net/mptcp/protocol.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /* Multipath TCP
  *
  * Copyright (c) 2017 - 2019, Intel Corporation.
  */

 #ifndef __MPTCP_PROTOCOL_H
 #define __MPTCP_PROTOCOL_H

 #include <linux/random.h>
 #include <net/tcp.h>
 #include <net/inet_connection_sock.h>

 #define MPTCP_SUPPORTED_VERSION	1

 /* MPTCP option bits */
 #define OPTION_MPTCP_MPC_SYN	BIT(0)
 #define OPTION_MPTCP_MPC_SYNACK	BIT(1)
 #define OPTION_MPTCP_MPC_ACK	BIT(2)
 #define OPTION_MPTCP_MPJ_SYN	BIT(3)
 #define OPTION_MPTCP_MPJ_SYNACK	BIT(4)
 #define OPTION_MPTCP_MPJ_ACK	BIT(5)
 #define OPTION_MPTCP_ADD_ADDR	BIT(6)
 #define OPTION_MPTCP_ADD_ADDR6	BIT(7)
 #define OPTION_MPTCP_RM_ADDR	BIT(8)

 /* MPTCP option subtypes */
 #define MPTCPOPT_MP_CAPABLE	0
 #define MPTCPOPT_MP_JOIN	1
 #define MPTCPOPT_DSS		2
 #define MPTCPOPT_ADD_ADDR	3
 #define MPTCPOPT_RM_ADDR	4
 #define MPTCPOPT_MP_PRIO	5
 #define MPTCPOPT_MP_FAIL	6
 #define MPTCPOPT_MP_FASTCLOSE	7

 /* MPTCP suboption lengths */
 #define TCPOLEN_MPTCP_MPC_SYN		4
 #define TCPOLEN_MPTCP_MPC_SYNACK	12
 #define TCPOLEN_MPTCP_MPC_ACK		20
 #define TCPOLEN_MPTCP_MPC_ACK_DATA	22
 #define TCPOLEN_MPTCP_MPJ_SYN		12
 #define TCPOLEN_MPTCP_MPJ_SYNACK	16
 #define TCPOLEN_MPTCP_MPJ_ACK		24
 #define TCPOLEN_MPTCP_DSS_BASE		4
 #define TCPOLEN_MPTCP_DSS_ACK32		4
 #define TCPOLEN_MPTCP_DSS_ACK64		8
 #define TCPOLEN_MPTCP_DSS_MAP32		10
 #define TCPOLEN_MPTCP_DSS_MAP64		14
 #define TCPOLEN_MPTCP_DSS_CHECKSUM	2
 #define TCPOLEN_MPTCP_ADD_ADDR		16
 #define TCPOLEN_MPTCP_ADD_ADDR_PORT	18
 #define TCPOLEN_MPTCP_ADD_ADDR_BASE	8
 #define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT	10
 #define TCPOLEN_MPTCP_ADD_ADDR6		28
 #define TCPOLEN_MPTCP_ADD_ADDR6_PORT	30
 #define TCPOLEN_MPTCP_ADD_ADDR6_BASE	20
 #define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT	22
 #define TCPOLEN_MPTCP_PORT_LEN		2
 #define TCPOLEN_MPTCP_RM_ADDR_BASE	4

 /* MPTCP MP_JOIN flags */
 #define MPTCPOPT_BACKUP		BIT(0)
 #define MPTCPOPT_HMAC_LEN	20
 #define MPTCPOPT_THMAC_LEN	8

 /* MPTCP MP_CAPABLE flags */
 #define MPTCP_VERSION_MASK	(0x0F)
 #define MPTCP_CAP_CHECKSUM_REQD	BIT(7)
 #define MPTCP_CAP_EXTENSIBILITY	BIT(6)
 #define MPTCP_CAP_HMAC_SHA256	BIT(0)
 #define MPTCP_CAP_FLAG_MASK	(0x3F)

