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         struct neigh_table *tbl;
  76
  77         void    *sysctl_table;
  78
  79         int dead;
  80         refcount_t refcnt;
  81         struct rcu_head rcu_head;
  82
  83         int     reachable_time;
  84         int     data[NEIGH_VAR_DATA_MAX];
  85         DECLARE_BITMAP(data_state, NEIGH_VAR_DATA_MAX);
  86 };
  87
  88 static inline void neigh_var_set(struct neigh_parms *p, int index, int val)
  89 {
  90         set_bit(index, p->data_state);
  91         p->data[index] = val;
  92 }
  93
  94 #define NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr])
  95
  96 /* In ndo_neigh_setup, NEIGH_VAR_INIT should be used.
  97  * In other cases, NEIGH_VAR_SET should be used.
  98  */
  99 #define NEIGH_VAR_INIT(p, attr, val) (NEIGH_VAR(p, attr) = val)
 100 #define NEIGH_VAR_SET(p, attr, val) neigh_var_set(p, NEIGH_VAR_ ## attr, val)
 101
 102 static inline void neigh_parms_data_state_setall(struct neigh_parms *p)
 103 {
 104         bitmap_fill(p->data_state, NEIGH_VAR_DATA_MAX);
 105 }
 106
 107 static inline void neigh_parms_data_state_cleanall(struct neigh_parms *p)
 108 {
 109         bitmap_zero(p->data_state, NEIGH_VAR_DATA_MAX);
 110 }
 111
 112 struct neigh_statistics {
 113         unsigned long allocs;           /* number of allocated neighs */
 114         unsigned long destroys;         /* number of destroyed neighs */
 115         unsigned long hash_grows;       /* number of hash resizes */
 116
 117         unsigned long res_failed;       /* number of failed resolutions */
 118
 119         unsigned long lookups;          /* number of lookups */
 120         unsigned long hits;             /* number of hits (among lookups) */
 121
 122         unsigned long rcv_probes_mcast; /* number of received mcast ipv6 */
 123         unsigned long rcv_probes_ucast; /* number of received ucast ipv6 */
 124
 125         unsigned long periodic_gc_runs; /* number of periodic GC runs */
 126         unsigned long forced_gc_runs;   /* number of forced GC runs */
 127
 128         unsigned long unres_discards;   /* number of unresolved drops */
 129         unsigned long table_fulls;      /* times even gc couldn't help */
 130 };
 131
 132 #define NEIGH_CACHE_STAT_INC(tbl, field) this_cpu_inc((tbl)->stats->field)
 133
 134 struct neighbour {
 135         struct neighbour __rcu  *next;
 136         struct neigh_table      *tbl;
 137         struct neigh_parms      *parms;
 138         unsigned long           confirmed;
 139         unsigned long           updated;
 140         rwlock_t                lock;
 141         refcount_t              refcnt;
 142         unsigned int            arp_queue_len_bytes;
 143         struct sk_buff_head     arp_queue;
 144         struct timer_list       timer;
 145         unsigned long           used;
 146         atomic_t                probes;
 147         __u8                    flags;
 148         __u8                    nud_state;
 149         __u8                    type;
 150         __u8                    dead;
 151         u8                      protocol;
 152         seqlock_t               ha_lock;
 153         unsigned char           ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))] __aligned(8);
 154         struct hh_cache         hh;
 155         int                     (*output)(struct neighbour *, struct sk_buff *);
 156         const struct neigh_ops  *ops;
 157         struct list_head        gc_list;
 158         struct rcu_head         rcu;
 159         struct net_device       *dev;
 160         u8                      primary_key[0];
 161 } __randomize_layout;
 162
 163 struct neigh_ops {
 164         int                     family;
 165         void                    (*solicit)(struct neighbour *, struct sk_buff *);
 166         void                    (*error_report)(struct neighbour *, struct sk_buff *);
 167         int                     (*output)(struct neighbour *, struct sk_buff *);
 168         int                     (*connected_output)(struct neighbour *, struct sk_buff *);
 169 };
 170
 171 struct pneigh_entry {
 172         struct pneigh_entry     *next;
 173         possible_net_t          net;
 174         struct net_device       *dev;
 175         u8                      flags;
 176         u8                      protocol;
 177         u8                      key[];
 178 };
 179
 180 /*
 181  *      neighbour table manipulation
 182  */
 183
 184 #define NEIGH_NUM_HASH_RND      4
 185
 186 struct neigh_hash_table {
 187         struct neighbour __rcu  **hash_buckets;
 188         unsigned int            hash_shift;
 189         __u32                   hash_rnd[NEIGH_NUM_HASH_RND];
 190         struct rcu_head         rcu;
 191 };
 192
 193
 194 struct neigh_table {
 195         int                     family;
 196         unsigned int            entry_size;
 197         unsigned int            key_len;
 198         __be16                  protocol;
 199         __u32                   (*hash)(const void *pkey,
