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                     offset;         /* offset to payload */
  62         u16                     l2specific_len; /* Layer 2 specific length */
  63         u16                     l2specific_type; /* Layer 2 specific type */
  64         u8                      cookie[8];      /* optional cookie */
  65         int                     cookie_len;     /* 0, 4 or 8 bytes */
  66         u8                      peer_cookie[8]; /* peer's cookie */
  67         int                     peer_cookie_len; /* 0, 4 or 8 bytes */
  68         int                     reorder_timeout; /* configured reorder timeout
  69                                                   * (in jiffies) */
  70         int                     mtu;
  71         int                     mru;
  72         char                    *ifname;
  73 };
  74
  75 struct l2tp_session {
  76         int                     magic;          /* should be
  77                                                  * L2TP_SESSION_MAGIC */
  78         long                    dead;
  79
  80         struct l2tp_tunnel      *tunnel;        /* back pointer to tunnel
  81                                                  * context */
  82         u32                     session_id;
  83         u32                     peer_session_id;
  84         u8                      cookie[8];
  85         int                     cookie_len;
  86         u8                      peer_cookie[8];
  87         int                     peer_cookie_len;
  88         u16                     offset;         /* offset from end of L2TP header
  89                                                    to beginning of data */
  90         u16                     l2specific_len;
  91         u16                     l2specific_type;
  92         u16                     hdr_len;
  93         u32                     nr;             /* session NR state (receive) */
  94         u32                     ns;             /* session NR state (send) */
  95         struct sk_buff_head     reorder_q;      /* receive reorder queue */
  96         u32                     nr_max;         /* max NR. Depends on tunnel */
  97         u32                     nr_window_size; /* NR window size */
  98         u32                     nr_oos;         /* NR of last OOS packet */
  99         int                     nr_oos_count;   /* For OOS recovery */
 100         int                     nr_oos_count_max;
 101         struct hlist_node       hlist;          /* Hash list node */
 102         atomic_t                ref_count;
 103
 104         char                    name[32];       /* for logging */
 105         char                    ifname[IFNAMSIZ];
 106         unsigned int            data_seq:2;     /* data sequencing level
 107                                                  * 0 => none, 1 => IP only,
 108                                                  * 2 => all
 109                                                  */
 110         unsigned int            recv_seq:1;     /* expect receive packets with
 111                                                  * sequence numbers? */
 112         unsigned int            send_seq:1;     /* send packets with sequence
 113                                                  * numbers? */
 114         unsigned int            lns_mode:1;     /* behave as LNS? LAC enables
 115                                                  * sequence numbers under
 116                                                  * control of LNS. */
 117         int                     debug;          /* bitmask of debug message
 118                                                  * categories */
 119         int                     reorder_timeout; /* configured reorder timeout
 120                                                   * (in jiffies) */
 121         int                     reorder_skip;   /* set if skip to next nr */
 122         int                     mtu;
 123         int                     mru;
 124         enum l2tp_pwtype        pwtype;
 125         struct l2tp_stats       stats;
 126         struct hlist_node       global_hlist;   /* Global hash list node */
 127
 128         int (*build_header)(struct l2tp_session *session, void *buf);
 129         void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 130         void (*session_close)(struct l2tp_session *session);
 131         void (*ref)(struct l2tp_session *session);
 132         void (*deref)(struct l2tp_session *session);
 133 #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
 134         void (*show)(struct seq_file *m, void *priv);
 135 #endif
 136         uint8_t                 priv[0];        /* private data */
 137 };
 138
 139 /* Describes the tunnel. It contains info to track all the associated
 140  * sessions so incoming packets can be sorted out
 141  */
 142 struct l2tp_tunnel_cfg {
 143         int                     debug;          /* bitmask of debug message
 144                                                  * categories */
 145         enum l2tp_encap_type    encap;
 146
 147         /* Used only for kernel-created sockets */
 148         struct in_addr          local_ip;
 149         struct in_addr          peer_ip;
 150 #if IS_ENABLED(CONFIG_IPV6)
 151         struct in6_addr         *local_ip6;
 152         struct in6_addr         *peer_ip6;
 153 #endif
 154         u16                     local_udp_port;
 155         u16                     peer_udp_port;
 156         unsigned int            use_udp_checksums:1,
 157                                 udp6_zero_tx_checksums:1,
 158                                 udp6_zero_rx_checksums:1;
 159 };
 160
 161 struct l2tp_tunnel {
 162         int                     magic;          /* Should be L2TP_TUNNEL_MAGIC */
 163
 164         unsigned long           dead;
 165
 166         struct rcu_head rcu;
 167         rwlock_t                hlist_lock;     /* protect session_hlist */
 168         bool                    acpt_newsess;   /* Indicates whether this
 169                                                  * tunnel accepts new sessions.
 170                                                  * Protected by hlist_lock.
