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 #include <linux/refcount.h>
  11
  12 #ifndef _L2TP_CORE_H_
  13 #define _L2TP_CORE_H_
  14
  15 /* Just some random numbers */
  16 #define L2TP_TUNNEL_MAGIC       0x42114DDA
  17 #define L2TP_SESSION_MAGIC      0x0C04EB7D
  18
  19 /* Per tunnel, session hash table size */
  20 #define L2TP_HASH_BITS  4
  21 #define L2TP_HASH_SIZE  (1 << L2TP_HASH_BITS)
  22
  23 /* System-wide, session hash table size */
  24 #define L2TP_HASH_BITS_2        8
  25 #define L2TP_HASH_SIZE_2        (1 << L2TP_HASH_BITS_2)
  26
  27 struct sk_buff;
  28
  29 struct l2tp_stats {
  30         atomic_long_t           tx_packets;
  31         atomic_long_t           tx_bytes;
  32         atomic_long_t           tx_errors;
  33         atomic_long_t           rx_packets;
  34         atomic_long_t           rx_bytes;
  35         atomic_long_t           rx_seq_discards;
  36         atomic_long_t           rx_oos_packets;
  37         atomic_long_t           rx_errors;
  38         atomic_long_t           rx_cookie_discards;
  39 };
  40
  41 struct l2tp_tunnel;
  42
  43 /* Describes a session. Contains information to determine incoming
  44  * packets and transmit outgoing ones.
  45  */
  46 struct l2tp_session_cfg {
  47         enum l2tp_pwtype        pw_type;
  48         unsigned int            data_seq:2;     /* data sequencing level
  49                                                  * 0 => none, 1 => IP only,
  50                                                  * 2 => all
  51                                                  */
  52         unsigned int            recv_seq:1;     /* expect receive packets with
  53                                                  * sequence numbers? */
  54         unsigned int            send_seq:1;     /* send packets with sequence
  55                                                  * numbers? */
  56         unsigned int            lns_mode:1;     /* behave as LNS? LAC enables
  57                                                  * sequence numbers under
  58                                                  * control of LNS. */
  59         int                     debug;          /* bitmask of debug message
  60                                                  * categories */
  61         u16                     vlan_id;        /* VLAN pseudowire only */
  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                     l2specific_len;
  89         u16                     l2specific_type;
  90         u16                     hdr_len;
  91         u32                     nr;             /* session NR state (receive) */
  92         u32                     ns;             /* session NR state (send) */
  93         struct sk_buff_head     reorder_q;      /* receive reorder queue */
  94         u32                     nr_max;         /* max NR. Depends on tunnel */
  95         u32                     nr_window_size; /* NR window size */
  96         u32                     nr_oos;         /* NR of last OOS packet */
  97         int                     nr_oos_count;   /* For OOS recovery */
  98         int                     nr_oos_count_max;
  99         struct hlist_node       hlist;          /* Hash list node */
 100         refcount_t              ref_count;
 101
 102         char                    name[32];       /* for logging */
 103         char                    ifname[IFNAMSIZ];
 104         unsigned int            data_seq:2;     /* data sequencing level
 105                                                  * 0 => none, 1 => IP only,
 106                                                  * 2 => all
 107                                                  */
 108         unsigned int            recv_seq:1;     /* expect receive packets with
 109                                                  * sequence numbers? */
 110         unsigned int            send_seq:1;     /* send packets with sequence
 111                                                  * numbers? */
 112         unsigned int            lns_mode:1;     /* behave as LNS? LAC enables
 113                                                  * sequence numbers under
 114                                                  * control of LNS. */
 115         int                     debug;          /* bitmask of debug message
 116                                                  * categories */
 117         int                     reorder_timeout; /* configured reorder timeout
 118                                                   * (in jiffies) */
 119         int                     reorder_skip;   /* set if skip to next nr */
 120         int                     mtu;
 121         int                     mru;
 122         enum l2tp_pwtype        pwtype;
 123         struct l2tp_stats       stats;
 124         struct hlist_node       global_hlist;   /* Global hash list node */
 125
 126         int (*build_header)(struct l2tp_session *session, void *buf);
 127         void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 128         void (*session_close)(struct l2tp_session *session);
 129         void (*ref)(struct l2tp_session *session);
 130         void (*deref)(struct l2tp_session *session);
