net/netfilter/nft_hash.c

   1 /*
   2  * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/list.h>
  15 #include <linux/log2.h>
  16 #include <linux/jhash.h>
  17 #include <linux/netlink.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/rhashtable.h>
  20 #include <linux/netfilter.h>
  21 #include <linux/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_tables.h>
  23
  24 /* We target a hash table size of 4, element hint is 75% of final size */
  25 #define NFT_HASH_ELEMENT_HINT 3
  26
  27 struct nft_hash {
  28         struct rhashtable               ht;
  29         struct delayed_work             gc_work;
  30 };
  31
  32 struct nft_hash_elem {
  33         struct rhash_head               node;
  34         struct nft_set_ext              ext;
  35 };
  36
  37 struct nft_hash_cmp_arg {
  38         const struct nft_set            *set;
  39         const u32                       *key;
  40         u8                              genmask;
  41 };
  42
  43 static const struct rhashtable_params nft_hash_params;
  44
  45 static inline u32 nft_hash_key(const void *data, u32 len, u32 seed)
  46 {
  47         const struct nft_hash_cmp_arg *arg = data;
  48
  49         return jhash(arg->key, len, seed);
  50 }
  51
  52 static inline u32 nft_hash_obj(const void *data, u32 len, u32 seed)
  53 {
  54         const struct nft_hash_elem *he = data;
  55
  56         return jhash(nft_set_ext_key(&he->ext), len, seed);
  57 }
  58
  59 static inline int nft_hash_cmp(struct rhashtable_compare_arg *arg,
  60                                const void *ptr)
  61 {
  62         const struct nft_hash_cmp_arg *x = arg->key;
  63         const struct nft_hash_elem *he = ptr;
  64
  65         if (memcmp(nft_set_ext_key(&he->ext), x->key, x->set->klen))
  66                 return 1;
  67         if (nft_set_elem_expired(&he->ext))
  68                 return 1;
  69         if (!nft_set_elem_active(&he->ext, x->genmask))
  70                 return 1;
  71         return 0;
  72 }
  73
  74 static bool nft_hash_lookup(const struct nft_set *set, const u32 *key,
  75                             const struct nft_set_ext **ext)
  76 {
  77         struct nft_hash *priv = nft_set_priv(set);
  78         const struct nft_hash_elem *he;
  79         struct nft_hash_cmp_arg arg = {
  80                 .genmask = nft_genmask_cur(read_pnet(&set->pnet)),
  81                 .set     = set,
  82                 .key     = key,
  83         };
  84
  85         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
  86         if (he != NULL)
  87                 *ext = &he->ext;
  88
  89         return !!he;
  90 }
  91
  92 static bool nft_hash_update(struct nft_set *set, const u32 *key,
  93                             void *(*new)(struct nft_set *,
  94                                          const struct nft_expr *,
  95                                          struct nft_regs *regs),
  96                             const struct nft_expr *expr,
  97                             struct nft_regs *regs,
  98                             const struct nft_set_ext **ext)
  99 {
 100         struct nft_hash *priv = nft_set_priv(set);
 101         struct nft_hash_elem *he;
 102         struct nft_hash_cmp_arg arg = {
 103                 .genmask = NFT_GENMASK_ANY,
 104                 .set     = set,
 105                 .key     = key,
 106         };
 107
 108         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
 109         if (he != NULL)
 110                 goto out;
 111
 112         he = new(set, expr, regs);
 113         if (he == NULL)
 114                 goto err1;
 115         if (rhashtable_lookup_insert_key(&priv->ht, &arg, &he->node,
 116                                          nft_hash_params))
 117                 goto err2;
 118 out:
 119         *ext = &he->ext;
 120         return true;
 121
 122 err2:
 123         nft_set_elem_destroy(set, he);
 124 err1:
 125         return false;
 126 }
 127
 128 static int nft_hash_insert(const struct nft_set *set,
 129                            const struct nft_set_elem *elem)
 130 {
 131         struct nft_hash *priv = nft_set_priv(set);
 132         struct nft_hash_elem *he = elem->priv;
 133         struct nft_hash_cmp_arg arg = {
 134                 .genmask = nft_genmask_next(read_pnet(&set->pnet)),
 135                 .set     = set,
 136                 .key     = elem->key.val.data,
 137         };
 138
 139         return rhashtable_lookup_insert_key(&priv->ht, &arg, &he->node,
 140                                             nft_hash_params);
 141 }
 142
