mac80211: fix use of skb->cb for mesh forwarding

Now we deal with mesh forwarding before the 802.11->802.3 conversion, thus
eliminating a few unnecessary steps. The next hop lookup is called from
ieee80211_master_start_xmit() instead of subif_start_xmit(). Until the next hop
is found, RA in the frame will be all zeroes for frames originating from the
device. For forwarded frames, RA will contain the TA of the received frame,
which will be necessary to send a path error if a next hop is not found.

Signed-off-by: Luis Carlos Cobo <[e-mail]>
Acked-by: Johannes Berg <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

net/mac80211/mesh.h

···
 void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata);
 
 /* Mesh paths */
-int mesh_nexthop_lookup(u8 *next_hop, struct sk_buff *skb,
-		struct net_device *dev);
+int mesh_nexthop_lookup(struct sk_buff *skb, struct net_device *dev);
 void mesh_path_start_discovery(struct net_device *dev);
 struct mesh_path *mesh_path_lookup(u8 *dst, struct net_device *dev);
 struct mesh_path *mesh_path_lookup_by_idx(int idx, struct net_device *dev);
···
 #else
 #define mesh_allocated	0
 #endif
-
-#define MESH_PREQ(skb)	(skb->cb + 30)
 
 #endif /* IEEE80211S_H */

net/mac80211/mesh_hwmp.c

···
 /**
  * ieee80211s_lookup_nexthop - put the appropriate next hop on a mesh frame
  *
- * @next_hop: output argument for next hop address
- * @skb: frame to be sent
+ * @skb: 802.11 frame to be sent
  * @dev: network device the frame will be sent through
+ * @fwd_frame: true if this frame was originally from a different host
  *
  * Returns: 0 if the next hop was found. Nonzero otherwise. If no next hop is
  * found, the function will start a path discovery and queue the frame so it is
  * sent when the path is resolved. This means the caller must not free the skb
  * in this case.
  */
-int mesh_nexthop_lookup(u8 *next_hop, struct sk_buff *skb,
-		struct net_device *dev)
+int mesh_nexthop_lookup(struct sk_buff *skb, struct net_device *dev)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct sk_buff *skb_to_free = NULL;
 	struct mesh_path *mpath;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	u8 *dst_addr = hdr->addr3;
 	int err = 0;
 
 	rcu_read_lock();
-	mpath = mesh_path_lookup(skb->data, dev);
+	mpath = mesh_path_lookup(dst_addr, dev);
 
 	if (!mpath) {
-		mesh_path_add(skb->data, dev);
-		mpath = mesh_path_lookup(skb->data, dev);
+		mesh_path_add(dst_addr, dev);
+		mpath = mesh_path_lookup(dst_addr, dev);
 		if (!mpath) {
 			dev_kfree_skb(skb);
 			sdata->u.sta.mshstats.dropped_frames_no_route++;
···
 	if (mpath->flags & MESH_PATH_ACTIVE) {
 		if (time_after(jiffies, mpath->exp_time -
 			msecs_to_jiffies(sdata->u.sta.mshcfg.path_refresh_time))
-				&& skb->pkt_type != PACKET_OTHERHOST
+				&& !memcmp(dev->dev_addr, hdr->addr4, ETH_ALEN)
 				&& !(mpath->flags & MESH_PATH_RESOLVING)
 				&& !(mpath->flags & MESH_PATH_FIXED)) {
 			mesh_queue_preq(mpath,
 					PREQ_Q_F_START | PREQ_Q_F_REFRESH);
 		}
-		memcpy(next_hop, mpath->next_hop->addr,
+		memcpy(hdr->addr1, mpath->next_hop->addr,
 				ETH_ALEN);
 	} else {
 		if (!(mpath->flags & MESH_PATH_RESOLVING)) {

net/mac80211/mesh_pathtbl.c

···
 void mesh_path_discard_frame(struct sk_buff *skb, struct net_device *dev)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	struct mesh_path *mpath;
 	u32 dsn = 0;
 
-	if (skb->pkt_type == PACKET_OTHERHOST) {
-		struct ieee80211s_hdr *prev_meshhdr;
-		int mshhdrlen;
+	if (memcmp(hdr->addr4, dev->dev_addr, ETH_ALEN) != 0) {
 		u8 *ra, *da;
 
-		prev_meshhdr = ((struct ieee80211s_hdr *)skb->cb);
-		mshhdrlen = ieee80211_get_mesh_hdrlen(prev_meshhdr);
-		da = skb->data;
-		ra = MESH_PREQ(skb);
+		da = hdr->addr3;
+		ra = hdr->addr2;
 		mpath = mesh_path_lookup(da, dev);
 		if (mpath)
 			dsn = ++mpath->dsn;

net/mac80211/rx.c

···
 
 	hdrlen = ieee80211_get_hdrlen(fc);
 
