/* SPDX-License-Identifier: GPL-2.0-only */ /* L2TP internal definitions. * * Copyright (c) 2008,2009 Katalix Systems Ltd */ #include #ifndef _L2TP_CORE_H_ #define _L2TP_CORE_H_ #include #include #ifdef CONFIG_XFRM #include #endif /* Random numbers used for internal consistency checks of tunnel and session structures */ #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 BIT(L2TP_HASH_BITS) /* System-wide session hash table size */ #define L2TP_HASH_BITS_2 8 #define L2TP_HASH_SIZE_2 BIT(L2TP_HASH_BITS_2) 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; atomic_long_t rx_invalid; }; struct l2tp_tunnel; /* L2TP session configuration */ struct l2tp_session_cfg { enum l2tp_pwtype pw_type; 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 LNS control. */ 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) */ char *ifname; }; /* Represents a session (pseudowire) instance. * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics. * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into * an additional per-net ("global") hashlist. */ #define L2TP_SESSION_NAME_MAX 32 struct l2tp_session { int magic; /* should be L2TP_SESSION_MAGIC */ long dead; 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_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 */ refcount_t ref_count; char name[L2TP_SESSION_NAME_MAX]; /* for logging */ char ifname[IFNAMSIZ]; 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 LNS control. */ int reorder_timeout; /* configured reorder timeout (in jiffies) */ int reorder_skip; /* set if skip to next nr */ enum l2tp_pwtype pwtype; struct l2tp_stats stats; struct hlist_node global_hlist; /* global hash list node */ /* Session receive handler for data packets. * Each pseudowire implementation should implement this callback in order to * handle incoming packets. Packets are passed to the pseudowire handler after * reordering, if data sequence numbers are enabled for the session. */ void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len); /* Session close handler. * Each pseudowire implementation may implement this callback in order to carry * out pseudowire-specific shutdown actions. * The callback is called by core after unhashing the session and purging its * reorder queue. */ void (*session_close)(struct l2tp_session *session); /* Session show handler. * Pseudowire-specific implementation of debugfs session rendering. * The callback is called by l2tp_debugfs.c after rendering core session * information. */ void (*show)(struct seq_file *m, void *priv); u8 priv[]; /* private data */ }; /* L2TP tunnel configuration */ struct l2tp_tunnel_cfg { 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; }; /* 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 hashlist of sessions belonging to the tunnel instance. * Is linked into a per-net list of tunnels. */ #define L2TP_TUNNEL_NAME_MAX 20 struct l2tp_tunnel { int magic; /* Should be L2TP_TUNNEL_MAGIC */ unsigned long dead; struct rcu_head rcu; spinlock_t hlist_lock; /* write-protection for session_hlist */ bool acpt_newsess; /* indicates whether this tunnel accepts * new sessions. Protected by hlist_lock. */ 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[L2TP_TUNNEL_NAME_MAX]; /* for logging */ enum l2tp_encap_type encap; struct l2tp_stats stats; struct list_head list; /* list node on per-namespace list of tunnels */ struct net *l2tp_net; /* the net we belong to */ refcount_t ref_count; void (*old_sk_destruct)(struct sock *sk); struct sock *sock; /* parent socket */ int fd; /* parent fd, if tunnel socket was created * by userspace */ struct work_struct del_work; }; /* Pseudowire ops callbacks for use with the l2tp genetlink interface */ struct l2tp_nl_cmd_ops { /* The pseudowire session create callback is responsible for creating a session * instance for a specific pseudowire type. * It must call l2tp_session_create and l2tp_session_register to register the * session instance, as well as carry out any pseudowire-specific initialisation. * It must return >= 0 on success, or an appropriate negative errno value on failure. */ int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg); /* The pseudowire session delete callback is responsible for initiating the deletion * of a session instance. * It must call l2tp_session_delete, as well as carry out any pseudowire-specific * teardown actions. */ void (*session_delete)(struct l2tp_session *session); }; static inline void *l2tp_session_priv(struct l2tp_session *session) { return &session->priv[0]; } /* 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_tunnel_get_session(struct l2tp_tunnel *tunnel, u32 session_id); struct l2tp_session *l2tp_session_get(const struct net *net, 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) { switch (session->l2specific_type) { case L2TP_L2SPECTYPE_DEFAULT: return 4; case L2TP_L2SPECTYPE_NONE: default: return 0; } } static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel) { struct dst_entry *dst; u32 mtu; dst = sk_dst_get(tunnel->sock); if (!dst) return 0; mtu = dst_mtu(dst); dst_release(dst); return mtu; } #ifdef CONFIG_XFRM static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) { struct sock *sk = tunnel->sock; return sk && (rcu_access_pointer(sk->sk_policy[0]) || rcu_access_pointer(sk->sk_policy[1])); } #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) { 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 MODULE_ALIAS_L2TP_PWTYPE(type) \ MODULE_ALIAS("net-l2tp-type-" __stringify(type)) #endif /* _L2TP_CORE_H_ */