sudo_plugin
(1m)
名前
sudo_plugin - Sudo Plugin API
形式
Please see following description for synopsis
説明
Standards, Environments, and Macros SUDO_PLUGIN(5)
NAME
sudo_plugin - Sudo Plugin API
DESCRIPTION
Starting with version 1.8, sudo supports a plugin API for
policy and session logging. By default, the sudoers policy
plugin and an associated I/O logging plugin are used. Via
the plugin API, 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 via the /etc/sudo.conf
file.
The API is versioned with a major and minor number. The
minor version number is incremented when additions are made.
The major number is incremented when incompatible changes
are made. A plugin should be check the version passed to it
and make sure that the major version matches.
The plugin API is defined by the sudo_plugin.h header file.
The sudo.conf file
The /etc/sudo.conf file contains plugin configuration
directives. The primary keyword is the Plugin directive,
which causes a plugin to be loaded.
A Plugin line consists of the Plugin keyword, followed by
the symbol_name and the path to the shared object containing
the plugin. The symbol_name is the name of the struct
policy_plugin or struct io_plugin in the plugin shared
object. The path may be fully qualified or relative. If
not fully qualified it is relative to the /usr/libexec
directory. Any additional parameters after the path are
passed as options to the plugin's open() function. Lines
that don't begin with Plugin, Path, Debug or Set are
silently ignored.
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.
#
# Default /etc/sudo.conf file
#
# Format:
# Plugin plugin_name plugin_path plugin_options ...
# Path askpass /path/to/askpass
# Path noexec /path/to/sudo_noexec.so
# Debug sudo /var/log/sudo_debug all@warn
# Set disable_coredump true
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#
# The plugin_path is relative to /usr/libexec unless
# fully qualified.
# The plugin_name corresponds to a global symbol in the plugin
# that contains the plugin interface structure.
# The plugin_options are optional.
#
Plugin sudoers_policy sudoers.so
Plugin sudoers_io sudoers.so
Policy plugin API
A policy plugin must declare and populate a policy_plugin
struct in the global scope. This structure contains
pointers to the functions that implement the sudo policy
checks. The name of the symbol should be specified in
/etc/sudo.conf along with a path to the plugin so that sudo
can load it.
struct policy_plugin {
#define SUDO_POLICY_PLUGIN 1
unsigned int type; /* always SUDO_POLICY_PLUGIN */
unsigned int version; /* always SUDO_API_VERSION */
int (*open)(unsigned int version, sudo_conv_t conversation,
sudo_printf_t plugin_printf, char * const settings[],
char * const user_info[], char * const user_env[],
char * const plugin_options[]);
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));
};
The policy_plugin struct has the following fields:
type The type field should always be set to
SUDO_POLICY_PLUGIN.
version
The version field should be set to SUDO_API_VERSION.
This allows sudo to determine the API version the
plugin was built against.
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open
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[]);
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, sudo will print a usage message
before it exits. If an error occurs, the plugin may
optionally call the conversation() or plugin_printf()
function with SUDO_CONF_ERROR_MSG to present
additional error information to the user.
The function arguments are as follows:
version
The version passed in by sudo allows the plugin
to determine the major and minor version number
of the plugin API supported by sudo.
conversation
A pointer to the conversation() function that
can be used by the plugin to interact with the
user (see below). Returns 0 on success and -1
on failure.
plugin_printf
A pointer to a printf()-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.
settings
A vector of user-supplied sudo settings in the
form of ``name=value'' strings. The vector is
terminated by a NULL pointer. These settings
correspond to flags the user specified when
running sudo. As such, they will only be
present when the corresponding flag has been
specified on the command line.
When parsing settings, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
debug_flags=string
A comma-separated list of debug flags that
correspond to sudo's Debug entry in
/etc/sudo.conf, if there is one. The
flags are passed to the plugin as they
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appear in /etc/sudo.conf. The syntax used
by sudo and the sudoers plugin is
subsystem@priority but the plugin is free
to use a different format so long as it
does not include a comma (`,').
For reference, the priorities supported by
the sudo front end and sudoers are: crit,
err, warn, notice, diag, info, trace and
debug.