-	if (ieee80211_vif_is_mesh(&sdata->vif)) {
-		int meshhdrlen = ieee80211_get_mesh_hdrlen(
+	if (ieee80211_vif_is_mesh(&sdata->vif))
+		hdrlen += ieee80211_get_mesh_hdrlen(
 				(struct ieee80211s_hdr *) (skb->data + hdrlen));
-		/* Copy on cb:
-		 *  - mesh header: to be used for mesh forwarding
-		 * decision. It will also be used as mesh header template at
-		 * tx.c:ieee80211_subif_start_xmit() if interface
-		 * type is mesh and skb->pkt_type == PACKET_OTHERHOST
-		 *  - ta: to be used if a RERR needs to be sent.
-		 */
-		memcpy(skb->cb, skb->data + hdrlen, meshhdrlen);
-		memcpy(MESH_PREQ(skb), hdr->addr2, ETH_ALEN);
-		hdrlen += meshhdrlen;
-	}
 
 	/* convert IEEE 802.11 header + possible LLC headers into Ethernet
 	 * header
···
 		}
 	}
 
-	/* Mesh forwarding */
-	if (ieee80211_vif_is_mesh(&sdata->vif)) {
-		u8 *mesh_ttl = &((struct ieee80211s_hdr *)skb->cb)->ttl;
-		(*mesh_ttl)--;
-
-		if (is_multicast_ether_addr(skb->data)) {
-			if (*mesh_ttl > 0) {
-				xmit_skb = skb_copy(skb, GFP_ATOMIC);
-				if (xmit_skb)
-					xmit_skb->pkt_type = PACKET_OTHERHOST;
-				else if (net_ratelimit())
-					printk(KERN_DEBUG "%s: failed to clone "
-					       "multicast frame\n", dev->name);
-			} else
-				IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.sta,
-							     dropped_frames_ttl);
-		} else if (skb->pkt_type != PACKET_OTHERHOST &&
-			compare_ether_addr(dev->dev_addr, skb->data) != 0) {
-			if (*mesh_ttl == 0) {
-				IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.sta,
-							     dropped_frames_ttl);
-				dev_kfree_skb(skb);
-				skb = NULL;
-			} else {
-				xmit_skb = skb;
-				xmit_skb->pkt_type = PACKET_OTHERHOST;
-				if (!(dev->flags & IFF_PROMISC))
-					skb  = NULL;
-			}
-		}
-	}
-
 	if (skb) {
 		/* deliver to local stack */
 		skb->protocol = eth_type_trans(skb, dev);
···
 
 	return RX_QUEUED;
 }
+
+static ieee80211_rx_result debug_noinline
+ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_hdr *hdr;
+	struct ieee80211s_hdr *mesh_hdr;
+	unsigned int hdrlen;
+	struct sk_buff *skb = rx->skb, *fwd_skb;
+
+	hdr = (struct ieee80211_hdr *) skb->data;
+	hdrlen = ieee80211_hdrlen(hdr->frame_control);
+	mesh_hdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);
+
+	if (!ieee80211_is_data(hdr->frame_control))
+		return RX_CONTINUE;
+
+	if (!mesh_hdr->ttl)
+		/* illegal frame */
+		return RX_DROP_MONITOR;
+
+	if (compare_ether_addr(rx->dev->dev_addr, hdr->addr3) == 0)
+		return RX_CONTINUE;
+
+	mesh_hdr->ttl--;
+
+	if (rx->flags & IEEE80211_RX_RA_MATCH) {
+		if (!mesh_hdr->ttl)
+			IEEE80211_IFSTA_MESH_CTR_INC(&rx->sdata->u.sta,
+						     dropped_frames_ttl);
+		else {
+			struct ieee80211_hdr *fwd_hdr;
+			fwd_skb = skb_copy(skb, GFP_ATOMIC);
+
+			if (!fwd_skb && net_ratelimit())
+				printk(KERN_DEBUG "%s: failed to clone mesh frame\n",
+						   rx->dev->name);
+
+			fwd_hdr =  (struct ieee80211_hdr *) fwd_skb->data;
+			/*
+			 * Save TA to addr1 to send TA a path error if a
+			 * suitable next hop is not found
+			 */
+			memcpy(fwd_hdr->addr1, fwd_hdr->addr2, ETH_ALEN);
+			memcpy(fwd_hdr->addr2, rx->dev->dev_addr, ETH_ALEN);
+			fwd_skb->dev = rx->local->mdev;
+			fwd_skb->iif = rx->dev->ifindex;
+			dev_queue_xmit(fwd_skb);
+		}
+	}
+
+	if (is_multicast_ether_addr(hdr->addr3) ||
+	    rx->dev->flags & IFF_PROMISC)
+		return RX_CONTINUE;
+	else
+		return RX_DROP_MONITOR;
+}
+
 
 static ieee80211_rx_result debug_noinline
 ieee80211_rx_h_data(struct ieee80211_rx_data *rx)
···
 	rx->sdata = sdata;
 	rx->dev = sdata->dev;
 