 /* MPTCP DSS flags */
 #define MPTCP_DSS_DATA_FIN	BIT(4)
 #define MPTCP_DSS_DSN64		BIT(3)
 #define MPTCP_DSS_HAS_MAP	BIT(2)
 #define MPTCP_DSS_ACK64		BIT(1)
 #define MPTCP_DSS_HAS_ACK	BIT(0)
 #define MPTCP_DSS_FLAG_MASK	(0x1F)

 /* MPTCP ADD_ADDR flags */
 #define MPTCP_ADDR_ECHO		BIT(0)
 #define MPTCP_ADDR_IPVERSION_4	4
 #define MPTCP_ADDR_IPVERSION_6	6

 /* MPTCP socket flags */
 #define MPTCP_DATA_READY	0
 #define MPTCP_SEND_SPACE	1
 #define MPTCP_WORK_RTX		2
 #define MPTCP_WORK_EOF		3

 struct mptcp_options_received {
 	u64	sndr_key;
 	u64	rcvr_key;
 	u64	data_ack;
 	u64	data_seq;
 	u32	subflow_seq;
 	u16	data_len;
 	u16	mp_capable : 1,
 		mp_join : 1,
 		dss : 1,
 		add_addr : 1,
 		rm_addr : 1,
 		family : 4,
 		echo : 1,
 		backup : 1;
 	u32	token;
 	u32	nonce;
 	u64	thmac;
 	u8	hmac[20];
 	u8	join_id;
 	u8	use_map:1,
 		dsn64:1,
 		data_fin:1,
 		use_ack:1,
 		ack64:1,
 		mpc_map:1,
 		__unused:2;
 	u8	addr_id;
 	u8	rm_id;
 	union {
 		struct in_addr	addr;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 		struct in6_addr	addr6;
 #endif
 	};
 	u64	ahmac;
 	u16	port;
 };

 static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
 {
 	return htonl((TCPOPT_MPTCP << 24) | (len << 16) | (subopt << 12) |
 		     ((nib & 0xF) << 8) | field);
 }

 struct mptcp_addr_info {
 	sa_family_t		family;
 	__be16			port;
 	u8			id;
 	union {
 		struct in_addr addr;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 		struct in6_addr addr6;
 #endif
 	};
 };

 enum mptcp_pm_status {
 	MPTCP_PM_ADD_ADDR_RECEIVED,
 	MPTCP_PM_ESTABLISHED,
 	MPTCP_PM_SUBFLOW_ESTABLISHED,
 };

 struct mptcp_pm_data {
 	struct mptcp_addr_info local;
 	struct mptcp_addr_info remote;

 	spinlock_t	lock;		/*protects the whole PM data */

 	bool		addr_signal;
 	bool		server_side;
 	bool		work_pending;
 	bool		accept_addr;
 	bool		accept_subflow;
 	u8		add_addr_signaled;
 	u8		add_addr_accepted;
 	u8		local_addr_used;
 	u8		subflows;
 	u8		add_addr_signal_max;
 	u8		add_addr_accept_max;
 	u8		local_addr_max;
 	u8		subflows_max;
 	u8		status;

 	struct		work_struct work;
 };

 struct mptcp_data_frag {
 	struct list_head list;
 	u64 data_seq;
 	int data_len;
 	int offset;
 	int overhead;
 	struct page *page;
 };

 /* MPTCP connection sock */
 struct mptcp_sock {
 	/* inet_connection_sock must be the first member */
 	struct inet_connection_sock sk;
 	u64		local_key;
 	u64		remote_key;
 	u64		write_seq;
 	u64		ack_seq;
 	atomic64_t	snd_una;
 	unsigned long	timer_ival;
 	u32		token;
 	unsigned long	flags;
 	bool		can_ack;
 	spinlock_t	join_list_lock;
 	struct work_struct work;
 	struct list_head conn_list;
 	struct list_head rtx_queue;
 	struct list_head join_list;
 	struct skb_ext	*cached_ext;	/* for the next sendmsg */
 	struct socket	*subflow; /* outgoing connect/listener/!mp_capable */
 	struct sock	*first;
 	struct mptcp_pm_data	pm;
 };