 143 static void nft_hash_activate(const struct nft_set *set,
 144                               const struct nft_set_elem *elem)
 145 {
 146         struct nft_hash_elem *he = elem->priv;
 147
 148         nft_set_elem_change_active(set, &he->ext);
 149         nft_set_elem_clear_busy(&he->ext);
 150 }
 151
 152 static void *nft_hash_deactivate(const struct nft_set *set,
 153                                  const struct nft_set_elem *elem)
 154 {
 155         struct nft_hash *priv = nft_set_priv(set);
 156         struct nft_hash_elem *he;
 157         struct nft_hash_cmp_arg arg = {
 158                 .genmask = nft_genmask_next(read_pnet(&set->pnet)),
 159                 .set     = set,
 160                 .key     = elem->key.val.data,
 161         };
 162
 163         rcu_read_lock();
 164         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
 165         if (he != NULL) {
 166                 if (!nft_set_elem_mark_busy(&he->ext))
 167                         nft_set_elem_change_active(set, &he->ext);
 168                 else
 169                         he = NULL;
 170         }
 171         rcu_read_unlock();
 172
 173         return he;
 174 }
 175
 176 static void nft_hash_remove(const struct nft_set *set,
 177                             const struct nft_set_elem *elem)
 178 {
 179         struct nft_hash *priv = nft_set_priv(set);
 180         struct nft_hash_elem *he = elem->priv;
 181
 182         rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params);
 183 }
 184
 185 static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set,
 186                           struct nft_set_iter *iter)
 187 {
 188         struct nft_hash *priv = nft_set_priv(set);
 189         struct nft_hash_elem *he;
 190         struct rhashtable_iter hti;
 191         struct nft_set_elem elem;
 192         u8 genmask = nft_genmask_cur(read_pnet(&set->pnet));
 193         int err;
 194
 195         err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 196         iter->err = err;
 197         if (err)
 198                 return;
 199
 200         err = rhashtable_walk_start(&hti);
 201         if (err && err != -EAGAIN) {
 202                 iter->err = err;
 203                 goto out;
 204         }
 205
 206         while ((he = rhashtable_walk_next(&hti))) {
 207                 if (IS_ERR(he)) {
 208                         err = PTR_ERR(he);
 209                         if (err != -EAGAIN) {
 210                                 iter->err = err;
 211                                 goto out;
 212                         }
 213
 214                         continue;
 215                 }
 216
 217                 if (iter->count < iter->skip)
 218                         goto cont;
 219                 if (nft_set_elem_expired(&he->ext))
 220                         goto cont;
 221                 if (!nft_set_elem_active(&he->ext, genmask))
 222                         goto cont;
 223
 224                 elem.priv = he;
 225
 226                 iter->err = iter->fn(ctx, set, iter, &elem);
 227                 if (iter->err < 0)
 228                         goto out;
 229
 230 cont:
 231                 iter->count++;
 232         }
 233
 234 out:
 235         rhashtable_walk_stop(&hti);
 236         rhashtable_walk_exit(&hti);
 237 }
 238
 239 static void nft_hash_gc(struct work_struct *work)
 240 {
 241         struct nft_set *set;
 242         struct nft_hash_elem *he;
 243         struct nft_hash *priv;
 244         struct nft_set_gc_batch *gcb = NULL;
 245         struct rhashtable_iter hti;
 246         int err;
 247
 248         priv = container_of(work, struct nft_hash, gc_work.work);
 249         set  = nft_set_container_of(priv);
 250
 251         err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 252         if (err)
 253                 goto schedule;
 254
 255         err = rhashtable_walk_start(&hti);
 256         if (err && err != -EAGAIN)
 257                 goto out;
 258
 259         while ((he = rhashtable_walk_next(&hti))) {
 260                 if (IS_ERR(he)) {
 261                         if (PTR_ERR(he) != -EAGAIN)
 262                                 goto out;
 263                         continue;
 264                 }
 265
 266                 if (!nft_set_elem_expired(&he->ext))
 267                         continue;
 268                 if (nft_set_elem_mark_busy(&he->ext))
 269                         continue;
 270
 271                 gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
 272                 if (gcb == NULL)
 273                         goto out;
