diff options
Diffstat (limited to 'docs/sudo_plugin.mdoc.in')
| -rw-r--r-- | docs/sudo_plugin.mdoc.in | 4895 |
1 files changed, 4895 insertions, 0 deletions
diff --git a/docs/sudo_plugin.mdoc.in b/docs/sudo_plugin.mdoc.in new file mode 100644 index 0000000..b6d3b93 --- /dev/null +++ b/docs/sudo_plugin.mdoc.in @@ -0,0 +1,4895 @@ +.\" +.\" SPDX-License-Identifier: ISC +.\" +.\" Copyright (c) 2009-2023 Todd C. Miller <Todd.Miller@sudo.ws> +.\" +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. +.\" +.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +.\" +.Dd January 18, 2023 +.Dt SUDO_PLUGIN @mansectform@ +.Os Sudo @PACKAGE_VERSION@ +.Sh NAME +.Nm sudo_plugin +.Nd Sudo Plugin API +.Sh DESCRIPTION +Starting with version 1.8, +.Nm sudo +supports a plugin API +for policy and session logging. +Plugins may be compiled as dynamic shared objects (the default on +systems that support them) or compiled statically into the +.Nm sudo +binary itself. +By default, the +.Nm sudoers +plugin provides audit, security policy and I/O logging capabilities. +Via the plugin API, +.Nm sudo +can be configured to use alternate plugins provided by third parties. +The plugins to be used are specified in the +.Xr sudo.conf @mansectform@ +file. +.Pp +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. +.Pp +The plugin API is defined by the +.In sudo_plugin.h +header file. +.Ss Policy plugin API +A policy plugin must declare and populate a +.Vt struct policy_plugin +in the global scope. +This structure contains pointers to the functions that implement the +.Nm sudo +policy checks. +The name of the symbol should be specified in +.Xr sudo.conf @mansectform@ +along with a path to the plugin so that +.Nm sudo +can load it. +.Bd -literal +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 sudo_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 *user, const char **errstr); + int (*validate)(const char **errstr); + void (*invalidate)(int rmcred); + 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); +}; +.Ed +.Pp +A +.Vt struct policy_plugin +has the following fields: +.Bl -tag -width 4n +.It Fa type +The +.Fa type +field should always be set to SUDO_POLICY_PLUGIN. +.It Fa version +The +.Fa version +field should be set to +.Dv SUDO_API_VERSION . +.Pp +This allows +.Nm sudo +to determine the API version the plugin was +built against. +.It Fa open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_plugin_printf, char * const settings[], + char * const user_info[], char * const user_env[], + char * const plugin_options[], const char **errstr); +.Ed +.Pp +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, +.Nm sudo +will print a usage message before it exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa version +The version passed in by +.Nm sudo +allows the plugin to determine the +major and minor version number of the plugin API supported by +.Nm sudo . +.It Fa conversation +A pointer to the +.Fn conversation +function that can be used by the plugin to interact with the user (see +.Sx Conversation API +for details). +Returns 0 on success and \-1 on failure. +.It Fa sudo_plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used to display informational or error messages (see +.Sx Conversation API +for details). +Returns the number of characters printed on success and \-1 on failure. +.It Fa settings +A vector of user-supplied +.Nm sudo +settings in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +These settings correspond to options the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding option has +been specified on the command line. +.Pp +When parsing +.Fa settings , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one itself but the +.Em value +might. +.Pp +The following values may be set by +.Nm sudo : +.Bl -tag -width 4n +.It bsdauth_type=string +Authentication type, if specified by the +.Fl a +option, to use on +systems where +.Bx +authentication is supported. +.It closefrom=number +If specified, the user has requested via the +.Fl C +option that +.Nm sudo +close all files descriptors with a value of +.Em number +or higher. +The plugin may optionally pass this, or another value, back in the +.Fa command_info +list. +.It cmnd_chroot=string +The root directory (see +.Xr chroot 2 ) +to run the command in, as specified by the user via the +.Fl R +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. +.It cmnd_cwd=string +The working directory to run the command in, as specified by the user via the +.Fl D +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. +.It debug_flags=string +A debug file path name followed by a space and a comma-separated +list of debug flags that correspond to the plugin's +.Em Debug +entry in +.Xr sudo.conf @mansectform@ , +if there is one. +The flags are passed to the plugin exactly as they appear in +.Xr sudo.conf @mansectform@ . +The syntax used by +.Nm sudo +and the +.Nm sudoers +plugin is +.Em subsystem Ns @ Ns Em priority +but a plugin is free to use a different +format so long as it does not include a comma +.Pq Ql ,\& . +Prior to +.Nm sudo +1.8.12, there was no way to specify plugin-specific +.Em debug_flags +so the value was always the same as that used by the +.Nm sudo +front-end and did not include a path name, only the flags themselves. +As of version 1.7 of the plugin interface, +.Nm sudo +will only pass +.Em debug_flags +if +.Xr sudo.conf @mansectform@ +contains a plugin-specific +.Em Debug +entry. +.It ignore_ticket=bool +Set to true if the user specified the +.Fl k +option along with a +command, indicating that the user wishes to ignore any cached +authentication credentials. +.Em implied_shell +to true. +This allows +.Nm sudo +with no arguments +to be used similarly to +.Xr su 1 . +If the plugin does not to support this usage, it may return a value of \-2 +from the +.Fn check_policy +function, which will cause +.Nm sudo +to print a usage message and exit. +.It implied_shell=bool +If the user does not specify a program on the command line, +.Nm sudo +will pass the plugin the path to the user's shell and set +.Em implied_shell . +.It intercept_ptrace=bool +Indicates whether or not the system supports intercept +mode using +.Xr ptrace 2 . +This is currently only true for Linux systems that support +.Xr seccomp 2 +filtering and the +.Dq trap +action. +Other systems will use a dynamic shared object to implement +intercept. +Only available starting with API version 1.19. +.It intercept_setid=bool +Indicates whether or not the system supports running set-user-ID +and set-group-ID binaries in intercept mode. +This is currently only true for Linux systems that support +.Xr seccomp 2 +filtering and the +.Dq trap +action. +On systems that use a dynamic shared object to implement +intercept, the dynamic linker (ld.so or the equivalent) +will disable preloading of shared objects when executing a +set-user-ID or set-group-ID binary. +This will disable intercept mode for that program and any other +programs that it executes. +The policy plugin may refuse to execute a set-user-ID or set-group-ID +binary in intercept mode to avoid this. +Only available starting with API version 1.19. +.It login_class=string +.Bx +login class to use when setting resource limits and nice value, +if specified by the +.Fl c +option. +.It login_shell=bool +Set to true if the user specified the +.Fl i +option, indicating that +the user wishes to run a login shell. +.It max_groups=int +The maximum number of groups a user may belong to. +This will only be present if there is a corresponding setting in +.Xr sudo.conf @mansectform@ . +.It network_addrs=list +A space-separated list of IP network addresses and netmasks in the +form +.Dq addr/netmask , +e.g., +.Dq 192.168.1.2/255.255.255.0 . +The address and netmask pairs may be either IPv4 or IPv6, depending on +what the operating system supports. +If the address contains a colon +.Pq Ql :\& , +it is an IPv6 address, else it is IPv4. +.It noninteractive=bool +Set to true if the user specified the +.Fl n +option, indicating that +.Nm sudo +should operate in non-interactive mode. +The plugin may reject a command run in non-interactive mode if user +interaction is required. +.It plugin_dir=string +The default plugin directory used by the +.Nm sudo +front-end. +This is the default directory set at compile time and may not +correspond to the directory the running plugin was loaded from. +It may be used by a plugin to locate support files. +.It plugin_path=string +The path name of plugin loaded by the +.Nm sudo +front-end. +The path name will be a fully-qualified unless the plugin was +statically compiled into +.Nm sudo . +.It preserve_environment=bool +Set to true if the user specified the +.Fl E +option, indicating that +the user wishes to preserve the environment. +.It preserve_groups=bool +Set to true if the user specified the +.Fl P +option, indicating that +the user wishes to preserve the group vector instead of setting it +based on the runas user. +.It progname=string +The command name that sudo was run as, typically +.Dq sudo +or +.Dq sudoedit . +.It prompt=string +The prompt to use when requesting a password, if specified via +the +.Fl p +option. +.It remote_host=string +The name of the remote host to run the command on, if specified via +the +.Fl h +option. +Support for running the command on a remote host is meant to be implemented +via a helper program that is executed in place of the user-specified command. +The +.Nm sudo +front-end is only capable of executing commands on the local host. +Only available starting with API version 1.4. +.It run_shell=bool +Set to true if the user specified the +.Fl s +option, indicating that the user wishes to run a shell. +.It runas_group=string +The group name or group-ID to run the command as, if specified via +the +.Fl g +option. +.It runas_user=string +The user name or user-ID to run the command as, if specified via the +.Fl u +option. +.It selinux_role=string +SELinux role to use when executing the command, if specified by +the +.Fl r +option. +.It selinux_type=string +SELinux type to use when executing the command, if specified by +the +.Fl t +option. +.It set_home=bool +Set to true if the user specified the +.Fl H +option. +If true, set the +.Ev HOME +environment variable to the target user's home directory. +.It sudoedit=bool +Set to true when the +.Fl e +option is specified or if invoked as +.Nm sudoedit . +The plugin shall substitute an editor into +.Fa argv +in the +.Fn check_policy +function or return \-2 with a usage error +if the plugin does not support +.Em sudoedit . +For more information, see the +.Fn check_policy +section. +.It timeout=string +Command timeout specified by the user via the +.Fl T +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. +.It update_ticket=bool +Set to false if the user specified the +.Fl N +option, indicating that the user wishes to avoid updating any cached +authentication credentials. +Only available starting with API version 1.20. +.El +.Pp +Additional settings may be added in the future so the plugin should +silently ignore settings that it does not recognize. +.It Fa user_info +A vector of information about the user running the command in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa user_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +The following values may be set by +.Nm sudo : +.Bl -tag -width 4n +.It cols=int +The number of columns the user's terminal supports. +If there is no terminal device available, a default value of 80 is used. +.It cwd=string +The user's current working directory. +.It egid=gid_t +The effective group-ID of the user invoking +.Nm sudo . +.It euid=uid_t +The effective user-ID of the user invoking +.Nm sudo . +.It gid=gid_t +The real group-ID of the user invoking +.Nm sudo . +.It groups=list +The user's supplementary group list formatted as a string of +comma-separated group-IDs. +.It host=string +The local machine's hostname