bluetooth: msft: Handle MSFT Monitor Device Event

Whenever the controller starts/stops monitoring a bt device, it sends
MSFT Monitor Device event. Add handler to read this vendor event.

Test performed:
- Verified by logs that the MSFT Monitor Device event is received from
  the controller whenever it starts/stops monitoring a device.

Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Miao-chen Chou <mcchou@google.com>

include/net/bluetooth/hci_core.h

@@ -258,6 +258,15 @@ struct adv_info {
 
 #define HCI_ADV_TX_POWER_NO_PREFERENCE 0x7F
 
+struct monitored_device {
+	struct list_head list;
+
+	bdaddr_t bdaddr;
+	__u8     addr_type;
+	__u16    handle;
+	bool     notified;
+};
+
 struct adv_pattern {
 	struct list_head list;
 	__u8 ad_type;
@@ -590,6 +599,8 @@ struct hci_dev {
 
 	struct delayed_work	interleave_scan;
 
+	struct list_head	monitored_devices;
+
 #if IS_ENABLED(CONFIG_BT_LEDS)
 	struct led_trigger	*power_led;
 #endif

net/bluetooth/hci_core.c

@@ -2503,6 +2503,7 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
 	INIT_LIST_HEAD(&hdev->conn_hash.list);
 	INIT_LIST_HEAD(&hdev->adv_instances);
 	INIT_LIST_HEAD(&hdev->blocked_keys);
+	INIT_LIST_HEAD(&hdev->monitored_devices);
 
 	INIT_LIST_HEAD(&hdev->local_codecs);
 	INIT_WORK(&hdev->rx_work, hci_rx_work);

net/bluetooth/msft.c

@@ -80,6 +80,14 @@ struct msft_rp_le_set_advertisement_filter_enable {
 	__u8 sub_opcode;
 } __packed;
 
+#define MSFT_EV_LE_MONITOR_DEVICE	0x02
+struct msft_ev_le_monitor_device {
+	__u8     addr_type;
+	bdaddr_t bdaddr;
+	__u8     monitor_handle;
+	__u8     monitor_state;
+} __packed;
+
 struct msft_monitor_advertisement_handle_data {
 	__u8  msft_handle;
 	__u16 mgmt_handle;
@@ -294,6 +302,15 @@ static void msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 		if (monitor && !msft->suspending)
 			hci_free_adv_monitor(hdev, monitor);
 
+		/* Clear any monitored devices by this Adv Monitor */
+		list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices,
+					 list) {
+			if (dev->handle == handle_data->mgmt_handle) {
+				list_del(&dev->list);
+				kfree(dev);
+			}
+		}
+
 		list_del(&handle_data->list);
 		kfree(handle_data);
 	}
@@ -538,6 +555,7 @@ void msft_do_close(struct hci_dev *hdev)
 	struct msft_data *msft = hdev->msft_data;
 	struct msft_monitor_advertisement_handle_data *handle_data, *tmp;
 	struct adv_monitor *monitor;
+	struct monitored_device *dev, *tmp_dev;
 
 	if (!msft)
 		return;
@@ -557,6 +575,16 @@ void msft_do_close(struct hci_dev *hdev)
 		list_del(&handle_data->list);
 		kfree(handle_data);
 	}
+
+	hci_dev_lock(hdev);
+
+	/* Clear any devices that are being monitored */
+	list_for_each_entry_safe(dev, tmp_dev, &hdev->monitored_devices, list) {
+		list_del(&dev->list);
+		kfree(dev);
+	}
+
+	hci_dev_unlock(hdev);
 }
 
 void msft_register(struct hci_dev *hdev)
@@ -590,10 +618,103 @@ void msft_unregister(struct hci_dev *hdev)
 	kfree(msft);
 }
 