The following subsystems are defined:
main, memory, args, exec, pty, utmp, conv,
pcomm, util, list, netif, audit, edit,
selinux, ldap, match, parser, alias,
defaults, auth, env, logging, nss, rbtree,
perms, plugin. The subsystem all includes
every subsystem.
There is not currently a way to specify a
set of debug flags specific to the
plugin--the flags are shared by sudo and
the plugin.
debug_level=number
This setting has been deprecated in favor
of debug_flags.
runas_user=string
The user name or uid to to run the command
as, if specified via the -u flag.
runas_group=string
The group name or gid to to run the
command as, if specified via the -g flag.
prompt=string
The prompt to use when requesting a
password, if specified via the -p flag.
set_home=bool
Set to true if the user specified the -H
flag. If true, set the HOME environment
variable to the target user's home
directory.
preserve_environment=bool
Set to true if the user specified the -E
flag, indicating that the user wishes to
preserve the environment.
run_shell=bool
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Set to true if the user specified the -s
flag, indicating that the user wishes to
run a shell.
login_shell=bool
Set to true if the user specified the -i
flag, indicating that the user wishes to
run a login shell.
implied_shell=bool
If the user does not specify a program on
the command line, sudo will pass the
plugin the path to the user's shell and
set implied_shell to true. This allows
sudo with no arguments to be used
similarly to su(1). If the plugin does
not to support this usage, it may return a
value of -2 from the check_policy()
function, which will cause sudo to print a
usage message and exit.
preserve_groups=bool
Set to true if the user specified the -P
flag, indicating that the user wishes to
preserve the group vector instead of
setting it based on the runas user.
ignore_ticket=bool
Set to true if the user specified the -k
flag along with a command, indicating that
the user wishes to ignore any cached
authentication credentials.
noninteractive=bool
Set to true if the user specified the -n
flag, indicating that sudo should operate
in non-interactive mode. The plugin may
reject a command run in non-interactive
mode if user interaction is required.
login_class=string
BSD login class to use when setting
resource limits and nice value, if
specified by the -c flag.
selinux_role=string
SELinux role to use when executing the
command, if specified by the -r flag.
selinux_type=string
SELinux type to use when executing the
command, if specified by the -t flag.
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bsdauth_type=string
Authentication type, if specified by the
-a flag, to use on systems where BSD
authentication is supported.
network_addrs=list
A space-separated list of IP network
addresses and netmasks in the form
``addr/netmask'', e.g.
``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 (`:'), it is an IPv6
address, else it is IPv4.
progname=string
The command name that sudo was run as,
typically ``sudo'' or ``sudoedit''.
sudoedit=bool
Set to true when the -e flag is is
specified or if invoked as sudoedit. The
plugin shall substitute an editor into
argv in the check_policy() function or
return -2 with a usage error if the plugin
does not support sudoedit. For more
information, see the check_policy section.
closefrom=number
If specified, the user has requested via
the -C flag that sudo close all files
descriptors with a value of number or
higher. The plugin may optionally pass
this, or another value, back in the
command_info list.
Additional settings may be added in the future
so the plugin should silently ignore settings
that it does not recognize.
user_info
A vector of information about the user running
the command in the form of ``name=value''
strings. The vector is terminated by a NULL
pointer.
When parsing user_info, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
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pid=int
The process ID of the running sudo
process. Only available starting with API
version 1.2
ppid=int
The parent process ID of the running sudo
process. Only available starting with API
version 1.2
sid=int
The session ID of the running sudo process
or 0 if sudo is not part of a POSIX job
control session. Only available starting
with API version 1.2
pgid=int
The ID of the process group that the
running sudo process belongs to. Only
available starting with API version 1.2
tcpgid=int
The ID of the forground process group
associated with the terminal device
associcated with the sudo process or -1 if
there is no terminal present. Only
available starting with API version 1.2
user=string
The name of the user invoking sudo.
euid=uid_t
The effective user ID of the user invoking
sudo.
uid=uid_t
The real user ID of the user invoking
sudo.
egid=gid_t
The effective group ID of the user
invoking sudo.
gid=gid_t
The real group ID of the user invoking
sudo.
groups=list
The user's supplementary group list
formatted as a string of comma-separated
group IDs.
