Bluetooth: Add simple SMP pairing negotiation

This implementation only exchanges SMP messages between the Host and the
Remote. No keys are being generated. TK and STK generation will be
provided in further patches.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/smp.h

@@ -38,6 +38,23 @@ struct smp_cmd_pairing {
 	__u8	resp_key_dist;
 } __packed;
 
+#define SMP_IO_DISPLAY_ONLY	0x00
+#define SMP_IO_DISPLAY_YESNO	0x01
+#define SMP_IO_KEYBOARD_ONLY	0x02
+#define SMP_IO_NO_INPUT_OUTPUT	0x03
+#define SMP_IO_KEYBOARD_DISPLAY	0x04
+
+#define SMP_OOB_NOT_PRESENT	0x00
+#define SMP_OOB_PRESENT		0x01
+
+#define SMP_DIST_ENC_KEY	0x01
+#define SMP_DIST_ID_KEY		0x02
+#define SMP_DIST_SIGN		0x04
+
+#define SMP_AUTH_NONE		0x00
+#define SMP_AUTH_BONDING	0x01
+#define SMP_AUTH_MITM		0x04
+
 #define SMP_CMD_PAIRING_CONFIRM	0x03
 struct smp_cmd_pairing_confirm {
 	__u8	confirm_val[16];

net/bluetooth/smp.c

@@ -64,6 +64,94 @@ static void smp_send_cmd(struct l2cap_conn *conn, u8 code, u16 len, void *data)
 	hci_send_acl(conn->hcon, skb, 0);
 }
 
+static void smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
+{
+	struct smp_cmd_pairing *rp = (void *) skb->data;
+
+	BT_DBG("conn %p", conn);
+
+	skb_pull(skb, sizeof(*rp));
+
+	rp->io_capability = 0x00;
+	rp->oob_flag = 0x00;
+	rp->max_key_size = 16;
+	rp->init_key_dist = 0x00;
+	rp->resp_key_dist = 0x00;
+	rp->auth_req &= (SMP_AUTH_BONDING | SMP_AUTH_MITM);
+
+	smp_send_cmd(conn, SMP_CMD_PAIRING_RSP, sizeof(*rp), rp);
+}
+
+static void smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)
+{
+	struct smp_cmd_pairing_confirm cp;
+
+	BT_DBG("conn %p", conn);
+
+	memset(&cp, 0, sizeof(cp));
+
+	smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cp), &cp);
+}
+
+static void smp_cmd_pairing_confirm(struct l2cap_conn *conn,
+							struct sk_buff *skb)
+{
+	BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");
+
+	if (conn->hcon->out) {
+		struct smp_cmd_pairing_random random;
+
+		memset(&random, 0, sizeof(random));
+
+		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(random),
+								&random);
+	} else {
+		struct smp_cmd_pairing_confirm confirm;
+
+		memset(&confirm, 0, sizeof(confirm));
+
+		smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(confirm),
+								&confirm);
+	}
+}
+
+static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
+{
+	struct smp_cmd_pairing_random cp;
+
+	BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");
+
+	skb_pull(skb, sizeof(cp));
+
+	if (conn->hcon->out) {
+		/* FIXME: start encryption */
+	} else {
+		memset(&cp, 0, sizeof(cp));
+
+		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(cp), &cp);
+	}
+}
+
+static void smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
+{
+	struct smp_cmd_security_req *rp = (void *) skb->data;
+	struct smp_cmd_pairing cp;
+
+	BT_DBG("conn %p", conn);
+
+	skb_pull(skb, sizeof(*rp));
+	memset(&cp, 0, sizeof(cp));
+
+	cp.io_capability = 0x00;
+	cp.oob_flag = 0x00;
+	cp.max_key_size = 16;
+	cp.init_key_dist = 0x00;
+	cp.resp_key_dist = 0x00;
+	cp.auth_req = rp->auth_req & (SMP_AUTH_BONDING | SMP_AUTH_MITM);
+
+	smp_send_cmd(conn, SMP_CMD_PAIRING_REQ, sizeof(cp), &cp);
+}
+
 int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level)
 {
 	__u8 authreq;
@@ -114,24 +202,33 @@ int smp_sig_channel(struct l2cap_conn *conn, struct sk_buff *skb)
 
 	switch (code) {
 	case SMP_CMD_PAIRING_REQ:
-		reason = SMP_PAIRING_NOTSUPP;
-		smp_send_cmd(conn, SMP_CMD_PAIRING_FAIL, sizeof(reason),
-								&reason);
-		err = -EOPNOTSUPP;
+		smp_cmd_pairing_req(conn, skb);
 		break;
 
 	case SMP_CMD_PAIRING_FAIL:
 		break;
 
 	case SMP_CMD_PAIRING_RSP:
+		smp_cmd_pairing_rsp(conn, skb);
+		break;
+
+	case SMP_CMD_SECURITY_REQ:
+		smp_cmd_security_req(conn, skb);
+		break;
+
 	case SMP_CMD_PAIRING_CONFIRM:
+		smp_cmd_pairing_confirm(conn, skb);
+		break;
+
 	case SMP_CMD_PAIRING_RANDOM:
+		smp_cmd_pairing_random(conn, skb);
+		break;
+
 	case SMP_CMD_ENCRYPT_INFO:
 	case SMP_CMD_MASTER_IDENT:
 	case SMP_CMD_IDENT_INFO:
 	case SMP_CMD_IDENT_ADDR_INFO:
 	case SMP_CMD_SIGN_INFO:
-	case SMP_CMD_SECURITY_REQ:
 	default:
 		BT_DBG("Unknown command code 0x%2.2x", code);