target/linux/generic/pending-6.1/151-net-bridge-do-not-send-arp-replies-if-src-and-target.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Thu, 4 Jan 2024 15:21:21 +0100
   3 Subject: [PATCH] net: bridge: do not send arp replies if src and target hw
   4  addr is the same
   5
   6 There are broken devices in the wild that handle duplicate IP address
   7 detection by sending out ARP requests for the IP that they received from a
   8 DHCP server and refuse the address if they get a reply.
   9 When proxyarp is enabled, they would go into a loop of requesting an address
  10 and then NAKing it again.
  11
  12 Link: https://github.com/openwrt/openwrt/issues/14309
  13 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  14 ---
  15
  16 --- a/net/bridge/br_arp_nd_proxy.c
  17 +++ b/net/bridge/br_arp_nd_proxy.c
  18 @@ -204,7 +204,10 @@ void br_do_proxy_suppress_arp(struct sk_
  19                         if ((p && (p->flags & BR_PROXYARP)) ||
  20                             (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
  21                                                          BR_NEIGH_SUPPRESS)))) {
  22 -                               if (!vid)
  23 +                               replied = true;
  24 +                               if (!memcmp(n->ha, sha, dev->addr_len))
  25 +                                       replied = false;
  26 +                               else if (!vid)
  27                                         br_arp_send(br, p, skb->dev, sip, tip,
  28                                                     sha, n->ha, sha, 0, 0);
  29                                 else
  30 @@ -212,7 +215,6 @@ void br_do_proxy_suppress_arp(struct sk_
  31                                                     sha, n->ha, sha,
  32                                                     skb->vlan_proto,
  33                                                     skb_vlan_tag_get(skb));
  34 -                               replied = true;
  35                         }
  36
  37                         /* If we have replied or as long as we know the