 #define mptcp_for_each_subflow(__msk, __subflow)			\
 	list_for_each_entry(__subflow, &((__msk)->conn_list), node)

 static inline struct mptcp_sock *mptcp_sk(const struct sock *sk)
 {
 	return (struct mptcp_sock *)sk;
 }

 static inline struct mptcp_data_frag *mptcp_rtx_tail(const struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);

 	if (list_empty(&msk->rtx_queue))
 		return NULL;

 	return list_last_entry(&msk->rtx_queue, struct mptcp_data_frag, list);
 }

 static inline struct mptcp_data_frag *mptcp_rtx_head(const struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);

 	return list_first_entry_or_null(&msk->rtx_queue, struct mptcp_data_frag, list);
 }

 struct mptcp_subflow_request_sock {
 	struct	tcp_request_sock sk;
 	u16	mp_capable : 1,
 		mp_join : 1,
 		backup : 1;
 	u8	local_id;
 	u8	remote_id;
 	u64	local_key;
 	u64	idsn;
 	u32	token;
 	u32	ssn_offset;
 	u64	thmac;
 	u32	local_nonce;
 	u32	remote_nonce;
 	struct mptcp_sock	*msk;
 };

 static inline struct mptcp_subflow_request_sock *
 mptcp_subflow_rsk(const struct request_sock *rsk)
 {
 	return (struct mptcp_subflow_request_sock *)rsk;
 }

 /* MPTCP subflow context */
 struct mptcp_subflow_context {
 	struct	list_head node;/* conn_list of subflows */
 	u64	local_key;
 	u64	remote_key;
 	u64	idsn;
 	u64	map_seq;
 	u32	snd_isn;
 	u32	token;
 	u32	rel_write_seq;
 	u32	map_subflow_seq;
 	u32	ssn_offset;
 	u32	map_data_len;
 	u32	request_mptcp : 1,  /* send MP_CAPABLE */
 		request_join : 1,   /* send MP_JOIN */
 		request_bkup : 1,
 		mp_capable : 1,	    /* remote is MPTCP capable */
 		mp_join : 1,	    /* remote is JOINing */
 		fully_established : 1,	    /* path validated */
 		pm_notified : 1,    /* PM hook called for established status */
 		conn_finished : 1,
 		map_valid : 1,
 		mpc_map : 1,
 		backup : 1,
 		data_avail : 1,
 		rx_eof : 1,
 		data_fin_tx_enable : 1,
 		use_64bit_ack : 1, /* Set when we received a 64-bit DSN */
 		can_ack : 1;	    /* only after processing the remote a key */
 	u64	data_fin_tx_seq;
 	u32	remote_nonce;
 	u64	thmac;
 	u32	local_nonce;
 	u32	remote_token;
 	u8	hmac[MPTCPOPT_HMAC_LEN];
 	u8	local_id;
 	u8	remote_id;

 	struct	sock *tcp_sock;	    /* tcp sk backpointer */
 	struct	sock *conn;	    /* parent mptcp_sock */
 	const	struct inet_connection_sock_af_ops *icsk_af_ops;
 	void	(*tcp_data_ready)(struct sock *sk);
 	void	(*tcp_state_change)(struct sock *sk);
 	void	(*tcp_write_space)(struct sock *sk);

 	struct	rcu_head rcu;
 };

 static inline struct mptcp_subflow_context *
 mptcp_subflow_ctx(const struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);

 	/* Use RCU on icsk_ulp_data only for sock diag code */
 	return (__force struct mptcp_subflow_context *)icsk->icsk_ulp_data;
 }

 static inline struct sock *
 mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
 {
 	return subflow->tcp_sock;
 }

 static inline u64
 mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
 {
 	return tcp_sk(mptcp_subflow_tcp_sock(subflow))->copied_seq -
 		      subflow->ssn_offset -
 		      subflow->map_subflow_seq;
 }

 static inline u64
 mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
 {
 	return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
 }

 int mptcp_is_enabled(struct net *net);
 bool mptcp_subflow_data_available(struct sock *sk);
 void mptcp_subflow_init(void);