as returned by the +.Xr gethostname 2 +system call. +.It lines=int +The number of lines the user's terminal supports. +If there is +no terminal device available, a default value of 24 is used. +.It pgid=int +The ID of the process group that the running +.Nm sudo +process is a member of. +Only available starting with API version 1.2. +.It pid=int +The process ID of the running +.Nm sudo +process. +Only available starting with API version 1.2. +.It ppid=int +The parent process ID of the running +.Nm sudo +process. +Only available starting with API version 1.2. +.It rlimit_as=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_core=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_cpu=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_data=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_fsize=soft,hard +The largest size file that the process may create (in bytes). +The soft and hard limits are separated by a comma. +A value of +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_locks=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_memlock=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_nofile=soft,hard +The maximum number of files that the process may have open. +The soft and hard limits are separated by a comma. +A value of +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_nproc=soft,hard +The maximum number of processes that the user may run simultaneously. +The soft and hard limits are separated by a comma. +A value of +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_rss=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It rlimit_stack=soft,hard +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 +.Dq infinity +indicates that there is no limit. +Only available starting with API version 1.16. +.It sid=int +The session ID of the running +.Nm sudo +process or 0 if +.Nm sudo +is not part of a POSIX job control session. +Only available starting with API version 1.2. +.It tcpgid=int +The ID of the foreground process group associated with the terminal +device associated with the +.Nm sudo +process or 0 if there is no terminal present. +Only available starting with API version 1.2. +.It tty=string +The path to the user's terminal device. +If the user has no terminal device associated with the session, +the value will be empty, as in +.Ql tty= . +.It uid=uid_t +The real user-ID of the user invoking +.Nm sudo . +.It umask=octal +The invoking user's file creation mask. +Only available starting with API version 1.10. +.It user=string +The name of the user invoking +.Nm sudo . +.El +.It Fa user_env +The user's environment in the form of a +.Dv NULL Ns -terminated vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa user_env , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa plugin_options +Any (non-comment) strings immediately after the plugin path are +passed as arguments to the plugin. +These arguments are split on a white space boundary and are passed to +the plugin in the form of a +.Dv NULL Ns -terminated +array of strings. +If no arguments were +specified, +.Fa plugin_options +will be the +.Dv NULL +pointer. +.Pp +The +.Fa plugin_options +parameter is only available starting with +API version 1.2. +A plugin +.Sy must +check the API version specified +by the +.Nm sudo +front-end before using +.Fa plugin_options . +Failure to do so may result in a crash. +.It Fa errstr +If the +.Fn open +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa close +.Bd -literal -compact +void (*close)(int exit_status, int error); +.Ed +.Pp +The +.Fn close +function is called when +.Nm sudo +is finished, shortly before it exits. +Starting with API version 1.15, +.Fn close +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 +.Fn close +function. +To determine if a command was actually run, +the plugin must keep track of whether or not the +.Fn check_policy +function returned successfully. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa exit_status +The command's exit status, as returned by the +.Xr wait 2 +system call, or zero if no command was run. +The value of +.Fa exit_status +is undefined if +.Fa error +is non-zero. +.It Fa error +If the command could not be executed, this is set to the value of +.Va errno +set by the +.Xr execve 2 +system call. +The plugin is responsible for displaying error information via the +.Fn conversation +or +.Fn sudo_plugin_printf +function. +If the command was successfully executed, the value of +.Fa error +is zero. +.El +.Pp +If no +.Fn close +function is defined, no I/O logging plugins are loaded, +and neither the +.Em timeout +nor +.Em use_pty +options are set in the +.Fa command_info +list, the +.Nm sudo +front-end may execute the command directly instead of running +it as a child process. +.It Fa show_version +.Bd -literal -compact +int (*show_version)(int verbose); +.Ed +.Pp +The +.Fn show_version +function is called by +.Nm sudo +when the user specifies the +.Fl V +option. +The plugin may display its version information to the user via the +.Fn conversation +or +.Fn sudo_plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG . +If the user requests detailed version information, the +.Fa verbose +flag will be non-zero. +.Pp +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. +.It Fa check_policy +.Bd -literal -compact +int (*check_policy)(int argc, char * const argv[], char *env_add[], + char **command_info[], char **argv_out[], char **user_env_out[], + const char **errstr); +.Ed +.Pp +The +.Fn check_policy +function is called by +.Nm sudo +to determine +whether the user is allowed to run the specified commands. +.Pp +If the +.Em sudoedit +option was enabled in the +.Fa settings +array passed to the +.Fn open +function, the user has requested +.Em sudoedit +mode. +.Em sudoedit +is a mechanism for editing one or more files +where an editor is run with the user's credentials instead of with +elevated privileges. +.Nm sudo +achieves this by creating user-writable +temporary copies of the files to be edited and then overwriting the +originals with the temporary copies after editing is complete. +If the plugin supports +.Em sudoedit , +it must set +.Em sudoedit=true +in the +.Fa command_info +list. +The plugin is responsible for choosing the editor to be used, +potentially from a variable in the user's environment, such as +.Ev EDITOR , +and should be stored in +.Fa argv_out +(environment variables may include command line options). +The files to be edited should be copied from +.Fa argv +to +.Fa argv_out , +separated from the +editor and its arguments by a +.Ql -- +element. +The +.Ql -- +will be removed by +.Nm sudo +before the editor is executed. +The plugin may also set +.Em sudoedit_nfiles +to the number of files to be edited in the +.Fa command_info +list; this will only be used by the +.Nm sudo +front-end starting with API version 1.21. +.Pp +The +.Fn check_policy +function returns 1 if the command is allowed, +0 if not allowed, \-1 for a general error, or \-2 for a usage error +or if +.Em sudoedit +was specified but is unsupported by the plugin. +In the latter case, +.Nm sudo +will print a usage message before it +exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa argc +The number of elements in +.Fa argv , +not counting the final +.Dv NULL +pointer. +.It Fa argv +The argument vector describing the command the user wishes to run, +in the same form as what would be passed to the +.Xr execve 2 +system call. +The vector is terminated by a +.Dv NULL +pointer. +.It Fa env_add +Additional environment variables specified by the user on the command +line in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +The plugin may reject the command if one or more variables +are not allowed to be set, or it may silently ignore such variables. +.Pp +When parsing +.Fa env_add , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one itself but the +.Em value +might. +.It Fa command_info +Information about the command being run in the form of +.Dq name=value +strings. +These values are used by +.Nm sudo +to set the execution environment when running a command. +The plugin is responsible for creating and populating the vector, +which must be terminated with a +.Dv NULL +pointer. +The following values are recognized by +.Nm sudo : +.Bl -tag -width 4n +.It apparmor_profile=string +AppArmor profile to transition to when executing the command. +Only available starting with API version 1.19. +.It chroot=string +The root directory to use when running the command. +.It closefrom=number +If specified, +.Nm sudo +will close all files descriptors with a value +of +.Em number +or higher. +.It command=string +Fully qualified path to the command to be executed. +.It cwd=string +The current working directory to change to when executing the command. +If +.Nm sudo +is unable to change to the new working directory, the command will +not be run unless +.Em cwd_optional +is also set (see below). +.It cwd_optional=bool +If set, +.Nm sudo +will treat an inability to change to the new working directory as a +non-fatal error. +This setting has no effect unless +.Em cwd +is also set. +.It exec_background=bool +By default, +.Nm sudo +runs a command as the foreground process as long as +.Nm sudo +itself is running in the foreground. +When +.Em exec_background +is enabled and the command is being run in a pseudo-terminal +(due to I/O logging or the +.Em use_pty +setting), the command will be run as a background process. +Attempts to read from the controlling terminal (or to change terminal +settings) will result in the command being suspended with the +.Dv SIGTTIN +signal (or +.Dv SIGTTOU +in the case of terminal settings). +If this happens when +.Nm sudo +is a foreground process, the command will be granted the controlling terminal +and resumed in the foreground with no user intervention required. +The advantage of initially running the command in the background is that +.Nm sudo +need not read from the terminal unless the command explicitly requests it. +Otherwise, any terminal input must be passed to the command, whether it +has required it or not (the kernel buffers terminals so it is not possible +to tell whether the command really wants the input). +This is different from historic +.Nm sudo +behavior or when the command is not being run in a pseudo-terminal. +.Pp +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 +.Fn tcgetattr +and +.Fn tcsetattr +system calls (this is a bug in macOS). +Furthermore, because this behavior depends on the command stopping with the +.Dv SIGTTIN +or +.Dv SIGTTOU +signals, programs that catch these signals and suspend themselves +with a different signal (usually +.Dv SIGTOP ) +will not be automatically foregrounded. +Some versions of the linux +.Xr su 1 +command behave this way. +Because of this, a plugin should not set +.Em exec_background +unless it is explicitly enabled by the administrator and there should +be a way to enabled or disable it on a per-command basis. +.Pp +This setting has no effect unless I/O logging is enabled or +.Em use_pty +is enabled. +.It execfd=number +If specified, +.Nm sudo +will use the +.Xr fexecve 2 +system call to execute the command instead of +.Xr execve 2 . +The specified +.Em number +must refer to an open file descriptor. +.It intercept=bool +If set, +.Nm sudo +will intercept attempts to execute a subsequent command and perform +a policy check via the policy plugin's +.Fn check_policy +function to determine whether or not the command is permitted. +This can be used to prevent shell escapes on supported platforms +but it has a number of limitations. +See +.Sy Preventing shell escapes +in +.Xr sudoers @mansectform@ +for details. +Only available starting with API version 1.18. +.It intercept_verify=bool +If set, +.Nm sudo +will attempt to verify that a command run in intercept mode has the +expected path name, command line arguments and environment. +This setting has no effect unless +.Em use_ptrace +is also enabled. +Only available starting with API version 1.20. +.It iolog_compress=bool +Set to true if the I/O logging plugins, if any, should compress the +log data. