net/ipv6/ila/ila_xlat.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/jhash.h>
   3 #include <linux/netfilter.h>
   4 #include <linux/rcupdate.h>
   5 #include <linux/rhashtable.h>
   6 #include <linux/vmalloc.h>
   7 #include <net/genetlink.h>
   8 #include <net/ila.h>
   9 #include <net/netns/generic.h>
  10 #include <uapi/linux/genetlink.h>
  11 #include "ila.h"
  12
  13 struct ila_xlat_params {
  14         struct ila_params ip;
  15         int ifindex;
  16 };
  17
  18 struct ila_map {
  19         struct ila_xlat_params xp;
  20         struct rhash_head node;
  21         struct ila_map __rcu *next;
  22         struct rcu_head rcu;
  23 };
  24
  25 #define MAX_LOCKS 1024
  26 #define LOCKS_PER_CPU 10
  27
  28 static int alloc_ila_locks(struct ila_net *ilan)
  29 {
  30         return alloc_bucket_spinlocks(&ilan->xlat.locks, &ilan->xlat.locks_mask,
  31                                       MAX_LOCKS, LOCKS_PER_CPU,
  32                                       GFP_KERNEL);
  33 }
  34
  35 static u32 hashrnd __read_mostly;
  36 static __always_inline void __ila_hash_secret_init(void)
  37 {
  38         net_get_random_once(&hashrnd, sizeof(hashrnd));
  39 }
  40
  41 static inline u32 ila_locator_hash(struct ila_locator loc)
  42 {
  43         u32 *v = (u32 *)loc.v32;
  44
  45         __ila_hash_secret_init();
  46         return jhash_2words(v[0], v[1], hashrnd);
  47 }
  48
  49 static inline spinlock_t *ila_get_lock(struct ila_net *ilan,
  50                                        struct ila_locator loc)
  51 {
  52         return &ilan->xlat.locks[ila_locator_hash(loc) & ilan->xlat.locks_mask];
  53 }
  54
  55 static inline int ila_cmp_wildcards(struct ila_map *ila,
  56                                     struct ila_addr *iaddr, int ifindex)
  57 {
  58         return (ila->xp.ifindex && ila->xp.ifindex != ifindex);
  59 }
  60
  61 static inline int ila_cmp_params(struct ila_map *ila,
  62                                  struct ila_xlat_params *xp)
  63 {
  64         return (ila->xp.ifindex != xp->ifindex);
  65 }
  66
  67 static int ila_cmpfn(struct rhashtable_compare_arg *arg,
  68                      const void *obj)
  69 {
  70         const struct ila_map *ila = obj;
  71
  72         return (ila->xp.ip.locator_match.v64 != *(__be64 *)arg->key);
  73 }
  74
  75 static inline int ila_order(struct ila_map *ila)
  76 {
  77         int score = 0;
  78
  79         if (ila->xp.ifindex)
  80                 score += 1 << 1;
  81
  82         return score;
  83 }
  84
  85 static const struct rhashtable_params rht_params = {
  86         .nelem_hint = 1024,
  87         .head_offset = offsetof(struct ila_map, node),
  88         .key_offset = offsetof(struct ila_map, xp.ip.locator_match),
  89         .key_len = sizeof(u64), /* identifier */
  90         .max_size = 1048576,
  91         .min_size = 256,
  92         .automatic_shrinking = true,
  93         .obj_cmpfn = ila_cmpfn,
  94 };
  95
  96 static int parse_nl_config(struct genl_info *info,
  97                            struct ila_xlat_params *xp)
  98 {
  99         memset(xp, 0, sizeof(*xp));
 100
 101         if (info->attrs[ILA_ATTR_LOCATOR])
 102                 xp->ip.locator.v64 = (__force __be64)nla_get_u64(
 103                         info->attrs[ILA_ATTR_LOCATOR]);
 104
 105         if (info->attrs[ILA_ATTR_LOCATOR_MATCH])
 106                 xp->ip.locator_match.v64 = (__force __be64)nla_get_u64(
 107                         info->attrs[ILA_ATTR_LOCATOR_MATCH]);
 108
 109         if (info->attrs[ILA_ATTR_CSUM_MODE])
