# Copyright 2010 United States Government as represented by the # Administrator of the National Aeronautics and Space Administration. # All Rights Reserved. # Copyright (c) 2010 Citrix Systems, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. from eventlet import greenthread from lxml import etree from oslo_log import log as logging from oslo_utils import excutils from oslo_utils import importutils from oslo_utils import uuidutils import nova.conf import nova.virt.firewall as base_firewall from nova.virt import netutils LOG = logging.getLogger(__name__) CONF = nova.conf.CONF libvirt = None class NWFilterFirewall(base_firewall.FirewallDriver): """This class implements a network filtering mechanism by using libvirt's nwfilter. all instances get a filter ("nova-base") applied. This filter provides some basic security such as protection against MAC spoofing, IP spoofing, and ARP spoofing. """ def __init__(self, host, **kwargs): """Create an NWFilter firewall driver :param host: nova.virt.libvirt.host.Host instance :param kwargs: currently unused """ global libvirt if libvirt is None: try: libvirt = importutils.import_module('libvirt') except ImportError: LOG.warning("Libvirt module could not be loaded. " "NWFilterFirewall will not work correctly.") self._host = host self.static_filters_configured = False def apply_instance_filter(self, instance, network_info): """No-op. Everything is done in prepare_instance_filter.""" pass def _get_connection(self): return self._host.get_connection() _conn = property(_get_connection) def nova_no_nd_reflection_filter(self): """This filter protects false positives on IPv6 Duplicate Address Detection(DAD). """ uuid = self._get_filter_uuid('nova-no-nd-reflection') return ''' %s ''' % uuid def nova_dhcp_filter(self): """The standard allow-dhcp-server filter is an one, so it uses ebtables to allow traffic through. Without a corresponding rule in iptables, it'll get blocked anyway. """ uuid = self._get_filter_uuid('nova-allow-dhcp-server') return ''' %s ''' % uuid def setup_basic_filtering(self, instance, network_info): """Set up basic filtering (MAC, IP, and ARP spoofing protection).""" LOG.info('Called setup_basic_filtering in nwfilter', instance=instance) LOG.info('Ensuring static filters', instance=instance) self._ensure_static_filters() nodhcp_base_filter = self.get_base_filter_list(instance, False) dhcp_base_filter = self.get_base_filter_list(instance, True) for vif in network_info: _base_filter = nodhcp_base_filter for subnet in vif['network']['subnets']: if subnet.get_meta('dhcp_server'): _base_filter = dhcp_base_filter break self._define_filter(self._get_instance_filter_xml(instance, _base_filter, vif)) def _get_instance_filter_parameters(self, vif): parameters = [] def format_parameter(parameter, value): return ("" % (parameter, value)) network = vif['network'] if not vif['network'] or not vif['network']['subnets']: return parameters v4_subnets = [s for s in network['subnets'] if s['version'] == 4] v6_subnets = [s for s in network['subnets'] if s['version'] == 6] for subnet in v4_subnets: for ip in subnet['ips']: parameters.append(format_parameter('IP', ip['address'])) dhcp_server = subnet.get_meta('dhcp_server') if dhcp_server: parameters.append(format_parameter('DHCPSERVER', dhcp_server)) ipv4_cidr = subnet['cidr'] net, mask = netutils.get_net_and_mask(ipv4_cidr) parameters.append(format_parameter('PROJNET', net)) parameters.append(format_parameter('PROJMASK', mask)) for subnet in v6_subnets: gateway = subnet.get('gateway') if gateway: ra_server = gateway['address'] + "/128" parameters.append(format_parameter('RASERVER', ra_server)) ipv6_cidr = subnet['cidr'] net, prefix = netutils.get_net_and_prefixlen(ipv6_cidr) parameters.append(format_parameter('PROJNET6', net)) parameters.append(format_parameter('PROJMASK6', prefix)) return parameters def _get_instance_filter_xml(self, instance, filters, vif): nic_id = vif['address'].replace(':', '') instance_filter_name = self._instance_filter_name(instance, nic_id) parameters = self._get_instance_filter_parameters(vif) uuid = self._get_filter_uuid(instance_filter_name) xml = '''''' % instance_filter_name xml += '%s' % uuid for f in filters: xml += '''''' % f xml += ''.join(parameters) xml += '' xml += '' return xml def get_base_filter_list(self, instance, allow_dhcp): """Obtain a list of base filters to apply to an instance. The return value should be a list of strings, each specifying a filter name. Subclasses can override this function to add additional filters as needed. Additional filters added to the list must also be correctly defined within the subclass. """ if allow_dhcp: base_filter = 'nova-base' else: base_filter = 'nova-nodhcp' return [base_filter] def _ensure_static_filters(self): """Static filters are filters that have