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cwd=string
The user's current working directory.
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 ``tty=''.
host=string
The local machine's hostname as returned
by the gethostname(2) system call.
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.
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.
user_env
The user's environment in the form of a NULL-
terminated vector of ``name=value'' strings.
When parsing user_env, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
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 NULL-terminated array of strings.
If no arguments were specified, plugin_options
will be the NULL pointer.
NOTE: the plugin_options parameter is only
available starting with API version 1.2. A
plugin must check the API version specified by
the sudo front end before using plugin_options.
Failure to do so may result in a crash.
close
void (*close)(int exit_status, int error);
The close() function is called when the command being
run by sudo finishes.
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The function arguments are as follows:
exit_status
The command's exit status, as returned by the
wait(2) system call. The value of exit_status
is undefined if error is non-zero.
error
If the command could not be executed, this is
set to the value of errno set by the execve(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 error is 0.
show_version
int (*show_version)(int verbose);
The show_version() function is called by sudo when the
user specifies the -V option. The plugin may display
its version information to the user via the
conversation() or plugin_printf() function using
SUDO_CONV_INFO_MSG. If the user requests detailed
version information, the verbose flag will be set.
check_policy
int (*check_policy)(int argc, char * const argv[]
char *env_add[], char **command_info[],
char **argv_out[], char **user_env_out[]);
The check_policy() function is called by sudo to
determine whether the user is allowed to run the
specified commands.
If the sudoedit option was enabled in the settings
array passed to the open() function, the user has
requested sudoedit mode. 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. 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 sudoedit, it should choose the editor to be
used, potentially from a variable in the user's
environment, such as EDITOR, and include it in
argv_out (note that environment variables may include
command line flags). The files to be edited should be
copied from argv into argv_out, separated from the
editor and its arguments by a ``--'' element. The
``--'' will be removed by sudo before the editor is
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executed. The plugin should also set sudoedit=true in
the command_info list.
The 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 sudoedit was specified
but is unsupported by the plugin. In the latter case,
sudo will print a usage message before it exits. If
an error occurs, the plugin may optionally call the
conversation() or plugin_printf() function with
SUDO_CONF_ERROR_MSG to present additional error
information to the user.
The function arguments are as follows:
argc The number of elements in argv, not counting the
final NULL pointer.
argv The argument vector describing the command the
user wishes to run, in the same form as what
would be passed to the execve(2) system call.
The vector is terminated by a NULL pointer.
env_add
Additional environment variables specified by
the user on the command line in the form of a
NULL-terminated vector of ``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.
When parsing env_add, the plugin should split on
the first equal sign (`=') since the name field
will never include one itself but the value
might.
command_info
Information about the command being run in the
form of ``name=value'' strings. These values
are used by 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 NULL
pointer. The following values are recognized by
sudo:
command=string
Fully qualified path to the command to be
executed.
runas_uid=uid
User ID to run the command as.
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runas_euid=uid
Effective user ID to run the command as.
If not specified, the value of runas_uid
is used.
runas_gid=gid
Group ID to run the command as.
runas_egid=gid
Effective group ID to run the command as.
If not specified, the value of runas_gid
is used.
runas_groups=list
The supplementary group vector to use for
the command in the form of a comma-
separated list of group IDs. If
preserve_groups is set, this option is
ignored.
login_class=string
BSD login class to use when setting
resource limits and nice value (optional).
This option is only set on systems that
support login classes.
preserve_groups=bool
If set, sudo will preserve the user's
group vector instead of initializing the
group vector based on runas_user.
cwd=string
The current working directory to change to
when executing the command.
noexec=bool
If set, prevent the command from executing
other programs.
chroot=string
The root directory to use when running the
command.
nice=int
Nice value (priority) to use when
executing the command. The nice value, if
specified, overrides the priority
associated with the login_class on BSD
systems.
umask=octal
The file creation mask to use when
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executing the command.
selinux_role=string
SELinux role to use when executing the
command.
selinux_type=string
SELinux type to use when executing the
command.
timeout=int
Command timeout. If non-zero then when
the timeout expires the command will be
killed.
sudoedit=bool
Set to true when in sudoedit mode. The
plugin may enable sudoedit mode even if
sudo was not invoked as sudoedit. This
allows the plugin to perform command
substitution and transparently enable
sudoedit when the user attempts to run an
editor.
closefrom=number
If specified, sudo will close all files
descriptors with a value of number or
higher.
