Root/net/l2tp/l2tp_core.h

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/* Debug message categories for the DEBUG socket option */
27enum {
28    L2TP_MSG_DEBUG = (1 << 0), /* verbose debug (if
29                         * compiled in) */
30    L2TP_MSG_CONTROL = (1 << 1), /* userspace - kernel
31                         * interface */
32    L2TP_MSG_SEQ = (1 << 2), /* sequence numbers */
33    L2TP_MSG_DATA = (1 << 3), /* data packets */
34};
35
36struct sk_buff;
37
38struct l2tp_stats {
39    atomic_long_t tx_packets;
40    atomic_long_t tx_bytes;
41    atomic_long_t tx_errors;
42    atomic_long_t rx_packets;
43    atomic_long_t rx_bytes;
44    atomic_long_t rx_seq_discards;
45    atomic_long_t rx_oos_packets;
46    atomic_long_t rx_errors;
47    atomic_long_t rx_cookie_discards;
48};
49
50struct l2tp_tunnel;
51
52/* Describes a session. Contains information to determine incoming
53 * packets and transmit outgoing ones.
54 */
55struct l2tp_session_cfg {
56    enum l2tp_pwtype pw_type;
57    unsigned int data_seq:2; /* data sequencing level
58                         * 0 => none, 1 => IP only,
59                         * 2 => all
60                         */
61    unsigned int recv_seq:1; /* expect receive packets with
62                         * sequence numbers? */
63    unsigned int send_seq:1; /* send packets with sequence
64                         * numbers? */
65    unsigned int lns_mode:1; /* behave as LNS? LAC enables
66                         * sequence numbers under
67                         * control of LNS. */
68    int debug; /* bitmask of debug message
69                         * categories */
70    u16 vlan_id; /* VLAN pseudowire only */
71    u16 offset; /* offset to payload */
72    u16 l2specific_len; /* Layer 2 specific length */
73    u16 l2specific_type; /* Layer 2 specific type */
74    u8 cookie[8]; /* optional cookie */
75    int cookie_len; /* 0, 4 or 8 bytes */
76    u8 peer_cookie[8]; /* peer's cookie */
77    int peer_cookie_len; /* 0, 4 or 8 bytes */
78    int reorder_timeout; /* configured reorder timeout
79                          * (in jiffies) */
80    int mtu;
81    int mru;
82    char *ifname;
83};
84
85struct l2tp_session {
86    int magic; /* should be
87                         * L2TP_SESSION_MAGIC */
88
89    struct l2tp_tunnel *tunnel; /* back pointer to tunnel
90                         * context */
91    u32 session_id;
92    u32 peer_session_id;
93    u8 cookie[8];
94    int cookie_len;
95    u8 peer_cookie[8];
96    int peer_cookie_len;
97    u16 offset; /* offset from end of L2TP header
98                           to beginning of data */
99    u16 l2specific_len;
100    u16 l2specific_type;
101    u16 hdr_len;
102    u32 nr; /* session NR state (receive) */
103    u32 ns; /* session NR state (send) */
104    struct sk_buff_head reorder_q; /* receive reorder queue */
105    u32 nr_max; /* max NR. Depends on tunnel */
106    u32 nr_window_size; /* NR window size */
107    u32 nr_oos; /* NR of last OOS packet */
108    int nr_oos_count; /* For OOS recovery */
109    int nr_oos_count_max;
110    struct hlist_node hlist; /* Hash list node */
111    atomic_t ref_count;
112
113    char name[32]; /* for logging */
114    char ifname[IFNAMSIZ];
115    unsigned int data_seq:2; /* data sequencing level
116                         * 0 => none, 1 => IP only,
117                         * 2 => all
118                         */
119    unsigned int recv_seq:1; /* expect receive packets with
120                         * sequence numbers? */
121    unsigned int send_seq:1; /* send packets with sequence
122                         * numbers? */
123    unsigned int lns_mode:1; /* behave as LNS? LAC enables
124                         * sequence numbers under
125                         * control of LNS. */
126    int debug; /* bitmask of debug message
127                         * categories */
128    int reorder_timeout; /* configured reorder timeout
129                          * (in jiffies) */
130    int reorder_skip; /* set if skip to next nr */
131    int mtu;
132    int mru;
133    enum l2tp_pwtype pwtype;
134    struct l2tp_stats stats;
135    struct hlist_node global_hlist; /* Global hash list node */
136
137    int (*build_header)(struct l2tp_session *session, void *buf);
138    void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
139    void (*session_close)(struct l2tp_session *session);
140    void (*ref)(struct l2tp_session *session);
141    void (*deref)(struct l2tp_session *session);
142#if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
143    void (*show)(struct seq_file *m, void *priv);
144#endif
145    uint8_t priv[0]; /* private data */
146};
147
148/* Describes the tunnel. It contains info to track all the associated
149 * sessions so incoming packets can be sorted out
150 */
151struct l2tp_tunnel_cfg {
152    int debug; /* bitmask of debug message
