Linux command sudo

Starting with version 1.8,

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

binary itself. By default, the

policy plugin and an associated I/O logging plugin are used. Via the plugin API,

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

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

header file.

A policy plugin must declare and populate a

struct in the global scope. This structure contains pointers to the functions that implement the

policy checks. The name of the symbol should be specified in

along with a path to the plugin so that

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[], const char **errstr); 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[], const char **errstr); int (*list)(int argc, char * const argv[], int verbose, const char *list_user, const char **errstr); int (*validate)(const char **errstr); void (*invalidate)(int remove); int (*init_session)(struct passwd *pwd, char **user_env[], const char **errstr); void (*register_hooks)(int version, int (*register_hook)(struct sudo_hook *hook)); void (*deregister_hooks)(int version, int (*deregister_hook)(struct sudo_hook *hook)); struct sudo_plugin_event * (*event_alloc)(void); };

The policy_plugin struct has the following fields:

The

field should always be set to SUDO_POLICY_PLUGIN.

The

field should be set to

This allows

to determine the API version the plugin was built against.

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[], const char **errstr);

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,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

The version passed in by

allows the plugin to determine the major and minor version number of the plugin API supported by

A pointer to the

function that can be used by the plugin to interact with the user (see

for details). Returns 0 on success and -1 on failure.

A pointer to a

function that may be used to display informational or error messages (see

for details). Returns the number of characters printed on success and -1 on failure.

A vector of user-supplied

settings in the form of

strings. The vector is terminated by a

pointer. These settings correspond to options the user specified when running

As such, they will only be present when the corresponding option has been specified on the command line.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

The following values may be set by

Authentication type, if specified by the

option, to use on systems where

authentication is supported.

If specified, the user has requested via the

option that

close all files descriptors with a value of

or higher. The plugin may optionally pass this, or another value, back in the

list.

The root directory (see

to run the command in, as specified by the user via the

option. The plugin may ignore or restrict the user's ability to specify a new root directory. Only available starting with API version 1.16.

The working directory to run the command in, as specified by the user via the

option. The plugin may ignore or restrict the user's ability to specify a new working directory. Only available starting with API version 1.16.

A debug file path name followed by a space and a comma-separated list of debug flags that correspond to the plugin's

entry in

if there is one. The flags are passed to the plugin exactly as they appear in

The syntax used by

and the

plugin is

but a plugin is free to use a different format so long as it does not include a comma

Prior to

1.8.12, there was no way to specify plugin-specific

so the value was always the same as that used by the

front end and did not include a path name, only the flags themselves. As of version 1.7 of the plugin interface,

will only pass

contains a plugin-specific

entry.

Set to true if the user specified the

option along with a command, indicating that the user wishes to ignore any cached authentication credentials.

to true. This allows

with no arguments to be used similarly to

If the plugin does not to support this usage, it may return a value of -2 from the

function, which will cause

to print a usage message and exit.

If the user does not specify a program on the command line,

will pass the plugin the path to the user's shell and set

option.

Set to true if the user specified the

option, indicating that the user wishes to run a login shell.

The maximum number of groups a user may belong to. This will only be present if there is a corresponding setting in

A space-separated list of IP network addresses and netmasks in the form

e.g.,

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.

Set to true if the user specified the

option, indicating that

should operate in non-interactive mode. The plugin may reject a command run in non-interactive mode if user interaction is required.

The default plugin directory used by the

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.

The path name of plugin loaded by the

front end. The path name will be a fully-qualified unless the plugin was statically compiled into

Set to true if the user specified the

option, indicating that the user wishes to preserve the environment.

Set to true if the user specified the

option, indicating that the user wishes to preserve the group vector instead of setting it based on the runas user.

The command name that sudo was run as, typically

The prompt to use when requesting a password, if specified via the

option.

The name of the remote host to run the command on, if specified via the

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

front end is only capable of executing commands on the local host. Only available starting with API version 1.4.

Set to true if the user specified the

option, indicating that the user wishes to run a shell.

The group name or gid to run the command as, if specified via the

option.

The user name or uid to run the command as, if specified via the

option.

SELinux role to use when executing the command, if specified by the

option.

SELinux type to use when executing the command, if specified by the

option.

Set to true if the user specified the

option. If true, set the

environment variable to the target user's home directory.

Set to true when the

option is specified or if invoked as

The plugin shall substitute an editor into

in the

function or return -2 with a usage error if the plugin does not support

For more information, see the

section.

Command timeout specified by the user via the

option. Not all plugins support command timeouts and the ability of the user to set a timeout may be restricted by policy. The format of the timeout string is plugin-specific.

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

A vector of information about the user running the command in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

The following values may be set by

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

The user's current working directory.

The effective group-ID of the user invoking

The effective user-ID of the user invoking

The real group-ID of the user invoking

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

The local machine's hostname as returned by the

system call.

