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# 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/>.
#
from socket import IPPROTO_TCP, IPPROTO_UDP, getprotobyname
from collections import namedtuple
from . import qpol
from . import symbol
from . import context
port_range = namedtuple("port_range", ["low", "high"])
# Python does not have a constant
# for the DCCP protocol.
IPPROTO_DCCP = getprotobyname("dccp")
def netifcon_factory(policy, name):
"""Factory function for creating netifcon objects."""
if not isinstance(name, qpol.qpol_netifcon_t):
raise NotImplementedError
return Netifcon(policy, name)
def nodecon_factory(policy, name):
"""Factory function for creating nodecon objects."""
if not isinstance(name, qpol.qpol_nodecon_t):
raise NotImplementedError
return Nodecon(policy, name)
def portcon_factory(policy, name):
"""Factory function for creating portcon objects."""
if not isinstance(name, qpol.qpol_portcon_t):
raise NotImplementedError
return Portcon(policy, name)
class NetContext(symbol.PolicySymbol):
"""Base class for in-policy network labeling rules."""
def __str__(self):
raise NotImplementedError
@property
def context(self):
"""The context for this statement."""
return context.context_factory(self.policy, self.qpol_symbol.context(self.policy))
def statement(self):
return str(self)
class Netifcon(NetContext):
"""A netifcon statement."""
def __str__(self):
return "netifcon {0.netif} {0.context} {0.packet}".format(self)
def __hash__(self):
return hash("netifcon|{0.netif}".format(self))
@property
def netif(self):
"""The network interface name."""
return self.qpol_symbol.name(self.policy)
@property
def context(self):
"""The context for the interface."""
return context.context_factory(self.policy, self.qpol_symbol.if_con(self.policy))
@property
def packet(self):
"""The context for the packets."""
return context.context_factory(self.policy, self.qpol_symbol.msg_con(self.policy))
class Nodecon(NetContext):
"""A nodecon statement."""
def __str__(self):
return "nodecon {0.address} {0.netmask} {0.context}".format(self)
def __hash__(self):
return hash("nodecon|{0.address}|{0.netmask}".format(self))
def __eq__(self, other):
# Libqpol allocates new C objects in the
# nodecons iterator, so pointer comparison
# in the PolicySymbol object doesn't work.
try:
return (self.address == other.address and
self.netmask == other.netmask and
self.context == other.context)
except AttributeError:
return (str(self) == str(other))
@property
def ip_version(self):
"""
The IP version for the nodecon (socket.AF_INET or
socket.AF_INET6).
"""
return self.qpol_symbol.protocol(self.policy)
@property
def address(self):
"""The network address for the nodecon."""
return self.qpol_symbol.addr(self.policy)
@property
def netmask(self):
"""The network mask for the nodecon."""
return self.qpol_symbol.mask(self.policy)
class PortconProtocol(int):
"""
A portcon protocol type.
The possible values are equivalent to protocol
values in the socket module, e.g. IPPROTO_TCP, but
overrides the string representation with the
corresponding protocol string (udp, tcp).
"""
_proto_to_text = {IPPROTO_DCCP: 'dccp',
IPPROTO_TCP: 'tcp',
IPPROTO_UDP: 'udp'}
def __new__(cls, value):
try:
# convert string representation
num = getprotobyname(value)
except TypeError:
num = value
if num not in cls._proto_to_text:
raise ValueError("{0} is not a supported IP protocol. "
"Values such as {1} (TCP) or {2} (UDP) should be used.".
format(value, IPPROTO_TCP, IPPROTO_UDP))
return super(PortconProtocol, cls).__new__(cls, num)
def __str__(self):
return self._proto_to_text[self]
class Portcon(NetContext):
"""A portcon statement."""
def __str__(self):
low, high = self.ports
if low == high:
return "portcon {0.protocol} {1} {0.context}".format(self, low)
else:
return "portcon {0.protocol} {1}-{2} {0.context}".format(self, low, high)
def __hash__(self):
return hash("portcon|{0.protocol}|{1.low}|{1.high}".format(self, self.ports))
@property
def protocol(self):
"""
The protocol number for the portcon (socket.IPPROTO_TCP
or socket.IPPROTO_UDP).
"""
return PortconProtocol(self.qpol_symbol.protocol(self.policy))
@property
def ports(self):
"""
The port range for this portcon.
Return: Tuple(low, high)
low The low port of the range.
high The high port of the range.
"""
low = self.qpol_symbol.low_port(self.policy)
high = self.qpol_symbol.high_port(self.policy)
return port_range(low, high)
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