net/l2tp/l2tp_core.h - kernel/msm-4.9 - Gitiles

 /*
  * L2TP internal definitions.
  *
  * Copyright (c) 2008,2009 Katalix Systems Ltd
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #ifndef _L2TP_CORE_H_
 #define _L2TP_CORE_H_

 /* Just some random numbers */
 #define L2TP_TUNNEL_MAGIC	0x42114DDA
 #define L2TP_SESSION_MAGIC	0x0C04EB7D

 /* Per tunnel, session hash table size */
 #define L2TP_HASH_BITS	4
 #define L2TP_HASH_SIZE	(1 << L2TP_HASH_BITS)

 /* System-wide, session hash table size */
 #define L2TP_HASH_BITS_2	8
 #define L2TP_HASH_SIZE_2	(1 << L2TP_HASH_BITS_2)

 /* Debug message categories for the DEBUG socket option */
 enum {
 	L2TP_MSG_DEBUG		= (1 << 0),	/* verbose debug (if
 						 * compiled in) */
 	L2TP_MSG_CONTROL	= (1 << 1),	/* userspace - kernel
 						 * interface */
 	L2TP_MSG_SEQ		= (1 << 2),	/* sequence numbers */
 	L2TP_MSG_DATA		= (1 << 3),	/* data packets */
 };

 struct sk_buff;

 struct l2tp_stats {
 	atomic_long_t		tx_packets;
 	atomic_long_t		tx_bytes;
 	atomic_long_t		tx_errors;
 	atomic_long_t		rx_packets;
 	atomic_long_t		rx_bytes;
 	atomic_long_t		rx_seq_discards;
 	atomic_long_t		rx_oos_packets;
 	atomic_long_t		rx_errors;
 	atomic_long_t		rx_cookie_discards;
 };

 struct l2tp_tunnel;

 /* Describes a session. Contains information to determine incoming
  * packets and transmit outgoing ones.
  */
 struct l2tp_session_cfg {
 	enum l2tp_pwtype	pw_type;
 	unsigned int		data_seq:2;	/* data sequencing level
 						 * 0 => none, 1 => IP only,
 						 * 2 => all
 						 */
 	unsigned int		recv_seq:1;	/* expect receive packets with
 						 * sequence numbers? */
 	unsigned int		send_seq:1;	/* send packets with sequence
 						 * numbers? */
 	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
 						 * sequence numbers under
 						 * control of LNS. */
 	int			debug;		/* bitmask of debug message
 						 * categories */
 	u16			vlan_id;	/* VLAN pseudowire only */
 	u16			l2specific_len;	/* Layer 2 specific length */
 	u16			l2specific_type; /* Layer 2 specific type */
 	u8			cookie[8];	/* optional cookie */
 	int			cookie_len;	/* 0, 4 or 8 bytes */
 	u8			peer_cookie[8];	/* peer's cookie */
 	int			peer_cookie_len; /* 0, 4 or 8 bytes */
 	int			reorder_timeout; /* configured reorder timeout
 						  * (in jiffies) */
 	int			mtu;
 	int			mru;
 	char			*ifname;
 };

 struct l2tp_session {
 	int			magic;		/* should be
 						 * L2TP_SESSION_MAGIC */

 	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel
 						 * context */
 	u32			session_id;
 	u32			peer_session_id;
 	u8			cookie[8];
 	int			cookie_len;
 	u8			peer_cookie[8];
 	int			peer_cookie_len;
 	u16			l2specific_len;
 	u16			l2specific_type;
 	u16			hdr_len;
 	u32			nr;		/* session NR state (receive) */
 	u32			ns;		/* session NR state (send) */
 	struct sk_buff_head	reorder_q;	/* receive reorder queue */
 	u32			nr_max;		/* max NR. Depends on tunnel */
 	u32			nr_window_size;	/* NR window size */
 	u32			nr_oos;		/* NR of last OOS packet */
 	int			nr_oos_count;	/* For OOS recovery */
 	int			nr_oos_count_max;
 	struct hlist_node	hlist;		/* Hash list node */
 	atomic_t		ref_count;

 	char			name[32];	/* for logging */
 	char			ifname[IFNAMSIZ];
 	unsigned int		data_seq:2;	/* data sequencing level
 						 * 0 => none, 1 => IP only,
 						 * 2 => all
 						 */
 	unsigned int		recv_seq:1;	/* expect receive packets with
 						 * sequence numbers? */
 	unsigned int		send_seq:1;	/* send packets with sequence
 						 * numbers? */
 	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
 						 * sequence numbers under
 						 * control of LNS. */
 	int			debug;		/* bitmask of debug message
 						 * categories */
 	int			reorder_timeout; /* configured reorder timeout
 						  * (in jiffies) */
 	int			reorder_skip;	/* set if skip to next nr */
 	int			mtu;
 	int			mru;
 	enum l2tp_pwtype	pwtype;
 	struct l2tp_stats	stats;
 	struct hlist_node	global_hlist;	/* Global hash list node */

