mac80211: allow SA-QUERY processing in userspace

As discussed with Mathy almost two years ago in
http://lore.kernel.org/r/20180806224857.14853-1-Mathy.Vanhoef@cs.kuleuven.be
we should let userspace process SA-QUERY frames if it
wants to, so that it can handle OCV (operating channel
validation) which mac80211 doesn't know how to.

Evidently I had been expecting Mathy to (re)send such a
patch, but he never did, perhaps expecting me to do it
after our discussion.

In any case, this came up now with OCV getting more
attention, so move the code around as discussed there
to let userspace handle it, and do it properly.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20200526103131.1f9cf7e5b6db.Iae5b42b09ad2b1cbcbe13492002c43f0d1d51dfc@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rx.c

@@ -3354,19 +3354,6 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
 			}
 		}
 		break;
-	case WLAN_CATEGORY_SA_QUERY:
-		if (len < (IEEE80211_MIN_ACTION_SIZE +
-			   sizeof(mgmt->u.action.u.sa_query)))
-			break;
-
-		switch (mgmt->u.action.u.sa_query.action) {
-		case WLAN_ACTION_SA_QUERY_REQUEST:
-			if (sdata->vif.type != NL80211_IFTYPE_STATION)
-				break;
-			ieee80211_process_sa_query_req(sdata, mgmt, len);
-			goto handled;
-		}
-		break;
 	case WLAN_CATEGORY_SELF_PROTECTED:
 		if (len < (IEEE80211_MIN_ACTION_SIZE +
 			   sizeof(mgmt->u.action.u.self_prot.action_code)))
@@ -3456,6 +3443,41 @@ ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
 	return RX_CONTINUE;
 }
 
+static ieee80211_rx_result debug_noinline
+ieee80211_rx_h_action_post_userspace(struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_sub_if_data *sdata = rx->sdata;
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
+	int len = rx->skb->len;
+
+	if (!ieee80211_is_action(mgmt->frame_control))
+		return RX_CONTINUE;
+
+	switch (mgmt->u.action.category) {
+	case WLAN_CATEGORY_SA_QUERY:
+		if (len < (IEEE80211_MIN_ACTION_SIZE +
+			   sizeof(mgmt->u.action.u.sa_query)))
+			break;
+
+		switch (mgmt->u.action.u.sa_query.action) {
+		case WLAN_ACTION_SA_QUERY_REQUEST:
+			if (sdata->vif.type != NL80211_IFTYPE_STATION)
+				break;
+			ieee80211_process_sa_query_req(sdata, mgmt, len);
+			goto handled;
+		}
+		break;
+	}
+
+	return RX_CONTINUE;
+
+ handled:
+	if (rx->sta)
+		rx->sta->rx_stats.packets++;
+	dev_kfree_skb(rx->skb);
+	return RX_QUEUED;
+}
+
 static ieee80211_rx_result debug_noinline
 ieee80211_rx_h_action_return(struct ieee80211_rx_data *rx)
 {
@@ -3736,6 +3758,7 @@ static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx,
 		CALL_RXH(ieee80211_rx_h_mgmt_check);
 		CALL_RXH(ieee80211_rx_h_action);
 		CALL_RXH(ieee80211_rx_h_userspace_mgmt);
+		CALL_RXH(ieee80211_rx_h_action_post_userspace);
 		CALL_RXH(ieee80211_rx_h_action_return);
 		CALL_RXH(ieee80211_rx_h_mgmt);