 110                 xp->ip.csum_mode = nla_get_u8(info->attrs[ILA_ATTR_CSUM_MODE]);
 111         else
 112                 xp->ip.csum_mode = ILA_CSUM_NO_ACTION;
 113
 114         if (info->attrs[ILA_ATTR_IDENT_TYPE])
 115                 xp->ip.ident_type = nla_get_u8(
 116                                 info->attrs[ILA_ATTR_IDENT_TYPE]);
 117         else
 118                 xp->ip.ident_type = ILA_ATYPE_USE_FORMAT;
 119
 120         if (info->attrs[ILA_ATTR_IFINDEX])
 121                 xp->ifindex = nla_get_s32(info->attrs[ILA_ATTR_IFINDEX]);
 122
 123         return 0;
 124 }
 125
 126 /* Must be called with rcu readlock */
 127 static inline struct ila_map *ila_lookup_wildcards(struct ila_addr *iaddr,
 128                                                    int ifindex,
 129                                                    struct ila_net *ilan)
 130 {
 131         struct ila_map *ila;
 132
 133         ila = rhashtable_lookup_fast(&ilan->xlat.rhash_table, &iaddr->loc,
 134                                      rht_params);
 135         while (ila) {
 136                 if (!ila_cmp_wildcards(ila, iaddr, ifindex))
 137                         return ila;
 138                 ila = rcu_access_pointer(ila->next);
 139         }
 140
 141         return NULL;
 142 }
 143
 144 /* Must be called with rcu readlock */
 145 static inline struct ila_map *ila_lookup_by_params(struct ila_xlat_params *xp,
 146                                                    struct ila_net *ilan)
 147 {
 148         struct ila_map *ila;
 149
 150         ila = rhashtable_lookup_fast(&ilan->xlat.rhash_table,
 151                                      &xp->ip.locator_match,
 152                                      rht_params);
 153         while (ila) {
 154                 if (!ila_cmp_params(ila, xp))
 155                         return ila;
 156                 ila = rcu_access_pointer(ila->next);
 157         }
 158
 159         return NULL;
 160 }
 161
 162 static inline void ila_release(struct ila_map *ila)
 163 {
 164         kfree_rcu(ila, rcu);
 165 }
 166
 167 static void ila_free_node(struct ila_map *ila)
 168 {
 169         struct ila_map *next;
 170
 171         /* Assume rcu_readlock held */
 172         while (ila) {
 173                 next = rcu_access_pointer(ila->next);
 174                 ila_release(ila);
 175                 ila = next;
 176         }
 177 }
 178
 179 static void ila_free_cb(void *ptr, void *arg)
 180 {
 181         ila_free_node((struct ila_map *)ptr);
 182 }
 183
 184 static int ila_xlat_addr(struct sk_buff *skb, bool sir2ila);
 185
 186 static unsigned int
 187 ila_nf_input(void *priv,
 188              struct sk_buff *skb,
 189              const struct nf_hook_state *state)
 190 {
 191         ila_xlat_addr(skb, false);
 192         return NF_ACCEPT;
 193 }
 194
 195 static const struct nf_hook_ops ila_nf_hook_ops[] = {
 196         {
 197                 .hook = ila_nf_input,
 198                 .pf = NFPROTO_IPV6,
 199                 .hooknum = NF_INET_PRE_ROUTING,
 200                 .priority = -1,
 201         },
 202 };
 203
 204 static int ila_add_mapping(struct net *net, struct ila_xlat_params *xp)
 205 {
 206         struct ila_net *ilan = net_generic(net, ila_net_id);
 207         struct ila_map *ila, *head;
 208         spinlock_t *lock = ila_get_lock(ilan, xp->ip.locator_match);
 209         int err = 0, order;
 210
 211         if (!ilan->xlat.hooks_registered) {
 212                 /* We defer registering net hooks in the namespace until the
 213                  * first mapping is added.
