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 #include <net/dst.h>
  16 #include <net/sock.h>
  17
  18 #ifdef CONFIG_XFRM
  19 #include <net/xfrm.h>
  20 #endif
  21
  22 /* Just some random numbers */
  23 #define L2TP_TUNNEL_MAGIC       0x42114DDA
  24 #define L2TP_SESSION_MAGIC      0x0C04EB7D
  25
  26 /* Per tunnel, session hash table size */
  27 #define L2TP_HASH_BITS  4
  28 #define L2TP_HASH_SIZE  (1 << L2TP_HASH_BITS)
  29
  30 /* System-wide, session hash table size */
  31 #define L2TP_HASH_BITS_2        8
  32 #define L2TP_HASH_SIZE_2        (1 << L2TP_HASH_BITS_2)
  33
  34 struct sk_buff;
  35
  36 struct l2tp_stats {
  37         atomic_long_t           tx_packets;
  38         atomic_long_t           tx_bytes;
  39         atomic_long_t           tx_errors;
  40         atomic_long_t           rx_packets;
  41         atomic_long_t           rx_bytes;
  42         atomic_long_t           rx_seq_discards;
  43         atomic_long_t           rx_oos_packets;
  44         atomic_long_t           rx_errors;
  45         atomic_long_t           rx_cookie_discards;
  46 };
  47
  48 struct l2tp_tunnel;
  49
  50 /* Describes a session. Contains information to determine incoming
  51  * packets and transmit outgoing ones.
  52  */
  53 struct l2tp_session_cfg {
  54         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 */
  64         u16                     l2specific_type; /* Layer 2 specific type */
  65         u8                      cookie[8];      /* optional cookie */
  66         int                     cookie_len;     /* 0, 4 or 8 bytes */
  67         u8                      peer_cookie[8]; /* peer's cookie */
  68         int                     peer_cookie_len; /* 0, 4 or 8 bytes */
  69         int                     reorder_timeout; /* configured reorder timeout
  70                                                   * (in jiffies) */
  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_type;
  88         u16                     hdr_len;
  89         u32                     nr;             /* session NR state (receive) */
  90         u32                     ns;             /* session NR state (send) */
  91         struct sk_buff_head     reorder_q;      /* receive reorder queue */
  92         u32                     nr_max;         /* max NR. Depends on tunnel */
  93         u32                     nr_window_size; /* NR window size */
  94         u32                     nr_oos;         /* NR of last OOS packet */
  95         int                     nr_oos_count;   /* For OOS recovery */
  96         int                     nr_oos_count_max;
  97         struct hlist_node       hlist;          /* Hash list node */
  98         refcount_t              ref_count;
  99
 100         char                    name[32];       /* for logging */
 101         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) */
 113         int                     reorder_skip;   /* set if skip to next nr */
 114         enum l2tp_pwtype        pwtype;
 115         struct l2tp_stats       stats;
 116         struct hlist_node       global_hlist;   /* Global hash list node */
 117
 118         int (*build_header)(struct l2tp_session *session, void *buf);
 119         void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 120         void (*session_close)(struct l2tp_session *session);
 121         void (*show)(struct seq_file *m, void *priv);
 122         uint8_t                 priv[0];        /* private data */
 123 };
 124
 125 /* Describes the tunnel. It contains info to track all the associated
 126  * sessions so incoming packets can be sorted out
 127  */
 128 struct l2tp_tunnel_cfg {
 129         int                     debug;          /* bitmask of debug message
 130                                                  * categories */
 131         enum l2tp_encap_type    encap;
 132
 133         /* Used only for kernel-created sockets */
 134         struct in_addr          local_ip;
 135         struct in_addr          peer_ip;
 136 #if IS_ENABLED(CONFIG_IPV6)
 137         struct in6_addr         *local_ip6;
 138         struct in6_addr         *peer_ip6;
 139 #endif
 140         u16                     local_udp_port;
 141         u16                     peer_udp_port;
 142         unsigned int            use_udp_checksums:1,
 143                                 udp6_zero_tx_checksums:1,
 144                                 udp6_zero_rx_checksums:1;
 145 };
 146
 147 struct l2tp_tunnel {
 148         int                     magic;          /* Should be L2TP_TUNNEL_MAGIC */
 149
 150         unsigned long           dead;
 151
 152         struct rcu_head rcu;
 153         rwlock_t                hlist_lock;     /* protect session_hlist */
 154         bool                    acpt_newsess;   /* Indicates whether this
 155                                                  * tunnel accepts new sessions.