 /* called with sk socket lock held */
 int __mptcp_subflow_connect(struct sock *sk, int ifindex,
 			    const struct mptcp_addr_info *loc,
 			    const struct mptcp_addr_info *remote);
 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock);

 static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
 					      struct mptcp_subflow_context *ctx)
 {
 	sk->sk_data_ready = ctx->tcp_data_ready;
 	sk->sk_state_change = ctx->tcp_state_change;
 	sk->sk_write_space = ctx->tcp_write_space;

 	inet_csk(sk)->icsk_af_ops = ctx->icsk_af_ops;
 }

 extern const struct inet_connection_sock_af_ops ipv4_specific;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 extern const struct inet_connection_sock_af_ops ipv6_specific;
 #endif

 void mptcp_proto_init(void);
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 int mptcp_proto_v6_init(void);
 #endif

 struct sock *mptcp_sk_clone(const struct sock *sk,
 			    const struct mptcp_options_received *mp_opt,
 			    struct request_sock *req);
 void mptcp_get_options(const struct sk_buff *skb,
 		       struct mptcp_options_received *mp_opt);

 void mptcp_finish_connect(struct sock *sk);
 void mptcp_data_ready(struct sock *sk, struct sock *ssk);
 bool mptcp_finish_join(struct sock *sk);
 void mptcp_data_acked(struct sock *sk);
 void mptcp_subflow_eof(struct sock *sk);

 int mptcp_token_new_request(struct request_sock *req);
 void mptcp_token_destroy_request(u32 token);
 int mptcp_token_new_connect(struct sock *sk);
 int mptcp_token_new_accept(u32 token, struct sock *conn);
 struct mptcp_sock *mptcp_token_get_sock(u32 token);
 void mptcp_token_destroy(u32 token);

 void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn);
 static inline void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
 {
 	/* we might consider a faster version that computes the key as a
 	 * hash of some information available in the MPTCP socket. Use
 	 * random data at the moment, as it's probably the safest option
 	 * in case multiple sockets are opened in different namespaces at
 	 * the same time.
 	 */
 	get_random_bytes(key, sizeof(u64));
 	mptcp_crypto_key_sha(*key, token, idsn);
 }

 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);

 void mptcp_pm_init(void);
 void mptcp_pm_data_init(struct mptcp_sock *msk);
 void mptcp_pm_close(struct mptcp_sock *msk);
 void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side);
 void mptcp_pm_fully_established(struct mptcp_sock *msk);
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
 void mptcp_pm_connection_closed(struct mptcp_sock *msk);
 void mptcp_pm_subflow_established(struct mptcp_sock *msk,
 				  struct mptcp_subflow_context *subflow);
 void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id);
 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 				const struct mptcp_addr_info *addr);

 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   const struct mptcp_addr_info *addr);
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id);
 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id);

 static inline bool mptcp_pm_should_signal(struct mptcp_sock *msk)
 {
 	return READ_ONCE(msk->pm.addr_signal);
 }

 static inline unsigned int mptcp_add_addr_len(int family)
 {
 	if (family == AF_INET)
 		return TCPOLEN_MPTCP_ADD_ADDR;
 	return TCPOLEN_MPTCP_ADD_ADDR6;
 }

 bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 			  struct mptcp_addr_info *saddr);
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);

 void mptcp_pm_nl_init(void);
 void mptcp_pm_nl_data_init(struct mptcp_sock *msk);
 void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
 void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
 void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk);
 int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);

 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
 {
 	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);
 }

 static inline bool before64(__u64 seq1, __u64 seq2)
 {
 	return (__s64)(seq1 - seq2) < 0;
 }

 #define after64(seq2, seq1)	before64(seq1, seq2)

 void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops);

 #endif /* __MPTCP_PROTOCOL_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/* Multipath TCP
	*
	* Copyright (c) 2017 - 2019, Intel Corporation.
	*/

