1 files changed, 25 insertions, 9 deletions

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 08419a2e6b95..68715783a742 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1814,7 +1814,7 @@ batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the frame to be checked
  * @vid: the VLAN ID of the frame
- * @is_bcast: the packet came in a broadcast packet type.
+ * @packet_type: the batman packet type this frame came in
  *
  * batadv_bla_rx avoidance checks if:
  *  * we have to race for a claim
@@ -1826,7 +1826,7 @@ batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
  * further process the skb.
  */
 bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
-		   unsigned short vid, bool is_bcast)
+		   unsigned short vid, int packet_type)
 {
 	struct batadv_bla_backbone_gw *backbone_gw;
 	struct ethhdr *ethhdr;
@@ -1848,9 +1848,24 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		goto handled;
 
 	if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
-		/* don't allow broadcasts while requests are in flight */
-		if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast)
-			goto handled;
+		/* don't allow multicast packets while requests are in flight */
+		if (is_multicast_ether_addr(ethhdr->h_dest))
+			/* Both broadcast flooding or multicast-via-unicasts
+			 * delivery might send to multiple backbone gateways
+			 * sharing the same LAN and therefore need to coordinate
+			 * which backbone gateway forwards into the LAN,
+			 * by claiming the payload source address.
+			 *
+			 * Broadcast flooding and multicast-via-unicasts
+			 * delivery use the following two batman packet types.
+			 * Note: explicitly exclude BATADV_UNICAST_4ADDR,
+			 * as the DHCP gateway feature will send explicitly
+			 * to only one BLA gateway, so the claiming process
+			 * should be avoided there.
+			 */
+			if (packet_type == BATADV_BCAST ||
+			    packet_type == BATADV_UNICAST)
+				goto handled;
 
 	ether_addr_copy(search_claim.addr, ethhdr->h_source);
 	search_claim.vid = vid;
@@ -1885,13 +1900,14 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		goto allow;
 	}
 
-	/* if it is a broadcast ... */
-	if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast) {
+	/* if it is a multicast ... */
+	if (is_multicast_ether_addr(ethhdr->h_dest) &&
+	    (packet_type == BATADV_BCAST || packet_type == BATADV_UNICAST)) {
 		/* ... drop it. the responsible gateway is in charge.
 		 *
-		 * We need to check is_bcast because with the gateway
+		 * We need to check packet type because with the gateway
 		 * feature, broadcasts (like DHCP requests) may be sent
-		 * using a unicast packet type.
+		 * using a unicast 4 address packet type. See comment above.
 		 */
 		goto handled;
 	} else {