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diff --git a/doc/sudo_plugin.mdoc.in b/doc/sudo_plugin.mdoc.in new file mode 100644 index 0000000..a293ee3 --- /dev/null +++ b/doc/sudo_plugin.mdoc.in @@ -0,0 +1,2625 @@ +.\" +.\" Copyright (c) 2009-2018 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 October 24, 2018 +.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 +policy plugin and an associated I/O logging plugin are used. +Via the plugin API, +.Nm sudo +can be configured to use alternate policy and/or I/O logging plugins +provided by third parties. +The plugins to be used are specified in the +.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 +.Li sudo_plugin.h +header file. +.Ss Policy plugin API +A policy plugin must declare and populate a +.Li policy_plugin +struct 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 plugin_printf, char * const settings[], + char * const user_info[], char * const user_env[], + char * const plugin_options[]); + void (*close)(int exit_status, int error); + int (*show_version)(int verbose); + int (*check_policy)(int argc, char * const argv[], + char *env_add[], char **command_info[], + char **argv_out[], char **user_env_out[]); + int (*list)(int argc, char * const argv[], int verbose, + const char *list_user); + int (*validate)(void); + void (*invalidate)(int remove); + int (*init_session)(struct passwd *pwd, char **user_env[]); + void (*register_hooks)(int version, + int (*register_hook)(struct sudo_hook *hook)); + void (*deregister_hooks)(int version, + int (*deregister_hook)(struct sudo_hook *hook)); +}; +.Ed +.Pp +The policy_plugin struct has the following fields: +.Bl -tag -width 4n +.It type +The +.Li type +field should always be set to SUDO_POLICY_PLUGIN. +.It version +The +.Li 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 open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t plugin_printf, char * const settings[], + char * const user_info[], char * const user_env[], + char * const plugin_options[]); +.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 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 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 conversation +A pointer to the +.Fn conversation +function that can be used by the plugin to interact with the user (see below). +Returns 0 on success and \-1 on failure. +.It plugin_printf +A pointer to a +.Fn printf Ns -style +function that may be used to display informational or error messages +(see below). +Returns the number of characters printed on success and \-1 on failure. +.It 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 flags the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding flag has +been specified on the command line. +.Pp +When parsing +.Em 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. +.Bl -tag -width 4n +.It bsdauth_type=string +Authentication type, if specified by the +.Fl a +flag, to use on +systems where +.Bx +authentication is supported. +.It closefrom=number +If specified, the user has requested via the +.Fl C +flag 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 +.Em command_info +list. +.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 +.Li 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 +.Li Debug +entry. +.It debug_level=number +This setting has been deprecated in favor of +.Em debug_flags . +.It ignore_ticket=bool +Set to true if the user specified the +.Fl k +flag 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 +.It login_class=string +.Bx +login class to use when setting resource limits and nice value, +if specified by the +.Fl c +flag. +.It login_shell=bool +Set to true if the user specified the +.Fl i +flag, 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 +flag, 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 +flag, indicating that +the user wishes to preserve the environment. +.It preserve_groups=bool +Set to true if the user specified the +.Fl P +flag, 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 +flag. +.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 +flag, indicating that the user wishes to run a shell. +.It runas_group=string +The group name or gid to run the command as, if specified via +the +.Fl g +flag. +.It runas_user=string +The user name or uid to run the command as, if specified via the +.Fl u +flag. +.It selinux_role=string +SELinux role to use when executing the command, if specified by +the +.Fl r +flag. +.It selinux_type=string +SELinux type to use when executing the command, if specified by +the +.Fl t +flag. +.It set_home=bool +Set to true if the user specified the +.Fl H +flag. +If true, set the +.Li HOME +environment variable to the target user's home directory. +.It sudoedit=bool +Set to true when the +.Fl e +flag is specified or if invoked as +.Nm sudoedit . +The plugin shall substitute an editor into +.Em 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 +.Em check_policy +section. +.It timeout=string +User-specified command timeout. +Not all plugins support command timeouts and the ability for the +user to set a timeout may be restricted by policy. +The format of the timeout string is plugin-specific. +.El +.Pp +Additional settings may be added in the future so the plugin should +silently ignore settings that it does not recognize. +.It 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 +.Em 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. +.