vrf: T591: define sysctl setting for net.vrf.strict_mode

Enable/Disable VRF strict mode, when net.vrf.strict_mode=0 (default) it is
possible to associate multiple VRF devices to the same table. Conversely, when
net.vrf.strict_mode=1 a table can be associated to a single VRF device.

A VRF table can be used by the VyOS CLI only once (ensured by verify()), this
simply adds an additional Kernel safety net, but a requirement for IPv6 segment
routing headers.

(cherry picked from commit 10701108fecb36f7be7eb7ef5f1e54e63da5fb4e)

3 files changed, 25 insertions, 16 deletions

diff --git a/smoketest/scripts/cli/test_vrf.py b/smoketest/scripts/cli/test_vrf.py
index bb91eddea..6207a1b41 100755
--- a/smoketest/scripts/cli/test_vrf.py
+++ b/smoketest/scripts/cli/test_vrf.py
@@ -30,6 +30,7 @@ from vyos.utils.process import cmd
 from vyos.utils.file import read_file
 from vyos.utils.network import get_interface_config
 from vyos.utils.network import is_intf_addr_assigned
+from vyos.utils.system import sysctl_read
 
 base_path = ['vrf']
 vrfs = ['red', 'green', 'blue', 'foo-bar', 'baz_foo']
@@ -58,6 +59,8 @@ class VRFTest(VyOSUnitTestSHIM.TestCase):
         self.cli_commit()
         for vrf in vrfs:
             self.assertNotIn(vrf, interfaces())
+        # If there is no VRF defined, strict_mode should be off
+        self.assertEqual(sysctl_read('net.vrf.strict_mode'), '0')
 
     def test_vrf_vni_and_table_id(self):
         base_table = '1000'
@@ -130,8 +133,9 @@ class VRFTest(VyOSUnitTestSHIM.TestCase):
             # Ensure VRF was created
             self.assertIn(vrf, interfaces())
             # Verify IP forwarding is 1 (enabled)
-            self.assertEqual(read_file(f'/proc/sys/net/ipv4/conf/{vrf}/forwarding'), '1')
-            self.assertEqual(read_file(f'/proc/sys/net/ipv6/conf/{vrf}/forwarding'), '1')
+            self.assertEqual(sysctl_read(f'net.ipv4.conf.{vrf}.forwarding'), '1')
+            self.assertEqual(sysctl_read(f'net.ipv6.conf.{vrf}.forwarding'), '1')
+
             # Test for proper loopback IP assignment
             for addr in loopbacks:
                 self.assertTrue(is_intf_addr_assigned(vrf, addr))
@@ -149,10 +153,11 @@ class VRFTest(VyOSUnitTestSHIM.TestCase):
         self.cli_commit()
 
         # Verify VRF configuration
-        tmp = read_file('/proc/sys/net/ipv4/tcp_l3mdev_accept')
-        self.assertIn(tmp, '1')
-        tmp = read_file('/proc/sys/net/ipv4/udp_l3mdev_accept')
-        self.assertIn(tmp, '1')
+        self.assertEqual(sysctl_read('net.ipv4.tcp_l3mdev_accept'), '1')
+        self.assertEqual(sysctl_read('net.ipv4.udp_l3mdev_accept'), '1')
+
+        # If there is any VRF defined, strict_mode should be on
+        self.assertEqual(sysctl_read('net.vrf.strict_mode'), '1')
 
     def test_vrf_table_id_is_unalterable(self):
         # Linux Kernel prohibits the change of a VRF table  on the fly.
@@ -290,8 +295,8 @@ class VRFTest(VyOSUnitTestSHIM.TestCase):
             # Ensure VRF was created
             self.assertIn(vrf, interfaces())
             # Verify IP forwarding is 0 (disabled)
-            self.assertEqual(read_file(f'/proc/sys/net/ipv4/conf/{vrf}/forwarding'), '0')
-            self.assertEqual(read_file(f'/proc/sys/net/ipv6/conf/{vrf}/forwarding'), '0')
+            self.assertEqual(sysctl_read(f'net.ipv4.conf.{vrf}.forwarding'), '0')
+            self.assertEqual(sysctl_read(f'net.ipv6.conf.{vrf}.forwarding'), '0')
 
     def test_vrf_ip_protocol_route_map(self):
         table = '6000'
diff --git a/src/conf_mode/vrf.py b/src/conf_mode/vrf.py
index 37625142c..9b1b6355f 100755
--- a/src/conf_mode/vrf.py
+++ b/src/conf_mode/vrf.py
@@ -214,6 +214,18 @@ def apply(vrf):
             # Delete the VRF Kernel interface
             call(f'ip link delete dev {tmp}')
 
+    # Enable/Disable VRF strict mode
+    # When net.vrf.strict_mode=0 (default) it is possible to associate multiple
+    # VRF devices to the same table. Conversely, when net.vrf.strict_mode=1 a
+    # table can be associated to a single VRF device.
+    #
+    # A VRF table can be used by the VyOS CLI only once (ensured by verify()),
+    # this simply adds an additional Kernel safety net
+    strict_mode = '0'
+    # Set to 1 if any VRF is defined
+    if 'name' in vrf: strict_mode = '1'
+    sysctl_write('net.vrf.strict_mode', strict_mode)
+
     if 'name' in vrf:
         # Separate VRFs in conntrack table
         # check if table already exists
diff --git a/src/etc/sysctl.d/30-vyos-router.conf b/src/etc/sysctl.d/30-vyos-router.conf
index 67d96969e..1c9b8999f 100644
--- a/src/etc/sysctl.d/30-vyos-router.conf
+++ b/src/etc/sysctl.d/30-vyos-router.conf
@@ -105,11 +105,3 @@ net.core.rps_sock_flow_entries = 32768
 net.core.default_qdisc=fq_codel
 net.ipv4.tcp_congestion_control=bbr
 
-# VRF - Virtual routing and forwarding
-# When net.vrf.strict_mode=0 (default) it is possible to associate multiple
-# VRF devices to the same table. Conversely, when net.vrf.strict_mode=1 a
-# table can be associated to a single VRF device.
-#
-# A VRF table can be used by the VyOS CLI only once (ensured by verify()),
-# this simply adds an additional Kernel safety net
-net.vrf.strict_mode=1