1dd35515d4
We have a problem with SNAT with too many connections using the
same source and destination on the network nodes.
In addition we can see in the conntrack table that the who
"instert_failed" increases.
This might be a generic problem with conntrack and linux.
We suspect that we encounter the following "limitation / bug"
in the kernel.
There seems to be a workaround to alleviate this behavior by
setting the -random-fully flag in iptables for port consumption.
This patch fixes the problem by adding the --random-fully to
the SNAT rules.
Conflicts:
neutron/agent/linux/iptables_manager.py
neutron/common/constants.py
neutron/tests/unit/agent/l3/test_agent.py
Change-Id: I246c1f56df889bad9c7e140b56c3614124d80a19
Closes-Bug: #1814002
(cherry picked from commit 30f35e08f9
)
379 lines
16 KiB
Python
379 lines
16 KiB
Python
# Copyright (c) 2015 OpenStack Foundation
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from neutron_lib import constants as lib_constants
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from oslo_log import log as logging
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from neutron.agent.l3 import dvr_local_router
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from neutron.agent.l3 import dvr_snat_ns
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from neutron.agent.l3 import router_info as router
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from neutron.agent.linux import ip_lib
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from neutron.agent.linux import iptables_manager
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from neutron.common import utils as common_utils
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LOG = logging.getLogger(__name__)
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class DvrEdgeRouter(dvr_local_router.DvrLocalRouter):
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def __init__(self, host, *args, **kwargs):
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super(DvrEdgeRouter, self).__init__(host, *args, **kwargs)
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self.snat_namespace = dvr_snat_ns.SnatNamespace(
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self.router_id, self.agent_conf, self.driver, self.use_ipv6)
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self.snat_iptables_manager = None
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def get_gw_ns_name(self):
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return self.snat_namespace.name
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def external_gateway_added(self, ex_gw_port, interface_name):
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super(DvrEdgeRouter, self).external_gateway_added(
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ex_gw_port, interface_name)
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if self._is_this_snat_host():
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self._create_dvr_gateway(ex_gw_port, interface_name)
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# NOTE: When a router is created without a gateway the routes get
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# added to the router namespace, but if we wanted to populate
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# the same routes to the snat namespace after the gateway port
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# is added, we need to call routes_updated here.
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self.routes_updated([], self.router['routes'])
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elif self.snat_namespace.exists():
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# This is the case where the snat was moved manually or
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# rescheduled to a different agent when the agent was dead.
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LOG.debug("SNAT was moved or rescheduled to a different host "
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"and does not match with the current host. This is "
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"a stale namespace %s and will be cleared from the "
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"current dvr_snat host.", self.snat_namespace.name)
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self.external_gateway_removed(ex_gw_port, interface_name)
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def _list_centralized_floating_ip_cidrs(self):
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# Compute a list of addresses this gw is supposed to have.
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# This avoids unnecessarily removing those addresses and
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# causing a momentarily network outage.
