347 lines
11 KiB
C
347 lines
11 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* L2TP internal definitions.
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*
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* Copyright (c) 2008,2009 Katalix Systems Ltd
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*/
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#include <linux/refcount.h>
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#ifndef _L2TP_CORE_H_
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#define _L2TP_CORE_H_
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#include <net/dst.h>
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#include <net/sock.h>
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#ifdef CONFIG_XFRM
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#include <net/xfrm.h>
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#endif
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/* Random numbers used for internal consistency checks of tunnel and session structures */
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#define L2TP_TUNNEL_MAGIC 0x42114DDA
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#define L2TP_SESSION_MAGIC 0x0C04EB7D
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/* Per tunnel session hash table size */
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#define L2TP_HASH_BITS 4
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#define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS)
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/* System-wide session hash table size */
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#define L2TP_HASH_BITS_2 8
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#define L2TP_HASH_SIZE_2 BIT(L2TP_HASH_BITS_2)
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struct sk_buff;
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struct l2tp_stats {
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atomic_long_t tx_packets;
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atomic_long_t tx_bytes;
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atomic_long_t tx_errors;
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atomic_long_t rx_packets;
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atomic_long_t rx_bytes;
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atomic_long_t rx_seq_discards;
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atomic_long_t rx_oos_packets;
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atomic_long_t rx_errors;
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atomic_long_t rx_cookie_discards;
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atomic_long_t rx_invalid;
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};
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struct l2tp_tunnel;
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/* L2TP session configuration */
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struct l2tp_session_cfg {
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enum l2tp_pwtype pw_type;
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unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
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unsigned int send_seq:1; /* send packets with sequence numbers? */
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unsigned int lns_mode:1; /* behave as LNS?
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* LAC enables sequence numbers under LNS control.
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*/
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u16 l2specific_type; /* Layer 2 specific type */
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u8 cookie[8]; /* optional cookie */
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int cookie_len; /* 0, 4 or 8 bytes */
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u8 peer_cookie[8]; /* peer's cookie */
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int peer_cookie_len; /* 0, 4 or 8 bytes */
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int reorder_timeout; /* configured reorder timeout (in jiffies) */
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char *ifname;
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};
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/* Represents a session (pseudowire) instance.
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* Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
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* Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
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* an additional per-net ("global") hashlist.
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*/
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#define L2TP_SESSION_NAME_MAX 32
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struct l2tp_session {
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int magic; /* should be L2TP_SESSION_MAGIC */
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long dead;
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struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */
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u32 session_id;
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u32 peer_session_id;
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u8 cookie[8];
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int cookie_len;
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u8 peer_cookie[8];
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int peer_cookie_len;
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u16 l2specific_type;
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u16 hdr_len;
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u32 nr; /* session NR state (receive) */
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u32 ns; /* session NR state (send) */
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struct sk_buff_head reorder_q; /* receive reorder queue */
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u32 nr_max; /* max NR. Depends on tunnel */
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u32 nr_window_size; /* NR window size */
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u32 nr_oos; /* NR of last OOS packet */
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int nr_oos_count; /* for OOS recovery */
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int nr_oos_count_max;
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struct hlist_node hlist; /* hash list node */
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refcount_t ref_count;
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char name[L2TP_SESSION_NAME_MAX]; /* for logging */
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char ifname[IFNAMSIZ];
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unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
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unsigned int send_seq:1; /* send packets with sequence numbers? */
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unsigned int lns_mode:1; /* behave as LNS?
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* LAC enables sequence numbers under LNS control.
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*/
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int reorder_timeout; /* configured reorder timeout (in jiffies) */
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int reorder_skip; /* set if skip to next nr */
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enum l2tp_pwtype pwtype;
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struct l2tp_stats stats;
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struct hlist_node global_hlist; /* global hash list node */
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/* Session receive handler for data packets.
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* Each pseudowire implementation should implement this callback in order to
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* handle incoming packets. Packets are passed to the pseudowire handler after
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* reordering, if data sequence numbers are enabled for the session.
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*/
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void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
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/* Session close handler.
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* Each pseudowire implementation may implement this callback in order to carry
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* out pseudowire-specific shutdown actions.
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* The callback is called by core after unhashing the session and purging its
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* reorder queue.
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*/
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void (*session_close)(struct l2tp_session *session);
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/* Session show handler.
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* Pseudowire-specific implementation of debugfs session rendering.
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* The callback is called by l2tp_debugfs.c after rendering core session
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* information.
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*/
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void (*show)(struct seq_file *m, void *priv);
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u8 priv[]; /* private data */
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};
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/* L2TP tunnel configuration */
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struct l2tp_tunnel_cfg {
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enum l2tp_encap_type encap;
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/* Used only for kernel-created sockets */
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struct in_addr local_ip;
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struct in_addr peer_ip;
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#if IS_ENABLED(CONFIG_IPV6)
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struct in6_addr *local_ip6;
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struct in6_addr *peer_ip6;
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#endif
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u16 local_udp_port;
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u16 peer_udp_port;
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unsigned int use_udp_checksums:1,
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udp6_zero_tx_checksums:1,
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udp6_zero_rx_checksums:1;
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};
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/* Represents a tunnel instance.
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* Tracks runtime state including IO statistics.
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* Holds the tunnel socket (either passed from userspace or directly created by the kernel).
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* Maintains a hashlist of sessions belonging to the tunnel instance.
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* Is linked into a per-net list of tunnels.
