# 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):
if symbol.is_extended(policy):
return AVRuleXperm(policy, symbol)
else:
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, (ExpandedAVRule, ExpandedAVRuleXperm, ExpandedTERule)):
return original
elif isinstance(original, AVRuleXperm):
rule = ExpandedAVRuleXperm(original.policy, original.qpol_symbol)
elif isinstance(original, AVRule):
rule = ExpandedAVRule(original.policy, original.qpol_symbol)
elif isinstance(original, TERule):
rule = ExpandedTERule(original.policy, original.qpol_symbol)
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",
"allowxperm", "auditallowxperm", "dontauditxperm", "neverallowxperm"]:
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:
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:
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)
# allow/dontaudit/auditallow/neverallow rules
perms = self.perms
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 ioctlSet(set):
"""
A set with overridden string functions which compresses
the output into ioctl ranges instead of individual elements.
"""
def __format__(self, spec):
"""
String formating.
The standard formatting (no specification) will render the
ranges of ioctls, space separated.
The , option by itself will render the ranges of ioctls,
comma separated
Any other combination of formatting options will fall back
to set's formatting behavior.
"""
# generate short permission notation
perms = sorted(self)
shortlist = []
for _, i in itertools.groupby(perms, key=lambda k, c=itertools.count(): k - next(c)):
group = list(i)
if len(group) > 1:
shortlist.append("{0:#06x}-{1:#06x}".format(group[0], group[-1]))
else:
shortlist.append("{0:#06x}".format(group[0]))
if not spec:
return " ".join(shortlist)
elif spec == ",":
return ", ".join(shortlist)
else:
return super(ioctlSet, self).__format__(spec)
def __str__(self):
return "{0}".format(self)
def __repr__(self):
return "{{ {0:,} }}".format(self)
def ranges(self):
"""
Return the number of ranges in the set. Main use
is to determine if brackets need to be used in
string output.
"""
return sum(1 for (_a, _b) in itertools.groupby(
sorted(self), key=lambda k, c=itertools.count(): k - next(c)))
class AVRuleXperm(AVRule):
"""An extended permission access vector type enforcement rule."""
extended = True
def __hash__(self):
return hash("{0.ruletype}|{0.source}|{0.target}|{0.tclass}|{0.xperm_type}".format(self))
def __str__(self):
try:
return self._rule_string
except AttributeError:
self._rule_string = "{0.ruletype} {0.source} {0.target}:{0.tclass} {0.xperm_type} ". \
format(self)
# generate short permission notation
perms = self.perms
if perms.ranges() > 1:
self._rule_string += "{{ {0} }};".format(perms)
else:
self._rule_string += "{0};".format(perms)
return self._rule_string
@property
def perms(self):
"""The rule's extended permission set."""
return ioctlSet(self.qpol_symbol.xperm_iter(self.policy))
@property
def xperm_type(self):
"""The standard permission extended by these permissions (e.g. ioctl)."""
return self.qpol_symbol.xperm_type(self.policy)
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 ExpandedAVRuleXperm(AVRuleXperm):
"""An expanded extended permission 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