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fa717176b295191b944bb159cb870704e1119d16
sudo/doc/sudo_plugin.man.in
Todd C. Miller fa717176b2 Remove check_sudoedit function pointer in struct sudo_policy. 
Instead, sudo will set sudoedit=true in the settings array.
The plugin should check for this and modify argv_out as appropriate
in check_policy.
2010-05-17 10:25:27 -04:00

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.\" Copyright (c) 2009-2010 Todd C. Miller <Todd.Miller@courtesan.com>
.\"
.\" 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.
.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
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.\" ========================================================================
.\"
.IX Title "SUDO_PLUGIN @mansectsu@"
.TH SUDO_PLUGIN @mansectsu@ "May 17, 2010" "1.8.0a1" "MAINTENANCE COMMANDS"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "Sudo Plugin API"
.IX Header "Sudo Plugin API"
Starting with version 1.8, \fBsudo\fR supports a plugin \s-1API\s0
for policy and session logging. By default, the \fIsudoers\fR policy
plugin and an associated I/O logging plugin are used. Via the plugin
\&\s-1API\s0, \fBsudo\fR can be configured to use alternate policy and/or I/O
logging plugins provided by third parties. The plugins to be used
are specified via the \fI/etc/sudo.conf\fR file.
.PP
The \s-1API\s0 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 \s-1API\s0 is defined by the \f(CW\*(C`sudo_plugin.h\*(C'\fR header file.
.SS "The sudo.conf File"
.IX Subsection "The sudo.conf File"
The \fI/etc/sudo.conf\fR file contains plugin configuration directives.
Currently, the only supported keyword is the \f(CW\*(C`Plugin\*(C'\fR directive,
which causes a plugin plugin to be loaded.
.PP
A \f(CW\*(C`Plugin\*(C'\fR line consists of the \f(CW\*(C`Plugin\*(C'\fR keyword, followed by the
\&\fIsymbol_name\fR and the \fIpath\fR to the shared object containing the
plugin. The \fIsymbol_name\fR is the name of the \f(CW\*(C`struct policy_plugin\*(C'\fR
or \f(CW\*(C`struct io_plugin\*(C'\fR in the plugin shared object. The \fIpath\fR
may be fully qualified or relative. If not fully qualified it is
relative to the \f(CW$prefix\fR/libexec directory where the prefix is
specified at build time (/usr/local by default).
.PP
The same shared object may contain multiple plugins, each with a
different symbol name. The shared object file must be owned by uid
0 and only writable by its owner. Because of ambiguities that arise
from composite policies, only a single policy plugin may be specified.
This limitation does not apply to I/O plugins.
.PP
.Vb 12
\& #
\& # Default /etc/sudo.conf file
\& #
\& # Format:
\& # Plugin plugin_name plugin_path
\& #
\& # The plugin_path relative to prefix/libexec unless fully qualified
\& # The plugin_name corresponds to a global symbol in the plugin
\& # that contains the plugin interface.
\& #
\& Plugin policy_plugin sudoers.so
\& Plugin io_plugin sudoers.so
.Ve
.SS "Policy Plugin \s-1API\s0"
.IX Subsection "Policy Plugin API"
A policy plugin must declare and populate a \f(CW\*(C`policy_plugin\*(C'\fR struct
in the global scope. This structure contains pointers to the functions
that implement the \fBsudo\fR policy checks. The name of the symbol should
be specified in \fI/etc/sudo.conf\fR along with a path to the plugin
so that \fBsudo\fR can load it.
.PP
.Vb 10
\& 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[]);
\& 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);
\& };
.Ve
.PP
The policy_plugin struct has the following fields:
.IP "type" 4
.IX Item "type"
The \f(CW\*(C`type\*(C'\fR field should always be set to \s-1SUDO_POLICY_PLUGIN\s0
.IP "version" 4
.IX Item "version"
The \f(CW\*(C`version\*(C'\fR field should be set to \s-1SUDO_API_VERSION\s0.
.Sp
This allows \fBsudo\fR to determine the \s-1API\s0 version the plugin was
built against.
.IP "open" 4
.IX Item "open"
.Vb 3
\& 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[]);
.Ve
.Sp
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, \fBsudo\fR will
print a usage message before it exits. If an error occurs, the
plugin may optionally call the conversation or plugin_printf function
with \f(CW\*(C`SUDO_CONF_ERROR_MSG\*(C'\fR to present additional error information
to the user.
