1 # Copyright 2016, Tresys Technology, LLC 2 # 3 # This file is part of SETools. 4 # 5 # SETools is free software: you can redistribute it and/or modify 6 # it under the terms of the GNU Lesser General Public License as 7 # published by the Free Software Foundation, either version 2.1 of 8 # the License, or (at your option) any later version. 9 # 10 # SETools is distributed in the hope that it will be useful, 11 # but WITHOUT ANY WARRANTY; without even the implied warranty of 12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 # GNU Lesser General Public License for more details. 14 # 15 # You should have received a copy of the GNU Lesser General Public 16 # License along with SETools. If not, see 17 # <http://www.gnu.org/licenses/>. 18 # 19 from collections import defaultdict, namedtuple 20 21 from .descriptors import DiffResultDescriptor 22 from .difference import Difference, SymbolWrapper, Wrapper 23 from .mls import RangeWrapper 24 25 26 modified_mlsrule_record = namedtuple("modified_mlsrule", ["rule", 27 "added_default", 28 "removed_default"]) 29 30 31 class MLSRulesDifference(Difference): 32 33 """Determine the difference in MLS rules between two policies.""" 34 35 added_range_transitions = DiffResultDescriptor("diff_range_transitions") 36 removed_range_transitions = DiffResultDescriptor("diff_range_transitions") 37 modified_range_transitions = DiffResultDescriptor("diff_range_transitions") 38 39 # Lists of rules for each policy 40 _left_mls_rules = defaultdict(list) 41 _right_mls_rules = defaultdict(list) 42 43 def diff_range_transitions(self): 44 """Generate the difference in range_transition rules between the policies.""" 45 46 self.log.info( 47 "Generating range_transition differences from {0.left_policy} to {0.right_policy}". 48 format(self)) 49 50 if not self._left_mls_rules or not self._right_mls_rules: 51 self._create_mls_rule_lists() 52 53 added, removed, matched = self._set_diff( 54 self._expand_generator(self._left_mls_rules["range_transition"], MLSRuleWrapper), 55 self._expand_generator(self._right_mls_rules["range_transition"], MLSRuleWrapper)) 56 57 modified = [] 58 59 for left_rule, right_rule in matched: 60 # Criteria for modified rules 61 # 1. change to default range 62 if RangeWrapper(left_rule.default) != RangeWrapper(right_rule.default): 63 modified.append(modified_mlsrule_record(left_rule, 64 right_rule.default, 65 left_rule.default)) 66 67 self.added_range_transitions = added 68 self.removed_range_transitions = removed 69 self.modified_range_transitions = modified 70 71 # 72 # Internal functions 73 # 74 def _create_mls_rule_lists(self): 75 """Create rule lists for both policies.""" 76 # do not expand yet, to keep memory 77 # use down as long as possible 78 self.log.debug("Building MLS rule lists from {0.left_policy}".format(self)) 79 for rule in self.left_policy.mlsrules(): 80 self._left_mls_rules[rule.ruletype].append(rule) 81 82 self.log.debug("Building MLS rule lists from {0.right_policy}".format(self)) 83 for rule in self.right_policy.mlsrules(): 84 self._right_mls_rules[rule.ruletype].append(rule) 85 86 self.log.debug("Completed building MLS rule lists.") 87 88 def _reset_diff(self): 89 """Reset diff results on policy changes.""" 90 self.log.debug("Resetting MLS rule differences") 91 self.added_range_transitions = None 92 self.removed_range_transitions = None 93 self.modified_range_transitions = None 94 95 # Sets of rules for each policy 96 self._left_mls_rules.clear() 97 self._right_mls_rules.clear() 98 99 100 class MLSRuleWrapper(Wrapper): 101 102 """Wrap MLS rules to allow set operations.""" 103 104 def __init__(self, rule): 105 self.origin = rule 106 self.ruletype = rule.ruletype 107 self.source = SymbolWrapper(rule.source) 108 self.target = SymbolWrapper(rule.target) 109 self.tclass = SymbolWrapper(rule.tclass) 110 self.key = hash(rule) 111 112 def __hash__(self): 113 return self.key 114 115 def __lt__(self, other): 116 return self.key < other.key 117 118 def __eq__(self, other): 119 # because MLSRuleDifference groups rules by ruletype, 120 # the ruletype always matches. 121 return self.source == other.source and \ 122 self.target == other.target and \ 123 self.tclass == other.tclass 124