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>

3 files changed, 52 insertions, 5 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 119a573af14b..bdf9852eec5b 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2427,6 +2427,7 @@ fail:
 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);
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index b6bd4e9d8722..c10e2e8632b5 100644
--- a/net/mac80211/sta_info.h
+++ b/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
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 542272acfc1a..0ca16880bbb4 100644
--- a/net/mac80211/tx.c
+++ b/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 &&
-                    cpu_to_be16(ethertype) != sdata->control_port_protocol) {
-                        fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
+                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);
                         /* 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;