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.
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.
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.
iolog_stdout=bool
Set to true if the I/O logging plugins, if
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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.
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.
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.
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.
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, sudo will
only run the command in a pty when an I/O
log plugin is loaded.
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.
utmp_user=string
User name to use when constructing a new
utmp (or utmpx) entry when 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, sudo will base
the new entry on the invoking user's
existing entry.
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Unsupported values will be ignored.
argv_out
The NULL-terminated argument vector to pass to
the execve(2) system call when executing the
command. The plugin is responsible for
allocating and populating the vector.
user_env_out
The NULL-terminated environment vector to use
when executing the command. The plugin is
responsible for allocating and populating the
vector.
list
int (*list)(int verbose, const char *list_user,
int argc, char * const argv[]);
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
SUDO_CONF_ERROR_MSG to present additional error
information to the user.
Privileges should be output via the conversation() or
plugin_printf() function using SUDO_CONV_INFO_MSG,
verbose
Flag indicating whether to list in verbose mode
or not.
list_user
The name of a different user to list privileges
for if the policy allows it. If NULL, the
plugin should list the privileges of the
invoking user.
argc The number of elements in argv, not counting the
final NULL pointer.
argv If non-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 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.
validate
int (*validate)(void);
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The validate() function is called when sudo is run
with the -v flag. For policy plugins such as sudoers
that cache authentication credentials, this function
will validate and cache the credentials.
The validate() function should be NULL if the plugin
does not support credential caching.
Returns 1 on success, 0 on failure and -1 on error.
On error, the plugin may optionally call the
conversation() or plugin_printf() function with
SUDO_CONF_ERROR_MSG to present additional error
information to the user.
invalidate
void (*invalidate)(int remove);
The invalidate() function is called when sudo is
called with the -k or -K flag. For policy plugins
such as sudoers that cache authentication credentials,
this function will invalidate the credentials. If the
remove flag is set, the plugin may remove the
credentials instead of simply invalidating them.
The invalidate() function should be NULL if the plugin
does not support credential caching.
init_session
int (*init_session)(struct passwd *pwd, char **user_envp[);
The init_session() function is called before sudo sets
up the execution environment for the command. It is
run in the parent sudo process and before any uid or
gid changes. This can be used to perform session
setup that is not supported by command_info, such as
opening the PAM session. The close() function can be
used to tear down the session that was opened by
init_session.
The 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 NULL.
The user_env argument points to the environment the
command will run in, in the form of a NULL-terminated
vector of ``name=value'' strings. This is the same
string passed back to the front end via the Policy
Plugin's user_env_out parameter. If the
init_session() function needs to modify the user
environment, it should update the pointer stored in
user_env. The expected use case is to merge the
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contents of the PAM environment (if any) with the
contents of user_env. NOTE: the user_env parameter is
only available starting with API version 1.2. A
plugin must check the API version specified by the
sudo front end before using user_env. Failure to do
so may result in a crash.
Returns 1 on success, 0 on failure and -1 on error.
On error, the plugin may optionally call the
conversation() or plugin_printf() function with
SUDO_CONF_ERROR_MSG to present additional error
information to the user.
register_hooks
void (*register_hooks)(int version,
int (*register_hook)(struct sudo_hook *hook));
The register_hooks() function is called by the sudo
front end to register any hooks the plugin needs. If
the plugin does not support hooks, register_hooks
should be set to the NULL pointer.
The version argument describes the version of the
hooks API supported by the sudo front end.
The 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 struct hook
does not match the front end's major hook API version.
See the Hook function API section below for more
information about hooks.
