488 lines
15 KiB
Python
488 lines
15 KiB
Python
# pylint: disable=too-few-public-methods
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#
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# The Qubes OS Project, https://www.qubes-os.org/
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#
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# Copyright (C) 2016
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# Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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#
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import datetime
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import subprocess
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import itertools
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import os
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import socket
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import lxml.etree
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import qubes
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import qubes.vm.qubesvm
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class RuleOption(object):
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def __init__(self, value):
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self._value = str(value)
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@property
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def rule(self):
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raise NotImplementedError
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def __str__(self):
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return self._value
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def __eq__(self, other):
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return str(self) == other
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# noinspection PyAbstractClass
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class RuleChoice(RuleOption):
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# pylint: disable=abstract-method
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def __init__(self, value):
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super(RuleChoice, self).__init__(value)
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self.allowed_values = \
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[v for k, v in self.__class__.__dict__.items()
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if not k.startswith('__') and isinstance(v, str) and
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not v.startswith('__')]
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if value not in self.allowed_values:
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raise ValueError(value)
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class Action(RuleChoice):
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accept = 'accept'
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drop = 'drop'
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@property
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def rule(self):
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return 'action=' + str(self)
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class Proto(RuleChoice):
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tcp = 'tcp'
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udp = 'udp'
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icmp = 'icmp'
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@property
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def rule(self):
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return 'proto=' + str(self)
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class DstHost(RuleOption):
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'''Represent host/network address: either IPv4, IPv6, or DNS name'''
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def __init__(self, value, prefixlen=None):
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# TODO: in python >= 3.3 ipaddress module could be used
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if value.count('/') > 1:
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raise ValueError('Too many /: ' + value)
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elif not value.count('/'):
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# add prefix length to bare IP addresses
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try:
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socket.inet_pton(socket.AF_INET6, value)
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self.prefixlen = prefixlen or 128
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if self.prefixlen < 0 or self.prefixlen > 128:
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raise ValueError(
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'netmask for IPv6 must be between 0 and 128')
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value += '/' + str(self.prefixlen)
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self.type = 'dst6'
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except socket.error:
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try:
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socket.inet_pton(socket.AF_INET, value)
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if value.count('.') != 3:
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raise ValueError(
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'Invalid number of dots in IPv4 address')
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self.prefixlen = prefixlen or 32
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if self.prefixlen < 0 or self.prefixlen > 32:
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raise ValueError(
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'netmask for IPv4 must be between 0 and 32')
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value += '/' + str(self.prefixlen)
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self.type = 'dst4'
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except socket.error:
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self.type = 'dsthost'
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self.prefixlen = 0
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else:
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host, prefixlen = value.split('/', 1)
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prefixlen = int(prefixlen)
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if prefixlen < 0:
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raise ValueError('netmask must be non-negative')
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self.prefixlen = prefixlen
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try:
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socket.inet_pton(socket.AF_INET6, host)
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if prefixlen > 128:
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raise ValueError('netmask for IPv6 must be <= 128')
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self.type = 'dst6'
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except socket.error:
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try:
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socket.inet_pton(socket.AF_INET, host)
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if prefixlen > 32:
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raise ValueError('netmask for IPv4 must be <= 32')
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self.type = 'dst4'
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if host.count('.') != 3:
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raise ValueError(
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'Invalid number of dots in IPv4 address')
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except socket.error:
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raise ValueError('Invalid IP address: ' + host)
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super(DstHost, self).__init__(value)
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@property
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def rule(self):
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return self.type + '=' + str(self)
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class DstPorts(RuleOption):
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def __init__(self, value):
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if isinstance(value, int):
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value = str(value)
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if value.count('-') == 1:
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self.range = [int(x) for x in value.split('-', 1)]
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elif not value.count('-'):
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self.range = [int(value), int(value)]
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else:
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raise ValueError(value)
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if any(port < 0 or port > 65536 for port in self.range):
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raise ValueError('Ports out of range')
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if self.range[0] > self.range[1]:
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raise ValueError('Invalid port range')
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super(DstPorts, self).__init__(
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str(self.range[0]) if self.range[0] == self.range[1]
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else '-'.join(map(str, self.range)))
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@property
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def rule(self):
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return 'dstports=' + '{!s}-{!s}'.format(*self.range)
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class IcmpType(RuleOption):
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def __init__(self, value):
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super(IcmpType, self).__init__(value)
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value = int(value)
