1/* SPDX-License-Identifier: GPL-2.0-only */
2/* L2TP internal definitions.
3 *
4 * Copyright (c) 2008,2009 Katalix Systems Ltd
5 */
6#include <linux/refcount.h>
7
8#ifndef _L2TP_CORE_H_
9#define _L2TP_CORE_H_
10
11#include <net/dst.h>
12#include <net/sock.h>
13
14#ifdef CONFIG_XFRM
15#include <net/xfrm.h>
16#endif
17
18/* Random numbers used for internal consistency checks of tunnel and session structures */
19#define L2TP_SESSION_MAGIC 0x0C04EB7D
20
21struct sk_buff;
22
23struct l2tp_stats {
24 atomic_long_t tx_packets;
25 atomic_long_t tx_bytes;
26 atomic_long_t tx_errors;
27 atomic_long_t rx_packets;
28 atomic_long_t rx_bytes;
29 atomic_long_t rx_seq_discards;
30 atomic_long_t rx_oos_packets;
31 atomic_long_t rx_errors;
32 atomic_long_t rx_cookie_discards;
33 atomic_long_t rx_invalid;
34};
35
36struct l2tp_tunnel;
37
38/* L2TP session configuration */
39struct l2tp_session_cfg {
40 enum l2tp_pwtype pw_type;
41 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
42 unsigned int send_seq:1; /* send packets with sequence numbers? */
43 unsigned int lns_mode:1; /* behave as LNS?
44 * LAC enables sequence numbers under LNS control.
45 */
46 u16 l2specific_type; /* Layer 2 specific type */
47 u8 cookie[8]; /* optional cookie */
48 int cookie_len; /* 0, 4 or 8 bytes */
49 u8 peer_cookie[8]; /* peer's cookie */
50 int peer_cookie_len; /* 0, 4 or 8 bytes */
51 int reorder_timeout; /* configured reorder timeout (in jiffies) */
52 char *ifname;
53};
54
55struct l2tp_session_coll_list {
56 spinlock_t lock; /* for access to list */
57 struct list_head list;
58 refcount_t ref_count;
59};
60
61/* Represents a session (pseudowire) instance.
62 * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
63 * Is linked into a per-tunnel session list and a per-net ("global") IDR tree.
64 */
65#define L2TP_SESSION_NAME_MAX 32
66struct l2tp_session {
67 int magic; /* should be L2TP_SESSION_MAGIC */
68 long dead;
69 struct rcu_head rcu;
70
71 struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */
72 u32 session_id;
73 u32 peer_session_id;
74 u8 cookie[8];
75 int cookie_len;
76 u8 peer_cookie[8];
77 int peer_cookie_len;
78 u16 l2specific_type;
79 u16 hdr_len;
80 u32 nr; /* session NR state (receive) */
81 u32 ns; /* session NR state (send) */
82 struct sk_buff_head reorder_q; /* receive reorder queue */
83 u32 nr_max; /* max NR. Depends on tunnel */
84 u32 nr_window_size; /* NR window size */
85 u32 nr_oos; /* NR of last OOS packet */
86 int nr_oos_count; /* for OOS recovery */
87 int nr_oos_count_max;
88 struct list_head list; /* per-tunnel list node */
89 refcount_t ref_count;
90 struct hlist_node hlist; /* per-net session hlist */
91 unsigned long hlist_key; /* key for session hlist */
92 struct l2tp_session_coll_list *coll_list; /* session collision list */
93 struct list_head clist; /* for coll_list */
94
95 char name[L2TP_SESSION_NAME_MAX]; /* for logging */
96 char ifname[IFNAMSIZ];
97 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
98 unsigned int send_seq:1; /* send packets with sequence numbers? */
99 unsigned int lns_mode:1; /* behave as LNS?
100 * LAC enables sequence numbers under LNS control.
101 */
102 int reorder_timeout; /* configured reorder timeout (in jiffies) */
103 int reorder_skip; /* set if skip to next nr */
104 enum l2tp_pwtype pwtype;
105 struct l2tp_stats stats;
106 struct work_struct del_work;
107
108 /* Session receive handler for data packets.
109 * Each pseudowire implementation should implement this callback in order to
110 * handle incoming packets. Packets are passed to the pseudowire handler after
111 * reordering, if data sequence numbers are enabled for the session.
112 */
113 void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
114
115 /* Session close handler.
116 * Each pseudowire implementation may implement this callback in order to carry
117 * out pseudowire-specific shutdown actions.
118 * The callback is called by core after unlisting the session and purging its
119 * reorder queue.
120 */
121 void (*session_close)(struct l2tp_session *session);
122
123 /* Session show handler.
124 * Pseudowire-specific implementation of debugfs session rendering.
125 * The callback is called by l2tp_debugfs.c after rendering core session
126 * information.
127 */
128 void (*show)(struct seq_file *m, void *priv);
129
130 u8 priv[]; /* private data */
131};
132
133/* L2TP tunnel configuration */
134struct l2tp_tunnel_cfg {
135 enum l2tp_encap_type encap;
136
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;
143#endif
144 u16 local_udp_port;
145 u16 peer_udp_port;
146 unsigned int use_udp_checksums:1,
147 udp6_zero_tx_checksums:1,
148 udp6_zero_rx_checksums:1;
149};
150
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 list of sessions belonging to the tunnel instance.
155 * Is linked into a per-net list of tunnels.
