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# -*- coding: utf-8 -*-
# slip.dbus.polkit -- convenience decorators and functions for using PolicyKit
# with dbus services and clients
#
# Copyright © 2008, 2009, 2012, 2013, 2015 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# Authors:
# Nils Philippsen <nils@redhat.com>
"""This module contains convenience decorators and functions for using
PolicyKit with dbus services and clients."""
from __future__ import absolute_import
import collections
import dbus
from decorator import decorator
from functools import reduce
from .constants import method_call_no_timeout
__all__ = ["require_auth", "enable_proxy", "AUTHFAIL_DONTCATCH",
"NotAuthorizedException", "AreAuthorizationsObtainable",
"IsSystemBusNameAuthorizedAsync"]
def require_auth(polkit_auth):
"""Decorator for DBus service methods.
Specify that a user needs a specific PolicyKit authorization `polkit_auth´
to execute it."""
def require_auth_decorator(method):
assert hasattr(method, "_dbus_is_method")
setattr(method, "_slip_polkit_auth_required", polkit_auth)
return method
return require_auth_decorator
AUTH_EXC_PREFIX = \
"org.fedoraproject.slip.dbus.service.PolKit.NotAuthorizedException."
class AUTHFAIL_DONTCATCH(object):
pass
def enable_proxy(
func=None, authfail_result=AUTHFAIL_DONTCATCH, authfail_exception=None,
authfail_callback=None):
"""Decorator for DBus proxy methods.
Let's you (optionally) specify either a result value or an exception type
and a callback which is returned, thrown or called respectively if a
PolicyKit authorization doesn't exist or can't be obtained in the DBus
mechanism, i.e. an appropriate DBus exception is thrown.
An exception constructor may and a callback must accept an `action_id´
parameter which will be set to the id of the PolicyKit action for which
authorization could not be obtained.
Examples:
1) Return `False´ in the event of an authorization problem, and call
`error_handler´:
def error_handler(action_id=None):
print "Authorization problem:", action_id
class MyProxy(object):
@polkit.enable_proxy(authfail_result=False,
authfail_callback=error_handler)
def some_method(self, ...):
...
2) Throw a `MyAuthError´ instance in the event of an authorization problem:
class MyAuthError(Exception):
def __init__(self, *args, **kwargs):
action_id = kwargs.pop("action_id")
super(MyAuthError, self).__init__(*args, **kwargs)
self.action_id = action_id
class MyProxy(object):
@polkit.enable_proxy(authfail_exception=MyAuthError)
def some_method(self, ...):
..."""
assert(func is None or isinstance(func, collections.Callable))
assert(
authfail_result in (None, AUTHFAIL_DONTCATCH) or
authfail_exception is None)
assert(
authfail_callback is None or
isinstance(authfail_callback, collections.Callable))
assert(
authfail_exception is None or
issubclass(authfail_exception, Exception))
def _enable_proxy(func, *p, **k):
try:
return func(*p, **k)
except dbus.DBusException as e:
exc_name = e.get_dbus_name()
if not exc_name.startswith(AUTH_EXC_PREFIX):
raise
action_id = exc_name[len(AUTH_EXC_PREFIX):]
if authfail_callback is not None:
authfail_callback(action_id=action_id)
if authfail_exception is not None:
try:
af_exc = authfail_exception(action_id=action_id)
except:
af_exc = authfail_exception()
raise af_exc
if authfail_result is AUTHFAIL_DONTCATCH:
raise
return authfail_result
if func is not None:
return decorator(_enable_proxy, func)
else:
def decorate(func):
return decorator(_enable_proxy, func)
return decorate
class NotAuthorizedException(dbus.DBusException):
"""Exception which a DBus service method throws if an authorization
required for executing it can't be obtained."""
_dbus_error_name = \
"org.fedoraproject.slip.dbus.service.PolKit.NotAuthorizedException"
def __init__(self, action_id, *p, **k):
self._dbus_error_name = self.__class__._dbus_error_name + "." +\
action_id
super(NotAuthorizedException, self).__init__(*p, **k)
class PolKit(object):
"""Convenience wrapper around polkit."""
_dbus_name = 'org.freedesktop.PolicyKit1'
_dbus_path = '/org/freedesktop/PolicyKit1/Authority'
_dbus_interface = 'org.freedesktop.PolicyKit1.Authority'
__interface = None
__bus = None
__bus_name = None
__signal_receiver = None
@classmethod
def _on_name_owner_changed(cls, name, old_owner, new_owner):
if name == cls._dbus_name and PolKit.__bus:
PolKit.__bus.remove_signal_receiver(PolKit.__signal_receiver)
PolKit.__bus = None
PolKit.__signal_receiver = None
PolKit.__interface = None
@property
def _bus(self):
if not PolKit.__bus:
PolKit.__bus = dbus.SystemBus()
PolKit.__signal_receiver = PolKit.__bus.add_signal_receiver(
handler_function=self._on_name_owner_changed,
signal_name='NameOwnerChanged',
dbus_interface='org.freedesktop.DBus',
arg0=self._dbus_name)
return PolKit.__bus
@property
def _bus_name(self):
if not PolKit.__bus_name:
PolKit.__bus_name = self._bus.get_unique_name()
return PolKit.__bus_name
@property
def _interface(self):
if not PolKit.__interface:
try:
PolKit.__interface = dbus.Interface(self._bus.get_object(
self._dbus_name, self._dbus_path),
self._dbus_interface)
except dbus.DBusException:
pass
return PolKit.__interface
@property
def _polkit_present(self):
return bool(self._interface)
def __dbus_system_bus_name_uid(self, system_bus_name):
bus_object = self._bus.get_object(
'org.freedesktop.DBus', '/org/freedesktop/DBus')
bus_interface = dbus.Interface(bus_object, 'org.freedesktop.DBus')
try:
uid = bus_interface.GetConnectionUnixUser(system_bus_name)
except:
uid = None
return uid
def __authorization_is_obtainable(self, authorization):
if not self._polkit_present:
return True
(is_authorized, is_challenge, details) = \
self._interface.CheckAuthorization(
("system-bus-name", {"name": self._bus_name}),
authorization, {}, 0, "")
return is_authorized or is_challenge
def AreAuthorizationsObtainable(self, authorizations):
if not self._polkit_present:
return True
if not isinstance(authorizations, (tuple, list, set)):
authorizations = (authorizations,)
obtainable = \
reduce(
lambda x, y: x and self.__authorization_is_obtainable(y),
authorizations, True)
return obtainable
def IsSystemBusNameAuthorizedAsync(
self, system_bus_name, action_id, reply_handler, error_handler,
challenge=True, details={}):
if not self._polkit_present:
return reply_handler(action_id is None or
self.__dbus_system_bus_name_uid(system_bus_name) == 0)
flags = 0
if challenge:
flags |= 0x1
def reply_cb(args):
(is_authorized, is_challenge, details) = args
reply_handler(is_authorized)
self._interface.CheckAuthorization(
("system-bus-name", {"name": system_bus_name}),
action_id, details, flags, "",
reply_handler=reply_cb, error_handler=error_handler,
timeout=method_call_no_timeout)
__polkit = PolKit()
def AreAuthorizationsObtainable(authorizations):
return __polkit.AreAuthorizationsObtainable(authorizations)
def IsSystemBusNameAuthorizedAsync(
system_bus_name, action_id, reply_handler, error_handler, challenge=True,
details={}):
return __polkit.IsSystemBusNameAuthorizedAsync(
system_bus_name, action_id, reply_handler, error_handler, challenge,
details)