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# Copyright 2016, Tresys Technology, LLC
# Copyright 2018, Chris PeBenito <pebenito@ieee.org>
#
# 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 defaultdict, namedtuple
from .. import MLSRuletype
from .descriptors import DiffResultDescriptor
from .difference import Difference, Wrapper
from .mls import RangeWrapper
from .objclass import class_wrapper_factory
from .types import type_or_attr_wrapper_factory
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_mls_rules = defaultdict(list)
_right_mls_rules = defaultdict(list)
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 not self._left_mls_rules or not self._right_mls_rules:
self._create_mls_rule_lists()
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 = []
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))
self.added_range_transitions = added
self.removed_range_transitions = removed
self.modified_range_transitions = modified
#
# Internal functions
#
def _create_mls_rule_lists(self):
"""Create rule lists for both policies."""
# do not expand yet, to keep memory
# use down as long as possible
self.log.debug("Building MLS rule lists from {0.left_policy}".format(self))
for rule in self.left_policy.mlsrules():
self._left_mls_rules[rule.ruletype].append(rule)
self.log.debug("Building MLS rule lists from {0.right_policy}".format(self))
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):
"""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_mls_rules.clear()
self._right_mls_rules.clear()
class MLSRuleWrapper(Wrapper):
"""Wrap MLS rules to allow set operations."""
__slots__ = ("ruletype", "source", "target", "tclass")
def __init__(self, rule):
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