 131 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 132         void (*show)(struct seq_file *m, void *priv);
 133 #endif
 134         uint8_t                 priv[0];        /* private data */
 135 };
 136
 137 /* Describes the tunnel. It contains info to track all the associated
 138  * sessions so incoming packets can be sorted out
 139  */
 140 struct l2tp_tunnel_cfg {
 141         int                     debug;          /* bitmask of debug message
 142                                                  * categories */
 143         enum l2tp_encap_type    encap;
 144
 145         /* Used only for kernel-created sockets */
 146         struct in_addr          local_ip;
 147         struct in_addr          peer_ip;
 148 #if IS_ENABLED(CONFIG_IPV6)
 149         struct in6_addr         *local_ip6;
 150         struct in6_addr         *peer_ip6;
 151 #endif
 152         u16                     local_udp_port;
 153         u16                     peer_udp_port;
 154         unsigned int            use_udp_checksums:1,
 155                                 udp6_zero_tx_checksums:1,
 156                                 udp6_zero_rx_checksums:1;
 157 };
 158
 159 struct l2tp_tunnel {
 160         int                     magic;          /* Should be L2TP_TUNNEL_MAGIC */
 161
 162         unsigned long           dead;
 163
 164         struct rcu_head rcu;
 165         rwlock_t                hlist_lock;     /* protect session_hlist */
 166         bool                    acpt_newsess;   /* Indicates whether this
 167                                                  * tunnel accepts new sessions.
 168                                                  * Protected by hlist_lock.
 169                                                  */
 170         struct hlist_head       session_hlist[L2TP_HASH_SIZE];
 171                                                 /* hashed list of sessions,
 172                                                  * hashed by id */
 173         u32                     tunnel_id;
 174         u32                     peer_tunnel_id;
 175         int                     version;        /* 2=>L2TPv2, 3=>L2TPv3 */
 176
 177         char                    name[20];       /* for logging */
 178         int                     debug;          /* bitmask of debug message
 179                                                  * categories */
 180         enum l2tp_encap_type    encap;
 181         struct l2tp_stats       stats;
 182
 183         struct list_head        list;           /* Keep a list of all tunnels */
 184         struct net              *l2tp_net;      /* the net we belong to */
 185
 186         refcount_t              ref_count;
 187 #ifdef CONFIG_DEBUG_FS
 188         void (*show)(struct seq_file *m, void *arg);
 189 #endif
 190         int (*recv_payload_hook)(struct sk_buff *skb);
 191         void (*old_sk_destruct)(struct sock *);
 192         struct sock             *sock;          /* Parent socket */
 193         int                     fd;             /* Parent fd, if tunnel socket
 194                                                  * was created by userspace */
 195
 196         struct work_struct      del_work;
 197
 198         uint8_t                 priv[0];        /* private data */
 199 };
 200
 201 struct l2tp_nl_cmd_ops {
 202         int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 203                               u32 session_id, u32 peer_session_id,
 204                               struct l2tp_session_cfg *cfg);
 205         int (*session_delete)(struct l2tp_session *session);
 206 };
 207
 208 static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
 209 {
 210         return &tunnel->priv[0];
 211 }
 212
 213 static inline void *l2tp_session_priv(struct l2tp_session *session)
 214 {
 215         return &session->priv[0];
 216 }
 217
 218 static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
 219 {
 220         struct l2tp_tunnel *tunnel;
 221
 222         if (sk == NULL)
 223                 return NULL;
 224
 225         sock_hold(sk);
 226         tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
 227         if (tunnel == NULL) {
 228                 sock_put(sk);
 229                 goto out;
 230         }
 231
 232         BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
 233
 234 out:
 235         return tunnel;
 236 }
 237
 238 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 239
 240 struct l2tp_session *l2tp_session_get(const struct net *net,
 241                                       struct l2tp_tunnel *tunnel,
 242                                       u32 session_id, bool do_ref);
 243 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 244                                           bool do_ref);
 245 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 246                                                 const char *ifname,
 247                                                 bool do_ref);
 248 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
 249 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
 250
 251 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 252                        u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 253                        struct l2tp_tunnel **tunnelp);
