1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /* L2TP internal definitions.
4 * Copyright (c) 2008,2009 Katalix Systems Ltd
6 #include <linux/refcount.h>
18 /* Random numbers used for internal consistency checks of tunnel and session structures */
19 #define L2TP_TUNNEL_MAGIC 0x42114DDA
20 #define L2TP_SESSION_MAGIC 0x0C04EB7D
22 /* Per tunnel session hash table size */
23 #define L2TP_HASH_BITS 4
24 #define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS)
26 /* System-wide session hash table size */
27 #define L2TP_HASH_BITS_2 8
28 #define L2TP_HASH_SIZE_2 BIT(L2TP_HASH_BITS_2)
33 atomic_long_t tx_packets;
34 atomic_long_t tx_bytes;
35 atomic_long_t tx_errors;
36 atomic_long_t rx_packets;
37 atomic_long_t rx_bytes;
38 atomic_long_t rx_seq_discards;
39 atomic_long_t rx_oos_packets;
40 atomic_long_t rx_errors;
41 atomic_long_t rx_cookie_discards;
46 /* L2TP session configuration */
47 struct l2tp_session_cfg {
48 enum l2tp_pwtype pw_type;
49 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
50 unsigned int send_seq:1; /* send packets with sequence numbers? */
51 unsigned int lns_mode:1; /* behave as LNS?
52 * LAC enables sequence numbers under LNS control.
54 int debug; /* bitmask of debug message categories */
55 u16 l2specific_type; /* Layer 2 specific type */
56 u8 cookie[8]; /* optional cookie */
57 int cookie_len; /* 0, 4 or 8 bytes */
58 u8 peer_cookie[8]; /* peer's cookie */
59 int peer_cookie_len; /* 0, 4 or 8 bytes */
60 int reorder_timeout; /* configured reorder timeout (in jiffies) */
64 /* Represents a session (pseudowire) instance.
65 * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
66 * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
67 * an additional per-net ("global") hashlist.
70 int magic; /* should be L2TP_SESSION_MAGIC */
73 struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */
82 u32 nr; /* session NR state (receive) */
83 u32 ns; /* session NR state (send) */
84 struct sk_buff_head reorder_q; /* receive reorder queue */
85 u32 nr_max; /* max NR. Depends on tunnel */
86 u32 nr_window_size; /* NR window size */
87 u32 nr_oos; /* NR of last OOS packet */
88 int nr_oos_count; /* for OOS recovery */
90 struct hlist_node hlist; /* hash list node */
93 char name[32]; /* for logging */
94 char ifname[IFNAMSIZ];
95 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
96 unsigned int send_seq:1; /* send packets with sequence numbers? */
97 unsigned int lns_mode:1; /* behave as LNS?
98 * LAC enables sequence numbers under LNS control.
100 int debug; /* bitmask of debug message categories */
101 int reorder_timeout; /* configured reorder timeout (in jiffies) */
102 int reorder_skip; /* set if skip to next nr */
103 enum l2tp_pwtype pwtype;
104 struct l2tp_stats stats;
105 struct hlist_node global_hlist; /* global hash list node */
107 /* Session receive handler for data packets.
108 * Each pseudowire implementation should implement this callback in order to
109 * handle incoming packets. Packets are passed to the pseudowire handler after
110 * reordering, if data sequence numbers are enabled for the session.
112 void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
114 /* Session close handler.
115 * Each pseudowire implementation may implement this callback in order to carry
116 * out pseudowire-specific shutdown actions.
117 * The callback is called by core after unhashing the session and purging its
120 void (*session_close)(struct l2tp_session *session);
122 /* Session show handler.
123 * Pseudowire-specific implementation of debugfs session rendering.
124 * The callback is called by l2tp_debugfs.c after rendering core session
127 void (*show)(struct seq_file *m, void *priv);
129 u8 priv[]; /* private data */
132 /* L2TP tunnel configuration */
133 struct l2tp_tunnel_cfg {
134 int debug; /* bitmask of debug message categories */
135 enum l2tp_encap_type encap;
137 /* Used only for kernel-created sockets */
138 struct in_addr local_ip;
139 struct in_addr peer_ip;
140 #if IS_ENABLED(CONFIG_IPV6)
141 struct in6_addr *local_ip6;
142 struct in6_addr *peer_ip6;
146 unsigned int use_udp_checksums:1,
147 udp6_zero_tx_checksums:1,
148 udp6_zero_rx_checksums:1;
151 /* Represents a tunnel instance.
152 * Tracks runtime state including IO statistics.
153 * Holds the tunnel socket (either passed from userspace or directly created by the kernel).
154 * Maintains a hashlist of sessions belonging to the tunnel instance.