 	int (*build_header)(struct l2tp_session *session, void *buf);
 	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 	void (*session_close)(struct l2tp_session *session);
 	void (*ref)(struct l2tp_session *session);
 	void (*deref)(struct l2tp_session *session);
 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 	void (*show)(struct seq_file *m, void *priv);
 #endif
 	uint8_t			priv[0];	/* private data */
 };

 /* Describes the tunnel. It contains info to track all the associated
  * sessions so incoming packets can be sorted out
  */
 struct l2tp_tunnel_cfg {
 	int			debug;		/* bitmask of debug message
 						 * categories */
 	enum l2tp_encap_type	encap;

 	/* Used only for kernel-created sockets */
 	struct in_addr		local_ip;
 	struct in_addr		peer_ip;
 #if IS_ENABLED(CONFIG_IPV6)
 	struct in6_addr		*local_ip6;
 	struct in6_addr		*peer_ip6;
 #endif
 	u16			local_udp_port;
 	u16			peer_udp_port;
 	unsigned int		use_udp_checksums:1,
 				udp6_zero_tx_checksums:1,
 				udp6_zero_rx_checksums:1;
 };

 struct l2tp_tunnel {
 	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */

 	unsigned long		dead;

 	struct rcu_head rcu;
 	rwlock_t		hlist_lock;	/* protect session_hlist */
 	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
 						/* hashed list of sessions,
 						 * hashed by id */
 	u32			tunnel_id;
 	u32			peer_tunnel_id;
 	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */

 	char			name[20];	/* for logging */
 	int			debug;		/* bitmask of debug message
 						 * categories */
 	enum l2tp_encap_type	encap;
 	struct l2tp_stats	stats;

 	struct list_head	list;		/* Keep a list of all tunnels */
 	struct net		*l2tp_net;	/* the net we belong to */

 	atomic_t		ref_count;
 #ifdef CONFIG_DEBUG_FS
 	void (*show)(struct seq_file *m, void *arg);
 #endif
 	void (*old_sk_destruct)(struct sock *);
 	struct sock		*sock;		/* Parent socket */
 	int			fd;		/* Parent fd, if tunnel socket
 						 * was created by userspace */
 #if IS_ENABLED(CONFIG_IPV6)
 	bool			v4mapped;
 #endif

 	struct work_struct	del_work;

 	uint8_t			priv[0];	/* private data */
 };

 struct l2tp_nl_cmd_ops {
 	int (*session_create)(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
 	int (*session_delete)(struct l2tp_session *session);
 };

 static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
 {
 	return &tunnel->priv[0];
 }

 static inline void *l2tp_session_priv(struct l2tp_session *session)
 {
 	return &session->priv[0];
 }

 static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
 {
 	struct l2tp_tunnel *tunnel;

 	if (sk == NULL)
 		return NULL;

 	sock_hold(sk);
 	tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
 	if (tunnel == NULL) {
 		sock_put(sk);
 		goto out;
 	}

 	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

 out:
 	return tunnel;
 }

 struct l2tp_session *l2tp_session_get(struct net *net,
 				      struct l2tp_tunnel *tunnel,
 				      u32 session_id, bool do_ref);
 struct l2tp_session *l2tp_session_find(struct net *net,
 				       struct l2tp_tunnel *tunnel,
 				       u32 session_id);
 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 					  bool do_ref);
 struct l2tp_session *l2tp_session_get_by_ifname(struct net *net, char *ifname,
 						bool do_ref);
 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);

 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 		       struct l2tp_tunnel **tunnelp);
 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 struct l2tp_session *l2tp_session_create(int priv_size,
 					 struct l2tp_tunnel *tunnel,
 					 u32 session_id, u32 peer_session_id,
 					 struct l2tp_session_cfg *cfg);
 void __l2tp_session_unhash(struct l2tp_session *session);
 int l2tp_session_delete(struct l2tp_session *session);
 void l2tp_session_free(struct l2tp_session *session);
 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 		      int length);
 int l2tp_session_queue_purge(struct l2tp_session *session);
 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 void l2tp_session_set_header_len(struct l2tp_session *session, int version);

 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 		  int hdr_len);

 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 			 const struct l2tp_nl_cmd_ops *ops);
 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);