 156                                                  * Protected by hlist_lock.
 157                                                  */
 158         struct hlist_head       session_hlist[L2TP_HASH_SIZE];
 159                                                 /* hashed list of sessions,
 160                                                  * hashed by id */
 161         u32                     tunnel_id;
 162         u32                     peer_tunnel_id;
 163         int                     version;        /* 2=>L2TPv2, 3=>L2TPv3 */
 164
 165         char                    name[20];       /* for logging */
 166         int                     debug;          /* bitmask of debug message
 167                                                  * categories */
 168         enum l2tp_encap_type    encap;
 169         struct l2tp_stats       stats;
 170
 171         struct list_head        list;           /* Keep a list of all tunnels */
 172         struct net              *l2tp_net;      /* the net we belong to */
 173
 174         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 */
 179
 180         struct work_struct      del_work;
 181 };
 182
 183 struct l2tp_nl_cmd_ops {
 184         int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 185                               u32 session_id, u32 peer_session_id,
 186                               struct l2tp_session_cfg *cfg);
 187         int (*session_delete)(struct l2tp_session *session);
 188 };
 189
 190 static inline void *l2tp_session_priv(struct l2tp_session *session)
 191 {
 192         return &session->priv[0];
 193 }
 194
 195 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 196 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 197 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 198                                              u32 session_id);
 199
 200 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
 201
 202 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
 203 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 204 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 205                                                 const char *ifname);
 206
 207 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 208                        u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 209                        struct l2tp_tunnel **tunnelp);
 210 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 211                          struct l2tp_tunnel_cfg *cfg);
 212
 213 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 214 struct l2tp_session *l2tp_session_create(int priv_size,
 215                                          struct l2tp_tunnel *tunnel,
 216                                          u32 session_id, u32 peer_session_id,
 217                                          struct l2tp_session_cfg *cfg);
 218 int l2tp_session_register(struct l2tp_session *session,
 219                           struct l2tp_tunnel *tunnel);
 220
 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);
 224 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 225                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 226                       int length);
 227 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 228 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 229
 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);
 235 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 236 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 237
 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.
 251  */
 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 }
 262
 263 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 264 {
 265         switch (session->l2specific_type) {
 266         case L2TP_L2SPECTYPE_DEFAULT:
 267                 return 4;
 268         case L2TP_L2SPECTYPE_NONE:
 269         default:
 270                 return 0;
 271         }
 272 }
 273
 274 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
 275 {
 276         struct dst_entry *dst;
 277         u32 mtu;
 278
 279         dst = sk_dst_get(tunnel->sock);
 280         if (!dst)
 281                 return 0;
 282
 283         mtu = dst_mtu(dst);
 284         dst_release(dst);
 285
 286         return mtu;
 287 }
 288
 289 #ifdef CONFIG_XFRM
 290 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 291 {
 292         struct sock *sk = tunnel->sock;
 293
 294         return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
 295                       rcu_access_pointer(sk->sk_policy[1]));
 296 }
 297 #else
 298 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 299 {
 300         return false;
 301 }
 302 #endif
 303
 304 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 305                                                unsigned char **ptr, unsigned char **optr)
 306 {
 307         int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
 308
 309         if (opt_len > 0) {
 310                 int off = *ptr - *optr;
 311
 312                 if (!pskb_may_pull(skb, off + opt_len))
 313                         return -1;
 314
 315                 if (skb->data != *optr) {
 316                         *optr = skb->data;
 317                         *ptr = skb->data + off;
 318                 }
 319         }
 320
 321         return 0;
 322 }
 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__)
 336
 337 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 338         MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 339
 340 #endif /* _L2TP_CORE_H_ */