net/l2tp/l2tp_core.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * L2TP internal definitions.
   4  *
   5  * Copyright (c) 2008,2009 Katalix Systems Ltd
   6  */
   7 #include <linux/refcount.h>
   8
   9 #ifndef _L2TP_CORE_H_
  10 #define _L2TP_CORE_H_
  11
  12 #include <net/dst.h>
  13 #include <net/sock.h>
  14
  15 #ifdef CONFIG_XFRM
  16 #include <net/xfrm.h>
  17 #endif
  18
  19 /* Just some random numbers */
  20 #define L2TP_TUNNEL_MAGIC       0x42114DDA
  21 #define L2TP_SESSION_MAGIC      0x0C04EB7D
  22
  23 /* Per tunnel, session hash table size */
  24 #define L2TP_HASH_BITS  4
  25 #define L2TP_HASH_SIZE  (1 << L2TP_HASH_BITS)
  26
  27 /* System-wide, session hash table size */
  28 #define L2TP_HASH_BITS_2        8
  29 #define L2TP_HASH_SIZE_2        (1 << L2TP_HASH_BITS_2)
  30
  31 struct sk_buff;
  32
  33 struct l2tp_stats {
  34         atomic_long_t           tx_packets;
  35         atomic_long_t           tx_bytes;
  36         atomic_long_t           tx_errors;
  37         atomic_long_t           rx_packets;
  38         atomic_long_t           rx_bytes;
  39         atomic_long_t           rx_seq_discards;
  40         atomic_long_t           rx_oos_packets;
  41         atomic_long_t           rx_errors;
  42         atomic_long_t           rx_cookie_discards;
  43 };
  44
  45 struct l2tp_tunnel;
  46
  47 /* Describes a session. Contains information to determine incoming
  48  * packets and transmit outgoing ones.
  49  */
  50 struct l2tp_session_cfg {
  51         enum l2tp_pwtype        pw_type;
  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                     l2specific_type; /* Layer 2 specific type */
  62         u8                      cookie[8];      /* optional cookie */
  63         int                     cookie_len;     /* 0, 4 or 8 bytes */
  64         u8                      peer_cookie[8]; /* peer's cookie */
  65         int                     peer_cookie_len; /* 0, 4 or 8 bytes */
  66         int                     reorder_timeout; /* configured reorder timeout
  67                                                   * (in jiffies) */
  68         char                    *ifname;
  69 };
  70
  71 struct l2tp_session {
  72         int                     magic;          /* should be
  73                                                  * L2TP_SESSION_MAGIC */
  74         long                    dead;
  75
  76         struct l2tp_tunnel      *tunnel;        /* back pointer to tunnel
  77                                                  * context */
  78         u32                     session_id;
  79         u32                     peer_session_id;
  80         u8                      cookie[8];
  81         int                     cookie_len;
  82         u8                      peer_cookie[8];
  83         int                     peer_cookie_len;
  84         u16                     l2specific_type;
  85         u16                     hdr_len;
  86         u32                     nr;             /* session NR state (receive) */
  87         u32                     ns;             /* session NR state (send) */
  88         struct sk_buff_head     reorder_q;      /* receive reorder queue */
  89         u32                     nr_max;         /* max NR. Depends on tunnel */
  90         u32                     nr_window_size; /* NR window size */
  91         u32                     nr_oos;         /* NR of last OOS packet */
  92         int                     nr_oos_count;   /* For OOS recovery */
  93         int                     nr_oos_count_max;
  94         struct hlist_node       hlist;          /* Hash list node */
  95         refcount_t              ref_count;
  96
  97         char                    name[32];       /* for logging */
  98         char                    ifname[IFNAMSIZ];
  99         unsigned int            recv_seq:1;     /* expect receive packets with
 100                                                  * sequence numbers? */
 101         unsigned int            send_seq:1;     /* send packets with sequence
 102                                                  * numbers? */
 103         unsigned int            lns_mode:1;     /* behave as LNS? LAC enables
 104                                                  * sequence numbers under
 105                                                  * control of LNS. */
 106         int                     debug;          /* bitmask of debug message
 107                                                  * categories */
 108         int                     reorder_timeout; /* configured reorder timeout
 109                                                   * (in jiffies) */
 110         int                     reorder_skip;   /* set if skip to next nr */
 111         enum l2tp_pwtype        pwtype;
 112         struct l2tp_stats       stats;
 113         struct hlist_node       global_hlist;   /* Global hash list node */
 114
 115         int (*build_header)(struct l2tp_session *session, void *buf);
 116         void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 117         void (*session_close)(struct l2tp_session *session);
 118         void (*show)(struct seq_file *m, void *priv);
 119         uint8_t                 priv[0];        /* private data */
 120 };
 121
 122 /* Describes the tunnel. It contains info to track all the associated
 123  * sessions so incoming packets can be sorted out
 124  */
 125 struct l2tp_tunnel_cfg {
 126         int                     debug;          /* bitmask of debug message
 127                                                  * categories */
 128         enum l2tp_encap_type    encap;
 129
 130         /* Used only for kernel-created sockets */
 131         struct in_addr          local_ip;
 132         struct in_addr          peer_ip;
 133 #if IS_ENABLED(CONFIG_IPV6)
 134         struct in6_addr         *local_ip6;
 135         struct in6_addr         *peer_ip6;
 136 #endif
 137         u16                     local_udp_port;
 138         u16                     peer_udp_port;
 139         unsigned int            use_udp_checksums:1,
 140                                 udp6_zero_tx_checksums:1,
 141                                 udp6_zero_rx_checksums:1;
 142 };
 143
 144 struct l2tp_tunnel {
 145         int                     magic;          /* Should be L2TP_TUNNEL_MAGIC */
 146
 147         unsigned long           dead;
 148
 149         struct rcu_head rcu;
 150         rwlock_t                hlist_lock;     /* protect session_hlist */
 151         bool                    acpt_newsess;   /* Indicates whether this
 152                                                  * tunnel accepts new sessions.