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floating_ips = self.get_floating_ips()
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return [common_utils.ip_to_cidr(ip['floating_ip_address'])
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for ip in floating_ips
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if ip.get(lib_constants.DVR_SNAT_BOUND)]
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def external_gateway_updated(self, ex_gw_port, interface_name):
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if not self._is_this_snat_host():
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# no centralized SNAT gateway for this node/agent
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LOG.debug("not hosting snat for router: %s", self.router['id'])
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if self.snat_namespace.exists():
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LOG.debug("SNAT was rescheduled to host %s. Clearing snat "
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"namespace.", self.router.get('gw_port_host'))
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return self.external_gateway_removed(
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ex_gw_port, interface_name)
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return
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if not self.snat_namespace.exists():
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# SNAT might be rescheduled to this agent; need to process like
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# newly created gateway
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return self.external_gateway_added(ex_gw_port, interface_name)
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else:
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preserve_ips = self._list_centralized_floating_ip_cidrs()
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self._external_gateway_added(ex_gw_port,
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interface_name,
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self.snat_namespace.name,
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preserve_ips)
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def _external_gateway_removed(self, ex_gw_port, interface_name):
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super(DvrEdgeRouter, self).external_gateway_removed(ex_gw_port,
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interface_name)
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if not self._is_this_snat_host() and not self.snat_namespace.exists():
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# no centralized SNAT gateway for this node/agent
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LOG.debug("not hosting snat for router: %s", self.router['id'])
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return
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self.driver.unplug(interface_name,
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bridge=self.agent_conf.external_network_bridge,
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namespace=self.snat_namespace.name,
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prefix=router.EXTERNAL_DEV_PREFIX)
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def external_gateway_removed(self, ex_gw_port, interface_name):
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self._external_gateway_removed(ex_gw_port, interface_name)
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if self.snat_namespace.exists():
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self.snat_namespace.delete()
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def internal_network_added(self, port):
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super(DvrEdgeRouter, self).internal_network_added(port)
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# TODO(gsagie) some of this checks are already implemented
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# in the base class, think how to avoid re-doing them
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if not self._is_this_snat_host():
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return
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sn_port = self.get_snat_port_for_internal_port(port)
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if not sn_port:
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return
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ns_name = dvr_snat_ns.SnatNamespace.get_snat_ns_name(self.router['id'])
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interface_name = self._get_snat_int_device_name(sn_port['id'])
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self._internal_network_added(
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ns_name,
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sn_port['network_id'],
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sn_port['id'],
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sn_port['fixed_ips'],
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sn_port['mac_address'],
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interface_name,
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lib_constants.SNAT_INT_DEV_PREFIX,
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mtu=sn_port.get('mtu'))
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def _dvr_internal_network_removed(self, port):
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super(DvrEdgeRouter, self)._dvr_internal_network_removed(port)
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if not self.ex_gw_port:
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return
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sn_port = self.get_snat_port_for_internal_port(port, self.snat_ports)
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if not sn_port:
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return
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if not self._is_this_snat_host():
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return
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snat_interface = self._get_snat_int_device_name(sn_port['id'])
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ns_name = self.snat_namespace.name
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prefix = lib_constants.SNAT_INT_DEV_PREFIX
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if ip_lib.device_exists(snat_interface, namespace=ns_name):
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self.driver.unplug(snat_interface, namespace=ns_name,
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prefix=prefix)
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def _plug_snat_port(self, port):
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interface_name = self._get_snat_int_device_name(port['id'])
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self._internal_network_added(
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self.snat_namespace.name, port['network_id'],
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port['id'], port['fixed_ips'],
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port['mac_address'], interface_name,
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lib_constants.SNAT_INT_DEV_PREFIX,
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mtu=port.get('mtu'))
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def _create_dvr_gateway(self, ex_gw_port, gw_interface_name):
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snat_ns = self._create_snat_namespace()
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# connect snat_ports to br_int from SNAT namespace
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for port in self.get_snat_interfaces():
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self._plug_snat_port(port)
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self._external_gateway_added(ex_gw_port, gw_interface_name,
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snat_ns.name, preserve_ips=[])
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self.snat_iptables_manager = iptables_manager.IptablesManager(
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namespace=snat_ns.name,
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use_ipv6=self.use_ipv6)
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self._initialize_address_scope_iptables(self.snat_iptables_manager)
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def _create_snat_namespace(self):
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"""Create SNAT namespace."""
