Merge branch 'current' into dhcpd

1 files changed, 56 insertions, 52 deletions

diff --git a/src/conf_mode/vrf.py b/src/conf_mode/vrf.py
index 38c0c4463..f79c8a21e 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 added
+            # VRF 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: