Current File : //lib64/python3.9/site-packages/setools/diff/objclass.py
# Copyright 2015, Tresys Technology, LLC
# Copyright 2018, Chris PeBenito <pebenito@ieee.org>
#
# SPDX-License-Identifier: LGPL-2.1-only
#
from collections import defaultdict
from contextlib import suppress
from typing import NamedTuple, Set
from ..exception import NoCommon
from ..policyrep import ObjClass
from .descriptors import DiffResultDescriptor
from .difference import Difference, SymbolWrapper
from .typing import SymbolCache
_class_cache: SymbolCache[ObjClass] = defaultdict(dict)
class ModifiedObjClass(NamedTuple):
"""Difference details for a modified object class."""
added_perms: Set[str]
removed_perms: Set[str]
matched_perms: Set[str]
def class_wrapper_factory(class_: ObjClass) -> SymbolWrapper[ObjClass]:
"""
Wrap class from the specified policy.
This caches results to prevent duplicate wrapper
objects in memory.
"""
try:
return _class_cache[class_.policy][class_]
except KeyError:
c = SymbolWrapper(class_)
_class_cache[class_.policy][class_] = c
return c
class ObjClassDifference(Difference):
"""
Determine the difference in object classes
between two policies.
"""
added_classes = DiffResultDescriptor("diff_classes")
removed_classes = DiffResultDescriptor("diff_classes")
modified_classes = DiffResultDescriptor("diff_classes")
def diff_classes(self) -> None:
"""Generate the difference in object classes between the policies."""
self.log.info(
"Generating class differences from {0.left_policy} to {0.right_policy}".format(self))
self.added_classes, self.removed_classes, matched_classes = self._set_diff(
(SymbolWrapper(c) for c in self.left_policy.classes()),
(SymbolWrapper(c) for c in self.right_policy.classes()))
self.modified_classes = dict()
for left_class, right_class in matched_classes:
# Criteria for modified classes
# 1. change to permissions (inherited common is expanded)
left_perms = left_class.perms
with suppress(NoCommon):
left_perms |= left_class.common.perms
right_perms = right_class.perms
with suppress(NoCommon):
right_perms |= right_class.common.perms
added_perms, removed_perms, matched_perms = self._set_diff(left_perms,
right_perms,
unwrap=False)
if added_perms or removed_perms:
self.modified_classes[left_class] = ModifiedObjClass(added_perms,
removed_perms,
matched_perms)
#
# Internal functions
#
def _reset_diff(self) -> None:
"""Reset diff results on policy changes."""
self.log.debug("Resetting object class differences")
self.added_classes = None
self.removed_classes = None
self.modified_classes = None
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