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

The ID of the process group that the running

process is a member of. Only available starting with API version 1.2.

The process ID of the running

process. Only available starting with API version 1.2.

The parent process ID of the running

process. Only available starting with API version 1.2.

The maximum size to which the process's address space may grow (in bytes), if supported by the operating system. The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The largest size core dump file that may be created (in bytes). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum amount of CPU time that the process may use (in seconds). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum size of the data segment for the process (in bytes). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The largest size file that the process may create (in bytes). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum number of locks that the process may establish, if supported by the operating system. The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum size that the process may lock in memory (in bytes), if supported by the operating system. The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum number of files that the process may have open. The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum number of processes that the user may run simultaneously. The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum size to which the process's resident set size may grow (in bytes). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The maximum size to which the process's stack may grow (in bytes). The soft and hard limits are separated by a comma. A value of

indicates that there is no limit. Only available starting with API version 1.16.

The session ID of the running

process or 0 if

is not part of a POSIX job control session. Only available starting with API version 1.2.

The ID of the foreground process group associated with the terminal device associated with the

process or 0 if there is no terminal present. Only available starting with API version 1.2.

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

The real user-ID of the user invoking

The invoking user's file creation mask. Only available starting with API version 1.10.

The name of the user invoking

The user's environment in the form of a

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

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

array of strings. If no arguments were specified,

will be the

pointer.

NOTE: the

parameter is only available starting with API version 1.2. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

function is called when

is finished, shortly before it exits. Starting with API version 1.15,

is called regardless of whether or not a command was actually executed. This makes it possible for plugins to perform cleanup even when a command was not run. It is not possible to tell whether a command was run based solely on the arguments passed to the

function. To determine if a command was actually run, the plugin must keep track of whether or not the

function returned successfully.

The function arguments are as follows:

The command's exit status, as returned by the

system call, or zero if no command was run. The value of

is undefined if

is non-zero.

If the command could not be executed, this is set to the value of

set by the

system call. The plugin is responsible for displaying error information via the

function. If the command was successfully executed, the value of

is zero.

If no

function is defined, no I/O logging plugins are loaded, and neither the

not

options are set in the

list, the

front end may execute the command directly instead of running it as a child process.

int (*show_version)(int verbose);

The

function is called by

when the user specifies the

option. The plugin may display its version information to the user via the

function using

If the user requests detailed version information, the verbose flag will be set.

Returns 1 on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error, although the return value is currently ignored.

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

The

function is called by

to determine whether the user is allowed to run the specified commands.

If the

option was enabled in the

array passed to the

function, the user has requested

mode.

is a mechanism for editing one or more files where an editor is run with the user's credentials instead of with elevated privileges.

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

it should choose the editor to be used, potentially from a variable in the user's environment, such as

and include it in

(note that environment variables may include command line options). The files to be edited should be copied from

into

separated from the editor and its arguments by a

element. The

will be removed by

before the editor is executed. The plugin should also set

in the

list.

The

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

was specified but is unsupported by the plugin. In the latter case,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

The number of elements in

not counting the final

pointer.

The argument vector describing the command the user wishes to run, in the same form as what would be passed to the

system call. The vector is terminated by a

pointer.

Additional environment variables specified by the user on the command line in the form of a

vector of

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

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

Information about the command being run in the form of

strings. These values are used by

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

pointer. The following values are recognized by

The root directory to use when running the command.

If specified,

will close all files descriptors with a value of

or higher.

Fully qualified path to the command to be executed.

The current working directory to change to when executing the command. If

is unable to change to the new working directory, the command will not be run unless

is also set (see below).

If enabled,

will treat an inability to change to the new working directory as a non-fatal error. This setting has no effect unless

is also set.

By default,

runs a command as the foreground process as long as

itself is running in the foreground. When

is enabled and the command is being run in a pseudo-terminal (due to I/O logging or the

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

signal (or

in the case of terminal settings). If this happens when

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

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

behavior or when the command is not being run in a pseudo-terminal.

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, macOS fails to restart the

and

system calls (this is a bug in macOS). Furthermore, because this behavior depends on the command stopping with the

signals, programs that catch these signals and suspend themselves with a different signal (usually

will not be automatically foregrounded. Some versions of the linux

command behave this way. Because of this, a plugin should not set

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

is enabled.

If specified,

will use the

system call to execute the command instead of

The specified

must refer to an open file descriptor.

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.

The group that will own newly created I/O log files and directories. This is a hint to the I/O logging plugin which may choose to ignore it.

The file permission mode to use when creating I/O log files and directories. This is a hint to the I/O logging plugin which may choose to ignore it.

The user that will own newly created I/O log files and directories. This is a hint to the I/O logging plugin which may choose to ignore it.

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.

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.

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.

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.

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.

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

Nice value (priority) to use when executing the command. The nice value, if specified, overrides the priority associated with the

systems.

