1 // SPDX-License-Identifier: GPL-2.0
2 /* MPTCP Fast Open Mechanism
3 *
4 * Copyright (c) 2021-2022, Dmytro SHYTYI
5 */
6
7 #include "protocol.h"
8
mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context * subflow,struct request_sock * req)9 void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subflow,
10 struct request_sock *req)
11 {
12 struct sock *sk, *ssk;
13 struct sk_buff *skb;
14 struct tcp_sock *tp;
15 bool has_rxtstamp;
16
17 /* on early fallback the subflow context is deleted by
18 * subflow_syn_recv_sock()
19 */
20 if (!subflow)
21 return;
22
23 ssk = subflow->tcp_sock;
24 sk = subflow->conn;
25 tp = tcp_sk(ssk);
26
27 /* A valid TFO cookie does not guarantee SYN data. */
28 skb = skb_peek(&ssk->sk_receive_queue);
29 if (!skb)
30 return;
31
32 subflow->is_mptfo = 1;
33
34 /* dequeue the skb from sk receive queue */
35 __skb_unlink(skb, &ssk->sk_receive_queue);
36 skb_ext_reset(skb);
37
38 mptcp_subflow_lend_fwdmem(subflow, skb);
39
40 /* We copy the fastopen data, but that don't belong to the mptcp sequence
41 * space, need to offset it in the subflow sequence, see mptcp_subflow_get_map_offset()
42 */
43 tp->copied_seq += skb->len;
44 subflow->ssn_offset += skb->len;
45 has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
46
47 /* Only the sequence delta is relevant */
48 MPTCP_SKB_CB(skb)->map_seq = -skb->len;
49 MPTCP_SKB_CB(skb)->end_seq = 0;
50 MPTCP_SKB_CB(skb)->offset = 0;
51 MPTCP_SKB_CB(skb)->has_rxtstamp = has_rxtstamp;
52 MPTCP_SKB_CB(skb)->cant_coalesce = 1;
53
54 mptcp_data_lock(sk);
55 DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk));
56
57 mptcp_borrow_fwdmem(sk, skb);
58 skb_set_owner_r(skb, sk);
59 __skb_queue_tail(&sk->sk_receive_queue, skb);
60 mptcp_sk(sk)->bytes_received += skb->len;
61
62 sk->sk_data_ready(sk);
63
64 mptcp_data_unlock(sk);
65 }
66