# 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
from ..policyrep import AnyRBACRule, RBACRuletype, Role, RoleAllow, RoleTransition
from .descriptors import DiffResultDescriptor
from .difference import Difference, Wrapper
from .objclass import class_wrapper_factory
from .roles import role_wrapper_factory
from .types import type_or_attr_wrapper_factory
from .typing import RuleList
class ModifiedRBACRule(NamedTuple):
"""Difference details for a modified RBAC rule."""
rule: AnyRBACRule
added_default: Role
removed_default: Role
class RBACRulesDifference(Difference):
"""Determine the difference in RBAC rules between two policies."""
added_role_allows = DiffResultDescriptor("diff_role_allows")
removed_role_allows = DiffResultDescriptor("diff_role_allows")
# role allows cannot be modified, only added/removed
added_role_transitions = DiffResultDescriptor("diff_role_transitions")
removed_role_transitions = DiffResultDescriptor("diff_role_transitions")
modified_role_transitions = DiffResultDescriptor("diff_role_transitions")
# Lists of rules for each policy
_left_rbac_rules: RuleList[RBACRuletype, AnyRBACRule] = None
_right_rbac_rules: RuleList[RBACRuletype, AnyRBACRule] = None
def diff_role_allows(self) -> None:
"""Generate the difference in role allow rules between the policies."""
self.log.info(
"Generating role allow differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_rbac_rules is None or self._right_rbac_rules is None:
self._create_rbac_rule_lists()
assert self._left_rbac_rules is not None, "Left RBAC rules didn't load, this a bug."
assert self._right_rbac_rules is not None, "Right RBAC rules didn't load, this a bug."
self.added_role_allows, self.removed_role_allows, _ = self._set_diff(
self._expand_generator(self._left_rbac_rules[RBACRuletype.allow], RoleAllowWrapper),
self._expand_generator(self._right_rbac_rules[RBACRuletype.allow], RoleAllowWrapper))
def diff_role_transitions(self) -> None:
"""Generate the difference in role_transition rules between the policies."""
self.log.info(
"Generating role_transition differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_rbac_rules is None or self._right_rbac_rules is None:
self._create_rbac_rule_lists()
assert self._left_rbac_rules is not None, "Left RBAC rules didn't load, this a bug."
assert self._right_rbac_rules is not None, "Right RBAC rules didn't load, this a bug."
added, removed, matched = self._set_diff(
self._expand_generator(self._left_rbac_rules[RBACRuletype.role_transition],
RoleTransitionWrapper),
self._expand_generator(self._right_rbac_rules[RBACRuletype.role_transition],
RoleTransitionWrapper))
modified = []
for left_rule, right_rule in matched:
# Criteria for modified rules
# 1. change to default role
if role_wrapper_factory(left_rule.default) != role_wrapper_factory(right_rule.default):
modified.append(ModifiedRBACRule(left_rule,
right_rule.default,
left_rule.default))
self.added_role_transitions = added
self.removed_role_transitions = removed
self.modified_role_transitions = modified
#
# Internal functions
#
def _create_rbac_rule_lists(self) -> None:
"""Create rule lists for both policies."""
# do not expand yet, to keep memory
# use down as long as possible
self._left_rbac_rules = defaultdict(list)
self.log.debug("Building RBAC rule lists from {0.left_policy}".format(self))
for rule in self.left_policy.rbacrules():
self._left_rbac_rules[rule.ruletype].append(rule)
self._right_rbac_rules = defaultdict(list)
self.log.debug("Building RBAC rule lists from {0.right_policy}".format(self))
for rule in self.right_policy.rbacrules():
self._right_rbac_rules[rule.ruletype].append(rule)
self.log.debug("Completed building RBAC rule lists.")
def _reset_diff(self) -> None:
"""Reset diff results on policy changes."""
self.log.debug("Resetting RBAC rule differences")
self.added_role_allows = None
self.removed_role_allows = None
self.added_role_transitions = None
self.removed_role_transitions = None
self.modified_role_transitions = None
# Sets of rules for each policy
self._left_rbac_rules = None
self._right_rbac_rules = None
class RoleAllowWrapper(Wrapper[RoleAllow]):
"""Wrap role allow rules to allow set operations."""
__slots__ = ("source", "target")
def __init__(self, rule: RoleAllow) -> None:
self.origin = rule
self.source = role_wrapper_factory(rule.source)
self.target = role_wrapper_factory(rule.target)
self.key = hash(rule)
def __hash__(self):
return self.key
def __lt__(self, other):
return self.key < other.key
def __eq__(self, other):
# because RBACRuleDifference groups rules by ruletype,
# the ruletype always matches.
return self.source == other.source and self.target == other.target
class RoleTransitionWrapper(Wrapper[RoleTransition]):
"""Wrap role_transition rules to allow set operations."""
__slots__ = ("source", "target", "tclass")
def __init__(self, rule: RoleTransition) -> None:
self.origin = rule
self.source = role_wrapper_factory(rule.source)
self.target = type_or_attr_wrapper_factory(rule.target)
self.tclass = class_wrapper_factory(rule.tclass)
self.key = hash(rule)
def __hash__(self):
return self.key
def __lt__(self, other):
return self.key < other.key
def __eq__(self, other):
# because RBACRuleDifference groups rules by ruletype,
# the ruletype always matches.
return self.source == other.source and \
self.target == other.target and \
self.tclass == other.tclass
