linux/include/net/neighbour.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _NET_NEIGHBOUR_H
   3#define _NET_NEIGHBOUR_H
   4
   5#include <linux/neighbour.h>
   6
   7/*
   8 *      Generic neighbour manipulation
   9 *
  10 *      Authors:
  11 *      Pedro Roque             <roque@di.fc.ul.pt>
  12 *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
  13 *
  14 *      Changes:
  15 *
  16 *      Harald Welte:           <laforge@gnumonks.org>
  17 *              - Add neighbour cache statistics like rtstat
  18 */
  19
  20#include <linux/atomic.h>
  21#include <linux/refcount.h>
  22#include <linux/netdevice.h>
  23#include <linux/skbuff.h>
  24#include <linux/rcupdate.h>
  25#include <linux/seq_file.h>
  26#include <linux/bitmap.h>
  27
  28#include <linux/err.h>
  29#include <linux/sysctl.h>
  30#include <linux/workqueue.h>
  31#include <net/rtnetlink.h>
  32
  33/*
  34 * NUD stands for "neighbor unreachability detection"
  35 */
  36
  37#define NUD_IN_TIMER    (NUD_INCOMPLETE|NUD_REACHABLE|NUD_DELAY|NUD_PROBE)
  38#define NUD_VALID       (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE|NUD_PROBE|NUD_STALE|NUD_DELAY)
  39#define NUD_CONNECTED   (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE)
  40
  41struct neighbour;
  42
  43enum {
  44        NEIGH_VAR_MCAST_PROBES,
  45        NEIGH_VAR_UCAST_PROBES,
  46        NEIGH_VAR_APP_PROBES,
  47        NEIGH_VAR_MCAST_REPROBES,
  48        NEIGH_VAR_RETRANS_TIME,
  49        NEIGH_VAR_BASE_REACHABLE_TIME,
  50        NEIGH_VAR_DELAY_PROBE_TIME,
  51        NEIGH_VAR_GC_STALETIME,
  52        NEIGH_VAR_QUEUE_LEN_BYTES,
  53        NEIGH_VAR_PROXY_QLEN,
  54        NEIGH_VAR_ANYCAST_DELAY,
  55        NEIGH_VAR_PROXY_DELAY,
  56        NEIGH_VAR_LOCKTIME,
  57#define NEIGH_VAR_DATA_MAX (NEIGH_VAR_LOCKTIME + 1)
  58        /* Following are used as a second way to access one of the above */
  59        NEIGH_VAR_QUEUE_LEN, /* same data as NEIGH_VAR_QUEUE_LEN_BYTES */
  60        NEIGH_VAR_RETRANS_TIME_MS, /* same data as NEIGH_VAR_RETRANS_TIME */
  61        NEIGH_VAR_BASE_REACHABLE_TIME_MS, /* same data as NEIGH_VAR_BASE_REACHABLE_TIME */
  62        /* Following are used by "default" only */
  63        NEIGH_VAR_GC_INTERVAL,
  64        NEIGH_VAR_GC_THRESH1,
  65        NEIGH_VAR_GC_THRESH2,
  66        NEIGH_VAR_GC_THRESH3,
  67        NEIGH_VAR_MAX
  68};
  69
  70struct neigh_parms {
  71        possible_net_t net;
  72        struct net_device *dev;
  73        struct list_head list;
  74        int     (*neigh_setup)(struct neighbour *);
  75        void    (*neigh_cleanup)(struct neighbour *);
  76        struct neigh_table *tbl;
  77
  78        void    *sysctl_table;
  79
  80        int dead;
  81        refcount_t refcnt;
  82        struct rcu_head rcu_head;
  83
  84        int     reachable_time;
  85        int     data[NEIGH_VAR_DATA_MAX];
  86        DECLARE_BITMAP(data_state, NEIGH_VAR_DATA_MAX);
  87};
  88
  89static inline void neigh_var_set(struct neigh_parms *p, int index, int val)
  90{
  91        set_bit(index, p->data_state);
  92        p->data[index] = val;
  93}
  94
  95#define NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr])
  96
  97/* In ndo_neigh_setup, NEIGH_VAR_INIT should be used.
