# Copyright 2015, Tresys Technology, LLC
#
# SPDX-License-Identifier: LGPL-2.1-only
#
import logging
import re
from typing import Iterable, Set
from .descriptors import CriteriaDescriptor, CriteriaSetDescriptor
from .exception import ConstraintUseError
from .mixins import MatchObjClass, MatchPermission
from .policyrep import AnyConstraint, ConstraintRuletype
from .query import PolicyQuery
from .util import match_in_set
class ConstraintQuery(MatchObjClass, MatchPermission, PolicyQuery):
"""
Query constraint rules, (mls)constrain/(mls)validatetrans.
Parameter:
policy The policy to query.
Keyword Parameters/Class attributes:
ruletype The list of rule type(s) to match.
tclass The object class(es) to match.
tclass_regex If true, use a regular expression for
matching the rule's object class.
perms The permission(s) to match.
perms_equal If true, the permission set of the rule
must exactly match the permissions
criteria. If false, any set intersection
will match.
perms_regex If true, regular expression matching will be used
on the permission names instead of set logic.
role The name of the role to match in the
constraint expression.
role_indirect If true, members of an attribute will be
matched rather than the attribute itself.
role_regex If true, regular expression matching will
be used on the role.
type_ The name of the type/attribute to match in the
constraint expression.
type_indirect If true, members of an attribute will be
matched rather than the attribute itself.
type_regex If true, regular expression matching will
be used on the type/attribute.
user The name of the user to match in the
constraint expression.
user_regex If true, regular expression matching will
be used on the user.
"""
ruletype = CriteriaSetDescriptor(enum_class=ConstraintRuletype)
user = CriteriaDescriptor("user_regex", "lookup_user")
user_regex: bool = False
role = CriteriaDescriptor("role_regex", "lookup_role")
role_regex: bool = False
role_indirect: bool = True
type_ = CriteriaDescriptor("type_regex", "lookup_type_or_attr")
type_regex: bool = False
type_indirect: bool = True
def __init__(self, policy, **kwargs) -> None:
super(ConstraintQuery, self).__init__(policy, **kwargs)
self.log = logging.getLogger(__name__)
def _match_expr(self, expr, criteria, indirect, regex):
"""
Match roles/types/users in a constraint expression,
optionally by expanding the contents of attributes.
Parameters:
expr The expression to match.
criteria The criteria to match.
indirect If attributes in the expression should be expanded.
regex If regular expression matching should be used.
"""
if indirect:
obj = set()
for item in expr:
obj.update(item.expand())
else:
obj = expr
return match_in_set(obj, criteria, regex)
def results(self) -> Iterable[AnyConstraint]:
"""Generator which yields all matching constraints rules."""
self.log.info("Generating constraint results from {0.policy}".format(self))
self.log.debug("Ruletypes: {0.ruletype}".format(self))
self._match_object_class_debug(self.log)
self._match_perms_debug(self.log)
self.log.debug("User: {0.user!r}, regex: {0.user_regex}".format(self))
self.log.debug("Role: {0.role!r}, regex: {0.role_regex}".format(self))
self.log.debug("Type: {0.type_!r}, regex: {0.type_regex}".format(self))
for c in self.policy.constraints():
if self.ruletype:
if c.ruletype not in self.ruletype:
continue
if not self._match_object_class(c):
continue
try:
if not self._match_perms(c):
continue
except ConstraintUseError:
continue
if self.role and not self._match_expr(
c.expression.roles,
self.role,
self.role_indirect,
self.role_regex):
continue
if self.type_ and not self._match_expr(
c.expression.types,
self.type_,
self.type_indirect,
self.type_regex):
continue
if self.user and not self._match_expr(
c.expression.users,
self.user,
False,
self.user_regex):
continue
yield c