	#ifndef __MPTCP_PROTOCOL_H
	#define __MPTCP_PROTOCOL_H

	#include <linux/random.h>
	#include <net/tcp.h>
	#include <net/inet_connection_sock.h>

	#define MPTCP_SUPPORTED_VERSION 1

	/* MPTCP option bits */
	#define OPTION_MPTCP_MPC_SYN BIT(0)
	#define OPTION_MPTCP_MPC_SYNACK BIT(1)
	#define OPTION_MPTCP_MPC_ACK BIT(2)
	#define OPTION_MPTCP_MPJ_SYN BIT(3)
	#define OPTION_MPTCP_MPJ_SYNACK BIT(4)
	#define OPTION_MPTCP_MPJ_ACK BIT(5)
	#define OPTION_MPTCP_ADD_ADDR BIT(6)
	#define OPTION_MPTCP_ADD_ADDR6 BIT(7)
	#define OPTION_MPTCP_RM_ADDR BIT(8)

	/* MPTCP option subtypes */
	#define MPTCPOPT_MP_CAPABLE 0
	#define MPTCPOPT_MP_JOIN 1
	#define MPTCPOPT_DSS 2
	#define MPTCPOPT_ADD_ADDR 3
	#define MPTCPOPT_RM_ADDR 4
	#define MPTCPOPT_MP_PRIO 5
	#define MPTCPOPT_MP_FAIL 6
	#define MPTCPOPT_MP_FASTCLOSE 7

	/* MPTCP suboption lengths */
	#define TCPOLEN_MPTCP_MPC_SYN 4
	#define TCPOLEN_MPTCP_MPC_SYNACK 12
	#define TCPOLEN_MPTCP_MPC_ACK 20
	#define TCPOLEN_MPTCP_MPC_ACK_DATA 22
	#define TCPOLEN_MPTCP_MPJ_SYN 12
	#define TCPOLEN_MPTCP_MPJ_SYNACK 16
	#define TCPOLEN_MPTCP_MPJ_ACK 24
	#define TCPOLEN_MPTCP_DSS_BASE 4
	#define TCPOLEN_MPTCP_DSS_ACK32 4
	#define TCPOLEN_MPTCP_DSS_ACK64 8
	#define TCPOLEN_MPTCP_DSS_MAP32 10
	#define TCPOLEN_MPTCP_DSS_MAP64 14
	#define TCPOLEN_MPTCP_DSS_CHECKSUM 2
	#define TCPOLEN_MPTCP_ADD_ADDR 16
	#define TCPOLEN_MPTCP_ADD_ADDR_PORT 18
	#define TCPOLEN_MPTCP_ADD_ADDR_BASE 8
	#define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT 10
	#define TCPOLEN_MPTCP_ADD_ADDR6 28
	#define TCPOLEN_MPTCP_ADD_ADDR6_PORT 30
	#define TCPOLEN_MPTCP_ADD_ADDR6_BASE 20
	#define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT 22
	#define TCPOLEN_MPTCP_PORT_LEN 2
	#define TCPOLEN_MPTCP_RM_ADDR_BASE 4

	/* MPTCP MP_JOIN flags */
	#define MPTCPOPT_BACKUP BIT(0)
	#define MPTCPOPT_HMAC_LEN 20
	#define MPTCPOPT_THMAC_LEN 8

	/* MPTCP MP_CAPABLE flags */
	#define MPTCP_VERSION_MASK (0x0F)
	#define MPTCP_CAP_CHECKSUM_REQD BIT(7)
	#define MPTCP_CAP_EXTENSIBILITY BIT(6)
	#define MPTCP_CAP_HMAC_SHA256 BIT(0)
	#define MPTCP_CAP_FLAG_MASK (0x3F)

	/* MPTCP DSS flags */
	#define MPTCP_DSS_DATA_FIN BIT(4)
	#define MPTCP_DSS_DSN64 BIT(3)
	#define MPTCP_DSS_HAS_MAP BIT(2)
	#define MPTCP_DSS_ACK64 BIT(1)
	#define MPTCP_DSS_HAS_ACK BIT(0)
	#define MPTCP_DSS_FLAG_MASK (0x1F)

