Bluetooth: Provide msg_name callback for L2CAP connectionless channels

The L2CAP connectionless channels use SOCK_DGRAM and recvmsg() and need
to receive the remote BD_ADDR and PSM information via msg_name from
the recvmsg() system call.

So in case the L2CAP socket is for connectionless channels, provide
a msg_name callback that can update the data. Also store the remote
BD_ADDR and PSM in the skb so it can be extracted later on.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 769c379..f6b5f94 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -6459,6 +6459,10 @@
 	if (chan->imtu < skb->len)
 		goto drop;
 
+	/* Store remote BD_ADDR and PSM for msg_name */
+	bacpy(&bt_cb(skb)->bdaddr, &conn->hcon->dst);
+	bt_cb(skb)->psm = psm;
+
 	if (!chan->ops->recv(chan, skb))
 		return;