If set, prevent the command from executing other programs.

A comma-separated list of file descriptors that should be preserved, regardless of the value of the

setting. Only available starting with API version 1.5.

If set,

will preserve the user's group vector instead of initializing the group vector based on

Effective group-ID to run the command as. If not specified, the value of

is used.

Effective user-ID to run the command as. If not specified, the value of

is used.

Group-ID to run the command as.

The name of the group the command will run as, if it is different from the

default group. This value is provided for auditing purposes only, the

front-end uses

and

when executing the command.

The supplementary group vector to use for the command in the form of a comma-separated list of group-IDs. If

is set, this option is ignored.

User-ID to run the command as.

The name of the user the command will run as, which should correspond to

(or

is not set). This value is provided for auditing purposes only, the

front-end uses

and

when executing the command.

SELinux role to use when executing the command.

SELinux type to use when executing the command.

Create a utmp (or utmpx) entry when a pseudo-terminal 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.

Set to true when in

mode. The plugin may enable

mode even if

was not invoked as

This allows the plugin to perform command substitution and transparently enable

when the user attempts to run an editor.

Set to false to disable directory writability checks in

By default,

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

will refuse to edit a file located in a writable directory. These restrictions are not enforced when

is run by root. The

option can be set to false to disable this check. Only available starting with API version 1.8.

Set to true to allow

to edit files that are symbolic links. By default,

1.8.15 and higher will refuse to open a symbolic link. The

option can be used to restore the older behavior and allow

to open symbolic links. Only available starting with API version 1.8.

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

The file creation mask to use when executing the command. This value may be overridden by PAM or login.conf on some systems unless the

option is also set.

Force the value specified by the

option to override any umask set by PAM or login.conf.

Allocate a pseudo-terminal to run the command in, regardless of whether or not I/O logging is in use. By default,

will only run the command in a pseudo-terminal when an I/O log plugin is loaded.

User name to use when constructing a new utmp (or utmpx) entry when

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,

will base the new entry on the invoking user's existing entry.

Unsupported values will be ignored.

The

argument vector to pass to the

system call when executing the command. The plugin is responsible for allocating and populating the vector.

The

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

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

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

function with

to present additional error information to the user.

Privileges should be output via the

function using

The function arguments are as follows:

The number of elements in

not counting the final

pointer.

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

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.

Flag indicating whether to list in verbose mode or not.

The name of a different user to list privileges for if the policy allows it. If

the plugin should list the privileges of the invoking user.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

int (*validate)(const char **errstr);

The

function is called when

is run with the

option. For policy plugins such as

that cache authentication credentials, this function will validate and cache the credentials.

The

function should be

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

function with

to present additional error information to the user.

The function arguments are as follows:

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

void (*invalidate)(int remove);

The

function is called when

is run with the

option. For policy plugins such as

that cache authentication credentials, this function will invalidate the credentials. If the

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

The

function should be

if the plugin does not support credential caching.

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

The

function is called before

sets up the execution environment for the command. It is run in the parent

process and before any uid or gid changes. This can be used to perform session setup that is not supported by

such as opening the PAM session. The

function can be used to tear down the session that was opened by

The

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

The

argument points to the environment the command will run in, in the form of a

vector of

strings. This is the same string passed back to the front end via the Policy Plugin's

parameter. If the

function needs to modify the user environment, it should update the pointer stored in

The expected use case is to merge the contents of the PAM environment (if any) with the contents of

NOTE: the

parameter is only available starting with API version 1.2. A plugin

check the API version specified by the

front end before using

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

function with

to present additional error information to the user.

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

The

function is called by the sudo front end to register any hooks the plugin needs. If the plugin does not support hooks,

should be set to the

pointer.

The

argument describes the version of the hooks API supported by the

front end.

The

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

does not match the front end's major hook API version.

See the

section below for more information about hooks.

NOTE: the

function is only available starting with API version 1.2. If the

front end doesn't support API version 1.2 or higher,

will not be called.

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

The

function is called by the sudo front end to deregister any hooks the plugin has registered. If the plugin does not support hooks,

should be set to the

pointer.

The

argument describes the version of the hooks API supported by the

front end.

The

function should be used to deregister any hooks that were put in place by the

function. If the plugin tries to deregister a hook that the front end does not support,

will return an error.

See the

section below for more information about hooks.

NOTE: the

function is only available starting with API version 1.2. If the

front end doesn't support API version 1.2 or higher,

will not be called.

struct sudo_plugin_event * (*event_alloc)(void);

The

function is used to allocate a

which provides access to the main

event loop. Unlike the other fields, the

pointer is filled in by the

front end, not by the plugin.

See the

section below for more information about events.

