From bf28c724ddbe8f7e67f91513da5f302d5372314d Mon Sep 17 00:00:00 2001 From: Kevin Benton Date: Mon, 29 Jun 2015 21:05:08 -0700 Subject: [PATCH] Add ARP spoofing protection for LinuxBridge agent This patch adds ARP spoofing protection for the Linux Bridge agent based on ebtables. This code was written to be minimally invasive with the intent of back-porting to Kilo. The protection is enabled and disabled with the same 'prevent_arp_spoofing' agent config flag added for the OVS agent in I7c079b779245a0af6bc793564fa8a560e4226afe. The protection works by setting up an ebtables chain for each port and jumping all ARP traffic to that chain. The port-specific chains have a default DROP policy and then have allow rules installed that only allow ARP traffic with a source CIDR that matches one of the port's fixed IPs or an allowed address pair. Since this is a back-port to Kilo, it is disabled by default just like the protection added for OVS. This patch additionally pulls back the required ebtables filter and the functional test helpers to support the tests. Conflicts: neutron/plugins/linuxbridge/agent/linuxbridge_neutron_agent.py neutron/plugins/linuxbridge/common/config.py neutron/tests/common/machine_fixtures.py Closes-Bug: #1274034 Change-Id: I0b0e3b1272472385dff060897ecbd25e93fd78e7 (cherry picked from commit 04197bc4bbf2bc611371060db839028c2686f87a) --- etc/neutron/rootwrap.d/ebtables.filters | 11 ++ .../plugins/linuxbridge/agent/arp_protect.py | 128 ++++++++++++++++++ .../agent/linuxbridge_neutron_agent.py | 13 ++ neutron/plugins/linuxbridge/common/config.py | 16 +++ neutron/plugins/openvswitch/common/config.py | 5 +- neutron/tests/common/machine_fixtures.py | 96 +++++++++++++ neutron/tests/common/net_helpers.py | 45 ++++++ .../linux/test_linuxbridge_arp_protect.py | 100 ++++++++++++++ 8 files changed, 412 insertions(+), 2 deletions(-) create mode 100644 etc/neutron/rootwrap.d/ebtables.filters create mode 100644 neutron/plugins/linuxbridge/agent/arp_protect.py create mode 100644 neutron/tests/common/machine_fixtures.py create mode 100644 neutron/tests/functional/agent/linux/test_linuxbridge_arp_protect.py diff --git a/etc/neutron/rootwrap.d/ebtables.filters b/etc/neutron/rootwrap.d/ebtables.filters new file mode 100644 index 00000000000..8e810e7b551 --- /dev/null +++ b/etc/neutron/rootwrap.d/ebtables.filters @@ -0,0 +1,11 @@ +# neutron-rootwrap command filters for nodes on which neutron is +# expected to control network +# +# This file should be owned by (and only-writeable by) the root user + +# format seems to be +# cmd-name: filter-name, raw-command, user, args + +[Filters] + +ebtables: CommandFilter, ebtables, root diff --git a/neutron/plugins/linuxbridge/agent/arp_protect.py b/neutron/plugins/linuxbridge/agent/arp_protect.py new file mode 100644 index 00000000000..10fcae52a63 --- /dev/null +++ b/neutron/plugins/linuxbridge/agent/arp_protect.py @@ -0,0 +1,128 @@ +# Copyright (c) 2015 Mirantis, Inc. +# All Rights Reserved. +# +# 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. + +import netaddr +from oslo_concurrency import lockutils +from oslo_log import log as logging + +from neutron.agent.linux import ip_lib +from neutron.i18n import _LI + +LOG = logging.getLogger(__name__) +SPOOF_CHAIN_PREFIX = 'neutronARP-' + + +def setup_arp_spoofing_protection(vif, port_details): + current_rules = ebtables(['-L']).splitlines() + if not port_details.get('port_security_enabled', True): + # clear any previous entries related to this port + delete_arp_spoofing_protection([vif], current_rules) + LOG.info(_LI("Skipping ARP spoofing rules for port '%s' because " + "it has port security disabled"), vif) + return + # collect all of the addresses and cidrs that belong to the port + addresses = {f['ip_address'] for f in port_details['fixed_ips']} + if port_details.get('allowed_address_pairs'): + addresses |= {p['ip_address'] + for p in port_details['allowed_address_pairs']} + + addresses = {ip for ip in addresses + if netaddr.IPNetwork(ip).version == 4} + if any(netaddr.IPNetwork(ip).prefixlen == 0 for ip in addresses): + # don't try to install protection because a /0 prefix