LXR linux/net/l2tp/l2tp

   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
  31struct sk_buff;
  32
  33struct 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
  45struct l2tp_tunnel;
  46
  47/* Describes a session. Contains information to determine incoming
  48 * packets and transmit outgoing ones.
  49 */
  50struct 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
  71struct 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 */
 125struct 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
 144struct 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
 180struct 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
 187static inline void *l2tp_session_priv(struct l2tp_session *session)
 188{
 189        return &session->priv[0];
 190}
 191
 192struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 193struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 194struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 195                                             u32 session_id);
 196
 197void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
 198
 199struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
 200struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 201struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 202                                                const char *ifname);
 203
 204int 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);
 207int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 208                         struct l2tp_tunnel_cfg *cfg);
 209
 210void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 211struct 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);
 215int l2tp_session_register(struct l2tp_session *session,
 216                          struct l2tp_tunnel *tunnel);
 217
 218void __l2tp_session_unhash(struct l2tp_session *session);
 219int l2tp_session_delete(struct l2tp_session *session);
 220void l2tp_session_free(struct l2tp_session *session);
 221void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 222                      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 223                      int length);
 224int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 225void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 226
 227int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 228                  int hdr_len);
 229
 230int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 231                         const struct l2tp_nl_cmd_ops *ops);
 232void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 233int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 234
 235static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
 236{
 237        refcount_inc(&tunnel->ref_count);
 238}
 239
 240static 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 */
 249static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
 250{
 251        refcount_inc(&session->ref_count);
 252}
 253
 254static 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
 260static 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
 271static 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
 287static 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
 295static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel)
 296{
 297        return false;
 298}
 299#endif
 300
 301static 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, ...)                          \
 322do {                                                                    \
 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_ */
 338