.Sp
The function arguments are as follows:
.RS 4
.IP "version" 4
.IX Item "version"
The version passed in by \fBsudo\fR allows the plugin to determine the
major and minor version number of the plugin \s-1API\s0 supported by
\&\fBsudo\fR.
.IP "conversation" 4
.IX Item "conversation"
A pointer to the conversation function that can be used by the
plugin to interact with the user (see below).
.IP "plugin_printf" 4
.IX Item "plugin_printf"
A pointer to a printf-style function that may be used to display
informational or error messages (see below).
.IP "settings" 4
.IX Item "settings"
A vector of user-supplied \fBsudo\fR settings in the form of \*(L"name=value\*(R"
strings. The vector is terminated by a \f(CW\*(C`NULL\*(C'\fR pointer. These
settings correspond to flags the user specified when running \fBsudo\fR.
As such, they will only be present when the corresponding flag has
been specified on the command line.
.Sp
When parsing \fIsettings\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.RS 4
.IP "debug_level=number" 4
.IX Item "debug_level=number"
A numeric debug level, from 1\-9, if specified via the \f(CW\*(C`\-D\*(C'\fR flag.
.IP "runas_user=string" 4
.IX Item "runas_user=string"
The user name or uid to to run the command as, if specified via the
\&\f(CW\*(C`\-u\*(C'\fR flag.
.IP "runas_group=string" 4
.IX Item "runas_group=string"
The group name or gid to to run the command as, if specified via
the \f(CW\*(C`\-g\*(C'\fR flag.
.IP "prompt=string" 4
.IX Item "prompt=string"
The prompt to use when requesting a password, if specified via
the \f(CW\*(C`\-p\*(C'\fR flag.
.IP "set_home=bool" 4
.IX Item "set_home=bool"
Set to true if the user specified the \f(CW\*(C`\-H\*(C'\fR flag. If true, set the
\&\f(CW\*(C`HOME\*(C'\fR environment variable to the target user's home directory.
.IP "preserve_environment=bool" 4
.IX Item "preserve_environment=bool"
Set to true if the user specified the \f(CW\*(C`\-E\*(C'\fR flag, indicating that
the user wishes to preserve the environment.
.IP "login_shell=bool" 4
.IX Item "login_shell=bool"
Set to true if the user specified the \f(CW\*(C`\-i\*(C'\fR flag, indicating that
the user wishes to run a login shell.
.IP "implied_shell=bool" 4
.IX Item "implied_shell=bool"
If the user does not specify a program on the command line, \fBsudo\fR
will pass the plugin the path to the user's shell and set
\&\fIimplied_shell\fR to true. This allows \fBsudo\fR with no arguments
to be used similarly to \fIsu\fR\|(1). If the plugin does not to support
this usage, it may return a value of \-2 from the \f(CW\*(C`check_policy\*(C'\fR
function, which will cause \fBsudo\fR to print a usage message and
exit.
.IP "preserve_groups=bool" 4
.IX Item "preserve_groups=bool"
Set to true if the user specified the \f(CW\*(C`\-P\*(C'\fR flag, indicating that
the user wishes to preserve the group vector instead of setting it
based on the runas user.
.IP "ignore_ticket=bool" 4
.IX Item "ignore_ticket=bool"
Set to true if the user specified the \f(CW\*(C`\-k\*(C'\fR flag along with a
command, indicating that the user wishes to ignore any cached
authentication credentials.
.IP "noninteractive=bool" 4
.IX Item "noninteractive=bool"
Set to true if the user specified the \f(CW\*(C`\-n\*(C'\fR flag, indicating that
\&\fBsudo\fR should operate in non-interactive mode. The plugin may
reject a command run in non-interactive mode if user interaction
is required.
.IP "login_class=string" 4
.IX Item "login_class=string"
\&\s-1BSD\s0 login class to use when setting resource limits and nice value,
if specified by the \f(CW\*(C`\-c\*(C'\fR flag.
.IP "selinux_role=string" 4
.IX Item "selinux_role=string"
SELinux role to use when executing the command, if specified by
the \f(CW\*(C`\-r\*(C'\fR flag.
