include/net/neighbour.h

   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
  41 struct neighbour;
  42
  43 enum {
  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
  70 struct 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
  89 static 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
 103 static inline void neigh_parms_data_state_setall(struct neigh_parms *p)
 104 {
 105         bitmap_fill(p->data_state, NEIGH_VAR_DATA_MAX);
 106 }
 107
 108 static inline void neigh_parms_data_state_cleanall(struct neigh_parms *p)
 109 {
 110         bitmap_zero(p->data_state, NEIGH_VAR_DATA_MAX);
 111 }
 112
 113 struct 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
 135 struct 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
 162 struct 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
 170 struct 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
 184 struct 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
 192 struct 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
 224 enum {
 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
 232 static 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
 240 static 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
 253 static 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
 258 static 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
 263 static 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
 272 static 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
 296 static 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
 303 void neigh_table_init(int index, struct neigh_table *tbl);
 304 int neigh_table_clear(int index, struct neigh_table *tbl);
 305 struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
 306                                struct net_device *dev);
 307 struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
 308                                      const void *pkey);
 309 struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
 310                                  struct net_device *dev, bool want_ref);
 311 static 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 }
 317 void neigh_destroy(struct neighbour *neigh);
 318 int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
 319 int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags,
 320                  u32 nlmsg_pid);
 321 void __neigh_set_probe_once(struct neighbour *neigh);
 322 bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl);
 323 void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
 324 int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 325 int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
 326 int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
 327 int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
 328 struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 329                                                 u8 *lladdr, void *saddr,
 330                                                 struct net_device *dev);
 331
 332 struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 333                                       struct neigh_table *tbl);
 334 void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);
 335
 336 static inline
 337 struct net *neigh_parms_net(const struct neigh_parms *parms)
 338 {
 339         return read_pnet(&parms->net);
 340 }
 341
 342 unsigned long neigh_rand_reach_time(unsigned long base);
 343
 344 void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 345                     struct sk_buff *skb);
 346 struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
 347                                    const void *key, struct net_device *dev,
 348                                    int creat);
 349 struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl, struct net *net,
 350                                      const void *key, struct net_device *dev);
 351 int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
 352                   struct net_device *dev);
 353
 354 static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
 355 {
 356         return read_pnet(&pneigh->net);
 357 }
 358
 359 void neigh_app_ns(struct neighbour *n);
 360 void neigh_for_each(struct neigh_table *tbl,
 361                     void (*cb)(struct neighbour *, void *), void *cookie);
 362 void __neigh_for_each_release(struct neigh_table *tbl,
 363                               int (*cb)(struct neighbour *));
 364 int neigh_xmit(int fam, struct net_device *, const void *, struct sk_buff *);
 365 void pneigh_for_each(struct neigh_table *tbl,
 366                      void (*cb)(struct pneigh_entry *));
 367
 368 struct 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 };
 380 void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *,
 381                       unsigned int);
 382 void *neigh_seq_next(struct seq_file *, void *, loff_t *);
 383 void neigh_seq_stop(struct seq_file *, void *);
 384
 385 int neigh_proc_dointvec(struct ctl_table *ctl, int write,
 386                         void __user *buffer, size_t *lenp, loff_t *ppos);
 387 int neigh_proc_dointvec_jiffies(struct ctl_table *ctl, int write,
 388                                 void __user *buffer,
 389                                 size_t *lenp, loff_t *ppos);
 390 int neigh_proc_dointvec_ms_jiffies(struct ctl_table *ctl, int write,
 391                                    void __user *buffer,
 392                                    size_t *lenp, loff_t *ppos);
 393
 394 int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 395                           proc_handler *proc_handler);
 396 void neigh_sysctl_unregister(struct neigh_parms *p);
 397
 398 static inline void __neigh_parms_put(struct neigh_parms *parms)
 399 {
 400         refcount_dec(&parms->refcnt);
 401 }
 402
 403 static 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
 413 static inline void neigh_release(struct neighbour *neigh)
 414 {
 415         if (refcount_dec_and_test(&neigh->refcnt))
 416                 neigh_destroy(neigh);
 417 }
 418
 419 static 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
 428 static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
 429 {
 430         unsigned long now = jiffies;
 431
 432         if (READ_ONCE(neigh->used) != now)
 433                 WRITE_ONCE(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)
 440 static 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
 453 static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
 454 {
 455         unsigned int hh_alen = 0;
 456         unsigned int seq;
 457         unsigned int hh_len;
 458
 459         do {
 460                 seq = read_seqbegin(&hh->hh_lock);
 461                 hh_len = READ_ONCE(hh->hh_len);
 462                 if (likely(hh_len <= HH_DATA_MOD)) {
 463                         hh_alen = HH_DATA_MOD;
 464
 465                         /* skb_push() would proceed silently if we have room for
 466                          * the unaligned size but not for the aligned size:
 467                          * check headroom explicitly.
 468                          */
 469                         if (likely(skb_headroom(skb) >= HH_DATA_MOD)) {
 470                                 /* this is inlined by gcc */
 471                                 memcpy(skb->data - HH_DATA_MOD, hh->hh_data,
 472                                        HH_DATA_MOD);
 473                         }
 474                 } else {
 475                         hh_alen = HH_DATA_ALIGN(hh_len);
 476
 477                         if (likely(skb_headroom(skb) >= hh_alen)) {
 478                                 memcpy(skb->data - hh_alen, hh->hh_data,
 479                                        hh_alen);
 480                         }
 481                 }
 482         } while (read_seqretry(&hh->hh_lock, seq));
 483
 484         if (WARN_ON_ONCE(skb_headroom(skb) < hh_alen)) {
 485                 kfree_skb(skb);
 486                 return NET_XMIT_DROP;
 487         }
 488
 489         __skb_push(skb, hh_len);
 490         return dev_queue_xmit(skb);
 491 }
 492
 493 static inline int neigh_output(struct neighbour *n, struct sk_buff *skb)
 494 {
 495         const struct hh_cache *hh = &n->hh;
 496
 497         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 498                 return neigh_hh_output(hh, skb);
 499         else
 500                 return n->output(n, skb);
 501 }
 502
 503 static inline struct neighbour *
 504 __neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
 505 {
 506         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 507
 508         if (n || !creat)
 509                 return n;
 510
 511         n = neigh_create(tbl, pkey, dev);
 512         return IS_ERR(n) ? NULL : n;
 513 }
 514
 515 static inline struct neighbour *
 516 __neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
 517   struct net_device *dev)
 518 {
 519         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 520
 521         if (n)
 522                 return n;
 523
 524         return neigh_create(tbl, pkey, dev);
 525 }
 526
 527 struct neighbour_cb {
 528         unsigned long sched_next;
 529         unsigned int flags;
 530 };
 531
 532 #define LOCALLY_ENQUEUED 0x1
 533
 534 #define NEIGH_CB(skb)   ((struct neighbour_cb *)(skb)->cb)
 535
 536 static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
 537                                      const struct net_device *dev)
 538 {
 539         unsigned int seq;
 540
 541         do {
 542                 seq = read_seqbegin(&n->ha_lock);
 543                 memcpy(dst, n->ha, dev->addr_len);
 544         } while (read_seqretry(&n->ha_lock, seq));
 545 }
 546
 547
 548 #endif