mac80211: drop non-auth 3-addr data frames when running as a 4-addr station

When running as a 4-addr station against an AP that has the 4-addr VLAN
interface and the main 3-addr AP interface bridged together, sometimes
frames originating from the station were looping back from the 3-addr AP
interface, causing the bridge code to emit warnings about receiving frames
with its own source address.
I'm not sure why this is happening yet, but I think it's a good idea to
drop all frames (except 802.1x/EAP frames) that do not match the configured
addressing mode, including 4-address frames sent to a 3-address station.
User test reports indicate that the problem goes away with this patch.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 22 insertions, 3 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index a6701ed87f0d..1236710f70e0 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1556,17 +1556,36 @@ __ieee80211_data_to_8023(struct ieee80211_rx_data *rx)
 {
         struct ieee80211_sub_if_data *sdata = rx->sdata;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
+        bool check_port_control = false;
+        struct ethhdr *ehdr;
+        int ret;
 
         if (ieee80211_has_a4(hdr->frame_control) &&
             sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->u.vlan.sta)
                 return -1;
 
+        if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+            !!sdata->u.mgd.use_4addr != !!ieee80211_has_a4(hdr->frame_control)) {
+
+                if (!sdata->u.mgd.use_4addr)
+                        return -1;
+                else
+                        check_port_control = true;
+        }
+
         if (is_multicast_ether_addr(hdr->addr1) &&
-            ((sdata->vif.type == NL80211_IFTYPE_AP_VLAN && sdata->u.vlan.sta) ||
-             (sdata->vif.type == NL80211_IFTYPE_STATION && sdata->u.mgd.use_4addr)))
+            sdata->vif.type == NL80211_IFTYPE_AP_VLAN && sdata->u.vlan.sta)
                 return -1;
 
-        return ieee80211_data_to_8023(rx->skb, sdata->vif.addr, sdata->vif.type);
+        ret = ieee80211_data_to_8023(rx->skb, sdata->vif.addr, sdata->vif.type);
+        if (ret < 0 || !check_port_control)
+                return ret;
+
+        ehdr = (struct ethhdr *) rx->skb->data;
+        if (ehdr->h_proto != rx->sdata->control_port_protocol)
+                return -1;
+
+        return 0;
 }
 
 /*