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
9void 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
16	/* on early fallback the subflow context is deleted by
17	 * subflow_syn_recv_sock()
18	 */
19	if (!subflow)
20		return;
21
22	ssk = subflow->tcp_sock;
23	sk = subflow->conn;
24	tp = tcp_sk(ssk);
25
26	subflow->is_mptfo = 1;
27
28	skb = skb_peek(&ssk->sk_receive_queue);
29	if (WARN_ON_ONCE(!skb))
30		return;
31
32	/* dequeue the skb from sk receive queue */
33	__skb_unlink(skb, &ssk->sk_receive_queue);
34	skb_ext_reset(skb);
35	skb_orphan(skb);
36
37	/* We copy the fastopen data, but that don't belong to the mptcp sequence
38	 * space, need to offset it in the subflow sequence, see mptcp_subflow_get_map_offset()
39	 */
40	tp->copied_seq += skb->len;
41	subflow->ssn_offset += skb->len;
42
43	/* initialize a dummy sequence number, we will update it at MPC
44	 * completion, if needed
45	 */
46	MPTCP_SKB_CB(skb)->map_seq = -skb->len;
47	MPTCP_SKB_CB(skb)->end_seq = 0;
48	MPTCP_SKB_CB(skb)->offset = 0;
49	MPTCP_SKB_CB(skb)->has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
50
51	mptcp_data_lock(sk);
52
53	mptcp_set_owner_r(skb, sk);
54	__skb_queue_tail(&sk->sk_receive_queue, skb);
55	mptcp_sk(sk)->bytes_received += skb->len;
56
57	sk->sk_data_ready(sk);
58
59	mptcp_data_unlock(sk);
60}
61
62void __mptcp_fastopen_gen_msk_ackseq(struct mptcp_sock *msk, struct mptcp_subflow_context *subflow,
63				     const struct mptcp_options_received *mp_opt)
64{
65	struct sock *sk = (struct sock *)msk;
66	struct sk_buff *skb;
67
68	skb = skb_peek_tail(&sk->sk_receive_queue);
69	if (skb) {
70		WARN_ON_ONCE(MPTCP_SKB_CB(skb)->end_seq);
71		pr_debug("msk %p moving seq %llx -> %llx end_seq %llx -> %llx", sk,
72			 MPTCP_SKB_CB(skb)->map_seq, MPTCP_SKB_CB(skb)->map_seq + msk->ack_seq,
73			 MPTCP_SKB_CB(skb)->end_seq, MPTCP_SKB_CB(skb)->end_seq + msk->ack_seq);
74		MPTCP_SKB_CB(skb)->map_seq += msk->ack_seq;
75		MPTCP_SKB_CB(skb)->end_seq += msk->ack_seq;
76	}
77
78	pr_debug("msk=%p ack_seq=%llx", msk, msk->ack_seq);
79}
80