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         unsigned int            arp_queue_len_bytes;
 144         struct sk_buff_head     arp_queue;
 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         u8                      protocol;
 153         seqlock_t               ha_lock;
 154         unsigned char           ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))] __aligned(8);
 155         struct hh_cache         hh;
 156         int                     (*output)(struct neighbour *, struct sk_buff *);
 157         const struct neigh_ops  *ops;
 158         struct list_head        gc_list;
 159         struct rcu_head         rcu;
 160         struct net_device       *dev;
 161         u8                      primary_key[0];
 162 } __randomize_layout;
 163
 164 struct neigh_ops {
 165         int                     family;
 166         void                    (*solicit)(struct neighbour *, struct sk_buff *);
 167         void                    (*error_report)(struct neighbour *, struct sk_buff *);
 168         int                     (*output)(struct neighbour *, struct sk_buff *);
 169         int                     (*connected_output)(struct neighbour *, struct sk_buff *);
 170 };
 171
 172 struct pneigh_entry {
 173         struct pneigh_entry     *next;
 174         possible_net_t          net;
 175         struct net_device       *dev;
 176         u8                      flags;
 177         u8                      protocol;
 178         u8                      key[0];
 179 };
 180
 181 /*
 182  *      neighbour table manipulation
 183  */
 184
 185 #define NEIGH_NUM_HASH_RND      4
 186
 187 struct neigh_hash_table {
 188         struct neighbour __rcu  **hash_buckets;
 189         unsigned int            hash_shift;
 190         __u32                   hash_rnd[NEIGH_NUM_HASH_RND];
 191         struct rcu_head         rcu;
 192 };
 193
 194
 195 struct neigh_table {
 196         int                     family;
 197         unsigned int            entry_size;
 198         unsigned int            key_len;
 199         __be16                  protocol;
 200         __u32                   (*hash)(const void *pkey,
 201                                         const struct net_device *dev,
 202                                         __u32 *hash_rnd);
 203         bool                    (*key_eq)(const struct neighbour *, const void *pkey);
 204         int                     (*constructor)(struct neighbour *);
 205         int                     (*pconstructor)(struct pneigh_entry *);
 206         void                    (*pdestructor)(struct pneigh_entry *);
 207         void                    (*proxy_redo)(struct sk_buff *skb);
 208         bool                    (*allow_add)(const struct net_device *dev,
 209                                              struct netlink_ext_ack *extack);
 210         char                    *id;
 211         struct neigh_parms      parms;
 212         struct list_head        parms_list;
 213         int                     gc_interval;
 214         int                     gc_thresh1;
 215         int                     gc_thresh2;
 216         int                     gc_thresh3;
 217         unsigned long           last_flush;
 218         struct delayed_work     gc_work;
 219         struct timer_list       proxy_timer;
 220         struct sk_buff_head     proxy_queue;
 221         atomic_t                entries;
 222         atomic_t                gc_entries;
 223         struct list_head        gc_list;
 224         rwlock_t                lock;
 225         unsigned long           last_rand;
 226         struct neigh_statistics __percpu *stats;
 227         struct neigh_hash_table __rcu *nht;
 228         struct pneigh_entry     **phash_buckets;
 229 };
 230
 231 enum {
 232         NEIGH_ARP_TABLE = 0,
 233         NEIGH_ND_TABLE = 1,
 234         NEIGH_DN_TABLE = 2,
 235         NEIGH_NR_TABLES,
 236         NEIGH_LINK_TABLE = NEIGH_NR_TABLES /* Pseudo table for neigh_xmit */
 237 };
 238
 239 static inline int neigh_parms_family(struct neigh_parms *p)
 240 {
 241         return p->tbl->family;
 242 }
 243
 244 #define NEIGH_PRIV_ALIGN        sizeof(long long)
 245 #define NEIGH_ENTRY_SIZE(size)  ALIGN((size), NEIGH_PRIV_ALIGN)
 246
 247 static inline void *neighbour_priv(const struct neighbour *n)
 248 {
 249         return (char *)n + n->tbl->entry_size;
 250 }
 251
 252 /* flags for neigh_update() */
 253 #define NEIGH_UPDATE_F_OVERRIDE                 0x00000001
 254 #define NEIGH_UPDATE_F_WEAK_OVERRIDE            0x00000002
 255 #define NEIGH_UPDATE_F_OVERRIDE_ISROUTER        0x00000004
