[Bluetooth] Add function for triggering a link key change

This patch adds the hci_conn_change_link_key() function that allows
to trigger a link key change for an existing connection.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -366,6 +366,11 @@ struct hci_cp_set_conn_encrypt {
 	__u8     encrypt;
 } __attribute__ ((packed));
 
+#define OCF_CHANGE_CONN_LINK_KEY 0x0015
+struct hci_cp_change_conn_link_key {
+	__u16    handle;
+} __attribute__ ((packed));
+
 #define OCF_READ_REMOTE_FEATURES 0x001B
 struct hci_cp_read_rmt_features {
 	__u16    handle;
@@ -482,6 +487,12 @@ struct hci_ev_encrypt_change {
 	__u8     encrypt;
 } __attribute__ ((packed));
 
+#define HCI_EV_CHANGE_CONN_LINK_KEY_COMPLETE	0x09
+struct hci_ev_change_conn_link_key_complete {
+	__u8     status;
+	__u16    handle;
+} __attribute__ ((packed));
+
 #define HCI_EV_QOS_SETUP_COMPLETE	0x0D
 struct hci_qos {
 	__u8     service_type;
@@ -522,6 +533,14 @@ struct hci_ev_role_change {
 	__u8     role;
 } __attribute__ ((packed));
 
+#define HCI_EV_MODE_CHANGE	0x14
+struct hci_ev_mode_change {
+	__u8     status;
+	__u16    handle;
+	__u8     mode;
+	__u16    interval;
+} __attribute__ ((packed));
+
 #define HCI_EV_PIN_CODE_REQ	0x16
 struct hci_ev_pin_code_req {
 	bdaddr_t bdaddr;

include/net/bluetooth/hci_core.h

@@ -277,6 +277,7 @@ void   hci_conn_hash_flush(struct hci_dev *hdev);
 struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *src);
 int hci_conn_auth(struct hci_conn *conn);
 int hci_conn_encrypt(struct hci_conn *conn);
+int hci_conn_change_link_key(struct hci_conn *conn);
 
 static inline void hci_conn_set_timer(struct hci_conn *conn, unsigned long timeout)
 {

net/bluetooth/hci_conn.c

@@ -333,6 +333,20 @@ int hci_conn_encrypt(struct hci_conn *conn)
 }
 EXPORT_SYMBOL(hci_conn_encrypt);
 
+/* Change link key */
+int hci_conn_change_link_key(struct hci_conn *conn)
+{
+	BT_DBG("conn %p", conn);
+
+	if (!test_and_set_bit(HCI_CONN_AUTH_PEND, &conn->pend)) {
+		struct hci_cp_change_conn_link_key cp;
+		cp.handle = __cpu_to_le16(conn->handle);
+		hci_send_cmd(conn->hdev, OGF_LINK_CTL, OCF_CHANGE_CONN_LINK_KEY, sizeof(cp), &cp);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(hci_conn_change_link_key);
+
 /* Drop all connection on the device */
 void hci_conn_hash_flush(struct hci_dev *hdev)
 {

net/bluetooth/hci_event.c

@@ -786,6 +786,11 @@ static inline void hci_encrypt_change_evt(struct hci_dev *hdev, struct sk_buff *
 	hci_dev_unlock(hdev);
 }
 
+/* Change Connection Link Key Complete */
+static inline void hci_change_conn_link_key_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
+{
+}
+
 /* Pin Code Request*/
 static inline void hci_pin_code_request_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
@@ -853,6 +858,10 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_encrypt_change_evt(hdev, skb);
 		break;
 
+	case HCI_EV_CHANGE_CONN_LINK_KEY_COMPLETE:
+		hci_change_conn_link_key_complete_evt(hdev, skb);
+		break;
+
 	case HCI_EV_PIN_CODE_REQ:
 		hci_pin_code_request_evt(hdev, skb);
 		break;