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if value < 0 or value > 255:
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raise ValueError('ICMP type out of range')
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@property
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def rule(self):
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return 'icmptype=' + str(self)
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class SpecialTarget(RuleChoice):
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dns = 'dns'
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@property
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def rule(self):
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return 'specialtarget=' + str(self)
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class Expire(RuleOption):
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def __init__(self, value):
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super(Expire, self).__init__(value)
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self.datetime = datetime.datetime.utcfromtimestamp(int(value))
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@property
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def rule(self):
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return None
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@property
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def expired(self):
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return self.datetime < datetime.datetime.utcnow()
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class Comment(RuleOption):
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@property
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def rule(self):
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return None
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class Rule(qubes.PropertyHolder):
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def __init__(self, xml=None, **kwargs):
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'''Single firewall rule
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:param xml: XML element describing rule, or None
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:param kwargs: rule elements
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'''
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super(Rule, self).__init__(xml, **kwargs)
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self.load_properties()
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self.events_enabled = True
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# validate dependencies
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if self.dstports:
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self.on_set_dstports('property-set:dstports', 'dstports',
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self.dstports, None)
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if self.icmptype:
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self.on_set_icmptype('property-set:icmptype', 'icmptype',
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self.icmptype, None)
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self.property_require('action', False, True)
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action = qubes.property('action',
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type=Action,
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order=0,
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doc='rule action')
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proto = qubes.property('proto',
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type=Proto,
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default=None,
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order=1,
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doc='protocol to match')
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dsthost = qubes.property('dsthost',
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type=DstHost,
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default=None,
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order=1,
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doc='destination host/network')
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dstports = qubes.property('dstports',
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type=DstPorts,
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default=None,
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order=2,
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doc='Destination port(s) (for \'tcp\' and \'udp\' protocol only)')
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icmptype = qubes.property('icmptype',
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type=IcmpType,
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default=None,
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order=2,
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doc='ICMP packet type (for \'icmp\' protocol only)')
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specialtarget = qubes.property('specialtarget',
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type=SpecialTarget,
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default=None,
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order=1,
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doc='Special target, for now only \'dns\' supported')
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expire = qubes.property('expire',
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type=Expire,
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default=None,
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doc='Timestamp (UNIX epoch) on which this rule expire')
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comment = qubes.property('comment',
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type=Comment,
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default=None,
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doc='User comment')
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# noinspection PyUnusedLocal
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@qubes.events.handler('property-pre-set:dstports')
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def on_set_dstports(self, _event, _prop, _new_value, _old_value=None):
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if self.proto not in ('tcp', 'udp'):
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raise ValueError(
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'dstports valid only for \'tcp\' and \'udp\' protocols')
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# noinspection PyUnusedLocal
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@qubes.events.handler('property-pre-set:icmptype')
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def on_set_icmptype(self, _event, _prop, _new_value, _old_value=None):
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if self.proto not in ('icmp',):
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raise ValueError('icmptype valid only for \'icmp\' protocol')
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# noinspection PyUnusedLocal
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@qubes.events.handler('property-set:proto')
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def on_set_proto(self, _event, _prop, new_value, _old_value=None):
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if new_value not in ('tcp', 'udp'):
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self.dstports = qubes.property.DEFAULT
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if new_value not in ('icmp',):
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self.icmptype = qubes.property.DEFAULT
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@qubes.events.handler('property-del:proto')
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def on_del_proto(self, _event, _prop, _old_value):
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self.dstports = qubes.property.DEFAULT
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self.icmptype = qubes.property.DEFAULT
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@property
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def rule(self):
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if self.expire and self.expire.expired:
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return None
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values = []
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for prop in self.property_list():
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value = getattr(self, prop.__name__)
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if value is None:
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continue
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if value.rule is None:
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continue
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values.append(value.rule)
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return ' '.join(values)
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@classmethod
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def from_xml_v1(cls, node, action):
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netmask = node.get('netmask')
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if netmask is None:
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netmask = 32
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else:
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netmask = int(netmask)
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address = node.get('address')
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if address:
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dsthost = DstHost(address, netmask)
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else:
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dsthost = None
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proto = node.get('proto')
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port = node.get('port')
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toport = node.get('toport')
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if port and toport:
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dstports = port + '-' + toport