NOTE: the

function is only available starting with API version 1.15. If the

front end doesn't support API version 1.15 or higher,

will not be set.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

/* Plugin API version major/minor. */ #define SUDO_API_VERSION_MAJOR 1 #define SUDO_API_VERSION_MINOR 13 #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)

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[], const char **errstr); 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, const char **errstr); int (*log_ttyout)(const char *buf, unsigned int len, const char **errstr); int (*log_stdin)(const char *buf, unsigned int len, const char **errstr); int (*log_stdout)(const char *buf, unsigned int len, const char **errstr); int (*log_stderr)(const char *buf, unsigned int len, const char **errstr); void (*register_hooks)(int version, int (*register_hook)(struct sudo_hook *hook)); void (*deregister_hooks)(int version, int (*deregister_hook)(struct sudo_hook *hook)); int (*change_winsize)(unsigned int lines, unsigned int cols, const char **errstr); int (*log_suspend)(int signo, const char **errstr); struct sudo_plugin_event * (*event_alloc)(void); };

When an I/O plugin is loaded,

runs the command in a pseudo-terminal. 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,

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-terminal that is suitable for replaying the user's session at a later time. The

and

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

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

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 audit_plugin struct has the following fields:

The

field should always be set to

The

field should be set to

This allows

to determine the API version the plugin was built against.

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[]);

The

function is run before the

functions are called. It is only called if the version is being requested or if the policy plugin's

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,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

The version passed in by

allows the plugin to determine the major and minor version number of the plugin API supported by

A pointer to the

function that may be used by the

function to display version information (see

below). The

function may also be used to display additional error message to the user. The

function returns 0 on success and -1 on failure.

A pointer to a

function that may be used by the

function to display version information (see show_version below). The

function may also be used to display additional error message to the user. The

function returns number of characters printed on success and -1 on failure.

A vector of user-supplied

settings in the form of

strings. The vector is terminated by a

pointer. These settings correspond to options the user specified when running

As such, they will only be present when the corresponding option has been specified on the command line.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible settings.

A vector of information about the user running the command in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

A vector of information describing the command being run in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

The number of elements in

not counting the final

pointer. It can be zero, when

is called with

an argument vector describing a command the user wishes to run in the same form as what would be passed to the

system call.

The user's environment in the form of a

vector of

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

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

array of strings. If no arguments were specified,

will be the

pointer.

NOTE: the

parameter is only available starting with API version 1.2. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

function is called when

is finished, shortly before it exits.

The function arguments are as follows:

The command's exit status, as returned by the

system call, or zero if no command was run. The value of

is undefined if

is non-zero.

If the command could not be executed, this is set to the value of

set by the

system call. If the command was successfully executed, the value of

is zero.

int (*show_version)(int verbose);

The

function is called by

when the user specifies the

option. The plugin may display its version information to the user via the

function using

Returns 1 on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error, although the return value is currently ignored.

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

The

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:

The buffer containing user input.

The length of

in bytes.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

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:

The buffer containing command output.

The length of

in bytes.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

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:

The buffer containing user input.

The length of

in bytes.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

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:

The buffer containing command output.

The length of

in bytes.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

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

The

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:

The buffer containing command output.

The length of

in bytes.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

See the

section for a description of

See the

section for a description of

int (*change_winsize)(unsigned int lines, unsigned int cols, const char **errstr);

The

function is called whenever the window size of the terminal changes from the initial values specified in the

list. Returns -1 if an error occurred, in which case no further calls to

will be made,

The function arguments are as follows:

The number of lines (rows) in the re-sized terminal.

The number of columns in the re-sized terminal.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

int (*log_suspend)(int signo, const char **errstr);

The

function is called whenever a command is suspended or resumed. Logging this information makes it possible to skip the period of time when the command was suspended during playback of a session. Returns -1 if an error occurred, in which case no further calls to

will be made,

The function arguments are as follows:

The signal that caused the command to be suspended, or

if the command was resumed.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

NOTE: the

parameter is only available starting with API version 1.15. A plugin

check the API version specified by the

front end before using

Failure to do so may result in a crash.

struct sudo_plugin_event * (*event_alloc)(void);

The

function is used to allocate a

which provides access to the main

event loop. Unlike the other fields, the

pointer is filled in by the

front end, not by the plugin.

See the

section below for more information about events.

NOTE: the

function is only available starting with API version 1.15. If the

front end doesn't support API version 1.15 or higher,

will not be set.

