net/netfilter/nft_set_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 net *net, const struct nft_set *set,
  75                             const u32 *key, 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(net),
  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, *prev;
 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
 116         prev = rhashtable_lookup_get_insert_key(&priv->ht, &arg, &he->node,
 117                                                 nft_hash_params);
 118         if (IS_ERR(prev))
 119                 goto err2;
 120
 121         /* Another cpu may race to insert the element with the same key */
 122         if (prev) {
 123                 nft_set_elem_destroy(set, he, true);
 124                 he = prev;
 125         }
 126
 127 out:
 128         *ext = &he->ext;
 129         return true;
 130
 131 err2:
 132         nft_set_elem_destroy(set, he, true);
 133 err1:
 134         return false;
 135 }
 136
 137 static int nft_hash_insert(const struct net *net, const struct nft_set *set,
 138                            const struct nft_set_elem *elem,
 139                            struct nft_set_ext **ext)
 140 {
 141         struct nft_hash *priv = nft_set_priv(set);
 142         struct nft_hash_elem *he = elem->priv;
 143         struct nft_hash_cmp_arg arg = {
 144                 .genmask = nft_genmask_next(net),
 145                 .set     = set,
 146                 .key     = elem->key.val.data,
 147         };
 148         struct nft_hash_elem *prev;
 149
 150         prev = rhashtable_lookup_get_insert_key(&priv->ht, &arg, &he->node,
 151                                                nft_hash_params);
 152         if (IS_ERR(prev))
 153                 return PTR_ERR(prev);
 154         if (prev) {
 155                 *ext = &prev->ext;
 156                 return -EEXIST;
 157         }
 158         return 0;
 159 }
 160
 161 static void nft_hash_activate(const struct net *net, const struct nft_set *set,
 162                               const struct nft_set_elem *elem)
 163 {
 164         struct nft_hash_elem *he = elem->priv;
 165
 166         nft_set_elem_change_active(net, set, &he->ext);
 167         nft_set_elem_clear_busy(&he->ext);
 168 }
 169
 170 static void *nft_hash_deactivate(const struct net *net,
 171                                  const struct nft_set *set,
 172                                  const struct nft_set_elem *elem)
 173 {
 174         struct nft_hash *priv = nft_set_priv(set);
 175         struct nft_hash_elem *he;
 176         struct nft_hash_cmp_arg arg = {
 177                 .genmask = nft_genmask_next(net),
 178                 .set     = set,
 179                 .key     = elem->key.val.data,
 180         };
 181
 182         rcu_read_lock();
 183         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
 184         if (he != NULL) {
 185                 if (!nft_set_elem_mark_busy(&he->ext) ||
 186                     !nft_is_active(net, &he->ext))
 187                         nft_set_elem_change_active(net, set, &he->ext);
 188                 else
 189                         he = NULL;
 190         }
 191         rcu_read_unlock();
 192
 193         return he;
 194 }
 195
 196 static void nft_hash_remove(const struct nft_set *set,
 197                             const struct nft_set_elem *elem)
 198 {
 199         struct nft_hash *priv = nft_set_priv(set);
 200         struct nft_hash_elem *he = elem->priv;
 201
 202         rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params);
 203 }
 204
 205 static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set,
 206                           struct nft_set_iter *iter)
 207 {
 208         struct nft_hash *priv = nft_set_priv(set);
 209         struct nft_hash_elem *he;
 210         struct rhashtable_iter hti;
 211         struct nft_set_elem elem;
 212         int err;
 213
 214         err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 215         iter->err = err;
 216         if (err)
 217                 return;
 218
 219         err = rhashtable_walk_start(&hti);
 220         if (err && err != -EAGAIN) {
 221                 iter->err = err;
 222                 goto out;
 223         }
 224
 225         while ((he = rhashtable_walk_next(&hti))) {
 226                 if (IS_ERR(he)) {
 227                         err = PTR_ERR(he);
 228                         if (err != -EAGAIN) {
 229                                 iter->err = err;
 230                                 goto out;
 231                         }
 232
 233                         continue;
 234                 }
 235
 236                 if (iter->count < iter->skip)
 237                         goto cont;
 238                 if (nft_set_elem_expired(&he->ext))
 239                         goto cont;
 240                 if (!nft_set_elem_active(&he->ext, iter->genmask))
 241                         goto cont;
 242
 243                 elem.priv = he;
 244
 245                 iter->err = iter->fn(ctx, set, iter, &elem);
 246                 if (iter->err < 0)
 247                         goto out;
 248
 249 cont:
 250                 iter->count++;
 251         }
 252
 253 out:
 254         rhashtable_walk_stop(&hti);
 255         rhashtable_walk_exit(&hti);
 256 }
 257
 258 static void nft_hash_gc(struct work_struct *work)
 259 {
 260         struct nft_set *set;
 261         struct nft_hash_elem *he;
 262         struct nft_hash *priv;
 263         struct nft_set_gc_batch *gcb = NULL;
 264         struct rhashtable_iter hti;
 265         int err;
 266
