net/netfilter/nft_set_rbtree.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <[email protected]>
   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                                     !nft_set_elem_expired(&rbe->ext))
 276                                         overlap = false;
 277                         } else {
 278                                 overlap = nft_rbtree_interval_end(rbe) &&
 279                                           nft_set_elem_active(&rbe->ext,
 280                                                               genmask) &&
 281                                           !nft_set_elem_expired(&rbe->ext);
 282                         }
 283                 } else if (d > 0) {
 284                         p = &parent->rb_right;
 285
 286                         if (nft_rbtree_interval_end(new)) {
 287                                 overlap = nft_rbtree_interval_end(rbe) &&
 288                                           nft_set_elem_active(&rbe->ext,
 289                                                               genmask) &&
 290                                           !nft_set_elem_expired(&rbe->ext);
 291                         } else if (nft_rbtree_interval_end(rbe) &&
 292                                    nft_set_elem_active(&rbe->ext, genmask) &&
 293                                    !nft_set_elem_expired(&rbe->ext)) {
 294                                 overlap = true;
 295                         }
 296                 } else {
 297                         if (nft_rbtree_interval_end(rbe) &&
 298                             nft_rbtree_interval_start(new)) {
 299                                 p = &parent->rb_left;
 300
 301                                 if (nft_set_elem_active(&rbe->ext, genmask) &&
 302                                     !nft_set_elem_expired(&rbe->ext))
 303                                         overlap = false;
 304                         } else if (nft_rbtree_interval_start(rbe) &&
 305                                    nft_rbtree_interval_end(new)) {
 306                                 p = &parent->rb_right;
 307
 308                                 if (nft_set_elem_active(&rbe->ext, genmask) &&
 309                                     !nft_set_elem_expired(&rbe->ext))
 310                                         overlap = false;
 311                         } else if (nft_set_elem_active(&rbe->ext, genmask) &&
 312                                    !nft_set_elem_expired(&rbe->ext)) {
 313                                 *ext = &rbe->ext;
 314                                 return -EEXIST;
 315                         } else {
 316                                 p = &parent->rb_left;
 317                         }
 318                 }
 319         }
 320
 321         if (overlap)
 322                 return -ENOTEMPTY;
 323
 324         rb_link_node_rcu(&new->node, parent, p);
 325         rb_insert_color(&new->node, &priv->root);
 326         return 0;
 327 }
 328
 329 static int nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 330                              const struct nft_set_elem *elem,
 331                              struct nft_set_ext **ext)
 332 {
 333         struct nft_rbtree *priv = nft_set_priv(set);
 334         struct nft_rbtree_elem *rbe = elem->priv;
 335         int err;
 336
 337         write_lock_bh(&priv->lock);
 338         write_seqcount_begin(&priv->count);
 339         err = __nft_rbtree_insert(net, set, rbe, ext);
 340         write_seqcount_end(&priv->count);
 341         write_unlock_bh(&priv->lock);
 342
 343         return err;
 344 }
 345
 346 static void nft_rbtree_remove(const struct net *net,
 347                               const struct nft_set *set,
 348                               const struct nft_set_elem *elem)
 349 {
 350         struct nft_rbtree *priv = nft_set_priv(set);
 351         struct nft_rbtree_elem *rbe = elem->priv;
 352
 353         write_lock_bh(&priv->lock);
 354         write_seqcount_begin(&priv->count);
 355         rb_erase(&rbe->node, &priv->root);
 356         write_seqcount_end(&priv->count);
 357         write_unlock_bh(&priv->lock);
 358 }
 359
 360 static void nft_rbtree_activate(const struct net *net,
 361                                 const struct nft_set *set,
 362                                 const struct nft_set_elem *elem)
 363 {
 364         struct nft_rbtree_elem *rbe = elem->priv;
 365
 366         nft_set_elem_change_active(net, set, &rbe->ext);