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It iolog_group=string +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. +.It iolog_mode=octal +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. +.It iolog_user=string +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. +.It iolog_path=string +Fully qualified path to the file or directory in which I/O log is +to be stored. +This is a hint to the I/O logging plugin which may choose to ignore it. +If no I/O logging plugin is loaded, this setting has no effect. +.It iolog_stdin=bool +Set to true if the I/O logging plugins, if any, should log the +standard input if it is not connected to a terminal device. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It iolog_stdout=bool +Set to true if the I/O logging plugins, if any, should log the +standard output if it is not connected to a terminal device. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It iolog_stderr=bool +Set to true if the I/O logging plugins, if any, should log the +standard error if it is not connected to a terminal device. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It iolog_ttyin=bool +Set to true if the I/O logging plugins, if any, should log all +terminal input. +This only includes input typed by the user and not from a pipe or +redirected from a file. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It iolog_ttyout=bool +Set to true if the I/O logging plugins, if any, should log all +terminal output. +This only includes output to the screen, not output to a pipe or file. +This is a hint to the I/O logging plugin which may choose to ignore it. +.It login_class=string +.Bx +login class to use when setting resource limits and nice value (optional). +This option is only set on systems that support login classes. +.It nice=int +Nice value (priority) to use when executing the command. +The nice value, if specified, overrides the priority associated with the +.Em login_class +on +.Bx +systems. +.It log_subcmds=bool +If set, +.Nm sudo +will call the audit plugin's +.Fn accept +function to log when the command runs a subsequent command, if supported +by the system. +If +.Em intercept +is also specified, +.Em log_subcmds +will be ignored. +See +.Sy Preventing shell escapes +in +.Xr sudoers @mansectform@ +for more information. +Only available starting with API version 1.18. +.It noexec=bool +If set, prevent the command from executing other programs. +.It preserve_fds=list +A comma-separated list of file descriptors that should be +preserved, regardless of the value of the +.Em closefrom +setting. +Only available starting with API version 1.5. +.It preserve_groups=bool +If set, +.Nm sudo +will preserve the user's group vector instead of +initializing the group vector based on +.Em runas_user . +.It rlimit_as=soft,hard +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. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_core=soft,hard +The largest size core dump file that may be created (in bytes). +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_cpu=soft,hard +The maximum amount of CPU time that the process may use (in seconds). +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_data=soft,hard +The maximum size of the data segment for the process (in bytes). +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_fsize=soft,hard +The largest size file that the process may create (in bytes). +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_locks=soft,hard +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. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_memlock=soft,hard +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. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_nofile=soft,hard +The maximum number of files that the process may have open. +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_nproc=soft,hard +The maximum number of processes that the user may run simultaneously. +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_rss=soft,hard +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. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It rlimit_stack=soft,hard +The maximum size to which the process's stack may grow (in bytes). +The soft and hard limits are separated by a comma. +If only a single value is specified, both the hard and soft limits are set. +A value of +.Dq infinity +indicates that there is no limit. +A value of +.Dq user +will cause the invoking user's resource limit to be preserved. +A value of +.Dq default +will cause the target user's default resource limit to be used +on systems that allow per-user resource limits to be configured. +Only available starting with API version 1.18. +.It runas_egid=gid +Effective group-ID to run the command as. +If not specified, the value of +.Em runas_gid +is used. +.It runas_euid=uid +Effective user-ID to run the command as. +If not specified, the value of +.Em runas_uid +is used. +.It runas_gid=gid +Group-ID to run the command as. +.It runas_group=string +The name of the group the command will run as, if it is different +from the +.Em runas_user Ns 's +default group. +This value is provided for auditing purposes only, the +.Nm sudo +front-end uses +.Em runas_egid +and +.Em runas_gid +when executing the command. +.It runas_groups=list +The supplementary group vector to use for the command in the form +of a comma-separated list of group-IDs. +If +.Em preserve_groups +is set, this option is ignored. +.It runas_uid=uid +User-ID to run the command as. +.It runas_user=string +The name of the user the command will run as, which should correspond to +.Em runas_euid +(or +.Em runas_uid +if +.Em runas_euid +is not set). +This value is provided for auditing purposes only, the +.Nm sudo +front-end uses +.Em runas_euid +and +.Em runas_uid +when executing the command. +.It selinux_role=string +SELinux role to use when executing the command. +.It selinux_type=string +SELinux type to use when executing the command. +.It set_utmp=bool +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. +.It sudoedit=bool +Set to true when in +.Em sudoedit +mode. +The plugin may enable +.Em sudoedit +mode even if +.Nm sudo +was not invoked as +.Nm sudoedit . +This allows the plugin to perform command substitution and transparently +enable +.Em sudoedit +when the user attempts to run an editor. +.It sudoedit_checkdir=bool +Set to false to disable directory writability checks in +.Nm sudoedit . +By default, +.Nm sudoedit +1.8.16 and higher will check all directory components of the path to be +edited for writability by the invoking user. +Symbolic links will not be followed in writable directories and +.Nm sudoedit +will refuse to edit a file located in a writable directory. +These restrictions are not enforced when +.Nm sudoedit +is run by root. +The +.Em sudoedit_checkdir +option can be set to false to disable this check. +Only available starting with API version 1.8. +.It sudoedit_follow=bool +Set to true to allow +.Nm sudoedit +to edit files that are symbolic links. +By default, +.Nm sudoedit +1.8.15 and higher will refuse to open a symbolic link. +The +.Em sudoedit_follow +option can be used to restore the older behavior and allow +.Nm sudoedit +to open symbolic links. +Only available starting with API version 1.8. +.It sudoedit_nfiles=number +The number of files to be edited by the user. +If present, this is will be used by the +.Nm sudo +front-end to determine which elements of the +.Fa argv_out +vector are files to be edited. +The +.Ql -- +element must immediately precede the first file to be editied. +If +.Em sudoedit_nfiles +is not specified, the +.Nm sudo +front-end will use the position of the +.Ql -- +element to determine where the file list begins. +Only available starting with API version 1.21. +.It timeout=int +Command timeout. +If non-zero then when the timeout expires the command will be killed. +.It umask=octal +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 +.Em umask_override +option is also set. +.It umask_override=bool +Force the value specified by the +.Em umask +option to override any umask set by PAM or login.conf. +.It use_ptrace=bool +If set, +.Nm sudo +will use +.Xr ptrace 2 +to implement intercept mode if supported by the system. +This setting has no effect unless +.Em intercept +is also set. +Only available starting with API version 1.19. +.It use_pty=bool +Allocate a pseudo-terminal to run the command in, regardless of whether +or not I/O logging is in use. +By default, +.Nm sudo +will only run +the command in a pseudo-terminal when an I/O log plugin is loaded. +.It utmp_user=string +User name to use when constructing a new utmp (or utmpx) entry when +.Em set_utmp +is enabled. +This option can be used to set the user field in the utmp entry to +the user the command runs as rather than the invoking user. +If not set, +.Nm sudo +will base the new entry on +the invoking user's existing entry. +.El +.Pp +Unsupported values will be ignored. +.It Fa argv_out +The +.Dv NULL Ns -terminated +argument vector to pass to the +.Xr execve 2 +system call when executing the command. +The plugin is responsible for allocating and populating the vector. +.It Fa user_env_out +The +.Dv NULL Ns -terminated +environment vector to use when executing the command. +The plugin is responsible for allocating and populating the vector. +.It Fa errstr +If the +.Fn check_policy +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa list +.Bd -literal -compact +int (*list)(int argc, char * const argv[], int verbose, + const char *user, const char **errstr); +.Ed +.Pp +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 +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to +the user. +.Pp +Privileges should be output via the +.Fn conversation +or +.Fn sudo_plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG . +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa argc +The number of elements in +.Fa argv , +not counting the final +.Dv NULL +pointer. +.It Fa argv +If +.No non- Ns Dv NULL , +an argument vector describing a command the user +wishes to check against the policy in the same form as what would +be passed to the +.Xr execve 2 +system call. +If the command is permitted by the policy, the fully-qualified path +to the command should be displayed along with any command line arguments. +.It Fa verbose +Flag indicating whether to list in verbose mode or not. +.It Fa user +The name of a different user to list privileges for if the policy +allows it. +If +.Dv NULL , +the plugin should list the privileges of the invoking user. +.It Fa errstr +If the +.Fn list +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa validate +.Bd -literal -compact +int (*validate)(const char **errstr); +.Ed +.Pp +The +.Fn validate +function is called when +.Nm sudo +is run with the +.Fl v +option. +For policy plugins such as +.Nm sudoers +that cache +authentication credentials, this function will validate and cache +the credentials. +.Pp +The +.Fn validate +function should be +.Dv NULL +if the plugin does not support credential caching. +.Pp +Returns 1 on success, 0 on failure, and \-1 on error. +On error, the plugin may optionally call the +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional +error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Va errstr +If the +.Fn validate +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa invalidate +.Bd -literal -compact +void (*invalidate)(int rmcred); +.Ed +.Pp +The +.Fn invalidate +function is called when +.Nm sudo +is run with the +.Fl k +or +.Fl K +option. +For policy plugins such as +.Nm sudoers +that +cache authentication credentials, this function will invalidate the +credentials. +If the +.Fa rmcred +flag is non-zero, the plugin may remove +the credentials instead of simply