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elif port:
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dstports = port
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else:
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dstports = None
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# backward compatibility: protocol defaults to TCP if port is specified
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if dstports and not proto:
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proto = 'tcp'
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if proto == 'any':
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proto = None
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expire = node.get('expire')
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kwargs = {
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'action': action,
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}
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if dsthost:
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kwargs['dsthost'] = dsthost
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if dstports:
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kwargs['dstports'] = dstports
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if proto:
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kwargs['proto'] = proto
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if expire:
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kwargs['expire'] = expire
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return cls(**kwargs)
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def __eq__(self, other):
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return self.rule == other.rule
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class Firewall(object):
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def __init__(self, vm, load=True):
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assert hasattr(vm, 'firewall_conf')
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self.vm = vm
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#: firewall rules
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self.rules = []
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#: default action
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self.policy = None
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if load:
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self.load()
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def load_defaults(self):
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self.rules = []
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self.policy = Action('accept')
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def load(self):
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firewall_conf = os.path.join(self.vm.dir_path, self.vm.firewall_conf)
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if os.path.exists(firewall_conf):
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self.rules = []
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tree = lxml.etree.parse(firewall_conf)
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root = tree.getroot()
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version = root.get('version', '1')
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if version == '1':
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self.load_v1(root)
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elif version == '2':
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self.load_v2(root)
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else:
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raise qubes.exc.QubesVMError(self.vm,
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'Unsupported firewall.xml version: {}'.format(version))
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else:
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self.load_defaults()
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def load_v1(self, xml_root):
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policy_v1 = xml_root.get('policy')
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assert policy_v1 in ('allow', 'deny')
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if policy_v1 == 'allow':
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self.policy = Action('accept')
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else:
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self.policy = Action('drop')
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def _translate_action(key):
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if xml_root.get(key, policy_v1) == 'allow':
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return Action.accept
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else:
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return Action.drop
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self.rules.append(Rule(None,
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action=_translate_action('dns'),
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specialtarget=SpecialTarget('dns')))
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self.rules.append(Rule(None,
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action=_translate_action('icmp'),
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proto=Proto.icmp))
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if self.policy == Action.accept:
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rule_action = Action.drop
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else:
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rule_action = Action.accept
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for element in xml_root:
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rule = Rule.from_xml_v1(element, rule_action)
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self.rules.append(rule)
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def load_v2(self, xml_root):
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self.policy = Action(xml_root.findtext('policy'))
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xml_rules = xml_root.find('rules')
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for xml_rule in xml_rules:
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rule = Rule(xml_rule)
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self.rules.append(rule)
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def save(self):
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firewall_conf = os.path.join(self.vm.dir_path, self.vm.firewall_conf)
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expiring_rules_present = False
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xml_root = lxml.etree.Element('firewall', version=str(2))
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xml_policy = lxml.etree.Element('policy')
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xml_policy.text = str(self.policy)
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xml_root.append(xml_policy)
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xml_rules = lxml.etree.Element('rules')
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for rule in self.rules:
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if rule.expire:
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if rule.expire and rule.expire.expired:
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continue
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else:
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expiring_rules_present = True
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xml_rule = lxml.etree.Element('rule')
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xml_rule.append(rule.xml_properties())
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xml_rules.append(xml_rule)
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xml_root.append(xml_rules)
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xml_tree = lxml.etree.ElementTree(xml_root)
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try:
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old_umask = os.umask(0o002)
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with open(firewall_conf, 'wb') as firewall_xml:
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xml_tree.write(firewall_xml, encoding="UTF-8",
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pretty_print=True)
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os.umask(old_umask)
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except EnvironmentError as err:
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self.vm.log.error("save error: {}".format(err))
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raise qubes.exc.QubesException('save error: {}'.format(err))
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self.vm.fire_event('firewall-changed')
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if expiring_rules_present and not self.vm.app.vmm.offline_mode:
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subprocess.call(["sudo", "systemctl", "start",
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"qubes-reload-firewall@%s.timer" % self.vm.name])
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def qdb_entries(self, addr_family=None):
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entries = {
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'policy': str(self.policy)
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}
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exclude_dsttype = None
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if addr_family is not None:
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exclude_dsttype = 'dst4' if addr_family == 6 else 'dst6'
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for ruleno, rule in zip(itertools.count(), self.rules):
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# exclude rules for another address family
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if rule.dsthost and rule.dsthost.type == exclude_dsttype:
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continue
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entries['{:04}'.format(ruleno)] = rule.rule
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return entries
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