rxrpc: Be more selective about the types of received packets we accept

Currently, received RxRPC packets outside the range 1-13 are rejected.
There are, however, holes in the range that should also be rejected - plus
at least one type we don't yet support - so reject these also.
Signed-off-by: David Howells <dhowells@redhat.com>

include/rxrpc/packet.h

@@ -70,6 +70,17 @@ struct rxrpc_wire_header {
 
 extern const char *rxrpc_pkts[];
 
+#define RXRPC_SUPPORTED_PACKET_TYPES (			\
+		(1 << RXRPC_PACKET_TYPE_DATA) |		\
+		(1 << RXRPC_PACKET_TYPE_ACK) |		\
+		(1 << RXRPC_PACKET_TYPE_BUSY) |		\
+		(1 << RXRPC_PACKET_TYPE_ABORT) |	\
+		(1 << RXRPC_PACKET_TYPE_ACKALL) |	\
+		(1 << RXRPC_PACKET_TYPE_CHALLENGE) |	\
+		(1 << RXRPC_PACKET_TYPE_RESPONSE) |	\
+		/*(1 << RXRPC_PACKET_TYPE_DEBUG) | */	\
+		(1 << RXRPC_PACKET_TYPE_VERSION))
+
 /*****************************************************************************/
 /*
  * jumbo packet secondary header

net/rxrpc/ar-input.c

@@ -728,7 +728,8 @@ void rxrpc_data_ready(struct sock *sk)
 	     sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
 	     sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
 
-	if (sp->hdr.type == 0 || sp->hdr.type >= RXRPC_N_PACKET_TYPES) {
+	if (sp->hdr.type >= RXRPC_N_PACKET_TYPES ||
+	    !((RXRPC_SUPPORTED_PACKET_TYPES >> sp->hdr.type) & 1)) {
 		_proto("Rx Bad Packet Type %u", sp->hdr.type);
 		goto bad_message;
 	}