notices
diag | sudo.DEBUG.DIAG | diagnostic messages
info | sudo.DEBUG.INFO | informational message
trace | sudo.DEBUG.TRACE | log function enter/exit
debug | sudo.DEBUG.DEBUG | very verbose debugging

Using the logging module

Alternatively, a plugin can use the built in logging module of Python as well. Sudo adds its log handler to the root logger, so by default all output of a logger will get forwarded to sudo log system, as it would call sudo.debug.

The log handler of sudo will map each Python log level of a message to the appropriate sudo debug level. The sudo debug system will only receive messages that are not filtered out by the Python loggers. For example, the log level of the python logger will be an additional filter for the log messages, and is usually very different from what level is set in sudo.conf for the sudo debug system.

  Debug example
Sudo ships with an example debug plugin. To try it, register it by adding the following lines to /etc/sudo.conf:

    Plugin python_io python_plugin.so \
        ModulePath=/usr/share/doc/sudo/examples/example_debugging.py \
        ClassName=DebugDemoPlugin
    Debug python_plugin.so \
        /var/log/sudo_python_debug plugin@trace,c_calls@trace

  Option conversion API
The Python plugin API includes two convenience functions to convert options in “key=value” format to a dictionary and vice versa.

options_as_dict
        options_as_dict(options)

    The function arguments are as follows:

    options
        An iterable (tuple, list, etc.) of strings, each in “key=value” format. This is how the plugin API passes options and settings to a Python plugin.

    The function returns the resulting dictionary. Each string of the passed in options will be split at the first equal sign (‘=’) into a key and value. Dictionary keys will never contain this symbol (but values may).

options_from_dict
        options_from_dict(options_dict)

    The function arguments are as follows:

    options_dict
        A dictionary where both the key and the value are strings. The key should not contain an equal sign (‘=’), otherwise the resulting string will have a different meaning. However, this is not currently enforced.

    The function returns a tuple containing the strings in “key=value” form for each key and value in the options_dict dictionary passed in. This is how the plugin API accepts options and settings.

PLUGIN API CHANGELOG (Python)
None yet

LIMITATIONS
A maximum of 8 python I/O plugins can be loaded at once. If /etc/sudo.conf contains more, those will be rejected with a warning message.

The Event API and the hook function API is currently not accessible for Python plugins.

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

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

Todd C. Miller

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

BUGS
Python plugin support is currently considered experimental.

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

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

SECURITY CONSIDERATIONS
All Python plugin handling is implemented inside the python_plugin.so dynamic plugin. Therefore, if no Python plugin is registered in sudo.conf(5) or the sudoers file, sudo will not load the Python interpreter or the Python libraries.

As sudo runs plugins as root, care must be taken when writing Python plugins to avoid creating security vulnerabilities, just as one would when writing plugins in C.

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