mptcp: Use full MPTCP-level disconnect state machine
RFC 8684 appendix D describes the connection state machine for MPTCP. This patch implements the DATA_FIN / DATA_ACK exchanges and MPTCP-level socket state changes described in that appendix, rather than simply sending DATA_FIN along with TCP FIN when disconnecting subflows. DATA_FIN is now sent and acknowledged before shutting down the subflows. Received DATA_FIN information (if not part of a data packet) is written to the MPTCP socket when the incoming DSS option is parsed by the subflow, and the MPTCP worker is scheduled to process the flag. DATA_FIN received as part of a full DSS mapping will be handled when the mapping is processed. The DATA_FIN is acknowledged by the worker if the reader is caught up. If there is still data to be moved to the MPTCP-level queue, ack_seq will be incremented to account for the DATA_FIN when it reaches the end of the stream and a DATA_ACK will be sent to the peer. Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mat Martineau
David S. Miller
Родитель
16a9a9da17
Коммит
43b54c6ee3
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@ -868,6 +868,17 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
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if (mp_opt.use_ack)
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update_una(msk, &mp_opt);
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/* Zero-length packets, like bare ACKs carrying a DATA_FIN, are
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* dropped by the caller and not propagated to the MPTCP layer.
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* Copy the DATA_FIN information now.
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*/
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if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
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if (mp_opt.data_fin && mp_opt.data_len == 1 &&
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mptcp_update_rcv_data_fin(msk, mp_opt.data_seq) &&
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schedule_work(&msk->work))
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sock_hold(subflow->conn);
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}
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mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
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if (!mpext)
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return;
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@ -381,6 +381,15 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
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*bytes = moved;
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/* If the moves have caught up with the DATA_FIN sequence number
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* it's time to ack the DATA_FIN and change socket state, but
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* this is not a good place to change state. Let the workqueue
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* do it.
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*/
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if (mptcp_pending_data_fin(sk, NULL) &&
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schedule_work(&msk->work))
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sock_hold(sk);
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return done;
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}
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@ -466,7 +475,8 @@ void mptcp_data_acked(struct sock *sk)
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{
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mptcp_reset_timer(sk);
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if (!sk_stream_is_writeable(sk) &&
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if ((!sk_stream_is_writeable(sk) ||
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(inet_sk_state_load(sk) != TCP_ESTABLISHED)) &&
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schedule_work(&mptcp_sk(sk)->work))
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sock_hold(sk);
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}
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@ -1384,6 +1394,7 @@ static void mptcp_worker(struct work_struct *work)
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lock_sock(sk);
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mptcp_clean_una(sk);
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mptcp_check_data_fin_ack(sk);
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__mptcp_flush_join_list(msk);
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__mptcp_move_skbs(msk);
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@ -1393,6 +1404,8 @@ static void mptcp_worker(struct work_struct *work)
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if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
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mptcp_check_for_eof(msk);
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mptcp_check_data_fin(sk);
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if (!test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
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goto unlock;
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@ -1515,7 +1528,7 @@ static void mptcp_cancel_work(struct sock *sk)
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sock_put(sk);
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}
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static void mptcp_subflow_shutdown(struct sock *ssk, int how)
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static void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
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{
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lock_sock(ssk);
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@ -1528,8 +1541,15 @@ static void mptcp_subflow_shutdown(struct sock *ssk, int how)
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tcp_disconnect(ssk, O_NONBLOCK);
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break;
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default:
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if (__mptcp_check_fallback(mptcp_sk(sk))) {
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pr_debug("Fallback");
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ssk->sk_shutdown |= how;
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tcp_shutdown(ssk, how);
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} else {
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pr_debug("Sending DATA_FIN on subflow %p", ssk);
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mptcp_set_timeout(sk, ssk);
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tcp_send_ack(ssk);
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}
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break;
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}
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@ -1570,9 +1590,35 @@ static void mptcp_close(struct sock *sk, long timeout)
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LIST_HEAD(conn_list);
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lock_sock(sk);
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sk->sk_shutdown = SHUTDOWN_MASK;
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if (sk->sk_state == TCP_LISTEN) {
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inet_sk_state_store(sk, TCP_CLOSE);
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goto cleanup;
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} else if (sk->sk_state == TCP_CLOSE) {
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goto cleanup;
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}
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if (__mptcp_check_fallback(msk)) {
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goto update_state;
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} else if (mptcp_close_state(sk)) {
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pr_debug("Sending DATA_FIN sk=%p", sk);
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WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
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WRITE_ONCE(msk->snd_data_fin_enable, 1);
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mptcp_for_each_subflow(msk, subflow) {
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struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
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mptcp_subflow_shutdown(sk, tcp_sk, SHUTDOWN_MASK);
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}
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}
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sk_stream_wait_close(sk, timeout);
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update_state:
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inet_sk_state_store(sk, TCP_CLOSE);
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cleanup:
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/* be sure to always acquire the join list lock, to sync vs
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* mptcp_finish_join().
