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2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/net/l2tp/l2tp_core.h
....@@ -1,11 +1,7 @@
1
-/*
2
- * L2TP internal definitions.
1
+/* SPDX-License-Identifier: GPL-2.0-only */
2
+/* L2TP internal definitions.
33  *
44  * 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.
95  */
106 #include <linux/refcount.h>
117 
....@@ -19,17 +15,17 @@
1915 #include <net/xfrm.h>
2016 #endif
2117 
22
-/* Just some random numbers */
18
+/* Random numbers used for internal consistency checks of tunnel and session structures */
2319 #define L2TP_TUNNEL_MAGIC	0x42114DDA
2420 #define L2TP_SESSION_MAGIC	0x0C04EB7D
2521 
26
-/* Per tunnel, session hash table size */
22
+/* Per tunnel session hash table size */
2723 #define L2TP_HASH_BITS	4
28
-#define L2TP_HASH_SIZE	(1 << L2TP_HASH_BITS)
24
+#define L2TP_HASH_SIZE	BIT(L2TP_HASH_BITS)
2925 
30
-/* System-wide, session hash table size */
26
+/* System-wide session hash table size */
3127 #define L2TP_HASH_BITS_2	8
32
-#define L2TP_HASH_SIZE_2	(1 << L2TP_HASH_BITS_2)
28
+#define L2TP_HASH_SIZE_2	BIT(L2TP_HASH_BITS_2)
3329 
3430 struct sk_buff;
3531 
....@@ -43,41 +39,39 @@
4339 	atomic_long_t		rx_oos_packets;
4440 	atomic_long_t		rx_errors;
4541 	atomic_long_t		rx_cookie_discards;
42
+	atomic_long_t		rx_invalid;
4643 };
4744 
4845 struct l2tp_tunnel;
4946 
50
-/* Describes a session. Contains information to determine incoming
51
- * packets and transmit outgoing ones.
52
- */
47
+/* L2TP session configuration */
5348 struct l2tp_session_cfg {
5449 	enum l2tp_pwtype	pw_type;
55
-	unsigned int		recv_seq:1;	/* expect receive packets with
56
-						 * sequence numbers? */
57
-	unsigned int		send_seq:1;	/* send packets with sequence
58
-						 * numbers? */
59
-	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
60
-						 * sequence numbers under
61
-						 * control of LNS. */
62
-	int			debug;		/* bitmask of debug message
63
-						 * categories */
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
+						 */
6455 	u16			l2specific_type; /* Layer 2 specific type */
6556 	u8			cookie[8];	/* optional cookie */
6657 	int			cookie_len;	/* 0, 4 or 8 bytes */
6758 	u8			peer_cookie[8];	/* peer's cookie */
6859 	int			peer_cookie_len; /* 0, 4 or 8 bytes */
69
-	int			reorder_timeout; /* configured reorder timeout
70
-						  * (in jiffies) */
60
+	int			reorder_timeout; /* configured reorder timeout (in jiffies) */
7161 	char			*ifname;
7262 };
7363 
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
7470 struct l2tp_session {
75
-	int			magic;		/* should be
76
-						 * L2TP_SESSION_MAGIC */
71
+	int			magic;		/* should be L2TP_SESSION_MAGIC */
7772 	long			dead;
7873 
79
-	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel
80
-						 * context */
74
+	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel context */
8175 	u32			session_id;
8276 	u32			peer_session_id;
8377 	u8			cookie[8];
....@@ -92,42 +86,51 @@
9286 	u32			nr_max;		/* max NR. Depends on tunnel */
9387 	u32			nr_window_size;	/* NR window size */
9488 	u32			nr_oos;		/* NR of last OOS packet */
95
-	int			nr_oos_count;	/* For OOS recovery */
89
+	int			nr_oos_count;	/* for OOS recovery */
9690 	int			nr_oos_count_max;
97
-	struct hlist_node	hlist;		/* Hash list node */
91
+	struct hlist_node	hlist;		/* hash list node */
9892 	refcount_t		ref_count;
9993 
100
-	char			name[32];	/* for logging */
94
+	char			name[L2TP_SESSION_NAME_MAX]; /* for logging */
10195 	char			ifname[IFNAMSIZ];
102
-	unsigned int		recv_seq:1;	/* expect receive packets with
103
-						 * sequence numbers? */
104
-	unsigned int		send_seq:1;	/* send packets with sequence
105
-						 * numbers? */
106
-	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
107
-						 * sequence numbers under
108
-						 * control of LNS. */
109
-	int			debug;		/* bitmask of debug message
110
-						 * categories */
111
-	int			reorder_timeout; /* configured reorder timeout
112
-						  * (in jiffies) */
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) */
113102 	int			reorder_skip;	/* set if skip to next nr */
114103 	enum l2tp_pwtype	pwtype;
115104 	struct l2tp_stats	stats;
116
-	struct hlist_node	global_hlist;	/* Global hash list node */
105
+	struct hlist_node	global_hlist;	/* global hash list node */
117106 
118
-	int (*build_header)(struct l2tp_session *session, void *buf);
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
+	 */
119112 	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
+	 */
120120 	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
+	 */
121127 	void (*show)(struct seq_file *m, void *priv);
122
-	uint8_t			priv[0];	/* private data */
128
+
129
+	u8			priv[];		/* private data */
123130 };
124131 
125
-/* Describes the tunnel. It contains info to track all the associated
126
- * sessions so incoming packets can be sorted out
127
- */
132
+/* L2TP tunnel configuration */
128133 struct l2tp_tunnel_cfg {
129
-	int			debug;		/* bitmask of debug message
130
-						 * categories */
131134 	enum l2tp_encap_type	encap;
132135 
133136 	/* Used only for kernel-created sockets */
....@@ -144,6 +147,13 @@
144147 				udp6_zero_rx_checksums:1;
145148 };
146149 
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
147157 struct l2tp_tunnel {
148158 	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
149159 
....@@ -151,40 +161,50 @@
151161 
152162 	struct rcu_head rcu;
153163 	rwlock_t		hlist_lock;	/* protect session_hlist */
154
-	bool			acpt_newsess;	/* Indicates whether this
155
-						 * tunnel accepts new sessions.
