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# 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
class ConstraintsDifference(Difference):
"""
Determine the difference in constraints between two policies.
Since the compiler does not union constraints, there may be multiple
constraints with the same ruletype, object class, and permission
set, so constraints can only be added or removed, not modified.
The constraint expressions are compared only on a basic level.
Expressions that are logically equivalent but are structurally
different, for example, by associativity, will be considered
different. Type and role attributes are also not expanded,
so if there are changes to attribute members, it will not
be reflected as a difference.
"""
added_constrains = DiffResultDescriptor("diff_constrains")
removed_constrains = DiffResultDescriptor("diff_constrains")
added_mlsconstrains = DiffResultDescriptor("diff_mlsconstrains")
removed_mlsconstrains = DiffResultDescriptor("diff_mlsconstrains")
added_validatetrans = DiffResultDescriptor("diff_validatetrans")
removed_validatetrans = DiffResultDescriptor("diff_validatetrans")
added_mlsvalidatetrans = DiffResultDescriptor("diff_mlsvalidatetrans")
removed_mlsvalidatetrans = DiffResultDescriptor("diff_mlsvalidatetrans")
# Lists of rules for each policy
_left_constrains = None
_right_constrains = None
_left_mlsconstrains = None
_right_mlsconstrains = None
_left_validatetrans = None
_right_validatetrans = None
_left_mlsvalidatetrans = None
_right_mlsvalidatetrans = None
def diff_constrains(self):
"""Generate the difference in constraint rules between the policies."""
self.log.info("Generating constraint differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_constrains is None or self._right_constrains is None:
self._create_constrain_lists()
self.added_constrains, self.removed_constrains, _ = self._set_diff(
(ConstraintWrapper(c) for c in self._left_constrains),
(ConstraintWrapper(c) for c in self._right_constrains))
def diff_mlsconstrains(self):
"""Generate the difference in MLS constraint rules between the policies."""
self.log.info(
"Generating MLS constraint differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_mlsconstrains is None or self._right_mlsconstrains is None:
self._create_constrain_lists()
self.added_mlsconstrains, self.removed_mlsconstrains, _ = self._set_diff(
(ConstraintWrapper(c) for c in self._left_mlsconstrains),
(ConstraintWrapper(c) for c in self._right_mlsconstrains))
def diff_validatetrans(self):
"""Generate the difference in validatetrans rules between the policies."""
self.log.info(
"Generating validatetrans differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_validatetrans is None or self._right_validatetrans is None:
self._create_constrain_lists()
self.added_validatetrans, self.removed_validatetrans, _ = self._set_diff(
(ConstraintWrapper(c) for c in self._left_validatetrans),
(ConstraintWrapper(c) for c in self._right_validatetrans))
def diff_mlsvalidatetrans(self):
"""Generate the difference in MLS validatetrans rules between the policies."""
self.log.info(
"Generating mlsvalidatetrans differences from {0.left_policy} to {0.right_policy}".
format(self))
if self._left_mlsvalidatetrans is None or self._right_mlsvalidatetrans is None:
self._create_constrain_lists()
self.added_mlsvalidatetrans, self.removed_mlsvalidatetrans, _ = self._set_diff(
(ConstraintWrapper(c) for c in self._left_mlsvalidatetrans),
(ConstraintWrapper(c) for c in self._right_mlsvalidatetrans))
#
# Internal functions
#
def _create_constrain_lists(self):
"""Create rule lists for both policies."""
self._left_constrains = []
self._left_mlsconstrains = []
self._left_validatetrans = []
self._left_mlsvalidatetrans = []
for rule in self.left_policy.constraints():
if rule.ruletype == "constrain":
self._left_constrains.append(rule)
elif rule.ruletype == "mlsconstrain":
self._left_mlsconstrains.append(rule)
elif rule.ruletype == "validatetrans":
self._left_validatetrans.append(rule)
elif rule.ruletype == "mlsvalidatetrans":
self._left_mlsvalidatetrans.append(rule)
else:
self.log.error("Unknown rule type: {0} (This is an SETools bug)".
format(rule.ruletype))
self._right_constrains = []
self._right_mlsconstrains = []
self._right_validatetrans = []
self._right_mlsvalidatetrans = []
for rule in self.right_policy.constraints():
if rule.ruletype == "constrain":
self._right_constrains.append(rule)
elif rule.ruletype == "mlsconstrain":
self._right_mlsconstrains.append(rule)
elif rule.ruletype == "validatetrans":
self._right_validatetrans.append(rule)
elif rule.ruletype == "mlsvalidatetrans":
self._right_mlsvalidatetrans.append(rule)
else:
self.log.error("Unknown rule type: {0} (This is an SETools bug)".
format(rule.ruletype))
def _reset_diff(self):
"""Reset diff results on policy changes."""
self.log.debug("Resetting all constraints differences")
self.added_constrains = None
self.removed_constrains = None
self.added_mlsconstrains = None
self.removed_mlsconstrains = None
self.added_validatetrans = None
self.removed_validatetrans = None
self.added_mlsvalidatetrans = None
self.removed_mlsvalidatetrans = None
# Sets of rules for each policy
self._left_constrains = None
self._left_mlsconstrains = None
self._left_validatetrans = None
self._left_mlsvalidatetrans = None
self._right_constrains = None
self._right_mlsconstrains = None
self._right_validatetrans = None
self._right_mlsvalidatetrans = None
class ConstraintWrapper(Wrapper):
"""Wrap constraints for diff purposes."""
def __init__(self, rule):
self.origin = rule
self.ruletype = rule.ruletype
self.tclass = SymbolWrapper(rule.tclass)
try:
self.perms = rule.perms
except AttributeError:
# (mls)validatetrans
self.perms = None
self.key = hash(rule)
self.expr = []
for op in rule.postfix_expression():
if isinstance(op, frozenset):
# lists of types/users/roles
self.expr.append(frozenset(SymbolWrapper(item) for item in op))
else:
# strings in the expression such as u1/r1/t1 or "=="
self.expr.append(op)
def __hash__(self):
return self.key
def __lt__(self, other):
return self.key < other.key
def __eq__(self, other):
return self.ruletype == other.ruletype and \
self.tclass == other.tclass and \
self.perms == other.perms and \
self.expr == other.expr
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