 /* Session reference counts. Incremented when code obtains a reference
  * to a session.
  */
 static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
 {
 	atomic_inc(&session->ref_count);
 }

 static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
 {
 	if (atomic_dec_and_test(&session->ref_count))
 		l2tp_session_free(session);
 }

 #ifdef L2TP_REFCNT_DEBUG
 #define l2tp_session_inc_refcount(_s)					\
 do {									\
 	pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n",	\
 		 __func__, __LINE__, (_s)->name,			\
 		 atomic_read(&_s->ref_count));				\
 	l2tp_session_inc_refcount_1(_s);				\
 } while (0)
 #define l2tp_session_dec_refcount(_s)					\
 do {									\
 	pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n",	\
 		 __func__, __LINE__, (_s)->name,			\
 		 atomic_read(&_s->ref_count));				\
 	l2tp_session_dec_refcount_1(_s);				\
 } while (0)
 #else
 #define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
 #define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
 #endif

 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 {
 	switch (session->l2specific_type) {
 	case L2TP_L2SPECTYPE_DEFAULT:
 		return 4;
 	case L2TP_L2SPECTYPE_NONE:
 	default:
 		return 0;
 	}
 }

 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 					       unsigned char **ptr, unsigned char **optr)
 {
 	int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);

 	if (opt_len > 0) {
 		int off = *ptr - *optr;

 		if (!pskb_may_pull(skb, off + opt_len))
 			return -1;

 		if (skb->data != *optr) {
 			*optr = skb->data;
 			*ptr = skb->data + off;
 		}
 	}

 	return 0;
 }

 #define l2tp_printk(ptr, type, func, fmt, ...)				\
 do {									\
 	if (((ptr)->debug) & (type))					\
 		func(fmt, ##__VA_ARGS__);				\
 } while (0)

 #define l2tp_warn(ptr, type, fmt, ...)					\
 	l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
 #define l2tp_info(ptr, type, fmt, ...)					\
 	l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
 #define l2tp_dbg(ptr, type, fmt, ...)					\
 	l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)

 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 	MODULE_ALIAS("net-l2tp-type-" __stringify(type))

 #endif /* _L2TP_CORE_H_ */
	/*
	* L2TP internal definitions.
	*
	* Copyright (c) 2008,2009 Katalix Systems Ltd
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#ifndef _L2TP_CORE_H_
	#define _L2TP_CORE_H_

	/* Just some random numbers */
	#define L2TP_TUNNEL_MAGIC 0x42114DDA
	#define L2TP_SESSION_MAGIC 0x0C04EB7D

	/* Per tunnel, session hash table size */
	#define L2TP_HASH_BITS 4
	#define L2TP_HASH_SIZE (1 << L2TP_HASH_BITS)

	/* System-wide, session hash table size */
	#define L2TP_HASH_BITS_2 8
	#define L2TP_HASH_SIZE_2 (1 << L2TP_HASH_BITS_2)

	/* Debug message categories for the DEBUG socket option */
	enum {
	L2TP_MSG_DEBUG = (1 << 0), /* verbose debug (if
	* compiled in) */
	L2TP_MSG_CONTROL = (1 << 1), /* userspace - kernel
	* interface */
	L2TP_MSG_SEQ = (1 << 2), /* sequence numbers */
	L2TP_MSG_DATA = (1 << 3), /* data packets */
	};

	struct sk_buff;

	struct l2tp_stats {
	atomic_long_t tx_packets;
	atomic_long_t tx_bytes;
	atomic_long_t tx_errors;
	atomic_long_t rx_packets;
	atomic_long_t rx_bytes;
	atomic_long_t rx_seq_discards;
	atomic_long_t rx_oos_packets;
	atomic_long_t rx_errors;
	atomic_long_t rx_cookie_discards;
	};

	struct l2tp_tunnel;

	/* Describes a session. Contains information to determine incoming
	* packets and transmit outgoing ones.
	*/
	struct l2tp_session_cfg {
	enum l2tp_pwtype pw_type;
	unsigned int data_seq:2; /* data sequencing level
	* 0 => none, 1 => IP only,
	* 2 => all
	*/
	unsigned int recv_seq:1; /* expect receive packets with
	* sequence numbers? */
	unsigned int send_seq:1; /* send packets with sequence
	* numbers? */
	unsigned int lns_mode:1; /* behave as LNS? LAC enables
	* sequence numbers under
	* control of LNS. */
	int debug; /* bitmask of debug message
	* categories */
	u16 vlan_id; /* VLAN pseudowire only */
	u16 l2specific_len; /* Layer 2 specific length */
	u16 l2specific_type; /* Layer 2 specific type */
	u8 cookie[8]; /* optional cookie */
	int cookie_len; /* 0, 4 or 8 bytes */
	u8 peer_cookie[8]; /* peer's cookie */
	int peer_cookie_len; /* 0, 4 or 8 bytes */
	int reorder_timeout; /* configured reorder timeout
	* (in jiffies) */
	int mtu;
	int mru;
	char *ifname;
	};