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 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, +.Em plugin_options +will be the +.Dv NULL +pointer. +.Pp +NOTE: the +.Em 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 +.Em plugin_options . +Failure to do so may result in a crash. +.It ppid=int +The parent process ID of the running +.Nm sudo +process. +Only available starting with API version 1.2. +.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 \-1 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 +.Dq Li 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 user_env +The user's environment in the form of a +.Dv NULL Ns -terminated vector of +.Dq name=value +strings. +.Pp +When parsing +.Em 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. +.El +.It close +.Bd -literal -compact +void (*close)(int exit_status, int error); +.Ed +.Pp +The +.Fn close +function is called when the command being run by +.Nm sudo +finishes. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It exit_status +The command's exit status, as returned by the +.Xr wait 2 +system call. +The value of +.Li exit_status +is undefined if +.Li error +is non-zero. +.It error +If the command could not be executed, this is set to the value of +.Li errno +set by the +.Xr execve 2 +system call. +The plugin is responsible for displaying error information via the +.Fn conversation +or +.Fn plugin_printf +function. +If the command was successfully executed, the value of +.Li error +is 0. +.El +.Pp +If no +.Fn close +function is defined, no I/O logging plugins are loaded, +and neither the +.Em timeout +not +.Em use_pty +options are set in the +.Li command_info +list, the +.Nm sudo +front end may execute the command directly instead of running +it as a child process. +.It 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 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[]); +.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 +.Em 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 should choose the editor to be used, potentially from a variable +in the user's environment, such as +.Li EDITOR , +and include it in +.Em argv_out +(note that environment +variables may include command line flags). +The files to be edited should be copied from +.Em argv +into +.Em argv_out , +separated from the +editor and its arguments by a +.Dq Li -- +element. +The +.Dq Li -- +will +be removed by +.Nm sudo +before the editor is executed. +The plugin should also set +.Em sudoedit=true +in the +.Em command_info +list. +.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 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 argc +The number of elements in +.Em argv , +not counting the final +.Dv NULL +pointer. +.It 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 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 +.Em 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 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 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. +.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 pty (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 +.Em sudo +behavior or when the command is not being run in a pty. +.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 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 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 +.Li runas_user . +.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_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 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-tty is allocated. +By default, the new entry will be a copy of the user's existing utmp +entry (if any), with the tty, time, type and pid fields updated. +.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_follow +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 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. +.It use_pty=bool +Allocate a pseudo-tty to run the command in, regardless of whether +or not I/O logging is in use. +By default, +.Nm sudo +will only run +the command in a pty 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 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 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. +.El +.It list +.Bd -literal -compact +int (*list)(int argc, char * const argv[], + int verbose, const char *list_user); +.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 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 plugin_printf +function using +.Dv SUDO_CONV_INFO_MSG , +.Bl -tag -width 4n +.It verbose +Flag indicating whether to list in verbose mode or not. +.It list_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 argc +The number of elements in +.Em argv , +not counting the final +.Dv NULL +pointer. +.It 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. +.El +.It validate +.Bd -literal -compact +int (*validate)(void); +.Ed +.Pp +The +.Fn validate +function is called when +.Nm sudo +is run with the +.Fl v +flag. +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 plugin_printf +function with +.Dv SUDO_CONF_ERROR_MSG +to present additional +error information to the user. +.It invalidate +.Bd -literal -compact +void (*invalidate)(int remove); +.Ed +.Pp +The +.Fn invalidate +function is called when +.Nm sudo +is called with +the +.Fl k +or +.Fl K +flag. +For policy plugins such as +.Nm sudoers +that +cache authentication credentials, this function will invalidate the +credentials. +If the +.Em remove +flag is set, 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 init_session +.Bd -literal -compact +int (*init_session)(struct passwd *pwd, char **user_envp[); +.