.IP "selinux_type=string" 4
.IX Item "selinux_type=string"
SELinux type to use when executing the command, if specified by
the \f(CW\*(C`\-t\*(C'\fR flag.
.IP "bsdauth_type=string" 4
.IX Item "bsdauth_type=string"
Authentication type, if specified by the \f(CW\*(C`\-a\*(C'\fR flag, to use on
systems where \s-1BSD\s0 authentication is supported.
.IP "progname=string" 4
.IX Item "progname=string"
The command name that sudo was run as, typically \*(L"sudo\*(R" or \*(L"sudoedit\*(R".
.IP "sudoedit=bool" 4
.IX Item "sudoedit=bool"
Set to true when the \f(CW\*(C`\-e\*(C'\fR flag is is specified or if invoked as
\&\fBsudoedit\fR. The plugin shall substitute an editor into \fIargv\fR
in the \fIcheck_policy\fR function or return \f(CW\*(C`\-2\*(C'\fR with a usage error
if the plugin does not support \fIsudoedit\fR. For more information,
see the \fIcheck_policy\fR section.
.RE
.RS 4
.Sp
Additional settings may be added in the future so the plugin should
silently ignore settings that it does not recognize.
.RE
.IP "user_info" 4
.IX Item "user_info"
A vector of information about the user running the command in the form of
\&\*(L"name=value\*(R" strings. The vector is terminated by a \f(CW\*(C`NULL\*(C'\fR pointer.
.Sp
When parsing \fIuser_info\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.RS 4
.IP "user=string" 4
.IX Item "user=string"
The name of the user invoking \fBsudo\fR.
.IP "uid=uid_t" 4
.IX Item "uid=uid_t"
The real user \s-1ID\s0 of the user invoking \fBsudo\fR.
.IP "gid=gid_t" 4
.IX Item "gid=gid_t"
The real group \s-1ID\s0 of the user invoking \fBsudo\fR.
.IP "groups=list" 4
.IX Item "groups=list"
The user's supplementary group list formatted as a string of
comma-separated group IDs.
.IP "cwd=string" 4
.IX Item "cwd=string"
The user's current working directory.
.IP "tty=string" 4
.IX Item "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
\&\f(CW\*(C`tty=\*(C'\fR.
.IP "host=string" 4
.IX Item "host=string"
The local machine's hostname as returned by the \f(CW\*(C`gethostname()\*(C'\fR
system call.
.IP "lines=int" 4
.IX Item "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.
.IP "cols=int" 4
.IX Item "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.
.RE
.RS 4
.RE
.IP "user_env" 4
.IX Item "user_env"
The user's environment in the form of a \f(CW\*(C`NULL\*(C'\fR\-terminated vector of
\&\*(L"name=value\*(R" strings.
.Sp
When parsing \fIuser_env\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.RE
.RS 4
.RE
.IP "close" 4
.IX Item "close"
.Vb 1
\& void (*close)(int exit_status, int error);
.Ve
.Sp
The \f(CW\*(C`close\*(C'\fR function is called when the command being run by \fBsudo\fR
finishes.
.Sp
The function arguments are as follows:
.RS 4
.IP "exit_status" 4
.IX Item "exit_status"
The command's exit status, as returned by the \fIwait\fR\|(2) system call.
The value of \f(CW\*(C`exit_status\*(C'\fR is undefined if \f(CW\*(C`error\*(C'\fR is non-zero.
.IP "error" 4
.IX Item "error"
If the command could not be executed, this is set to the value of
\&\f(CW\*(C`errno\*(C'\fR set by the \fIexecve\fR\|(2) system call. The plugin is responsible
for displaying error information via the conversation or plugin_printf
function. If the command was successfully executed, the value of
\&\f(CW\*(C`error\*(C'\fR is 0.
.RE
.RS 4
.RE
.IP "show_version" 4
.IX Item "show_version"
.Vb 1
\& int (*show_version)(int verbose);
.Ve
.Sp
The \f(CW\*(C`show_version\*(C'\fR function is called by \fBsudo\fR when the user specifies
the \f(CW\*(C`\-V\*(C'\fR option. The plugin may display its version information
to the user via the conversation or plugin_printf function using
\&\f(CW\*(C`SUDO_CONV_INFO_MSG\*(C'\fR. If the user requests detailed version
information, the verbose flag will be set.