 214                  */
 215                 err = nf_register_net_hooks(net, ila_nf_hook_ops,
 216                                             ARRAY_SIZE(ila_nf_hook_ops));
 217                 if (err)
 218                         return err;
 219
 220                 ilan->xlat.hooks_registered = true;
 221         }
 222
 223         ila = kzalloc(sizeof(*ila), GFP_KERNEL);
 224         if (!ila)
 225                 return -ENOMEM;
 226
 227         ila_init_saved_csum(&xp->ip);
 228
 229         ila->xp = *xp;
 230
 231         order = ila_order(ila);
 232
 233         spin_lock(lock);
 234
 235         head = rhashtable_lookup_fast(&ilan->xlat.rhash_table,
 236                                       &xp->ip.locator_match,
 237                                       rht_params);
 238         if (!head) {
 239                 /* New entry for the rhash_table */
 240                 err = rhashtable_lookup_insert_fast(&ilan->xlat.rhash_table,
 241                                                     &ila->node, rht_params);
 242         } else {
 243                 struct ila_map *tila = head, *prev = NULL;
 244
 245                 do {
 246                         if (!ila_cmp_params(tila, xp)) {
 247                                 err = -EEXIST;
 248                                 goto out;
 249                         }
 250
 251                         if (order > ila_order(tila))
 252                                 break;
 253
 254                         prev = tila;
 255                         tila = rcu_dereference_protected(tila->next,
 256                                 lockdep_is_held(lock));
 257                 } while (tila);
 258
 259                 if (prev) {
 260                         /* Insert in sub list of head */
 261                         RCU_INIT_POINTER(ila->next, tila);
 262                         rcu_assign_pointer(prev->next, ila);
 263                 } else {
 264                         /* Make this ila new head */
 265                         RCU_INIT_POINTER(ila->next, head);
 266                         err = rhashtable_replace_fast(&ilan->xlat.rhash_table,
 267                                                       &head->node,
 268                                                       &ila->node, rht_params);
 269                         if (err)
 270                                 goto out;
 271                 }
 272         }
 273
 274 out:
 275         spin_unlock(lock);
 276
 277         if (err)
 278                 kfree(ila);
 279
 280         return err;
 281 }
 282
 283 static int ila_del_mapping(struct net *net, struct ila_xlat_params *xp)
 284 {
 285         struct ila_net *ilan = net_generic(net, ila_net_id);
 286         struct ila_map *ila, *head, *prev;
 287         spinlock_t *lock = ila_get_lock(ilan, xp->ip.locator_match);
 288         int err = -ENOENT;
 289
 290         spin_lock(lock);
 291
 292         head = rhashtable_lookup_fast(&ilan->xlat.rhash_table,
 293                                       &xp->ip.locator_match, rht_params);
 294         ila = head;
 295
 296         prev = NULL;
 297
 298         while (ila) {
 299                 if (ila_cmp_params(ila, xp)) {
 300                         prev = ila;
 301                         ila = rcu_dereference_protected(ila->next,
 302                                                         lockdep_is_held(lock));
 303                         continue;
 304                 }
 305
 306                 err = 0;
 307
 308                 if (prev) {
 309                         /* Not head, just delete from list */
 310                         rcu_assign_pointer(prev->next, ila->next);
 311                 } else {
 312                         /* It is the head. If there is something in the
 313                          * sublist we need to make a new head.
 314                          */
 315                         head = rcu_dereference_protected(ila->next,
 316                                                          lockdep_is_held(lock));
 317                         if (head) {
 318                                 /* Put first entry in the sublist into the
 319                                  * table
 320                                  */
 321                                 err = rhashtable_replace_fast(
 322                                         &ilan->xlat.rhash_table, &ila->node,
 323                                         &head->node, rht_params);
 324                                 if (err)
 325                                         goto out;
 326                         } else {
 327                                 /* Entry no longer used */
 328                                 err = rhashtable_remove_fast(
 329                                                 &ilan->xlat.rhash_table,
 330                                                 &ila->node, rht_params);
 331                         }
 332                 }
 333
 334                 ila_release(ila);
 335
 336                 break;
 337         }
 338
 339 out:
 340         spin_unlock(lock);
 341
 342         return err;
 343 }
 344
 345 int ila_xlat_nl_cmd_add_mapping(struct sk_buff *skb, struct genl_info *info)
 346 {
 347         struct net *net = genl_info_net(info);
 348         struct ila_xlat_params p;
 349         int err;
 350
 351         err = parse_nl_config(info, &p);
 352         if (err)
 353                 return err;
 354
 355         return ila_add_mapping(net, &p);
 356 }
 357
 358 int ila_xlat_nl_cmd_del_mapping(struct sk_buff *skb, struct genl_info *info)
 359 {
 360         struct net *net = genl_info_net(info);
 361         struct ila_xlat_params xp;
 362         int err;
 363
 364         err = parse_nl_config(info, &xp);
 365         if (err)
 366                 return err;
 367
 368         ila_del_mapping(net, &xp);
 369
 370         return 0;
 371 }
 372
 373 static inline spinlock_t *lock_from_ila_map(struct ila_net *ilan,
 374                                             struct ila_map *ila)
