net/netfilter/nft_set_rbtree.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   4  *
   5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/list.h>
  12 #include <linux/rbtree.h>
  13 #include <linux/netlink.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter/nf_tables.h>
  16 #include <net/netfilter/nf_tables_core.h>
  17
  18 struct nft_rbtree {
  19         struct rb_root          root;
  20         rwlock_t                lock;
  21         seqcount_t              count;
  22         struct delayed_work     gc_work;
  23 };
  24
  25 struct nft_rbtree_elem {
  26         struct rb_node          node;
  27         struct nft_set_ext      ext;
  28 };
  29
  30 static bool nft_rbtree_interval_end(const struct nft_rbtree_elem *rbe)
  31 {
  32         return nft_set_ext_exists(&rbe->ext, NFT_SET_EXT_FLAGS) &&
  33                (*nft_set_ext_flags(&rbe->ext) & NFT_SET_ELEM_INTERVAL_END);
  34 }
  35
  36 static bool nft_rbtree_interval_start(const struct nft_rbtree_elem *rbe)
  37 {
  38         return !nft_rbtree_interval_end(rbe);
  39 }
  40
  41 static bool nft_rbtree_equal(const struct nft_set *set, const void *this,
  42                              const struct nft_rbtree_elem *interval)
  43 {
  44         return memcmp(this, nft_set_ext_key(&interval->ext), set->klen) == 0;
  45 }
  46
  47 static bool __nft_rbtree_lookup(const struct net *net, const struct nft_set *set,
  48                                 const u32 *key, const struct nft_set_ext **ext,
  49                                 unsigned int seq)
  50 {
  51         struct nft_rbtree *priv = nft_set_priv(set);
  52         const struct nft_rbtree_elem *rbe, *interval = NULL;
  53         u8 genmask = nft_genmask_cur(net);
  54         const struct rb_node *parent;
  55         const void *this;
  56         int d;
  57
  58         parent = rcu_dereference_raw(priv->root.rb_node);
  59         while (parent != NULL) {
  60                 if (read_seqcount_retry(&priv->count, seq))
  61                         return false;
  62
  63                 rbe = rb_entry(parent, struct nft_rbtree_elem, node);
  64
  65                 this = nft_set_ext_key(&rbe->ext);
  66                 d = memcmp(this, key, set->klen);
  67                 if (d < 0) {
  68                         parent = rcu_dereference_raw(parent->rb_left);
  69                         if (interval &&
  70                             nft_rbtree_equal(set, this, interval) &&
  71                             nft_rbtree_interval_end(rbe) &&
  72                             nft_rbtree_interval_start(interval))
  73                                 continue;
  74                         interval = rbe;
  75                 } else if (d > 0)
  76                         parent = rcu_dereference_raw(parent->rb_right);
  77                 else {
  78                         if (!nft_set_elem_active(&rbe->ext, genmask)) {
  79                                 parent = rcu_dereference_raw(parent->rb_left);
  80                                 continue;
  81                         }
  82
  83                         if (nft_set_elem_expired(&rbe->ext))
  84                                 return false;
  85
  86                         if (nft_rbtree_interval_end(rbe)) {
  87                                 if (nft_set_is_anonymous(set))
  88                                         return false;
  89                                 parent = rcu_dereference_raw(parent->rb_left);
  90                                 interval = NULL;
  91                                 continue;
  92                         }
  93
  94                         *ext = &rbe->ext;
  95                         return true;
  96                 }
  97         }
  98
  99         if (set->flags & NFT_SET_INTERVAL && interval != NULL &&
 100             nft_set_elem_active(&interval->ext, genmask) &&
 101             !nft_set_elem_expired(&interval->ext) &&
 102             nft_rbtree_interval_start(interval)) {
 103                 *ext = &interval->ext;
 104                 return true;
 105         }
 106
 107         return false;
 108 }
 109
 110 static bool nft_rbtree_lookup(const struct net *net, const struct nft_set *set,
 111                               const u32 *key, const struct nft_set_ext **ext)
 112 {
 113         struct nft_rbtree *priv = nft_set_priv(set);
 114         unsigned int seq = read_seqcount_begin(&priv->count);
 115         bool ret;
 116
 117         ret = __nft_rbtree_lookup(net, set, key, ext, seq);
 118         if (ret || !read_seqcount_retry(&priv->count, seq))
 119                 return ret;
 120
 121         read_lock_bh(&priv->lock);
 122         seq = read_seqcount_begin(&priv->count);
 123         ret = __nft_rbtree_lookup(net, set, key, ext, seq);
 124         read_unlock_bh(&priv->lock);
 125
 126         return ret;
 127 }
 128
 129 static bool __nft_rbtree_get(const struct net *net, const struct nft_set *set,