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*/
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@ -1581,8 +1627,6 @@ static void mptcp_close(struct sock *sk, long timeout)
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spin_unlock_bh(&msk->join_list_lock);
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list_splice_init(&msk->conn_list, &conn_list);
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msk->snd_data_fin_enable = 1;
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__mptcp_clear_xmit(sk);
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release_sock(sk);
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@ -2265,11 +2309,8 @@ static int mptcp_shutdown(struct socket *sock, int how)
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pr_debug("sk=%p, how=%d", msk, how);
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lock_sock(sock->sk);
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if (how == SHUT_WR || how == SHUT_RDWR)
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inet_sk_state_store(sock->sk, TCP_FIN_WAIT1);
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how++;
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if ((how & ~SHUTDOWN_MASK) || !how) {
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ret = -EINVAL;
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goto out_unlock;
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@ -2283,13 +2324,31 @@ static int mptcp_shutdown(struct socket *sock, int how)
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sock->state = SS_CONNECTED;
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}
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__mptcp_flush_join_list(msk);
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msk->snd_data_fin_enable = 1;
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/* If we've already sent a FIN, or it's a closed state, skip this. */
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if (__mptcp_check_fallback(msk)) {
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if (how == SHUT_WR || how == SHUT_RDWR)
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inet_sk_state_store(sock->sk, TCP_FIN_WAIT1);
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mptcp_for_each_subflow(msk, subflow) {
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struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
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mptcp_subflow_shutdown(tcp_sk, how);
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mptcp_subflow_shutdown(sock->sk, tcp_sk, how);
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}
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} else if ((how & SEND_SHUTDOWN) &&
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((1 << sock->sk->sk_state) &
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(TCPF_ESTABLISHED | TCPF_SYN_SENT |
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TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) &&
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mptcp_close_state(sock->sk)) {
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__mptcp_flush_join_list(msk);
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WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
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WRITE_ONCE(msk->snd_data_fin_enable, 1);
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mptcp_for_each_subflow(msk, subflow) {
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struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
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mptcp_subflow_shutdown(sock->sk, tcp_sk, how);
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}
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}
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/* Wake up anyone sleeping in poll. */
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@ -598,7 +598,8 @@ static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
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return true;
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}
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static enum mapping_status get_mapping_status(struct sock *ssk)
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static enum mapping_status get_mapping_status(struct sock *ssk,
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struct mptcp_sock *msk)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
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struct mptcp_ext *mpext;
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@ -648,7 +649,8 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
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if (mpext->data_fin == 1) {
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if (data_len == 1) {
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pr_debug("DATA_FIN with no payload");
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mptcp_update_rcv_data_fin(msk, mpext->data_seq);
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pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
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if (subflow->map_valid) {
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/* A DATA_FIN might arrive in a DSS
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* option before the previous mapping
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@ -660,6 +662,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
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} else {
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return MAPPING_DATA_FIN;
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}
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} else {
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mptcp_update_rcv_data_fin(msk, mpext->data_seq + data_len);
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pr_debug("DATA_FIN with mapping seq=%llu", mpext->data_seq + data_len);
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}
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/* Adjust for DATA_FIN using 1 byte of sequence space */
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@ -748,7 +753,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
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u64 ack_seq;
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u64 old_ack;
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status = get_mapping_status(ssk);
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status = get_mapping_status(ssk, msk);
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pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
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if (status == MAPPING_INVALID) {
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ssk->sk_err = EBADMSG;
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