rxrpc: Trace protocol errors in received packets

Add a tracepoint (rxrpc_rx_proto) to record protocol errors in received
packets.  The following changes are made:

 (1) Add a function, __rxrpc_abort_eproto(), to note a protocol error on a
     call and mark the call aborted.  This is wrapped by
     rxrpc_abort_eproto() that makes the why string usable in trace.

 (2) Add trace_rxrpc_rx_proto() or rxrpc_abort_eproto() to protocol error
     generation points, replacing rxrpc_abort_call() with the latter.

 (3) Only send an abort packet in rxkad_verify_packet*() if we actually
     managed to abort the call.

Note that a trace event is also emitted if a kernel user (e.g. afs) tries
to send data through a call when it's not in the transmission phase, though
it's not technically a receive event.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index f9d1d9cc86d8..46babcf82ce8 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -281,8 +281,11 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 
 	case RXRPC_PACKET_TYPE_ABORT:
 		if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
-				  &wtmp, sizeof(wtmp)) < 0)
+				  &wtmp, sizeof(wtmp)) < 0) {
+			trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
+					      tracepoint_string("bad_abort"));
 			return -EPROTO;
+		}
 		abort_code = ntohl(wtmp);
 		_proto("Rx ABORT %%%u { ac=%d }", sp->hdr.serial, abort_code);
 
@@ -327,7 +330,8 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 		return 0;
 
 	default:
-		_leave(" = -EPROTO [%u]", sp->hdr.type);
+		trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
+				      tracepoint_string("bad_conn_pkt"));
 		return -EPROTO;
 	}
 }
@@ -422,6 +426,5 @@ protocol_error:
 	if (rxrpc_abort_connection(conn, ret, abort_code) < 0)
 		goto requeue_and_leave;
 	rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
-	_leave(" [EPROTO]");
 	goto out;
 }