#!/usr/bin/env python3 # # Copyright (C) 2020-2021 VyOS maintainers and contributors # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License version 2 or later as # published by the Free Software Foundation. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . import os from sys import exit from json import loads from vyos.config import Config from vyos.configdict import node_changed from vyos.ifconfig import Interface from vyos.template import render from vyos.util import cmd from vyos.util import dict_search from vyos import ConfigError from vyos import airbag airbag.enable() config_file = r'/etc/iproute2/rt_tables.d/vyos-vrf.conf' def _cmd(command): cmd(command, raising=ConfigError, message='Error changing VRF') def list_rules(): command = 'ip -j -4 rule show' answer = loads(cmd(command)) return [_ for _ in answer if _] def vrf_interfaces(c, match): matched = [] old_level = c.get_level() c.set_level(['interfaces']) section = c.get_config_dict([], get_first_key=True) for type in section: interfaces = section[type] for name in interfaces: interface = interfaces[name] if 'vrf' in interface: v = interface.get('vrf', '') if v == match: matched.append(name) c.set_level(old_level) return matched def vrf_routing(c, match): matched = [] old_level = c.get_level() c.set_level(['protocols', 'vrf']) if match in c.list_nodes([]): matched.append(match) c.set_level(old_level) return matched def get_config(config=None): if config: conf = config else: conf = Config() base = ['vrf'] vrf = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True) # determine which VRF has been removed tmp = node_changed(conf, base + ['name']) for name in tmp: vrf.update({'vrf_remove' : { name : ''}}) # get VRF bound interfaces interfaces = vrf_interfaces(conf, name) if interfaces: vrf.update({'vrf_remove' : { name : {'interfaces' : ''}}}) # get VRF bound routing instances routes = vrf_routing(conf, name) if routes: vrf.update({'vrf_remove' : { name : {'routes' : routes}}}) return vrf def verify(vrf): # ensure VRF is not assigned to any interface if 'vrf_remove' in vrf: for name, config in vrf['vrf_remove'].items(): if 'interfaces' in config: raise ConfigError(f'Can not remove VRF "{name}", it still has '\ f'member interfaces!') if 'routes' in config: raise ConfigError(f'Can not remove VRF "{name}", it still has '\ f'static routes installed!') if 'name' in vrf: table_ids = [] for name, config in vrf['name'].items(): # table id is mandatory if 'table' not in config: raise ConfigError(f'VRF "{name}" table id is mandatory!') # routing table id can't be changed - OS restriction if os.path.isdir(f'/sys/class/net/{name}'): tmp = loads(cmd(f'ip -j -d link show {name}'))[0] tmp = str(dict_search('linkinfo.info_data.table', tmp)) if tmp and tmp != config['table']: raise ConfigError(f'VRF "{name}" table id modification not possible!') # VRf routing table ID must be unique on the system if config['table'] in table_ids: raise ConfigError(f'VRF "{name}" table id is not unique!') table_ids.append(config['table']) return None def generate(vrf): render(config_file, 'vrf/vrf.conf.tmpl', vrf) return None def apply(vrf): # Documentation # # - https://github.com/torvalds/linux/blob/master/Documentation/networking/vrf.txt # - https://github.com/Mellanox/mlxsw/wiki/Virtual-Routing-and-Forwarding-(VRF) # - https://github.com/Mellanox/mlxsw/wiki/L3-Tunneling # - https://netdevconf.info/1.1/proceedings/slides/ahern-vrf-tutorial.pdf # - https://netdevconf.info/1.2/slides/oct6/02_ahern_what_is_l3mdev_slides.pdf # set the default VRF global behaviour bind_all = '0' if 'bind_to_all' in vrf: bind_all = '1' _cmd(f'sysctl -wq net.ipv4.tcp_l3mdev_accept={bind_all}') _cmd(f'sysctl -wq net.ipv4.udp_l3mdev_accept={bind_all}') for tmp in (dict_search('vrf_remove', vrf) or []): if os.path.isdir(f'/sys/class/net/{tmp}'): _cmd(f'ip -4 route del vrf {tmp} unreachable default metric 4278198272') _cmd(f'ip -6 route del vrf {tmp} unreachable default metric 4278198272') _cmd(f'ip link delete dev {tmp}') if 'name' in vrf: for name, config in vrf['name'].items(): table = config['table'] if not os.path.isdir(f'/sys/class/net/{name}'): # For each VRF apart from your default context create a VRF # interface with a separate routing table _cmd(f'ip link add {name} type vrf table {table}') # The kernel Documentation/networking/vrf.txt also recommends # adding unreachable routes to the VRF routing tables so that routes # afterwards are taken. _cmd(f'ip -4 route add vrf {name} unreachable default metric 4278198272') _cmd(f'ip -6 route add vrf {name} unreachable default metric 4278198272') # We also should add proper loopback IP addresses to the newly # created VRFs for services bound to the loopback address (SNMP, NTP) _cmd(f'ip -4 addr add 127.0.0.1/8 dev {name}') _cmd(f'ip -6 addr add ::1/128 dev {name}') # set VRF description for e.g. SNMP monitoring vrf_if = Interface(name) vrf_if.set_alias(config.get('description', '')) # Enable/Disable of an interface must always be done at the end of the # derived class to make use of the ref-counting set_admin_state() # function. We will only enable the interface if 'up' was called as # often as 'down'. This is required by some interface implementations # as certain parameters can only be changed when the interface is # in admin-down state. This ensures the link does not flap during # reconfiguration. state = 'down' if 'disable' in config else 'up' vrf_if.set_admin_state(state) # Linux routing uses rules to find tables - routing targets are then # looked up in those tables. If the lookup got a matching route, the # process ends. # # TL;DR; first table with a matching entry wins! # # You can see your routing table lookup rules using "ip rule", sadly the # local lookup is hit before any VRF lookup. Pinging an addresses from the # VRF will usually find a hit in the local table, and never reach the VRF # routing table - this is usually not what you want. Thus we will # re-arrange the tables and move the local lookup furhter down once VRFs # are enabled. # get current preference on local table local_pref = [r.get('priority') for r in list_rules() if r.get('table') == 'local'][0] # change preference when VRFs are enabled and local lookup table is default if not local_pref and 'name' in vrf: for af in ['-4', '-6']: _cmd(f'ip {af} rule add pref 32765 table local') _cmd(f'ip {af} rule del pref 0') # return to default lookup preference when no VRF is configured if 'name' not in vrf: for af in ['-4', '-6']: _cmd(f'ip {af} rule add pref 0 table local') _cmd(f'ip {af} rule del pref 32765') # clean out l3mdev-table rule if present if 1000 in [r.get('priority') for r in list_rules() if r.get('priority') == 1000]: _cmd(f'ip {af} rule del pref 1000') return None if __name__ == '__main__': try: c = get_config() verify(c) generate(c) apply(c) except ConfigError as e: print(e) exit(1)