 130                              const u32 *key, struct nft_rbtree_elem **elem,
 131                              unsigned int seq, unsigned int flags, u8 genmask)
 132 {
 133         struct nft_rbtree_elem *rbe, *interval = NULL;
 134         struct nft_rbtree *priv = nft_set_priv(set);
 135         const struct rb_node *parent;
 136         const void *this;
 137         int d;
 138
 139         parent = rcu_dereference_raw(priv->root.rb_node);
 140         while (parent != NULL) {
 141                 if (read_seqcount_retry(&priv->count, seq))
 142                         return false;
 143
 144                 rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 145
 146                 this = nft_set_ext_key(&rbe->ext);
 147                 d = memcmp(this, key, set->klen);
 148                 if (d < 0) {
 149                         parent = rcu_dereference_raw(parent->rb_left);
 150                         if (!(flags & NFT_SET_ELEM_INTERVAL_END))
 151                                 interval = rbe;
 152                 } else if (d > 0) {
 153                         parent = rcu_dereference_raw(parent->rb_right);
 154                         if (flags & NFT_SET_ELEM_INTERVAL_END)
 155                                 interval = rbe;
 156                 } else {
 157                         if (!nft_set_elem_active(&rbe->ext, genmask)) {
 158                                 parent = rcu_dereference_raw(parent->rb_left);
 159                                 continue;
 160                         }
 161
 162                         if (nft_set_elem_expired(&rbe->ext))
 163                                 return false;
 164
 165                         if (!nft_set_ext_exists(&rbe->ext, NFT_SET_EXT_FLAGS) ||
 166                             (*nft_set_ext_flags(&rbe->ext) & NFT_SET_ELEM_INTERVAL_END) ==
 167                             (flags & NFT_SET_ELEM_INTERVAL_END)) {
 168                                 *elem = rbe;
 169                                 return true;
 170                         }
 171
 172                         if (nft_rbtree_interval_end(rbe))
 173                                 interval = NULL;
 174
 175                         parent = rcu_dereference_raw(parent->rb_left);
 176                 }
 177         }
 178
 179         if (set->flags & NFT_SET_INTERVAL && interval != NULL &&
 180             nft_set_elem_active(&interval->ext, genmask) &&
 181             !nft_set_elem_expired(&interval->ext) &&
 182             ((!nft_rbtree_interval_end(interval) &&
 183               !(flags & NFT_SET_ELEM_INTERVAL_END)) ||
 184              (nft_rbtree_interval_end(interval) &&
 185               (flags & NFT_SET_ELEM_INTERVAL_END)))) {
 186                 *elem = interval;
 187                 return true;
 188         }
 189
 190         return false;
 191 }
 192
 193 static void *nft_rbtree_get(const struct net *net, const struct nft_set *set,
 194                             const struct nft_set_elem *elem, unsigned int flags)
 195 {
 196         struct nft_rbtree *priv = nft_set_priv(set);
 197         unsigned int seq = read_seqcount_begin(&priv->count);
 198         struct nft_rbtree_elem *rbe = ERR_PTR(-ENOENT);
 199         const u32 *key = (const u32 *)&elem->key.val;
 200         u8 genmask = nft_genmask_cur(net);
 201         bool ret;
 202
 203         ret = __nft_rbtree_get(net, set, key, &rbe, seq, flags, genmask);
 204         if (ret || !read_seqcount_retry(&priv->count, seq))
 205                 return rbe;
 206
 207         read_lock_bh(&priv->lock);
 208         seq = read_seqcount_begin(&priv->count);
 209         ret = __nft_rbtree_get(net, set, key, &rbe, seq, flags, genmask);
 210         if (!ret)
 211                 rbe = ERR_PTR(-ENOENT);
 212         read_unlock_bh(&priv->lock);
 213
 214         return rbe;
 215 }
 216
 217 static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 218                                struct nft_rbtree_elem *new,
 219                                struct nft_set_ext **ext)
 220 {
 221         struct nft_rbtree *priv = nft_set_priv(set);
 222         u8 genmask = nft_genmask_next(net);
 223         struct nft_rbtree_elem *rbe;
 224         struct rb_node *parent, **p;
 225         bool overlap = false;
 226         int d;
 227
 228         /* Detect overlaps as we descend the tree. Set the flag in these cases:
 229          *
 230          * a1. _ _ __>|  ?_ _ __|  (insert end before existing end)
 231          * a2. _ _ ___|  ?_ _ _>|  (insert end after existing end)
 232          * a3. _ _ ___? >|_ _ __|  (insert start before existing end)
 233          *
 234          * and clear it later on, as we eventually reach the points indicated by
 235          * '?' above, in the cases described below. We'll always meet these
 236          * later, locally, due to tree ordering, and overlaps for the intervals
 237          * that are the closest together are always evaluated last.
