diff options
| -rwxr-xr-x | src/conf_mode/vrf.py | 105 |
1 files changed, 53 insertions, 52 deletions
diff --git a/src/conf_mode/vrf.py b/src/conf_mode/vrf.py index 9d36819be..e64f35ab5 100755 --- a/src/conf_mode/vrf.py +++ b/src/conf_mode/vrf.py @@ -1,6 +1,6 @@ #!/usr/bin/env python3 # -# Copyright (C) 2020-2021 VyOS maintainers and contributors +# Copyright (C) 2020-2022 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 @@ -26,16 +26,23 @@ from vyos.template import render from vyos.util import call from vyos.util import cmd from vyos.util import dict_search +from vyos.util import sysctl from vyos import ConfigError from vyos import airbag airbag.enable() config_file = r'/etc/iproute2/rt_tables.d/vyos-vrf.conf' -def list_rules(): - command = 'ip -j -4 rule show' - answer = loads(cmd(command)) - return [_ for _ in answer if _] +def has_rule(af : str, priority : int, table : str): + """ Check if a given ip rule exists """ + if af not in ['-4', '-6']: + raise ValueError() + command = f'ip -j {af} rule show' + for tmp in loads(cmd(command)): + if {'priority', 'table'} <= set(tmp): + if tmp['priority'] == priority and tmp['table'] == table: + return True + return False def vrf_interfaces(c, match): matched = [] @@ -64,7 +71,6 @@ def vrf_routing(c, match): c.set_level(old_level) return matched - def get_config(config=None): if config: conf = config @@ -138,36 +144,63 @@ def apply(vrf): bind_all = '0' if 'bind-to-all' in vrf: bind_all = '1' - call(f'sysctl -wq net.ipv4.tcp_l3mdev_accept={bind_all}') - call(f'sysctl -wq net.ipv4.udp_l3mdev_accept={bind_all}') + sysctl('net.ipv4.tcp_l3mdev_accept', bind_all) + sysctl('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}'): - call(f'ip -4 route del vrf {tmp} unreachable default metric 4278198272') - call(f'ip -6 route del vrf {tmp} unreachable default metric 4278198272') call(f'ip link delete dev {tmp}') if 'name' in vrf: + # 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 further down once VRFs + # are enabled. + # + # Thanks to https://stbuehler.de/blog/article/2020/02/29/using_vrf__virtual_routing_and_forwarding__on_linux.html + + for afi in ['-4', '-6']: + # move lookup local to pref 32765 (from 0) + if not has_rule(afi, 32765, 'local'): + call(f'ip {afi} rule add pref 32765 table local') + if has_rule(afi, 0, 'local'): + call(f'ip {afi} rule del pref 0') + # make sure that in VRFs after failed lookup in the VRF specific table + # nothing else is reached + if not has_rule(afi, 1000, 'l3mdev'): + # this should be added by the kernel when a VRF is created + # add it here for completeness + call(f'ip {afi} rule add pref 1000 l3mdev protocol kernel') + + # add another rule with an unreachable target which only triggers in VRF context + # if a route could not be reached + if not has_rule(afi, 2000, 'l3mdev'): + call(f'ip {afi} rule add pref 2000 l3mdev unreachable') + 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 call(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. - call(f'ip -4 route add vrf {name} unreachable default metric 4278198272') - call(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) - call(f'ip -4 addr add 127.0.0.1/8 dev {name}') - call(f'ip -6 addr add ::1/128 dev {name}') # set VRF description for e.g. SNMP monitoring vrf_if = Interface(name) + # We also should add proper loopback IP addresses to the newly + # created VRFs for services bound to the loopback address (SNMP, NTP) + vrf_if.add_addr('127.0.0.1/8') + vrf_if.add_addr('::1/128') + # add VRF description if available 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 @@ -178,38 +211,6 @@ def apply(vrf): 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']: - call(f'ip {af} rule add pref 32765 table local') - call(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']: - call(f'ip {af} rule add pref 0 table local') - call(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]: - call(f'ip {af} rule del pref 1000') - return None if __name__ == '__main__': |