 256 #define NEIGH_UPDATE_F_EXT_LEARNED              0x20000000
 257 #define NEIGH_UPDATE_F_ISROUTER                 0x40000000
 258 #define NEIGH_UPDATE_F_ADMIN                    0x80000000
 259
 260 extern const struct nla_policy nda_policy[];
 261
 262 static inline bool neigh_key_eq16(const struct neighbour *n, const void *pkey)
 263 {
 264         return *(const u16 *)n->primary_key == *(const u16 *)pkey;
 265 }
 266
 267 static inline bool neigh_key_eq32(const struct neighbour *n, const void *pkey)
 268 {
 269         return *(const u32 *)n->primary_key == *(const u32 *)pkey;
 270 }
 271
 272 static inline bool neigh_key_eq128(const struct neighbour *n, const void *pkey)
 273 {
 274         const u32 *n32 = (const u32 *)n->primary_key;
 275         const u32 *p32 = pkey;
 276
 277         return ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
 278                 (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0;
 279 }
 280
 281 static inline struct neighbour *___neigh_lookup_noref(
 282         struct neigh_table *tbl,
 283         bool (*key_eq)(const struct neighbour *n, const void *pkey),
 284         __u32 (*hash)(const void *pkey,
 285                       const struct net_device *dev,
 286                       __u32 *hash_rnd),
 287         const void *pkey,
 288         struct net_device *dev)
 289 {
 290         struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht);
 291         struct neighbour *n;
 292         u32 hash_val;
 293
 294         hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
 295         for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
 296              n != NULL;
 297              n = rcu_dereference_bh(n->next)) {
 298                 if (n->dev == dev && key_eq(n, pkey))
 299                         return n;
 300         }
 301
 302         return NULL;
 303 }
 304
 305 static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl,
 306                                                      const void *pkey,
 307                                                      struct net_device *dev)
 308 {
 309         return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev);
 310 }
 311
 312 void neigh_table_init(int index, struct neigh_table *tbl);
 313 int neigh_table_clear(int index, struct neigh_table *tbl);
 314 struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
 315                                struct net_device *dev);
 316 struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
 317                                      const void *pkey);
 318 struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
 319                                  struct net_device *dev, bool want_ref);
 320 static inline struct neighbour *neigh_create(struct neigh_table *tbl,
 321                                              const void *pkey,
 322                                              struct net_device *dev)
 323 {
 324         return __neigh_create(tbl, pkey, dev, true);
 325 }
 326 void neigh_destroy(struct neighbour *neigh);
 327 int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
 328 int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags,
 329                  u32 nlmsg_pid);
 330 void __neigh_set_probe_once(struct neighbour *neigh);
 331 bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl);
 332 void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
 333 int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 334 int neigh_carrier_down(struct neigh_table *tbl, struct net_device *dev);
 335 int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
 336 int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
 337 int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
 338 struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 339                                                 u8 *lladdr, void *saddr,
 340                                                 struct net_device *dev);
 341
 342 struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 343                                       struct neigh_table *tbl);
 344 void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);
 345
 346 static inline
 347 struct net *neigh_parms_net(const struct neigh_parms *parms)
 348 {
 349         return read_pnet(&parms->net);
 350 }
 351
 352 unsigned long neigh_rand_reach_time(unsigned long base);
 353
 354 void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 355                     struct sk_buff *skb);
 356 struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
 357                                    const void *key, struct net_device *dev,
 358                                    int creat);