 238          *
 239          * b1. _ _ __>|  !_ _ __|  (insert end before existing start)
 240          * b2. _ _ ___|  !_ _ _>|  (insert end after existing start)
 241          * b3. _ _ ___! >|_ _ __|  (insert start after existing end)
 242          *
 243          * Case a3. resolves to b3.:
 244          * - if the inserted start element is the leftmost, because the '0'
 245          *   element in the tree serves as end element
 246          * - otherwise, if an existing end is found. Note that end elements are
 247          *   always inserted after corresponding start elements.
 248          *
 249          * For a new, rightmost pair of elements, we'll hit cases b3. and b2.,
 250          * in that order.
 251          *
 252          * The flag is also cleared in two special cases:
 253          *
 254          * b4. |__ _ _!|<_ _ _   (insert start right before existing end)
 255          * b5. |__ _ >|!__ _ _   (insert end right after existing start)
 256          *
 257          * which always happen as last step and imply that no further
 258          * overlapping is possible.
 259          */
 260
 261         parent = NULL;
 262         p = &priv->root.rb_node;
 263         while (*p != NULL) {
 264                 parent = *p;
 265                 rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 266                 d = memcmp(nft_set_ext_key(&rbe->ext),
 267                            nft_set_ext_key(&new->ext),
 268                            set->klen);
 269                 if (d < 0) {
 270                         p = &parent->rb_left;
 271
 272                         if (nft_rbtree_interval_start(new)) {
 273                                 if (nft_rbtree_interval_end(rbe) &&
 274                                     nft_set_elem_active(&rbe->ext, genmask))
 275                                         overlap = false;
 276                         } else {
 277                                 overlap = nft_rbtree_interval_end(rbe) &&
 278                                           nft_set_elem_active(&rbe->ext,
 279                                                               genmask);
 280                         }
 281                 } else if (d > 0) {
 282                         p = &parent->rb_right;
 283
 284                         if (nft_rbtree_interval_end(new)) {
 285                                 overlap = nft_rbtree_interval_end(rbe) &&
 286                                           nft_set_elem_active(&rbe->ext,
 287                                                               genmask);
 288                         } else if (nft_rbtree_interval_end(rbe) &&
 289                                    nft_set_elem_active(&rbe->ext, genmask)) {
 290                                 overlap = true;
 291                         }
 292                 } else {
 293                         if (nft_rbtree_interval_end(rbe) &&
 294                             nft_rbtree_interval_start(new)) {
 295                                 p = &parent->rb_left;
 296
 297                                 if (nft_set_elem_active(&rbe->ext, genmask))
 298                                         overlap = false;
 299                         } else if (nft_rbtree_interval_start(rbe) &&
 300                                    nft_rbtree_interval_end(new)) {
 301                                 p = &parent->rb_right;
 302
 303                                 if (nft_set_elem_active(&rbe->ext, genmask))
 304                                         overlap = false;
 305                         } else if (nft_set_elem_active(&rbe->ext, genmask)) {
 306                                 *ext = &rbe->ext;
 307                                 return -EEXIST;
 308                         } else {
 309                                 p = &parent->rb_left;
 310                         }
 311                 }
 312         }
 313
 314         if (overlap)
 315                 return -ENOTEMPTY;
 316
 317         rb_link_node_rcu(&new->node, parent, p);
 318         rb_insert_color(&new->node, &priv->root);
 319         return 0;
 320 }
 321
 322 static int nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 323                              const struct nft_set_elem *elem,
 324                              struct nft_set_ext **ext)
 325 {
 326         struct nft_rbtree *priv = nft_set_priv(set);
 327         struct nft_rbtree_elem *rbe = elem->priv;
 328         int err;
 329
 330         write_lock_bh(&priv->lock);
 331         write_seqcount_begin(&priv->count);
 332         err = __nft_rbtree_insert(net, set, rbe, ext);
 333         write_seqcount_end(&priv->count);
 334         write_unlock_bh(&priv->lock);
 335
 336         return err;
 337 }
 338
 339 static void nft_rbtree_remove(const struct net *net,
 340                               const struct nft_set *set,