Same as for the

/* Audit plugin close function status types. */ #define SUDO_PLUGIN_NO_STATUS 0 #define SUDO_PLUGIN_WAIT_STATUS 1 #define SUDO_PLUGIN_EXEC_ERROR 2 #define SUDO_PLUGIN_SUDO_ERROR 3

#define SUDO_AUDIT_PLUGIN 3 struct audit_plugin { unsigned int type; /* always SUDO_AUDIT_PLUGIN */ unsigned int version; /* always SUDO_API_VERSION */ int (*open)(unsigned int version, sudo_conv_t conversation, sudo_printf_t sudo_printf, char * const settings[], char * const user_info[], int submit_optind, char * const submit_argv[], char * const submit_envp[], char * const plugin_options[], const char **errstr); void (*close)(int status_type, int status); int (*accept)(const char *plugin_name, unsigned int plugin_type, char * const command_info[], char * const run_argv[], char * const run_envp[], const char **errstr); int (*reject)(const char *plugin_name, unsigned int plugin_type, const char *audit_msg, char * const command_info[], const char **errstr); int (*error)(const char *plugin_name, unsigned int plugin_type, const char *audit_msg, char * const command_info[], const char **errstr); int (*show_version)(int verbose); void (*register_hooks)(int version, int (*register_hook)(struct sudo_hook *hook)); void (*deregister_hooks)(int version, int (*deregister_hook)(struct sudo_hook *hook)); struct sudo_plugin_event * (*event_alloc)(void); }

An audit plugin can be used to log successful and unsuccessful attempts to run

independent of the policy or any I/O plugins. Multiple audit plugins may be specified in

The audit_plugin struct has the following fields:

The

field should always be set to

The

field should be set to

This allows

to determine the API version the plugin was built against.

int (*open)(unsigned int version, sudo_conv_t conversation, sudo_printf_t sudo_printf, char * const settings[], char * const user_info[], int submit_optind, char * const submit_argv[], char * const submit_envp[], char * const plugin_options[], const char **errstr);

The audit

function is run before any other

plugin API functions. This makes it possible to audit failures in the other plugins. 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,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

The version passed in by

allows the plugin to determine the major and minor version number of the plugin API supported by

A pointer to the

function that may be used by the

function to display version information (see

below). The

function may also be used to display additional error message to the user. The

function returns 0 on success and -1 on failure.

A pointer to a

function that may be used by the

function to display version information (see show_version below). The

function may also be used to display additional error message to the user. The

function returns number of characters printed on success and -1 on failure.

A vector of user-supplied

settings in the form of

strings. The vector is terminated by a

pointer. These settings correspond to options the user specified when running

As such, they will only be present when the corresponding option has been specified on the command line.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible settings.

A vector of information about the user running the command in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

The index into

that corresponds to the first entry that is not a command line option. If

only consists of options, which may be the case with the

options,

will evaluate to the NULL pointer.

The argument vector

was invoked with, including all command line options. The

argument can be used to determine the end of the command line options.

The invoking user's environment in the form of a

vector of

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

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

array of strings. If no arguments were specified,

will be the

pointer.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

void (*close)(int status_type, int status);

The

function is called when

is finished, shortly before it exits.

The function arguments are as follows:

The type of status being passed. One of

Depending on the value of

this value is either ignored, the command's exit status as returned by the

system call, the value of

set by the

system call, or the value of

resulting from an error in the

front end.

int (*accept)(const char *plugin_name, unsigned int plugin_type, char * const command_info[], char * const run_argv[], char * const run_envp[], const char **errstr);

The

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

The name of the plugin that accepted the command or

for the

front-end.

The type of plugin that accepted the command, currently either

The

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,

may include information from an I/O logging plugin as well.

Typically, an audit plugin is interested in either the accept status from the

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

and

functions will

be called.

An optional vector of information describing the command being run in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

argument vector describing a command that will be run in the same form as what would be passed to the

system call.

The environment the command will be run with in the form of a

vector of

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

int (*reject)(const char *plugin_name, unsigned int plugin_type, const char *audit_msg, char * const command_info[], const char **errstr);

The

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

The name of the plugin that rejected the command.

The type of plugin that rejected the command, currently either

Unlike the

function, the

function is not called on behalf of the

front-end.

An optional string describing the reason the command was rejected by the plugin. If the plugin did not provide a reason,

will be the

pointer.

An optional vector of information describing the command being run in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

int (*error)(const char *plugin_name, unsigned int plugin_type, const char *audit_msg, char * const command_info[], const char **errstr);

The

function is called when a plugin or the

front-end returns an error. The function arguments are as follows:

The name of the plugin that generated the error or

for the

front-end.

The type of plugin that generated the error, or

for the

front-end.

An optional string describing the plugin error. If the plugin did not provide a description,

will be the

pointer.

An optional vector of information describing the command being run in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

int (*show_version)(int verbose);

The

function is called by

when the user specifies the

option. The plugin may display its version information to the user via the

function using

If the user requests detailed version information, the verbose flag will be set.

Returns 1 on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error, although the return value is currently ignored.

See the

section for a description of

See the

section for a description of

struct sudo_plugin_event * (*event_alloc)(void);

The

function is used to allocate a

which provides access to the main

event loop. Unlike the other fields, the

pointer is filled in by the

front end, not by the plugin.

See the

section below for more information about events.

