Bluetooth: Add automated SSP user confirmation responses

This patch adds automated negative and positive (auto-accept) responses
for Secure Simple Pairing user confirmation requests. The responses are
only sent if the HCI_MGMT flag is set in order not to confuse older user
space versions (without management interface support).
Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/hci_event.c

@@ -2483,14 +2483,47 @@ static inline void hci_user_confirm_request_evt(struct hci_dev *hdev,
 							struct sk_buff *skb)
 {
 	struct hci_ev_user_confirm_req *ev = (void *) skb->data;
+	int loc_mitm, rem_mitm;
+	struct hci_conn *conn;
 
 	BT_DBG("%s", hdev->name);
 
 	hci_dev_lock(hdev);
 
-	if (test_bit(HCI_MGMT, &hdev->flags))
+	if (!test_bit(HCI_MGMT, &hdev->flags))
+		goto unlock;
+
+	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &ev->bdaddr);
+	if (!conn)
+		goto unlock;
+
+	loc_mitm = (conn->auth_type & 0x01);
+	rem_mitm = (conn->remote_auth & 0x01);
+
+	/* If we require MITM but the remote device can't provide that
+	 * (it has NoInputNoOutput) then reject the confirmation
+	 * request. The only exception is when we're dedicated bonding
+	 * initiators (connect_cfm_cb set) since then we always have the MITM
+	 * bit set. */
+	if (!conn->connect_cfm_cb && loc_mitm && conn->remote_cap == 0x03) {
+		BT_DBG("Rejecting request: remote device can't provide MITM");
+		hci_send_cmd(hdev, HCI_OP_USER_CONFIRM_NEG_REPLY,
+					sizeof(ev->bdaddr), &ev->bdaddr);
+		goto unlock;
+	}
+
+	/* If no side requires MITM protection; auto-accept */
+	if ((!loc_mitm || conn->remote_cap == 0x03) &&
+				(!rem_mitm || conn->io_capability == 0x03)) {
+		BT_DBG("Auto-accept of user confirmation");
+		hci_send_cmd(hdev, HCI_OP_USER_CONFIRM_REPLY,
+						sizeof(ev->bdaddr), &ev->bdaddr);
+		goto unlock;
+	}
+
 	mgmt_user_confirm_request(hdev->id, &ev->bdaddr, ev->passkey);
 
+unlock:
 	hci_dev_unlock(hdev);
 }