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# TODO(mlavalle): in the near future, this method should contain the
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# code in the L3 agent that creates a gateway for a dvr. The first step
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# is to move the creation of the snat namespace here
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self.snat_namespace.create()
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return self.snat_namespace
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def _get_snat_int_device_name(self, port_id):
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long_name = lib_constants.SNAT_INT_DEV_PREFIX + port_id
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return long_name[:self.driver.DEV_NAME_LEN]
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def _is_this_snat_host(self):
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host = self.router.get('gw_port_host')
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if not host:
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LOG.debug("gw_port_host missing from router: %s",
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self.router['id'])
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return host == self.host
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def _handle_router_snat_rules(self, ex_gw_port, interface_name):
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super(DvrEdgeRouter, self)._handle_router_snat_rules(
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ex_gw_port, interface_name)
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if not self._is_this_snat_host():
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return
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if not self.get_ex_gw_port():
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return
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if not self.snat_iptables_manager:
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LOG.debug("DVR router: no snat rules to be handled")
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return
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with self.snat_iptables_manager.defer_apply():
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self._empty_snat_chains(self.snat_iptables_manager)
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# NOTE: float-snat should be added for the
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# centralized floating-ips supported by the
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# snat namespace.
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self.snat_iptables_manager.ipv4['nat'].add_rule(
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'snat', '-j $float-snat')
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self._add_snat_rules(ex_gw_port, self.snat_iptables_manager,
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interface_name)
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def update_routing_table(self, operation, route):
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if self.get_ex_gw_port() and self._is_this_snat_host():
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ns_name = self.snat_namespace.name
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# NOTE: For now let us apply the static routes both in SNAT
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# namespace and Router Namespace, to reduce the complexity.
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if self.snat_namespace.exists():
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super(DvrEdgeRouter, self)._update_routing_table(
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operation, route, namespace=ns_name)
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else:
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LOG.error("The SNAT namespace %s does not exist for "
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"the router.", ns_name)
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super(DvrEdgeRouter, self).update_routing_table(operation, route)
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def delete(self):
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super(DvrEdgeRouter, self).delete()
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if self.snat_namespace.exists():
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self.snat_namespace.delete()
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def process_address_scope(self):
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super(DvrEdgeRouter, self).process_address_scope()
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if not self._is_this_snat_host():
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return
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if not self.snat_iptables_manager:
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LOG.debug("DVR router: no snat rules to be handled")
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return
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# Prepare address scope iptables rule for dvr snat interfaces
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internal_ports = self.get_snat_interfaces()
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ports_scopemark = self._get_port_devicename_scopemark(
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internal_ports, self._get_snat_int_device_name)
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# Prepare address scope iptables rule for external port
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external_port = self.get_ex_gw_port()
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if external_port:
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external_port_scopemark = self._get_port_devicename_scopemark(
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[external_port], self.get_external_device_name)
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for ip_version in (lib_constants.IP_VERSION_4,
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lib_constants.IP_VERSION_6):
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ports_scopemark[ip_version].update(
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external_port_scopemark[ip_version])
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with self.snat_iptables_manager.defer_apply():
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self._add_address_scope_mark(
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self.snat_iptables_manager, ports_scopemark)
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def _delete_stale_external_devices(self, interface_name):
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if not self.snat_namespace.exists():
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return
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ns_ip = ip_lib.IPWrapper(namespace=self.snat_namespace.name)
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for d in ns_ip.get_devices():
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if (d.name.startswith(router.EXTERNAL_DEV_PREFIX) and
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d.name != interface_name):
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LOG.debug('Deleting stale external router device: %s', d.name)
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self.driver.unplug(
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d.name,
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bridge=self.agent_conf.external_network_bridge,
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namespace=self.snat_namespace.name,
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prefix=router.EXTERNAL_DEV_PREFIX)
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def get_snat_external_device_interface_name(self, ex_gw_port):
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long_name = router.EXTERNAL_DEV_PREFIX + ex_gw_port['id']
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return long_name[:self.driver.DEV_NAME_LEN]
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def get_centralized_fip_cidr_set(self):
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"""Returns the fip_cidr set for centralized floatingips."""
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ex_gw_port = self.get_ex_gw_port()
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# Don't look for centralized FIP cidrs if gw_port not exists or
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# this is not snat host
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if (not ex_gw_port or not self._is_this_snat_host() or
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not self.snat_namespace.exists()):
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return set()
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interface_name = self.get_snat_external_device_interface_name(
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ex_gw_port)
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device = ip_lib.IPDevice(
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interface_name, namespace=self.snat_namespace.name)
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return set([addr['cidr'] for addr in device.addr.list()])
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def get_router_cidrs(self, device):
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"""Over-ride the get_router_cidrs function to return the list.