.IP "check_policy" 4
.IX Item "check_policy"
.Vb 3
\& int (*check_policy)(int argc, char * const argv[]
\& char *env_add[], char **command_info[],
\& char **argv_out[], char **user_env_out[]);
.Ve
.Sp
The \fIcheck_policy\fR function is called by \fBsudo\fR to determine
whether the user is allowed to run the specified commands.
.Sp
If the \fIsudoedit\fR option was enabled in the \fIsettings\fR array
passed to the \fIopen\fR function, the user has requested \fIsudoedit\fR
mode. \fIsudoedit\fR is a mechanism for editing one or more files
where an editor is run with the user's credentials instead of with
elevated privileges. \fBsudo\fR 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 \fBsudoedit\fR, it should choose the editor to be
used, potentially from a variable in the user's environment, such
as \f(CW\*(C`EDITOR\*(C'\fR, and include it in \fIargv_out\fR (note that environment
variables may include command line flags). The files to be edited
should be copied from \fIargv\fR into \fIargv_out\fR, separated from the
editor and its arguments by a \f(CW"\-\-"\fR element. The \f(CW"\-\-"\fR will
be removed by \fBsudo\fR before the editor is executed. The plugin
should also set \fIsudoedit=true\fR in the \fIcommand_info\fR list.
.Sp
The \fIcheck_policy\fR 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 \fBsudoedit\fR was specified but is unsupported by the plugin.
In the latter case, \fBsudo\fR will print a usage message before it
exits. If an error occurs, the plugin may optionally call the
conversation or plugin_printf function with \f(CW\*(C`SUDO_CONF_ERROR_MSG\*(C'\fR
to present additional error information to the user.
.Sp
The function arguments are as follows:
.RS 4
.IP "argc" 4
.IX Item "argc"
The number of elements in \fIargv\fR, not counting the final \f(CW\*(C`NULL\*(C'\fR
pointer.
.IP "argv" 4
.IX Item "argv"
The argument vector describing the command the user wishes to run,
in the same form as what would be passed to the \fIexecve()\fR system
call. The vector is terminated by a \f(CW\*(C`NULL\*(C'\fR pointer.
.IP "env_add" 4
.IX Item "env_add"
Additional environment variables specified by the user on the command
line in the form of a \f(CW\*(C`NULL\*(C'\fR\-terminated vector of \*(L"name=value\*(R"
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.
.Sp
When parsing \fIenv_add\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.IP "command_info" 4
.IX Item "command_info"
Information about the command being run in the form of \*(L"name=value\*(R"
strings. These values are used by \fBsudo\fR 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 \f(CW\*(C`NULL\*(C'\fR pointer. The following values are recognized by \fBsudo\fR:
.RS 4
.IP "command=string" 4
.IX Item "command=string"
Fully qualified path to the command to be executed.
.IP "runas_uid=uid" 4
.IX Item "runas_uid=uid"
User \s-1ID\s0 to run the command as.
.IP "runas_euid=uid" 4
.IX Item "runas_euid=uid"
Effective user \s-1ID\s0 to run the command as.
If not specified, the value of \fIrunas_uid\fR is used.
.IP "runas_gid=gid" 4
.IX Item "runas_gid=gid"
Group \s-1ID\s0 to run the command as.
.IP "runas_egid=gid" 4
.IX Item "runas_egid=gid"
Effective group \s-1ID\s0 to run the command as.
If not specified, the value of \fIrunas_gid\fR is used.
.IP "runas_groups=list" 4
.IX Item "runas_groups=list"
The supplementary group vector to use for the command in the form
of a comma-separated list of group IDs. If \fIpreserve_groups\fR
is set, this option is ignored.
.IP "login_class=login_class" 4
.IX Item "login_class=login_class"
\&\s-1BSD\s0 login class to use when setting resource limits and nice value
(optional). This option is only set on systems that support login
classes.
.IP "preserve_groups=bool" 4
.IX Item "preserve_groups=bool"
If set, \fBsudo\fR will preserve the user's group vector instead of
initializing the group vector based on \f(CW\*(C`runas_user\*(C'\fR.
