summaryrefslogtreecommitdiff
path: root/net/l2tp/l2tp_core.h
blob: 835c4645a0ecdb80689539719bb4efce814a6661 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
/* 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;
};

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.
						 */
	int			debug;		/* bitmask of debug message categories */
	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			debug;		/* bitmask of debug message categories */
	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 {
	int			debug;		/* bitmask of debug message categories */
	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;
	rwlock_t		hlist_lock;	/* protect 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 */
	int			debug;		/* bitmask of debug message categories */
	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(struct net *net, 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,
		  int hdr_len);

/* 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);

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 l2tp_printk(ptr, type, func, fmt, ...)				\
do {									\
	if (((ptr)->debug) & (type))					\
		func(fmt, ##__VA_ARGS__);				\
} while (0)

#define l2tp_warn(ptr, type, fmt, ...)					\
	l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
#define l2tp_info(ptr, type, fmt, ...)					\
	l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
#define l2tp_dbg(ptr, type, fmt, ...)					\
	l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)

#define MODULE_ALIAS_L2TP_PWTYPE(type) \
	MODULE_ALIAS("net-l2tp-type-" __stringify(type))

#endif /* _L2TP_CORE_H_ */