153                         * categories */
154    enum l2tp_encap_type encap;
155
156    /* Used only for kernel-created sockets */
157    struct in_addr local_ip;
158    struct in_addr peer_ip;
159#if IS_ENABLED(CONFIG_IPV6)
160    struct in6_addr *local_ip6;
161    struct in6_addr *peer_ip6;
162#endif
163    u16 local_udp_port;
164    u16 peer_udp_port;
165    unsigned int use_udp_checksums:1;
166};
167
168struct l2tp_tunnel {
169    int magic; /* Should be L2TP_TUNNEL_MAGIC */
170    struct rcu_head rcu;
171    rwlock_t hlist_lock; /* protect session_hlist */
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
206struct l2tp_nl_cmd_ops {
207    int (*session_create)(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
208    int (*session_delete)(struct l2tp_session *session);
209};
210
211static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
212{
213    return &tunnel->priv[0];
214}
215
216static inline void *l2tp_session_priv(struct l2tp_session *session)
217{
218    return &session->priv[0];
219}
220
221static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
222{
223    struct l2tp_tunnel *tunnel;
224
225    if (sk == NULL)
226        return NULL;
227
228    sock_hold(sk);
229    tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
230    if (tunnel == NULL) {
231        sock_put(sk);
232        goto out;
233    }
234
235    BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
236
237out:
238    return tunnel;
239}
240
241struct l2tp_session *l2tp_session_find(struct net *net,
242                       struct l2tp_tunnel *tunnel,
243                       u32 session_id);
244struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth);
245struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname);
246struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
247struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);
248
249int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
250               u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
251               struct l2tp_tunnel **tunnelp);
252void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
253int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
254struct l2tp_session *l2tp_session_create(int priv_size,
255                     struct l2tp_tunnel *tunnel,
256                     u32 session_id, u32 peer_session_id,
257                     struct l2tp_session_cfg *cfg);
258void __l2tp_session_unhash(struct l2tp_session *session);
259int l2tp_session_delete(struct l2tp_session *session);
260void l2tp_session_free(struct l2tp_session *session);
261void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
262              unsigned char *ptr, unsigned char *optr, u16 hdrflags,
263              int length, int (*payload_hook)(struct sk_buff *skb));
264int l2tp_session_queue_purge(struct l2tp_session *session);
265int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
266void l2tp_session_set_header_len(struct l2tp_session *session, int version);
267
268int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
269          int hdr_len);
270
271int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
272             const struct l2tp_nl_cmd_ops *ops);
273void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
274
275/* Session reference counts. Incremented when code obtains a reference
276 * to a session.
277 */
278static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
279{
280    atomic_inc(&session->ref_count);
281}
282
283static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
284{
285    if (atomic_dec_and_test(&session->ref_count))
286        l2tp_session_free(session);
287}
288
289#ifdef L2TP_REFCNT_DEBUG
290#define l2tp_session_inc_refcount(_s) \
291do { \
292    pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", \
293         __func__, __LINE__, (_s)->name, \
294         atomic_read(&_s->ref_count)); \
295    l2tp_session_inc_refcount_1(_s); \
296} while (0)
297#define l2tp_session_dec_refcount(_s) \
298do { \
299    pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", \
300         __func__, __LINE__, (_s)->name, \
301         atomic_read(&_s->ref_count)); \
302    l2tp_session_dec_refcount_1(_s); \
303} while (0)
304#else
305#define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
306#define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
307#endif
308
309#define l2tp_printk(ptr, type, func, fmt, ...) \
310do { \
311    if (((ptr)->debug) & (type)) \
312        func(fmt, ##__VA_ARGS__); \
313} while (0)
314
315#define l2tp_warn(ptr, type, fmt, ...) \
316    l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
317#define l2tp_info(ptr, type, fmt, ...) \
318    l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
319#define l2tp_dbg(ptr, type, fmt, ...) \
320    l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
321
322#endif /* _L2TP_CORE_H_ */
323

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