1 /*
2 * L2TP internal definitions.
3 *
4 * Copyright (c) 2008,2009 Katalix Systems Ltd
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11 #ifndef _L2TP_CORE_H_
12 #define _L2TP_CORE_H_
13
14 /* Just some random numbers */
15 #define L2TP_TUNNEL_MAGIC 0x42114DDA
16 #define L2TP_SESSION_MAGIC 0x0C04EB7D
17
18 /* Per tunnel, session hash table size */
19 #define L2TP_HASH_BITS 4
20 #define L2TP_HASH_SIZE (1 << L2TP_HASH_BITS)
21
22 /* System-wide, session hash table size */
23 #define L2TP_HASH_BITS_2 8
24 #define L2TP_HASH_SIZE_2 (1 << L2TP_HASH_BITS_2)
25
26 struct sk_buff;
27
28 struct l2tp_stats {
29 atomic_long_t tx_packets;
30 atomic_long_t tx_bytes;
31 atomic_long_t tx_errors;
32 atomic_long_t rx_packets;
33 atomic_long_t rx_bytes;
34 atomic_long_t rx_seq_discards;
35 atomic_long_t rx_oos_packets;
36 atomic_long_t rx_errors;
37 atomic_long_t rx_cookie_discards;
38 };
39
40 struct l2tp_tunnel;
41
42 /* Describes a session. Contains information to determine incoming
43 * packets and transmit outgoing ones.
44 */
45 struct l2tp_session_cfg {
46 enum l2tp_pwtype pw_type;
47 unsigned int data_seq:2; /* data sequencing level
48 * 0 => none, 1 => IP only,
49 * 2 => all
50 */
51 unsigned int recv_seq:1; /* expect receive packets with
52 * sequence numbers? */
53 unsigned int send_seq:1; /* send packets with sequence
54 * numbers? */
55 unsigned int lns_mode:1; /* behave as LNS? LAC enables
56 * sequence numbers under
57 * control of LNS. */
58 int debug; /* bitmask of debug message
59 * categories */
60 u16 vlan_id; /* VLAN pseudowire only */
61 u16 offset; /* offset to payload */
62 u16 l2specific_len; /* Layer 2 specific length */
63 u16 l2specific_type; /* Layer 2 specific type */
64 u8 cookie[8]; /* optional cookie */
65 int cookie_len; /* 0, 4 or 8 bytes */
66 u8 peer_cookie[8]; /* peer's cookie */
67 int peer_cookie_len; /* 0, 4 or 8 bytes */
68 int reorder_timeout; /* configured reorder timeout
69 * (in jiffies) */
70 int mtu;
71 int mru;
72 char *ifname;
73 };
74
75 struct l2tp_session {
76 int magic; /* should be
77 * L2TP_SESSION_MAGIC */
78 long dead;
79
80 struct l2tp_tunnel *tunnel; /* back pointer to tunnel
81 * context */
82 u32 session_id;
83 u32 peer_session_id;
84 u8 cookie[8];
85 int cookie_len;
86 u8 peer_cookie[8];
87 int peer_cookie_len;
88 u16 offset; /* offset from end of L2TP header
89 to beginning of data */
90 u16 l2specific_len;
91 u16 l2specific_type;
92 u16 hdr_len;
93 u32 nr; /* session NR state (receive) */
94 u32 ns; /* session NR state (send) */
95 struct sk_buff_head reorder_q; /* receive reorder queue */
96 u32 nr_max; /* max NR. Depends on tunnel */
97 u32 nr_window_size; /* NR window size */
98 u32 nr_oos; /* NR of last OOS packet */
99 int nr_oos_count; /* For OOS recovery */
100 int nr_oos_count_max;
101 struct hlist_node hlist; /* Hash list node */
102 atomic_t ref_count;
103
104 char name[32]; /* for logging */
105 char ifname[IFNAMSIZ];
106 unsigned int data_seq:2; /* data sequencing level
107 * 0 => none, 1 => IP only,
108 * 2 => all
109 */
110 unsigned int recv_seq:1; /* expect receive packets with
111 * sequence numbers? */
112 unsigned int send_seq:1; /* send packets with sequence
113 * numbers? */
114 unsigned int lns_mode:1; /* behave as LNS? LAC enables
115 * sequence numbers under
116 * control of LNS. */
117 int debug; /* bitmask of debug message
118 * categories */
119 int reorder_timeout; /* configured reorder timeout
120 * (in jiffies) */
121 int reorder_skip; /* set if skip to next nr */
122 int mtu;
123 int mru;
124 enum l2tp_pwtype pwtype;
125 struct l2tp_stats stats;
126 struct hlist_node global_hlist; /* Global hash list node */
127
128 int (*build_header)(struct l2tp_session *session, void *buf);
129 void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
130 void (*session_close)(struct l2tp_session *session);
131 void (*ref)(struct l2tp_session *session);
132 void (*deref)(struct l2tp_session *session);