invalidating them. +.Pp +The +.Fn invalidate +function should be +.Dv NULL +if the plugin does not support credential caching. +.It Fa init_session +.Bd -literal -compact +int (*init_session)(struct passwd *pwd, char **user_env[], + const char **errstr); +.Ed +.Pp +The +.Fn init_session +function is called before +.Nm sudo +sets up the +execution environment for the command. +It is run in the parent +.Nm sudo +process before any user-ID or group-ID changes. +This can be used to perform session setup that is not supported by +.Fa command_info , +such as opening the PAM session. +The +.Fn close +function can be +used to tear down the session that was opened by +.Fn init_session . +.Pp +Returns 1 on success, 0 on failure, and \-1 on error. +On error, the plugin may optionally call the +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional +error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa pwd +If the user-ID the command will run as was found in the password database, +.Fa pwd +will describe that user, otherwise it will be +.Dv NULL . +.It Fa user_env_out +The +.Dv NULL Ns -terminated +environment vector to use when executing the command. +This is the same string passed back to the front-end via the Policy Plugin's +.Fa user_env_out +parameter. +If the +.Fn init_session +function needs to modify the user environment, it should update the +pointer stored in +.Fa user_env_out . +The expected use case is to merge the contents of the PAM environment +(if any) with the contents of +.Fa user_env_out . +The +.Fa user_env_out +parameter is only available +starting with API version 1.2. +A plugin +.Sy must +check the API +version specified by the +.Nm sudo +front-end before using +.Fa user_env_out . +Failure to do so may result in a crash. +.It Fa errstr +If the +.Fn init_session +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa register_hooks +.Bd -literal -compact +void (*register_hooks)(int version, + int (*register_hook)(struct sudo_hook *hook)); +.Ed +.Pp +The +.Fn register_hooks +function is called by the sudo front-end to +register any hooks the plugin needs. +If the plugin does not support hooks, +.Fa register_hooks +should be set to the +.Dv NULL +pointer. +.Pp +The +.Fa version +argument describes the version of the hooks API +supported by the +.Nm sudo +front-end. +.Pp +The +.Fn register_hook +function should be used to register any supported +hooks the plugin needs. +It returns 0 on success, 1 if the hook type is not supported, and \-1 +if the major version in +.Vt struct sudo_hook +does not match the front-end's major hook API version. +.Pp +See the +.Sx Hook function API +section below for more information about hooks. +.Pp +The +.Fn register_hooks +function is only available starting +with API version 1.2. +If the +.Nm sudo +front-end doesn't support API +version 1.2 or higher, +.Fn register_hooks +will not be called. +.It Fa deregister_hooks +.Bd -literal -compact +void (*deregister_hooks)(int version, + int (*deregister_hook)(struct sudo_hook *hook)); +.Ed +.Pp +The +.Fn deregister_hooks +function is called by the sudo front-end +to deregister any hooks the plugin has registered. +If the plugin does not support hooks, +.Fa deregister_hooks +should be set to the +.Dv NULL +pointer. +.Pp +The +.Fa version +argument describes the version of the hooks API +supported by the +.Nm sudo +front-end. +.Pp +The +.Fn deregister_hook +function should be used to deregister any +hooks that were put in place by the +.Fn register_hook +function. +If the plugin tries to deregister a hook that the front-end does not support, +.Fn deregister_hook +will return an error. +.Pp +See the +.Sx Hook function API +section below for more information about hooks. +.Pp +The +.Fn deregister_hooks +function is only available starting +with API version 1.2. +If the +.Nm sudo +front-end doesn't support API +version 1.2 or higher, +.Fn deregister_hooks +will not be called. +.It Fa event_alloc +.Bd -literal -compact +struct sudo_plugin_event * (*event_alloc)(void); +.Ed +.Pp +The +.Fn event_alloc +function is used to allocate a +.Vt struct sudo_plugin_event +which provides access to the main +.Nm sudo +event loop. +Unlike the other fields, the +.Fa event_alloc +pointer is filled in by the +.Nm sudo +front-end, not by the plugin. +.Pp +See the +.Sx Event API +section below for more information +about events. +.Pp +The +.Fn event_alloc +function is only available starting +with API version 1.15. +If the +.Nm sudo +front-end doesn't support API +version 1.15 or higher, +.Fa event_alloc +will not be set. +.El +.Pp +.Em Policy Plugin Version Macros +.Bd -literal +/* 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,\e + 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 { \e + *(vp) = (*(vp) & 0x0000ffff) | ((n) << 16); \e +} while(0) +#define SUDO_API_VERSION_SET_MINOR(vp, n) do { \e + *(vp) = (*(vp) & 0xffff0000) | (n); \e +} while(0) +.Ed +.Ss I/O plugin API +.Bd -literal +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 sudo_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); +}; +.Ed +.Pp +When an I/O plugin is loaded, +.Nm sudo +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, +.Nm sudo +will open a pipe to capture the I/O for logging before passing it on. +.Pp +The +.Fn log_ttyin +function receives the raw user input from the terminal +device (this will include input even when echo is disabled, +such as when a password is read). +The +.Fn log_ttyout +function receives output from the pseudo-terminal that is +suitable for replaying the user's session at a later time. +The +.Fn log_stdin , +.Fn log_stdout , +and +.Fn log_stderr +functions are only called if the standard input, standard output, +or standard error respectively correspond to something other than +a tty. +.Pp +Any of the logging functions may be set to the +.Dv NULL +pointer if no logging is to be performed. +If the open function returns 0, no I/O will be sent to the plugin. +.Pp +If a logging function returns an error +.Pq \-1 , +the running command will be terminated and all of the plugin's logging +functions will be disabled. +Other I/O logging plugins will still receive any remaining +input or output that has not yet been processed. +.Pp +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. +.Pp +A +.Vt struct audit_plugin +has the following fields: +.Bl -tag -width 4n +.It Fa type +The +.Fa type +field should always be set to +.Dv SUDO_IO_PLUGIN . +.It Fa version +The +.Fa version +field should be set to +.Dv SUDO_API_VERSION . +.Pp +This allows +.Nm sudo +to determine the API version the plugin was +built against. +.It Fa open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_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[]); +.Ed +.Pp +The +.Fn open +function is run before the +.Fn log_ttyin , +.Fn log_ttyout , +.Fn log_stdin , +.Fn log_stdout , +.Fn log_stderr , +.Fn log_suspend , +.Fn change_winsize , +or +.Fn show_version +functions are called. +It is only called if the version is being requested or if the +policy plugin's +.Fn check_policy +function has returned successfully. +It returns 1 on success, 0 on failure, \-1 if a general error occurred, +or \-2 if there was a usage error. +In the latter case, +.Nm sudo +will print a usage message before it exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn sudo_plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa version +The version passed in by +.Nm sudo +allows the plugin to determine the +major and minor version number of the plugin API supported by +.Nm sudo . +.It Fa conversation +A pointer to the +.Fn conversation +function that may be used by the +.Fn Fa show_version +function to display version information (see +.Fn show_version +below). +The +.Fn conversation +function may also be used to display additional error message to the user. +The +.Fn conversation +function returns 0 on success and \-1 on failure. +.It Fa sudo_plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used by the +.Fn show_version +function to display version information (see +show_version below). +The +.Fn sudo_plugin_printf +function may also be used to display additional error message to the user. +The +.Fn sudo_plugin_printf +function returns number of characters printed on success and \-1 on failure. +.It Fa settings +A vector of user-supplied +.Nm sudo +settings in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +These settings correspond to options the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding option has +been specified on the command line. +.Pp +When parsing +.Fa settings , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible settings. +.It Fa user_info +A vector of information about the user running the command in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa user_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa command_info +A vector of information describing the command being run in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa command_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa argc +The number of elements in +.Fa argv , +not counting the final +.Dv NULL +pointer. +It can be zero, such as when +.Nm sudo +is called with the +.Fl V +option. +.It Fa argv +If +.No non- Ns Dv NULL , +an argument vector describing a command the user +wishes to run in the same form as what would be passed to the +.Xr execve 2 +system call. +.It Fa user_env +The user's environment in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa user_env , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa plugin_options +Any (non-comment) strings immediately after the plugin path are +treated as arguments to the plugin. +These arguments are split on a white space boundary and are passed to +the plugin in the form of a +.Dv NULL Ns -terminated +array of strings. +If no arguments were specified, +.Fa plugin_options +will be the +.Dv NULL +pointer. +.Pp +The +.Fa plugin_options +parameter is only available starting with +API version 1.2. +A plugin +.Sy must +check the API version specified +by the +.Nm sudo +front-end before using +.Fa plugin_options . +Failure to do so may result in a crash. +.It Fa errstr +If the +.Fn open +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa close +.Bd -literal -compact +void (*close)(int exit_status, int error); +.Ed +.Pp +The +.Fn close +function is called when +.Nm sudo +is finished, shortly before it exits. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa exit_status +The command's exit status, as returned by the +.Xr wait 2 +system call, or zero if no command was run. +The value of +.Fa exit_status +is undefined if +.Fa error +is non-zero. +.It Fa error +If the command could not be executed, this is set to the value of +.Va errno +set by the +.Xr execve 2 +system call. +If the command was successfully executed, the value of +.Fa error +is zero. +.El +.It Fa show_version +.Bd -literal -compact +int (*show_version)(int verbose); +.Ed +.Pp +The +.Fn show_version +function is called by +.Nm sudo +when the user specifies the +.Fl V +option. +The plugin may display its version information to the user via the +.Fn conversation +or +.Fn sudo_plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG . +If the user requests detailed version information, the +.Fa verbose +flag will be non-zero. +.Pp +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. +.It Fa log_ttyin +.Bd -literal -compact +int (*log_ttyin)(const char *buf, unsigned int len, + const char **errstr); +.Ed +.Pp +The +.Fn log_ttyin +function is called whenever data can be read from +the user but before it is passed to the running command. +This allows the plugin to reject data if it chooses to (for instance +if the input contains banned content). +Returns 1 if the data should be passed to the command, 0 if the data +is rejected (which will terminate the running command), or \-1 if an +error occurred. