| # Copyright 2016, Tresys Technology, LLC |
| # |
| # This file is part of SETools. |
| # |
| # SETools is free software: you can redistribute it and/or modify |
| # it under the terms of the GNU Lesser General Public License as |
| # published by the Free Software Foundation, either version 2.1 of |
| # the License, or (at your option) any later version. |
| # |
| # SETools 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 Lesser General Public License for more details. |
| # |
| # You should have received a copy of the GNU Lesser General Public |
| # License along with SETools. If not, see |
| # <http://www.gnu.org/licenses/>. |
| # |
| from collections import namedtuple |
| |
| from .descriptors import DiffResultDescriptor |
| from .difference import Difference, SymbolWrapper, Wrapper |
| from .mls import RangeWrapper |
| |
| |
| modified_mlsrule_record = namedtuple("modified_mlsrule", ["rule", |
| "added_default", |
| "removed_default"]) |
| |
| |
| class MLSRulesDifference(Difference): |
| |
| """Determine the difference in MLS rules between two policies.""" |
| |
| added_range_transitions = DiffResultDescriptor("diff_range_transitions") |
| removed_range_transitions = DiffResultDescriptor("diff_range_transitions") |
| modified_range_transitions = DiffResultDescriptor("diff_range_transitions") |
| |
| # Lists of rules for each policy |
| _left_range_transitions = None |
| _right_range_transitions = None |
| |
| def diff_range_transitions(self): |
| """Generate the difference in range_transition rules between the policies.""" |
| |
| self.log.info( |
| "Generating range_transition differences from {0.left_policy} to {0.right_policy}". |
| format(self)) |
| |
| if self._left_range_transitions is None or self._right_range_transitions is None: |
| self._create_mls_rule_lists() |
| |
| self.added_range_transitions, \ |
| self.removed_range_transitions, \ |
| self.modified_range_transitions = self._diff_mls_rules( |
| self._expand_generator(self._left_range_transitions, MLSRuleWrapper), |
| self._expand_generator(self._right_range_transitions, MLSRuleWrapper)) |
| |
| # |
| # Internal functions |
| # |
| def _create_mls_rule_lists(self): |
| """Create rule lists for both policies.""" |
| self._left_range_transitions = [] |
| for rule in self.left_policy.mlsrules(): |
| # do not expand yet, to keep memory |
| # use down as long as possible |
| if rule.ruletype == "range_transition": |
| self._left_range_transitions.append(rule) |
| else: |
| self.log.error("Unknown rule type: {0} (This is an SETools bug)". |
| format(rule.ruletype)) |
| |
| self._right_range_transitions = [] |
| for rule in self.right_policy.mlsrules(): |
| # do not expand yet, to keep memory |
| # use down as long as possible |
| if rule.ruletype == "range_transition": |
| self._right_range_transitions.append(rule) |
| else: |
| self.log.error("Unknown rule type: {0} (This is an SETools bug)". |
| format(rule.ruletype)) |
| |
| def _diff_mls_rules(self, left_list, right_list): |
| """Common method for comparing type_* rules.""" |
| added, removed, matched = self._set_diff(left_list, right_list) |
| |
| modified = [] |
| |
| 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(modified_mlsrule_record(left_rule, |
| right_rule.default, |
| left_rule.default)) |
| |
| return added, removed, modified |
| |
| def _reset_diff(self): |
| """Reset diff results on policy changes.""" |
| self.log.debug("Resetting MLS rule differences") |
| self.added_range_transitions = None |
| self.removed_range_transitions = None |
| self.modified_range_transitions = None |
| |
| # Sets of rules for each policy |
| self._left_range_transitions = None |
| self._right_range_transitions = None |
| |
| |
| class MLSRuleWrapper(Wrapper): |
| |
| """Wrap MLS rules to allow set operations.""" |
| |
| def __init__(self, rule): |
| self.origin = rule |
| self.ruletype = rule.ruletype |
| self.source = SymbolWrapper(rule.source) |
| self.target = SymbolWrapper(rule.target) |
| self.tclass = SymbolWrapper(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 |
