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-rwxr-xr-xsrc/conf_mode/vrf.py108
1 files changed, 56 insertions, 52 deletions
diff --git a/src/conf_mode/vrf.py b/src/conf_mode/vrf.py
index 38c0c4463..6a521a0dd 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
@@ -29,6 +29,7 @@ from vyos.util import dict_search
from vyos.util import get_interface_config
from vyos.util import popen
from vyos.util import run
+from vyos.util import sysctl_write
from vyos import ConfigError
from vyos import frr
from vyos import airbag
@@ -37,10 +38,16 @@ airbag.enable()
config_file = '/etc/iproute2/rt_tables.d/vyos-vrf.conf'
nft_vrf_config = '/tmp/nftables-vrf-zones'
-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 = []
@@ -69,7 +76,6 @@ def vrf_routing(c, match):
c.set_level(old_level)
return matched
-
def get_config(config=None):
if config:
conf = config
@@ -148,13 +154,11 @@ 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_write('net.ipv4.tcp_l3mdev_accept', bind_all)
+ sysctl_write('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}')
# Remove nftables conntrack zone map item
nft_del_element = f'delete element inet vrf_zones ct_iface_map {{ "{tmp}" }}'
@@ -165,31 +169,59 @@ def apply(vrf):
# check if table already exists
_, err = popen('nft list table inet vrf_zones')
# If not, create a table
- if err:
- if os.path.exists(nft_vrf_config):
- cmd(f'nft -f {nft_vrf_config}')
- os.unlink(nft_vrf_config)
+ if err and os.path.exists(nft_vrf_config):
+ cmd(f'nft -f {nft_vrf_config}')
+ os.unlink(nft_vrf_config)
+
+ # 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
@@ -203,37 +235,9 @@ def apply(vrf):
nft_add_element = f'add element inet vrf_zones ct_iface_map {{ "{name}" : {table} }}'
cmd(f'nft {nft_add_element}')
- # 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')
# Remove VRF zones table from nftables
tmp = run('nft list table inet vrf_zones')
if tmp == 0: