| # Copyright 2014, 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/>. |
| # |
| import itertools |
| |
| from . import exception |
| from . import qpol |
| from . import rule |
| from . import typeattr |
| from . import mls |
| |
| |
| def mls_rule_factory(policy, symbol): |
| """Factory function for creating MLS rule objects.""" |
| if not isinstance(symbol, qpol.qpol_range_trans_t): |
| raise TypeError("MLS rules cannot be looked-up.") |
| |
| return MLSRule(policy, symbol) |
| |
| |
| def expanded_mls_rule_factory(original, source, target): |
| """ |
| Factory function for creating expanded MLS rules. |
| |
| original The MLS rule the expanded rule originates from. |
| source The source type of the expanded rule. |
| target The target type of the expanded rule. |
| """ |
| |
| if isinstance(original, MLSRule): |
| rule = ExpandedMLSRule(original.policy, original.qpol_symbol) |
| elif isinstance(original, MLSRule): |
| return original |
| else: |
| raise TypeError("The original rule must be a MLS rule class.") |
| |
| rule.source = source |
| rule.target = target |
| rule.origin = original |
| return rule |
| |
| |
| def validate_ruletype(t): |
| """Validate MLS rule types.""" |
| if t not in ["range_transition"]: |
| raise exception.InvalidMLSRuleType("{0} is not a valid MLS rule type.".format(t)) |
| |
| return t |
| |
| |
| class MLSRule(rule.PolicyRule): |
| |
| """An MLS rule.""" |
| |
| def __str__(self): |
| return "{0.ruletype} {0.source} {0.target}:{0.tclass} {0.default};".format(self) |
| |
| ruletype = "range_transition" |
| |
| @property |
| def source(self): |
| """The rule's source type/attribute.""" |
| return typeattr.type_or_attr_factory(self.policy, self.qpol_symbol.source_type(self.policy)) |
| |
| @property |
| def target(self): |
| """The rule's target type/attribute.""" |
| return typeattr.type_or_attr_factory(self.policy, self.qpol_symbol.target_type(self.policy)) |
| |
| @property |
| def default(self): |
| """The rule's default range.""" |
| return mls.range_factory(self.policy, self.qpol_symbol.range(self.policy)) |
| |
| def expand(self): |
| """Expand the rule into an equivalent set of rules without attributes.""" |
| for s, t in itertools.product(self.source.expand(), self.target.expand()): |
| yield expanded_mls_rule_factory(self, s, t) |
| |
| |
| class ExpandedMLSRule(MLSRule): |
| |
| """An expanded MLS rule.""" |
| |
| source = None |
| target = None |
| origin = None |