156
-						 * Protected by hlist_lock.
164
+	bool			acpt_newsess;	/* indicates whether this tunnel accepts
165
+						 * new sessions. Protected by hlist_lock.
157166 						 */
158167 	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
159
-						/* hashed list of sessions,
160
-						 * hashed by id */
168
+						/* hashed list of sessions, hashed by id */
161169 	u32			tunnel_id;
162170 	u32			peer_tunnel_id;
163171 	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
164172 
165
-	char			name[20];	/* for logging */
166
-	int			debug;		/* bitmask of debug message
167
-						 * categories */
173
+	char			name[L2TP_TUNNEL_NAME_MAX]; /* for logging */
168174 	enum l2tp_encap_type	encap;
169175 	struct l2tp_stats	stats;
170176 
171
-	struct list_head	list;		/* Keep a list of all tunnels */
177
+	struct list_head	list;		/* list node on per-namespace list of tunnels */
172178 	struct net		*l2tp_net;	/* the net we belong to */
173179 
174180 	refcount_t		ref_count;
175
-	void (*old_sk_destruct)(struct sock *);
176
-	struct sock		*sock;		/* Parent socket */
177
-	int			fd;		/* Parent fd, if tunnel socket
178
-						 * was created by userspace */
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
+						 */
179186 
180187 	struct work_struct	del_work;
181188 };
182189 
190
+/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
183191 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
+	 */
184198 	int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
185199 			      u32 session_id, u32 peer_session_id,
186200 			      struct l2tp_session_cfg *cfg);
187
-	int (*session_delete)(struct l2tp_session *session);
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);
188208 };
189209 
190210 static inline void *l2tp_session_priv(struct l2tp_session *session)
....@@ -192,73 +212,72 @@
192212 	return &session->priv[0];
193213 }
194214 
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
+ */
195225 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
196226 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
197227 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
198228 					     u32 session_id);
199
-
200
-void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
201229 
202230 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
203231 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
204232 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
205233 						const char *ifname);
206234 
207
-int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
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,
208240 		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
209241 		       struct l2tp_tunnel **tunnelp);
210242 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
211243 			 struct l2tp_tunnel_cfg *cfg);
212
-
213244 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
245
+
214246 struct l2tp_session *l2tp_session_create(int priv_size,
215247 					 struct l2tp_tunnel *tunnel,
216248 					 u32 session_id, u32 peer_session_id,
217249 					 struct l2tp_session_cfg *cfg);
218250 int l2tp_session_register(struct l2tp_session *session,
219251 			  struct l2tp_tunnel *tunnel);
252
+void l2tp_session_delete(struct l2tp_session *session);
220253 
221
-void __l2tp_session_unhash(struct l2tp_session *session);
222
-int l2tp_session_delete(struct l2tp_session *session);
223
-void l2tp_session_free(struct l2tp_session *session);
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
+ */
224258 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
225259 		      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
226260 		      int length);
227261 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
262
+
263
+/* Transmit path helpers for sending packets over the tunnel socket. */
228264 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
265
+int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb);
229266 
230
-int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
231
-		  int hdr_len);
232
-
233
-int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
234
-			 const struct l2tp_nl_cmd_ops *ops);
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);
235272 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
273
+
274
+/* IOCTL helper for IP encap modules. */
236275 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
237276 
238
-static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
239
-{
240
-	refcount_inc(&tunnel->ref_count);
241
-}
242
-
243
-static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
244
-{
245
-	if (refcount_dec_and_test(&tunnel->ref_count))
246
-		l2tp_tunnel_free(tunnel);
247
-}
248
-
249
-/* Session reference counts. Incremented when code obtains a reference
250
- * to a session.
277
+/* Extract the tunnel structure from a socket's sk_user_data pointer,
278
+ * validating the tunnel magic feather.
251279  */
252
-static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
253
-{
254
-	refcount_inc(&session->ref_count);
255
-}
256
-
257
-static inline void l2tp_session_dec_refcount(struct l2tp_session *session)
258
-{
259
-	if (refcount_dec_and_test(&session->ref_count))
260
-		l2tp_session_free(session);
261
-}
280
+struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk);
262281 
263282 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
264283 {
....@@ -320,19 +339,6 @@
320339 
321340 	return 0;
322341 }
323
-
324
-#define l2tp_printk(ptr, type, func, fmt, ...)				\
325
-do {									\
326
-	if (((ptr)->debug) & (type))					\
327
-		func(fmt, ##__VA_ARGS__);				\
328
-} while (0)
329
-
330
-#define l2tp_warn(ptr, type, fmt, ...)					\
331
-	l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
332
-#define l2tp_info(ptr, type, fmt, ...)					\
333
-	l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
334
-#define l2tp_dbg(ptr, type, fmt, ...)					\
335
-	l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
336342 
337343 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
338344 	MODULE_ALIAS("net-l2tp-type-" __stringify(type))