	/* MPTCP ADD_ADDR flags */
	#define MPTCP_ADDR_ECHO BIT(0)
	#define MPTCP_ADDR_IPVERSION_4 4
	#define MPTCP_ADDR_IPVERSION_6 6

	/* MPTCP socket flags */
	#define MPTCP_DATA_READY 0
	#define MPTCP_SEND_SPACE 1
	#define MPTCP_WORK_RTX 2
	#define MPTCP_WORK_EOF 3

	struct mptcp_options_received {
	u64 sndr_key;
	u64 rcvr_key;
	u64 data_ack;
	u64 data_seq;
	u32 subflow_seq;
	u16 data_len;
	u16 mp_capable : 1,
	mp_join : 1,
	dss : 1,
	add_addr : 1,
	rm_addr : 1,
	family : 4,
	echo : 1,
	backup : 1;
	u32 token;
	u32 nonce;
	u64 thmac;
	u8 hmac[20];
	u8 join_id;
	u8 use_map:1,
	dsn64:1,
	data_fin:1,
	use_ack:1,
	ack64:1,
	mpc_map:1,
	__unused:2;
	u8 addr_id;
	u8 rm_id;
	union {
	struct in_addr addr;
	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
	struct in6_addr addr6;
	#endif
	};
	u64 ahmac;
	u16 port;
	};

	static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
	{
	return htonl((TCPOPT_MPTCP << 24) \| (len << 16) \| (subopt << 12) \|
	((nib & 0xF) << 8) \| field);
	}

	struct mptcp_addr_info {
	sa_family_t family;
	__be16 port;
	u8 id;
	union {
	struct in_addr addr;
	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
	struct in6_addr addr6;
	#endif
	};
	};

	enum mptcp_pm_status {
	MPTCP_PM_ADD_ADDR_RECEIVED,
	MPTCP_PM_ESTABLISHED,
	MPTCP_PM_SUBFLOW_ESTABLISHED,
	};

	struct mptcp_pm_data {
	struct mptcp_addr_info local;
	struct mptcp_addr_info remote;

	spinlock_t lock; /protects the whole PM data /

	bool addr_signal;
	bool server_side;
	bool work_pending;
	bool accept_addr;
	bool accept_subflow;
	u8 add_addr_signaled;
	u8 add_addr_accepted;
	u8 local_addr_used;
	u8 subflows;
	u8 add_addr_signal_max;
	u8 add_addr_accept_max;
	u8 local_addr_max;
	u8 subflows_max;
	u8 status;

	struct work_struct work;
	};

	struct mptcp_data_frag {
	struct list_head list;
	u64 data_seq;
	int data_len;
	int offset;
	int overhead;
	struct page *page;
	};

	/* MPTCP connection sock */
	struct mptcp_sock {
	/* inet_connection_sock must be the first member */
	struct inet_connection_sock sk;
	u64 local_key;
	u64 remote_key;
	u64 write_seq;
	u64 ack_seq;
	atomic64_t snd_una;
	unsigned long timer_ival;
	u32 token;
	unsigned long flags;
	bool can_ack;
	spinlock_t join_list_lock;
	struct work_struct work;
	struct list_head conn_list;
	struct list_head rtx_queue;
	struct list_head join_list;
	struct skb_ext cached_ext; / for the next sendmsg */
	struct socket subflow; / outgoing connect/listener/!mp_capable */
	struct sock *first;
	struct mptcp_pm_data pm;
	};