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*/
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#define L2TP_TUNNEL_NAME_MAX 20
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struct l2tp_tunnel {
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int magic; /* Should be L2TP_TUNNEL_MAGIC */
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unsigned long dead;
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struct rcu_head rcu;
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spinlock_t hlist_lock; /* write-protection for session_hlist */
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bool acpt_newsess; /* indicates whether this tunnel accepts
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* new sessions. Protected by hlist_lock.
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*/
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struct hlist_head session_hlist[L2TP_HASH_SIZE];
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/* hashed list of sessions, hashed by id */
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u32 tunnel_id;
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u32 peer_tunnel_id;
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int version; /* 2=>L2TPv2, 3=>L2TPv3 */
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char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */
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enum l2tp_encap_type encap;
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struct l2tp_stats stats;
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struct list_head list; /* list node on per-namespace list of tunnels */
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struct net *l2tp_net; /* the net we belong to */
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refcount_t ref_count;
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void (*old_sk_destruct)(struct sock *sk);
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struct sock *sock; /* parent socket */
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int fd; /* parent fd, if tunnel socket was created
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* by userspace
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*/
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struct work_struct del_work;
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};
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/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
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struct l2tp_nl_cmd_ops {
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/* The pseudowire session create callback is responsible for creating a session
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* instance for a specific pseudowire type.
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* It must call l2tp_session_create and l2tp_session_register to register the
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* session instance, as well as carry out any pseudowire-specific initialisation.
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* It must return >= 0 on success, or an appropriate negative errno value on failure.
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*/
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int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
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u32 session_id, u32 peer_session_id,
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struct l2tp_session_cfg *cfg);
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/* The pseudowire session delete callback is responsible for initiating the deletion
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* of a session instance.
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* It must call l2tp_session_delete, as well as carry out any pseudowire-specific
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* teardown actions.
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*/
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void (*session_delete)(struct l2tp_session *session);
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};
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static inline void *l2tp_session_priv(struct l2tp_session *session)
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{
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return &session->priv[0];
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}
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/* Tunnel and session refcounts */
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void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel);
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void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel);
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void l2tp_session_inc_refcount(struct l2tp_session *session);
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void l2tp_session_dec_refcount(struct l2tp_session *session);
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/* Tunnel and session lookup.
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* These functions take a reference on the instances they return, so
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* the caller must ensure that the reference is dropped appropriately.
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*/
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struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
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struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
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struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
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u32 session_id);
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struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
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struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
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struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
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const char *ifname);
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/* Tunnel and session lifetime management.
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* Creation of a new instance is a two-step process: create, then register.
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* Destruction is triggered using the *_delete functions, and completes asynchronously.
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*/
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int l2tp_tunnel_create(int fd, int version, u32 tunnel_id,
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u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
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struct l2tp_tunnel **tunnelp);
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int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
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struct l2tp_tunnel_cfg *cfg);
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void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
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struct l2tp_session *l2tp_session_create(int priv_size,
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struct l2tp_tunnel *tunnel,
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u32 session_id, u32 peer_session_id,
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struct l2tp_session_cfg *cfg);
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int l2tp_session_register(struct l2tp_session *session,
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struct l2tp_tunnel *tunnel);
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void l2tp_session_delete(struct l2tp_session *session);
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/* Receive path helpers. If data sequencing is enabled for the session these
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* functions handle queuing and reordering prior to passing packets to the
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* pseudowire code to be passed to userspace.
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*/
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void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
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unsigned char *ptr, unsigned char *optr, u16 hdrflags,
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int length);
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int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
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/* Transmit path helpers for sending packets over the tunnel socket. */
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void l2tp_session_set_header_len(struct l2tp_session *session, int version);
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int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb);
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/* Pseudowire management.
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* Pseudowires should register with l2tp core on module init, and unregister
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* on module exit.
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*/
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int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
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void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
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/* IOCTL helper for IP encap modules. */
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int l2tp_ioctl(struct sock *sk, int cmd, int *karg);
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/* Extract the tunnel structure from a socket's sk_user_data pointer,
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* validating the tunnel magic feather.
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*/
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struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk);
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static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
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{
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switch (session->l2specific_type) {
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case L2TP_L2SPECTYPE_DEFAULT:
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return 4;
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case L2TP_L2SPECTYPE_NONE:
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default:
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return 0;
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}
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}
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static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
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{
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struct dst_entry *dst;
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u32 mtu;
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dst = sk_dst_get(tunnel->sock);
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if (!dst)
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return 0;
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mtu = dst_mtu(dst);
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dst_release(dst);
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return mtu;
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}
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#ifdef CONFIG_XFRM
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static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
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{
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struct sock *sk = tunnel->sock;
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return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
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rcu_access_pointer(sk->sk_policy[1]));
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}
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#else
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static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
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{
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return false;
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}
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#endif
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static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
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unsigned char **ptr, unsigned char **optr)
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{
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int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
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if (opt_len > 0) {
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int off = *ptr - *optr;
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if (!pskb_may_pull(skb, off + opt_len))
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return -1;
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if (skb->data != *optr) {
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*optr = skb->data;
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*ptr = skb->data + off;
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}
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}
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return 0;
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}
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#define MODULE_ALIAS_L2TP_PWTYPE(type) \
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MODULE_ALIAS("net-l2tp-type-" __stringify(type))
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#endif /* _L2TP_CORE_H_ */
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