 359 struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl, struct net *net,
 360                                      const void *key, struct net_device *dev);
 361 int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
 362                   struct net_device *dev);
 363
 364 static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
 365 {
 366         return read_pnet(&pneigh->net);
 367 }
 368
 369 void neigh_app_ns(struct neighbour *n);
 370 void neigh_for_each(struct neigh_table *tbl,
 371                     void (*cb)(struct neighbour *, void *), void *cookie);
 372 void __neigh_for_each_release(struct neigh_table *tbl,
 373                               int (*cb)(struct neighbour *));
 374 int neigh_xmit(int fam, struct net_device *, const void *, struct sk_buff *);
 375 void pneigh_for_each(struct neigh_table *tbl,
 376                      void (*cb)(struct pneigh_entry *));
 377
 378 struct neigh_seq_state {
 379         struct seq_net_private p;
 380         struct neigh_table *tbl;
 381         struct neigh_hash_table *nht;
 382         void *(*neigh_sub_iter)(struct neigh_seq_state *state,
 383                                 struct neighbour *n, loff_t *pos);
 384         unsigned int bucket;
 385         unsigned int flags;
 386 #define NEIGH_SEQ_NEIGH_ONLY    0x00000001
 387 #define NEIGH_SEQ_IS_PNEIGH     0x00000002
 388 #define NEIGH_SEQ_SKIP_NOARP    0x00000004
 389 };
 390 void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *,
 391                       unsigned int);
 392 void *neigh_seq_next(struct seq_file *, void *, loff_t *);
 393 void neigh_seq_stop(struct seq_file *, void *);
 394
 395 int neigh_proc_dointvec(struct ctl_table *ctl, int write,
 396                         void __user *buffer, size_t *lenp, loff_t *ppos);
 397 int neigh_proc_dointvec_jiffies(struct ctl_table *ctl, int write,
 398                                 void __user *buffer,
 399                                 size_t *lenp, loff_t *ppos);
 400 int neigh_proc_dointvec_ms_jiffies(struct ctl_table *ctl, int write,
 401                                    void __user *buffer,
 402                                    size_t *lenp, loff_t *ppos);
 403
 404 int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 405                           proc_handler *proc_handler);
 406 void neigh_sysctl_unregister(struct neigh_parms *p);
 407
 408 static inline void __neigh_parms_put(struct neigh_parms *parms)
 409 {
 410         refcount_dec(&parms->refcnt);
 411 }
 412
 413 static inline struct neigh_parms *neigh_parms_clone(struct neigh_parms *parms)
 414 {
 415         refcount_inc(&parms->refcnt);
 416         return parms;
 417 }
 418
 419 /*
 420  *      Neighbour references
 421  */
 422
 423 static inline void neigh_release(struct neighbour *neigh)
 424 {
 425         if (refcount_dec_and_test(&neigh->refcnt))
 426                 neigh_destroy(neigh);
 427 }
 428
 429 static inline struct neighbour * neigh_clone(struct neighbour *neigh)
 430 {
 431         if (neigh)
 432                 refcount_inc(&neigh->refcnt);
 433         return neigh;
 434 }
 435
 436 #define neigh_hold(n)   refcount_inc(&(n)->refcnt)
 437
 438 static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
 439 {
 440         unsigned long now = jiffies;
 441
 442         if (neigh->used != now)
 443                 neigh->used = now;
 444         if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE)))
 445                 return __neigh_event_send(neigh, skb);
 446         return 0;
 447 }
 448
 449 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 450 static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
 451 {
 452         unsigned int seq, hh_alen;
 453
 454         do {
 455                 seq = read_seqbegin(&hh->hh_lock);
 456                 hh_alen = HH_DATA_ALIGN(ETH_HLEN);
 457                 memcpy(skb->data - hh_alen, hh->hh_data, ETH_ALEN + hh_alen - ETH_HLEN);
 458         } while (read_seqretry(&hh->hh_lock, seq));
 459         return 0;
 460 }
 461 #endif
 462
 463 static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
 464 {
 465         unsigned int hh_alen = 0;
 466         unsigned int seq;
 467         unsigned int hh_len;
 468
 469         do {
 470                 seq = read_seqbegin(&hh->hh_lock);
 471                 hh_len = hh->hh_len;
 472                 if (likely(hh_len <= HH_DATA_MOD)) {
 473                         hh_alen = HH_DATA_MOD;
 474
 475                         /* skb_push() would proceed silently if we have room for
 476                          * the unaligned size but not for the aligned size:
 477                          * check headroom explicitly.