 375 {
 376         return ila_get_lock(ilan, ila->xp.ip.locator_match);
 377 }
 378
 379 int ila_xlat_nl_cmd_flush(struct sk_buff *skb, struct genl_info *info)
 380 {
 381         struct net *net = genl_info_net(info);
 382         struct ila_net *ilan = net_generic(net, ila_net_id);
 383         struct rhashtable_iter iter;
 384         struct ila_map *ila;
 385         spinlock_t *lock;
 386         int ret;
 387
 388         ret = rhashtable_walk_init(&ilan->xlat.rhash_table, &iter, GFP_KERNEL);
 389         if (ret)
 390                 goto done;
 391
 392         rhashtable_walk_start(&iter);
 393
 394         for (;;) {
 395                 ila = rhashtable_walk_next(&iter);
 396
 397                 if (IS_ERR(ila)) {
 398                         if (PTR_ERR(ila) == -EAGAIN)
 399                                 continue;
 400                         ret = PTR_ERR(ila);
 401                         goto done;
 402                 } else if (!ila) {
 403                         break;
 404                 }
 405
 406                 lock = lock_from_ila_map(ilan, ila);
 407
 408                 spin_lock(lock);
 409
 410                 ret = rhashtable_remove_fast(&ilan->xlat.rhash_table,
 411                                              &ila->node, rht_params);
 412                 if (!ret)
 413                         ila_free_node(ila);
 414
 415                 spin_unlock(lock);
 416
 417                 if (ret)
 418                         break;
 419         }
 420
 421 done:
 422         rhashtable_walk_stop(&iter);
 423         rhashtable_walk_exit(&iter);
 424         return ret;
 425 }
 426
 427 static int ila_fill_info(struct ila_map *ila, struct sk_buff *msg)
 428 {
 429         if (nla_put_u64_64bit(msg, ILA_ATTR_LOCATOR,
 430                               (__force u64)ila->xp.ip.locator.v64,
 431                               ILA_ATTR_PAD) ||
 432             nla_put_u64_64bit(msg, ILA_ATTR_LOCATOR_MATCH,
 433                               (__force u64)ila->xp.ip.locator_match.v64,
 434                               ILA_ATTR_PAD) ||
 435             nla_put_s32(msg, ILA_ATTR_IFINDEX, ila->xp.ifindex) ||
 436             nla_put_u8(msg, ILA_ATTR_CSUM_MODE, ila->xp.ip.csum_mode) ||
 437             nla_put_u8(msg, ILA_ATTR_IDENT_TYPE, ila->xp.ip.ident_type))
 438                 return -1;
 439
 440         return 0;
 441 }
 442
 443 static int ila_dump_info(struct ila_map *ila,
 444                          u32 portid, u32 seq, u32 flags,
 445                          struct sk_buff *skb, u8 cmd)
 446 {
 447         void *hdr;
 448
 449         hdr = genlmsg_put(skb, portid, seq, &ila_nl_family, flags, cmd);
 450         if (!hdr)
 451                 return -ENOMEM;
 452
 453         if (ila_fill_info(ila, skb) < 0)
 454                 goto nla_put_failure;
 455
 456         genlmsg_end(skb, hdr);
 457         return 0;
 458
 459 nla_put_failure:
 460         genlmsg_cancel(skb, hdr);
 461         return -EMSGSIZE;
 462 }
 463
 464 int ila_xlat_nl_cmd_get_mapping(struct sk_buff *skb, struct genl_info *info)
 465 {
 466         struct net *net = genl_info_net(info);
 467         struct ila_net *ilan = net_generic(net, ila_net_id);
 468         struct sk_buff *msg;
 469         struct ila_xlat_params xp;
 470         struct ila_map *ila;
 471         int ret;
 472
 473         ret = parse_nl_config(info, &xp);
 474         if (ret)
 475                 return ret;
 476
 477         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 478         if (!msg)
 479                 return -ENOMEM;
 480
 481         rcu_read_lock();
 482
 483         ila = ila_lookup_by_params(&xp, ilan);
 484         if (ila) {
 485                 ret = ila_dump_info(ila,
 486                                     info->snd_portid,
 487                                     info->snd_seq, 0, msg,
 488                                     info->genlhdr->cmd);
 489         }
 490
 491         rcu_read_unlock();
 492
 493         if (ret < 0)
 494                 goto out_free;
 495
 496         return genlmsg_reply(msg, info);
 497
 498 out_free:
 499         nlmsg_free(msg);
 500         return ret;
 501 }
 502
 503 struct ila_dump_iter {
 504         struct rhashtable_iter rhiter;
 505         int skip;
 506 };
 507
 508 int ila_xlat_nl_dump_start(struct netlink_callback *cb)
 509 {
 510         struct net *net = sock_net(cb->skb->sk);
 511         struct ila_net *ilan = net_generic(net, ila_net_id);
 512         struct ila_dump_iter *iter;
 513         int ret;
 514
 515         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 516         if (!iter)
 517                 return -ENOMEM;
 518
 519         ret = rhashtable_walk_init(&ilan->xlat.rhash_table, &iter->rhiter,
 520                                    GFP_KERNEL);
 521         if (ret) {
 522                 kfree(iter);
 523                 return ret;
 524         }
 525
 526         iter->skip = 0;
 527         cb->args[0] = (long)iter;
 528
 529         return ret;
 530 }
 531
 532 int ila_xlat_nl_dump_done(struct netlink_callback *cb)
 533 {
 534         struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args[0];
 535
 536         rhashtable_walk_exit(&iter->rhiter);
 537
 538         kfree(iter);
 539
 540         return 0;
 541 }
 542
 543 int ila_xlat_nl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 544 {
 545         struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args[0];
 546         struct rhashtable_iter *rhiter = &iter->rhiter;
 547         int skip = iter->skip;
 548         struct ila_map *ila;
 549         int ret;
 550
 551         rhashtable_walk_start(rhiter);
 552
 553         /* Get first entry */
 554         ila = rhashtable_walk_peek(rhiter);
 555
 556         if (ila && !IS_ERR(ila) && skip) {
 557                 /* Skip over visited entries */
 558
 559                 while (ila && skip) {
 560                         /* Skip over any ila entries in this list that we
 561                          * have already dumped.