133 #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
134 void (*show)(struct seq_file *m, void *priv);
135 #endif
136 uint8_t priv[0]; /* private data */
137 };
138
139 /* Describes the tunnel. It contains info to track all the associated
140 * sessions so incoming packets can be sorted out
141 */
142 struct l2tp_tunnel_cfg {
143 int debug; /* bitmask of debug message
144 * categories */
145 enum l2tp_encap_type encap;
146
147 /* Used only for kernel-created sockets */
148 struct in_addr local_ip;
149 struct in_addr peer_ip;
150 #if IS_ENABLED(CONFIG_IPV6)
151 struct in6_addr *local_ip6;
152 struct in6_addr *peer_ip6;
153 #endif
154 u16 local_udp_port;
155 u16 peer_udp_port;
156 unsigned int use_udp_checksums:1,
157 udp6_zero_tx_checksums:1,
158 udp6_zero_rx_checksums:1;
159 };
160
161 struct l2tp_tunnel {
162 int magic; /* Should be L2TP_TUNNEL_MAGIC */
163
164 unsigned long dead;
165
166 struct rcu_head rcu;
167 rwlock_t hlist_lock; /* protect session_hlist */
168 bool acpt_newsess; /* Indicates whether this
169 * tunnel accepts new sessions.
170 * Protected by hlist_lock.
171 */
172 struct hlist_head session_hlist[L2TP_HASH_SIZE];
173 /* hashed list of sessions,
174 * hashed by id */
175 u32 tunnel_id;
176 u32 peer_tunnel_id;
177 int version; /* 2=>L2TPv2, 3=>L2TPv3 */
178
179 char name[20]; /* for logging */
180 int debug; /* bitmask of debug message
181 * categories */
182 enum l2tp_encap_type encap;
183 struct l2tp_stats stats;
184
185 struct list_head list; /* Keep a list of all tunnels */
186 struct net *l2tp_net; /* the net we belong to */
187
188 atomic_t ref_count;
189 #ifdef CONFIG_DEBUG_FS
190 void (*show)(struct seq_file *m, void *arg);
191 #endif
192 int (*recv_payload_hook)(struct sk_buff *skb);
193 void (*old_sk_destruct)(struct sock *);
194 struct sock *sock; /* Parent socket */
195 int fd; /* Parent fd, if tunnel socket
196 * was created by userspace */
197 #if IS_ENABLED(CONFIG_IPV6)
198 bool v4mapped;
199 #endif
200
201 struct work_struct del_work;
202
203 uint8_t priv[0]; /* private data */
204 };
205
206 struct l2tp_nl_cmd_ops {
207 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
208 u32 session_id, u32 peer_session_id,
209 struct l2tp_session_cfg *cfg);
210 int (*session_delete)(struct l2tp_session *session);
211 };
212
l2tp_tunnel_priv(struct l2tp_tunnel * tunnel)213 static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
214 {
215 return &tunnel->priv[0];
216 }
217
l2tp_session_priv(struct l2tp_session * session)218 static inline void *l2tp_session_priv(struct l2tp_session *session)
219 {
220 return &session->priv[0];
221 }
222
l2tp_sock_to_tunnel(struct sock * sk)223 static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
224 {
225 struct l2tp_tunnel *tunnel;
226
227 if (sk == NULL)
228 return NULL;
229
230 sock_hold(sk);
231 tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
232 if (tunnel == NULL) {
233 sock_put(sk);
234 goto out;
235 }
236
237 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
238
239 out:
240 return tunnel;
241 }
242
243 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
244
245 struct l2tp_session *l2tp_session_get(const struct net *net,
246 struct l2tp_tunnel *tunnel,
247 u32 session_id, bool do_ref);
248 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
249 bool do_ref);
250 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
251 const char *ifname,
252 bool do_ref);
253 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
254 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
255
256 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
257 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
258 struct l2tp_tunnel **tunnelp);
259 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
260 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
261 struct l2tp_session *l2tp_session_create(int priv_size,
262 struct l2tp_tunnel *tunnel,
263 u32 session_id, u32 peer_session_id,
