net/l2tp/l2tp_core.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /* L2TP internal definitions.
   3  *
   4  * Copyright (c) 2008,2009 Katalix Systems Ltd
   5  */
   6 #include <linux/refcount.h>
   7
   8 #ifndef _L2TP_CORE_H_
   9 #define _L2TP_CORE_H_
  10
  11 #include <net/dst.h>
  12 #include <net/sock.h>
  13
  14 #ifdef CONFIG_XFRM
  15 #include <net/xfrm.h>
  16 #endif
  17
  18 /* Just some random numbers */
  19 #define L2TP_TUNNEL_MAGIC       0x42114DDA
  20 #define L2TP_SESSION_MAGIC      0x0C04EB7D
  21
  22 /* Per tunnel, session hash table size */
  23 #define L2TP_HASH_BITS  4
  24 #define L2TP_HASH_SIZE  BIT(L2TP_HASH_BITS)
  25
  26 /* System-wide, session hash table size */
  27 #define L2TP_HASH_BITS_2        8
  28 #define L2TP_HASH_SIZE_2        BIT(L2TP_HASH_BITS_2)
  29
  30 struct sk_buff;
  31
  32 struct l2tp_stats {
  33         atomic_long_t           tx_packets;
  34         atomic_long_t           tx_bytes;
  35         atomic_long_t           tx_errors;
  36         atomic_long_t           rx_packets;
  37         atomic_long_t           rx_bytes;
  38         atomic_long_t           rx_seq_discards;
  39         atomic_long_t           rx_oos_packets;
  40         atomic_long_t           rx_errors;
  41         atomic_long_t           rx_cookie_discards;
  42 };
  43
  44 struct l2tp_tunnel;
  45
  46 /* Describes a session. Contains information to determine incoming
  47  * packets and transmit outgoing ones.
  48  */
  49 struct l2tp_session_cfg {
  50         enum l2tp_pwtype        pw_type;
  51         unsigned int            recv_seq:1;     /* expect receive packets with sequence numbers? */
  52         unsigned int            send_seq:1;     /* send packets with sequence numbers? */
  53         unsigned int            lns_mode:1;     /* behave as LNS?
  54                                                  * LAC enables sequence numbers under LNS control.
  55                                                  */
  56         int                     debug;          /* bitmask of debug message categories */
  57         u16                     l2specific_type; /* Layer 2 specific type */
  58         u8                      cookie[8];      /* optional cookie */
  59         int                     cookie_len;     /* 0, 4 or 8 bytes */
  60         u8                      peer_cookie[8]; /* peer's cookie */
  61         int                     peer_cookie_len; /* 0, 4 or 8 bytes */
  62         int                     reorder_timeout; /* configured reorder timeout (in jiffies) */
  63         char                    *ifname;
  64 };
  65
  66 struct l2tp_session {
  67         int                     magic;          /* should be L2TP_SESSION_MAGIC */
  68         long                    dead;
  69
  70         struct l2tp_tunnel      *tunnel;        /* back pointer to tunnel context */
  71         u32                     session_id;
  72         u32                     peer_session_id;
  73         u8                      cookie[8];
  74         int                     cookie_len;
  75         u8                      peer_cookie[8];
  76         int                     peer_cookie_len;
  77         u16                     l2specific_type;
  78         u16                     hdr_len;
  79         u32                     nr;             /* session NR state (receive) */
  80         u32                     ns;             /* session NR state (send) */
  81         struct sk_buff_head     reorder_q;      /* receive reorder queue */
  82         u32                     nr_max;         /* max NR. Depends on tunnel */
  83         u32                     nr_window_size; /* NR window size */
  84         u32                     nr_oos;         /* NR of last OOS packet */
  85         int                     nr_oos_count;   /* for OOS recovery */
  86         int                     nr_oos_count_max;
  87         struct hlist_node       hlist;          /* hash list node */
  88         refcount_t              ref_count;
  89
  90         char                    name[32];       /* for logging */
  91         char                    ifname[IFNAMSIZ];
  92         unsigned int            recv_seq:1;     /* expect receive packets with sequence numbers? */
  93         unsigned int            send_seq:1;     /* send packets with sequence numbers? */
  94         unsigned int            lns_mode:1;     /* behave as LNS?