NOTE: the register_hooks() function is only available
starting with API version 1.2. If the sudo front end
doesn't support API version 1.2 or higher,
register_hooks will not be called.
deregister_hooks
void (*deregister_hooks)(int version,
int (*deregister_hook)(struct sudo_hook *hook));
The 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,
deregister_hooks should be set to the NULL pointer.
The version argument describes the version of the
hooks API supported by the sudo front end.
The deregister_hook() function should be used to
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deregister any hooks that were put in place by the
register_hook() function. If the plugin tries to
deregister a hook that the front end does not support,
deregister_hook will return an error.
See the Hook function API section below for more
information about hooks.
NOTE: the deregister_hooks() function is only
available starting with API version 1.2. If the sudo
front end doesn't support API version 1.2 or higher,
deregister_hooks will not be called.
Policy Plugin Version Macros
/* Plugin API version major/minor. */
#define SUDO_API_VERSION_MAJOR 1
#define SUDO_API_VERSION_MINOR 2
#define SUDO_API_MKVERSION(x, y) ((x << 16) | y)
#define SUDO_API_VERSION SUDO_API_MKVERSION(SUDO_API_VERSION_MAJOR,\
SUDO_API_VERSION_MINOR)
/* Getters and setters for API version */
#define SUDO_API_VERSION_GET_MAJOR(v) ((v) >> 16)
#define SUDO_API_VERSION_GET_MINOR(v) ((v) & 0xffff)
#define SUDO_API_VERSION_SET_MAJOR(vp, n) do { \
*(vp) = (*(vp) & 0x0000ffff) | ((n) << 16); \
} while(0)
#define SUDO_VERSION_SET_MINOR(vp, n) do { \
*(vp) = (*(vp) & 0xffff0000) | (n); \
} while(0)
I/O plugin API
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[], 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));
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};
When an I/O plugin is loaded, 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, sudo will open a pipe to capture the I/O for
logging before passing it on.
The log_ttyin function receives the raw user input from the
terminal device (note that this will include input even when
echo is disabled, such as when a password is read). The
log_ttyout function receives output from the pseudo-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.
Any of the logging functions may be set to the NULL pointer
if no logging is to be performed. If the open function
returns 0, no I/O will be sent to the plugin.
The io_plugin struct has the following fields:
type The type field should always be set to SUDO_IO_PLUGIN.
version
The version field should be set to SUDO_API_VERSION.
This allows sudo to determine the API version the
plugin was built against.
open
int (*open)(unsigned int version, sudo_conv_t conversation
sudo_printf_t plugin_printf, char * const settings[],
char * const user_info[], int argc, char * const argv[],
char * const user_env[], char * const plugin_options[]);
The open() function is run before the log_input(),
log_output() or show_version() functions are called.
It is only called if the version is being requested or
the 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, sudo will print a usage message
before it exits. If an error occurs, the plugin may
optionally call the conversation() or plugin_printf()
function with SUDO_CONF_ERROR_MSG to present
additional error information to the user.
The function arguments are as follows:
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version
The version passed in by sudo allows the plugin
to determine the major and minor version number
of the plugin API supported by sudo.
conversation
A pointer to the conversation() function that
may be used by the show_version() function to
display version information (see show_version()
below). The conversation() function may also be
used to display additional error message to the
user. The conversation() function returns 0 on
success and -1 on failure.
plugin_printf
A pointer to a printf()-style function that may
be used by the show_version() 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. The plugin_printf() function returns
number of characters printed on success and -1
on failure.
settings
A vector of user-supplied sudo settings in the
form of ``name=value'' strings. The vector is
terminated by a NULL pointer. These settings
correspond to flags the user specified when
running sudo. As such, they will only be
present when the corresponding flag has been
specified on the command line.
When parsing settings, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
See the Policy plugin API section for a list of
all possible settings.
user_info
A vector of information about the user running
the command in the form of ``name=value''
strings. The vector is terminated by a NULL
pointer.
When parsing user_info, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
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See the Policy plugin API section for a list of
all possible strings.
argc The number of elements in argv, not counting the
final NULL pointer.
argv If non-NULL, an argument vector describing a
command the user wishes to run in the same form
as what would be passed to the execve(2) system
call.
user_env
The user's environment in the form of a NULL-
terminated vector of ``name=value'' strings.
