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