156 */
157#define L2TP_TUNNEL_NAME_MAX 20
158struct l2tp_tunnel {
159 unsigned long dead;
160
161 struct rcu_head rcu;
162 spinlock_t list_lock; /* write-protection for session_list */
163 bool acpt_newsess; /* indicates whether this tunnel accepts
164 * new sessions. Protected by list_lock.
165 */
166 struct list_head session_list; /* list of sessions */
167 u32 tunnel_id;
168 u32 peer_tunnel_id;
169 int version; /* 2=>L2TPv2, 3=>L2TPv3 */
170
171 char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */
172 enum l2tp_encap_type encap;
173 struct l2tp_stats stats;
174
175 struct net *l2tp_net; /* the net we belong to */
176
177 refcount_t ref_count;
178 struct sock *sock; /* parent socket */
179 int fd; /* parent fd, if tunnel socket was created
180 * by userspace
181 */
182
183 struct work_struct del_work;
184};
185
186/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
187struct l2tp_nl_cmd_ops {
188 /* The pseudowire session create callback is responsible for creating a session
189 * instance for a specific pseudowire type.
190 * It must call l2tp_session_create and l2tp_session_register to register the
191 * session instance, as well as carry out any pseudowire-specific initialisation.
192 * It must return >= 0 on success, or an appropriate negative errno value on failure.
193 */
194 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
195 u32 session_id, u32 peer_session_id,
196 struct l2tp_session_cfg *cfg);
197
198 /* The pseudowire session delete callback is responsible for initiating the deletion
199 * of a session instance.
200 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific
201 * teardown actions.
202 */
203 void (*session_delete)(struct l2tp_session *session);
204};
205
206static inline void *l2tp_session_priv(struct l2tp_session *session)
207{
208 return &session->priv[0];
209}
210
211/* Tunnel and session refcounts */
212void l2tp_tunnel_put(struct l2tp_tunnel *tunnel);
213void l2tp_session_put(struct l2tp_session *session);
214
215/* Tunnel and session lookup.
216 * These functions take a reference on the instances they return, so
217 * the caller must ensure that the reference is dropped appropriately.
218 */
219struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
220struct l2tp_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key);
221
222struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
223struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
224struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
225 u32 tunnel_id, u32 session_id);
226struct l2tp_session *l2tp_session_get_next(const struct net *net, struct sock *sk, int pver,
227 u32 tunnel_id, unsigned long *key);
228struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
229 const char *ifname);
230
231/* Tunnel and session lifetime management.
232 * Creation of a new instance is a two-step process: create, then register.
233 * Destruction is triggered using the *_delete functions, and completes asynchronously.
234 */
235int l2tp_tunnel_create(int fd, int version, u32 tunnel_id,
236 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
237 struct l2tp_tunnel **tunnelp);
238int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
239 struct l2tp_tunnel_cfg *cfg);
240void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
241
242struct l2tp_session *l2tp_session_create(int priv_size,
243 struct l2tp_tunnel *tunnel,
244 u32 session_id, u32 peer_session_id,
245 struct l2tp_session_cfg *cfg);
246int l2tp_session_register(struct l2tp_session *session,
247 struct l2tp_tunnel *tunnel);
248void l2tp_session_delete(struct l2tp_session *session);
249
250/* Receive path helpers. If data sequencing is enabled for the session these
251 * functions handle queuing and reordering prior to passing packets to the
252 * pseudowire code to be passed to userspace.
253 */
254void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
255 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
256 int length);
257int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
258
259/* Transmit path helpers for sending packets over the tunnel socket. */
260void l2tp_session_set_header_len(struct l2tp_session *session, int version,
261 enum l2tp_encap_type encap);
262int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb);
263
264/* Pseudowire management.
265 * Pseudowires should register with l2tp core on module init, and unregister
266 * on module exit.
267 */
268int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
269void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
270
271/* IOCTL helper for IP encap modules. */
272int l2tp_ioctl(struct sock *sk, int cmd, int *karg);
273
274struct l2tp_tunnel *l2tp_sk_to_tunnel(const struct sock *sk);
275
276static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
277{
278 switch (session->l2specific_type) {
279 case L2TP_L2SPECTYPE_DEFAULT:
280 return 4;
281 case L2TP_L2SPECTYPE_NONE:
282 default:
283 return 0;
284 }
285}
286
287static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
288{
289 struct dst_entry *dst;
290 u32 mtu;
291
292 dst = sk_dst_get(sk: tunnel->sock);
293 if (!dst)
294 return 0;
295
296 mtu = dst_mtu(dst);
297 dst_release(dst);
298
299 return mtu;
300}
301
302#ifdef CONFIG_XFRM
303static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
304{
305 struct sock *sk = tunnel->sock;
306
307 return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
308 rcu_access_pointer(sk->sk_policy[1]));
309}
310#else
311static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
312{
313 return false;
314}
315#endif
316
317static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
318 unsigned char **ptr, unsigned char **optr)
319{
320 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
321
322 if (opt_len > 0) {
323 int off = *ptr - *optr;
324
325 if (!pskb_may_pull(skb, len: off + opt_len))
326 return -1;
327
328 if (skb->data != *optr) {
329 *optr = skb->data;
330 *ptr = skb->data + off;
331 }
332 }
333
334 return 0;
335}
336
337#define MODULE_ALIAS_L2TP_PWTYPE(type) \
338 MODULE_ALIAS("net-l2tp-type-" __stringify(type))
339
340#endif /* _L2TP_CORE_H_ */
341

source code of linux/net/l2tp/l2tp_core.h