When parsing user_env, the plugin should split
on the first equal sign (`=') since the name
field will never include one itself but the
value might.
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 NULL-terminated array of strings.
If no arguments were specified, plugin_options
will be the NULL pointer.
NOTE: the plugin_options parameter is only
available starting with API version 1.2. A
plugin must check the API version specified by
the sudo front end before using plugin_options.
Failure to do so may result in a crash.
close
void (*close)(int exit_status, int error);
The close() function is called when the command being
run by sudo finishes.
The function arguments are as follows:
exit_status
The command's exit status, as returned by the
wait(2) system call. The value of exit_status
is undefined if error is non-zero.
error
If the command could not be executed, this is
set to the value of errno set by the execve(2)
system call. If the command was successfully
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executed, the value of error is 0.
show_version
int (*show_version)(int verbose);
The show_version() function is called by sudo when the
user specifies the -V option. The plugin may display
its version information to the user via the
conversation() or plugin_printf() function using
SUDO_CONV_INFO_MSG. If the user requests detailed
version information, the verbose flag will be set.
log_ttyin
int (*log_ttyin)(const char *buf, unsigned int len);
The 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 command) or -1 if
an error occurred.
The function arguments are as follows:
buf The buffer containing user input.
len The length of buf in bytes.
log_ttyout
int (*log_ttyout)(const char *buf, unsigned int len);
The 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 command) or -1 if
an error occurred.
The function arguments are as follows:
buf The buffer containing command output.
len The length of buf in bytes.
log_stdin
int (*log_stdin)(const char *buf, unsigned int len);
The log_stdin() function is only used if the standard
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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
command) or -1 if an error occurred.
The function arguments are as follows:
buf The buffer containing user input.
len The length of buf in bytes.
log_stdout
int (*log_stdout)(const char *buf, unsigned int len);
The 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
command) or -1 if an error occurred.
The function arguments are as follows:
buf The buffer containing command output.
len The length of buf in bytes.
log_stderr
int (*log_stderr)(const char *buf, unsigned int len);
The 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
command) or -1 if an error occurred.
The function arguments are as follows:
buf The buffer containing command output.
len The length of buf in bytes.
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register_hooks
See the Policy plugin API section for a description of
register_hooks.
deregister_hooks
See the Policy plugin API section for a description of
deregister_hooks.
I/O Plugin Version Macros
Same as for the Policy plugin API.
Hook function API
Beginning with plugin API version 1.2, it is possible to
install hooks for certain functions called by the sudo front
end.
Currently, the only supported hooks relate to the handling
of environment variables. Hooks can be used to intercept
attempts to get, set, or remove environment variables so
that these changes can be reflected in the version of the
environment that is used to execute a command. A future
version of the API will support hooking internal sudo front
end functions as well.
Hook structure
Hooks in sudo are described by the following structure:
typedef int (*sudo_hook_fn_t)();
struct sudo_hook {
int hook_version;
int hook_type;
sudo_hook_fn_t hook_fn;
void *closure;
};
The sudo_hook structure has the following fields:
hook_version
The hook_version field should be set to
SUDO_HOOK_VERSION.
hook_type
The hook_type field may be one of the following
supported hook types:
SUDO_HOOK_SETENV
The C library setenv(3) function. Any
registered hooks will run before the C library
implementation. The hook_fn field should be a
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function that matches the following typedef:
typedef int (*sudo_hook_fn_setenv_t)(const char *name,
const char *value, int overwrite, void *closure);
If the registered hook does not match the
typedef the results are unspecified.
SUDO_HOOK_UNSETENV
The C library unsetenv(3) function. Any
registered hooks will run before the C library
implementation. The hook_fn field should be a
function that matches the following typedef:
typedef int (*sudo_hook_fn_unsetenv_t)(const char *name,
void *closure);
SUDO_HOOK_GETENV
The C library getenv(3) function. Any
registered hooks will run before the C library
implementation. The hook_fn field should be a
function that matches the following typedef:
typedef int (*sudo_hook_fn_getenv_t)(const char *name,
char **value, void *closure);
If the registered hook does not match the
typedef the results are unspecified.
