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Editing: mlsrules.py
# Copyright 2016, Tresys Technology, LLC # Copyright 2018, Chris PeBenito <pebenito@ieee.org> # # SPDX-License-Identifier: LGPL-2.1-only # from collections import defaultdict from dataclasses import dataclass from ..policyrep import MLSRule, MLSRuletype, Range from .descriptors import DiffResultDescriptor from .difference import Difference, DifferenceResult, Wrapper from .mls import RangeWrapper from .objclass import class_wrapper_factory from .types import type_or_attr_wrapper_factory from .typing import RuleList @dataclass(frozen=True, order=True) class ModifiedMLSRule(DifferenceResult): """Difference details for a modified MLS rule.""" rule: MLSRule added_default: Range removed_default: Range class MLSRulesDifference(Difference): """Determine the difference in MLS rules between two policies.""" def diff_range_transitions(self) -> None: """Generate the difference in range_transition rules between the policies.""" self.log.info( f"Generating range_transition differences from {self.left_policy} " f"to {self.right_policy}") if self._left_mls_rules is None or self._right_mls_rules is None: self._create_mls_rule_lists() assert self._left_mls_rules is not None, "Left MLS rules did not load, this is a bug." assert self._right_mls_rules is not None, "Right MLS rules did not load, this is a bug." added, removed, matched = self._set_diff( self._expand_generator(self._left_mls_rules[MLSRuletype.range_transition], MLSRuleWrapper), self._expand_generator(self._right_mls_rules[MLSRuletype.range_transition], MLSRuleWrapper)) modified = list[ModifiedMLSRule]() for left_rule, right_rule in matched: # Criteria for modified rules # 1. change to default range if RangeWrapper(left_rule.default) != RangeWrapper(right_rule.default): modified.append(ModifiedMLSRule(left_rule, right_rule.default, left_rule.default)) self.added_range_transitions = added self.removed_range_transitions = removed self.modified_range_transitions = modified added_range_transitions = DiffResultDescriptor[MLSRule](diff_range_transitions) removed_range_transitions = DiffResultDescriptor[MLSRule](diff_range_transitions) modified_range_transitions = DiffResultDescriptor[ModifiedMLSRule](diff_range_transitions) # Lists of rules for each policy _left_mls_rules: RuleList[MLSRuletype, MLSRule] = None _right_mls_rules: RuleList[MLSRuletype, MLSRule] = None # # Internal functions # def _create_mls_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_mls_rules = defaultdict(list) self.log.debug(f"Building MLS rule lists from {self.left_policy}") for rule in self.left_policy.mlsrules(): self._left_mls_rules[rule.ruletype].append(rule) self._right_mls_rules = defaultdict(list) self.log.debug(f"Building MLS rule lists from {self.right_policy}") for rule in self.right_policy.mlsrules(): self._right_mls_rules[rule.ruletype].append(rule) self.log.debug("Completed building MLS rule lists.") def _reset_diff(self) -> None: """Reset diff results on policy changes.""" self.log.debug("Resetting MLS rule differences") del self.added_range_transitions del self.removed_range_transitions del self.modified_range_transitions # Sets of rules for each policy self._left_mls_rules = None self._right_mls_rules = None class MLSRuleWrapper(Wrapper[MLSRule]): """Wrap MLS rules to allow set operations.""" __slots__ = ("ruletype", "source", "target", "tclass") def __init__(self, rule: MLSRule) -> None: self.origin = rule self.source = type_or_attr_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 MLSRuleDifference groups rules by ruletype, # the ruletype always matches. return self.source == other.source and \ self.target == other.target and \ self.tclass == other.tclass
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