mac80211: add support for the ADDBA extension element

HE allows peers to negotiate the aggregation fragmentation level to be used
during transmission. The level can be 1-3. The Ext element is added behind
the ADDBA request inside the action frame. The responder will then reply
with the same level or a lower one if the requested one is not supported.
This patch only handles the negotiation part as the ADDBA frames get passed
to the ATH11k firmware, which does the rest of the magic for us aswell as
generating the requests.

Signed-off-by: Shashidhar Lakkavalli <slakkavalli@datto.com>
Signed-off-by: John Crispin <john@phrozen.org>
Link: https://lore.kernel.org/r/20190729104512.27615-1-john@phrozen.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -981,6 +981,8 @@ struct ieee80211_mgmt {
 					__le16 capab;
 					__le16 timeout;
 					__le16 start_seq_num;
+					/* followed by BA Extension */
+					u8 variable[0];
 				} __packed addba_req;
 				struct{
 					u8 action_code;

net/mac80211/agg-rx.c

@@ -178,17 +178,52 @@ static void sta_rx_agg_reorder_timer_expired(struct timer_list *t)
 	rcu_read_unlock();
 }
 
-static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *da, u16 tid,
+static void ieee80211_add_addbaext(struct ieee80211_sub_if_data *sdata,
-				      u8 dialog_token, u16 status, u16 policy,
+				   struct sk_buff *skb,
-				      u16 buf_size, u16 timeout)
+				   const struct ieee80211_addba_ext_ie *req)
 {
+	struct ieee80211_supported_band *sband;
+	struct ieee80211_addba_ext_ie *resp;
+	const struct ieee80211_sta_he_cap *he_cap;
+	u8 frag_level, cap_frag_level;
+	u8 *pos;
+
+	sband = ieee80211_get_sband(sdata);
+	he_cap = ieee80211_get_he_iftype_cap(sband, sdata->vif.type);
+	if (!he_cap)
+		return;
+
+	pos = skb_put_zero(skb, 2 + sizeof(struct ieee80211_addba_ext_ie));
+	*pos++ = WLAN_EID_ADDBA_EXT;
+	*pos++ = sizeof(struct ieee80211_addba_ext_ie);
+	resp = (struct ieee80211_addba_ext_ie *)pos;
+	resp->data = req->data & IEEE80211_ADDBA_EXT_NO_FRAG;
+
+	frag_level = u32_get_bits(req->data,
+				  IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
+	cap_frag_level = u32_get_bits(he_cap->he_cap_elem.mac_cap_info[0],
+				      IEEE80211_HE_MAC_CAP0_DYNAMIC_FRAG_MASK);
+	if (frag_level > cap_frag_level)
+		frag_level = cap_frag_level;
+	resp->data |= u8_encode_bits(frag_level,
+				     IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
+}
+
+static void ieee80211_send_addba_resp(struct sta_info *sta, u8 *da, u16 tid,
+				      u8 dialog_token, u16 status, u16 policy,
+				      u16 buf_size, u16 timeout,
+				      const struct ieee80211_addba_ext_ie *addbaext)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
 	struct ieee80211_local *local = sdata->local;
 	struct sk_buff *skb;
 	struct ieee80211_mgmt *mgmt;
 	bool amsdu = ieee80211_hw_check(&local->hw, SUPPORTS_AMSDU_IN_AMPDU);
 	u16 capab;
 
-	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
+	skb = dev_alloc_skb(sizeof(*mgmt) +
+		    2 + sizeof(struct ieee80211_addba_ext_ie) +
+		    local->hw.extra_tx_headroom);
 	if (!skb)
 		return;
 
@@ -222,13 +257,17 @@ static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *d
 	mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
 	mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);
 
+	if (sta->sta.he_cap.has_he && addbaext)
+		ieee80211_add_addbaext(sdata, skb, addbaext);
+
 	ieee80211_tx_skb(sdata, skb);
 }
 
 void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
 				      u8 dialog_token, u16 timeout,
 				      u16 start_seq_num, u16 ba_policy, u16 tid,
-				      u16 buf_size, bool tx, bool auto_seq)
+				      u16 buf_size, bool tx, bool auto_seq,
+				      const struct ieee80211_addba_ext_ie *addbaext)
 {
 	struct ieee80211_local *local = sta->sdata->local;
 	struct tid_ampdu_rx *tid_agg_rx;
@@ -410,21 +449,22 @@ end:
 	}
 
 	if (tx)
-		ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
+		ieee80211_send_addba_resp(sta, sta->sta.addr, tid,
 					  dialog_token, status, 1, buf_size,
-					  timeout);
+					  timeout, addbaext);
 }
 
 static void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 					    u8 dialog_token, u16 timeout,
 					    u16 start_seq_num, u16 ba_policy,
 					    u16 tid, u16 buf_size, bool tx,
-					    bool auto_seq)
+					    bool auto_seq,
+					    const struct ieee80211_addba_ext_ie *addbaext)
 {
 	mutex_lock(&sta->ampdu_mlme.mtx);
 	___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
 					 start_seq_num, ba_policy, tid,
-					 buf_size, tx, auto_seq);
+					 buf_size, tx, auto_seq, addbaext);
 	mutex_unlock(&sta->ampdu_mlme.mtx);
 }
 
@@ -434,7 +474,9 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 				     size_t len)
 {
 	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num;
+	struct ieee802_11_elems elems = { 0 };
 	u8 dialog_token;
+	int ies_len;
 
 	/* extract session parameters from addba request frame */
 	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
@@ -447,9 +489,19 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
 	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
 
+	ies_len = len - offsetof(struct ieee80211_mgmt,
+				 u.action.u.addba_req.variable);
+	if (ies_len) {
+		ieee802_11_parse_elems(mgmt->u.action.u.addba_req.variable,
+                                ies_len, true, &elems, mgmt->bssid, NULL);
+		if (elems.parse_error)
+			return;
+	}
+
 	__ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
 					start_seq_num, ba_policy, tid,
-					buf_size, true, false);
+					buf_size, true, false,
+					elems.addba_ext_ie);
 }
 
 void ieee80211_manage_rx_ba_offl(struct ieee80211_vif *vif,

net/mac80211/ht.c

@@ -359,7 +359,7 @@ void ieee80211_ba_session_work(struct work_struct *work)
 				       sta->ampdu_mlme.tid_rx_manage_offl))
 			___ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid,
 							 IEEE80211_MAX_AMPDU_BUF_HT,
-							 false, true);
+							 false, true, NULL);
 
 		if (test_and_clear_bit(tid + IEEE80211_NUM_TIDS,
 				       sta->ampdu_mlme.tid_rx_manage_offl))

net/mac80211/ieee80211_i.h

@@ -1807,7 +1807,8 @@ void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
 				      u8 dialog_token, u16 timeout,
 				      u16 start_seq_num, u16 ba_policy, u16 tid,
-				      u16 buf_size, bool tx, bool auto_seq);
+				      u16 buf_size, bool tx, bool auto_seq,
+				      const struct ieee80211_addba_ext_ie *addbaext);
 void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
 					 enum ieee80211_agg_stop_reason reason);
 void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,