SUDO_HOOK_PUTENV
The C library putenv(3) function. Any
registered hooks will run before the C library
implementation. The hook_fn field should be a
function that matches the following typedef:
typedef int (*sudo_hook_fn_putenv_t)(char *string,
void *closure);
If the registered hook does not match the
typedef the results are unspecified.
hook_fn
sudo_hook_fn_t hook_fn;
The hook_fn field should be set to the plugin's hook
implementation. The actual function arguments will
vary depending on the hook_type (see hook_type above).
In all cases, the closure field of struct sudo_hook is
passed as the last function parameter. This can be
used to pass arbitrary data to the plugin's hook
implementation.
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The function return value may be one of the following:
SUDO_HOOK_RET_ERROR
The hook function encountered an error.
SUDO_HOOK_RET_NEXT
The hook completed without error, go on to the
next hook (including the native implementation
if applicable). For example, a getenv(3) hook
might return SUDO_HOOK_RET_NEXT if the specified
variable was not found in the private copy of
the environment.
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 setenv hook that operates on a
private copy of the environment but leaves
environ unchanged.
Note that it is very easy to create an infinite loop when
hooking C library functions. For example, a getenv(3) hook
that calls the snprintf(3) function may create a loop if the
snprintf(3) implementation calls 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:
static int in_progress = 0; /* avoid recursion */
if (in_progress)
return SUDO_HOOK_RET_NEXT;
in_progress = 1;
...
in_progress = 0;
return SUDO_HOOK_RET_STOP;
Hook API Version Macros
/* Hook API version major/minor */
#define SUDO_HOOK_VERSION_MAJOR 1
#define SUDO_HOOK_VERSION_MINOR 0
#define SUDO_HOOK_MKVERSION(x, y) ((x << 16) | y)
#define SUDO_HOOK_VERSION SUDO_HOOK_MKVERSION(SUDO_HOOK_VERSION_MAJOR,\
SUDO_HOOK_VERSION_MINOR)
/* Getters and setters for hook API version */
#define SUDO_HOOK_VERSION_GET_MAJOR(v) ((v) >> 16)
#define SUDO_HOOK_VERSION_GET_MINOR(v) ((v) & 0xffff)
#define SUDO_HOOK_VERSION_SET_MAJOR(vp, n) do { \
*(vp) = (*(vp) & 0x0000ffff) | ((n) << 16); \
} while(0)
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#define SUDO_HOOK_VERSION_SET_MINOR(vp, n) do { \
*(vp) = (*(vp) & 0xffff0000) | (n); \
} while(0)
Conversation API
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 msg if one is to
be printed.
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.
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_DEBUG_MSG 0x0006 /* debugging message */
#define SUDO_CONV_PROMPT_ECHO_OK 0x1000 /* flag: allow echo if no tty */
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, ...);
Pointers to the conversation() and printf()-style functions
are passed in to the plugin's open() function when the
plugin is initialized.
To use the conversation() function, the plugin must pass an
array of sudo_conv_message and sudo_conv_reply structures.
There must be a struct sudo_conv_message and struct
sudo_conv_reply for each message in the conversation. The
plugin is responsible for freeing the reply buffer filled in
to the struct sudo_conv_reply, if any.
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The printf()-style function uses the same underlying
mechanism as the conversation() function but only supports
SUDO_CONV_INFO_MSG, SUDO_CONV_ERROR_MSG and
SUDO_CONV_DEBUG_MSG for the msg_type parameter. It can be
more convenient than using the conversation() function if no
user reply is needed and supports standard printf() escape
sequences.
Unlike, SUDO_CONV_INFO_MSG and Dv SUDO_CONV_ERROR_MSG ,
messages sent with the SUDO_CONV_DEBUG_MSG msg_type are not
directly user-visible. Instead, they are logged to the file
specified in the Debug statement (if any) in the
/etc/sudo.conf
file. This allows a plugin to log debugging information and
is intended to be used in conjunction with the debug_flags
setting.
