mac80211: data path modification for TDLS peers

Mark the STA entries of enabled TDLS peers with a new "peer authorized"
flag.

During link setup, allow special TDLS setup frames through the AP, but
otherwise drop all packets destined to the peer. This is required by the
TDLS (802.11z) specification in order to prevent reordering of MSDUs
between the AP and direct paths.

When setup completes and the peer is authorized, send data directly,
bypassing the AP.

In the Rx path, allow data to be received directly from TDLS peers.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/cfg.c

@@ -2427,6 +2427,7 @@ static int ieee80211_tdls_mgmt(struct wiphy *wiphy, struct net_device *dev,
 static int ieee80211_tdls_oper(struct wiphy *wiphy, struct net_device *dev,
 			       u8 *peer, enum nl80211_tdls_operation oper)
 {
+	struct sta_info *sta;
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
 	if (!(wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS))
@@ -2441,6 +2442,15 @@ static int ieee80211_tdls_oper(struct wiphy *wiphy, struct net_device *dev,
 
 	switch (oper) {
 	case NL80211_TDLS_ENABLE_LINK:
+		rcu_read_lock();
+		sta = sta_info_get(sdata, peer);
+		if (!sta) {
+			rcu_read_unlock();
+			return -ENOLINK;
+		}
+
+		set_sta_flags(sta, WLAN_STA_TDLS_PEER_AUTH);
+		rcu_read_unlock();
 		break;
 	case NL80211_TDLS_DISABLE_LINK:
 		return sta_info_destroy_addr(sdata, peer);

net/mac80211/sta_info.h

@@ -45,7 +45,9 @@
  *	station in power-save mode, reply when the driver unblocks.
  * @WLAN_STA_PS_DRIVER_BUF: Station has frames pending in driver internal
  *	buffers. Automatically cleared on station wake-up.
- * @WLAN_STA_TDLS_PEER: station is a TDLS peer.
+ * @WLAN_STA_TDLS_PEER: Station is a TDLS peer.
+ * @WLAN_STA_TDLS_PEER_AUTH: This TDLS peer is authorized to send direct
+ *	packets. This means the link is enabled.
  */
 enum ieee80211_sta_info_flags {
 	WLAN_STA_AUTH		= 1<<0,
@@ -63,6 +65,7 @@ enum ieee80211_sta_info_flags {
 	WLAN_STA_PSPOLL		= 1<<13,
 	WLAN_STA_PS_DRIVER_BUF	= 1<<14,
 	WLAN_STA_TDLS_PEER	= 1<<15,
+	WLAN_STA_TDLS_PEER_AUTH	= 1<<16,
 };
 
 #define STA_TID_NUM 16

net/mac80211/tx.c

@@ -1726,6 +1726,7 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
 	struct sta_info *sta = NULL;
 	u32 sta_flags = 0;
 	struct sk_buff *tmp_skb;
+	bool tdls_direct = false;
 
 	if (unlikely(skb->len < ETH_HLEN)) {
 		ret = NETDEV_TX_OK;
@@ -1837,11 +1838,43 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
 		break;
 #endif
 	case NL80211_IFTYPE_STATION:
-		memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN);
-		if (sdata->u.mgd.use_4addr &&
+		if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) {
+			rcu_read_lock();
+			sta = sta_info_get(sdata, skb->data);
+			if (sta)
+				sta_flags = get_sta_flags(sta);
+			rcu_read_unlock();
+
+			/*
+			 * If the TDLS link is enabled, send everything
+			 * directly. Otherwise, allow TDLS setup frames
+			 * to be transmitted indirectly.
+			 */
+			tdls_direct =
+				(sta_flags & WLAN_STA_TDLS_PEER) &&
+				((sta_flags & WLAN_STA_TDLS_PEER_AUTH) ||
+				 !(ethertype == ETH_P_TDLS && skb->len > 14 &&
+				   skb->data[14] == WLAN_TDLS_SNAP_RFTYPE));
+		}
+
+		if (tdls_direct) {
+			/* link during setup - throw out frames to peer */
+			if (!(sta_flags & WLAN_STA_TDLS_PEER_AUTH)) {
+				ret = NETDEV_TX_OK;
+				goto fail;
+			}
+
+			/* DA SA BSSID */
+			memcpy(hdr.addr1, skb->data, ETH_ALEN);
+			memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
+			memcpy(hdr.addr3, sdata->u.mgd.bssid, ETH_ALEN);
+			hdrlen = 24;
+		}  else if (sdata->u.mgd.use_4addr &&
 			    cpu_to_be16(ethertype) != sdata->control_port_protocol) {
-			fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
+			fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS |
+					  IEEE80211_FCTL_TODS);
 			/* RA TA DA SA */
+			memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN);
 			memcpy(hdr.addr2, sdata->vif.addr, ETH_ALEN);
 			memcpy(hdr.addr3, skb->data, ETH_ALEN);
 			memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN);
@@ -1849,6 +1882,7 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
 		} else {
 			fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 			/* BSSID SA DA */
+			memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN);
 			memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 			memcpy(hdr.addr3, skb->data, ETH_ALEN);
 			hdrlen = 24;

net/wireless/util.c

@@ -396,7 +396,8 @@ int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
 		}
 		break;
 	case cpu_to_le16(0):
-		if (iftype != NL80211_IFTYPE_ADHOC)
+		if (iftype != NL80211_IFTYPE_ADHOC &&
+		    iftype != NL80211_IFTYPE_STATION)
 				return -1;
 		break;
 	}