 274                 rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params);
 275                 atomic_dec(&set->nelems);
 276                 nft_set_gc_batch_add(gcb, he);
 277         }
 278 out:
 279         rhashtable_walk_stop(&hti);
 280         rhashtable_walk_exit(&hti);
 281
 282         nft_set_gc_batch_complete(gcb);
 283 schedule:
 284         queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 285                            nft_set_gc_interval(set));
 286 }
 287
 288 static unsigned int nft_hash_privsize(const struct nlattr * const nla[])
 289 {
 290         return sizeof(struct nft_hash);
 291 }
 292
 293 static const struct rhashtable_params nft_hash_params = {
 294         .head_offset            = offsetof(struct nft_hash_elem, node),
 295         .hashfn                 = nft_hash_key,
 296         .obj_hashfn             = nft_hash_obj,
 297         .obj_cmpfn              = nft_hash_cmp,
 298         .automatic_shrinking    = true,
 299 };
 300
 301 static int nft_hash_init(const struct nft_set *set,
 302                          const struct nft_set_desc *desc,
 303                          const struct nlattr * const tb[])
 304 {
 305         struct nft_hash *priv = nft_set_priv(set);
 306         struct rhashtable_params params = nft_hash_params;
 307         int err;
 308
 309         params.nelem_hint = desc->size ?: NFT_HASH_ELEMENT_HINT;
 310         params.key_len    = set->klen;
 311
 312         err = rhashtable_init(&priv->ht, &params);
 313         if (err < 0)
 314                 return err;
 315
 316         INIT_DEFERRABLE_WORK(&priv->gc_work, nft_hash_gc);
 317         if (set->flags & NFT_SET_TIMEOUT)
 318                 queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 319                                    nft_set_gc_interval(set));
 320         return 0;
 321 }
 322
 323 static void nft_hash_elem_destroy(void *ptr, void *arg)
 324 {
 325         nft_set_elem_destroy((const struct nft_set *)arg, ptr);
 326 }
 327
 328 static void nft_hash_destroy(const struct nft_set *set)
 329 {
 330         struct nft_hash *priv = nft_set_priv(set);
 331
 332         cancel_delayed_work_sync(&priv->gc_work);
 333         rhashtable_free_and_destroy(&priv->ht, nft_hash_elem_destroy,
 334                                     (void *)set);
 335 }
 336
 337 static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
 338                               struct nft_set_estimate *est)
 339 {
 340         unsigned int esize;
 341
 342         esize = sizeof(struct nft_hash_elem);
 343         if (desc->size) {
 344                 est->size = sizeof(struct nft_hash) +
 345                             roundup_pow_of_two(desc->size * 4 / 3) *
 346                             sizeof(struct nft_hash_elem *) +
 347                             desc->size * esize;
 348         } else {
 349                 /* Resizing happens when the load drops below 30% or goes
 350                  * above 75%. The average of 52.5% load (approximated by 50%)
 351                  * is used for the size estimation of the hash buckets,
 352                  * meaning we calculate two buckets per element.
 353                  */
 354                 est->size = esize + 2 * sizeof(struct nft_hash_elem *);
 355         }
 356
 357         est->class = NFT_SET_CLASS_O_1;
 358
 359         return true;
 360 }
 361
 362 static struct nft_set_ops nft_hash_ops __read_mostly = {
 363         .privsize       = nft_hash_privsize,
 364         .elemsize       = offsetof(struct nft_hash_elem, ext),
 365         .estimate       = nft_hash_estimate,
 366         .init           = nft_hash_init,
 367         .destroy        = nft_hash_destroy,
 368         .insert         = nft_hash_insert,
 369         .activate       = nft_hash_activate,
 370         .deactivate     = nft_hash_deactivate,
 371         .remove         = nft_hash_remove,
 372         .lookup         = nft_hash_lookup,
 373         .update         = nft_hash_update,
 374         .walk           = nft_hash_walk,
 375         .features       = NFT_SET_MAP | NFT_SET_TIMEOUT,
 376         .owner          = THIS_MODULE,
 377 };
 378
 379 static int __init nft_hash_module_init(void)
 380 {
 381         return nft_register_set(&nft_hash_ops);
 382 }
 383
 384 static void __exit nft_hash_module_exit(void)
 385 {
 386         nft_unregister_set(&nft_hash_ops);
 387 }
 388
 389 module_init(nft_hash_module_init);
 390 module_exit(nft_hash_module_exit);
 391
 392 MODULE_LICENSE("GPL");
 393 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 394 MODULE_ALIAS_NFT_SET();