diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index f6e37c4..8b833dd 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -3799,6 +3799,15 @@
  * @gfp: context flags
  */
 void cfg80211_ap_stopped(struct net_device *netdev, gfp_t gfp);
+/**
+ * cfg80211_is_gratuitous_arp_unsolicited_na - packet is grat. ARP/unsol. NA
+ * @skb: the input packet, must be an ethernet frame already
+ *
+ * Return: %true if the packet is a gratuitous ARP or unsolicited NA packet.
+ * This is used to drop packets that shouldn't occur because the AP implements
+ * a proxy service.
+ */
+bool cfg80211_is_gratuitous_arp_unsolicited_na(struct sk_buff *skb);
 
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
 
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 1ba7232..b83c5b2 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -10,6 +10,8 @@
 #include <net/cfg80211.h>
 #include <net/ip.h>
 #include <net/dsfield.h>
+#include <net/ndisc.h>
+#include <linux/if_arp.h>
 #include "core.h"
 
 struct ieee80211_rate *
@@ -1150,3 +1152,54 @@
 const unsigned char bridge_tunnel_header[] __aligned(2) =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
 EXPORT_SYMBOL(bridge_tunnel_header);
+
+bool cfg80211_is_gratuitous_arp_unsolicited_na(struct sk_buff *skb)
+{
+	const struct ethhdr *eth = (void *)skb->data;
+	const struct {
+		struct arphdr hdr;
+		u8 ar_sha[ETH_ALEN];
+		u8 ar_sip[4];
+		u8 ar_tha[ETH_ALEN];
+		u8 ar_tip[4];
+	} __packed *arp;
+	const struct ipv6hdr *ipv6;
+	const struct icmp6hdr *icmpv6;
+
+	switch (eth->h_proto) {
+	case cpu_to_be16(ETH_P_ARP):
+		/* can't say - but will probably be dropped later anyway */
+		if (!pskb_may_pull(skb, sizeof(*eth) + sizeof(*arp)))
+			return false;
+
+		arp = (void *)(eth + 1);
+
+		if ((arp->hdr.ar_op == cpu_to_be16(ARPOP_REPLY) ||
+		     arp->hdr.ar_op == cpu_to_be16(ARPOP_REQUEST)) &&
+		    !memcmp(arp->ar_sip, arp->ar_tip, sizeof(arp->ar_sip)))
+			return true;
+		break;
+	case cpu_to_be16(ETH_P_IPV6):
+		/* can't say - but will probably be dropped later anyway */
+		if (!pskb_may_pull(skb, sizeof(*eth) + sizeof(*ipv6) +
+					sizeof(*icmpv6)))
+			return false;
+
+		ipv6 = (void *)(eth + 1);
+		icmpv6 = (void *)(ipv6 + 1);
+
+		if (icmpv6->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
+		    !memcmp(&ipv6->saddr, &ipv6->daddr, sizeof(ipv6->saddr)))
+			return true;
+		break;
+	default:
+		/*
+		 * no need to support other protocols, proxy service isn't
+		 * specified for any others
+		 */
+		break;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(cfg80211_is_gratuitous_arp_unsolicited_na);