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_TUNNEL_MAGIC 0x42114DDA |
20 | #define L2TP_SESSION_MAGIC 0x0C04EB7D |
21 | |
22 | /* Per tunnel session hash table size */ |
23 | #define L2TP_HASH_BITS 4 |
24 | #define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS) |
25 | |
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) |
29 | |
30 | struct sk_buff; |
31 | |
32 | struct l2tp_stats { |
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; |
42 | atomic_long_t rx_invalid; |
43 | }; |
44 | |
45 | struct l2tp_tunnel; |
46 | |
47 | /* L2TP session configuration */ |
48 | struct l2tp_session_cfg { |
49 | enum l2tp_pwtype pw_type; |
50 | unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ |
51 | unsigned int send_seq:1; /* send packets with sequence numbers? */ |
52 | unsigned int lns_mode:1; /* behave as LNS? |
53 | * LAC enables sequence numbers under LNS control. |
54 | */ |
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) */ |
61 | char *ifname; |
62 | }; |
63 | |
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. |
68 | */ |
69 | #define L2TP_SESSION_NAME_MAX 32 |
70 | struct l2tp_session { |
71 | int magic; /* should be L2TP_SESSION_MAGIC */ |
72 | long dead; |
73 | |
74 | struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */ |
75 | u32 session_id; |
76 | u32 peer_session_id; |
77 | u8 cookie[8]; |
78 | int cookie_len; |
79 | u8 peer_cookie[8]; |
80 | int peer_cookie_len; |
81 | u16 l2specific_type; |
82 | u16 hdr_len; |
83 | u32 nr; /* session NR state (receive) */ |
84 | u32 ns; /* session NR state (send) */ |
85 | struct sk_buff_head reorder_q; /* receive reorder queue */ |
86 | u32 nr_max; /* max NR. Depends on tunnel */ |
87 | u32 nr_window_size; /* NR window size */ |
88 | u32 nr_oos; /* NR of last OOS packet */ |
89 | int nr_oos_count; /* for OOS recovery */ |
90 | int nr_oos_count_max; |
91 | struct hlist_node hlist; /* hash list node */ |
92 | refcount_t ref_count; |
93 | |
94 | char name[L2TP_SESSION_NAME_MAX]; /* for logging */ |
95 | char ifname[IFNAMSIZ]; |
96 | unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ |
97 | unsigned int send_seq:1; /* send packets with sequence numbers? */ |
98 | unsigned int lns_mode:1; /* behave as LNS? |
99 | * LAC enables sequence numbers under LNS control. |
100 | */ |
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 */ |
106 | |
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. |
111 | */ |
112 | void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len); |
113 | |
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 |
118 | * reorder queue. |
119 | */ |
120 | void (*session_close)(struct l2tp_session *session); |
121 | |
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 |
125 | * information. |
126 | */ |
127 | void (*show)(struct seq_file *m, void *priv); |
128 | |
129 | u8 priv[]; /* private data */ |
130 | }; |
131 | |
132 | /* L2TP tunnel configuration */ |
133 | struct l2tp_tunnel_cfg { |
134 | enum l2tp_encap_type encap; |
135 | |
136 | /* Used only for kernel-created sockets */ |
137 | struct in_addr local_ip; |
138 | struct in_addr peer_ip; |
139 | #if IS_ENABLED(CONFIG_IPV6) |
140 | struct in6_addr *local_ip6; |
141 | struct in6_addr *peer_ip6; |
142 | #endif |
143 | u16 local_udp_port; |
144 | u16 peer_udp_port; |
145 | unsigned int use_udp_checksums:1, |
146 | udp6_zero_tx_checksums:1, |
147 | udp6_zero_rx_checksums:1; |
148 | }; |
149 | |
150 | /* Represents a tunnel instance. |
151 | * Tracks runtime state including IO statistics. |
152 | * Holds the tunnel socket (either passed from userspace or directly created by the kernel). |
153 | * Maintains a hashlist of sessions belonging to the tunnel instance. |
154 | * Is linked into a per-net list of tunnels. |
155 | */ |
156 | #define L2TP_TUNNEL_NAME_MAX 20 |
157 | struct l2tp_tunnel { |
158 | int magic; /* Should be L2TP_TUNNEL_MAGIC */ |
159 | |
160 | unsigned long dead; |
161 | |
162 | struct rcu_head rcu; |
163 | spinlock_t hlist_lock; /* write-protection for session_hlist */ |
164 | bool acpt_newsess; /* indicates whether this tunnel accepts |
165 | * new sessions. Protected by hlist_lock. |
166 | */ |
167 | struct hlist_head session_hlist[L2TP_HASH_SIZE]; |
168 | /* hashed list of sessions, hashed by id */ |
169 | u32 tunnel_id; |
170 | u32 peer_tunnel_id; |
171 | int version; /* 2=>L2TPv2, 3=>L2TPv3 */ |
172 | |
173 | char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */ |
174 | enum l2tp_encap_type encap; |
175 | struct l2tp_stats stats; |
176 | |
177 | struct list_head list; /* list node on per-namespace list of tunnels */ |
178 | struct net *l2tp_net; /* the net we belong to */ |
179 | |
180 | refcount_t ref_count; |
181 | void (*old_sk_destruct)(struct sock *sk); |
182 | struct sock *sock; /* parent socket */ |
183 | int fd; /* parent fd, if tunnel socket was created |
184 | * by userspace |
185 | */ |
186 | |
187 | struct work_struct del_work; |
188 | }; |
189 | |
190 | /* Pseudowire ops callbacks for use with the l2tp genetlink interface */ |
191 | struct l2tp_nl_cmd_ops { |
192 | /* The pseudowire session create callback is responsible for creating a session |
193 | * instance for a specific pseudowire type. |
194 | * It must call l2tp_session_create and l2tp_session_register to register the |
195 | * session instance, as well as carry out any pseudowire-specific initialisation. |
196 | * It must return >= 0 on success, or an appropriate negative errno value on failure. |
197 | */ |
198 | int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel, |
