Bluetooth: Fix SMP security elevation from medium to high

If we have an unauthenticated key it is not sufficient to acheive high
security. Therefore, when deciding whether to encrypt the link or
request pairing, it is essential to in addition to checking the
existence of a key to also check whether it is authenticated or not.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/smp.c

@@ -703,7 +703,7 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 	return 0;
 }
 
-static u8 smp_ltk_encrypt(struct l2cap_conn *conn)
+static u8 smp_ltk_encrypt(struct l2cap_conn *conn, u8 sec_level)
 {
 	struct smp_ltk *key;
 	struct hci_conn *hcon = conn->hcon;
@@ -712,6 +712,9 @@ static u8 smp_ltk_encrypt(struct l2cap_conn *conn)
 	if (!key)
 		return 0;
 
+	if (sec_level > BT_SECURITY_MEDIUM && !key->authenticated)
+		return 0;
+
 	if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
 		return 1;
 
@@ -732,7 +735,7 @@ static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
 
 	hcon->pending_sec_level = authreq_to_seclevel(rp->auth_req);
 
-	if (smp_ltk_encrypt(conn))
+	if (smp_ltk_encrypt(conn, hcon->pending_sec_level))
 		return 0;
 
 	if (test_and_set_bit(HCI_CONN_LE_SMP_PEND, &hcon->flags))
@@ -771,7 +774,7 @@ int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level)
 		return 1;
 
 	if (hcon->link_mode & HCI_LM_MASTER)
-		if (smp_ltk_encrypt(conn))
+		if (smp_ltk_encrypt(conn, sec_level))
 			goto done;
 
 	if (test_and_set_bit(HCI_CONN_LE_SMP_PEND, &hcon->flags))