Bluetooth: Add LE SC support for responding to Pairing Confirm PDU

When LE SC is being used we should always respond to it by sending our
local random number. This patch adds a convenience function for it which
also contains a check for the pre-requisite public key exchange
completion

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/smp.c

@@ -1216,6 +1216,25 @@ static u8 smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)
 	return 0;
 }
 
+static u8 sc_check_confirm(struct smp_chan *smp)
+{
+	struct l2cap_conn *conn = smp->conn;
+
+	BT_DBG("");
+
+	/* Public Key exchange must happen before any other steps */
+	if (!test_bit(SMP_FLAG_REMOTE_PK, &smp->flags))
+		return SMP_UNSPECIFIED;
+
+	if (conn->hcon->out) {
+		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
+			     smp->prnd);
+		SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
+	}
+
+	return 0;
+}
+
 static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb)
 {
 	struct l2cap_chan *chan = conn->smp;
@@ -1229,6 +1248,9 @@ static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb)
 	memcpy(smp->pcnf, skb->data, sizeof(smp->pcnf));
 	skb_pull(skb, sizeof(smp->pcnf));
 
+	if (test_bit(SMP_FLAG_SC, &smp->flags))
+		return sc_check_confirm(smp);
+
 	if (conn->hcon->out) {
 		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
 			     smp->prnd);