 200                                         const struct net_device *dev,
 201                                         __u32 *hash_rnd);
 202         bool                    (*key_eq)(const struct neighbour *, const void *pkey);
 203         int                     (*constructor)(struct neighbour *);
 204         int                     (*pconstructor)(struct pneigh_entry *);
 205         void                    (*pdestructor)(struct pneigh_entry *);
 206         void                    (*proxy_redo)(struct sk_buff *skb);
 207         bool                    (*allow_add)(const struct net_device *dev,
 208                                              struct netlink_ext_ack *extack);
 209         char                    *id;
 210         struct neigh_parms      parms;
 211         struct list_head        parms_list;
 212         int                     gc_interval;
 213         int                     gc_thresh1;
 214         int                     gc_thresh2;
 215         int                     gc_thresh3;
 216         unsigned long           last_flush;
 217         struct delayed_work     gc_work;
 218         struct timer_list       proxy_timer;
 219         struct sk_buff_head     proxy_queue;
 220         atomic_t                entries;
 221         atomic_t                gc_entries;
 222         struct list_head        gc_list;
 223         rwlock_t                lock;
 224         unsigned long           last_rand;
 225         struct neigh_statistics __percpu *stats;
 226         struct neigh_hash_table __rcu *nht;
 227         struct pneigh_entry     **phash_buckets;
 228 };
 229
 230 enum {
 231         NEIGH_ARP_TABLE = 0,
 232         NEIGH_ND_TABLE = 1,
 233         NEIGH_DN_TABLE = 2,
 234         NEIGH_NR_TABLES,
 235         NEIGH_LINK_TABLE = NEIGH_NR_TABLES /* Pseudo table for neigh_xmit */
 236 };
 237
 238 static inline int neigh_parms_family(struct neigh_parms *p)
 239 {
 240         return p->tbl->family;
 241 }
 242
 243 #define NEIGH_PRIV_ALIGN        sizeof(long long)
 244 #define NEIGH_ENTRY_SIZE(size)  ALIGN((size), NEIGH_PRIV_ALIGN)
 245
 246 static inline void *neighbour_priv(const struct neighbour *n)
 247 {
 248         return (char *)n + n->tbl->entry_size;
 249 }
 250
 251 /* flags for neigh_update() */
 252 #define NEIGH_UPDATE_F_OVERRIDE                 0x00000001
 253 #define NEIGH_UPDATE_F_WEAK_OVERRIDE            0x00000002
 254 #define NEIGH_UPDATE_F_OVERRIDE_ISROUTER        0x00000004
 255 #define NEIGH_UPDATE_F_EXT_LEARNED              0x20000000
 256 #define NEIGH_UPDATE_F_ISROUTER                 0x40000000
 257 #define NEIGH_UPDATE_F_ADMIN                    0x80000000
 258
 259 extern const struct nla_policy nda_policy[];
 260
 261 static inline bool neigh_key_eq16(const struct neighbour *n, const void *pkey)
 262 {
 263         return *(const u16 *)n->primary_key == *(const u16 *)pkey;
 264 }
 265
 266 static inline bool neigh_key_eq32(const struct neighbour *n, const void *pkey)
 267 {
 268         return *(const u32 *)n->primary_key == *(const u32 *)pkey;
 269 }
 270
 271 static inline bool neigh_key_eq128(const struct neighbour *n, const void *pkey)
 272 {
 273         const u32 *n32 = (const u32 *)n->primary_key;
 274         const u32 *p32 = pkey;
 275
 276         return ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
 277                 (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0;
 278 }
 279
 280 static inline struct neighbour *___neigh_lookup_noref(
 281         struct neigh_table *tbl,
 282         bool (*key_eq)(const struct neighbour *n, const void *pkey),
 283         __u32 (*hash)(const void *pkey,
 284                       const struct net_device *dev,
 285                       __u32 *hash_rnd),
 286         const void *pkey,
 287         struct net_device *dev)
 288 {
 289         struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht);
 290         struct neighbour *n;
 291         u32 hash_val;
 292
 293         hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
 294         for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
 295              n != NULL;
 296              n = rcu_dereference_bh(n->next)) {
 297                 if (n->dev == dev && key_eq(n, pkey))
 298                         return n;
 299         }
 300
 301         return NULL;
 302 }
 303
 304 static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl,
 305                                                      const void *pkey,
 306                                                      struct net_device *dev)
 307 {
 308         return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev);
 309 }
 310
 311 void neigh_table_init(int index, struct neigh_table *tbl);
 312 int neigh_table_clear(int index, struct neigh_table *tbl);
 313 struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
 314                                struct net_device *dev);
 315 struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
 316                                      const void *pkey);