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa buf +The buffer containing user input. +.It Fa len +The length of +.Fa buf +in bytes. +.It Fa errstr +If the +.Fn log_ttyin +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa log_ttyout +.Bd -literal -compact +int (*log_ttyout)(const char *buf, unsigned int len, + const char **errstr); +.Ed +.Pp +The +.Fn log_ttyout +function is called whenever data can be read from +the command but before it is written to the user's terminal. +This allows the plugin to reject data if it chooses to (for instance +if the output contains banned content). +Returns 1 if the data should be passed to the user, 0 if the data is rejected +(which will terminate the running command), or \-1 if an error occurred. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa buf +The buffer containing command output. +.It Fa len +The length of +.Fa buf +in bytes. +.It Fa errstr +If the +.Fn log_ttyout +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa log_stdin +.Bd -literal -compact +int (*log_stdin)(const char *buf, unsigned int len, + const char **errstr); +.Ed +.Pp +The +.Fn log_stdin +function is only used if the standard input does +not correspond to a tty device. +It is called whenever data can be read from the standard input but +before it is passed to the running command. +This allows the plugin to reject data if it chooses to +(for instance if the input contains banned content). +Returns 1 if the data should be passed to the command, 0 if the +data is rejected (which will terminate the running command), or \-1 +if an error occurred. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa buf +The buffer containing user input. +.It Fa len +The length of +.Fa buf +in bytes. +.It Fa errstr +If the +.Fn log_stdin +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa log_stdout +.Bd -literal -compact +int (*log_stdout)(const char *buf, unsigned int len, + const char **errstr); +.Ed +.Pp +The +.Fn log_stdout +function is only used if the standard output does not correspond +to a tty device. +It is called whenever data can be read from the command but before +it is written to the standard output. +This allows the plugin to reject data if it chooses to +(for instance if the output contains banned content). +Returns 1 if the data should be passed to the user, 0 if the data +is rejected (which will terminate the running command), or \-1 if +an error occurred. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa buf +The buffer containing command output. +.It Fa len +The length of +.Fa buf +in bytes. +.It Fa errstr +If the +.Fn log_stdout +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa log_stderr +.Bd -literal -compact +int (*log_stderr)(const char *buf, unsigned int len, + const char **errstr); +.Ed +.Pp +The +.Fn log_stderr +function is only used if the standard error does +not correspond to a tty device. +It is called whenever data can be read from the command but before it +is written to the standard error. +This allows the plugin to reject data if it chooses to +(for instance if the output contains banned content). +Returns 1 if the data should be passed to the user, 0 if the data +is rejected (which will terminate the running command), or \-1 if +an error occurred. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa buf +The buffer containing command output. +.It Fa len +The length of +.Fa buf +in bytes. +.It Fa errstr +If the +.Fn log_stderr +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa register_hooks +See the +.Sx Policy plugin API +section for a description of +.Fn register_hooks . +.It Fa deregister_hooks +See the +.Sx Policy plugin API +section for a description of +.Fn deregister_hooks . +.It Fa change_winsize +.Bd -literal -compact +int (*change_winsize)(unsigned int lines, unsigned int cols, + const char **errstr); +.Ed +.Pp +The +.Fn change_winsize +function is called whenever the window size of the terminal changes from +the initial values specified in the +.Fa user_info +list. +Returns \-1 if an error occurred, in which case no further calls to +.Fn change_winsize +will be made, +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa lines +The number of lines (rows) in the re-sized terminal. +.It Fa cols +The number of columns in the re-sized terminal. +.It Fa errstr +If the +.Fn change_winsize +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.El +.It Fa log_suspend +.Bd -literal -compact +int (*log_suspend)(int signo, const char **errstr); +.Ed +.Pp +The +.Fn log_suspend +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 +.Fn log_suspend +will be made, +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa signo +The signal that caused the command to be suspended, or +.Dv SIGCONT +if the command was resumed. +.It Fa errstr +If the +.Fn log_suspend +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.Pp +The +.Fa errstr +parameter is only available starting with +API version 1.15. +A plugin +.Sy must +check the API version specified by the +.Nm sudo +front-end before using +.Fa errstr . +Failure to do so may result in a crash. +.It Fa event_alloc +.Bd -literal -compact +struct sudo_plugin_event * (*event_alloc)(void); +.Ed +.Pp +The +.Fn event_alloc +function is used to allocate a +.Vt struct sudo_plugin_event +which provides access to the main +.Nm sudo +event loop. +Unlike the other fields, the +.Fn event_alloc +pointer is filled in by the +.Nm sudo +front-end, not by the plugin. +.Pp +See the +.Sx Event API +section below for more information +about events. +.Pp +The +.Fn event_alloc +function is only available starting +with API version 1.15. +If the +.Nm sudo +front-end doesn't support API +version 1.15 or higher, +.Fn event_alloc +will not be set. +.El +.Pp +.Em I/O Plugin Version Macros +.Pp +Same as for the +.Sx Policy plugin API . +.El +.Ss Audit plugin API +.Bd -literal +/* 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_plugin_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); +} +.Ed +.Pp +An audit plugin can be used to log successful and unsuccessful attempts +to run +.Nm sudo +independent of the policy or any I/O plugins. +Multiple audit plugins may be specified in +.Xr sudo.conf @mansectform@ . +.Pp +A +.Vt struct audit_plugin +has the following fields: +.Bl -tag -width 4n +.It Fa type +The +.Fa type +field should always be set to +.Dv SUDO_AUDIT_PLUGIN . +.It Fa version +The +.Fa version +field should be set to +.Dv SUDO_API_VERSION . +.Pp +This allows +.Nm sudo +to determine the API version the plugin was +built against. +.It Fa open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_plugin_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); +.Ed +.Pp +The audit +.Fn open +function is run before any other +.Nm sudo +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, +.Nm sudo +will print a usage message before it exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa version +The version passed in by +.Nm sudo +allows the plugin to determine the +major and minor version number of the plugin API supported by +.Nm sudo . +.It Fa conversation +A pointer to the +.Fn conversation +function that may be used by the +.Fn show_version +function to display version information (see +.Fn show_version +below). +The +.Fn conversation +function may also be used to display additional error message to the user. +The +.Fn conversation +function returns 0 on success, and \-1 on failure. +.It Fa plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used by the +.Fn show_version +function to display version information (see +show_version below). +The +.Fn plugin_printf +function may also be used to display additional error message to the user. +The +.Fn plugin_printf +function returns number of characters printed on success and \-1 on failure. +.It Fa settings +A vector of user-supplied +.Nm sudo +settings in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +These settings correspond to options the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding option has +been specified on the command line. +.Pp +When parsing +.Fa settings , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible settings. +.It Fa user_info +A vector of information about the user running the command in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa user_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa submit_optind +The index into +.Fa submit_argv +that corresponds to the first entry that is not a command line option. +If +.Fa submit_argv +only consists of options, which may be the case with the +.Fl l +or +.Fl v +options, +.Fa submit_argv Ns [ Fa submit_optind ] +will evaluate to the NULL pointer. +.It Fa submit_argv +The argument vector +.Nm sudo +was invoked with, including all command line options. +The +.Fa submit_optind +argument can be used to determine the end of the command line options. +.It Fa submit_envp +The invoking user's environment in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa submit_envp , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa plugin_options +Any (non-comment) strings immediately after the plugin path are +treated as arguments to the plugin. +These arguments are split on a white space boundary and are passed to +the plugin in the form of a +.Dv NULL Ns -terminated +array of strings. +If no arguments were specified, +.Fa plugin_options +will be the +.Dv NULL +pointer. +.It Fa errstr +If the +.Fn open +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa close +.Bd -literal -compact +void (*close)(int status_type, int status); +.Ed +.Pp +The +.Fn close +function is called when +.Nm sudo +is finished, shortly before it exits. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa status_type +The type of status being passed. +One of +.Dv SUDO_PLUGIN_NO_STATUS , +.Dv SUDO_PLUGIN_WAIT_STATUS , +.Dv SUDO_PLUGIN_EXEC_ERROR +or +.Dv SUDO_PLUGIN_SUDO_ERROR . +.It Fa status +Depending on the value of +.Fa status_type , +this value is either +ignored, the command's exit status as returned by the +.Xr wait 2 +system call, the value of +.Va errno +set by the +.Xr execve 2 +system call, or the value of +.Va errno +resulting from an error in the +.Nm sudo +front-end. +.El +.It Fa accept +.Bd -literal -compact +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); +.Ed +.Pp +The +.Fn accept +function is called when a command or action is accepted by a policy +or approval plugin. +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa plugin_name +The name of the plugin that accepted the command or +.Dq sudo +for the +.Nm sudo +front-end. +.It Fa plugin_type +The type of plugin that accepted the command, currently either +.Dv SUDO_POLICY_PLUGIN , +.Dv SUDO_POLICY_APPROVAL , +or +.Dv SUDO_FRONT_END . +The +.Fn 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, +.Fa command_info +may include information from an I/O logging plugin as well. +.Pp +Typically, an audit plugin is interested in either the accept status from +the +.Nm 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 +.Fn accept +and +.Fn reject +functions will +.Em both +be called. +.It Fa command_info +An optional +vector of information describing the command being run in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa command_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa run_argv +A +.Dv NULL Ns -terminated +argument vector describing a command that will be run in the +same form as what would be passed to the +.Xr execve 2 +system call. +.It Fa run_envp +The environment the command will be run with in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa run_envp , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa errstr +If the +.Fn accept +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa reject +.Bd -literal -compact +int (*reject)(const char *plugin_name, unsigned int plugin_type, + const char *audit_msg, char * const command_info[], + const char **errstr); +.Ed +.Pp +The +.Fn reject +function is called when a command or action is rejected by a