allows any + # address anyway and the ARP_SPA can only match on /1 or more. + return + + install_arp_spoofing_protection(vif, addresses, current_rules) + + +def chain_name(vif): + # start each chain with a common identifer for cleanup to find + return '%s%s' % (SPOOF_CHAIN_PREFIX, vif) + + +@lockutils.synchronized('ebtables') +def delete_arp_spoofing_protection(vifs, current_rules=None): + if not current_rules: + current_rules = ebtables(['-L']).splitlines() + # delete the jump rule and then delete the whole chain + jumps = [vif for vif in vifs if vif_jump_present(vif, current_rules)] + for vif in jumps: + ebtables(['-D', 'FORWARD', '-i', vif, '-j', + chain_name(vif), '-p', 'ARP']) + for vif in vifs: + if chain_exists(chain_name(vif), current_rules): + ebtables(['-X', chain_name(vif)]) + + +def delete_unreferenced_arp_protection(current_vifs): + # deletes all jump rules and chains that aren't in current_vifs but match + # the spoof prefix + output = ebtables(['-L']).splitlines() + to_delete = [] + for line in output: + # we're looking to find and turn the following: + # Bridge chain: SPOOF_CHAIN_PREFIXtap199, entries: 0, policy: DROP + # into 'tap199' + if line.startswith('Bridge chain: %s' % SPOOF_CHAIN_PREFIX): + devname = line.split(SPOOF_CHAIN_PREFIX, 1)[1].split(',')[0] + if devname not in current_vifs: + to_delete.append(devname) + LOG.info(_LI("Clearing orphaned ARP spoofing entries for devices %s"), + to_delete) + delete_arp_spoofing_protection(to_delete, output) + + +@lockutils.synchronized('ebtables') +def install_arp_spoofing_protection(vif, addresses, current_rules): + # make a VIF-specific ARP chain so we don't conflict with other rules + vif_chain = chain_name(vif) + if not chain_exists(vif_chain, current_rules): + ebtables(['-N', vif_chain, '-P', 'DROP']) + # flush the chain to clear previous accepts. this will cause dropped ARP + # packets until the allows are installed, but that's better than leaked + # spoofed packets and ARP can handle losses. + ebtables(['-F', vif_chain]) + for addr in addresses: + ebtables(['-A', vif_chain, '-p', 'ARP', '--arp-ip-src', addr, + '-j', 'ACCEPT']) + # check if jump rule already exists, if not, install it + if not vif_jump_present(vif, current_rules): + ebtables(['-A', 'FORWARD', '-i', vif, '-j', + vif_chain, '-p', 'ARP']) + + +def chain_exists(chain, current_rules): + for rule in current_rules: + if rule.startswith('Bridge chain: %s' % chain): + return True + return False + + +def vif_jump_present(vif, current_rules): + searches = (('-i %s' % vif), ('-j %s' % chain_name(vif)), ('-p ARP')) + for line in current_rules: + if all(s in line for s in searches): + return True + return False + + +# Used to scope ebtables commands in testing +NAMESPACE = None + + +def ebtables(comm): + execute = ip_lib.IPWrapper(NAMESPACE).netns.execute + return execute(['ebtables'] + comm, run_as_root=True) diff --git a/neutron/plugins/linuxbridge/agent/linuxbridge_neutron_agent.py b/neutron/plugins/linuxbridge/agent/linuxbridge_neutron_agent.py index db9eff1899c..e8be12b1a57 100644 --- a/neutron/plugins/linuxbridge/agent/linuxbridge_neutron_agent.py +++ b/neutron/plugins/linuxbridge/agent/linuxbridge_neutron_agent.py @@ -45,6 +45,7 @@ from neutron import context from neutron.i18n import _LE, _LI, _LW from neutron.openstack.common import loopingcall from neutron.plugins.common import constants as p_const +from neutron.plugins.linuxbridge.agent import arp_protect from neutron.plugins.linuxbridge.common import config # noqa from neutron.plugins.linuxbridge.common import constants as lconst @@ -753,6 +754,7 @@ class LinuxBridgeNeutronAgentRPC(object): def __init__(self, interface_mappings, polling_interval): self.polling_interval = polling_interval + self.prevent_arp_spoofing = cfg.CONF.AGENT.prevent_arp_spoofing self.setup_linux_bridge(interface_mappings) configurations = {'interface_mappings': interface_mappings} if self.br_mgr.vxlan_mode != lconst.VXLAN_NONE: @@ -870,6 +872,11 @@ class LinuxBridgeNeutronAgentRPC(object): if 'port_id' in device_details: LOG.info(_LI("Port %(device)s updated. Details: %(details)s"), {'device': device, 