rxrpc: Fix missing security check on incoming calls

Fix rxrpc_new_incoming_call() to check that we have a suitable service key
available for the combination of service ID and security class of a new
incoming call - and to reject calls for which we don't.

This causes an assertion like the following to appear:

	rxrpc: Assertion failed - 6(0x6) == 12(0xc) is false
	kernel BUG at net/rxrpc/call_object.c:456!

Where call->state is RXRPC_CALL_SERVER_SECURING (6) rather than
RXRPC_CALL_COMPLETE (12).

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
index 123d6cea..21da48e 100644
--- a/net/rxrpc/conn_service.c
+++ b/net/rxrpc/conn_service.c
@@ -148,6 +148,8 @@ struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxn
  */
 void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
 				   struct rxrpc_connection *conn,
+				   const struct rxrpc_security *sec,
+				   struct key *key,
 				   struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
@@ -160,6 +162,8 @@ void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
 	conn->service_id	= sp->hdr.serviceId;
 	conn->security_ix	= sp->hdr.securityIndex;
 	conn->out_clientflag	= 0;
+	conn->security		= sec;
+	conn->server_key	= key_get(key);
 	if (conn->security_ix)
 		conn->state	= RXRPC_CONN_SERVICE_UNSECURED;
 	else