-#define CALL_RXH(rxh)		\
-	res = rxh(rx);		\
-	if (res != RX_CONTINUE)	\
-		goto rxh_done;
+#define CALL_RXH(rxh)			\
+	do {				\
+		res = rxh(rx);		\
+		if (res != RX_CONTINUE)	\
+			goto rxh_done;  \
+	} while (0);
 
 	CALL_RXH(ieee80211_rx_h_passive_scan)
 	CALL_RXH(ieee80211_rx_h_check)
···
 	/* must be after MMIC verify so header is counted in MPDU mic */
 	CALL_RXH(ieee80211_rx_h_remove_qos_control)
 	CALL_RXH(ieee80211_rx_h_amsdu)
+	if (ieee80211_vif_is_mesh(&sdata->vif))
+		CALL_RXH(ieee80211_rx_h_mesh_fwding);
 	CALL_RXH(ieee80211_rx_h_data)
 	CALL_RXH(ieee80211_rx_h_ctrl)
 	CALL_RXH(ieee80211_rx_h_mgmt)

net/mac80211/tx.c

···
 				struct net_device *dev)
 {
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	struct net_device *odev = NULL;
 	struct ieee80211_sub_if_data *osdata;
 	int headroom;
···
 	info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
 
 	osdata = IEEE80211_DEV_TO_SUB_IF(odev);
+
+	if (ieee80211_vif_is_mesh(&osdata->vif) &&
+	    ieee80211_is_data(hdr->frame_control)) {
+		if (ieee80211_is_data(hdr->frame_control)) {
+			if (is_multicast_ether_addr(hdr->addr3))
+				memcpy(hdr->addr1, hdr->addr3, ETH_ALEN);
+			else
+				if (mesh_nexthop_lookup(skb, odev))
+					return  0;
+			if (memcmp(odev->dev_addr, hdr->addr4, ETH_ALEN) != 0)
+				IEEE80211_IFSTA_MESH_CTR_INC(&osdata->u.sta,
+							     fwded_frames);
+		}
+	}
 
 	may_encrypt = !skb->do_not_encrypt;
 
···
 	case IEEE80211_IF_TYPE_MESH_POINT:
 		fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
 		/* RA TA DA SA */
-		if (is_multicast_ether_addr(skb->data))
-			memcpy(hdr.addr1, skb->data, ETH_ALEN);
-		else if (mesh_nexthop_lookup(hdr.addr1, skb, dev))
-				return 0;
+		memset(hdr.addr1, 0, ETH_ALEN);
 		memcpy(hdr.addr2, dev->dev_addr, ETH_ALEN);
 		memcpy(hdr.addr3, skb->data, ETH_ALEN);
 		memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN);
-		if (skb->pkt_type == PACKET_OTHERHOST) {
-			/* Forwarded frame, keep mesh ttl and seqnum */
-			struct ieee80211s_hdr *prev_meshhdr;
-			prev_meshhdr = ((struct ieee80211s_hdr *)skb->cb);
-			meshhdrlen = ieee80211_get_mesh_hdrlen(prev_meshhdr);
-			memcpy(&mesh_hdr, prev_meshhdr, meshhdrlen);
-			sdata->u.sta.mshstats.fwded_frames++;
-		} else {
-			if (!sdata->u.sta.mshcfg.dot11MeshTTL) {
-				/* Do not send frames with mesh_ttl == 0 */
-				sdata->u.sta.mshstats.dropped_frames_ttl++;
-				ret = 0;
-				goto fail;
-			}
-			meshhdrlen = ieee80211_new_mesh_header(&mesh_hdr,
-							       sdata);
+		if (!sdata->u.sta.mshcfg.dot11MeshTTL) {
+			/* Do not send frames with mesh_ttl == 0 */
+			sdata->u.sta.mshstats.dropped_frames_ttl++;
+			ret = 0;
+			goto fail;
 		}
+		meshhdrlen = ieee80211_new_mesh_header(&mesh_hdr, sdata);
 		hdrlen = 30;
 		break;
 #endif
···
 	 * Drop unicast frames to unauthorised stations unless they are
 	 * EAPOL frames from the local station.
 	 */
-	if (unlikely(!is_multicast_ether_addr(hdr.addr1) &&
+	if (!ieee80211_vif_is_mesh(&sdata->vif) &&
+		unlikely(!is_multicast_ether_addr(hdr.addr1) &&
 		      !(sta_flags & WLAN_STA_AUTHORIZED) &&
 		      !(ethertype == ETH_P_PAE &&
 		       compare_ether_addr(dev->dev_addr,