plugin. +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa plugin_name +The name of the plugin that rejected the command. +.It Fa plugin_type +The type of plugin that rejected the command, currently either +.Dv SUDO_POLICY_PLUGIN , +.Dv SUDO_APPROVAL_PLUGIN , +or +.Dv SUDO_IO_PLUGIN . +.Pp +Unlike the +.Fn accept +function, the +.Fn reject +function is not called on behalf of the +.Nm sudo +front-end. +.It Fa audit_msg +An optional string describing the reason the command was rejected +by the plugin. +If the plugin did not provide a reason, +.Fa audit_msg +will be the +.Dv NULL +pointer. +.It Fa command_info +An optional +vector of information describing the command being run in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa command_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa errstr +If the +.Fn reject +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa error +.Bd -literal -compact +int (*error)(const char *plugin_name, unsigned int plugin_type, + const char *audit_msg, char * const command_info[], + const char **errstr); +.Ed +.Pp +The +.Fn error +function is called when a plugin or the +.Nm sudo +front-end returns an error. +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa plugin_name +The name of the plugin that generated the error or +.Dq sudo +for the +.Nm sudo +front-end. +.It Fa plugin_type +The type of plugin that generated the error, or +.Dv SUDO_FRONT_END +for the +.Nm sudo +front-end. +.It Fa audit_msg +An optional string describing the plugin error. +If the plugin did not provide a description, +.Fa audit_msg +will be the +.Dv NULL +pointer. +.It Fa command_info +An optional +vector of information describing the command being run in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa command_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa errstr +If the +.Fn error +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa show_version +.Bd -literal -compact +int (*show_version)(int verbose); +.Ed +.Pp +The +.Fn show_version +function is called by +.Nm sudo +when the user specifies the +.Fl V +option. +The plugin may display its version information to the user via the +.Fn conversation +or +.Fn plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG . +If the user requests detailed version information, the verbose flag will be set. +.Pp +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. +.It Fa register_hooks +See the +.Sx Policy plugin API +section for a description of +.Fn register_hooks . +.It Fa deregister_hooks +See the +.Sx Policy plugin API +section for a description of +.Fn deregister_hooks . +.It Fa event_alloc +.Bd -literal -compact +struct sudo_plugin_event * (*event_alloc)(void); +.Ed +.Pp +The +.Fn event_alloc +function is used to allocate a +.Vt struct sudo_plugin_event +which provides access to the main +.Nm sudo +event loop. +Unlike the other fields, the +.Fa event_alloc +pointer is filled in by the +.Nm sudo +front-end, not by the plugin. +.Pp +See the +.Sx Event API +section below for more information +about events. +.Pp +The +.Fn event_alloc +function is only available starting +with API version 1.17. +If the +.Nm sudo +front-end doesn't support API +version 1.17 or higher, +.Fn event_alloc +will not be set. +.El +.Ss Approval plugin API +.Bd -literal +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_plugin_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); +}; +.Ed +.Pp +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 +.Fn check +or +.Fn show_version +and closed shortly thereafter (audit plugin functions must be called +before the plugin is closed). +Multiple approval plugins may be specified in +.Xr sudo.conf @mansectform@ . +.Pp +A +.Vt struct approval_plugin +has the following fields: +.Bl -tag -width 4n +.It Fa type +The +.Fa type +field should always be set to +.Dv SUDO_APPROVAL_PLUGIN . +.It Fa version +The +.Fa version +field should be set to +.Dv SUDO_API_VERSION . +.Pp +This allows +.Nm sudo +to determine the API version the plugin was +built against. +.It Fa open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_plugin_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); +.Ed +.Pp +The approval +.Fn open +function is run immediately before a call to the plugin's +.Fn check +or +.Fn show_version +functions. +It is only called if the version is being requested or if the +policy plugin's +.Fn check_policy +function has returned successfully. +It returns 1 on success, 0 on failure, \-1 if a general error occurred, +or \-2 if there was a usage error. +In the latter case, +.Nm sudo +will print a usage message before it exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa version +The version passed in by +.Nm sudo +allows the plugin to determine the +major and minor version number of the plugin API supported by +.Nm sudo . +.It Fa conversation +A pointer to the +.Fn conversation +function that can be used by the plugin to interact with the user (see +.Sx Conversation API +for details). +Returns 0 on success and \-1 on failure. +.It Fa plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used to display informational or error messages (see +.Sx Conversation API +for details). +Returns the number of characters printed on success and \-1 on failure. +.It Fa settings +A vector of user-supplied +.Nm sudo +settings in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +These settings correspond to options the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding option has +been specified on the command line. +.Pp +When parsing +.Fa settings , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible settings. +.It Fa user_info +A vector of information about the user running the command in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa user_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa submit_optind +The index into +.Fa submit_argv +that corresponds to the first entry that is not a command line option. +If +.Fa submit_argv +only consists of options, which may be the case with the +.Fl l +or +.Fl v +options, +.Fa submit_argv Ns [ Fa submit_optind ] +will evaluate to the NULL pointer. +.It Fa submit_argv +The argument vector +.Nm sudo +was invoked with, including all command line options. +The +.Fa submit_optind +argument can be used to determine the end of the command line options. +.It Fa submit_envp +The invoking user's environment in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa submit_envp , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa plugin_options +Any (non-comment) strings immediately after the plugin path are +treated as arguments to the plugin. +These arguments are split on a white space boundary and are passed to +the plugin in the form of a +.Dv NULL Ns -terminated +array of strings. +If no arguments were specified, +.Fa plugin_options +will be the +.Dv NULL +pointer. +.It Fa errstr +If the +.Fn open +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa close +.Bd -literal -compact +void (*close)(void); +.Ed +.Pp +The +.Fn close +function is called after the approval plugin's +.Fn check +or +.Fn show_version +functions have been called. +It takes no arguments. +The +.Fn close +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, +.Fn close +may be set to the +.Dv NULL +pointer. +.It Fa check +.Bd -literal -compact +int (*check)(char * const command_info[], char * const run_argv[], + char * const run_envp[], const char **errstr); +.Ed +.Pp +The approval +.Fn check +function is run after the policy plugin +.Fn check_policy +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, +.Nm sudo +will print a usage message before it exits. +If an error occurs, the plugin may optionally call the +.Fn conversation +or +.Fn plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa command_info +A vector of information describing the command being run in the form of +.Dq name=value +strings. +The vector is terminated by a +.Dv NULL +pointer. +.Pp +When parsing +.Fa command_info , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.Pp +See the +.Sx Policy plugin API +section for a list of all possible strings. +.It Fa run_argv +A +.Dv NULL Ns -terminated +argument vector describing a command that will be run in the +same form as what would be passed to the +.Xr execve 2 +system call. +.It Fa run_envp +The environment the command will be run with in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Fa run_envp , +the plugin should split on the +.Sy first +equal sign +.Pq Ql = +since the +.Em name +field will never include one +itself but the +.Em value +might. +.It Fa errstr +If the +.Fn open +function returns a value other than 1, the plugin may +store a message describing the failure or error in +.Fa errstr . +The +.Nm sudo +front-end will then pass this value to any registered audit plugins. +The string stored in +.Fa errstr +must remain valid until the plugin's +.Fn close +function is called. +.El +.It Fa show_version +.Bd -literal -compact +int (*show_version)(int verbose); +.Ed +.Pp +The +.Fn show_version +function is called by +.Nm sudo +when the user specifies the +.Fl V +option. +The plugin may display its version information to the user via the +.Fn conversation +or +.Fn plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG . +If the user requests detailed version information, the verbose flag will be set. +.Pp +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. +.El +.Ss Signal handlers +The +.Nm sudo +front-end installs default signal handlers to trap common signals +while the plugin functions are run. +The following signals are trapped by default before the command is +executed: +.Pp +.Bl -bullet -compact -width 1n +.It +.Dv SIGALRM +.It +.Dv SIGHUP +.It +.Dv SIGINT +.It +.Dv SIGPIPE +.It +.Dv SIGQUIT +.It +.Dv SIGTERM +.It +.Dv SIGTSTP +.It +.Dv SIGUSR1 +.It +.Dv SIGUSR2 +.El +.Pp +If a fatal signal is received before the command is executed, +.Nm sudo +will call the plugin's +.Fn close +function with an exit status of 128 plus the value of the signal +that was received. +This allows for consistent logging of commands killed by a signal +for plugins that log such information in their +.Fn close +function. +An exception to this is +.Dv SIGPIPE , +which is ignored until the command is executed. +.Pp +A plugin may temporarily install its own signal handlers but must +restore the original handler before the plugin function returns. +.Ss Hook function API +Beginning with plugin API version 1.2, it is possible to install +hooks for certain functions called by the +.Nm sudo +front-end. +.Pp +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 +.Nm sudo +front-end functions as well. +.Pp +.Em Hook structure +.Pp +Hooks in +.Nm sudo +are described by the following structure: +.Bd -literal +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; +}; +.Ed +.Pp +A +.Vt struct sudo_hook +has the following fields: +.Bl -tag -width 4n +.It Fa hook_version +The +.Fa hook_version +field should be set to +.Dv SUDO_HOOK_VERSION . +.It Fa hook_type +The +.Fa hook_type +field may be one of the following supported hook types: +.Bl -tag -width 4n +.It Dv SUDO_HOOK_SETENV +The C library +.Xr setenv 3 +function. +Any registered hooks will run before the C library implementation. +The +.Fa hook_fn +field should +be a function that matches the following typedef: +.Bd -literal +typedef int (*sudo_hook_fn_setenv_t)(const char *name, + const char *value, int overwrite, void *closure); +.Ed +.Pp +If the registered hook does not match the typedef the results are +unspecified. +.It Dv SUDO_HOOK_UNSETENV +The C library +.Xr unsetenv 3 +function. +Any registered hooks will run before the C library implementation. +The +.Fa hook_fn +field should +be a function that matches the following typedef: +.Bd -literal +typedef int (*sudo_hook_fn_unsetenv_t)(const char *name, + void *closure); +.Ed +.It Dv SUDO_HOOK_GETENV +The C library +.Xr getenv 3 +function. +Any registered hooks will run before the