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 and before any uid or gid changes. +This can be used to perform session setup that is not supported by +.Em command_info , +such as opening the PAM session. +The +.Fn close +function can be +used to tear down the session that was opened by +.Li init_session . +.Pp +The +.Em pwd +argument points to a passwd struct for the user the +command will be run as if the uid the command will run as was found +in the password database, otherwise it will be +.Dv NULL . +.Pp +The +.Em user_env +argument points to the environment the command will +run in, in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +This is the same string passed back to the front end via +the Policy Plugin's +.Em user_env_out +parameter. +If the +.Fn init_session +function needs to modify the user environment, it should update the +pointer stored in +.Em user_env . +The expected use case is to merge the contents of the PAM environment +(if any) with the contents of +.Em user_env . +NOTE: the +.Em user_env +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 +.Em user_env . +Failure to do so may result in a crash. +.Pp +Returns 1 on success, 0 on failure and \-1 on error. +On error, 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. +.It 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, +.Li register_hooks +should be set to the +.Dv NULL +pointer. +.Pp +The +.Em 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 +.Li struct 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 +NOTE: 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, +.Li register_hooks +will not be called. +.It 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, +.Li deregister_hooks +should be set to the +.Dv NULL +pointer. +.Pp +The +.Em 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, +.Li deregister_hook +will return an error. +.Pp +See the +.Sx Hook function API +section below for more information +about hooks. +.Pp +NOTE: 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, +.Li deregister_hooks +will not be called. +.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 plugin_printf, char * const settings[], + char * const user_info[], char * const command_info[], + int argc, char * const argv[], char * const user_env[], + char * const plugin_options[]); + void (*close)(int exit_status, int error); /* wait status or error */ + int (*show_version)(int verbose); + int (*log_ttyin)(const char *buf, unsigned int len); + int (*log_ttyout)(const char *buf, unsigned int len); + int (*log_stdin)(const char *buf, unsigned int len); + int (*log_stdout)(const char *buf, unsigned int len); + int (*log_stderr)(const char *buf, unsigned int len); + void (*register_hooks)(int version, + int (*register_hook)(struct sudo_hook *hook)); + void (*deregister_hooks)(int version, + int (*deregister_hook)(struct sudo_hook *hook)); + int (*change_winsize)(unsigned int lines, unsigned int cols); + int (*log_suspend)(int signo); +}; +.Ed +.Pp +When an I/O plugin is loaded, +.Nm sudo +runs the command in a pseudo-tty. +This makes it possible to log the input and output from the user's +session. +If any of the standard input, standard output or standard error do not +correspond to a tty, +.Nm sudo +will open a pipe to capture +the I/O for logging before passing it on. +.Pp +The log_ttyin function receives the raw user input from the terminal +device (note that this will include input even when echo is disabled, +such as when a password is read). +The log_ttyout function receives output from the pseudo-tty that is +suitable for replaying the user's session at a later time. +The +.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 +The io_plugin struct has the following fields: +.Bl -tag -width 4n +.It type +The +.Li type +field should always be set to +.Dv SUDO_IO_PLUGIN . +.It version +The +.Li 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 open +.Bd -literal -compact +int (*open)(unsigned int version, sudo_conv_t conversation, + sudo_printf_t plugin_printf, char * const settings[], + char * const user_info[], char * const command_info[], + int argc, char * const argv[], char * const user_env[], + char * const plugin_options[]); +.