 367         nft_set_elem_clear_busy(&rbe->ext);
 368 }
 369
 370 static bool nft_rbtree_flush(const struct net *net,
 371                              const struct nft_set *set, void *priv)
 372 {
 373         struct nft_rbtree_elem *rbe = priv;
 374
 375         if (!nft_set_elem_mark_busy(&rbe->ext) ||
 376             !nft_is_active(net, &rbe->ext)) {
 377                 nft_set_elem_change_active(net, set, &rbe->ext);
 378                 return true;
 379         }
 380         return false;
 381 }
 382
 383 static void *nft_rbtree_deactivate(const struct net *net,
 384                                    const struct nft_set *set,
 385                                    const struct nft_set_elem *elem)
 386 {
 387         const struct nft_rbtree *priv = nft_set_priv(set);
 388         const struct rb_node *parent = priv->root.rb_node;
 389         struct nft_rbtree_elem *rbe, *this = elem->priv;
 390         u8 genmask = nft_genmask_next(net);
 391         int d;
 392
 393         while (parent != NULL) {
 394                 rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 395
 396                 d = memcmp(nft_set_ext_key(&rbe->ext), &elem->key.val,
 397                                            set->klen);
 398                 if (d < 0)
 399                         parent = parent->rb_left;
 400                 else if (d > 0)
 401                         parent = parent->rb_right;
 402                 else {
 403                         if (nft_rbtree_interval_end(rbe) &&
 404                             nft_rbtree_interval_start(this)) {
 405                                 parent = parent->rb_left;
 406                                 continue;
 407                         } else if (nft_rbtree_interval_start(rbe) &&
 408                                    nft_rbtree_interval_end(this)) {
 409                                 parent = parent->rb_right;
 410                                 continue;
 411                         } else if (!nft_set_elem_active(&rbe->ext, genmask)) {
 412                                 parent = parent->rb_left;
 413                                 continue;
 414                         }
 415                         nft_rbtree_flush(net, set, rbe);
 416                         return rbe;
 417                 }
 418         }
 419         return NULL;
 420 }
 421
 422 static void nft_rbtree_walk(const struct nft_ctx *ctx,
 423                             struct nft_set *set,
 424                             struct nft_set_iter *iter)
 425 {
 426         struct nft_rbtree *priv = nft_set_priv(set);
 427         struct nft_rbtree_elem *rbe;
 428         struct nft_set_elem elem;
 429         struct rb_node *node;
 430
 431         read_lock_bh(&priv->lock);
 432         for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
 433                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 434
 435                 if (iter->count < iter->skip)
 436                         goto cont;
 437                 if (nft_set_elem_expired(&rbe->ext))
 438                         goto cont;
 439                 if (!nft_set_elem_active(&rbe->ext, iter->genmask))
 440                         goto cont;
 441
 442                 elem.priv = rbe;
 443
 444                 iter->err = iter->fn(ctx, set, iter, &elem);
 445                 if (iter->err < 0) {
 446                         read_unlock_bh(&priv->lock);
 447                         return;
 448                 }
 449 cont:
 450                 iter->count++;
 451         }
 452         read_unlock_bh(&priv->lock);
 453 }
 454
 455 static void nft_rbtree_gc(struct work_struct *work)
 456 {
 457         struct nft_rbtree_elem *rbe, *rbe_end = NULL, *rbe_prev = NULL;
 458         struct nft_set_gc_batch *gcb = NULL;
 459         struct nft_rbtree *priv;
 460         struct rb_node *node;
 461         struct nft_set *set;
 462
 463         priv = container_of(work, struct nft_rbtree, gc_work.work);
 464         set  = nft_set_container_of(priv);
 465
 466         write_lock_bh(&priv->lock);
 467         write_seqcount_begin(&priv->count);
 468         for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
 469                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 470
 471                 if (nft_rbtree_interval_end(rbe)) {
 472                         rbe_end = rbe;
 473                         continue;
 474                 }