 267         priv = container_of(work, struct nft_hash, gc_work.work);
 268         set  = nft_set_container_of(priv);
 269
 270         err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL);
 271         if (err)
 272                 goto schedule;
 273
 274         err = rhashtable_walk_start(&hti);
 275         if (err && err != -EAGAIN)
 276                 goto out;
 277
 278         while ((he = rhashtable_walk_next(&hti))) {
 279                 if (IS_ERR(he)) {
 280                         if (PTR_ERR(he) != -EAGAIN)
 281                                 goto out;
 282                         continue;
 283                 }
 284
 285                 if (!nft_set_elem_expired(&he->ext))
 286                         continue;
 287                 if (nft_set_elem_mark_busy(&he->ext))
 288                         continue;
 289
 290                 gcb = nft_set_gc_batch_check(set, gcb, GFP_ATOMIC);
 291                 if (gcb == NULL)
 292                         goto out;
 293                 rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params);
 294                 atomic_dec(&set->nelems);
 295                 nft_set_gc_batch_add(gcb, he);
 296         }
 297 out:
 298         rhashtable_walk_stop(&hti);
 299         rhashtable_walk_exit(&hti);
 300
 301         nft_set_gc_batch_complete(gcb);
 302 schedule:
 303         queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 304                            nft_set_gc_interval(set));
 305 }
 306
 307 static unsigned int nft_hash_privsize(const struct nlattr * const nla[])
 308 {
 309         return sizeof(struct nft_hash);
 310 }
 311
 312 static const struct rhashtable_params nft_hash_params = {
 313         .head_offset            = offsetof(struct nft_hash_elem, node),
 314         .hashfn                 = nft_hash_key,
 315         .obj_hashfn             = nft_hash_obj,
 316         .obj_cmpfn              = nft_hash_cmp,
 317         .automatic_shrinking    = true,
 318 };
 319
 320 static int nft_hash_init(const struct nft_set *set,
 321                          const struct nft_set_desc *desc,
 322                          const struct nlattr * const tb[])
 323 {
 324         struct nft_hash *priv = nft_set_priv(set);
 325         struct rhashtable_params params = nft_hash_params;
 326         int err;
 327
 328         params.nelem_hint = desc->size ?: NFT_HASH_ELEMENT_HINT;
 329         params.key_len    = set->klen;
 330
 331         err = rhashtable_init(&priv->ht, &params);
 332         if (err < 0)
 333                 return err;
 334
 335         INIT_DEFERRABLE_WORK(&priv->gc_work, nft_hash_gc);
 336         if (set->flags & NFT_SET_TIMEOUT)
 337                 queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
 338                                    nft_set_gc_interval(set));
 339         return 0;
 340 }
 341
 342 static void nft_hash_elem_destroy(void *ptr, void *arg)
 343 {
 344         nft_set_elem_destroy((const struct nft_set *)arg, ptr, true);
 345 }
 346
 347 static void nft_hash_destroy(const struct nft_set *set)
 348 {
 349         struct nft_hash *priv = nft_set_priv(set);
 350
 351         cancel_delayed_work_sync(&priv->gc_work);
 352         rhashtable_free_and_destroy(&priv->ht, nft_hash_elem_destroy,
 353                                     (void *)set);
 354 }
 355
 356 static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
 357                               struct nft_set_estimate *est)
 358 {
 359         unsigned int esize;
 360
 361         esize = sizeof(struct nft_hash_elem);
 362         if (desc->size) {
 363                 est->size = sizeof(struct nft_hash) +
 364                             roundup_pow_of_two(desc->size * 4 / 3) *
 365                             sizeof(struct nft_hash_elem *) +
 366                             desc->size * esize;
 367         } else {
 368                 /* Resizing happens when the load drops below 30% or goes
 369                  * above 75%. The average of 52.5% load (approximated by 50%)
 370                  * is used for the size estimation of the hash buckets,
 371                  * meaning we calculate two buckets per element.
 372                  */
 373                 est->size = esize + 2 * sizeof(struct nft_hash_elem *);
 374         }
 375
 376         est->class = NFT_SET_CLASS_O_1;
 377
 378         return true;
 379 }
 380
 381 static struct nft_set_ops nft_hash_ops __read_mostly = {
 382         .privsize       = nft_hash_privsize,
 383         .elemsize       = offsetof(struct nft_hash_elem, ext),
 384         .estimate       = nft_hash_estimate,
 385         .init           = nft_hash_init,
 386         .destroy        = nft_hash_destroy,
 387         .insert         = nft_hash_insert,
 388         .activate       = nft_hash_activate,
 389         .deactivate     = nft_hash_deactivate,
 390         .remove         = nft_hash_remove,
 391         .lookup         = nft_hash_lookup,
 392         .update         = nft_hash_update,
 393         .walk           = nft_hash_walk,
 394         .features       = NFT_SET_MAP | NFT_SET_TIMEOUT,
 395         .owner          = THIS_MODULE,
 396 };
 397
 398 static int __init nft_hash_module_init(void)
 399 {
 400         return nft_register_set(&nft_hash_ops);
 401 }
 402
 403 static void __exit nft_hash_module_exit(void)
 404 {
 405         nft_unregister_set(&nft_hash_ops);
 406 }
 407
 408 module_init(nft_hash_module_init);
 409 module_exit(nft_hash_module_exit);
 410
 411 MODULE_LICENSE("GPL");
 412 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 413 MODULE_ALIAS_NFT_SET();