 317 struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
 318                                  struct net_device *dev, bool want_ref);
 319 static inline struct neighbour *neigh_create(struct neigh_table *tbl,
 320                                              const void *pkey,
 321                                              struct net_device *dev)
 322 {
 323         return __neigh_create(tbl, pkey, dev, true);
 324 }
 325 void neigh_destroy(struct neighbour *neigh);
 326 int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
 327 int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags,
 328                  u32 nlmsg_pid);
 329 void __neigh_set_probe_once(struct neighbour *neigh);
 330 bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl);
 331 void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
 332 int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 333 int neigh_carrier_down(struct neigh_table *tbl, struct net_device *dev);
 334 int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
 335 int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
 336 int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
 337 struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 338                                                 u8 *lladdr, void *saddr,
 339                                                 struct net_device *dev);
 340
 341 struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 342                                       struct neigh_table *tbl);
 343 void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);
 344
 345 static inline
 346 struct net *neigh_parms_net(const struct neigh_parms *parms)
 347 {
 348         return read_pnet(&parms->net);
 349 }
 350
 351 unsigned long neigh_rand_reach_time(unsigned long base);
 352
 353 void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
 354                     struct sk_buff *skb);
 355 struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
 356                                    const void *key, struct net_device *dev,
 357                                    int creat);
 358 struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl, struct net *net,
 359                                      const void *key, struct net_device *dev);
 360 int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
 361                   struct net_device *dev);
 362
 363 static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
 364 {
 365         return read_pnet(&pneigh->net);
 366 }
 367
 368 void neigh_app_ns(struct neighbour *n);
 369 void neigh_for_each(struct neigh_table *tbl,
 370                     void (*cb)(struct neighbour *, void *), void *cookie);
 371 void __neigh_for_each_release(struct neigh_table *tbl,
 372                               int (*cb)(struct neighbour *));
 373 int neigh_xmit(int fam, struct net_device *, const void *, struct sk_buff *);
 374 void pneigh_for_each(struct neigh_table *tbl,
 375                      void (*cb)(struct pneigh_entry *));
 376
 377 struct neigh_seq_state {
 378         struct seq_net_private p;
 379         struct neigh_table *tbl;
 380         struct neigh_hash_table *nht;
 381         void *(*neigh_sub_iter)(struct neigh_seq_state *state,
 382                                 struct neighbour *n, loff_t *pos);
 383         unsigned int bucket;
 384         unsigned int flags;
 385 #define NEIGH_SEQ_NEIGH_ONLY    0x00000001
 386 #define NEIGH_SEQ_IS_PNEIGH     0x00000002
 387 #define NEIGH_SEQ_SKIP_NOARP    0x00000004
 388 };
 389 void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *,
 390                       unsigned int);
 391 void *neigh_seq_next(struct seq_file *, void *, loff_t *);
 392 void neigh_seq_stop(struct seq_file *, void *);
 393
 394 int neigh_proc_dointvec(struct ctl_table *ctl, int write,
 395                         void __user *buffer, size_t *lenp, loff_t *ppos);
 396 int neigh_proc_dointvec_jiffies(struct ctl_table *ctl, int write,
 397                                 void __user *buffer,
 398                                 size_t *lenp, loff_t *ppos);
 399 int neigh_proc_dointvec_ms_jiffies(struct ctl_table *ctl, int write,
 400                                    void __user *buffer,
 401                                    size_t *lenp, loff_t *ppos);
 402
 403 int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 404                           proc_handler *proc_handler);
 405 void neigh_sysctl_unregister(struct neigh_parms *p);
 406
 407 static inline void __neigh_parms_put(struct neigh_parms *parms)
 408 {
 409         refcount_dec(&parms->refcnt);
 410 }
 411
 412 static inline struct neigh_parms *neigh_parms_clone(struct neigh_parms *parms)
 413 {
 414         refcount_inc(&parms->refcnt);
 415         return parms;
 416 }
 417
 418 /*
 419  *      Neighbour references
 420  */
 421
 422 static inline void neigh_release(struct neighbour *neigh)
 423 {
 424         if (refcount_dec_and_test(&neigh->refcnt))
 425                 neigh_destroy(neigh);
 426 }
 427