 478                          */
 479                         if (likely(skb_headroom(skb) >= HH_DATA_MOD)) {
 480                                 /* this is inlined by gcc */
 481                                 memcpy(skb->data - HH_DATA_MOD, hh->hh_data,
 482                                        HH_DATA_MOD);
 483                         }
 484                 } else {
 485                         hh_alen = HH_DATA_ALIGN(hh_len);
 486
 487                         if (likely(skb_headroom(skb) >= hh_alen)) {
 488                                 memcpy(skb->data - hh_alen, hh->hh_data,
 489                                        hh_alen);
 490                         }
 491                 }
 492         } while (read_seqretry(&hh->hh_lock, seq));
 493
 494         if (WARN_ON_ONCE(skb_headroom(skb) < hh_alen)) {
 495                 kfree_skb(skb);
 496                 return NET_XMIT_DROP;
 497         }
 498
 499         __skb_push(skb, hh_len);
 500         return dev_queue_xmit(skb);
 501 }
 502
 503 static inline int neigh_output(struct neighbour *n, struct sk_buff *skb,
 504                                bool skip_cache)
 505 {
 506         const struct hh_cache *hh = &n->hh;
 507
 508         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len && !skip_cache)
 509                 return neigh_hh_output(hh, skb);
 510         else
 511                 return n->output(n, skb);
 512 }
 513
 514 static inline struct neighbour *
 515 __neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
 516 {
 517         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 518
 519         if (n || !creat)
 520                 return n;
 521
 522         n = neigh_create(tbl, pkey, dev);
 523         return IS_ERR(n) ? NULL : n;
 524 }
 525
 526 static inline struct neighbour *
 527 __neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
 528   struct net_device *dev)
 529 {
 530         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 531
 532         if (n)
 533                 return n;
 534
 535         return neigh_create(tbl, pkey, dev);
 536 }
 537
 538 struct neighbour_cb {
 539         unsigned long sched_next;
 540         unsigned int flags;
 541 };
 542
 543 #define LOCALLY_ENQUEUED 0x1
 544
 545 #define NEIGH_CB(skb)   ((struct neighbour_cb *)(skb)->cb)
 546
 547 static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
 548                                      const struct net_device *dev)
 549 {
 550         unsigned int seq;
 551
 552         do {
 553                 seq = read_seqbegin(&n->ha_lock);
 554                 memcpy(dst, n->ha, dev->addr_len);
 555         } while (read_seqretry(&n->ha_lock, seq));
 556 }
 557
 558 static inline void neigh_update_is_router(struct neighbour *neigh, u32 flags,
 559                                           int *notify)
 560 {
 561         u8 ndm_flags = 0;
 562
 563         ndm_flags |= (flags & NEIGH_UPDATE_F_ISROUTER) ? NTF_ROUTER : 0;
 564         if ((neigh->flags ^ ndm_flags) & NTF_ROUTER) {
 565                 if (ndm_flags & NTF_ROUTER)
 566                         neigh->flags |= NTF_ROUTER;
 567                 else
 568                         neigh->flags &= ~NTF_ROUTER;
 569                 *notify = 1;
 570         }
 571 }
 572 #endif