	struct l2tp_session {
	int magic; /* should be
	* L2TP_SESSION_MAGIC */

	struct l2tp_tunnel tunnel; / back pointer to tunnel
	* context */
	u32 session_id;
	u32 peer_session_id;
	u8 cookie[8];
	int cookie_len;
	u8 peer_cookie[8];
	int peer_cookie_len;
	u16 l2specific_len;
	u16 l2specific_type;
	u16 hdr_len;
	u32 nr; /* session NR state (receive) */
	u32 ns; /* session NR state (send) */
	struct sk_buff_head reorder_q; /* receive reorder queue */
	u32 nr_max; /* max NR. Depends on tunnel */
	u32 nr_window_size; /* NR window size */
	u32 nr_oos; /* NR of last OOS packet */
	int nr_oos_count; /* For OOS recovery */
	int nr_oos_count_max;
	struct hlist_node hlist; /* Hash list node */
	atomic_t ref_count;

	char name[32]; /* for logging */
	char ifname[IFNAMSIZ];
	unsigned int data_seq:2; /* data sequencing level
	* 0 => none, 1 => IP only,
	* 2 => all
	*/
	unsigned int recv_seq:1; /* expect receive packets with
	* sequence numbers? */
	unsigned int send_seq:1; /* send packets with sequence
	* numbers? */
	unsigned int lns_mode:1; /* behave as LNS? LAC enables
	* sequence numbers under
	* control of LNS. */
	int debug; /* bitmask of debug message
	* categories */
	int reorder_timeout; /* configured reorder timeout
	* (in jiffies) */
	int reorder_skip; /* set if skip to next nr */
	int mtu;
	int mru;
	enum l2tp_pwtype pwtype;
	struct l2tp_stats stats;
	struct hlist_node global_hlist; /* Global hash list node */

	int (build_header)(struct l2tp_session session, void *buf);
	void (recv_skb)(struct l2tp_session session, struct sk_buff *skb, int data_len);
	void (session_close)(struct l2tp_session session);
	void (ref)(struct l2tp_session session);
	void (deref)(struct l2tp_session session);
	#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
	void (show)(struct seq_file m, void *priv);
	#endif
	uint8_t priv[0]; /* private data */
	};

	/* Describes the tunnel. It contains info to track all the associated
	* sessions so incoming packets can be sorted out
	*/
	struct l2tp_tunnel_cfg {
	int debug; /* bitmask of debug message
	* categories */
	enum l2tp_encap_type encap;

	/* Used only for kernel-created sockets */
	struct in_addr local_ip;
	struct in_addr peer_ip;
	#if IS_ENABLED(CONFIG_IPV6)
	struct in6_addr *local_ip6;
	struct in6_addr *peer_ip6;
	#endif
	u16 local_udp_port;
	u16 peer_udp_port;
	unsigned int use_udp_checksums:1,
	udp6_zero_tx_checksums:1,
	udp6_zero_rx_checksums:1;
	};

	struct l2tp_tunnel {
	int magic; /* Should be L2TP_TUNNEL_MAGIC */

	unsigned long dead;

	struct rcu_head rcu;
	rwlock_t hlist_lock; /* protect session_hlist */
	struct hlist_head session_hlist[L2TP_HASH_SIZE];
	/* hashed list of sessions,
	* hashed by id */
	u32 tunnel_id;
	u32 peer_tunnel_id;
	int version; /* 2=>L2TPv2, 3=>L2TPv3 */

	char name[20]; /* for logging */
	int debug; /* bitmask of debug message
	* categories */
	enum l2tp_encap_type encap;
	struct l2tp_stats stats;

	struct list_head list; /* Keep a list of all tunnels */
	struct net l2tp_net; / the net we belong to */

	atomic_t ref_count;
	#ifdef CONFIG_DEBUG_FS
	void (show)(struct seq_file m, void *arg);
	#endif
	void (old_sk_destruct)(struct sock );
	struct sock sock; / Parent socket */
	int fd; /* Parent fd, if tunnel socket
	* was created by userspace */
	#if IS_ENABLED(CONFIG_IPV6)
	bool v4mapped;
	#endif

	struct work_struct del_work;

	uint8_t priv[0]; /* private data */
	};

	struct l2tp_nl_cmd_ops {
	int (session_create)(struct net net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
	int (session_delete)(struct l2tp_session session);
	};

	static inline void l2tp_tunnel_priv(struct l2tp_tunnel tunnel)
	{
	return &tunnel->priv[0];
	}

	static inline void l2tp_session_priv(struct l2tp_session session)
	{
	return &session->priv[0];
	}

	static inline struct l2tp_tunnel l2tp_sock_to_tunnel(struct sock sk)
	{
	struct l2tp_tunnel *tunnel;

	if (sk == NULL)
	return NULL;

	sock_hold(sk);
	tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
	if (tunnel == NULL) {
	sock_put(sk);
	goto out;
	}