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 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 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 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 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 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 flags the user specified when running +.Nm sudo . +As such, they will only be present when the corresponding flag has +been specified on the command line. +.Pp +When parsing +.Em 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 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 +.Em 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 argc +The number of elements in +.Em argv , +not counting the final +.Dv NULL +pointer. +It can be zero, when +.Nm sudo +is called with +.Fl V . +.It 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 user_env +The user's environment in the form of a +.Dv NULL Ns -terminated +vector of +.Dq name=value +strings. +.Pp +When parsing +.Em 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 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, +.Em plugin_options +will be the +.Dv NULL +pointer. +.Pp +NOTE: the +.Em 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 +.Em plugin_options . +Failure to do so may result in a crash. +.El +.It close +.Bd -literal -compact +void (*close)(int exit_status, int error); +.Ed +.Pp +The +.Fn close +function is called when the command being run by +.Nm sudo +finishes. +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It exit_status +The command's exit status, as returned by the +.Xr wait 2 +system call. +The value of +.Li exit_status +is undefined if +.Li error +is non-zero. +.It error +If the command could not be executed, this is set to the value of +.Li errno +set by the +.Xr execve 2 +system call. +If the command was successfully executed, the value of +.Li error +is 0. +.El +.It 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 log_ttyin +.Bd -literal -compact +int (*log_ttyin)(const char *buf, unsigned int len); +.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 buf +The buffer containing user input. +.It len +The length of +.Em buf +in bytes. +.El +.It log_ttyout +.Bd -literal -compact +int (*log_ttyout)(const char *buf, unsigned int len); +.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 buf +The buffer containing command output. +.It len +The length of +.Em buf +in bytes. +.El +.It log_stdin +.Bd -literal -compact +int (*log_stdin)(const char *buf, unsigned int len); +.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 buf +The buffer containing user input. +.It len +The length of +.Em buf +in bytes. +.El +.It log_stdout +.Bd -literal -compact +int (*log_stdout)(const char *buf, unsigned int len); +.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 buf +The buffer containing command output. +.It len +The length of +.Em buf +in bytes. +.El +.It log_stderr +.Bd -literal -compact +int (*log_stderr)(const char *buf, unsigned int len); +.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 buf +The buffer containing command output. +.It len +The length of +.Em buf +in bytes. +.El +.It register_hooks +See the +.Sx Policy plugin API +section for a description of +.Li register_hooks . +.It deregister_hooks +See the +.Sx Policy plugin API +section for a description of +.Li deregister_hooks . +.It change_winsize +.Bd -literal -compact +int (*change_winsize)(unsigned int lines, unsigned int cols); +.Ed +.Pp +The +.Fn change_winsize +function is called whenever the window size of the terminal changes from +the initial values specified in the +.Li user_info +list. +Returns \-1 if an error occurred, in which case no further calls to +.Fn change_winsize +will be made, +.It log_suspend +.Bd -literal -compact +int (*log_suspend)(int signo); +.Ed +.Pp +The +.Fn log_suspend +function is called whenever a command is suspended or resumed. +The +.Fa signo +argument is either the signal that caused the command to be suspended or +.Dv SIGCONT +if the command was 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, +.El +.Pp +.Em I/O Plugin Version Macros +.Pp +Same as for the +.Sx Policy plugin API . +.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 +.Ev 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 +The +.Li sudo_hook +structure has the following fields: +.Bl -tag -width 4n +.It hook_version +The +.Li hook_version +field should be set to +.Dv SUDO_HOOK_VERSION . +.It hook_type +The +.Li 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 +.Li 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 +.Li 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 +.Li 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 +.Li 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 hook_fn +sudo_hook_fn_t hook_fn; +.Pp +The +.Li hook_fn +field should be set to the plugin's hook implementation. +The actual function arguments will vary depending on the +.Li hook_type +(see +.Li hook_type +above). +In all cases, the +.Li closure +field of +.Li 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 native 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 native implementation. +For example, a +.Li setenv +hook that operates on a private copy of +the environment but leaves +.Li environ +unchanged. +.El +.El +.Pp +Note that it is very easy to create an infinite loop when hooking +C library functions. +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 +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 Remote command execution +The +.Nm sudo +front end does not have native support for 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 +Note that 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 tty (neither of which are guaranteed to exist). +The caller must include a trailing newline in +.Li 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 255 + +struct sudo_conv_reply { + char *reply; +}; + +typedef int (*sudo_conv_callback_fn_t)(int signo, void *closure); +struct sudo_conv_callback { + unsigned int version; + void *closure; + sudo_conv_callback_fn_t on_suspend; + sudo_conv_callback_fn_t on_resume; +}; +.