.IP "cwd=string" 4
.IX Item "cwd=string"
The current working directory to change to when executing the command.
.IP "noexec=bool" 4
.IX Item "noexec=bool"
If set, prevent the command from executing other programs.
.IP "chroot=string" 4
.IX Item "chroot=string"
The root directory to use when running the command.
.IP "nice=int" 4
.IX Item "nice=int"
Nice value (priority) to use when executing the command. The nice
value, if specified, overrides the priority associated with the
\&\fIlogin_class\fR on \s-1BSD\s0 systems.
.IP "umask=octal" 4
.IX Item "umask=octal"
The file creation mask to use when executing the command.
.IP "selinux_role=string" 4
.IX Item "selinux_role=string"
SELinux role to use when executing the command.
.IP "selinux_type=string" 4
.IX Item "selinux_type=string"
SELinux type to use when executing the command.
.IP "timeout=int" 4
.IX Item "timeout=int"
Command timeout. If non-zero then when the timeout expires the
command will be killed.
.IP "sudoedit=bool" 4
.IX Item "sudoedit=bool"
Set to true when in \fIsudoedit\fR mode. The plugin may enable
\&\fIsudoedit\fR mode even if \fBsudo\fR was not invoked as \fBsudoedit\fR.
This allows the plugin to perform command substitution and transparently
enable \fIsudoedit\fR when the user attempts to run an editor.
.RE
.RS 4
.Sp
Unsupported values will be ignored.
.RE
.IP "argv_out" 4
.IX Item "argv_out"
The \f(CW\*(C`NULL\*(C'\fR\-terminated argument vector to pass to the \fIexecve()\fR
system call when executing the command. The plugin is responsible
for allocating and populating the vector.
.IP "user_env_out" 4
.IX Item "user_env_out"
The \f(CW\*(C`NULL\*(C'\fR\-terminated environment vector to use when executing the
command. The plugin is responsible for allocating and populating
the vector.
.RE
.RS 4
.RE
.IP "list" 4
.IX Item "list"
.Vb 2
\& int (*list)(int verbose, const char *list_user,
\& int argc, char * const argv[]);
.Ve
.Sp
List available privileges for the invoking user. Returns 1 on
success, 0 on failure and \-1 on error. On error, the plugin may
optionally call the conversation or plugin_printf function with
\&\f(CW\*(C`SUDO_CONF_ERROR_MSG\*(C'\fR to present additional error information to
the user.
.Sp
Privileges should be output via the conversation or plugin_printf
function using \f(CW\*(C`SUDO_CONV_INFO_MSG\*(C'\fR.
.RS 4
.IP "verbose" 4
.IX Item "verbose"
Flag indicating whether to list in verbose mode or not.
.IP "list_user" 4
.IX Item "list_user"
The name of a different user to list privileges for if the policy
allows it. If \f(CW\*(C`NULL\*(C'\fR, the plugin should list the privileges of
the invoking user.
.IP "argc" 4
.IX Item "argc"
The number of elements in \fIargv\fR, not counting the final \f(CW\*(C`NULL\*(C'\fR
pointer.
.IP "argv" 4
.IX Item "argv"
If non\-\f(CW\*(C`NULL\*(C'\fR, 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 \fIexecve()\fR 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.
.RE
.RS 4
.RE
.IP "validate" 4
.IX Item "validate"
.Vb 1
\& int (*validate)(void);
.Ve
.Sp
The \f(CW\*(C`validate\*(C'\fR function is called when \fBsudo\fR is run with the
\&\f(CW\*(C`\-v\*(C'\fR flag. For policy plugins such as \fIsudoers\fR that cache
authentication credentials, this function will validate and cache
the credentials.
.Sp
The \f(CW\*(C`validate\*(C'\fR function should be \f(CW\*(C`NULL\*(C'\fR if the plugin does not
support credential caching.
.Sp
Returns 1 on success, 0 on failure and \-1 on error.
On error, the plugin may optionally call the conversation or plugin_printf
function with \f(CW\*(C`SUDO_CONF_ERROR_MSG\*(C'\fR to present additional
error information to the user.
