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# Copyright 2014, 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 . 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 validate_ruletype(types):
"""Validate TE Rule types."""
for t in 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))
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
class AVRule(BaseTERule):
"""An access vector type enforcement rule."""
def __str__(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:
rule_string += "{{ {0} }};".format(' '.join(perms))
else:
# convert to list since sets cannot be indexed
rule_string += "{0};".format(list(perms)[0])
try:
rule_string += " [ {0} ]".format(self.conditional)
except exception.RuleNotConditional:
pass
return 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):
rule_string = "{0.ruletype} {0.source} {0.target}:{0.tclass} {0.default}".format(self)
try:
rule_string += " \"{0}\";".format(self.filename)
except (exception.TERuleNoFilename, exception.RuleUseError):
# invalid use for type_change/member
rule_string += ";"
try:
rule_string += " [ {0} ]".format(self.conditional)
except exception.RuleNotConditional:
pass
return rule_string
@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))
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