'details': device_details}) + if self.prevent_arp_spoofing: + port = self.br_mgr.get_tap_device_name( + device_details['port_id']) + arp_protect.setup_arp_spoofing_protection(port, + device_details) if device_details['admin_state_up']: # create the networking for the port network_type = device_details.get('network_type') @@ -923,6 +930,8 @@ class LinuxBridgeNeutronAgentRPC(object): LOG.info(_LI("Port %s updated."), device) else: LOG.debug("Device %s not defined on plugin", device) + if self.prevent_arp_spoofing: + arp_protect.delete_arp_spoofing_protection(devices) return resync def scan_devices(self, previous, sync): @@ -943,6 +952,10 @@ class LinuxBridgeNeutronAgentRPC(object): 'current': set(), 'updated': set(), 'removed': set()} + # clear any orphaned ARP spoofing rules (e.g. interface was + # manually deleted) + if self.prevent_arp_spoofing: + arp_protect.delete_unreferenced_arp_protection(current_devices) if sync: # This is the first iteration, or the previous one had a problem. diff --git a/neutron/plugins/linuxbridge/common/config.py b/neutron/plugins/linuxbridge/common/config.py index 90c6548dc83..88ba9b6d5e3 100644 --- a/neutron/plugins/linuxbridge/common/config.py +++ b/neutron/plugins/linuxbridge/common/config.py @@ -62,6 +62,22 @@ agent_opts = [ "polling for local device changes.")), cfg.BoolOpt('rpc_support_old_agents', default=False, help=_("Enable server RPC compatibility with old agents")), + # TODO(kevinbenton): The following opt is duplicated between the OVS agent + # and the Linuxbridge agent to make it easy to back-port. These shared opts + # should be moved into a common agent config options location as part of + # the deduplication work. + cfg.BoolOpt('prevent_arp_spoofing', default=False, + help=_("Enable suppression of ARP responses that don't match " + "an IP address that belongs to the port from which " + "they originate. Note: This prevents the VMs attached " + "to this agent from spoofing, it doesn't protect them " + "from other devices which have the capability to spoof " + "(e.g. bare metal or VMs attached to agents without " + "this flag set to True). Spoofing rules will not be " + "added to any ports that have port security disabled. " + "For LinuxBridge, this requires ebtables. For OVS, it " + "requires a version that supports matching ARP " + "headers.")) ] diff --git a/neutron/plugins/openvswitch/common/config.py b/neutron/plugins/openvswitch/common/config.py index a26178f5093..8046a2433e8 100644 --- a/neutron/plugins/openvswitch/common/config.py +++ b/neutron/plugins/openvswitch/common/config.py @@ -83,8 +83,9 @@ agent_opts = [ "(e.g. bare metal or VMs attached to agents without " "this flag set to True). Spoofing rules will not be " "added to any ports that have port security disabled. " - "This requires a version of OVS that supports matching " - "ARP headers.")), + "For LinuxBridge, this requires ebtables. For OVS, it " + "requires a version that supports matching ARP " + "headers.")), cfg.BoolOpt('dont_fragment', default=True, help=_("Set or un-set the don't fragment (DF) bit on " "outgoing IP packet carrying GRE/VXLAN tunnel.")), diff --git a/neutron/tests/common/machine_fixtures.py b/neutron/tests/common/machine_fixtures.py new file mode 100644 index 00000000000..864cad46be7 --- /dev/null +++ b/neutron/tests/common/machine_fixtures.py @@ -0,0 +1,96 @@ +# Copyright (c) 2015 Thales Services SAS +# +# 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. +# + +import fixtures + +from neutron.agent.linux import ip_lib +from neutron.tests.common import net_helpers + + +class FakeMachine(fixtures.Fixture): + """Create a fake machine. + + :ivar bridge: bridge on which the fake machine is bound + :ivar ip_cidr: fake machine ip_cidr + :type ip_cidr: str + :ivar ip: fake machine ip + :type ip: str + :ivar gateway_ip: fake machine gateway ip + :type gateway_ip: str + + :ivar namespace: namespace emulating the machine + :type namespace: str + :ivar port: port binding the namespace to the bridge + :type port: IPDevice + """ + + def __init__(self, bridge, ip_cidr, gateway_ip=None): + super(FakeMachine, self).