  95                                                  * LAC enables sequence numbers under LNS control.
  96                                                  */
  97         int                     debug;          /* bitmask of debug message categories */
  98         int                     reorder_timeout; /* configured reorder timeout (in jiffies) */
  99         int                     reorder_skip;   /* set if skip to next nr */
 100         enum l2tp_pwtype        pwtype;
 101         struct l2tp_stats       stats;
 102         struct hlist_node       global_hlist;   /* global hash list node */
 103
 104         int (*build_header)(struct l2tp_session *session, void *buf);
 105         void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 106         void (*session_close)(struct l2tp_session *session);
 107         void (*show)(struct seq_file *m, void *priv);
 108         u8                      priv[];         /* private data */
 109 };
 110
 111 /* Describes the tunnel. It contains info to track all the associated
 112  * sessions so incoming packets can be sorted out
 113  */
 114 struct l2tp_tunnel_cfg {
 115         int                     debug;          /* bitmask of debug message categories */
 116         enum l2tp_encap_type    encap;
 117
 118         /* Used only for kernel-created sockets */
 119         struct in_addr          local_ip;
 120         struct in_addr          peer_ip;
 121 #if IS_ENABLED(CONFIG_IPV6)
 122         struct in6_addr         *local_ip6;
 123         struct in6_addr         *peer_ip6;
 124 #endif
 125         u16                     local_udp_port;
 126         u16                     peer_udp_port;
 127         unsigned int            use_udp_checksums:1,
 128                                 udp6_zero_tx_checksums:1,
 129                                 udp6_zero_rx_checksums:1;
 130 };
 131
 132 struct l2tp_tunnel {
 133         int                     magic;          /* Should be L2TP_TUNNEL_MAGIC */
 134
 135         unsigned long           dead;
 136
 137         struct rcu_head rcu;
 138         rwlock_t                hlist_lock;     /* protect session_hlist */
 139         bool                    acpt_newsess;   /* indicates whether this tunnel accepts
 140                                                  * new sessions. Protected by hlist_lock.
 141                                                  */
 142         struct hlist_head       session_hlist[L2TP_HASH_SIZE];
 143                                                 /* hashed list of sessions, hashed by id */
 144         u32                     tunnel_id;
 145         u32                     peer_tunnel_id;
 146         int                     version;        /* 2=>L2TPv2, 3=>L2TPv3 */
 147
 148         char                    name[20];       /* for logging */
 149         int                     debug;          /* bitmask of debug message categories */
 150         enum l2tp_encap_type    encap;
 151         struct l2tp_stats       stats;
 152
 153         struct list_head        list;           /* list node on per-namespace list of tunnels */
 154         struct net              *l2tp_net;      /* the net we belong to */
 155
 156         refcount_t              ref_count;
 157         void (*old_sk_destruct)(struct sock *sk);
 158         struct sock             *sock;          /* parent socket */
 159         int                     fd;             /* parent fd, if tunnel socket was created
 160                                                  * by userspace
 161                                                  */
 162
 163         struct work_struct      del_work;
 164 };
 165
 166 struct l2tp_nl_cmd_ops {
 167         int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 168                               u32 session_id, u32 peer_session_id,
 169                               struct l2tp_session_cfg *cfg);
 170         int (*session_delete)(struct l2tp_session *session);
 171 };
 172
 173 static inline void *l2tp_session_priv(struct l2tp_session *session)
 174 {
 175         return &session->priv[0];
 176 }
 177
 178 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 179 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 180 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 181                                              u32 session_id);
 182
 183 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
 184
 185 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
 186 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 187 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 188                                                 const char *ifname);
 189
 190 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 191                        u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 192                        struct l2tp_tunnel **tunnelp);