	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

	out:
	return tunnel;
	}

	struct l2tp_session l2tp_session_get(struct net net,
	struct l2tp_tunnel *tunnel,
	u32 session_id, bool do_ref);
	struct l2tp_session l2tp_session_find(struct net net,
	struct l2tp_tunnel *tunnel,
	u32 session_id);
	struct l2tp_session l2tp_session_get_nth(struct l2tp_tunnel tunnel, int nth,
	bool do_ref);
	struct l2tp_session l2tp_session_get_by_ifname(struct net net, char *ifname,
	bool do_ref);
	struct l2tp_tunnel l2tp_tunnel_find(struct net net, u32 tunnel_id);
	struct l2tp_tunnel l2tp_tunnel_find_nth(struct net net, int nth);

	int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
	u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
	struct l2tp_tunnel **tunnelp);
	void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
	void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
	struct l2tp_session *l2tp_session_create(int priv_size,
	struct l2tp_tunnel *tunnel,
	u32 session_id, u32 peer_session_id,
	struct l2tp_session_cfg *cfg);
	void __l2tp_session_unhash(struct l2tp_session *session);
	int l2tp_session_delete(struct l2tp_session *session);
	void l2tp_session_free(struct l2tp_session *session);
	void l2tp_recv_common(struct l2tp_session session, struct sk_buff skb,
	unsigned char ptr, unsigned char optr, u16 hdrflags,
	int length);
	int l2tp_session_queue_purge(struct l2tp_session *session);
	int l2tp_udp_encap_recv(struct sock sk, struct sk_buff skb);
	void l2tp_session_set_header_len(struct l2tp_session *session, int version);

	int l2tp_xmit_skb(struct l2tp_session session, struct sk_buff skb,
	int hdr_len);

	int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
	const struct l2tp_nl_cmd_ops *ops);
	void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
	int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);

	/* Session reference counts. Incremented when code obtains a reference
	* to a session.
	*/
	static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
	{
	atomic_inc(&session->ref_count);
	}

	static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
	{
	if (atomic_dec_and_test(&session->ref_count))
	l2tp_session_free(session);
	}

	#ifdef L2TP_REFCNT_DEBUG
	#define l2tp_session_inc_refcount(_s) \
	do { \
	pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", \
	__func__, __LINE__, (_s)->name, \
	atomic_read(&_s->ref_count)); \
	l2tp_session_inc_refcount_1(_s); \
	} while (0)
	#define l2tp_session_dec_refcount(_s) \
	do { \
	pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", \
	__func__, __LINE__, (_s)->name, \
	atomic_read(&_s->ref_count)); \
	l2tp_session_dec_refcount_1(_s); \
	} while (0)
	#else
	#define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
	#define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
	#endif

	static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
	{
	switch (session->l2specific_type) {
	case L2TP_L2SPECTYPE_DEFAULT:
	return 4;
	case L2TP_L2SPECTYPE_NONE:
	default:
	return 0;
	}
	}

	static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session session, struct sk_buff skb,
	unsigned char ptr, unsigned char optr)
	{
	int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);

	if (opt_len > 0) {
	int off = ptr - optr;

	if (!pskb_may_pull(skb, off + opt_len))
	return -1;

	if (skb->data != *optr) {
	*optr = skb->data;
	*ptr = skb->data + off;
	}
	}

	return 0;
	}

	#define l2tp_printk(ptr, type, func, fmt, ...) \
	do { \
	if (((ptr)->debug) & (type)) \
	func(fmt, ##__VA_ARGS__); \
	} while (0)

	#define l2tp_warn(ptr, type, fmt, ...) \
	l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
	#define l2tp_info(ptr, type, fmt, ...) \
	l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
	#define l2tp_dbg(ptr, type, fmt, ...) \
	l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)

	#define MODULE_ALIAS_L2TP_PWTYPE(type) \
	MODULE_ALIAS("net-l2tp-type-" __stringify(type))

	#endif /* _L2TP_CORE_H_ */