 171                                                  */
 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
 206 struct l2tp_nl_cmd_ops {
 207         int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 208                               u32 session_id, u32 peer_session_id,
 209                               struct l2tp_session_cfg *cfg);
 210         int (*session_delete)(struct l2tp_session *session);
 211 };
 212
 213 static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
 214 {
 215         return &tunnel->priv[0];
 216 }
 217
 218 static inline void *l2tp_session_priv(struct l2tp_session *session)
 219 {
 220         return &session->priv[0];
 221 }
 222
 223 static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
 224 {
 225         struct l2tp_tunnel *tunnel;
 226
 227         if (sk == NULL)
 228                 return NULL;
 229
 230         sock_hold(sk);
 231         tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
 232         if (tunnel == NULL) {
 233                 sock_put(sk);
 234                 goto out;
 235         }
 236
 237         BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
 238
 239 out:
 240         return tunnel;
 241 }
 242
 243 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 244
 245 struct l2tp_session *l2tp_session_get(const struct net *net,
 246                                       struct l2tp_tunnel *tunnel,
 247                                       u32 session_id, bool do_ref);
 248 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 249                                           bool do_ref);
 250 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 251                                                 const char *ifname,
 252                                                 bool do_ref);
 253 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
 254 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
 255
 256 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 257                        u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 258                        struct l2tp_tunnel **tunnelp);
 259 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 260 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 261 struct l2tp_session *l2tp_session_create(int priv_size,
 262                                          struct l2tp_tunnel *tunnel,
 263                                          u32 session_id, u32 peer_session_id,
 264                                          struct l2tp_session_cfg *cfg);
 265 int l2tp_session_register(struct l2tp_session *session,
 266                           struct l2tp_tunnel *tunnel);
 267
 268 void __l2tp_session_unhash(struct l2tp_session *session);
 269 int l2tp_session_delete(struct l2tp_session *session);
 270 void l2tp_session_free(struct l2tp_session *session);
 271 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 272                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 273                       int length, int (*payload_hook)(struct sk_buff *skb));
 274 int l2tp_session_queue_purge(struct l2tp_session *session);
 275 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 276 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 277
 278 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 279                   int hdr_len);
 280
 281 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 282                          const struct l2tp_nl_cmd_ops *ops);
 283 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 284 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 285
 286 static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
 287 {
 288         atomic_inc(&tunnel->ref_count);
 289 }
 290
 291 static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
 292 {
 293         if (atomic_dec_and_test(&tunnel->ref_count))
 294                 kfree_rcu(tunnel, rcu);
 295 }
 296
 297 /* Session reference counts. Incremented when code obtains a reference
 298  * to a session.
 299  */
 300 static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
 301 {
 302         atomic_inc(&session->ref_count);
 303 }
 304
 305 static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
 306 {
 307         if (atomic_dec_and_test(&session->ref_count))
 308                 l2tp_session_free(session);
 309 }
 310
 311 #ifdef L2TP_REFCNT_DEBUG
 312 #define l2tp_session_inc_refcount(_s)                                   \
 313 do {                                                                    \
 314         pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n",       \
 315                  __func__, __LINE__, (_s)->name,                        \
 316                  atomic_read(&_s->ref_count));                          \
 317         l2tp_session_inc_refcount_1(_s);                                \
 318 } while (0)
 319 #define l2tp_session_dec_refcount(_s)                                   \
 320 do {                                                                    \
 321         pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n",       \
 322                  __func__, __LINE__, (_s)->name,                        \
 323                  atomic_read(&_s->ref_count));                          \
 324         l2tp_session_dec_refcount_1(_s);                                \
 325 } while (0)
 326 #else
 327 #define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
 328 #define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
 329 #endif
 330
 331 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 332 {
 333         switch (session->l2specific_type) {
 334         case L2TP_L2SPECTYPE_DEFAULT:
 335                 return 4;
 336         case L2TP_L2SPECTYPE_NONE:
 337         default:
 338                 return 0;
 339         }
 340 }
 341
 342 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 343                                                unsigned char **ptr, unsigned char **optr)
 344 {
 345         int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
 346
 347         if (opt_len > 0) {
 348                 int off = *ptr - *optr;
 349
 350                 if (!pskb_may_pull(skb, off + opt_len))
 351                         return -1;
 352
 353                 if (skb->data != *optr) {
 354                         *optr = skb->data;
 355                         *ptr = skb->data + off;
 356                 }
 357         }
 358
 359         return 0;
 360 }
 361
 362 #define l2tp_printk(ptr, type, func, fmt, ...)                          \
 363 do {                                                                    \
 364         if (((ptr)->debug) & (type))                                    \
 365                 func(fmt, ##__VA_ARGS__);                               \
 366 } while (0)
 367
 368 #define l2tp_warn(ptr, type, fmt, ...)                                  \
 369         l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
 370 #define l2tp_info(ptr, type, fmt, ...)                                  \
 371         l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
 372 #define l2tp_dbg(ptr, type, fmt, ...)                                   \
 373         l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
 374
 375 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 376         MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 377
 378 #endif /* _L2TP_CORE_H_ */