 562                          */
 563                         ila = rcu_access_pointer(ila->next);
 564                         skip--;
 565                 }
 566         }
 567
 568         skip = 0;
 569
 570         for (;;) {
 571                 if (IS_ERR(ila)) {
 572                         ret = PTR_ERR(ila);
 573                         if (ret == -EAGAIN) {
 574                                 /* Table has changed and iter has reset. Return
 575                                  * -EAGAIN to the application even if we have
 576                                  * written data to the skb. The application
 577                                  * needs to deal with this.
 578                                  */
 579
 580                                 goto out_ret;
 581                         } else {
 582                                 break;
 583                         }
 584                 } else if (!ila) {
 585                         ret = 0;
 586                         break;
 587                 }
 588
 589                 while (ila) {
 590                         ret =  ila_dump_info(ila, NETLINK_CB(cb->skb).portid,
 591                                              cb->nlh->nlmsg_seq, NLM_F_MULTI,
 592                                              skb, ILA_CMD_GET);
 593                         if (ret)
 594                                 goto out;
 595
 596                         skip++;
 597                         ila = rcu_access_pointer(ila->next);
 598                 }
 599
 600                 skip = 0;
 601                 ila = rhashtable_walk_next(rhiter);
 602         }
 603
 604 out:
 605         iter->skip = skip;
 606         ret = (skb->len ? : ret);
 607
 608 out_ret:
 609         rhashtable_walk_stop(rhiter);
 610         return ret;
 611 }
 612
 613 #define ILA_HASH_TABLE_SIZE 1024
 614
 615 int ila_xlat_init_net(struct net *net)
 616 {
 617         struct ila_net *ilan = net_generic(net, ila_net_id);
 618         int err;
 619
 620         err = alloc_ila_locks(ilan);
 621         if (err)
 622                 return err;
 623
 624         rhashtable_init(&ilan->xlat.rhash_table, &rht_params);
 625
 626         return 0;
 627 }
 628
 629 void ila_xlat_exit_net(struct net *net)
 630 {
 631         struct ila_net *ilan = net_generic(net, ila_net_id);
 632
 633         rhashtable_free_and_destroy(&ilan->xlat.rhash_table, ila_free_cb, NULL);
 634
 635         free_bucket_spinlocks(ilan->xlat.locks);
 636
 637         if (ilan->xlat.hooks_registered)
 638                 nf_unregister_net_hooks(net, ila_nf_hook_ops,
 639                                         ARRAY_SIZE(ila_nf_hook_ops));
 640 }
 641
 642 static int ila_xlat_addr(struct sk_buff *skb, bool sir2ila)
 643 {
 644         struct ila_map *ila;
 645         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 646         struct net *net = dev_net(skb->dev);
 647         struct ila_net *ilan = net_generic(net, ila_net_id);
 648         struct ila_addr *iaddr = ila_a2i(&ip6h->daddr);
 649
 650         /* Assumes skb contains a valid IPv6 header that is pulled */
 651
 652         /* No check here that ILA type in the mapping matches what is in the
 653          * address. We assume that whatever sender gaves us can be translated.
 654          * The checksum mode however is relevant.
 655          */
 656
 657         rcu_read_lock();
 658
 659         ila = ila_lookup_wildcards(iaddr, skb->dev->ifindex, ilan);
 660         if (ila)
 661                 ila_update_ipv6_locator(skb, &ila->xp.ip, sir2ila);
 662
 663         rcu_read_unlock();
 664
 665         return 0;
 666 }