  98 * In other cases, NEIGH_VAR_SET should be used.
  99 */
 100#define NEIGH_VAR_INIT(p, attr, val) (NEIGH_VAR(p, attr) = val)
 101#define NEIGH_VAR_SET(p, attr, val) neigh_var_set(p, NEIGH_VAR_ ## attr, val)
 102
 103static inline void neigh_parms_data_state_setall(struct neigh_parms *p)
 104{
 105        bitmap_fill(p->data_state, NEIGH_VAR_DATA_MAX);
 106}
 107
 108static inline void neigh_parms_data_state_cleanall(struct neigh_parms *p)
 109{
 110        bitmap_zero(p->data_state, NEIGH_VAR_DATA_MAX);
 111}
 112
 113struct neigh_statistics {
 114        unsigned long allocs;           /* number of allocated neighs */
 115        unsigned long destroys;         /* number of destroyed neighs */
 116        unsigned long hash_grows;       /* number of hash resizes */
 117
 118        unsigned long res_failed;       /* number of failed resolutions */
 119
 120        unsigned long lookups;          /* number of lookups */
 121        unsigned long hits;             /* number of hits (among lookups) */
 122
 123        unsigned long rcv_probes_mcast; /* number of received mcast ipv6 */
 124        unsigned long rcv_probes_ucast; /* number of received ucast ipv6 */
 125
 126        unsigned long periodic_gc_runs; /* number of periodic GC runs */
 127        unsigned long forced_gc_runs;   /* number of forced GC runs */
 128
 129        unsigned long unres_discards;   /* number of unresolved drops */
 130        unsigned long table_fulls;      /* times even gc couldn't help */
 131};
 132
 133#define NEIGH_CACHE_STAT_INC(tbl, field) this_cpu_inc((tbl)->stats->field)
 134
 135struct neighbour {
 136        struct neighbour __rcu  *next;
 137        struct neigh_table      *tbl;
 138        struct neigh_parms      *parms;
 139        unsigned long           confirmed;
 140        unsigned long           updated;
 141        rwlock_t                lock;
 142        refcount_t              refcnt;
 143        struct sk_buff_head     arp_queue;
 144        unsigned int            arp_queue_len_bytes;
 145        struct timer_list       timer;
 146        unsigned long           used;
 147        atomic_t                probes;
 148        __u8                    flags;
 149        __u8                    nud_state;
 150        __u8                    type;
 151        __u8                    dead;
 152        seqlock_t               ha_lock;
 153        unsigned char           ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
 154        struct hh_cache         hh;
 155        int                     (*output)(struct neighbour *, struct sk_buff *);
 156        const struct neigh_ops  *ops;
 157        struct rcu_head         rcu;
 158        struct net_device       *dev;
 159        u8                      primary_key[0];
 160} __randomize_layout;
 161
 162struct neigh_ops {
 163        int                     family;
 164        void                    (*solicit)(struct neighbour *, struct sk_buff *);
 165        void                    (*error_report)(struct neighbour *, struct sk_buff *);
 166        int                     (*output)(struct neighbour *, struct sk_buff *);
 167        int                     (*connected_output)(struct neighbour *, struct sk_buff *);
 168};
 169
 170struct pneigh_entry {
 171        struct pneigh_entry     *next;
 172        possible_net_t          net;
 173        struct net_device       *dev;
 174        u8                      flags;
 175        u8                      key[0];
 176};
 177
 178/*
 179 *      neighbour table manipulation
 180 */
 181
 182#define NEIGH_NUM_HASH_RND      4
 183
 184struct neigh_hash_table {
 185        struct neighbour __rcu  **hash_buckets;
 186        unsigned int            hash_shift;
 187        __u32                   hash_rnd[NEIGH_NUM_HASH_RND];
 188        struct rcu_head         rcu;
 189};
 190
 191
 192struct neigh_table {
 193        int                     family;
 194        unsigned int            entry_size;
 195        unsigned int            key_len;
 196        __be16                  protocol;
 197        __u32                   (*hash)(const void *pkey,
 198                                        const struct net_device *dev,
 199                                        __u32 *hash_rnd);