155 * Is linked into a per-net list of tunnels.
158 int magic; /* Should be L2TP_TUNNEL_MAGIC */
163 rwlock_t hlist_lock; /* protect session_hlist */
164 bool acpt_newsess; /* indicates whether this tunnel accepts
165 * new sessions. Protected by hlist_lock.
167 struct hlist_head session_hlist[L2TP_HASH_SIZE];
168 /* hashed list of sessions, hashed by id */
171 int version; /* 2=>L2TPv2, 3=>L2TPv3 */
173 char name[20]; /* for logging */
174 int debug; /* bitmask of debug message categories */
175 enum l2tp_encap_type encap;
176 struct l2tp_stats stats;
178 struct list_head list; /* list node on per-namespace list of tunnels */
179 struct net *l2tp_net; /* the net we belong to */
181 refcount_t ref_count;
182 void (*old_sk_destruct)(struct sock *sk);
183 struct sock *sock; /* parent socket */
184 int fd; /* parent fd, if tunnel socket was created
188 struct work_struct del_work;
191 /* Pseudowire ops callbacks for use with the l2tp genetlink interface */
192 struct l2tp_nl_cmd_ops {
193 /* The pseudowire session create callback is responsible for creating a session
194 * instance for a specific pseudowire type.
195 * It must call l2tp_session_create and l2tp_session_register to register the
196 * session instance, as well as carry out any pseudowire-specific initialisation.
197 * It must return >= 0 on success, or an appropriate negative errno value on failure.
199 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
200 u32 session_id, u32 peer_session_id,
201 struct l2tp_session_cfg *cfg);
203 /* The pseudowire session delete callback is responsible for initiating the deletion
204 * of a session instance.
205 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific
208 void (*session_delete)(struct l2tp_session *session);
211 static inline void *l2tp_session_priv(struct l2tp_session *session)
213 return &session->priv[0];
216 /* Tunnel and session refcounts */
217 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel);
218 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel);
219 void l2tp_session_inc_refcount(struct l2tp_session *session);
220 void l2tp_session_dec_refcount(struct l2tp_session *session);
222 /* Tunnel and session lookup.
223 * These functions take a reference on the instances they return, so
224 * the caller must ensure that the reference is dropped appropriately.
226 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
227 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
228 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
231 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
232 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
233 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
236 /* Tunnel and session lifetime management.
237 * Creation of a new instance is a two-step process: create, then register.
238 * Destruction is triggered using the *_delete functions, and completes asynchronously.
240 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
241 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
242 struct l2tp_tunnel **tunnelp);
243 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
244 struct l2tp_tunnel_cfg *cfg);
245 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
247 struct l2tp_session *l2tp_session_create(int priv_size,
248 struct l2tp_tunnel *tunnel,
249 u32 session_id, u32 peer_session_id,
250 struct l2tp_session_cfg *cfg);
251 int l2tp_session_register(struct l2tp_session *session,
252 struct l2tp_tunnel *tunnel);
253 void l2tp_session_delete(struct l2tp_session *session);
255 /* Receive path helpers. If data sequencing is enabled for the session these
256 * functions handle queuing and reordering prior to passing packets to the
257 * pseudowire code to be passed to userspace.
259 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
260 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
262 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
264 /* Transmit path helpers for sending packets over the tunnel socket. */
265 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
266 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
269 /* Pseudowire management.
270 * Pseudowires should register with l2tp core on module init, and unregister
273 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
274 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
276 /* IOCTL helper for IP encap modules. */
277 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
279 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
281 switch (session->l2specific_type) {
282 case L2TP_L2SPECTYPE_DEFAULT:
284 case L2TP_L2SPECTYPE_NONE:
290 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
292 struct dst_entry *dst;
295 dst = sk_dst_get(tunnel->sock);
306 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
308 struct sock *sk = tunnel->sock;
310 return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
311 rcu_access_pointer(sk->sk_policy[1]));
314 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
320 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
321 unsigned char **ptr, unsigned char **optr)
323 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
326 int off = *ptr - *optr;
328 if (!pskb_may_pull(skb, off + opt_len))
331 if (skb->data != *optr) {
333 *ptr = skb->data + off;
340 #define l2tp_printk(ptr, type, func, fmt, ...) \
342 if (((ptr)->debug) & (type)) \
343 func(fmt, ##__VA_ARGS__); \
346 #define l2tp_warn(ptr, type, fmt, ...) \
347 l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
348 #define l2tp_info(ptr, type, fmt, ...) \
349 l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
350 #define l2tp_dbg(ptr, type, fmt, ...) \
351 l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
353 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
354 MODULE_ALIAS("net-l2tp-type-" __stringify(type))
356 #endif /* _L2TP_CORE_H_ */