netdev - [PATCH net-next] net: bridge: when suppression is enabled exclude RARP packets

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Message-Id: <20210322154527.224886-1-razor@blackwall.org>
Date:   Mon, 22 Mar 2021 17:45:27 +0200
From:   Nikolay Aleksandrov <razor@...ckwall.org>
To:     netdev@...r.kernel.org
Cc:     roopa@...dia.com, bridge@...ts.linux-foundation.org,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Amer Abdalamer <amer@...dia.com>
Subject: [PATCH net-next] net: bridge: when suppression is enabled exclude RARP packets

From: Nikolay Aleksandrov <nikolay@...dia.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@...dia.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@...dia.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