 254 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 255 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 256 struct l2tp_session *l2tp_session_create(int priv_size,
 257                                          struct l2tp_tunnel *tunnel,
 258                                          u32 session_id, u32 peer_session_id,
 259                                          struct l2tp_session_cfg *cfg);
 260 int l2tp_session_register(struct l2tp_session *session,
 261                           struct l2tp_tunnel *tunnel);
 262
 263 void __l2tp_session_unhash(struct l2tp_session *session);
 264 int l2tp_session_delete(struct l2tp_session *session);
 265 void l2tp_session_free(struct l2tp_session *session);
 266 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 267                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 268                       int length, int (*payload_hook)(struct sk_buff *skb));
 269 int l2tp_session_queue_purge(struct l2tp_session *session);
 270 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 271 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 272
 273 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 274                   int hdr_len);
 275
 276 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 277                          const struct l2tp_nl_cmd_ops *ops);
 278 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 279 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 280
 281 static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
 282 {
 283         refcount_inc(&tunnel->ref_count);
 284 }
 285
 286 static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
 287 {
 288         if (refcount_dec_and_test(&tunnel->ref_count))
 289                 kfree_rcu(tunnel, rcu);
 290 }
 291
 292 /* Session reference counts. Incremented when code obtains a reference
 293  * to a session.
 294  */
 295 static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
 296 {
 297         refcount_inc(&session->ref_count);
 298 }
 299
 300 static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
 301 {
 302         if (refcount_dec_and_test(&session->ref_count))
 303                 l2tp_session_free(session);
 304 }
 305
 306 #ifdef L2TP_REFCNT_DEBUG
 307 #define l2tp_session_inc_refcount(_s)                                   \
 308 do {                                                                    \
 309         pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n",       \
 310                  __func__, __LINE__, (_s)->name,                        \
 311                  refcount_read(&_s->ref_count));                        \
 312         l2tp_session_inc_refcount_1(_s);                                \
 313 } while (0)
 314 #define l2tp_session_dec_refcount(_s)                                   \
 315 do {                                                                    \
 316         pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n",       \
 317                  __func__, __LINE__, (_s)->name,                        \
 318                  refcount_read(&_s->ref_count));                        \
 319         l2tp_session_dec_refcount_1(_s);                                \
 320 } while (0)
 321 #else
 322 #define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
 323 #define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
 324 #endif
 325
 326 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 327 {
 328         switch (session->l2specific_type) {
 329         case L2TP_L2SPECTYPE_DEFAULT:
 330                 return 4;
 331         case L2TP_L2SPECTYPE_NONE:
 332         default:
 333                 return 0;
 334         }
 335 }
 336
 337 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 338                                                unsigned char **ptr, unsigned char **optr)
 339 {
 340         int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
 341
 342         if (opt_len > 0) {
 343                 int off = *ptr - *optr;
 344
 345                 if (!pskb_may_pull(skb, off + opt_len))
 346                         return -1;
 347
 348                 if (skb->data != *optr) {
 349                         *optr = skb->data;
 350                         *ptr = skb->data + off;
 351                 }
 352         }
 353
 354         return 0;
 355 }
 356
 357 #define l2tp_printk(ptr, type, func, fmt, ...)                          \
 358 do {                                                                    \
 359         if (((ptr)->debug) & (type))                                    \
 360                 func(fmt, ##__VA_ARGS__);                               \
 361 } while (0)
 362
 363 #define l2tp_warn(ptr, type, fmt, ...)                                  \
 364         l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
 365 #define l2tp_info(ptr, type, fmt, ...)                                  \
 366         l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
 367 #define l2tp_dbg(ptr, type, fmt, ...)                                   \
 368         l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
 369
 370 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 371         MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 372
 373 #endif /* _L2TP_CORE_H_ */