.IP "invalidate" 4
.IX Item "invalidate"
.Vb 1
\& void (*invalidate)(int remove);
.Ve
.Sp
The \f(CW\*(C`invalidate\*(C'\fR function is called when \fBsudo\fR is called with
the \f(CW\*(C`\-k\*(C'\fR or \f(CW\*(C`\-K\*(C'\fR flag. For policy plugins such as \fIsudoers\fR that
cache authentication credentials, this function will invalidate the
credentials. If the \fIremove\fR flag is set, the plugin may remove
the credentials instead of simply invalidating them.
.Sp
The \f(CW\*(C`invalidate\*(C'\fR function should be \f(CW\*(C`NULL\*(C'\fR if the plugin does not
support credential caching.
.PP
\fIConversation \s-1API\s0\fR
.IX Subsection "Conversation API"
.PP
If the plugin needs to interact with the user, it may do so via the
conversation function. A plugin should not attempt to read directly
from the standard input or the user's tty (neither of which are
guaranteed to exist). The caller must include a trailing newline
in \f(CW\*(C`msg\*(C'\fR if one is to be printed.
.PP
A printf-style function is also available that can be used to display
informational or error messages to the user, which is usually more
convenient for simple messages where no use input is required.
.PP
.Vb 9
\& struct sudo_conv_message {
\& #define SUDO_CONV_PROMPT_ECHO_OFF 1
\& #define SUDO_CONV_PROMPT_ECHO_ON 2
\& #define SUDO_CONV_ERROR_MSG 3
\& #define SUDO_CONV_INFO_MSG 4
\& int msg_type;
\& int timeout;
\& const char *msg;
\& };
\&
\& struct sudo_conv_reply {
\& char *reply;
\& };
\&
\& typedef int (*sudo_conv_t)(int num_msgs,
\& const struct sudo_conv_message msgs[],
\& struct sudo_conv_reply replies[]);
\&
\& typedef int (*sudo_printf_t)(int msg_type, const char *fmt, ...);
.Ve
.PP
Pointers to the conversation and printf-style functions are passed
in to the plugin's \f(CW\*(C`open\*(C'\fR function when the plugin is initialized.
.PP
To use the conversation function, the plugin must pass an array of
\&\f(CW\*(C`sudo_conv_message\*(C'\fR and \f(CW\*(C`sudo_conv_reply\*(C'\fR structures. There must
be a \f(CW\*(C`struct sudo_conv_message\*(C'\fR and \f(CW\*(C`struct sudo_conv_reply\*(C'\fR for
each message in the conversation. The plugin is responsible for
freeing the reply buffer filled in to the \f(CW\*(C`struct sudo_conv_reply\*(C'\fR,
if any.
.PP
The printf-style function uses the same underlying mechanism as the
conversation function but only supports \f(CW\*(C`SUDO_CONV_INFO_MSG\*(C'\fR and
\&\f(CW\*(C`SUDO_CONV_ERROR_MSG\*(C'\fR for the \fImsg_type\fR parameter. It can be
more convenient than using the conversation function if no user
reply is needed and supports standard \fIprintf()\fR escape sequences.
.PP
See the sample plugin for an example of the conversation function usage.
.SS "I/O Plugin \s-1API\s0"
.IX Subsection "I/O Plugin API"
.Vb 10
\& 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 user_env[]);
\& 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);
\& };
.Ve
.PP
When an I/O plugin is loaded, \fBsudo\fR 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, \fBsudo\fR 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 log_stdin, log_stdout and log_stderr
functions are only called if the standard input, standard output
or standard error respectively correspond to something other than
a tty.
.PP
Any of the logging functions may be set to the \s-1NULL\s0
pointer if no logging is to be performed. If the open function
returns \f(CW0\fR, no I/O will be sent to the plugin.
.PP
The io_plugin struct has the following fields:
.IP "type" 4
.IX Item "type"
The \f(CW\*(C`type\*(C'\fR field should always be set to \s-1SUDO_IO_PLUGIN\s0
.IP "version" 4
.IX Item "version"
The \f(CW\*(C`version\*(C'\fR field should be set to \s-1SUDO_API_VERSION\s0.
.Sp
This allows \fBsudo\fR to determine the \s-1API\s0 version the plugin was
built against.
