bridge: Extend Proxy ARP design to allow optional rules for Wi-Fi

This extends the design in commit 958501163ddd ("bridge: Add support for
IEEE 802.11 Proxy ARP") with optional set of rules that are needed to
meet the IEEE 802.11 and Hotspot 2.0 requirements for ProxyARP. The
previously added BR_PROXYARP behavior is left as-is and a new
BR_PROXYARP_WIFI alternative is added so that this behavior can be
configured from user space when required.

In addition, this enables proxyarp functionality for unicast ARP
requests for both BR_PROXYARP and BR_PROXYARP_WIFI since it is possible
to use unicast as well as broadcast for these frames.

The key differences in functionality:

BR_PROXYARP:
- uses the flag on the bridge port on which the request frame was
  received to determine whether to reply
- block bridge port flooding completely on ports that enable proxy ARP

BR_PROXYARP_WIFI:
- uses the flag on the bridge port to which the target device of the
  request belongs
- block bridge port flooding selectively based on whether the proxyarp
  functionality replied

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 7 deletions

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index e2aa7be3a847..052c5ebbc947 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -60,7 +60,7 @@ static int br_pass_frame_up(struct sk_buff *skb)
 }
 
 static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
-			    u16 vid)
+			    u16 vid, struct net_bridge_port *p)
 {
 	struct net_device *dev = br->dev;
 	struct neighbour *n;
@@ -68,6 +68,8 @@ static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
 	u8 *arpptr, *sha;
 	__be32 sip, tip;
 
+	BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
+
 	if (dev->flags & IFF_NOARP)
 		return;
 
@@ -105,9 +107,12 @@ static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
 		}
 
 		f = __br_fdb_get(br, n->ha, vid);
-		if (f)
+		if (f && ((p->flags & BR_PROXYARP) ||
+			  (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
 			arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
 				 sha, n->ha, sha);
+			BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+		}
 
 		neigh_release(n);
 	}
@@ -153,12 +158,10 @@ int br_handle_frame_finish(struct sk_buff *skb)
 
 	dst = NULL;
 
-	if (is_broadcast_ether_addr(dest)) {
-		if (IS_ENABLED(CONFIG_INET) &&
-		    p->flags & BR_PROXYARP &&
-		    skb->protocol == htons(ETH_P_ARP))
-			br_do_proxy_arp(skb, br, vid);
+	if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
+		br_do_proxy_arp(skb, br, vid, p);
 
+	if (is_broadcast_ether_addr(dest)) {
 		skb2 = skb;
 		unicast = false;
 	} else if (is_multicast_ether_addr(dest)) {