 341                               const struct nft_set_elem *elem)
 342 {
 343         struct nft_rbtree *priv = nft_set_priv(set);
 344         struct nft_rbtree_elem *rbe = elem->priv;
 345
 346         write_lock_bh(&priv->lock);
 347         write_seqcount_begin(&priv->count);
 348         rb_erase(&rbe->node, &priv->root);
 349         write_seqcount_end(&priv->count);
 350         write_unlock_bh(&priv->lock);
 351 }
 352
 353 static void nft_rbtree_activate(const struct net *net,
 354                                 const struct nft_set *set,
 355                                 const struct nft_set_elem *elem)
 356 {
 357         struct nft_rbtree_elem *rbe = elem->priv;
 358
 359         nft_set_elem_change_active(net, set, &rbe->ext);
 360         nft_set_elem_clear_busy(&rbe->ext);
 361 }
 362
 363 static bool nft_rbtree_flush(const struct net *net,
 364                              const struct nft_set *set, void *priv)
 365 {
 366         struct nft_rbtree_elem *rbe = priv;
 367
 368         if (!nft_set_elem_mark_busy(&rbe->ext) ||
 369             !nft_is_active(net, &rbe->ext)) {
 370                 nft_set_elem_change_active(net, set, &rbe->ext);
 371                 return true;
 372         }
 373         return false;
 374 }
 375
 376 static void *nft_rbtree_deactivate(const struct net *net,
 377                                    const struct nft_set *set,
 378                                    const struct nft_set_elem *elem)
 379 {
 380         const struct nft_rbtree *priv = nft_set_priv(set);
 381         const struct rb_node *parent = priv->root.rb_node;
 382         struct nft_rbtree_elem *rbe, *this = elem->priv;
 383         u8 genmask = nft_genmask_next(net);
 384         int d;
 385
 386         while (parent != NULL) {
 387                 rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 388
 389                 d = memcmp(nft_set_ext_key(&rbe->ext), &elem->key.val,
 390                                            set->klen);
 391                 if (d < 0)
 392                         parent = parent->rb_left;
 393                 else if (d > 0)
 394                         parent = parent->rb_right;
 395                 else {
 396                         if (nft_rbtree_interval_end(rbe) &&
 397                             nft_rbtree_interval_start(this)) {
 398                                 parent = parent->rb_left;
 399                                 continue;
 400                         } else if (nft_rbtree_interval_start(rbe) &&
 401                                    nft_rbtree_interval_end(this)) {
 402                                 parent = parent->rb_right;
 403                                 continue;
 404                         } else if (!nft_set_elem_active(&rbe->ext, genmask)) {
 405                                 parent = parent->rb_left;
 406                                 continue;
 407                         }
 408                         nft_rbtree_flush(net, set, rbe);
 409                         return rbe;
 410                 }
 411         }
 412         return NULL;
 413 }
 414
 415 static void nft_rbtree_walk(const struct nft_ctx *ctx,
 416                             struct nft_set *set,
 417                             struct nft_set_iter *iter)
 418 {
 419         struct nft_rbtree *priv = nft_set_priv(set);
 420         struct nft_rbtree_elem *rbe;
 421         struct nft_set_elem elem;
 422         struct rb_node *node;
 423
 424         read_lock_bh(&priv->lock);
 425         for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
 426                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 427
 428                 if (iter->count < iter->skip)
 429                         goto cont;
 430                 if (nft_set_elem_expired(&rbe->ext))
 431                         goto cont;
 432                 if (!nft_set_elem_active(&rbe->ext, iter->genmask))
 433                         goto cont;
 434
 435                 elem.priv = rbe;
 436
 437                 iter->err = iter->fn(ctx, set, iter, &elem);
 438                 if (iter->err < 0) {
 439                         read_unlock_bh(&priv->lock);
 440                         return;
 441                 }
 442 cont:
 443                 iter->count++;
 444         }
 445         read_unlock_bh(&priv->lock);
 446 }
 447
 448 static void nft_rbtree_gc(struct work_struct *work)
 449 {
 450         struct nft_rbtree_elem *rbe, *rbe_end = NULL, *rbe_prev = NULL;
 451         struct nft_set_gc_batch *gcb = NULL;
 452         struct nft_rbtree *priv;
 453         struct rb_node *node;
 454         struct nft_set *set;
 455
 456         priv = container_of(work, struct nft_rbtree, gc_work.work);
 457         set  = nft_set_container_of(priv);
 458
 459         write_lock_bh(&priv->lock);
