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Diffstat (limited to 'net/l2tp/l2tp_core.h')
| -rw-r--r-- | net/l2tp/l2tp_core.h | 346 |
1 files changed, 346 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h new file mode 100644 index 000000000..a88e070b4 --- /dev/null +++ b/net/l2tp/l2tp_core.h @@ -0,0 +1,346 @@ +/* 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 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, unsigned long arg); + +/* 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_ */ |