See the sample plugin for an example of the conversation()
function usage.
Sudoers group plugin API
The sudoers module supports a plugin interface to allow non-
Unix group lookups. This can be used to query a group
source other than the standard Unix group database. A
sample group plugin is bundled with sudo that implements
file-based lookups. Third party group plugins include a QAS
AD plugin available from Quest Software.
A group plugin must declare and populate a
sudoers_group_plugin struct in the global scope. This
structure contains pointers to the functions that implement
plugin initialization, cleanup and group lookup.
struct sudoers_group_plugin {
unsigned int version;
int (*init)(int version, sudo_printf_t sudo_printf,
char *const argv[]);
void (*cleanup)(void);
int (*query)(const char *user, const char *group,
const struct passwd *pwd);
};
The sudoers_group_plugin struct has the following fields:
version
The version field should be set to GROUP_API_VERSION.
This allows sudoers to determine the API version the
group plugin was built against.
init
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int (*init)(int version, sudo_printf_t plugin_printf,
char *const argv[]);
The init() function is called after 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 plugin_printf()
function with SUDO_CONF_ERROR_MSG to present
additional error information to the user.
The function arguments are as follows:
version
The version passed in by sudoers allows the
plugin to determine the major and minor version
number of the group plugin API supported by
sudoers.
plugin_printf
A pointer to a printf()-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.
argv A NULL-terminated array of arguments generated
from the group_plugin option in sudoers. If no
arguments were given, argv will be NULL.
cleanup
void (*cleanup)();
The cleanup() function is called when sudoers has
finished its group checks. The plugin should free any
memory it has allocated and close open file handles.
query
int (*query)(const char *user, const char *group,
const struct passwd *pwd);
The query() function is used to ask the group plugin
whether user is a member of group.
The function arguments are as follows:
user The name of the user being looked up in the
external group database.
group
The name of the group being queried.
pwd The password database entry for user, if any.
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If user is not present in the password database,
pwd will be NULL.
Group API Version Macros
/* Sudoers group plugin version major/minor */
#define GROUP_API_VERSION_MAJOR 1
#define GROUP_API_VERSION_MINOR 0
#define GROUP_API_VERSION ((GROUP_API_VERSION_MAJOR << 16) | \
GROUP_API_VERSION_MINOR)
/* Getters and setters for group version */
#define GROUP_API_VERSION_GET_MAJOR(v) ((v) >> 16)
#define GROUP_API_VERSION_GET_MINOR(v) ((v) & 0xffff)
#define GROUP_API_VERSION_SET_MAJOR(vp, n) do { \
*(vp) = (*(vp) & 0x0000ffff) | ((n) << 16); \
} while(0)
#define GROUP_API_VERSION_SET_MINOR(vp, n) do { \
*(vp) = (*(vp) & 0xffff0000) | (n); \
} while(0)
PLUGIN API CHANGELOG
The following revisions have been made to the Sudo Plugin
API.
Version 1.0
Initial API version.
Version 1.1
The I/O logging plugin's open() function was modified
to take the command_info list as an argument.
Version 1.2
The Policy and I/O logging plugins' open() functions
are now passed a list of plugin options if any are
specified in /etc/sudo.conf.
A simple hooks API has been introduced to allow
plugins to hook in to the system's environment
handling functions.
The 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.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
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+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | security/sudo |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
sudoers(4), sudo(1m)
BUGS
If you feel you have found a bug in sudo, please submit a
bug report at http://www.sudo.ws/sudo/bugs/
SUPPORT
Limited free support is available via the sudo-users mailing
list, see http://www.sudo.ws/mailman/listinfo/sudo-users to
subscribe or search the archives.
DISCLAIMER
sudo is provided ``AS IS'' and any express or implied
warranties, including, but not limited to, the implied
warranties of merchantability and fitness for a particular
purpose are disclaimed. See the LICENSE file distributed
with sudo or http://www.sudo.ws/sudo/license.html for
complete details.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.sudo.ws/sudo/dist/sudo-1.8.6p7.tar.gz
Further information about this software can be found on the
open source community website at http://www.sudo.ws/.
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