[Bluetooth] Track status of remote Simple Pairing mode

The Simple Pairing process can only be used if both sides have the
support enabled in the host stack. The current Bluetooth specification
has three ways to detect this support.

If an Extended Inquiry Result has been sent during inquiry then it
is safe to assume that Simple Pairing is enabled. It is not allowed
to enable Extended Inquiry without Simple Pairing. During the remote
name request phase a notification with the remote host supported
features will be sent to indicate Simple Pairing support. Also the
second page of the remote extended features can indicate support for
Simple Pairing.

For all three cases the value of remote Simple Pairing mode is stored
in the inquiry cache for later use.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -816,6 +816,12 @@ struct hci_ev_simple_pair_complete {
 	bdaddr_t bdaddr;
 } __attribute__ ((packed));
 
+#define HCI_EV_REMOTE_HOST_FEATURES	0x3d
+struct hci_ev_remote_host_features {
+	bdaddr_t bdaddr;
+	__u8     features[8];
+} __attribute__ ((packed));
+
 /* Internal events generated by Bluetooth stack */
 #define HCI_EV_STACK_INTERNAL	0xfd
 struct hci_ev_stack_internal {

include/net/bluetooth/hci_core.h

@@ -40,6 +40,7 @@ struct inquiry_data {
 	__u8		dev_class[3];
 	__le16		clock_offset;
 	__s8		rssi;
+	__u8		ssp_mode;
 };
 
 struct inquiry_entry {
@@ -162,6 +163,7 @@ struct hci_conn {
 	__u8		 attempt;
 	__u8		 dev_class[3];
 	__u8             features[8];
+	__u8             ssp_mode;
 	__u16            interval;
 	__u16            pkt_type;
 	__u16            link_policy;

net/bluetooth/hci_conn.c

@@ -71,12 +71,16 @@ void hci_acl_connect(struct hci_conn *conn)
 	bacpy(&cp.bdaddr, &conn->dst);
 	cp.pscan_rep_mode = 0x02;
 
-	if ((ie = hci_inquiry_cache_lookup(hdev, &conn->dst)) &&
-			inquiry_entry_age(ie) <= INQUIRY_ENTRY_AGE_MAX) {
+	if ((ie = hci_inquiry_cache_lookup(hdev, &conn->dst))) {
+		if (inquiry_entry_age(ie) <= INQUIRY_ENTRY_AGE_MAX) {
 			cp.pscan_rep_mode = ie->data.pscan_rep_mode;
 			cp.pscan_mode     = ie->data.pscan_mode;
-		cp.clock_offset   = ie->data.clock_offset | cpu_to_le16(0x8000);
+			cp.clock_offset   = ie->data.clock_offset |
+							cpu_to_le16(0x8000);
+		}
+
 		memcpy(conn->dev_class, ie->data.dev_class, 3);
+		conn->ssp_mode = ie->data.ssp_mode;
 	}
 
 	cp.pkt_type = cpu_to_le16(conn->pkt_type);

net/bluetooth/hci_event.c

@@ -736,6 +736,7 @@ static inline void hci_inquiry_result_evt(struct hci_dev *hdev, struct sk_buff *
 		memcpy(data.dev_class, info->dev_class, 3);
 		data.clock_offset	= info->clock_offset;
 		data.rssi		= 0x00;
+		data.ssp_mode		= 0x00;
 		info++;
 		hci_inquiry_cache_update(hdev, &data);
 	}
@@ -1390,6 +1391,7 @@ static inline void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev, struct
 			memcpy(data.dev_class, info->dev_class, 3);
 			data.clock_offset	= info->clock_offset;
 			data.rssi		= info->rssi;
+			data.ssp_mode		= 0x00;
 			info++;
 			hci_inquiry_cache_update(hdev, &data);
 		}
@@ -1404,6 +1406,7 @@ static inline void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev, struct
 			memcpy(data.dev_class, info->dev_class, 3);
 			data.clock_offset	= info->clock_offset;
 			data.rssi		= info->rssi;
+			data.ssp_mode		= 0x00;
 			info++;
 			hci_inquiry_cache_update(hdev, &data);
 		}
@@ -1414,7 +1417,27 @@ static inline void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev, struct
 
 static inline void hci_remote_ext_features_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
+	struct hci_ev_remote_ext_features *ev = (void *) skb->data;
+	struct hci_conn *conn;
+
 	BT_DBG("%s", hdev->name);
+
+	if (ev->status || ev->page != 0x01)
+		return;
+
+	hci_dev_lock(hdev);
+
+	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(ev->handle));
+	if (conn) {
+		struct inquiry_entry *ie;
+
+		if ((ie = hci_inquiry_cache_lookup(hdev, &conn->dst)))
+			ie->data.ssp_mode = (ev->features[0] & 0x01);
+
+		conn->ssp_mode = (ev->features[0] & 0x01);
+	}
+
+	hci_dev_unlock(hdev);
 }
 
 static inline void hci_sync_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
@@ -1494,6 +1517,7 @@ static inline void hci_extended_inquiry_result_evt(struct hci_dev *hdev, struct
 		memcpy(data.dev_class, info->dev_class, 3);
 		data.clock_offset       = info->clock_offset;
 		data.rssi               = info->rssi;
+		data.ssp_mode		= 0x01;
 		info++;
 		hci_inquiry_cache_update(hdev, &data);
 	}
@@ -1533,6 +1557,21 @@ static inline void hci_simple_pair_complete_evt(struct hci_dev *hdev, struct sk_
 	hci_dev_unlock(hdev);
 }
 
+static inline void hci_remote_host_features_evt(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_ev_remote_host_features *ev = (void *) skb->data;
+	struct inquiry_entry *ie;
+
+	BT_DBG("%s", hdev->name);
+
+	hci_dev_lock(hdev);
+
+	if ((ie = hci_inquiry_cache_lookup(hdev, &ev->bdaddr)))
+		ie->data.ssp_mode = (ev->features[0] & 0x01);
+
+	hci_dev_unlock(hdev);
+}
+
 void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct hci_event_hdr *hdr = (void *) skb->data;
@@ -1665,6 +1704,10 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_simple_pair_complete_evt(hdev, skb);
 		break;
 
+	case HCI_EV_REMOTE_HOST_FEATURES:
+		hci_remote_host_features_evt(hdev, skb);
+		break;
+
 	default:
 		BT_DBG("%s event 0x%x", hdev->name, event);
 		break;