 200        bool                    (*key_eq)(const struct neighbour *, const void *pkey);
 201        int                     (*constructor)(struct neighbour *);
 202        int                     (*pconstructor)(struct pneigh_entry *);
 203        void                    (*pdestructor)(struct pneigh_entry *);
 204        void                    (*proxy_redo)(struct sk_buff *skb);
 205        char                    *id;
 206        struct neigh_parms      parms;
 207        struct list_head        parms_list;
 208        int                     gc_interval;
 209        int                     gc_thresh1;
 210        int                     gc_thresh2;
 211        int                     gc_thresh3;
 212        unsigned long           last_flush;
 213        struct delayed_work     gc_work;
 214        struct timer_list       proxy_timer;
 215        struct sk_buff_head     proxy_queue;
 216        atomic_t                entries;
 217        rwlock_t                lock;
 218        unsigned long           last_rand;
 219        struct neigh_statistics __percpu *stats;
 220        struct neigh_hash_table __rcu *nht;
 221        struct pneigh_entry     **phash_buckets;
 222};
 223
 224enum {
 225        NEIGH_ARP_TABLE = 0,
 226        NEIGH_ND_TABLE = 1,
 227        NEIGH_DN_TABLE = 2,
 228        NEIGH_NR_TABLES,
 229        NEIGH_LINK_TABLE = NEIGH_NR_TABLES /* Pseudo table for neigh_xmit */
 230};
 231
 232static inline int neigh_parms_family(struct neigh_parms *p)
 233{
 234        return p->tbl->family;
 235}
 236
 237#define NEIGH_PRIV_ALIGN        sizeof(long long)
 238#define NEIGH_ENTRY_SIZE(size)  ALIGN((size), NEIGH_PRIV_ALIGN)
 239
 240static inline void *neighbour_priv(const struct neighbour *n)
 241{
 242        return (char *)n + n->tbl->entry_size;
 243}
 244
 245/* flags for neigh_update() */
 246#define NEIGH_UPDATE_F_OVERRIDE                 0x00000001
 247#define NEIGH_UPDATE_F_WEAK_OVERRIDE            0x00000002
 248#define NEIGH_UPDATE_F_OVERRIDE_ISROUTER        0x00000004
 249#define NEIGH_UPDATE_F_ISROUTER                 0x40000000
 250#define NEIGH_UPDATE_F_ADMIN                    0x80000000
 251
 252
 253static inline bool neigh_key_eq16(const struct neighbour *n, const void *pkey)
 254{
 255        return *(const u16 *)n->primary_key == *(const u16 *)pkey;
 256}
 257
 258static inline bool neigh_key_eq32(const struct neighbour *n, const void *pkey)
 259{
 260        return *(const u32 *)n->primary_key == *(const u32 *)pkey;
 261}
 262
 263static inline bool neigh_key_eq128(const struct neighbour *n, const void *pkey)
 264{
 265        const u32 *n32 = (const u32 *)n->primary_key;
 266        const u32 *p32 = pkey;
 267
 268        return ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
 269                (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0;
 270}
 271
 272static inline struct neighbour *___neigh_lookup_noref(
 273        struct neigh_table *tbl,
 274        bool (*key_eq)(const struct neighbour *n, const void *pkey),
 275        __u32 (*hash)(const void *pkey,
 276                      const struct net_device *dev,
 277                      __u32 *hash_rnd),
 278        const void *pkey,
 279        struct net_device *dev)
 280{
 281        struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht);
 282        struct neighbour *n;
 283        u32 hash_val;
 284
 285        hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
 286        for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
 287             n != NULL;
 288             n = rcu_dereference_bh(n->next)) {
 289                if (n->dev == dev && key_eq(n, pkey))
 290                        return n;
 291        }
 292
 293        return NULL;
 294}
 295
 296static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl,
 297                                                     const void *pkey,
 298                                                     struct net_device *dev)
 299{
 300        return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev);
 301}
 302
 303void neigh_table_init(int index, struct neigh_table *tbl);
 304int neigh_table_clear(int index, struct neigh_table *tbl);
 305struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