.IP "open" 4
.IX Item "open"
.Vb 3
\& 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[]);
.Ve
.Sp
The \fIopen\fR function is run before the \fIlog_input\fR, \fIlog_output\fR
or \fIshow_version\fR functions are called. It is only called if the
version is being requested or the \fIcheck_policy\fR 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, \fBsudo\fR will print a usage message before it exits.
If an error occurs, the plugin may optionally call the conversation
or plugin_printf function with \f(CW\*(C`SUDO_CONF_ERROR_MSG\*(C'\fR to present
additional error information to the user.
.Sp
The function arguments are as follows:
.RS 4
.IP "version" 4
.IX Item "version"
The version passed in by \fBsudo\fR allows the plugin to determine the
major and minor version number of the plugin \s-1API\s0 supported by
\&\fBsudo\fR.
.IP "conversation" 4
.IX Item "conversation"
A pointer to the conversation function that may be used by the
\&\fIshow_version\fR function to display version information (see
show_version below). The conversation function may also be used
to display additional error message to the user.
.IP "plugin_printf" 4
.IX Item "plugin_printf"
A pointer to a printf-style function that may be used by the
\&\fIshow_version\fR function to display version information (see
show_version below). The plugin_printf function may also be used
to display additional error message to the user.
.IP "settings" 4
.IX Item "settings"
A vector of user-supplied \fBsudo\fR settings in the form of \*(L"name=value\*(R"
strings. The vector is terminated by a \f(CW\*(C`NULL\*(C'\fR pointer. These
settings correspond to flags the user specified when running \fBsudo\fR.
As such, they will only be present when the corresponding flag has
been specified on the command line.
.Sp
When parsing \fIsettings\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.Sp
See the \*(L"Policy Plugin \s-1API\s0\*(R" section for a list of all possible settings.
.IP "user_info" 4
.IX Item "user_info"
A vector of information about the user running the command in the form of
\&\*(L"name=value\*(R" strings. The vector is terminated by a \f(CW\*(C`NULL\*(C'\fR pointer.
.Sp
When parsing \fIuser_info\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.Sp
See the \*(L"Policy Plugin \s-1API\s0\*(R" section for a list of all possible strings.
.IP "user_env" 4
.IX Item "user_env"
The user's environment in the form of a \f(CW\*(C`NULL\*(C'\fR\-terminated vector of
\&\*(L"name=value\*(R" strings.
.Sp
When parsing \fIuser_env\fR, the plugin should split on the \fBfirst\fR
equal sign ('=') since the \fIname\fR field will never include one
itself but the \fIvalue\fR might.
.RE
.RS 4
.RE
.IP "close" 4
.IX Item "close"
.Vb 1
\& void (*close)(int exit_status, int error);
.Ve
.Sp
The \f(CW\*(C`close\*(C'\fR function is called when the command being run by \fBsudo\fR
finishes.
.Sp
The function arguments are as follows:
.RS 4
.IP "exit_status" 4
.IX Item "exit_status"
The command's exit status, as returned by the \fIwait\fR\|(2) system call.
The value of \f(CW\*(C`exit_status\*(C'\fR is undefined if \f(CW\*(C`error\*(C'\fR is non-zero.
.IP "error" 4
.IX Item "error"
If the command could not be executed, this is set to the value of
\&\f(CW\*(C`errno\*(C'\fR set by the \fIexecve\fR\|(2) system call. If the command was
successfully executed, the value of \f(CW\*(C`error\*(C'\fR is 0.
.RE
.RS 4
.RE
.IP "show_version" 4
.IX Item "show_version"
.Vb 1
\& int (*show_version)(int verbose);
.Ve
.Sp
The \f(CW\*(C`show_version\*(C'\fR function is called by \fBsudo\fR when the user specifies
the \f(CW\*(C`\-V\*(C'\fR option. The plugin may display its version information
to the user via the conversation or plugin_printf function using
\&\f(CW\*(C`SUDO_CONV_INFO_MSG\*(C'\fR. If the user requests detailed version
information, the verbose flag will be set.
.IP "log_ttyin" 4
.IX Item "log_ttyin"
.Vb 1
\& int (*log_ttyin)(const char *buf, unsigned int len);
.Ve
.Sp
The \fIlog_ttyin\fR 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 \f(CW1\fR if the data
should be passed to the command, \f(CW0\fR if the data is rejected
(which will terminate the command) or \f(CW\*(C`\-1\*(C'\fR if an error occurred.
