Commit dea2b1ea authored by Paolo Abeni's avatar Paolo Abeni Committed by Jakub Kicinski
Browse files

mptcp: do not reset MP_CAPABLE subflow on mapping errors 

When some mapping related errors occurs we close the main
MPC subflow with a RST. We should instead fallback gracefully
to TCP, and do the reset only for MPJ subflows.

Fixes: d22f4988 ("mptcp: process MP_CAPABLE data option")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/192


Reported-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 06f9a435

net/mptcp/subflow.c

+32 −30
Original line number Diff line number Diff line
@@ -1011,21 +1011,11 @@ static bool subflow_check_data_avail(struct sock *ssk) 


		status = get_mapping_status(ssk, msk);

		trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));

		if (status == MAPPING_INVALID) {

			ssk->sk_err = EBADMSG;

			goto fatal;

		}

		if (status == MAPPING_DUMMY) {

			__mptcp_do_fallback(msk);

			skb = skb_peek(&ssk->sk_receive_queue);

			subflow->map_valid = 1;

			subflow->map_seq = READ_ONCE(msk->ack_seq);

			subflow->map_data_len = skb->len;

			subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq -

						   subflow->ssn_offset;

			subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;

			return true;

		}

		if (unlikely(status == MAPPING_INVALID))

			goto fallback;



		if (unlikely(status == MAPPING_DUMMY))

			goto fallback;



		if (status != MAPPING_OK)

			goto no_data;
@@ -1038,10 +1028,8 @@ static bool subflow_check_data_avail(struct sock *ssk) 
		 * MP_CAPABLE-based mapping

		 */

		if (unlikely(!READ_ONCE(msk->can_ack))) {

			if (!subflow->mpc_map) {

				ssk->sk_err = EBADMSG;

				goto fatal;

			}

			if (!subflow->mpc_map)

				goto fallback;

			WRITE_ONCE(msk->remote_key, subflow->remote_key);

			WRITE_ONCE(msk->ack_seq, subflow->map_seq);

			WRITE_ONCE(msk->can_ack, true);
@@ -1069,10 +1057,14 @@ static bool subflow_check_data_avail(struct sock *ssk) 
no_data:

	subflow_sched_work_if_closed(msk, ssk);

	return false;

fatal:

	/* fatal protocol error, close the socket */

	/* This barrier is coupled with smp_rmb() in tcp_poll() */

	smp_wmb();



fallback:

	/* RFC 8684 section 3.7. */

	if (subflow->mp_join || subflow->fully_established) {

		/* fatal protocol error, close the socket.

		 * subflow_error_report() will introduce the appropriate barriers

		 */

		ssk->sk_err = EBADMSG;

		ssk->sk_error_report(ssk);

		tcp_set_state(ssk, TCP_CLOSE);

		subflow->reset_transient = 0;
@@ -1082,6 +1074,16 @@ static bool subflow_check_data_avail(struct sock *ssk) 
		return false;

	}



	__mptcp_do_fallback(msk);

	skb = skb_peek(&ssk->sk_receive_queue);

	subflow->map_valid = 1;

	subflow->map_seq = READ_ONCE(msk->ack_seq);

	subflow->map_data_len = skb->len;

	subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;

	subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;

	return true;

}



bool mptcp_subflow_data_available(struct sock *sk)

{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);