mac802154: Handle received BEACON_REQ

When performing an active scan, devices emit BEACON_REQ which
must be answered by other PANs receiving the request, unless they are
already passively sending beacons.

Answering a beacon request becomes a duty when the user tells us to send
beacons and the request provides an interval of 15.

Signed-off-by: Miquel Raynal <[e-mail]>
Acked-by: Alexander Aring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Stefan Schmidt <[e-mail]>

include/net/ieee802154_netdev.h

···
 			   struct ieee802154_beacon_frame *beacon);
 int ieee802154_mac_cmd_push(struct sk_buff *skb, void *frame,
 			    const void *pl, unsigned int pl_len);
+int ieee802154_mac_cmd_pl_pull(struct sk_buff *skb,
+			       struct ieee802154_mac_cmd_pl *mac_pl);
 
 int ieee802154_max_payload(const struct ieee802154_hdr *hdr);
 

net/ieee802154/header_ops.c

···
 }
 EXPORT_SYMBOL_GPL(ieee802154_hdr_pull);
 
+int ieee802154_mac_cmd_pl_pull(struct sk_buff *skb,
+			       struct ieee802154_mac_cmd_pl *mac_pl)
+{
+	if (!pskb_may_pull(skb, sizeof(*mac_pl)))
+		return -EINVAL;
+
+	memcpy(mac_pl, skb->data, sizeof(*mac_pl));
+	skb_pull(skb, sizeof(*mac_pl));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ieee802154_mac_cmd_pl_pull);
+
 int
 ieee802154_hdr_peek_addrs(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
 {

net/mac802154/ieee802154_i.h

···
 	/* Asynchronous tasks */
 	struct list_head rx_beacon_list;
 	struct work_struct rx_beacon_work;
+	struct list_head rx_mac_cmd_list;
+	struct work_struct rx_mac_cmd_work;
 
 	bool started;
 	bool suspended;
···
 ieee802154_sdata_running(struct ieee802154_sub_if_data *sdata)
 {
 	return test_bit(SDATA_STATE_RUNNING, &sdata->state);
+}
+
+static inline int ieee802154_get_mac_cmd(struct sk_buff *skb, u8 *mac_cmd)
+{
+	struct ieee802154_mac_cmd_pl mac_pl;
+	int ret;
+
+	if (mac_cb(skb)->type != IEEE802154_FC_TYPE_MAC_CMD)
+		return -EINVAL;
+
+	ret = ieee802154_mac_cmd_pl_pull(skb, &mac_pl);
+	if (ret)
+		return ret;
+
+	*mac_cmd = mac_pl.cmd_id;
+	return 0;
 }
 
 extern struct ieee802154_mlme_ops mac802154_mlme_wpan;
···
 {
 	return test_bit(IEEE802154_IS_BEACONING, &local->ongoing);
 }
+
+void mac802154_rx_mac_cmd_worker(struct work_struct *work);
 
 /* interface handling */
 int ieee802154_iface_init(void);

net/mac802154/main.c

···
 
 	INIT_LIST_HEAD(&local->interfaces);
 	INIT_LIST_HEAD(&local->rx_beacon_list);
+	INIT_LIST_HEAD(&local->rx_mac_cmd_list);
 	mutex_init(&local->iflist_mtx);
 
 	tasklet_setup(&local->tasklet, ieee802154_tasklet_handler);
···
 	INIT_DELAYED_WORK(&local->scan_work, mac802154_scan_worker);
 	INIT_WORK(&local->rx_beacon_work, mac802154_rx_beacon_worker);
 	INIT_DELAYED_WORK(&local->beacon_work, mac802154_beacon_worker);
+	INIT_WORK(&local->rx_mac_cmd_work, mac802154_rx_mac_cmd_worker);
 
 	/* init supported flags with 802.15.4 default ranges */
 	phy->supported.max_minbe = 8;

