rxrpc: Fix accept on a connection that need securing

When a new incoming call arrives at an userspace rxrpc socket on a new
connection that has a security class set, the code currently pushes it onto
the accept queue to hold a ref on it for the socket.  This doesn't work,
however, as recvmsg() pops it off, notices that it's in the SERVER_SECURING
state and discards the ref.  This means that the call runs out of refs too
early and the kernel oopses.

By contrast, a kernel rxrpc socket manually pre-charges the incoming call
pool with calls that already have user call IDs assigned, so they are ref'd
by the call tree on the socket.

Change the mode of operation for userspace rxrpc server sockets to work
like this too.  Although this is a UAPI change, server sockets aren't
currently functional.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 1 insertions, 35 deletions

diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index c4684dde1f16..2c842851d72e 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -179,37 +179,6 @@ static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
 }
 
 /*
- * Pass back notification of a new call.  The call is added to the
- * to-be-accepted list.  This means that the next call to be accepted might not
- * be the last call seen awaiting acceptance, but unless we leave this on the
- * front of the queue and block all other messages until someone gives us a
- * user_ID for it, there's not a lot we can do.
- */
-static int rxrpc_recvmsg_new_call(struct rxrpc_sock *rx,
-				  struct rxrpc_call *call,
-				  struct msghdr *msg, int flags)
-{
-	int tmp = 0, ret;
-
-	ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &tmp);
-
-	if (ret == 0 && !(flags & MSG_PEEK)) {
-		_debug("to be accepted");
-		write_lock_bh(&rx->recvmsg_lock);
-		list_del_init(&call->recvmsg_link);
-		write_unlock_bh(&rx->recvmsg_lock);
-
-		rxrpc_get_call(call, rxrpc_call_got);
-		write_lock(&rx->call_lock);
-		list_add_tail(&call->accept_link, &rx->to_be_accepted);
-		write_unlock(&rx->call_lock);
-	}
-
-	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_to_be_accepted, 1, 0, 0, ret);
-	return ret;
-}
-
-/*
  * End the packet reception phase.
  */
 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
@@ -630,9 +599,6 @@ try_again:
 	}
 
 	switch (READ_ONCE(call->state)) {
-	case RXRPC_CALL_SERVER_ACCEPTING:
-		ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
-		break;
 	case RXRPC_CALL_CLIENT_RECV_REPLY:
 	case RXRPC_CALL_SERVER_RECV_REQUEST:
 	case RXRPC_CALL_SERVER_ACK_REQUEST:
@@ -728,7 +694,7 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 	       call->debug_id, rxrpc_call_states[call->state],
 	       iov_iter_count(iter), want_more);
 
-	ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
+	ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);
 
 	mutex_lock(&call->user_mutex);