+/* This function requires the caller holds hdev->lock */
+static void msft_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr,
+			      __u8 addr_type, __u16 mgmt_handle)
+{
+	struct monitored_device *dev;
+
+	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		bt_dev_err(hdev, "MSFT vendor event %u: no memory",
+			   MSFT_EV_LE_MONITOR_DEVICE);
+		return;
+	}
+
+	bacpy(&dev->bdaddr, bdaddr);
+	dev->addr_type = addr_type;
+	dev->handle = mgmt_handle;
+	dev->notified = false;
+
+	INIT_LIST_HEAD(&dev->list);
+	list_add(&dev->list, &hdev->monitored_devices);
+}
+
+/* This function requires the caller holds hdev->lock */
+static void msft_device_lost(struct hci_dev *hdev, bdaddr_t *bdaddr,
+			     __u8 addr_type, __u16 mgmt_handle)
+{
+	struct monitored_device *dev, *tmp;
+
+	list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices, list) {
+		if (dev->handle == mgmt_handle) {
+			list_del(&dev->list);
+			kfree(dev);
+
+			break;
+		}
+	}
+}
+
+static void *msft_skb_pull(struct hci_dev *hdev, struct sk_buff *skb,
+			   u8 ev, size_t len)
+{
+	void *data;
+
+	data = skb_pull_data(skb, len);
+	if (!data)
+		bt_dev_err(hdev, "Malformed MSFT vendor event: 0x%02x", ev);
+
+	return data;
+}
+
+/* This function requires the caller holds hdev->lock */
+static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct msft_ev_le_monitor_device *ev;
+	struct msft_monitor_advertisement_handle_data *handle_data;
+	u8 addr_type;
+
+	ev = msft_skb_pull(hdev, skb, MSFT_EV_LE_MONITOR_DEVICE, sizeof(*ev));
+	if (!ev)
+		return;
+
+	bt_dev_dbg(hdev,
+		   "MSFT vendor event 0x%02x: handle 0x%04x state %d addr %pMR",
+		   MSFT_EV_LE_MONITOR_DEVICE, ev->monitor_handle,
+		   ev->monitor_state, &ev->bdaddr);
+
+	handle_data = msft_find_handle_data(hdev, ev->monitor_handle, false);
+
+	switch (ev->addr_type) {
+	case ADDR_LE_DEV_PUBLIC:
+		addr_type = BDADDR_LE_PUBLIC;
+		break;
+
+	case ADDR_LE_DEV_RANDOM:
+		addr_type = BDADDR_LE_RANDOM;
+		break;
+
+	default:
+		bt_dev_err(hdev,
+			   "MSFT vendor event 0x%02x: unknown addr type 0x%02x",
+			   MSFT_EV_LE_MONITOR_DEVICE, ev->addr_type);
+		return;
+	}
+
+	if (ev->monitor_state)
+		msft_device_found(hdev, &ev->bdaddr, addr_type,
+				  handle_data->mgmt_handle);
+	else
+		msft_device_lost(hdev, &ev->bdaddr, addr_type,
+				 handle_data->mgmt_handle);
+}
+
 void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
 {
 	struct msft_data *msft = hdev->msft_data;
-	u8 event;
+	u8 *evt_prefix;
+	u8 *evt;
 
 	if (!msft)
 		return;
@@ -602,13 +723,12 @@ void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
 	 * matches, and otherwise just return.
 	 */
 	if (msft->evt_prefix_len > 0) {
-		if (skb->len < msft->evt_prefix_len)
+		evt_prefix = msft_skb_pull(hdev, skb, 0, msft->evt_prefix_len);
+		if (!evt_prefix)
 			return;
 
-		if (memcmp(skb->data, msft->evt_prefix, msft->evt_prefix_len))
+		if (memcmp(evt_prefix, msft->evt_prefix, msft->evt_prefix_len))
 			return;
-
-		skb_pull(skb, msft->evt_prefix_len);
 	}
 
 	/* Every event starts at least with an event code and the rest of
@@ -617,10 +737,23 @@ void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
 	if (skb->len < 1)
 		return;
 
-	event = *skb->data;
-	skb_pull(skb, 1);
+	hci_dev_lock(hdev);
+
+	evt = msft_skb_pull(hdev, skb, 0, sizeof(*evt));
+	if (!evt)
+		return;
+
+	switch (*evt) {
+	case MSFT_EV_LE_MONITOR_DEVICE:
+		msft_monitor_device_evt(hdev, skb);
+		break;
 
-	bt_dev_dbg(hdev, "MSFT vendor event %u", event);
+	default:
+		bt_dev_dbg(hdev, "MSFT vendor event 0x%02x", *evt);
+		break;
+	}
+
+	hci_dev_unlock(hdev);
 }
 
 __u64 msft_get_features(struct hci_dev *hdev)