# 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 boolcond
def te_rule_factory(policy, symbol):
"""Factory function for creating TE rule objects."""
if isinstance(symbol, qpol.qpol_avrule_t):
return AVRule(policy, symbol)
elif isinstance(symbol, (qpol.qpol_terule_t, qpol.qpol_filename_trans_t)):
return TERule(policy, symbol)
else:
raise TypeError("TE rules cannot be looked-up.")
def expanded_te_rule_factory(original, source, target):
"""
Factory function for creating expanded TE rules.
original The TE 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, AVRule):
rule = ExpandedAVRule(original.policy, original.qpol_symbol)
elif isinstance(original, TERule):
rule = ExpandedTERule(original.policy, original.qpol_symbol)
elif isinstance(original, (ExpandedAVRule, ExpandedTERule)):
return original
else:
raise TypeError("The original rule must be a TE rule class.")
rule.source = source
rule.target = target
rule.origin = original
return rule
def validate_ruletype(t):
"""Validate TE Rule types."""
if t not in ["allow", "auditallow", "dontaudit", "neverallow",
"type_transition", "type_member", "type_change"]:
raise exception.InvalidTERuleType("{0} is not a valid TE rule type.".format(t))
return t
class BaseTERule(rule.PolicyRule):
"""A type enforcement rule."""
@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 filename(self):
raise NotImplementedError
@property
def conditional(self):
"""The rule's conditional expression."""
try:
return boolcond.condexpr_factory(self.policy, self.qpol_symbol.cond(self.policy))
except (AttributeError, ValueError):
# AttributeError: name filetrans rules cannot be conditional
# so no member function
# ValueError: The rule is not conditional
raise exception.RuleNotConditional
@property
def conditional_block(self):
"""The conditional block of the rule (T/F)"""
try:
return bool(self.qpol_symbol.which_list(self.policy))
except (AttributeError, ValueError):
# AttributeError: name filetrans rules cannot be conditional
# so no member function
# ValueError: The rule is not conditional
raise exception.RuleNotConditional
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_te_rule_factory(self, s, t)
class AVRule(BaseTERule):
"""An access vector type enforcement rule."""
def __str__(self):
try:
return self._rule_string
except AttributeError:
self._rule_string = "{0.ruletype} {0.source} {0.target}:{0.tclass} ".format(self)
perms = self.perms
# allow/dontaudit/auditallow/neverallow rules
if len(perms) > 1:
self._rule_string += "{{ {0} }};".format(' '.join(perms))
else:
# convert to list since sets cannot be indexed
self._rule_string += "{0};".format(list(perms)[0])
try:
self._rule_string += " [ {0.conditional} ]:{0.conditional_block}".format(self)
except exception.RuleNotConditional:
pass
return self._rule_string
@property
def perms(self):
"""The rule's permission set."""
return set(self.qpol_symbol.perm_iter(self.policy))
@property
def default(self):
"""The rule's default type."""
raise exception.RuleUseError("{0} rules do not have a default type.".format(self.ruletype))
@property
def filename(self):
raise exception.RuleUseError("{0} rules do not have file names".format(self.ruletype))
class TERule(BaseTERule):
"""A type_* type enforcement rule."""
def __str__(self):
try:
return self._rule_string
except AttributeError:
self._rule_string = "{0.ruletype} {0.source} {0.target}:{0.tclass} {0.default}".format(
self)
try:
self._rule_string += " \"{0}\";".format(self.filename)
except (exception.TERuleNoFilename, exception.RuleUseError):
# invalid use for type_change/member
self._rule_string += ";"
try:
self._rule_string += " [ {0.conditional} ]:{0.conditional_block}".format(self)
except exception.RuleNotConditional:
pass
return self._rule_string
def __hash__(self):
try:
cond = self.conditional
cond_block = self.conditional_block
except exception.RuleNotConditional:
cond = None
cond_block = None
try:
filename = self.filename
except (exception.TERuleNoFilename, exception.RuleUseError):
filename = None
return hash("{0.ruletype}|{0.source}|{0.target}|{0.tclass}|{1}|{2}|{3}".format(
self, filename, cond, cond_block))
@property
def perms(self):
"""The rule's permission set."""
raise exception.RuleUseError(
"{0} rules do not have a permission set.".format(self.ruletype))
@property
def default(self):
"""The rule's default type."""
return typeattr.type_factory(self.policy, self.qpol_symbol.default_type(self.policy))
@property
def filename(self):
"""The type_transition rule's file name."""
try:
return self.qpol_symbol.filename(self.policy)
except AttributeError:
if self.ruletype == "type_transition":
raise exception.TERuleNoFilename
else:
raise exception.RuleUseError("{0} rules do not have file names".
format(self.ruletype))
class ExpandedAVRule(AVRule):
"""An expanded access vector type enforcement rule."""
source = None
target = None
origin = None
class ExpandedTERule(TERule):
"""An expanded type_* type enforcement rule."""
source = None
target = None
origin = None