mac80211: strictly check mesh address extension mode

Mesh forwarding path checks for address extension mode to fetch
appropriate proxied address and MPP address. Existing condition
that looks for 6 address format is not strict enough so that
frames with improper values are processed and invalid entries
are added into MPP table. Fix that by adding a stricter check before
processing the packet.

Per IEEE Std 802.11s-2011 spec. Table 7-6g1 lists address extension
mode 0x3 as reserved one. And also Table Table 9-13 does not specify
0x3 as valid address field.

Fixes: 9b395bc3 ("mac80211: verify that skb data is present")
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rx.c

@@ -2492,7 +2492,8 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 		if (is_multicast_ether_addr(hdr->addr1)) {
 			mpp_addr = hdr->addr3;
 			proxied_addr = mesh_hdr->eaddr1;
-		} else if (mesh_hdr->flags & MESH_FLAGS_AE_A5_A6) {
+		} else if ((mesh_hdr->flags & MESH_FLAGS_AE) ==
+			    MESH_FLAGS_AE_A5_A6) {
 			/* has_a4 already checked in ieee80211_rx_mesh_check */
 			mpp_addr = hdr->addr4;
 			proxied_addr = mesh_hdr->eaddr2;

net/wireless/util.c

@@ -454,6 +454,8 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
 	if (iftype == NL80211_IFTYPE_MESH_POINT)
 		skb_copy_bits(skb, hdrlen, &mesh_flags, 1);
 
+	mesh_flags &= MESH_FLAGS_AE;
+
 	switch (hdr->frame_control &
 		cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 	case cpu_to_le16(IEEE80211_FCTL_TODS):
@@ -469,9 +471,9 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
 			     iftype != NL80211_IFTYPE_STATION))
 			return -1;
 		if (iftype == NL80211_IFTYPE_MESH_POINT) {
-			if (mesh_flags & MESH_FLAGS_AE_A4)
+			if (mesh_flags == MESH_FLAGS_AE_A4)
 				return -1;
-			if (mesh_flags & MESH_FLAGS_AE_A5_A6) {
+			if (mesh_flags == MESH_FLAGS_AE_A5_A6) {
 				skb_copy_bits(skb, hdrlen +
 					offsetof(struct ieee80211s_hdr, eaddr1),
 					tmp.h_dest, 2 * ETH_ALEN);
@@ -487,9 +489,9 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
 		     ether_addr_equal(tmp.h_source, addr)))
 			return -1;
 		if (iftype == NL80211_IFTYPE_MESH_POINT) {
-			if (mesh_flags & MESH_FLAGS_AE_A5_A6)
+			if (mesh_flags == MESH_FLAGS_AE_A5_A6)
 				return -1;
-			if (mesh_flags & MESH_FLAGS_AE_A4)
+			if (mesh_flags == MESH_FLAGS_AE_A4)
 				skb_copy_bits(skb, hdrlen +
 					offsetof(struct ieee80211s_hdr, eaddr1),
 					tmp.h_source, ETH_ALEN);