 306                               struct net_device *dev);
 307struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
 308                                     const void *pkey);
 309struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
 310                                 struct net_device *dev, bool want_ref);
 311static inline struct neighbour *neigh_create(struct neigh_table *tbl,
 312                                             const void *pkey,
 313                                             struct net_device *dev)
 314{
 315        return __neigh_create(tbl, pkey, dev, true);
 316}
 317void neigh_destroy(struct neighbour *neigh);
 318int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
 319int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags,
 320                 u32 nlmsg_pid);
 321void __neigh_set_probe_once(struct neighbour *neigh);
 322bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl);
 323void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
 324int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 325int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
 326int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
 327int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
 328struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 329                                                u8 *lladdr, void *saddr,
 330                                                struct net_device *dev);
 331
 332struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 333                                      struct neigh_table *tbl);
 334void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);
 335
 336static inline
 337struct net *neigh_parms_net(const struct neigh_parms *parms)
 338{
 339        return read_pnet(&parms->net);
 340}
 341
 342unsigned long neigh_rand_reach_time(unsigned long base);
 343
 344void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 345                    struct sk_buff *skb);
 346struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
 347                                   const void *key, struct net_device *dev,
 348                                   int creat);
 349struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl, struct net *net,
 350                                     const void *key, struct net_device *dev);
 351int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
 352                  struct net_device *dev);
 353
 354static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
 355{
 356        return read_pnet(&pneigh->net);
 357}
 358
 359void neigh_app_ns(struct neighbour *n);
 360void neigh_for_each(struct neigh_table *tbl,
 361                    void (*cb)(struct neighbour *, void *), void *cookie);
 362void __neigh_for_each_release(struct neigh_table *tbl,
 363                              int (*cb)(struct neighbour *));
 364int neigh_xmit(int fam, struct net_device *, const void *, struct sk_buff *);
 365void pneigh_for_each(struct neigh_table *tbl,
 366                     void (*cb)(struct pneigh_entry *));
 367
 368struct neigh_seq_state {
 369        struct seq_net_private p;
 370        struct neigh_table *tbl;
 371        struct neigh_hash_table *nht;
 372        void *(*neigh_sub_iter)(struct neigh_seq_state *state,
 373                                struct neighbour *n, loff_t *pos);
 374        unsigned int bucket;
 375        unsigned int flags;
 376#define NEIGH_SEQ_NEIGH_ONLY    0x00000001
 377#define NEIGH_SEQ_IS_PNEIGH     0x00000002
 378#define NEIGH_SEQ_SKIP_NOARP    0x00000004
 379};
 380void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *,
 381                      unsigned int);
 382void *neigh_seq_next(struct seq_file *, void *, loff_t *);
 383void neigh_seq_stop(struct seq_file *, void *);
 384
 385int neigh_proc_dointvec(struct ctl_table *ctl, int write,
 386                        void __user *buffer, size_t *lenp, loff_t *ppos);
 387int neigh_proc_dointvec_jiffies(struct ctl_table *ctl, int write,
 388                                void __user *buffer,
 389                                size_t *lenp, loff_t *ppos);
 390int neigh_proc_dointvec_ms_jiffies(struct ctl_table *ctl, int write,
 391                                   void __user *buffer,
