Bluetooth: Add support for LE Start Encryption

This adds support for starting SMP Phase 2 Encryption, when the initial
SMP negotiation is successful. This adds the LE Start Encryption and LE
Long Term Key Request commands and related events.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/hci.h

@@ -745,6 +745,33 @@ struct hci_cp_le_conn_update {
 	__le16   max_ce_len;
 } __packed;
 
+#define HCI_OP_LE_START_ENC		0x2019
+struct hci_cp_le_start_enc {
+	__le16	handle;
+	__u8	rand[8];
+	__le16	ediv;
+	__u8	ltk[16];
+} __packed;
+
+#define HCI_OP_LE_LTK_REPLY		0x201a
+struct hci_cp_le_ltk_reply {
+	__le16	handle;
+	__u8	ltk[16];
+} __packed;
+struct hci_rp_le_ltk_reply {
+	__u8	status;
+	__le16	handle;
+} __packed;
+
+#define HCI_OP_LE_LTK_NEG_REPLY		0x201b
+struct hci_cp_le_ltk_neg_reply {
+	__le16	handle;
+} __packed;
+struct hci_rp_le_ltk_neg_reply {
+	__u8	status;
+	__le16	handle;
+} __packed;
+
 /* ---- HCI Events ---- */
 #define HCI_EV_INQUIRY_COMPLETE		0x01
 
@@ -1035,6 +1062,13 @@ struct hci_ev_le_conn_complete {
 	__u8     clk_accurancy;
 } __packed;
 
+#define HCI_EV_LE_LTK_REQ		0x05
+struct hci_ev_le_ltk_req {
+	__le16	handle;
+	__u8	random[8];
+	__le16	ediv;
+} __packed;
+
 /* Advertising report event types */
 #define ADV_IND		0x00
 #define ADV_DIRECT_IND	0x01

include/net/bluetooth/hci_core.h

@@ -249,6 +249,7 @@ struct hci_conn {
 	__u8		power_save;
 	__u16		disc_timeout;
 	unsigned long	pend;
+	__u8		ltk[16];
 
 	__u8		remote_cap;
 	__u8		remote_oob;
@@ -861,4 +862,9 @@ void hci_req_complete(struct hci_dev *hdev, __u16 cmd, int result);
 
 void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max,
 					u16 latency, u16 to_multiplier);
+void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __u8 rand[8],
+							__u8 ltk[16]);
+void hci_le_ltk_reply(struct hci_conn *conn, u8 ltk[16]);
+void hci_le_ltk_neg_reply(struct hci_conn *conn);
+
 #endif /* __HCI_CORE_H */

net/bluetooth/hci_conn.c

@@ -204,6 +204,55 @@ void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max,
 }
 EXPORT_SYMBOL(hci_le_conn_update);
 
+void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __u8 rand[8],
+							__u8 ltk[16])
+{
+	struct hci_dev *hdev = conn->hdev;
+	struct hci_cp_le_start_enc cp;
+
+	BT_DBG("%p", conn);
+
+	memset(&cp, 0, sizeof(cp));
+
+	cp.handle = cpu_to_le16(conn->handle);
+	memcpy(cp.ltk, ltk, sizeof(cp.ltk));
+	cp.ediv = ediv;
+	memcpy(cp.rand, rand, sizeof(rand));
+
+	hci_send_cmd(hdev, HCI_OP_LE_START_ENC, sizeof(cp), &cp);
+}
+EXPORT_SYMBOL(hci_le_start_enc);
+
+void hci_le_ltk_reply(struct hci_conn *conn, u8 ltk[16])
+{
+	struct hci_dev *hdev = conn->hdev;
+	struct hci_cp_le_ltk_reply cp;
+
+	BT_DBG("%p", conn);
+
+	memset(&cp, 0, sizeof(cp));
+
+	cp.handle = cpu_to_le16(conn->handle);
+	memcpy(cp.ltk, ltk, sizeof(ltk));
+
+	hci_send_cmd(hdev, HCI_OP_LE_LTK_REPLY, sizeof(cp), &cp);
+}
+EXPORT_SYMBOL(hci_le_ltk_reply);
+
+void hci_le_ltk_neg_reply(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+	struct hci_cp_le_ltk_neg_reply cp;
+
+	BT_DBG("%p", conn);
+
+	memset(&cp, 0, sizeof(cp));
+
+	cp.handle = cpu_to_le16(conn->handle);
+
+	hci_send_cmd(hdev, HCI_OP_LE_LTK_NEG_REPLY, sizeof(cp), &cp);
+}
+
 /* Device _must_ be locked */
 void hci_sco_setup(struct hci_conn *conn, __u8 status)
 {

net/bluetooth/hci_event.c

@@ -868,6 +868,30 @@ static void hci_cc_le_set_scan_enable(struct hci_dev *hdev,
 	hci_dev_unlock(hdev);
 }
 