net/mac802154/rx.c

···
 	kfree(mac_pkt);
 }
 
+static bool mac802154_should_answer_beacon_req(struct ieee802154_local *local)
+{
+	struct cfg802154_beacon_request *beacon_req;
+	unsigned int interval;
+
+	rcu_read_lock();
+	beacon_req = rcu_dereference(local->beacon_req);
+	if (!beacon_req) {
+		rcu_read_unlock();
+		return false;
+	}
+
+	interval = beacon_req->interval;
+	rcu_read_unlock();
+
+	if (!mac802154_is_beaconing(local))
+		return false;
+
+	return interval == IEEE802154_ACTIVE_SCAN_DURATION;
+}
+
+void mac802154_rx_mac_cmd_worker(struct work_struct *work)
+{
+	struct ieee802154_local *local =
+		container_of(work, struct ieee802154_local, rx_mac_cmd_work);
+	struct cfg802154_mac_pkt *mac_pkt;
+	u8 mac_cmd;
+	int rc;
+
+	mac_pkt = list_first_entry_or_null(&local->rx_mac_cmd_list,
+					   struct cfg802154_mac_pkt, node);
+	if (!mac_pkt)
+		return;
+
+	rc = ieee802154_get_mac_cmd(mac_pkt->skb, &mac_cmd);
+	if (rc)
+		goto out;
+
+	switch (mac_cmd) {
+	case IEEE802154_CMD_BEACON_REQ:
+		dev_dbg(&mac_pkt->sdata->dev->dev, "processing BEACON REQ\n");
+		if (!mac802154_should_answer_beacon_req(local))
+			break;
+
+		queue_delayed_work(local->mac_wq, &local->beacon_work, 0);
+		break;
+	default:
+		break;
+	}
+
+out:
+	list_del(&mac_pkt->node);
+	kfree_skb(mac_pkt->skb);
+	kfree(mac_pkt);
+}
+
 static int
 ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
 		       struct sk_buff *skb, const struct ieee802154_hdr *hdr)
···
 		list_add_tail(&mac_pkt->node, &sdata->local->rx_beacon_list);
 		queue_work(sdata->local->mac_wq, &sdata->local->rx_beacon_work);
 		return NET_RX_SUCCESS;
-	case IEEE802154_FC_TYPE_ACK:
+
 	case IEEE802154_FC_TYPE_MAC_CMD:
+		dev_dbg(&sdata->dev->dev, "MAC COMMAND received\n");
+		mac_pkt = kzalloc(sizeof(*mac_pkt), GFP_ATOMIC);
+		if (!mac_pkt)
+			goto fail;
+
+		mac_pkt->skb = skb_get(skb);
+		mac_pkt->sdata = sdata;
+		list_add_tail(&mac_pkt->node, &sdata->local->rx_mac_cmd_list);
+		queue_work(sdata->local->mac_wq, &sdata->local->rx_mac_cmd_work);
+		return NET_RX_SUCCESS;
+
+	case IEEE802154_FC_TYPE_ACK:
 		goto fail;
 
 	case IEEE802154_FC_TYPE_DATA:

net/mac802154/scan.c

···
 	struct cfg802154_beacon_request *beacon_req;
 	struct ieee802154_sub_if_data *sdata;
 	struct wpan_dev *wpan_dev;
+	u8 interval;
 	int ret;
 
 	rcu_read_lock();
···
 	}
 
 	wpan_dev = beacon_req->wpan_dev;
+	interval = beacon_req->interval;
 
 	rcu_read_unlock();
 
···
 		dev_err(&sdata->dev->dev,
 			"Beacon could not be transmitted (%d)\n", ret);
 
-	queue_delayed_work(local->mac_wq, &local->beacon_work,
-			   local->beacon_interval);
+	if (interval < IEEE802154_ACTIVE_SCAN_DURATION)
+		queue_delayed_work(local->mac_wq, &local->beacon_work,
+				   local->beacon_interval);
 }
 
 int mac802154_stop_beacons_locked(struct ieee802154_local *local,
···
 	local->beacon.mhr.source.pan_id = request->wpan_dev->pan_id;
 	local->beacon.mhr.source.extended_addr = request->wpan_dev->extended_addr;
 	local->beacon.mac_pl.beacon_order = request->interval;
-	local->beacon.mac_pl.superframe_order = request->interval;
+	if (request->interval <= IEEE802154_MAX_SCAN_DURATION)
+		local->beacon.mac_pl.superframe_order = request->interval;
 	local->beacon.mac_pl.final_cap_slot = 0xf;
 	local->beacon.mac_pl.battery_life_ext = 0;
-	/* TODO: Fill this field depending on the coordinator capacity */
+	/* TODO: Fill this field with the coordinator situation in the network */
 	local->beacon.mac_pl.pan_coordinator = 1;
 	local->beacon.mac_pl.assoc_permit = 1;
+
+	if (request->interval == IEEE802154_ACTIVE_SCAN_DURATION)
+		return 0;
 
 	/* Start the beacon work */
 	local->beacon_interval =