C library implementation. +The +.Fa hook_fn +field should +be a function that matches the following typedef: +.Bd -literal +typedef int (*sudo_hook_fn_getenv_t)(const char *name, + char **value, void *closure); +.Ed +.Pp +If the registered hook does not match the typedef the results are +unspecified. +.It Dv SUDO_HOOK_PUTENV +The C library +.Xr putenv 3 +function. +Any registered hooks will run before the C library implementation. +The +.Fa hook_fn +field should +be a function that matches the following typedef: +.Bd -literal +typedef int (*sudo_hook_fn_putenv_t)(char *string, + void *closure); +.Ed +.Pp +If the registered hook does not match the typedef the results are +unspecified. +.El +.It Fa hook_fn +.Bd -literal -compact +sudo_hook_fn_t hook_fn; +.Ed +.Pp +The +.Fa hook_fn +field should be set to the plugin's hook implementation. +The actual function arguments will vary depending on the +.Fa hook_type +(see +.Fa hook_type +above). +In all cases, the +.Fa closure +field of +.Vt struct sudo_hook +is passed as the last function parameter. +This can be used to pass arbitrary data to the plugin's hook implementation. +.Pp +The function return value may be one of the following: +.Bl -tag -width 4n +.It Dv SUDO_HOOK_RET_ERROR +The hook function encountered an error. +.It Dv SUDO_HOOK_RET_NEXT +The hook completed without error, go on to the next hook (including +the system implementation if applicable). +For example, a +.Xr getenv 3 +hook might return +.Dv SUDO_HOOK_RET_NEXT +if the specified variable was not found in the private copy of the environment. +.It Dv SUDO_HOOK_RET_STOP +The hook completed without error, stop processing hooks for this invocation. +This can be used to replace the system implementation. +For example, a +.Fa setenv +hook that operates on a private copy of +the environment but leaves +.Va environ +unchanged. +.El +.El +.Pp +Care must be taken when hooking C library functions, +it is very easy to create an infinite loop. +For example, a +.Xr getenv 3 +hook that calls the +.Xr snprintf 3 +function may create a loop if the +.Xr snprintf 3 +implementation calls +.Xr getenv 3 +to check the locale. +To prevent this, you may wish to use a static variable in the hook +function to guard against nested calls. +For example: +.Bd -literal -offset indent +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; +.Ed +.Pp +.Em Hook API Version Macros +.Bd -literal +/* 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,\e + SUDO_HOOK_VERSION_MINOR) +.Ed +.Pp +For getters and setters see the +.Sx Policy plugin API . +.Ss Event API +When +.Nm sudo +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 +.Fn event_alloc +function. +.Pp +.Em Event structure +.Pp +Events are described by the following structure: +.Pp +.Bd -literal -compact +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); +}; +.Ed +.Pp +A +.Vt struct sudo_plugin_event +contains the following function pointers: +.Bl -tag -width 4n +.It Fa set +.Bd -literal -compact +int (*set)(struct sudo_plugin_event *pev, int fd, int events, + sudo_plugin_ev_callback_t callback, void *closure); +.Ed +.Pp +The +.Fn set +function takes the following arguments: +.Bl -tag -width 4n +.It Vt struct sudo_plugin_event * Ns Fa pev +A pointer to the +.Vt struct sudo_plugin_event +itself. +.It Fa fd +The file or socket descriptor for I/O-based events or the signal +number for signal events. +For time-based events, +.Fa fd +must be \-1. +.It Fa events +The following values determine what will trigger the event callback: +.Bl -tag -width 4n +.It Dv SUDO_PLUGIN_EV_TIMEOUT +callback is run after the specified timeout expires +.It Dv SUDO_PLUGIN_EV_READ +callback is run when the file descriptor is readable +.It Dv SUDO_PLUGIN_EV_WRITE +callback is run when the file descriptor is writable +.It Dv SUDO_PLUGIN_EV_PERSIST +event is persistent and remains enabled until explicitly deleted +.It Dv SUDO_PLUGIN_EV_SIGNAL +callback is run when the specified signal is received +.El +.Pp +The +.Dv SUDO_PLUGIN_EV_PERSIST +flag may be ORed with any of the event types. +It is also possible to OR +.Dv SUDO_PLUGIN_EV_READ +and +.Dv SUDO_PLUGIN_EV_WRITE +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. +.It Vt sudo_plugin_ev_callback_t Fa callback +.Bd -literal -compact +typedef void (*sudo_plugin_ev_callback_t)(int fd, int what, + void *closure); +.Ed +.Pp +The function to call when an event is triggered. +The +.Fn callback +function is run with the following arguments: +.Bl -tag -width 4n +.It Fa fd +The file or socket descriptor for I/O-based events or the signal +number for signal events. +.It Fa what +The event type that triggered that callback. +For events that have multiple event types (for example +.Dv SUDO_PLUGIN_EV_READ +and +.Dv SUDO_PLUGIN_EV_WRITE ) +or have an associated timeout, +.Fa what +can be used to determine why the callback was run. +.It Fa closure +The generic pointer that was specified in the +.Fn set +function. +.El +.It Fa closure +A generic pointer that will be passed to the callback function. +.El +.Pp +The +.Fn set +function returns 1 on success, and \-1 if a error occurred. +.It Fa add +.Bd -literal -compact +int (*add)(struct sudo_plugin_event *pev, struct timespec *timeout); +.Ed +.Pp +The +.Fn add +function adds the event +.Fa pev +to +.Nm sudo Ns No 's +event loop. +The event must have previously been initialized via the +.Fn set +function. +If the +.Fa timeout +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 +.Fa timeout +will be adjusted to match the new value, if any. +.Pp +The +.Fn add +function returns 1 on success, and \-1 if a error occurred. +.It Fa del +.Bd -literal -compact +int (*del)(struct sudo_plugin_event *pev); +.Ed +.Pp +The +.Fn del +function deletes the event +.Fa pev +from +.Nm sudo Ns No 's +event loop. +Deleted events can be added back via the +.Fn add +function. +.Pp +The +.Fn del +function returns 1 on success, and \-1 if a error occurred. +.It Fa pending +.Bd -literal -compact +int (*pending)(struct sudo_plugin_event *pev, int events, + struct timespec *ts); +.Ed +.Pp +The +.Fn pending +function can be used to determine whether one or more events is pending. +The +.Fa events +argument specifies which events to check for. +See the +.Fn set +function for a list of valid event types. +If +.Dv SUDO_PLUGIN_EV_TIMEOUT +is specified in +.Fa events , +the event has an associated timeout and the +.Fa ts +pointer is non-NULL, it will be filled in with the remaining time. +.It Fa fd +.Bd -literal -compact +int (*fd)(struct sudo_plugin_event *pev); +.Ed +.Pp +The +.Fn fd +function returns the descriptor or signal number associated with +the event +.Fa pev . +.It Fa setbase +.Bd -literal -compact +void (*setbase)(struct sudo_plugin_event *pev, void *base); +.Ed +.Pp +The +.Fn setbase +function sets the underlying event +.Fa base +for +.Fa pev +to the specified value. +This can be used to move an event created via +.Fn event_alloc +to a new event loop allocated by sudo's event subsystem. +If +.Fa base +is +.Dv NULL , +.Fa pev Ns 's +event base is reset to the default value, which corresponds to +.Nm sudo Ns 's +main event loop. +Using this function requires linking the plugin with the sudo_util +library. +It is unlikely to be used outside of the +.Nm sudoers +plugin. +.It Fa loopbreak +.Bd -literal -compact +void (*loopbreak)(struct sudo_plugin_event *pev); +.Ed +.Pp +The +.Fn loopbreak +function causes +.Nm sudo Ns No 's +event loop to exit immediately and the running command to be terminated. +.It Fa free +.Bd -literal -compact +void (*free)(struct sudo_plugin_event *pev); +.Ed +.Pp +The +.Fn free +function deletes the event +.Fa pev +from the event loop and frees the memory associated with it. +.El +.Ss Remote command execution +The +.Nm sudo +front-end does not support running remote commands. +However, starting with +.Nm sudo +1.8.8, the +.Fl h +option may be used to specify a remote host that is passed +to the policy plugin. +A plugin may also accept a +.Em runas_user +in the form of +.Dq user@hostname +which will work with older versions of +.Nm sudo . +It is anticipated that remote commands will be supported by executing a +.Dq helper +program. +The policy plugin should setup the execution environment such that the +.Nm sudo +front-end will run the helper which, in turn, will connect to the +remote host and run the command. +.Pp +For example, the policy plugin could utilize +.Nm ssh +to perform remote command execution. +The helper program would be responsible for running +.Nm ssh +with the proper options to use a private key or certificate +that the remote host will accept and run a program +on the remote host that would setup the execution environment +accordingly. +.Pp +Remote +.Nm sudoedit +functionality must be handled by the policy plugin, not +.Nm sudo +itself as the front-end has no knowledge that a remote command is +being executed. +This may be addressed in a future revision of the plugin API. +.Ss Conversation API +If the plugin needs to interact with the user, it may do so via the +.Fn conversation +function. +A plugin should not attempt to read directly from the standard input +or the user's terminal (neither of which are guaranteed to exist). +The caller must include a trailing newline in +.Fa msg +if one is to be printed. +.Pp +A +.Fn printf Ns -style +function is also available that can be used to display informational +or error messages to the user, which is usually more convenient for +simple messages where no use input is required. +.Pp +.Em Conversation function structures +.Pp +The conversation function takes as arguments pointers to the following +structures: +.Bd -literal +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; +}; +.Ed +.Pp +Pointers to the +.Fn conversation +and +.Fn printf Ns -style +functions are passed +in to the plugin's +.Fn open +function when the plugin is initialized. +The following type definitions can be used in the declaration of the +.Fn open +function: +.Bd -literal +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, ...); +.Ed +.Pp +To use the +.Fn conversation +function, the plugin must pass an array of +.Vt struct sudo_conv_message +and +.Vt struct sudo_conv_reply . +There must be a +.Vt struct sudo_conv_message +and +.Vt struct sudo_conv_reply +for each message in the conversation, that is, both arrays must +have the same number of elements. +Each +.Vt struct sudo_conv_reply +must have its +.Fa reply +member initialized to +.Dv NULL . +The +.Vt struct sudo_conv_callback +pointer, if not +.Dv NULL , +should contain function pointers to be called when the +.Nm sudo +process is suspended and/or resumed during conversation input. +The +.Fa on_suspend +and +.Fa on_resume +functions are called with the signal that caused +.Nm sudo +to be suspended and the +.Fa closure +pointer from the +.Vt struct sudo_conv_callback . +These functions should return 0 on success and \-1 on error. +On error, the conversation will end and the conversation function +will return a value of \-1. +The intended use is to allow the plugin to release resources, such as locks, +that should not be held indefinitely while suspended and then reacquire them +when the process is resumed. +The functions are not actually invoked from within a signal handler. +.Pp +The +.Fa msg_type +must be set to one of the following values: +.Bl -tag -width 4n +.It Dv SUDO_CONV_PROMPT_ECHO_OFF +Prompt the user for input with echo disabled; +this is generally used for passwords. +The reply will be stored in the +.Fa replies +array, and it will never be +.Dv NULL . +.It Dv SUDO_CONV_PROMPT_ECHO_ON +Prompt the user for input with echo enabled. +The reply will be stored in the +.Fa replies +array, and it will never be +.Dv NULL . +.It Dv SUDO_CONV_ERROR_MSG +Display an error message. +The message is written to the standard error unless the +.Dv SUDO_CONV_PREFER_TTY +flag is set, in which case it is written to the user's