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# 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
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