 428 static inline struct neighbour * neigh_clone(struct neighbour *neigh)
 429 {
 430         if (neigh)
 431                 refcount_inc(&neigh->refcnt);
 432         return neigh;
 433 }
 434
 435 #define neigh_hold(n)   refcount_inc(&(n)->refcnt)
 436
 437 static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
 438 {
 439         unsigned long now = jiffies;
 440
 441         if (READ_ONCE(neigh->used) != now)
 442                 WRITE_ONCE(neigh->used, now);
 443         if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE)))
 444                 return __neigh_event_send(neigh, skb);
 445         return 0;
 446 }
 447
 448 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 449 static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
 450 {
 451         unsigned int seq, hh_alen;
 452
 453         do {
 454                 seq = read_seqbegin(&hh->hh_lock);
 455                 hh_alen = HH_DATA_ALIGN(ETH_HLEN);
 456                 memcpy(skb->data - hh_alen, hh->hh_data, ETH_ALEN + hh_alen - ETH_HLEN);
 457         } while (read_seqretry(&hh->hh_lock, seq));
 458         return 0;
 459 }
 460 #endif
 461
 462 static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
 463 {
 464         unsigned int hh_alen = 0;
 465         unsigned int seq;
 466         unsigned int hh_len;
 467
 468         do {
 469                 seq = read_seqbegin(&hh->hh_lock);
 470                 hh_len = READ_ONCE(hh->hh_len);
 471                 if (likely(hh_len <= HH_DATA_MOD)) {
 472                         hh_alen = HH_DATA_MOD;
 473
 474                         /* skb_push() would proceed silently if we have room for
 475                          * the unaligned size but not for the aligned size:
 476                          * check headroom explicitly.
 477                          */
 478                         if (likely(skb_headroom(skb) >= HH_DATA_MOD)) {
 479                                 /* this is inlined by gcc */
 480                                 memcpy(skb->data - HH_DATA_MOD, hh->hh_data,
 481                                        HH_DATA_MOD);
 482                         }
 483                 } else {
 484                         hh_alen = HH_DATA_ALIGN(hh_len);
 485
 486                         if (likely(skb_headroom(skb) >= hh_alen)) {
 487                                 memcpy(skb->data - hh_alen, hh->hh_data,
 488                                        hh_alen);
 489                         }
 490                 }
 491         } while (read_seqretry(&hh->hh_lock, seq));
 492
 493         if (WARN_ON_ONCE(skb_headroom(skb) < hh_alen)) {
 494                 kfree_skb(skb);
 495                 return NET_XMIT_DROP;
 496         }
 497
 498         __skb_push(skb, hh_len);
 499         return dev_queue_xmit(skb);
 500 }
 501
 502 static inline int neigh_output(struct neighbour *n, struct sk_buff *skb,
 503                                bool skip_cache)
 504 {
 505         const struct hh_cache *hh = &n->hh;
 506
 507         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len && !skip_cache)
 508                 return neigh_hh_output(hh, skb);
 509         else
 510                 return n->output(n, skb);
 511 }
 512
 513 static inline struct neighbour *
 514 __neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
 515 {
 516         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 517
 518         if (n || !creat)
 519                 return n;
 520
 521         n = neigh_create(tbl, pkey, dev);
 522         return IS_ERR(n) ? NULL : n;
 523 }
 524
 525 static inline struct neighbour *
 526 __neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
 527   struct net_device *dev)
 528 {
 529         struct neighbour *n = neigh_lookup(tbl, pkey, dev);
 530
 531         if (n)
 532                 return n;
 533
 534         return neigh_create(tbl, pkey, dev);
 535 }
 536
 537 struct neighbour_cb {
 538         unsigned long sched_next;
 539         unsigned int flags;
 540 };
 541
 542 #define LOCALLY_ENQUEUED 0x1
 543
 544 #define NEIGH_CB(skb)   ((struct neighbour_cb *)(skb)->cb)
 545
 546 static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
 547                                      const struct net_device *dev)
 548 {
 549         unsigned int seq;
 550
 551         do {
 552                 seq = read_seqbegin(&n->ha_lock);
 553                 memcpy(dst, n->ha, dev->addr_len);
 554         } while (read_seqretry(&n->ha_lock, seq));
 555 }
 556
 557 static inline void neigh_update_is_router(struct neighbour *neigh, u32 flags,
 558                                           int *notify)
 559 {
 560         u8 ndm_flags = 0;
 561
 562         ndm_flags |= (flags & NEIGH_UPDATE_F_ISROUTER) ? NTF_ROUTER : 0;
 563         if ((neigh->flags ^ ndm_flags) & NTF_ROUTER) {
 564                 if (ndm_flags & NTF_ROUTER)
 565                         neigh->flags |= NTF_ROUTER;
 566                 else
 567                         neigh->flags &= ~NTF_ROUTER;
 568                 *notify = 1;
 569         }
 570 }
 571 #endif