NOTE: the

function is only available starting with API version 1.17. If the

front end doesn't support API version 1.17 or higher,

will not be set.

struct approval_plugin { #define SUDO_APPROVAL_PLUGIN 4 unsigned int type; /* always SUDO_APPROVAL_PLUGIN */ unsigned int version; /* always SUDO_API_VERSION */ int (*open)(unsigned int version, sudo_conv_t conversation, sudo_printf_t sudo_printf, char * const settings[], char * const user_info[], int submit_optind, char * const submit_argv[], char * const submit_envp[], char * const plugin_options[], const char **errstr); void (*close)(void); int (*check)(char * const command_info[], char * const run_argv[], char * const run_envp[], const char **errstr); int (*show_version)(int verbose); };

An approval plugin can be used to apply extra constraints after a command has been accepted by the policy plugin. Unlike the other plugin types, it does not remain open until the command completes. The plugin is opened before a call to

and closed shortly thereafter (audit plugin functions must be called before the plugin is closed). Multiple approval plugins may be specified in

The approval_plugin struct has the following fields:

The

field should always be set to

The

field should be set to

This allows

to determine the API version the plugin was built against.

The approval

function is run immediately before a call to the plugin's

functions. It is only called if the version is being requested or if the policy plugin's

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,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

The version passed in by

allows the plugin to determine the major and minor version number of the plugin API supported by

A pointer to the

function that can be used by the plugin to interact with the user (see

for details). Returns 0 on success and -1 on failure.

A pointer to a

function that may be used to display informational or error messages (see

for details). Returns the number of characters printed on success and -1 on failure.

A vector of user-supplied

settings in the form of

strings. The vector is terminated by a

pointer. These settings correspond to options the user specified when running

As such, they will only be present when the corresponding option has been specified on the command line.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible settings.

A vector of information about the user running the command in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

The index into

that corresponds to the first entry that is not a command line option. If

only consists of options, which may be the case with the

options,

will evaluate to the NULL pointer.

The argument vector

was invoked with, including all command line options. The

argument can be used to determine the end of the command line options.

The invoking user's environment in the form of a

vector of

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

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

array of strings. If no arguments were specified,

will be the

pointer.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

void (*close)(void);

The

function is called after the approval plugin's

functions have been called. It takes no arguments. The

function is typically used to perform plugin-specific cleanup, such as the freeing of memory objects allocated by the plugin. If the plugin does not need to perform any cleanup,

may be set to the

pointer.

int (*check)(char * const command_info[], char * const run_argv[], char * const run_envp[], const char **errstr);

The approval

function is run after the policy plugin

function and before any I/O logging plugins. If multiple approval plugins are loaded, they must all succeed for the command to be allowed. 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,

will print a usage message before it exits. If an error occurs, the plugin may optionally call the

function with

to present additional error information to the user.

The function arguments are as follows:

A vector of information describing the command being run in the form of

strings. The vector is terminated by a

pointer.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

See the

section for a list of all possible strings.

argument vector describing a command that will be run in the same form as what would be passed to the

system call.

The environment the command will be run with in the form of a

vector of

strings.

When parsing

the plugin should split on the

equal sign

since the

field will never include one itself but the

might.

If the

function returns a value other than 1, the plugin may store a message describing the failure or error in

The

front end will then pass this value to any registered audit plugins. The string stored in

must remain valid until the plugin's

function is called.

int (*show_version)(int verbose);

The

function is called by

when the user specifies the

option. The plugin may display its version information to the user via the

function using

If the user requests detailed version information, the verbose flag will be set.

Returns 1 on success, 0 on failure, -1 if a general error occurred, or -2 if there was a usage error, although the return value is currently ignored.

The

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:

If a fatal signal is received before the command is executed,

will call the plugin's

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

function. An exception to this is

which is ignored until the command is executed.

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

Beginning with plugin API version 1.2, it is possible to install hooks for certain functions called by the

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

front end functions as well.

Hooks in

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

structure has the following fields:

The

field should be set to

The

field may be one of the following supported hook types:

The C library

function. Any registered hooks will run before the C library implementation. The

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.

The C library

function. Any registered hooks will run before the C library implementation. The

field should be a function that matches the following typedef:

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

The C library

function. Any registered hooks will run before the C library implementation. The

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.

The C library

function. Any registered hooks will run before the C library implementation. The

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.

sudo_hook_fn_t hook_fn;

The

field should be set to the plugin's hook implementation. The actual function arguments will vary depending on the

(see

above). In all cases, the

field of

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:

The hook function encountered an error.

The hook completed without error, go on to the next hook (including the system implementation if applicable). For example, a

hook might return

if the specified variable was not found in the private copy of the environment.

The hook completed without error, stop processing hooks for this invocation. This can be used to replace the system implementation. For example, a

hook that operates on a private copy of the environment but leaves

unchanged.