 475                 if (!nft_set_elem_expired(&rbe->ext))
 476                         continue;
 477                 if (nft_set_elem_mark_busy(&rbe->ext))
 478                         continue;
 479
 480                 if (rbe_prev) {
 481                         rb_erase(&rbe_prev->node, &priv->root);
 482                         rbe_prev = NULL;
 483                 }
 484                 gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
 485                 if (!gcb)
 486                         break;
 487
 488                 atomic_dec(&set->nelems);
 489                 nft_set_gc_batch_add(gcb, rbe);
 490                 rbe_prev = rbe;
 491
 492                 if (rbe_end) {
 493                         atomic_dec(&set->nelems);
 494                         nft_set_gc_batch_add(gcb, rbe_end);
 495                         rb_erase(&rbe_end->node, &priv->root);
 496                         rbe_end = NULL;
 497                 }
 498                 node = rb_next(node);
 499                 if (!node)
 500                         break;
 501         }
 502         if (rbe_prev)
 503                 rb_erase(&rbe_prev->node, &priv->root);
 504         write_seqcount_end(&priv->count);
 505         write_unlock_bh(&priv->lock);
 506
 507         nft_set_gc_batch_complete(gcb);
 508
 509         queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 510                            nft_set_gc_interval(set));
 511 }
 512
 513 static u64 nft_rbtree_privsize(const struct nlattr * const nla[],
 514                                const struct nft_set_desc *desc)
 515 {
 516         return sizeof(struct nft_rbtree);
 517 }
 518
 519 static int nft_rbtree_init(const struct nft_set *set,
 520                            const struct nft_set_desc *desc,
 521                            const struct nlattr * const nla[])
 522 {
 523         struct nft_rbtree *priv = nft_set_priv(set);
 524
 525         rwlock_init(&priv->lock);
 526         seqcount_init(&priv->count);
 527         priv->root = RB_ROOT;
 528
 529         INIT_DEFERRABLE_WORK(&priv->gc_work, nft_rbtree_gc);
 530         if (set->flags & NFT_SET_TIMEOUT)
 531                 queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 532                                    nft_set_gc_interval(set));
 533
 534         return 0;
 535 }
 536
 537 static void nft_rbtree_destroy(const struct nft_set *set)
 538 {
 539         struct nft_rbtree *priv = nft_set_priv(set);
 540         struct nft_rbtree_elem *rbe;
 541         struct rb_node *node;
 542
 543         cancel_delayed_work_sync(&priv->gc_work);
 544         rcu_barrier();
 545         while ((node = priv->root.rb_node) != NULL) {
 546                 rb_erase(node, &priv->root);
 547                 rbe = rb_entry(node, struct nft_rbtree_elem, node);
 548                 nft_set_elem_destroy(set, rbe, true);
 549         }
 550 }
 551
 552 static bool nft_rbtree_estimate(const struct nft_set_desc *desc, u32 features,
 553                                 struct nft_set_estimate *est)
 554 {
 555         if (desc->field_count > 1)
 556                 return false;
 557
 558         if (desc->size)
 559                 est->size = sizeof(struct nft_rbtree) +
 560                             desc->size * sizeof(struct nft_rbtree_elem);
 561         else
 562                 est->size = ~0;
 563
 564         est->lookup = NFT_SET_CLASS_O_LOG_N;
 565         est->space  = NFT_SET_CLASS_O_N;
 566
 567         return true;
 568 }
 569
 570 const struct nft_set_type nft_set_rbtree_type = {
 571         .features       = NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT | NFT_SET_TIMEOUT,
 572         .ops            = {
 573                 .privsize       = nft_rbtree_privsize,
 574                 .elemsize       = offsetof(struct nft_rbtree_elem, ext),
 575                 .estimate       = nft_rbtree_estimate,
 576                 .init           = nft_rbtree_init,
 577                 .destroy        = nft_rbtree_destroy,
 578                 .insert         = nft_rbtree_insert,
 579                 .remove         = nft_rbtree_remove,
 580                 .deactivate     = nft_rbtree_deactivate,
 581                 .flush          = nft_rbtree_flush,
 582                 .activate       = nft_rbtree_activate,
 583                 .lookup         = nft_rbtree_lookup,
 584                 .walk           = nft_rbtree_walk,
 585                 .get            = nft_rbtree_get,
 586         },
 587 };