__init__() + self.bridge = bridge + self.ip_cidr = ip_cidr + self.ip = self.ip_cidr.partition('/')[0] + self.gateway_ip = gateway_ip + + def setUp(self): + super(FakeMachine, self).setUp() + ns_fixture = self.useFixture( + net_helpers.NamespaceFixture()) + self.namespace = ns_fixture.name + + self.port = self.useFixture( + net_helpers.PortFixture.get(self.bridge, self.namespace)).port + self.port.addr.add(self.ip_cidr) + + if self.gateway_ip: + net_helpers.set_namespace_gateway(self.port, self.gateway_ip) + + def execute(self, *args, **kwargs): + ns_ip_wrapper = ip_lib.IPWrapper(self.namespace) + return ns_ip_wrapper.netns.execute(*args, **kwargs) + + def assert_ping(self, dst_ip): + net_helpers.assert_ping(self.namespace, dst_ip) + + def assert_no_ping(self, dst_ip): + net_helpers.assert_no_ping(self.namespace, dst_ip) + + +class PeerMachines(fixtures.Fixture): + """Create 'amount' peered machines on an ip_cidr. + + :ivar bridge: bridge on which peer machines are bound + :ivar ip_cidr: ip_cidr on which peer machines have ips + :type ip_cidr: str + :ivar machines: fake machines + :type machines: FakeMachine list + """ + + CIDR = '192.168.0.1/24' + + def __init__(self, bridge, ip_cidr=None, gateway_ip=None, amount=2): + super(PeerMachines, self).__init__() + self.bridge = bridge + self.ip_cidr = ip_cidr or self.CIDR + self.gateway_ip = gateway_ip + self.amount = amount + + def setUp(self): + super(PeerMachines, self).setUp() + self.machines = [] + for index in range(self.amount): + ip_cidr = net_helpers.increment_ip_cidr(self.ip_cidr, index) + self.machines.append( + self.useFixture( + FakeMachine(self.bridge, ip_cidr, self.gateway_ip))) diff --git a/neutron/tests/common/net_helpers.py b/neutron/tests/common/net_helpers.py index 85a9a8b0362..07d9ac88987 100644 --- a/neutron/tests/common/net_helpers.py +++ b/neutron/tests/common/net_helpers.py @@ -62,6 +62,31 @@ def set_namespace_gateway(port_dev, gateway_ip): port_dev.route.add_gateway(gateway_ip) +def assert_arping(src_namespace, dst_ip, source=None, timeout=1, count=1): + """Send arp request using arping executable. + + NOTE: ARP protocol is used in IPv4 only. IPv6 uses Neighbour Discovery + Protocol instead. + """ + ns_ip_wrapper = ip_lib.IPWrapper(src_namespace) + arping_cmd = ['arping', '-c', count, '-w', timeout] + if source: + arping_cmd.extend(['-s', source]) + arping_cmd.append(dst_ip) + ns_ip_wrapper.netns.execute(arping_cmd) + + +def assert_no_arping(src_namespace, dst_ip, source=None, timeout=1, count=1): + try: + assert_arping(src_namespace, dst_ip, source, timeout, count) + except RuntimeError: + pass + else: + tools.fail("destination ip %(destination)s is replying to arp from " + "namespace %(ns)s, but it shouldn't" % + {'ns': src_namespace, 'destination': dst_ip}) + + class NamespaceFixture(fixtures.Fixture): """Create a namespace. @@ -116,6 +141,15 @@ class VethFixture(fixtures.Fixture): # when a namespace owning a veth endpoint is deleted. pass + @staticmethod + def get_peer_name(name): + if name.startswith(VETH0_PREFIX): + return name.replace(VETH0_PREFIX, VETH1_PREFIX) + elif name.startswith(VETH1_PREFIX): + return name.replace(VETH1_PREFIX, VETH0_PREFIX) + else: + tools.fail('%s is not a valid VethFixture veth endpoint' % name) + @six.add_metaclass(abc.ABCMeta) class PortFixture(fixtures.Fixture): @@ -140,6 +174,17 @@ class PortFixture(fixtures.Fixture): if not self.bridge: self.bridge = self.useFixture(self._create_bridge_fixture()).bridge + @classmethod + def get(cls, bridge, namespace=None): + """Deduce PortFixture class from bridge type and instantiate it.""" + if isinstance(bridge, ovs_lib.OVSBridge): + return OVSPortFixture(bridge, namespace) + if isinstance(bridge, bridge_lib.BridgeDevice): + return LinuxBridgePortFixture(bridge, namespace) + if isinstance(bridge, VethBridge): + return VethPortFixture(bridge, namespace) + tools.fail('Unexpected bridge type: %s' % type(bridge)) + class OVSBridgeFixture(fixtures.Fixture): """Create an OVS bridge. diff --git a/neutron/tests/functional/agent/linux/test_linuxbridge_arp_protect.py b/neutron/tests/functional/agent/linux/test_linuxbridge_arp_protect.py new file mode 100644 index 