 460         write_seqcount_begin(&priv->count);
 461         for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
 462                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 463
 464                 if (nft_rbtree_interval_end(rbe)) {
 465                         rbe_end = rbe;
 466                         continue;
 467                 }
 468                 if (!nft_set_elem_expired(&rbe->ext))
 469                         continue;
 470                 if (nft_set_elem_mark_busy(&rbe->ext))
 471                         continue;
 472
 473                 if (rbe_prev) {
 474                         rb_erase(&rbe_prev->node, &priv->root);
 475                         rbe_prev = NULL;
 476                 }
 477                 gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
 478                 if (!gcb)
 479                         break;
 480
 481                 atomic_dec(&set->nelems);
 482                 nft_set_gc_batch_add(gcb, rbe);
 483                 rbe_prev = rbe;
 484
 485                 if (rbe_end) {
 486                         atomic_dec(&set->nelems);
 487                         nft_set_gc_batch_add(gcb, rbe_end);
 488                         rb_erase(&rbe_end->node, &priv->root);
 489                         rbe_end = NULL;
 490                 }
 491                 node = rb_next(node);
 492                 if (!node)
 493                         break;
 494         }
 495         if (rbe_prev)
 496                 rb_erase(&rbe_prev->node, &priv->root);
 497         write_seqcount_end(&priv->count);
 498         write_unlock_bh(&priv->lock);
 499
 500         nft_set_gc_batch_complete(gcb);
 501
 502         queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 503                            nft_set_gc_interval(set));
 504 }
 505
 506 static u64 nft_rbtree_privsize(const struct nlattr * const nla[],
 507                                const struct nft_set_desc *desc)
 508 {
 509         return sizeof(struct nft_rbtree);
 510 }
 511
 512 static int nft_rbtree_init(const struct nft_set *set,
 513                            const struct nft_set_desc *desc,
 514                            const struct nlattr * const nla[])
 515 {
 516         struct nft_rbtree *priv = nft_set_priv(set);
 517
 518         rwlock_init(&priv->lock);
 519         seqcount_init(&priv->count);
 520         priv->root = RB_ROOT;
 521
 522         INIT_DEFERRABLE_WORK(&priv->gc_work, nft_rbtree_gc);
 523         if (set->flags & NFT_SET_TIMEOUT)
 524                 queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 525                                    nft_set_gc_interval(set));
 526
 527         return 0;
 528 }
 529
 530 static void nft_rbtree_destroy(const struct nft_set *set)
 531 {
 532         struct nft_rbtree *priv = nft_set_priv(set);
 533         struct nft_rbtree_elem *rbe;
 534         struct rb_node *node;
 535
 536         cancel_delayed_work_sync(&priv->gc_work);
 537         rcu_barrier();
 538         while ((node = priv->root.rb_node) != NULL) {
 539                 rb_erase(node, &priv->root);
 540                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 541                 nft_set_elem_destroy(set, rbe, true);
 542         }
 543 }
 544
 545 static bool nft_rbtree_estimate(const struct nft_set_desc *desc, u32 features,
 546                                 struct nft_set_estimate *est)
 547 {
 548         if (desc->field_count > 1)
 549                 return false;
 550
 551         if (desc->size)
 552                 est->size = sizeof(struct nft_rbtree) +
 553                             desc->size * sizeof(struct nft_rbtree_elem);
 554         else
 555                 est->size = ~0;
 556
 557         est->lookup = NFT_SET_CLASS_O_LOG_N;
 558         est->space  = NFT_SET_CLASS_O_N;
 559
 560         return true;
 561 }
 562
 563 const struct nft_set_type nft_set_rbtree_type = {
 564         .features       = NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT | NFT_SET_TIMEOUT,
 565         .ops            = {
 566                 .privsize       = nft_rbtree_privsize,
 567                 .elemsize       = offsetof(struct nft_rbtree_elem, ext),
 568                 .estimate       = nft_rbtree_estimate,
 569                 .init           = nft_rbtree_init,
 570                 .destroy        = nft_rbtree_destroy,
 571                 .insert         = nft_rbtree_insert,
 572                 .remove         = nft_rbtree_remove,
 573                 .deactivate     = nft_rbtree_deactivate,
 574                 .flush          = nft_rbtree_flush,
 575                 .activate       = nft_rbtree_activate,
 576                 .lookup         = nft_rbtree_lookup,
 577                 .walk           = nft_rbtree_walk,
 578                 .get            = nft_rbtree_get,
 579         },
 580 };