+static void hci_cc_le_ltk_reply(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_rp_le_ltk_reply *rp = (void *) skb->data;
+
+	BT_DBG("%s status 0x%x", hdev->name, rp->status);
+
+	if (rp->status)
+		return;
+
+	hci_req_complete(hdev, HCI_OP_LE_LTK_REPLY, rp->status);
+}
+
+static void hci_cc_le_ltk_neg_reply(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_rp_le_ltk_neg_reply *rp = (void *) skb->data;
+
+	BT_DBG("%s status 0x%x", hdev->name, rp->status);
+
+	if (rp->status)
+		return;
+
+	hci_req_complete(hdev, HCI_OP_LE_LTK_NEG_REPLY, rp->status);
+}
+
 static inline void hci_cs_inquiry(struct hci_dev *hdev, __u8 status)
 {
 	BT_DBG("%s status 0x%x", hdev->name, status);
@@ -1248,6 +1272,11 @@ static void hci_cs_le_create_conn(struct hci_dev *hdev, __u8 status)
 	hci_dev_unlock(hdev);
 }
 
+static void hci_cs_le_start_enc(struct hci_dev *hdev, u8 status)
+{
+	BT_DBG("%s status 0x%x", hdev->name, status);
+}
+
 static inline void hci_inquiry_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	__u8 status = *((__u8 *) skb->data);
@@ -1856,6 +1885,14 @@ static inline void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *sk
 		hci_cc_le_set_scan_enable(hdev, skb);
 		break;
 
+	case HCI_OP_LE_LTK_REPLY:
+		hci_cc_le_ltk_reply(hdev, skb);
+		break;
+
+	case HCI_OP_LE_LTK_NEG_REPLY:
+		hci_cc_le_ltk_neg_reply(hdev, skb);
+		break;
+
 	default:
 		BT_DBG("%s opcode 0x%x", hdev->name, opcode);
 		break;
@@ -1934,6 +1971,10 @@ static inline void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_cs_le_create_conn(hdev, ev->status);
 		break;
 
+	case HCI_OP_LE_START_ENC:
+		hci_cs_le_start_enc(hdev, ev->status);
+		break;
+
 	default:
 		BT_DBG("%s opcode 0x%x", hdev->name, opcode);
 		break;
@@ -2745,6 +2786,28 @@ static inline void hci_le_adv_report_evt(struct hci_dev *hdev,
 	hci_dev_unlock(hdev);
 }
 
+static inline void hci_le_ltk_request_evt(struct hci_dev *hdev,
+						struct sk_buff *skb)
+{
+	struct hci_ev_le_ltk_req *ev = (void *) skb->data;
+	struct hci_cp_le_ltk_reply cp;
+	struct hci_conn *conn;
+
+	BT_DBG("%s handle %d", hdev->name, cpu_to_le16(ev->handle));
+
+	hci_dev_lock(hdev);
+
+	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(ev->handle));
+
+	memset(&cp, 0, sizeof(cp));
+	cp.handle = cpu_to_le16(conn->handle);
+	memcpy(cp.ltk, conn->ltk, sizeof(conn->ltk));
+
+	hci_send_cmd(hdev, HCI_OP_LE_LTK_REPLY, sizeof(cp), &cp);
+
+	hci_dev_unlock(hdev);
+}
+
 static inline void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct hci_ev_le_meta *le_ev = (void *) skb->data;
@@ -2760,6 +2823,10 @@ static inline void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_le_adv_report_evt(hdev, skb);
 		break;
 
+	case HCI_EV_LE_LTK_REQ:
+		hci_le_ltk_request_evt(hdev, skb);
+		break;
+
 	default:
 		break;
 	}

net/bluetooth/smp.c

@@ -277,13 +277,16 @@ static void smp_cmd_pairing_confirm(struct l2cap_conn *conn,
 
 static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 {
-	struct crypto_blkcipher *tfm = conn->hcon->hdev->tfm;
+	struct hci_conn *hcon = conn->hcon;
+	struct crypto_blkcipher *tfm = hcon->hdev->tfm;
 	int ret;
 	u8 key[16], res[16], random[16], confirm[16], buf[128];
 
 	swap128(skb->data, random);
 	skb_pull(skb, sizeof(random));
 
+	memset(hcon->ltk, 0, sizeof(hcon->ltk));
+
 	if (conn->hcon->out)
 		ret = smp_c1(tfm, conn->tk, random, conn->preq, conn->prsp, 0,
 				conn->src, conn->hcon->dst_type, conn->dst,
@@ -309,11 +312,15 @@ static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 	}
 
 	if (conn->hcon->out) {
+		__le16 ediv;
+		u8 rand[8];
+
 		smp_s1(tfm, conn->tk, random, conn->prnd, key);
+		swap128(key, hcon->ltk);
 
-		hex_dump_to_buffer(key, sizeof(key), 16, 1, buf,
-							sizeof(buf), 0);
-		BT_DBG("key %s", buf);
+		memset(rand, 0, sizeof(rand));
+		ediv = 0;
+		hci_le_start_enc(hcon, ediv, rand, hcon->ltk);
 	} else {
 		u8 r[16];
 
@@ -321,6 +328,7 @@ static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(r), r);
 
 		smp_s1(tfm, conn->tk, conn->prnd, random, key);
+		swap128(key, hcon->ltk);
 
 		hex_dump_to_buffer(key, sizeof(key), 16, 1, buf,
 							sizeof(buf), 0);