// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP
*
* Copyright (c) 2017 - 2019, Intel Corporation.
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/sched/signal.h>
#include <linux/atomic.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/protocol.h>
#include <net/tcp.h>
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
#include <net/transp_v6.h>
#endif
#include <net/mptcp.h>
#include "protocol.h"
#define MPTCP_SAME_STATE TCP_MAX_STATES
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
struct mptcp6_sock {
struct mptcp_sock msk;
struct ipv6_pinfo np;
};
#endif
struct mptcp_skb_cb {
u32 offset;
};
#define MPTCP_SKB_CB(__skb) ((struct mptcp_skb_cb *)&((__skb)->cb[0]))
/* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not
* completed yet or has failed, return the subflow socket.
* Otherwise return NULL.
*/
static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
{
if (!msk->subflow || READ_ONCE(msk->can_ack))
return NULL;
return msk->subflow;
}
static bool __mptcp_needs_tcp_fallback(const struct mptcp_sock *msk)
{
return msk->first && !sk_is_mptcp(msk->first);
}
static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk)
{
sock_owned_by_me((const struct sock *)msk);
if (likely(!__mptcp_needs_tcp_fallback(msk