 153                                                  * Protected by hlist_lock.
 154                                                  */
 155         struct hlist_head       session_hlist[L2TP_HASH_SIZE];
 156                                                 /* hashed list of sessions,
 157                                                  * hashed by id */
 158         u32                     tunnel_id;
 159         u32                     peer_tunnel_id;
 160         int                     version;        /* 2=>L2TPv2, 3=>L2TPv3 */
 161
 162         char                    name[20];       /* for logging */
 163         int                     debug;          /* bitmask of debug message
 164                                                  * categories */
 165         enum l2tp_encap_type    encap;
 166         struct l2tp_stats       stats;
 167
 168         struct list_head        list;           /* Keep a list of all tunnels */
 169         struct net              *l2tp_net;      /* the net we belong to */
 170
 171         refcount_t              ref_count;
 172         void (*old_sk_destruct)(struct sock *);
 173         struct sock             *sock;          /* Parent socket */
 174         int                     fd;             /* Parent fd, if tunnel socket
 175                                                  * was created by userspace */
 176
 177         struct work_struct      del_work;
 178 };
 179
 180 struct l2tp_nl_cmd_ops {
 181         int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 182                               u32 session_id, u32 peer_session_id,
 183                               struct l2tp_session_cfg *cfg);
 184         int (*session_delete)(struct l2tp_session *session);
 185 };
 186
 187 static inline void *l2tp_session_priv(struct l2tp_session *session)
 188 {
 189         return &session->priv[0];
 190 }
 191
 192 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 193 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 194 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 195                                              u32 session_id);
 196
 197 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
 198
 199 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
 200 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 201 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 202                                                 const char *ifname);
 203
 204 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 205                        u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 206                        struct l2tp_tunnel **tunnelp);
 207 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 208                          struct l2tp_tunnel_cfg *cfg);
 209
 210 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 211 struct l2tp_session *l2tp_session_create(int priv_size,
 212                                          struct l2tp_tunnel *tunnel,
 213                                          u32 session_id, u32 peer_session_id,
 214                                          struct l2tp_session_cfg *cfg);
 215 int l2tp_session_register(struct l2tp_session *session,
 216                           struct l2tp_tunnel *tunnel);
 217
 218 void __l2tp_session_unhash(struct l2tp_session *session);
 219 int l2tp_session_delete(struct l2tp_session *session);
 220 void l2tp_session_free(struct l2tp_session *session);
 221 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 222                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 223                       int length);
 224 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 225 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 226
 227 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 228                   int hdr_len);
 229
 230 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 231                          const struct l2tp_nl_cmd_ops *ops);
 232 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 233 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 234
 235 static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
 236 {
 237         refcount_inc(&tunnel->ref_count);
 238 }
 239
 240 static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
 241 {
 242         if (refcount_dec_and_test(&tunnel->ref_count))
 243                 l2tp_tunnel_free(tunnel);
 244 }
 245
 246 /* Session reference counts. Incremented when code obtains a reference
 247  * to a session.
 248  */
 249 static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
 250 {
 251         refcount_inc(&session->ref_count);
 252 }
 253
 254 static inline void l2tp_session_dec_refcount(struct l2tp_session *session)
 255 {
 256         if (refcount_dec_and_test(&session->ref_count))
 257                 l2tp_session_free(session);
 258 }
 259
 260 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 261 {
 262         switch (session->l2specific_type) {
 263         case L2TP_L2SPECTYPE_DEFAULT:
 264                 return 4;
 265         case L2TP_L2SPECTYPE_NONE:
 266         default:
 267                 return 0;
 268         }
 269 }
 270
 271 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
 272 {
 273         struct dst_entry *dst;
 274         u32 mtu;
 275
 276         dst = sk_dst_get(tunnel->sock);
 277         if (!dst)
 278                 return 0;
 279
 280         mtu = dst_mtu(dst);
 281         dst_release(dst);
 282
 283         return mtu;
 284 }
 285
 286 #ifdef CONFIG_XFRM
 287 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 288 {
 289         struct sock *sk = tunnel->sock;
 290
 291         return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
 292                       rcu_access_pointer(sk->sk_policy[1]));
 293 }
 294 #else
 295 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 296 {
 297         return false;
 298 }
 299 #endif
 300
 301 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 302                                                unsigned char **ptr, unsigned char **optr)
 303 {
 304         int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
 305
 306         if (opt_len > 0) {
 307                 int off = *ptr - *optr;
 308
 309                 if (!pskb_may_pull(skb, off + opt_len))
 310                         return -1;
 311
 312                 if (skb->data != *optr) {
 313                         *optr = skb->data;
 314                         *ptr = skb->data + off;
 315                 }
 316         }
 317
 318         return 0;
 319 }
 320
 321 #define l2tp_printk(ptr, type, func, fmt, ...)                          \
 322 do {                                                                    \
 323         if (((ptr)->debug) & (type))                                    \
 324                 func(fmt, ##__VA_ARGS__);                               \
 325 } while (0)
 326
 327 #define l2tp_warn(ptr, type, fmt, ...)                                  \
 328         l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
 329 #define l2tp_info(ptr, type, fmt, ...)                                  \
 330         l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
 331 #define l2tp_dbg(ptr, type, fmt, ...)                                   \
 332         l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
 333
 334 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 335         MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 336
 337 #endif /* _L2TP_CORE_H_ */