00000000000..be7a9cd57ea --- /dev/null +++ b/neutron/tests/functional/agent/linux/test_linuxbridge_arp_protect.py @@ -0,0 +1,100 @@ +# Copyright (c) 2015 Mirantis, Inc. +# All Rights Reserved. +# +# 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 oslo_config import cfg + +from neutron.plugins.linuxbridge.agent import arp_protect +from neutron.tests.common import machine_fixtures +from neutron.tests.common import net_helpers +from neutron.tests.functional import base as functional_base + +no_arping = net_helpers.assert_no_arping +arping = net_helpers.assert_arping + + +class LinuxBridgeARPSpoofTestCase(functional_base.BaseSudoTestCase): + + def setUp(self): + super(LinuxBridgeARPSpoofTestCase, self).setUp() + cfg.CONF.set_override('prevent_arp_spoofing', True, 'AGENT') + lbfixture = self.useFixture(net_helpers.LinuxBridgeFixture()) + self.addCleanup(setattr, arp_protect, 'NAMESPACE', None) + arp_protect.NAMESPACE = lbfixture.namespace + bridge = lbfixture.bridge + self.source, self.destination, self.observer = self.useFixture( + machine_fixtures.PeerMachines(bridge, amount=3)).machines + + def _add_arp_protection(self, machine, addresses, extra_port_dict=None): + port_dict = {'fixed_ips': [{'ip_address': a} for a in addresses]} + if extra_port_dict: + port_dict.update(extra_port_dict) + name = net_helpers.VethFixture.get_peer_name(machine.port.name) + arp_protect.setup_arp_spoofing_protection(name, port_dict) + self.addCleanup(arp_protect.delete_arp_spoofing_protection, + [name]) + + def test_arp_no_protection(self): + arping(self.source.namespace, self.destination.ip) + arping(self.destination.namespace, self.source.ip) + + def test_arp_correct_protection(self): + self._add_arp_protection(self.source, [self.source.ip]) + self._add_arp_protection(self.destination, [self.destination.ip]) + arping(self.source.namespace, self.destination.ip) + arping(self.destination.namespace, self.source.ip) + + def test_arp_fails_incorrect_protection(self): + self._add_arp_protection(self.source, ['1.1.1.1']) + self._add_arp_protection(self.destination, ['2.2.2.2']) + no_arping(self.source.namespace, self.destination.ip) + no_arping(self.destination.namespace, self.source.ip) + + def test_arp_protection_removal(self): + self._add_arp_protection(self.source, ['1.1.1.1']) + self._add_arp_protection(self.destination, ['2.2.2.2']) + no_arping(self.observer.namespace, self.destination.ip) + no_arping(self.observer.namespace, self.source.ip) + name = net_helpers.VethFixture.get_peer_name(self.source.port.name) + arp_protect.delete_arp_spoofing_protection([name]) + # spoofing should have been removed from source, but not dest + arping(self.observer.namespace, self.source.ip) + no_arping(self.observer.namespace, self.destination.ip) + + def test_arp_protection_update(self): + self._add_arp_protection(self.source, ['1.1.1.1']) + self._add_arp_protection(self.destination, ['2.2.2.2']) + no_arping(self.observer.namespace, self.destination.ip) + no_arping(self.observer.namespace, self.source.ip) + self._add_arp_protection(self.source, ['192.0.0.0/1']) + # spoofing should have been updated on source, but not dest + arping(self.observer.namespace, self.source.ip) + no_arping(self.observer.namespace, self.destination.ip) + + def test_arp_protection_port_security_disabled(self): + self._add_arp_protection(self.source, ['1.1.1.1']) + no_arping(self.observer.namespace, self.source.ip) + self._add_arp_protection(self.source, ['1.1.1.1'], + {'port_security_enabled': False}) + arping(self.observer.namespace, self.source.ip) + + def test_arp_protection_dead_reference_removal(self): + self._add_arp_protection(self.source, ['1.1.1.1']) + self._add_arp_protection(self.destination, ['2.2.2.2']) + no_arping(self.observer.namespace, self.destination.ip) + no_arping(self.observer.namespace, self.source.ip) + name = net_helpers.VethFixture.get_peer_name(self.source.port.name) + # This should remove all arp protect rules that aren't source port + arp_protect.delete_unreferenced_arp_protection([name]) + no_arping(self.observer.namespace, self.source.ip) + arping(self.observer.namespace, self.destination.ip)