	#define mptcp_for_each_subflow(__msk, __subflow) \
	list_for_each_entry(__subflow, &((__msk)->conn_list), node)

	static inline struct mptcp_sock mptcp_sk(const struct sock sk)
	{
	return (struct mptcp_sock *)sk;
	}

	static inline struct mptcp_data_frag mptcp_rtx_tail(const struct sock sk)
	{
	struct mptcp_sock *msk = mptcp_sk(sk);

	if (list_empty(&msk->rtx_queue))
	return NULL;

	return list_last_entry(&msk->rtx_queue, struct mptcp_data_frag, list);
	}

	static inline struct mptcp_data_frag mptcp_rtx_head(const struct sock sk)
	{
	struct mptcp_sock *msk = mptcp_sk(sk);

	return list_first_entry_or_null(&msk->rtx_queue, struct mptcp_data_frag, list);
	}

	struct mptcp_subflow_request_sock {
	struct tcp_request_sock sk;
	u16 mp_capable : 1,
	mp_join : 1,
	backup : 1;
	u8 local_id;
	u8 remote_id;
	u64 local_key;
	u64 idsn;
	u32 token;
	u32 ssn_offset;
	u64 thmac;
	u32 local_nonce;
	u32 remote_nonce;
	struct mptcp_sock *msk;
	};

	static inline struct mptcp_subflow_request_sock *
	mptcp_subflow_rsk(const struct request_sock *rsk)
	{
	return (struct mptcp_subflow_request_sock *)rsk;
	}

	/* MPTCP subflow context */
	struct mptcp_subflow_context {
	struct list_head node;/* conn_list of subflows */
	u64 local_key;
	u64 remote_key;
	u64 idsn;
	u64 map_seq;
	u32 snd_isn;
	u32 token;
	u32 rel_write_seq;
	u32 map_subflow_seq;
	u32 ssn_offset;
	u32 map_data_len;
	u32 request_mptcp : 1, /* send MP_CAPABLE */
	request_join : 1, /* send MP_JOIN */
	request_bkup : 1,
	mp_capable : 1, /* remote is MPTCP capable */
	mp_join : 1, /* remote is JOINing */
	fully_established : 1, /* path validated */
	pm_notified : 1, /* PM hook called for established status */
	conn_finished : 1,
	map_valid : 1,
	mpc_map : 1,
	backup : 1,
	data_avail : 1,
	rx_eof : 1,
	data_fin_tx_enable : 1,
	use_64bit_ack : 1, /* Set when we received a 64-bit DSN */
	can_ack : 1; /* only after processing the remote a key */
	u64 data_fin_tx_seq;
	u32 remote_nonce;
	u64 thmac;
	u32 local_nonce;
	u32 remote_token;
	u8 hmac[MPTCPOPT_HMAC_LEN];
	u8 local_id;
	u8 remote_id;

	struct sock tcp_sock; / tcp sk backpointer */
	struct sock conn; / parent mptcp_sock */
	const struct inet_connection_sock_af_ops *icsk_af_ops;
	void (tcp_data_ready)(struct sock sk);
	void (tcp_state_change)(struct sock sk);
	void (tcp_write_space)(struct sock sk);

	struct rcu_head rcu;
	};

	static inline struct mptcp_subflow_context *
	mptcp_subflow_ctx(const struct sock *sk)
	{
	struct inet_connection_sock *icsk = inet_csk(sk);

	/* Use RCU on icsk_ulp_data only for sock diag code */
	return (__force struct mptcp_subflow_context *)icsk->icsk_ulp_data;
	}

	static inline struct sock *
	mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
	{
	return subflow->tcp_sock;
	}

	static inline u64
	mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
	{
	return tcp_sk(mptcp_subflow_tcp_sock(subflow))->copied_seq -
	subflow->ssn_offset -
	subflow->map_subflow_seq;
	}

	static inline u64
	mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
	{
	return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
	}

	int mptcp_is_enabled(struct net *net);
	bool mptcp_subflow_data_available(struct sock *sk);
	void mptcp_subflow_init(void);

