From 3a00afdc5db9be07b09201c51e0a7df3748c7f12 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Thu, 4 Jan 2024 15:25:01 +0100 Subject: [PATCH] net: bridge: do not send arp replies if src and target hw addr is the same There are broken devices in the wild that handle duplicate IP address detection by sending out ARP requests for the IP that they received from a DHCP server and refuse the address if they get a reply. When proxyarp is enabled, they would go into a loop of requesting an address and then NAKing it again. Link: https://github.com/openwrt/openwrt/issues/14309 Signed-off-by: Felix Fietkau Signed-off-by: NipaLocal --- net/bridge/br_arp_nd_proxy.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_arp_nd_proxy.c b/net/bridge/br_arp_nd_proxy.c index c7869a286df401..3a277093837437 100644 --- a/net/bridge/br_arp_nd_proxy.c +++ b/net/bridge/br_arp_nd_proxy.c @@ -204,7 +204,10 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br, if ((p && (p->flags & BR_PROXYARP)) || (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)) || br_is_neigh_suppress_enabled(f->dst, vid)) { - if (!vid) + replied = true; + if (!memcmp(n->ha, sha, dev->addr_len)) + replied = false; + else if (!vid) br_arp_send(br, p, skb->dev, sip, tip, sha, n->ha, sha, 0, 0); else @@ -212,7 +215,6 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br, sha, n->ha, sha, skb->vlan_proto, skb_vlan_tag_get(skb)); - replied = true; } /* If we have replied or as long as we know the