no need to be IP aware. There is no configuration or tuneability of these filters, so they can be set up once and forgotten about. """ if self.static_filters_configured: return filter_set = ['no-mac-spoofing', 'no-ip-spoofing', 'no-arp-spoofing'] self._define_filter(self.nova_no_nd_reflection_filter()) filter_set.append('nova-no-nd-reflection') self._define_filter(self._filter_container('nova-nodhcp', filter_set)) filter_set.append('allow-dhcp-server') self._define_filter(self._filter_container('nova-base', filter_set)) self._define_filter(self.nova_dhcp_filter()) self.static_filters_configured = True def _filter_container(self, name, filters): uuid = self._get_filter_uuid(name) xml = ''' %s %s ''' % (name, uuid, ''.join(["" % (f,) for f in filters])) return xml def _get_filter_uuid(self, name): try: flt = self._conn.nwfilterLookupByName(name) xml = flt.XMLDesc(0) doc = etree.fromstring(xml) u = doc.find("./uuid").text except Exception as e: LOG.debug(u"Cannot find UUID for filter '%(name)s': '%(e)s'", {'name': name, 'e': e}) u = uuidutils.generate_uuid(dashed=False) LOG.debug("UUID for filter '%s' is '%s'", name, u) return u def _define_filter(self, xml): if callable(xml): xml = xml() try: self._conn.nwfilterDefineXML(xml) except libvirt.libvirtError as ex: with excutils.save_and_reraise_exception() as ctxt: errcode = ex.get_error_code() if errcode == libvirt.VIR_ERR_OPERATION_FAILED: # Since libvirt 1.2.7 this operation can fail if the filter # with the same name already exists for the given uuid. # Unfortunately there is not a specific error code for this # so we have to parse the error message to see if that was # the failure. errmsg = ex.get_error_message() if 'already exists with uuid' in errmsg: ctxt.reraise = False def unfilter_instance(self, instance, network_info): """Clear out the nwfilter rules.""" for vif in network_info: nic_id = vif['address'].replace(':', '') instance_filter_name = self._instance_filter_name(instance, nic_id) # nwfilters may be defined in a separate thread in the case # of libvirt non-blocking mode, so we wait for completion max_retry = CONF.live_migration_retry_count for cnt in range(max_retry): try: _nw = self._conn.nwfilterLookupByName(instance_filter_name) _nw.undefine() break except libvirt.libvirtError as e: if cnt == max_retry - 1: raise errcode = e.get_error_code() if errcode == libvirt.VIR_ERR_OPERATION_INVALID: # This happens when the instance filter is still in use # (ie. when the instance has not terminated properly) LOG.info('Failed to undefine network filter ' '%(name)s. Try %(cnt)d of %(max_retry)d.', {'name': instance_filter_name, 'cnt': cnt + 1, 'max_retry': max_retry}, instance=instance) greenthread.sleep(1) else: LOG.debug('The nwfilter(%s) is not found.', instance_filter_name, instance=instance) break @staticmethod def _instance_filter_name(instance, nic_id=None): if not nic_id: return 'nova-instance-%s' % (instance.name) return 'nova-instance-%s-%s' % (instance.name, nic_id) def instance_filter_exists(self, instance, network_info): """Check nova-instance-instance-xxx exists.""" for vif in network_info: nic_id = vif['address'].replace(':', '') instance_filter_name = self._instance_filter_name(instance, nic_id) try: self._conn.nwfilterLookupByName(instance_filter_name) except libvirt.libvirtError: name = instance.name LOG.debug('The nwfilter(%(instance_filter_name)s) for' '%(name)s is not found.', {'instance_filter_name': instance_filter_name, 'name': name}, instance=instance) return False return True class IptablesFirewallDriver(base_firewall.IptablesFirewallDriver): def __init__(self, execute=None, **kwargs): """Create an IP tables firewall driver instance :param execute: unused, pass None :param kwargs: extra arguments The @kwargs parameter must contain a key 'host' that maps to an instance of the nova.virt.libvirt.host.Host class. """ super(IptablesFirewallDriver, self).__init__(**kwargs) self.nwfilter = NWFilterFirewall(kwargs['host']) def setup_basic_filtering(self, instance, network_info): """Set up basic NWFilter.""" self.nwfilter.setup_basic_filtering(instance, network_info) def apply_instance_filter(self, instance, network_info): """No-op. Everything is done in prepare_instance_filter.""" pass def unfilter_instance(self, instance, network_info): # NOTE(salvatore-orlando): # Overriding base class method for applying nwfilter operation if self.instance_info.pop(instance.id, None): self.remove_filters_for_instance(instance) self.iptables.apply() self.nwfilter.unfilter_instance(instance, network_info) else: LOG.info('Attempted to unfilter instance which is not filtered', instance=instance) def instance_filter_exists(self, instance, network_info): """Check nova-instance-instance-xxx exists.""" return self.nwfilter.instance_filter_exists(instance, network_info)