199 | u32 session_id, u32 peer_session_id, |
200 | struct l2tp_session_cfg *cfg); |
201 | |
202 | /* The pseudowire session delete callback is responsible for initiating the deletion |
203 | * of a session instance. |
204 | * It must call l2tp_session_delete, as well as carry out any pseudowire-specific |
205 | * teardown actions. |
206 | */ |
207 | void (*session_delete)(struct l2tp_session *session); |
208 | }; |
209 | |
210 | static inline void *l2tp_session_priv(struct l2tp_session *session) |
211 | { |
212 | return &session->priv[0]; |
213 | } |
214 | |
215 | /* Tunnel and session refcounts */ |
216 | void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel); |
217 | void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel); |
218 | void l2tp_session_inc_refcount(struct l2tp_session *session); |
219 | void l2tp_session_dec_refcount(struct l2tp_session *session); |
220 | |
221 | /* Tunnel and session lookup. |
222 | * These functions take a reference on the instances they return, so |
223 | * the caller must ensure that the reference is dropped appropriately. |
224 | */ |
225 | struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id); |
226 | struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth); |
227 | struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, |
228 | u32 session_id); |
229 | |
230 | struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id); |
231 | struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth); |
232 | struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, |
233 | const char *ifname); |
234 | |
235 | /* Tunnel and session lifetime management. |
236 | * Creation of a new instance is a two-step process: create, then register. |
237 | * Destruction is triggered using the *_delete functions, and completes asynchronously. |
238 | */ |
239 | int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, |
240 | u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, |
241 | struct l2tp_tunnel **tunnelp); |
242 | int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, |
243 | struct l2tp_tunnel_cfg *cfg); |
244 | void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel); |
245 | |
246 | struct l2tp_session *l2tp_session_create(int priv_size, |
247 | struct l2tp_tunnel *tunnel, |
248 | u32 session_id, u32 peer_session_id, |
249 | struct l2tp_session_cfg *cfg); |
250 | int l2tp_session_register(struct l2tp_session *session, |
251 | struct l2tp_tunnel *tunnel); |
252 | void l2tp_session_delete(struct l2tp_session *session); |
253 | |
254 | /* Receive path helpers. If data sequencing is enabled for the session these |
255 | * functions handle queuing and reordering prior to passing packets to the |
256 | * pseudowire code to be passed to userspace. |
257 | */ |
258 | void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, |
259 | unsigned char *ptr, unsigned char *optr, u16 hdrflags, |
260 | int length); |
261 | int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb); |
262 | |
263 | /* Transmit path helpers for sending packets over the tunnel socket. */ |
264 | void (struct l2tp_session *session, int version); |
265 | int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb); |
266 | |
267 | /* Pseudowire management. |
268 | * Pseudowires should register with l2tp core on module init, and unregister |
269 | * on module exit. |
270 | */ |
271 | int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops); |
272 | void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type); |
273 | |
274 | /* IOCTL helper for IP encap modules. */ |
275 | int l2tp_ioctl(struct sock *sk, int cmd, int *karg); |
276 | |
277 | /* Extract the tunnel structure from a socket's sk_user_data pointer, |
278 | * validating the tunnel magic feather. |
279 | */ |
280 | struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk); |
281 | |
282 | static inline int l2tp_get_l2specific_len(struct l2tp_session *session) |
283 | { |
284 | switch (session->l2specific_type) { |
285 | case L2TP_L2SPECTYPE_DEFAULT: |
286 | return 4; |
287 | case L2TP_L2SPECTYPE_NONE: |
288 | default: |
289 | return 0; |
290 | } |
291 | } |
292 | |
293 | static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel) |
294 | { |
295 | struct dst_entry *dst; |
296 | u32 mtu; |
297 | |
298 | dst = sk_dst_get(sk: tunnel->sock); |
299 | if (!dst) |
300 | return 0; |
301 | |
302 | mtu = dst_mtu(dst); |
303 | dst_release(dst); |
304 | |
305 | return mtu; |
306 | } |
307 | |
308 | #ifdef CONFIG_XFRM |
309 | static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) |
310 | { |
311 | struct sock *sk = tunnel->sock; |
312 | |
313 | return sk && (rcu_access_pointer(sk->sk_policy[0]) || |
314 | rcu_access_pointer(sk->sk_policy[1])); |
315 | } |
316 | #else |
317 | static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) |
318 | { |
319 | return false; |
320 | } |
321 | #endif |
322 | |
323 | static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb, |
324 | unsigned char **ptr, unsigned char **optr) |
325 | { |
326 | int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session); |
327 | |
328 | if (opt_len > 0) { |
329 | int off = *ptr - *optr; |
330 | |
331 | if (!pskb_may_pull(skb, len: off + opt_len)) |
332 | return -1; |
333 | |
334 | if (skb->data != *optr) { |
335 | *optr = skb->data; |
336 | *ptr = skb->data + off; |
337 | } |
338 | } |
339 | |
340 | return 0; |
341 | } |
342 | |
343 | #define MODULE_ALIAS_L2TP_PWTYPE(type) \ |
344 | MODULE_ALIAS("net-l2tp-type-" __stringify(type)) |
345 | |
346 | #endif /* _L2TP_CORE_H_ */ |
347 | |