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This function is overridden to provide the complete list of
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floating_ip cidrs that the router hosts.
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This includes the centralized floatingip cidr list and the
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regular floatingip cidr list that are bound to fip namespace.
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"""
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fip_cidrs = super(DvrEdgeRouter, self).get_router_cidrs(device)
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centralized_cidrs = self.get_centralized_fip_cidr_set()
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return fip_cidrs | centralized_cidrs
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def remove_centralized_floatingip(self, fip_cidr):
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"""Function to handle the centralized Floatingip remove."""
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if not self.get_ex_gw_port():
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return
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if not self._is_this_snat_host():
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return
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interface_name = self.get_snat_external_device_interface_name(
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self.get_ex_gw_port())
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device = ip_lib.IPDevice(
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interface_name, namespace=self.snat_namespace.name)
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device.delete_addr_and_conntrack_state(fip_cidr)
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self.process_floating_ip_nat_rules_for_centralized_floatingip()
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def add_centralized_floatingip(self, fip, fip_cidr):
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"""Function to handle the centralized Floatingip addition."""
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if not self.get_ex_gw_port():
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return
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if not self._is_this_snat_host():
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return
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interface_name = self.get_snat_external_device_interface_name(
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self.get_ex_gw_port())
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try:
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ip_lib.add_ip_address(fip_cidr, interface_name,
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namespace=self.snat_namespace.name)
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except ip_lib.IpAddressAlreadyExists:
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pass
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except RuntimeError:
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LOG.warning("Unable to configure IP address for centralized "
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"floating IP: %s", fip['id'])
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return lib_constants.FLOATINGIP_STATUS_ERROR
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self.process_floating_ip_nat_rules_for_centralized_floatingip()
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# Send a GARP message on the external interface for the
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# centralized floatingip configured.
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ip_lib.send_ip_addr_adv_notif(self.snat_namespace.name,
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interface_name,
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fip['floating_ip_address'])
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return lib_constants.FLOATINGIP_STATUS_ACTIVE
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def _centralized_floating_forward_rules(self, floating_ip, fixed_ip):
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to_source = '-s %s/32 -j SNAT --to-source %s' % (fixed_ip, floating_ip)
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if self.snat_iptables_manager.random_fully:
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to_source += ' --random-fully'
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return [('PREROUTING', '-d %s/32 -j DNAT --to-destination %s' %
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(floating_ip, fixed_ip)),
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('OUTPUT', '-d %s/32 -j DNAT --to-destination %s' %
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(floating_ip, fixed_ip)),
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('float-snat', to_source)]
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def _set_floating_ip_nat_rules_for_centralized_floatingip(self, fip):
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if fip.get(lib_constants.DVR_SNAT_BOUND):
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fixed = fip['fixed_ip_address']
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fip_ip = fip['floating_ip_address']
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for chain, rule in self._centralized_floating_forward_rules(
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fip_ip, fixed):
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self.snat_iptables_manager.ipv4['nat'].add_rule(
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chain, rule, tag='floating_ip')
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def process_floating_ip_nat_rules_for_centralized_floatingip(self):
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self.snat_iptables_manager.ipv4['nat'].clear_rules_by_tag(
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'floating_ip')
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floating_ips = self.get_floating_ips()
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for fip in floating_ips:
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self._set_floating_ip_nat_rules_for_centralized_floatingip(fip)
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self.snat_iptables_manager.apply()
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def process_floating_ip_nat_rules(self):
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if self._is_this_snat_host():
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self.process_floating_ip_nat_rules_for_centralized_floatingip()
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# Cover mixed dvr_snat and compute node, aka a dvr_snat node has both
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# centralized and distributed floating IPs.
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super(DvrEdgeRouter, self).process_floating_ip_nat_rules()
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