1 files changed, 81 insertions, 0 deletions
diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c
new file mode 100644
index 0000000000..74698582a2
--- /dev/null
+++ b/net/mptcp/fastopen.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/* MPTCP Fast Open Mechanism
+ *
+ * Copyright (c) 2021-2022, Dmytro SHYTYI
+ */
+
+#include "protocol.h"
+
+void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subflow,
+					      struct request_sock *req)
+{
+	struct sock *sk, *ssk;
+	struct sk_buff *skb;
+	struct tcp_sock *tp;
+
+	/* on early fallback the subflow context is deleted by
+	 * subflow_syn_recv_sock()
+	 */
+	if (!subflow)
+		return;
+
+	ssk = subflow->tcp_sock;
+	sk = subflow->conn;
+	tp = tcp_sk(ssk);
+
+	subflow->is_mptfo = 1;
+
+	skb = skb_peek(&ssk->sk_receive_queue);
+	if (WARN_ON_ONCE(!skb))
+		return;
+
+	/* dequeue the skb from sk receive queue */
+	__skb_unlink(skb, &ssk->sk_receive_queue);
+	skb_ext_reset(skb);
+	skb_orphan(skb);
+
+	/* We copy the fastopen data, but that don't belong to the mptcp sequence
+	 * space, need to offset it in the subflow sequence, see mptcp_subflow_get_map_offset()
+	 */
+	tp->copied_seq += skb->len;
+	subflow->ssn_offset += skb->len;
+
+	/* initialize a dummy sequence number, we will update it at MPC
+	 * completion, if needed
+	 */
+	MPTCP_SKB_CB(skb)->map_seq = -skb->len;
+	MPTCP_SKB_CB(skb)->end_seq = 0;
+	MPTCP_SKB_CB(skb)->offset = 0;
+	MPTCP_SKB_CB(skb)->has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
+
+	mptcp_data_lock(sk);
+
+	mptcp_set_owner_r(skb, sk);
+	__skb_queue_tail(&sk->sk_receive_queue, skb);
+	mptcp_sk(sk)->bytes_received += skb->len;
+
+	sk->sk_data_ready(sk);
+
+	mptcp_data_unlock(sk);
+}
+
+void mptcp_fastopen_gen_msk_ackseq(struct mptcp_sock *msk, struct mptcp_subflow_context *subflow,
+				   const struct mptcp_options_received *mp_opt)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct sk_buff *skb;
+
+	mptcp_data_lock(sk);
+	skb = skb_peek_tail(&sk->sk_receive_queue);
+	if (skb) {
+		WARN_ON_ONCE(MPTCP_SKB_CB(skb)->end_seq);
+		pr_debug("msk %p moving seq %llx -> %llx end_seq %llx -> %llx", sk,
+			 MPTCP_SKB_CB(skb)->map_seq, MPTCP_SKB_CB(skb)->map_seq + msk->ack_seq,
+			 MPTCP_SKB_CB(skb)->end_seq, MPTCP_SKB_CB(skb)->end_seq + msk->ack_seq);
+		MPTCP_SKB_CB(skb)->map_seq += msk->ack_seq;
+		MPTCP_SKB_CB(skb)->end_seq += msk->ack_seq;
+	}
+
+	pr_debug("msk=%p ack_seq=%llx", msk, msk->ack_seq);
+	mptcp_data_unlock(sk);
+}