Note that it is very easy to create an infinite loop when hooking C library functions. For example, a

hook that calls the

function may create a loop if the

implementation calls

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 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

When

runs a command, it uses an event loop to service signals and I/O. Events may be triggered based on time, a file or socket descriptor becoming ready, or due to receipt of a signal. Starting with API version 1.15, it is possible for a plugin to participate in this event loop by calling the

function.

Events are described by the following structure:

typedef void (*sudo_plugin_ev_callback_t)(int fd, int what, void *closure);

struct sudo_plugin_event { int (*set)(struct sudo_plugin_event *pev, int fd, int events, sudo_plugin_ev_callback_t callback, void *closure); int (*add)(struct sudo_plugin_event *pev, struct timespec *timeout); int (*del)(struct sudo_plugin_event *pev); int (*pending)(struct sudo_plugin_event *pev, int events, struct timespec *ts); int (*fd)(struct sudo_plugin_event *pev); void (*setbase)(struct sudo_plugin_event *pev, void *base); void (*loopbreak)(struct sudo_plugin_event *pev); void (*free)(struct sudo_plugin_event *pev); };

The sudo_plugin_event struct contains the following function pointers:

int (*set)(struct sudo_plugin_event *pev, int fd, int events, sudo_plugin_ev_callback_t callback, void *closure);

The

function takes the following arguments:

A pointer to the struct sudo_plugin_event itself.

The file or socket descriptor for I/O-based events or the signal number for signal events. For time-based events,

must be -1.

The following values determine what will trigger the event callback:

callback is run after the specified timeout expires

callback is run when the file descriptor is readable

callback is run when the file descriptor is writable

event is persistent and remains enabled until explicitly deleted

callback is run when the specified signal is received

The

flag may be ORed with any of the event types. It is also possible to OR

and

together to run the callback when a descriptor is ready to be either read from or written to. All other event values are mutually exclusive.

typedef void (*sudo_plugin_ev_callback_t)(int fd, int what, void *closure);

The function to call when an event is triggered. The

function is run with the following arguments:

The file or socket descriptor for I/O-based events or the signal number for signal events.

The event type that triggered that callback. For events that have multiple event types (for example

and

or have an associated timeout,

can be used to determine why the callback was run.

The generic pointer that was specified in the

function.

A generic pointer that will be passed to the callback function.

The

function returns 1 on success, and -1 if a error occurred.

int (*add)(struct sudo_plugin_event *pev, struct timespec *timeout);

The

function adds the event

event loop. The event must have previously been initialized via the

function. If the

argument is not NULL, it should specify a (relative) timeout after which the event will be triggered if the main event criteria has not been met. This is often used to implement an I/O timeout where the event will fire if a descriptor is not ready within a certain time period. If the event is already present in the event loop, its

will be adjusted to match the new value, if any.

The

function returns 1 on success, and -1 if a error occurred.

int (*del)(struct sudo_plugin_event *pev);

The

function deletes the event

from

event loop. Deleted events can be added back via the

function.

The

function returns 1 on success, and -1 if a error occurred.

int (*pending)(struct sudo_plugin_event *pev, int events, struct timespec *ts);

The

function can be used to determine whether one or more events is pending. The

argument specifies which events to check for. See the

function for a list of valid event types. If

is specified in

the event has an associated timeout and the

pointer is non-NULL, it will be filled in with the remaining time.

int (*fd)(struct sudo_plugin_event *pev);

The

function returns the descriptor or signal number associated with the event

void (*setbase)(struct sudo_plugin_event *pev, void *base);

The

function sets the underlying event

for

to the specified value. This can be used to move an event created via

to a new event loop allocated by sudo's event subsystem. If

event base is reset to the default value, which corresponds to

main event loop. Using this function requires linking the plugin with the sudo_util library. It is unlikely to be used outside of the

plugin.

void (*loopbreak)(struct sudo_plugin_event *pev);

The

function causes

event loop to exit immediately and the running command to be terminated.

void (*free)(struct sudo_plugin_event *pev);

The

function deletes the event

from the event loop and frees the memory associated with it.

The

front end does not support running remote commands. However, starting with

1.8.8, the

option may be used to specify a remote host that is passed to the policy plugin. A plugin may also accept a

in the form of

which will work with older versions of

It is anticipated that remote commands will be supported by executing a

program. The policy plugin should setup the execution environment such that the

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

to perform remote command execution. The helper program would be responsible for running

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

functionality must be handled by the policy plugin, not

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.

If the plugin needs to interact with the user, it may do so via the

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

if one is to be printed.

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.