	/* called with sk socket lock held */
	int __mptcp_subflow_connect(struct sock *sk, int ifindex,
	const struct mptcp_addr_info *loc,
	const struct mptcp_addr_info *remote);
	int mptcp_subflow_create_socket(struct sock sk, struct socket *new_sock);

	static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
	struct mptcp_subflow_context *ctx)
	{
	sk->sk_data_ready = ctx->tcp_data_ready;
	sk->sk_state_change = ctx->tcp_state_change;
	sk->sk_write_space = ctx->tcp_write_space;

	inet_csk(sk)->icsk_af_ops = ctx->icsk_af_ops;
	}

	extern const struct inet_connection_sock_af_ops ipv4_specific;
	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
	extern const struct inet_connection_sock_af_ops ipv6_specific;
	#endif

	void mptcp_proto_init(void);
	#if IS_ENABLED(CONFIG_MPTCP_IPV6)
	int mptcp_proto_v6_init(void);
	#endif

	struct sock mptcp_sk_clone(const struct sock sk,
	const struct mptcp_options_received *mp_opt,
	struct request_sock *req);
	void mptcp_get_options(const struct sk_buff *skb,
	struct mptcp_options_received *mp_opt);

	void mptcp_finish_connect(struct sock *sk);
	void mptcp_data_ready(struct sock sk, struct sock ssk);
	bool mptcp_finish_join(struct sock *sk);
	void mptcp_data_acked(struct sock *sk);
	void mptcp_subflow_eof(struct sock *sk);

	int mptcp_token_new_request(struct request_sock *req);
	void mptcp_token_destroy_request(u32 token);
	int mptcp_token_new_connect(struct sock *sk);
	int mptcp_token_new_accept(u32 token, struct sock *conn);
	struct mptcp_sock *mptcp_token_get_sock(u32 token);
	void mptcp_token_destroy(u32 token);

	void mptcp_crypto_key_sha(u64 key, u32 token, u64 idsn);
	static inline void mptcp_crypto_key_gen_sha(u64 key, u32 token, u64 *idsn)
	{
	/* we might consider a faster version that computes the key as a
	* hash of some information available in the MPTCP socket. Use
	* random data at the moment, as it's probably the safest option
	* in case multiple sockets are opened in different namespaces at
	* the same time.
	*/
	get_random_bytes(key, sizeof(u64));
	mptcp_crypto_key_sha(*key, token, idsn);
	}

	void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 msg, int len, void hmac);

	void mptcp_pm_init(void);
	void mptcp_pm_data_init(struct mptcp_sock *msk);
	void mptcp_pm_close(struct mptcp_sock *msk);
	void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side);
	void mptcp_pm_fully_established(struct mptcp_sock *msk);
	bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
	void mptcp_pm_connection_closed(struct mptcp_sock *msk);
	void mptcp_pm_subflow_established(struct mptcp_sock *msk,
	struct mptcp_subflow_context *subflow);
	void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id);
	void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
	const struct mptcp_addr_info *addr);

	int mptcp_pm_announce_addr(struct mptcp_sock *msk,
	const struct mptcp_addr_info *addr);
	int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id);
	int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id);

	static inline bool mptcp_pm_should_signal(struct mptcp_sock *msk)
	{
	return READ_ONCE(msk->pm.addr_signal);
	}

	static inline unsigned int mptcp_add_addr_len(int family)
	{
	if (family == AF_INET)
	return TCPOLEN_MPTCP_ADD_ADDR;
	return TCPOLEN_MPTCP_ADD_ADDR6;
	}

	bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
	struct mptcp_addr_info *saddr);
	int mptcp_pm_get_local_id(struct mptcp_sock msk, struct sock_common skc);

	void mptcp_pm_nl_init(void);
	void mptcp_pm_nl_data_init(struct mptcp_sock *msk);
	void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
	void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
	void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk);
	int mptcp_pm_nl_get_local_id(struct mptcp_sock msk, struct sock_common skc);

	static inline struct mptcp_ext mptcp_get_ext(struct sk_buff skb)
	{
	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);
	}

	static inline bool before64(__u64 seq1, __u64 seq2)
	{
	return (__s64)(seq1 - seq2) < 0;
	}

	#define after64(seq2, seq1) before64(seq1, seq2)

	void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops);

	#endif /* __MPTCP_PROTOCOL_H */