264 struct l2tp_session_cfg *cfg);
265 int l2tp_session_register(struct l2tp_session *session,
266 struct l2tp_tunnel *tunnel);
267
268 void __l2tp_session_unhash(struct l2tp_session *session);
269 int l2tp_session_delete(struct l2tp_session *session);
270 void l2tp_session_free(struct l2tp_session *session);
271 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
272 unsigned char *ptr, unsigned char *optr, u16 hdrflags,
273 int length, int (*payload_hook)(struct sk_buff *skb));
274 int l2tp_session_queue_purge(struct l2tp_session *session);
275 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
276 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
277
278 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
279 int hdr_len);
280
281 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
282 const struct l2tp_nl_cmd_ops *ops);
283 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
284 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
285
l2tp_tunnel_inc_refcount(struct l2tp_tunnel * tunnel)286 static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
287 {
288 atomic_inc(&tunnel->ref_count);
289 }
290
l2tp_tunnel_dec_refcount(struct l2tp_tunnel * tunnel)291 static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
292 {
293 if (atomic_dec_and_test(&tunnel->ref_count))
294 kfree_rcu(tunnel, rcu);
295 }
296
297 /* Session reference counts. Incremented when code obtains a reference
298 * to a session.
299 */
l2tp_session_inc_refcount_1(struct l2tp_session * session)300 static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
301 {
302 atomic_inc(&session->ref_count);
303 }
304
l2tp_session_dec_refcount_1(struct l2tp_session * session)305 static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
306 {
307 if (atomic_dec_and_test(&session->ref_count))
308 l2tp_session_free(session);
309 }
310
311 #ifdef L2TP_REFCNT_DEBUG
312 #define l2tp_session_inc_refcount(_s) \
313 do { \
314 pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", \
315 __func__, __LINE__, (_s)->name, \
316 atomic_read(&_s->ref_count)); \
317 l2tp_session_inc_refcount_1(_s); \
318 } while (0)
319 #define l2tp_session_dec_refcount(_s) \
320 do { \
321 pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", \
322 __func__, __LINE__, (_s)->name, \
323 atomic_read(&_s->ref_count)); \
324 l2tp_session_dec_refcount_1(_s); \
325 } while (0)
326 #else
327 #define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
328 #define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
329 #endif
330
l2tp_get_l2specific_len(struct l2tp_session * session)331 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
332 {
333 switch (session->l2specific_type) {
334 case L2TP_L2SPECTYPE_DEFAULT:
335 return 4;
336 case L2TP_L2SPECTYPE_NONE:
337 default:
338 return 0;
339 }
340 }
341
l2tp_v3_ensure_opt_in_linear(struct l2tp_session * session,struct sk_buff * skb,unsigned char ** ptr,unsigned char ** optr)342 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
343 unsigned char **ptr, unsigned char **optr)
344 {
345 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
346
347 if (opt_len > 0) {
348 int off = *ptr - *optr;
349
350 if (!pskb_may_pull(skb, off + opt_len))
351 return -1;
352
353 if (skb->data != *optr) {
354 *optr = skb->data;
355 *ptr = skb->data + off;
356 }
357 }
358
359 return 0;
360 }
361
362 #define l2tp_printk(ptr, type, func, fmt, ...) \
363 do { \
364 if (((ptr)->debug) & (type)) \
365 func(fmt, ##__VA_ARGS__); \
366 } while (0)
367
368 #define l2tp_warn(ptr, type, fmt, ...) \
369 l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
370 #define l2tp_info(ptr, type, fmt, ...) \
371 l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
372 #define l2tp_dbg(ptr, type, fmt, ...) \
373 l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
374
375 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
376 MODULE_ALIAS("net-l2tp-type-" __stringify(type))
377
378 #endif /* _L2TP_CORE_H_ */
379