Linux Ethernet Bridging - Mar 2021 - [Bridge] [PATCH net-next] net: bridge: when suppression is enabled exclude RARP packets

From: Nikolay Aleksandrov <nikolay at nvidia.com>

Recently we had an interop issue where RARP packets got suppressed with
bridge neigh suppression enabled, but the check in the code was meant to
suppress GARP. Exclude RARP packets from it which would allow some VMWare
setups to work, to quote the report:
"Those RARP packets usually get generated by vMware to notify physical
switches when vMotion occurs. vMware may use random sip/tip or just use
sip=tip=0. So the RARP packet sometimes get properly flooded by the vtep
and other times get dropped by the logic"

Reported-by: Amer Abdalamer <amer at nvidia.com>
Signed-off-by: Nikolay Aleksandrov <nikolay at nvidia.com>
---
Targeting net-next as it's not critical, can be considered an improvement.

 net/bridge/br_arp_nd_proxy.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_arp_nd_proxy.c b/net/bridge/br_arp_nd_proxy.c
index dfec65eca8a6..3db1def4437b 100644
--- a/net/bridge/br_arp_nd_proxy.c
+++ b/net/bridge/br_arp_nd_proxy.c
@@ -160,7 +160,9 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct
net_bridge *br,
 	if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
 		if (p && (p->flags & BR_NEIGH_SUPPRESS))
 			return;
-		if (ipv4_is_zeronet(sip) || sip == tip) {
+		if (parp->ar_op != htons(ARPOP_RREQUEST) &&
+		    parp->ar_op != htons(ARPOP_RREPLY) &&
+		    (ipv4_is_zeronet(sip) || sip == tip)) {
 			/* prevent flooding to neigh suppress ports */
 			BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 			return;
-- 
2.30.2

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Mon, 22 Mar 2021 17:45:27 +0200 you wrote:
> From: Nikolay Aleksandrov <nikolay at nvidia.com>
> 
> Recently we had an interop issue where RARP packets got suppressed with
> bridge neigh suppression enabled, but the check in the code was meant to
> suppress GARP. Exclude RARP packets from it which would allow some VMWare
> setups to work, to quote the report:
> "Those RARP packets usually get generated by vMware to notify physical
> switches when vMotion occurs. vMware may use random sip/tip or just use
> sip=tip=0. So the RARP packet sometimes get properly flooded by the vtep
> and other times get dropped by the logic"
> 
> [...]
Here is the summary with links:
  - [net-next] net: bridge: when suppression is enabled exclude RARP packets
    https://git.kernel.org/netdev/net-next/c/0353b4a96b7a

You are awesome, thank you!
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