terminal if possible. +.It Dv SUDO_CONV_INFO_MSG +Display a message. +The message is written to the standard output unless the +.Dv SUDO_CONV_PREFER_TTY +flag is set, in which case it is written to the user's terminal if possible. +.It Dv SUDO_CONV_PROMPT_MASK +Prompt the user for input but echo an asterisk character for each +character read. +The reply will be stored in the +.Fa replies +array, and it will never be +.Dv NULL . +This can be used to provide visual feedback to the user while reading +sensitive information that should not be displayed. +.El +.Pp +In addition to the above values, the following flag bits may also be set: +.Bl -tag -width 4n +.It Dv SUDO_CONV_PROMPT_ECHO_OK +Allow input to be read when echo cannot be disabled +when the message type is +.Dv SUDO_CONV_PROMPT_ECHO_OFF +or +.Dv SUDO_CONV_PROMPT_MASK . +By default, +.Nm sudo +will refuse to read input if the echo cannot be disabled for those +message types. +.It Dv SUDO_CONV_PREFER_TTY +When displaying a message via +.Dv SUDO_CONV_ERROR_MSG +or +.Dv SUDO_CONV_INFO_MSG , +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 +.Dv SUDO_CONV_ERROR_MSG +or +.Dv SUDO_CONV_INFO_MSG +was used. +The user's terminal is always used when possible for input, +this flag is only used for output. +.El +.Pp +The +.Fa timeout +in seconds until the prompt will wait for no more input. +A zero value implies an infinite timeout. +.Pp +The plugin is responsible for freeing the reply buffer located in each +.Vt struct sudo_conv_reply , +if it is not +.Dv NULL . +.Dv SUDO_CONV_REPL_MAX +represents the maximum length of the reply buffer (not including +the trailing NUL character). +In practical terms, this is the longest password +.Nm sudo +will support. +.Pp +The +.Fn printf Ns -style +function uses the same underlying mechanism as the +.Fn conversation +function but only supports +.Dv SUDO_CONV_INFO_MSG +and +.Dv SUDO_CONV_ERROR_MSG +for the +.Fa msg_type +parameter. +It can be more convenient than using the +.Fn conversation +function if no user reply is needed and supports standard +.Fn printf +escape sequences. +.Pp +See the sample plugin for an example of the +.Fn conversation +function usage. +.Ss Plugin invocation order +As of +.Nm sudo +1.9.0, the plugin +.Fn open +and +.Fn close +functions are called in the +following order: +.Bl -enum +.It +audit open +.It +policy open +.It +approval open +.It +approval close +.It +I/O log open +.It +command runs +.It +command exits +.It +I/O log close +.It +policy close +.It +audit close +.It +sudo exits +.El +.Pp +Prior to +.Nm sudo +1.9.0, the I/O log +.Fn close +function was called +.Em after +the policy +.Fn close +function. +.Ss Sudoers group plugin API +The +.Nm sudoers +plugin supports its own plugin interface to allow non-Unix +group lookups. +This can be used to query a group source other than the standard Unix +group database. +Two sample group plugins are bundled with +.Nm sudo , +.Em group_file , +and +.Em system_group , +are detailed in +.Xr sudoers @mansectform@ . +Third party group plugins include a QAS AD plugin available from Quest Software. +.Pp +A group plugin must declare and populate a +.Vt struct sudoers_group_plugin +in the global scope. +This structure contains pointers to the functions that implement plugin +initialization, cleanup, and group lookup. +.Bd -literal +struct sudoers_group_plugin { + unsigned int version; + int (*init)(int version, sudo_printf_t sudo_plugin_printf, + char *const argv[]); + void (*cleanup)(void); + int (*query)(const char *user, const char *group, + const struct passwd *pwd); +}; +.Ed +.Pp +A +.Vt struct sudoers_group_plugin +has the following fields: +.Bl -tag -width 4n +.It Fa version +The +.Fa version +field should be set to GROUP_API_VERSION. +.Pp +This allows +.Nm sudoers +to determine the API version the group plugin +was built against. +.It Fa init +.Bd -literal -compact +int (*init)(int version, sudo_printf_t sudo_plugin_printf, + char *const argv[]); +.Ed +.Pp +The +.Fn init +function is called after +.Em sudoers +has been parsed but +before any policy checks. +It returns 1 on success, 0 on failure (or if the plugin is not configured), +and \-1 if a error occurred. +If an error occurs, the plugin may call the +.Fn plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional error information to the user. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa version +The version passed in by +.Nm sudoers +allows the plugin to determine the +major and minor version number of the group plugin API supported by +.Nm sudoers . +.It Fa plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used to display informational or error message to the user. +Returns the number of characters printed on success and \-1 on failure. +.It Fa argv +A +.Dv NULL Ns -terminated +array of arguments generated from the +.Em group_plugin +option in +.Em sudoers . +If no arguments were given, +.Fa argv +will be +.Dv NULL . +.El +.It Fa cleanup +.Bd -literal -compact +void (*cleanup)(); +.Ed +.Pp +The +.Fn cleanup +function is called when +.Nm sudoers +has finished its +group checks. +The plugin should free any memory it has allocated and close open file handles. +.It Fa query +.Bd -literal -compact +int (*query)(const char *user, const char *group, + const struct passwd *pwd); +.Ed +.Pp +The +.Fn query +function is used to ask the group plugin whether +.Fa user +is a member of +.Fa group . +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It Fa user +The name of the user being looked up in the external group database. +.It Fa group +The name of the group being queried. +.It Fa pwd +The password database entry for +.Fa user , +if any. +If +.Fa user +is not +present in the password database, +.Fa pwd +will be +.Dv NULL . +.El +.El +.Pp +.Em Group API Version Macros +.Bd -literal +/* 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) | \e + GROUP_API_VERSION_MINOR) +.Ed +For getters and setters see the +.Sx Policy plugin API . +.Sh PLUGIN API CHANGELOG +The following revisions have been made to the Sudo Plugin API. +.Bl -tag -width 4n +.It Version 1.0 +Initial API version. +.It Version 1.1 (sudo 1.8.0) +The I/O logging plugin's +.Fn open +function was modified to take the +.Fa command_info +list as an argument. +.It Version 1.2 (sudo 1.8.5) +The Policy and I/O logging plugins' +.Fn open +functions are now passed +a list of plugin parameters if any are specified in +.Xr sudo.conf @mansectform@ . +.Pp +A simple hooks API has been introduced to allow plugins to hook in to the +system's environment handling functions. +.Pp +The +.Fn init_session +Policy plugin function is now passed a pointer +to the user environment which can be updated as needed. +This can be used to merge in environment variables stored in the PAM +handle before a command is run. +.It Version 1.3 (sudo 1.8.7) +Support for the +.Em exec_background +entry has been added to the +.Fa command_info +list. +.Pp +The +.Em max_groups +and +.Em plugin_dir +entries were added to the +.Fa settings +list. +.Pp +The +.Fn version +and +.Fn close +functions are now optional. +Previously, a missing +.Fn version +or +.Fn close +function would result in a crash. +If no policy plugin +.Fn close +function is defined, a default +.Fn close +function will be provided by the +.Nm sudo +front-end that displays a warning if the command could not be +executed. +.Pp +The +.Nm sudo +front-end now installs default signal handlers to trap common signals +while the plugin functions are run. +.It Version 1.4 (sudo 1.8.8) +The +.Em remote_host +entry was added to the +.Fa settings +list. +.It Version 1.5 (sudo 1.8.9) +The +.Em preserve_fds +entry was added to the +.Fa command_info +list. +.It Version 1.6 (sudo 1.8.11) +The behavior when an I/O logging plugin returns an error +.Pq \-1 +has changed. +Previously, the +.Nm sudo +front-end took no action when the +.Fn log_ttyin , +.Fn log_ttyout , +.Fn log_stdin , +.Fn log_stdout , +or +.Fn log_stderr +function returned an error. +.Pp +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. +.It Version 1.7 (sudo 1.8.12) +The +.Em plugin_path +entry was added to the +.Fa settings +list. +.Pp +The +.Em debug_flags +entry now starts with a debug file path name and may occur multiple +times if there are multiple plugin-specific Debug lines in the +.Xr sudo.conf @mansectform@ file. +.It Version 1.8 (sudo 1.8.15) +The +.Em sudoedit_checkdir +and +.Em sudoedit_follow +entries were added to the +.Fa command_info +list. +The default value of +.Em sudoedit_checkdir +was changed to true in sudo 1.8.16. +.Pp +The sudo +.Fn conversation +function now takes a pointer to a +.Vt struct sudo_conv_callback +as its fourth argument. +The +.Vt sudo_conv_t +definition has been updated to match. +The plugin must specify that it supports plugin API version 1.8 or higher +to receive a conversation function pointer that supports this argument. +.It Version 1.9 (sudo 1.8.16) +The +.Em execfd +entry was added to the +.Fa command_info +list. +.It Version 1.10 (sudo 1.8.19) +The +.Em umask +entry was added to the +.Fa user_info +list. +The +.Em iolog_group , +.Em iolog_mode , +and +.Em iolog_user +entries were added to the +.Fa command_info +list. +.It Version 1.11 (sudo 1.8.20) +The +.Em timeout +entry was added to the +.Fa settings +list. +.It Version 1.12 (sudo 1.8.21) +The +.Fn change_winsize +function was added to +.Vt struct io_plugin . +.It Version 1.13 (sudo 1.8.26) +The +.Fn log_suspend +function was added to +.Vt struct io_plugin . +.It Version 1.14 (sudo 1.8.29) +The +.Em umask_override +entry was added to the +.Fa command_info +list. +.It Version 1.15 (sudo 1.9.0) +The +.Em cwd_optional +entry was added to the +.Fa command_info +list. +.Pp +The +.Fn event_alloc +function was added to +.Vt struct policy_plugin +and +.Vt struct io_plugin . +.Pp +The +.Fa errstr +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. +.Pp +The +.Fn close +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. +.Pp +.Dv SUDO_CONV_REPL_MAX +has increased from 255 to 1023 bytes. +.Pp +Support for audit and approval plugins was added. +.It Version 1.16 (sudo 1.9.3) +Initial resource limit values were added to the +.Fa user_info +list. +.Pp +The +.Em cmnd_chroot +and +.Em cmnd_cwd +entries were added to the +.Fa settings +list. +.It Version 1.17 (sudo 1.9.4) +The +.Fn event_alloc +function was added to +.Vt struct audit_plugin +and +.Vt struct approval_plugin . +.It Version 1.18 (sudo 1.9.9) +The policy may now set resource limit values in the +.Fa command_info +list. +The +.Em intercept +and +.Em log_subcmds +entries were added to the +.Fa command_info +list. +.It Version 1.19 (sudo 1.9.11) +The +.Em intercept_ptrace +and +.Em intercept_setid +entries were added to the +.Fa settings +list. +The +.Em apparmor_profile +and +.Em use_ptrace +entries were added to the +.Fa command_info +list. +.It Version 1.20 (sudo 1.9.12) +The +.Em update_ticket +entry was added to the +.Fa settings +list. +The +.Em intercept_verify +entry was added to the +.Fa command_info +list. +.It Version 1.21 (sudo 1.9.13) +The +.Em sudoedit_nfiles +entry was added to the +.Fa command_info +list. +.El +.Sh SEE ALSO +.Xr sudo.conf @mansectform@ , +.Xr sudoers @mansectform@ , +.Xr sudo @mansectsu@ +.Sh AUTHORS +Many people have worked on +.Nm sudo +over the years; this version consists of code written primarily by: +.Bd -ragged -offset indent +.An Todd C. Miller +.Ed +.Pp +See the CONTRIBUTORS.md file in the +.Nm sudo +distribution (https://www.sudo.ws/about/contributors/) for an +exhaustive list of people who have contributed to +.Nm sudo . +.Sh BUGS +If you believe you have found a bug in +.Nm sudo , +you can submit a bug report at https://bugzilla.sudo.ws/ +.Sh 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. +.Sh DISCLAIMER +.Nm sudo +is provided +.Dq 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 +.Nm sudo +or https://www.sudo.ws/about/license/ for complete details. |