linux/net/l2tp/l2tp_core.h

/* SPDX-License-Identifier: GPL-2.0-only */
/* L2TP internal definitions.
 *
 * Copyright (c) 2008,2009 Katalix Systems Ltd
 */
#include <linux/refcount.h>

#ifndef _L2TP_CORE_H_
#define _L2TP_CORE_H_

#include <net/dst.h>
#include <net/sock.h>

#ifdef CONFIG_XFRM
#include <net/xfrm.h>
#endif

/* Random numbers used for internal consistency checks of tunnel and session structures */
#define L2TP_TUNNEL_MAGIC …
#define L2TP_SESSION_MAGIC …

struct sk_buff;

struct l2tp_stats { … };

struct l2tp_tunnel;

/* L2TP session configuration */
struct l2tp_session_cfg { … };

struct l2tp_session_coll_list { … };

/* Represents a session (pseudowire) instance.
 * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
 * Is linked into a per-tunnel session list and a per-net ("global") IDR tree.
 */
#define L2TP_SESSION_NAME_MAX …
struct l2tp_session { … };

/* L2TP tunnel configuration */
struct l2tp_tunnel_cfg { … };

/* Represents a tunnel instance.
 * Tracks runtime state including IO statistics.
 * Holds the tunnel socket (either passed from userspace or directly created by the kernel).
 * Maintains a list of sessions belonging to the tunnel instance.
 * Is linked into a per-net list of tunnels.
 */
#define L2TP_TUNNEL_NAME_MAX …
struct l2tp_tunnel { … };

/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
struct l2tp_nl_cmd_ops { … };

static inline void *l2tp_session_priv(struct l2tp_session *session)
{ … }

/* Tunnel and session refcounts */
void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel);
void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel);
void l2tp_session_inc_refcount(struct l2tp_session *session);
void l2tp_session_dec_refcount(struct l2tp_session *session);

/* Tunnel and session lookup.
 * These functions take a reference on the instances they return, so
 * the caller must ensure that the reference is dropped appropriately.
 */
struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);

struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
				      u32 tunnel_id, u32 session_id);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
						const char *ifname);

/* Tunnel and session lifetime management.
 * Creation of a new instance is a two-step process: create, then register.
 * Destruction is triggered using the *_delete functions, and completes asynchronously.
 */
int l2tp_tunnel_create(int fd, int version, u32 tunnel_id,
		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
		       struct l2tp_tunnel **tunnelp);
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
			 struct l2tp_tunnel_cfg *cfg);
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);
int l2tp_session_register(struct l2tp_session *session,
			  struct l2tp_tunnel *tunnel);
void l2tp_session_delete(struct l2tp_session *session);

/* Receive path helpers.  If data sequencing is enabled for the session these
 * functions handle queuing and reordering prior to passing packets to the
 * pseudowire code to be passed to userspace.
 */
void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
		      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
		      int length);
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);

/* Transmit path helpers for sending packets over the tunnel socket. */
void l2tp_session_set_header_len(struct l2tp_session *session, int version);
int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb);

/* Pseudowire management.
 * Pseudowires should register with l2tp core on module init, and unregister
 * on module exit.
 */
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);

/* IOCTL helper for IP encap modules. */
int l2tp_ioctl(struct sock *sk, int cmd, int *karg);

/* Extract the tunnel structure from a socket's sk_user_data pointer,
 * validating the tunnel magic feather.
 */
struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk);

static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
{ … }

static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
{ … }

#ifdef CONFIG_XFRM
static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
{ … }
#else
static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
{
	return false;
}
#endif

static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
					       unsigned char **ptr, unsigned char **optr)
{ … }

#define MODULE_ALIAS_L2TP_PWTYPE(type) …

#endif /* _L2TP_CORE_H_ */