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 */ #define SUDO_CONV_PREFER_TTY 0x2000 /* flag: use tty if possible */ int msg_type; int timeout; const char *msg; };

#define SUDO_CONV_REPL_MAX 1023

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

and

functions are passed in to the plugin's

function when the plugin is initialized. The following type definitions can be used in the declaration of the

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

function, the plugin must pass an array of

and

structures. There must be a

and

for each message in the conversation, that is, both arrays must have the same number of elements. Each

must have its

member initialized to

The

pointer, if not

should contain function pointers to be called when the

process is suspended and/or resumed during conversation input. The

and

functions are called with the signal that caused

to be suspended and the

pointer from the

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

must be set to one of the following values:

Prompt the user for input with echo disabled; this is generally used for passwords. The reply will be stored in the

array, and it will never be

Prompt the user for input with echo enabled. The reply will be stored in the

array, and it will never be

Display an error message. The message is written to the standard error unless the

flag is set, in which case it is written to the user's terminal if possible.

Display a message. The message is written to the standard output unless the

flag is set, in which case it is written to the user's terminal if possible.

Prompt the user for input but echo an asterisk character for each character read. The reply will be stored in the

array, and it will never be

This can be used to provide visual feedback to the user while reading sensitive information that should not be displayed.

In addition to the above values, the following flag bits may also be set:

Allow input to be read when echo cannot be disabled when the message type is

By default,

will refuse to read input if the echo cannot be disabled for those message types.

When displaying a message via

try to write the message to the user's terminal. If the terminal is unavailable, the standard error or standard output will be used, depending upon whether The user's terminal is always used when possible for input, this flag is only used for output.

was used.

The

in seconds until the prompt will wait for no more input. A zero value implies an infinite timeout.

The plugin is responsible for freeing the reply buffer located in each

if it is not

represents the maximum length of the reply buffer (not including the trailing NUL character). In practical terms, this is the longest password

will support.

The

function uses the same underlying mechanism as the

function but only supports

and

for the

parameter. It can be more convenient than using the

function if no user reply is needed and supports standard

escape sequences.

See the sample plugin for an example of the

function usage.

As of

1.9.0, the plugin

and

functions are called in the following order:

audit open

policy open

approval open

approval close

I/O log open

command runs

command exits

I/O log close

policy close

audit close

sudo exits

Prior to

1.9.0, the I/O log

function was called

the policy

function.

The

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

and

are detailed in

Third party group plugins include a QAS AD plugin available from Quest Software.

A group plugin must declare and populate a

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

struct has the following fields:

The

field should be set to GROUP_API_VERSION.

This allows

to determine the API version the group plugin was built against.

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

The

function is called after

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

function with

to present additional error information to the user.

The function arguments are as follows:

The version passed in by

allows the plugin to determine the major and minor version number of the group plugin API supported by

A pointer to a

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.

array of arguments generated from the

option in

If no arguments were given,

will be

void (*cleanup)();

The

function is called when

has finished its group checks. The plugin should free any memory it has allocated and close open file handles.

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

The

function is used to ask the group plugin whether

is a member of

The function arguments are as follows:

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

The name of the group being queried.

The password database entry for

if any. If

is not present in the password database,

will be

/* 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

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

Initial API version.

The I/O logging plugin's

function was modified to take the

list as an argument.

The Policy and I/O logging plugins'

functions are now passed a list of plugin parameters if any are specified in

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

The

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.

Support for the

entry has been added to the

list.

The

and

entries were added to the

list.

The

and

functions are now optional. Previously, a missing

function would result in a crash. If no policy plugin

function is defined, a default

function will be provided by the

front end that displays a warning if the command could not be executed.

The

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

The

entry was added to the

list.

The

entry was added to the

list.

The behavior when an I/O logging plugin returns an error

has changed. Previously, the

front end took no action when the

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.

The

entry was added to the

list.

The

entry now starts with a debug file path name and may occur multiple times if there are multiple plugin-specific Debug lines in the

The

and

entries were added to the

list. The default value of

was changed to true in sudo 1.8.16.

The sudo

function now takes a pointer to a

as its fourth argument. The

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.

The

entry was added to the

list.

The

entry was added to the

list. The

and

entries were added to the

list.

The

entry was added to the

list.

The

field was added to the io_plugin struct.

The

field was added to the io_plugin struct.

The

entry was added to the

list.

The

entry was added to the

list.

The

field was added to the policy_plugin and io_plugin structs.

The

argument was added to the policy and I/O plugin functions which the plugin function can use to return an error string. This string may be used by the audit plugin to report failure or error conditions set by the other plugins.

The

function is now is called regardless of whether or not a command was actually executed. This makes it possible for plugins to perform cleanup even when a command was not run.

has increased from 255 to 1023 bytes.

Support for audit and approval plugins was added.

Initial resource limit values were added to the

list.

The

and

enties were added to the

list.

The

field was added to the audit_plugin and approval_plugin structs.

Many people have worked on

over the years; this version consists of code written primarily by:

See the CONTRIBUTORS file in the

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

If you feel you have found a bug in

please submit a bug report at https://bugzilla.sudo.ws/

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.

is provided

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

or https://www.sudo.ws/license.html for complete details.