[MAC80211]: filter locally-originated multicast frames

In STA mode, the AP will echo our traffic.  This includes multicast
traffic.

Receiving these frames confuses some protocols and applications,
notably IPv6 Duplicate Address Detection.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index e2c6f5cd1cf7..969be3adda7a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -988,9 +988,10 @@ ieee80211_rx_h_data(struct ieee80211_txrx_data *rx)
                 memcpy(dst, hdr->addr1, ETH_ALEN);
                 memcpy(src, hdr->addr3, ETH_ALEN);
 
-                if (sdata->type != IEEE80211_IF_TYPE_STA) {
+                if (sdata->type != IEEE80211_IF_TYPE_STA ||
+                    (is_multicast_ether_addr(dst) &&
+                     !compare_ether_addr(src, dev->dev_addr)))
                         return TXRX_DROP;
-                }
                 break;
         case 0:
                 /* DA SA BSSID */