.Sp
The function arguments are as follows:
.RS 4
.IP "buf" 4
.IX Item "buf"
The buffer containing user input.
.IP "len" 4
.IX Item "len"
The length of \fIbuf\fR in bytes.
.RE
.RS 4
.RE
.IP "log_ttyout" 4
.IX Item "log_ttyout"
.Vb 1
\& int (*log_ttyout)(const char *buf, unsigned int len);
.Ve
.Sp
The \fIlog_ttyout\fR 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 \f(CW1\fR if the data
should be passed to the user, \f(CW0\fR if the data is rejected
(which will terminate the command) or \f(CW\*(C`\-1\*(C'\fR if an error occurred.
.Sp
The function arguments are as follows:
.RS 4
.IP "buf" 4
.IX Item "buf"
The buffer containing command output.
.IP "len" 4
.IX Item "len"
The length of \fIbuf\fR in bytes.
.RE
.RS 4
.RE
.IP "log_stdin" 4
.IX Item "log_stdin"
.Vb 1
\& int (*log_stdin)(const char *buf, unsigned int len);
.Ve
.Sp
The \fIlog_stdin\fR 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 \f(CW1\fR
if the data should be passed to the command, \f(CW0\fR if the data is
rejected (which will terminate the command) or \f(CW\*(C`\-1\*(C'\fR if an error
occurred.
.Sp
The function arguments are as follows:
.RS 4
.IP "buf" 4
.IX Item "buf"
The buffer containing user input.
.IP "len" 4
.IX Item "len"
The length of \fIbuf\fR in bytes.
.RE
.RS 4
.RE
.IP "log_stdout" 4
.IX Item "log_stdout"
.Vb 1
\& int (*log_stdout)(const char *buf, unsigned int len);
.Ve
.Sp
The \fIlog_stdout\fR 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 \f(CW1\fR
if the data should be passed to the user, \f(CW0\fR if the data is
rejected (which will terminate the command) or \f(CW\*(C`\-1\*(C'\fR if an error
occurred.
.Sp
The function arguments are as follows:
.RS 4
.IP "buf" 4
.IX Item "buf"
The buffer containing command output.
.IP "len" 4
.IX Item "len"
The length of \fIbuf\fR in bytes.
.RE
.RS 4
.RE
.IP "log_stderr" 4
.IX Item "log_stderr"
.Vb 1
\& int (*log_stderr)(const char *buf, unsigned int len);
.Ve
.Sp
The \fIlog_stderr\fR 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 \f(CW1\fR
if the data should be passed to the user, \f(CW0\fR if the data is
rejected (which will terminate the command) or \f(CW\*(C`\-1\*(C'\fR if an error
occurred.
.Sp
The function arguments are as follows:
.RS 4
.IP "buf" 4
.IX Item "buf"
The buffer containing command output.
.IP "len" 4
.IX Item "len"
The length of \fIbuf\fR in bytes.
.RE
.RS 4
.RE
.SS "Unsupported command line options"
.IX Subsection "Unsupported command line options"
The \f(CW\*(C`\-L\*(C'\fR command line option has been deprecated as its output is
covered by the \fIsudoers\fR manual page.
.SS "Sudo implementation details"
.IX Subsection "Sudo implementation details"
Version macros:
.PP
.Vb 8
\& #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_VERSION_SET_MINOR(vp, n) do { \e
\& *(vp) = (*(vp) & 0xffff0000) | (n); \e
\& } while(0)
\&
\& #define SUDO_API_VERSION_MAJOR 1
\& #define SUDO_API_VERSION_MINOR 0
\& #define SUDO_API_VERSION ((SUDO_API_VERSION_MAJOR << 16) | SUDO_API_VERSION_MINOR)
.Ve
.PP
Sudo will cast the plugin symbol to the following when determining
the plugin type.
.PP
.Vb 4
\& union sudo_plugin {
\& struct policy_plugin policy;
\& struct io_plugin io;
\& };
.Ve
.SH "POD ERRORS"
.IX Header "POD ERRORS"
Hey! \fBThe above document had some coding errors, which are explained below:\fR
.IP "Around line 597:" 4
.IX Item "Around line 597:"
You forgot a '=back' before '=head3'
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