# Copyright 2016, Tresys Technology, LLC
# Copyright 2018, Chris PeBenito <pebenito@ieee.org>
#
# SPDX-License-Identifier: LGPL-2.1-only
#
from collections import defaultdict
from typing import NamedTuple, Set, Optional, Union
from ..exception import MLSDisabled
from ..policyrep import Level, Range, Role, User
from .descriptors import DiffResultDescriptor
from .difference import Difference, SymbolWrapper
from .mls import LevelWrapper, RangeWrapper
from .roles import role_wrapper_factory
from .typing import SymbolCache
_users_cache: SymbolCache[User] = defaultdict(dict)
class ModifiedUser(NamedTuple):
"""Difference details for a modified user."""
added_roles: Set[Role]
removed_roles: Set[Role]
matched_roles: Set[Role]
added_level: Optional[Union[Level, str]]
removed_level: Optional[Union[Level, str]]
added_range: Optional[Union[Range, str]]
removed_range: Optional[Union[Range, str]]
def user_wrapper_factory(user: User) -> SymbolWrapper[User]:
"""
Wrap users from the specified policy.
This caches results to prevent duplicate wrapper
objects in memory.
"""
try:
return _users_cache[user.policy][user]
except KeyError:
r = SymbolWrapper(user)
_users_cache[user.policy][user] = r
return r
class UsersDifference(Difference):
"""Determine the difference in users between two policies."""
added_users = DiffResultDescriptor("diff_users")
removed_users = DiffResultDescriptor("diff_users")
modified_users = DiffResultDescriptor("diff_users")
def diff_users(self) -> None:
"""Generate the difference in users between the policies."""
self.log.info(
"Generating user differences from {0.left_policy} to {0.right_policy}".format(self))
self.added_users, self.removed_users, matched_users = self._set_diff(
(user_wrapper_factory(r) for r in self.left_policy.users()),
(user_wrapper_factory(r) for r in self.right_policy.users()))
self.modified_users = dict()
for left_user, right_user in matched_users:
# Criteria for modified users
# 1. change to role set, or
# 2. change to default level, or
# 3. change to range
added_roles, removed_roles, matched_roles = self._set_diff(
(role_wrapper_factory(r) for r in left_user.roles),
(role_wrapper_factory(r) for r in right_user.roles))
# keep wrapped and unwrapped MLS objects here so there
# are not several nested try blocks
left_level_wrap: Optional[LevelWrapper]
left_range_wrap: Optional[RangeWrapper]
left_level: Union[Level, str]
left_range: Union[Range, str]
right_level_wrap: Optional[LevelWrapper]
right_range_wrap: Optional[RangeWrapper]
right_level: Union[Level, str]
right_range: Union[Range, str]
added_level: Optional[Union[Level, str]]
added_range: Optional[Union[Range, str]]
removed_level: Optional[Union[Level, str]]
removed_range: Optional[Union[Range, str]]
try:
left_level_wrap = LevelWrapper(left_user.mls_level)
left_range_wrap = RangeWrapper(left_user.mls_range)
left_level = left_user.mls_level
left_range = left_user.mls_range
except MLSDisabled:
left_level_wrap = None
left_range_wrap = None
left_level = "None (MLS Disabled)"
left_range = "None (MLS Disabled)"
try:
right_level_wrap = LevelWrapper(right_user.mls_level)
right_range_wrap = RangeWrapper(right_user.mls_range)
right_level = right_user.mls_level
right_range = right_user.mls_range
except MLSDisabled:
right_level_wrap = None
right_range_wrap = None
right_level = "None (MLS Disabled)"
right_range = "None (MLS Disabled)"
if left_level_wrap != right_level_wrap:
added_level = right_level
removed_level = left_level
else:
added_level = None
removed_level = None
if left_range_wrap != right_range_wrap:
added_range = right_range
removed_range = left_range
else:
added_range = None
removed_range = None
if added_roles or removed_roles or removed_level or removed_range:
self.modified_users[left_user] = ModifiedUser(added_roles,
removed_roles,
matched_roles,
added_level,
removed_level,
added_range,
removed_range)
#
# Internal functions
#
def _reset_diff(self) -> None:
"""Reset diff results on policy changes."""
self.log.debug("Resetting user differences")
self.added_users = None
self.removed_users = None
self.modified_users = None
