Bluetooth: Implement deferred sco socket setup

In order to authenticate and configure an incoming SCO connection, the
BT_DEFER_SETUP option was added. This option is intended to defer reply
to Connect Request on SCO sockets.
When a connection is requested, the listening socket is unblocked but
the effective connection setup happens only on first recv. Any send
between accept and recv fails with -ENOTCONN.

Signed-off-by: Frédéric Dalleau <frederic.dalleau@linux.intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index c6678f2..eea17cd 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -397,6 +397,7 @@
 
 	if (parent) {
 		sk->sk_type = parent->sk_type;
+		bt_sk(sk)->flags = bt_sk(parent)->flags;
 		security_sk_clone(parent, sk);
 	}
 }
@@ -662,6 +663,28 @@
 	return err;
 }
 
+static int sco_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
+			    struct msghdr *msg, size_t len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct sco_pinfo *pi = sco_pi(sk);
+
+	lock_sock(sk);
+
+	if (sk->sk_state == BT_CONNECT2 &&
+	    test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags)) {
+		hci_conn_accept(pi->conn->hcon, 0);
+		sk->sk_state = BT_CONFIG;
+
+		release_sock(sk);
+		return 0;
+	}
+
+	release_sock(sk);
+
+	return bt_sock_recvmsg(iocb, sock, msg, len, flags);
+}
+
 static int sco_sock_setsockopt(struct socket *sock, int level, int optname, char __user *optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
@@ -906,7 +929,10 @@
 		hci_conn_hold(conn->hcon);
 		__sco_chan_add(conn, sk, parent);
 
-		sk->sk_state = BT_CONNECTED;
+		if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags))
+			sk->sk_state = BT_CONNECT2;
+		else
+			sk->sk_state = BT_CONNECTED;
 
 		/* Wake up parent */
 		parent->sk_data_ready(parent, 1);
@@ -919,7 +945,7 @@
 }
 
 /* ----- SCO interface with lower layer (HCI) ----- */
-int sco_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr)
+int sco_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 {
 	struct sock *sk;
 	struct hlist_node *node;
@@ -936,6 +962,9 @@
 		if (!bacmp(&bt_sk(sk)->src, &hdev->bdaddr) ||
 		    !bacmp(&bt_sk(sk)->src, BDADDR_ANY)) {
 			lm |= HCI_LM_ACCEPT;
+
+			if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags))
+				*flags |= HCI_PROTO_DEFER;
 			break;
 		}
 	}
@@ -1024,7 +1053,7 @@
 	.accept		= sco_sock_accept,
 	.getname	= sco_sock_getname,
 	.sendmsg	= sco_sock_sendmsg,
-	.recvmsg	= bt_sock_recvmsg,
+	.recvmsg	= sco_sock_recvmsg,
 	.poll		= bt_sock_poll,
 	.ioctl		= bt_sock_ioctl,
 	.mmap		= sock_no_mmap,