From 85a5a8a0c974dfb43adcbb0d096c2f3ebf271669 Mon Sep 17 00:00:00 2001
From: "Joshua M. Boniface" <joshua@boniface.me>
Date: Mon, 24 Jun 2019 16:35:52 -0400
Subject: [PATCH] Disable tx offloading on bridge interfaces

Reference: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717215#68

Without this, DHCP fails when traversing only the local bridge, for
Debian Jessie or earlier (and possibly other OSes as well), due to the
missing UDP checksums. This disables the offload and hence reenables
the checksums even on the software-only bridge.

Also rearranged the steps and added comments arround this section to
better clarify what each command is doing.
---
 node-daemon/pvcd/VXNetworkInstance.py | 56 ++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 14 deletions(-)

diff --git a/node-daemon/pvcd/VXNetworkInstance.py b/node-daemon/pvcd/VXNetworkInstance.py
index a511f8f3..03445b53 100644
--- a/node-daemon/pvcd/VXNetworkInstance.py
+++ b/node-daemon/pvcd/VXNetworkInstance.py
@@ -420,6 +420,8 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
             prefix='VNI {}'.format(self.vni),
             state='o'
         )
+
+        # Create vLAN interface
         common.run_os_command(
             'ip link add link {} name {} type vlan id {}'.format(
                 self.vni_dev,
@@ -427,18 +429,14 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
                 self.vni
             )
         )
+        # Create bridge interface
         common.run_os_command(
             'brctl addbr {}'.format(
                 self.bridge_nic
             )
         )
-        common.run_os_command(
-            'brctl addif {} {}'.format(
-                self.bridge_nic,
-                self.vlan_nic
-            )
-        )
 
+        # Set MTU of vLAN and bridge NICs
         vx_mtu = self.vni_mtu
         common.run_os_command(
             'ip link set {} mtu {} up'.format(
@@ -452,13 +450,29 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
                 vx_mtu
             )
         )
+
+        # Disable tx checksum offload on bridge interface (breaks DHCP on Debian < 9)
+        common.run_os_command(
+            'ethtool -K {} tx off'.format(
+                self.bridge_nic
+            )
+        )
+
+        # Disable IPv6 DAD on bridge interface
         common.run_os_command(
-            # Disable IPv6 DAD on bridge NICs
             'sysctl net.ipv6.conf.{}.accept_dad=0'.format(
                 self.bridge_nic
             )
         )
 
+        # Add vLAN interface to bridge interface
+        common.run_os_command(
+            'brctl addif {} {}'.format(
+                self.bridge_nic,
+                self.vlan_nic
+            )
+        )
+
     # Create managed network configuration
     def createNetworkManaged(self):
         self.logger.out(
@@ -468,6 +482,8 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
             prefix='VNI {}'.format(self.vni),
             state='o'
         )
+
+        # Create VXLAN interface
         common.run_os_command(
             'ip link add {} type vxlan id {} dstport 4789 dev {}'.format(
                 self.vxlan_nic,
@@ -475,18 +491,14 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
                 self.vni_dev
             )
         )
+        # Create bridge interface
         common.run_os_command(
             'brctl addbr {}'.format(
                 self.bridge_nic
             )
         )
-        common.run_os_command(
-            'brctl addif {} {}'.format(
-                self.bridge_nic,
-                self.vxlan_nic
-            )
-        )
 
+        # Set MTU of VXLAN and bridge NICs
         vx_mtu = self.vni_mtu - 50
         common.run_os_command(
             'ip link set {} mtu {} up'.format(
@@ -500,13 +512,29 @@ add rule inet filter forward ip6 saddr {netaddr6} counter jump {vxlannic}-out
                 vx_mtu
             )
         )
+
+        # Disable tx checksum offload on bridge interface (breaks DHCP on Debian < 9)
+        common.run_os_command(
+            'ethtool -K {} tx off'.format(
+                self.bridge_nic
+            )
+        )
+
+        # Disable IPv6 DAD on bridge interface
         common.run_os_command(
-            # Disable IPv6 DAD on bridge NICs
             'sysctl net.ipv6.conf.{}.accept_dad=0'.format(
                 self.bridge_nic
             )
         )
 
+        # Add VXLAN interface to bridge interface
+        common.run_os_command(
+            'brctl addif {} {}'.format(
+                self.bridge_nic,
+                self.vxlan_nic
+            )
+        )
+
     def createFirewall(self):
         if self.nettype == 'managed':
             # For future use