 193 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 194                          struct l2tp_tunnel_cfg *cfg);
 195
 196 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 197 struct l2tp_session *l2tp_session_create(int priv_size,
 198                                          struct l2tp_tunnel *tunnel,
 199                                          u32 session_id, u32 peer_session_id,
 200                                          struct l2tp_session_cfg *cfg);
 201 int l2tp_session_register(struct l2tp_session *session,
 202                           struct l2tp_tunnel *tunnel);
 203
 204 void __l2tp_session_unhash(struct l2tp_session *session);
 205 int l2tp_session_delete(struct l2tp_session *session);
 206 void l2tp_session_free(struct l2tp_session *session);
 207 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 208                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 209                       int length);
 210 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 211 void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 212
 213 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 214                   int hdr_len);
 215
 216 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 217                          const struct l2tp_nl_cmd_ops *ops);
 218 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 219 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 220
 221 static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
 222 {
 223         refcount_inc(&tunnel->ref_count);
 224 }
 225
 226 static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
 227 {
 228         if (refcount_dec_and_test(&tunnel->ref_count))
 229                 l2tp_tunnel_free(tunnel);
 230 }
 231
 232 /* Session reference counts. Incremented when code obtains a reference
 233  * to a session.
 234  */
 235 static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
 236 {
 237         refcount_inc(&session->ref_count);
 238 }
 239
 240 static inline void l2tp_session_dec_refcount(struct l2tp_session *session)
 241 {
 242         if (refcount_dec_and_test(&session->ref_count))
 243                 l2tp_session_free(session);
 244 }
 245
 246 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 247 {
 248         switch (session->l2specific_type) {
 249         case L2TP_L2SPECTYPE_DEFAULT:
 250                 return 4;
 251         case L2TP_L2SPECTYPE_NONE:
 252         default:
 253                 return 0;
 254         }
 255 }
 256
 257 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)
 258 {
 259         struct dst_entry *dst;
 260         u32 mtu;
 261
 262         dst = sk_dst_get(tunnel->sock);
 263         if (!dst)
 264                 return 0;
 265
 266         mtu = dst_mtu(dst);
 267         dst_release(dst);
 268
 269         return mtu;
 270 }
 271
 272 #ifdef CONFIG_XFRM
 273 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 274 {
 275         struct sock *sk = tunnel->sock;
 276
 277         return sk && (rcu_access_pointer(sk->sk_policy[0]) ||
 278                       rcu_access_pointer(sk->sk_policy[1]));
 279 }
 280 #else
 281 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 282 {
 283         return false;
 284 }
 285 #endif
 286
 287 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb,
 288                                                unsigned char **ptr, unsigned char **optr)
 289 {
 290         int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session);
 291
 292         if (opt_len > 0) {
 293                 int off = *ptr - *optr;
 294
 295                 if (!pskb_may_pull(skb, off + opt_len))
 296                         return -1;
 297
 298                 if (skb->data != *optr) {
 299                         *optr = skb->data;
 300                         *ptr = skb->data + off;
 301                 }
 302         }
 303
 304         return 0;
 305 }
 306
 307 #define l2tp_printk(ptr, type, func, fmt, ...)                          \
 308 do {                                                                    \
 309         if (((ptr)->debug) & (type))                                    \
 310                 func(fmt, ##__VA_ARGS__);                               \
 311 } while (0)
 312
 313 #define l2tp_warn(ptr, type, fmt, ...)                                  \
 314         l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
 315 #define l2tp_info(ptr, type, fmt, ...)                                  \
 316         l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
 317 #define l2tp_dbg(ptr, type, fmt, ...)                                   \
 318         l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
 319
 320 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 321         MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 322
 323 #endif /* _L2TP_CORE_H_ */