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 +.Li sudo_conv_message +and +.Li sudo_conv_reply +structures. +There must be a +.Li struct sudo_conv_message +and +.Li struct sudo_conv_reply +for +each message in the conversation, that is, both arrays must have the same +number of elements. +Each +.Li struct sudo_conv_reply +must have its +.Em reply +member initialized to +.Dv NULL . +The +.Li 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 +.Li struct sudo_conv_callback . +These functions should return 0 on success and \-1 on error. +On error, the conversation will end and the conversation function +will return a value of \-1. +The intended use is to allow the plugin to release resources, such as locks, +that should not be held indefinitely while suspended and then reacquire them +when the process is resumed. +Note that the functions are not actually invoked from within a signal handler. +.Pp +The +.Em msg_type +must be set to one of the following values: +.Bl -tag -width 4n +.It 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 +.Em replies +array, and it will never be +.Dv NULL . +.It SUDO_CONV_PROMPT_ECHO_ON +Prompt the user for input with echo enabled. +The reply will be stored in the +.Em replies +array, and it will never be +.Dv NULL . +.It 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 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 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 +.Em 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 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 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 +The user's terminal is always used when possible for input, +this flag is only used for output. +.Dv SUDO_CONV_ERROR_MSG +or +.Dv SUDO_CONV_INFO_MSG +was used. +.El +.Pp +The +.Em 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 +.Li 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. +It is also useful as a maximum value for the +.Fn memset_s +function when clearing passwords filled in by the conversation function. +.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 +.Em 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 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 +.Li sudoers_group_plugin +struct 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_printf, + char *const argv[]); + void (*cleanup)(void); + int (*query)(const char *user, const char *group, + const struct passwd *pwd); +}; +.Ed +.Pp +The +.Li sudoers_group_plugin +struct has the following fields: +.Bl -tag -width 4n +.It version +The +.Li 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 init +.Bd -literal -compact +int (*init)(int version, sudo_printf_t 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 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 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 argv +A +.Dv NULL Ns -terminated +array of arguments generated from the +.Em group_plugin +option in +.Em sudoers . +If no arguments were given, +.Em argv +will be +.Dv NULL . +.El +.It 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 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 +.Em user +is a member of +.Em group . +.Pp +The function arguments are as follows: +.Bl -tag -width 4n +.It user +The name of the user being looked up in the external group database. +.It group +The name of the group being queried. +.It pwd +The password database entry for +.Em user , +if any. +If +.Em user +is not +present in the password database, +.Em 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 +.Li 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 +.Li 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 +.Li command_info +list. +.Pp +The +.Em max_groups +and +.Em plugin_dir +entries were added to the +.Li 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 +.Li settings +list. +.It Version 1.5 (sudo 1.8.9) +The +.Em preserve_fds +entry was added to the +.Li 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 +.Li 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 +.Li command_info +list. +The default value of +.Em sudoedit_checkdir +was changed to true in sudo 1.8.16. +.Pp +The sudo +.Em conversation +function now takes a pointer to a +.Li struct sudo_conv_callback +as its fourth argument. +The +.Li 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 +.Li command_info +list. +.It Version 1.10 (sudo 1.8.19) +The +.Em umask +entry was added to the +.Li user_info +list. +The +.Em iolog_group , +.Em iolog_mode , +and +.Em iolog_user +entries were added to the +.Li command_info +list. +.It Version 1.11 (sudo 1.8.20) +The +.Em timeout +entry was added to the +.Li settings +list. +.It Version 1.12 (sudo 1.8.21) +The +.Li change_winsize +field was added to the io_plugin struct. +.It Version 1.13 (sudo 1.8.26) +The +.Li log_suspend +field was added to the io_plugin struct. +.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 file in the +.Nm sudo +distribution (https://www.sudo.ws/contributors.html) for an +exhaustive list of people who have contributed to +.Nm sudo . +.Sh BUGS +If you feel you have found a bug in +.Nm sudo , +please 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 file distributed with +.Nm sudo +or https://www.sudo.ws/license.html for complete details. |