 392                                   size_t *lenp, loff_t *ppos);
 393
 394int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 395                          proc_handler *proc_handler);
 396void neigh_sysctl_unregister(struct neigh_parms *p);
 397
 398static inline void __neigh_parms_put(struct neigh_parms *parms)
 399{
 400        refcount_dec(&parms->refcnt);
 401}
 402
 403static inline struct neigh_parms *neigh_parms_clone(struct neigh_parms *parms)
 404{
 405        refcount_inc(&parms->refcnt);
 406        return parms;
 407}
 408
 409/*
 410 *      Neighbour references
 411 */
 412
 413static inline void neigh_release(struct neighbour *neigh)
 414{
 415        if (refcount_dec_and_test(&neigh->refcnt))
 416                neigh_destroy(neigh);
 417}
 418
 419static inline struct neighbour * neigh_clone(struct neighbour *neigh)
 420{
 421        if (neigh)
 422                refcount_inc(&neigh->refcnt);
 423        return neigh;
 424}
 425
 426#define neigh_hold(n)   refcount_inc(&(n)->refcnt)
 427
 428static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
 429{
 430        unsigned long now = jiffies;
 431        
 432        if (neigh->used != now)
 433                neigh->used = now;
 434        if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE)))
 435                return __neigh_event_send(neigh, skb);
 436        return 0;
 437}
 438
 439#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 440static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
 441{
 442        unsigned int seq, hh_alen;
 443
 444        do {
 445                seq = read_seqbegin(&hh->hh_lock);
 446                hh_alen = HH_DATA_ALIGN(ETH_HLEN);
 447                memcpy(skb->data - hh_alen, hh->hh_data, ETH_ALEN + hh_alen - ETH_HLEN);
 448        } while (read_seqretry(&hh->hh_lock, seq));
 449        return 0;
 450}
 451#endif
 452
 453static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
 454{
 455        unsigned int seq;
 456        unsigned int hh_len;
 457
 458        do {
 459                seq = read_seqbegin(&hh->hh_lock);
 460                hh_len = hh->hh_len;
 461                if (likely(hh_len <= HH_DATA_MOD)) {
 462                        /* this is inlined by gcc */
 463                        memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
 464                } else {
 465                        unsigned int hh_alen = HH_DATA_ALIGN(hh_len);
 466
 467                        memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
 468                }
 469        } while (read_seqretry(&hh->hh_lock, seq));
 470
 471        skb_push(skb, hh_len);
 472        return dev_queue_xmit(skb);
 473}
 474
 475static inline int neigh_output(struct neighbour *n, struct sk_buff *skb)
 476{
 477        const struct hh_cache *hh = &n->hh;
 478
 479        if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 480                return neigh_hh_output(hh, skb);
 481        else
 482                return n->output(n, skb);
 483}
 484
 485static inline struct neighbour *
 486__neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
 487{
 488        struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 489
 490        if (n || !creat)
 491                return n;
 492
 493        n = neigh_create(tbl, pkey, dev);
 494        return IS_ERR(n) ? NULL : n;
 495}
 496
 497static inline struct neighbour *
 498__neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
 499  struct net_device *dev)
 500{
 501        struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 502
 503        if (n)
 504                return n;
 505
 506        return neigh_create(tbl, pkey, dev);
 507}
 508
 509struct neighbour_cb {
 510        unsigned long sched_next;
 511        unsigned int flags;
 512};
 513
 514#define LOCALLY_ENQUEUED 0x1
 515
 516#define NEIGH_CB(skb)   ((struct neighbour_cb *)(skb)->cb)
 517
 518static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
 519                                     const struct net_device *dev)
 520{
 521        unsigned int seq;
 522
 523        do {
 524                seq = read_seqbegin(&n->ha_lock);
 525                memcpy(dst, n->ha, dev->addr_len);
 526        } while (read_seqretry(&n->ha_lock, seq));
 527}
 528
 529
 530#endif
 531