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/rhashtable.h>
  19 #include <linux/netfilter.h>
  20 #include <linux/netfilter/nf_tables.h>
  21 #include <net/netfilter/nf_tables.h>
  22
  23 /* We target a hash table size of 4, element hint is 75% of final size */
  24 #define NFT_HASH_ELEMENT_HINT 3
  25
  26 struct nft_hash {
  27         struct rhashtable               ht;
  28 };
  29
  30 struct nft_hash_elem {
  31         struct rhash_head               node;
  32         struct nft_set_ext              ext;
  33 };
  34
  35 struct nft_hash_cmp_arg {
  36         const struct nft_set            *set;
  37         const struct nft_data           *key;
  38         u8                              genmask;
  39 };
  40
  41 static const struct rhashtable_params nft_hash_params;
  42
  43 static inline u32 nft_hash_key(const void *data, u32 len, u32 seed)
  44 {
  45         const struct nft_hash_cmp_arg *arg = data;
  46
  47         return jhash(arg->key, len, seed);
  48 }
  49
  50 static inline u32 nft_hash_obj(const void *data, u32 len, u32 seed)
  51 {
  52         const struct nft_hash_elem *he = data;
  53
  54         return jhash(nft_set_ext_key(&he->ext), len, seed);
  55 }
  56
  57 static inline int nft_hash_cmp(struct rhashtable_compare_arg *arg,
  58                                const void *ptr)
  59 {
  60         const struct nft_hash_cmp_arg *x = arg->key;
  61         const struct nft_hash_elem *he = ptr;
  62
  63         if (nft_data_cmp(nft_set_ext_key(&he->ext), x->key, x->set->klen))
  64                 return 1;
  65         if (!nft_set_elem_active(&he->ext, x->genmask))
  66                 return 1;
  67         return 0;
  68 }
  69
  70 static bool nft_hash_lookup(const struct nft_set *set,
  71                             const struct nft_data *key,
  72                             const struct nft_set_ext **ext)
  73 {
  74         struct nft_hash *priv = nft_set_priv(set);
  75         const struct nft_hash_elem *he;
  76         struct nft_hash_cmp_arg arg = {
  77                 .genmask = nft_genmask_cur(read_pnet(&set->pnet)),
  78                 .set     = set,
  79                 .key     = key,
  80         };
  81
  82         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
  83         if (he != NULL)
  84                 *ext = &he->ext;
  85
  86         return !!he;
  87 }
  88
  89 static int nft_hash_insert(const struct nft_set *set,
  90                            const struct nft_set_elem *elem)
  91 {
  92         struct nft_hash *priv = nft_set_priv(set);
  93         struct nft_hash_elem *he = elem->priv;
  94         struct nft_hash_cmp_arg arg = {
  95                 .genmask = nft_genmask_next(read_pnet(&set->pnet)),
  96                 .set     = set,
  97                 .key     = &elem->key,
  98         };
  99
 100         return rhashtable_lookup_insert_key(&priv->ht, &arg, &he->node,
 101                                             nft_hash_params);
 102 }
 103
 104 static void nft_hash_activate(const struct nft_set *set,
 105                               const struct nft_set_elem *elem)
 106 {
 107         struct nft_hash_elem *he = elem->priv;
 108
 109         nft_set_elem_change_active(set, &he->ext);
 110 }
 111
 112 static void *nft_hash_deactivate(const struct nft_set *set,
 113                                  const struct nft_set_elem *elem)
 114 {
 115         struct nft_hash *priv = nft_set_priv(set);
 116         struct nft_hash_elem *he;
 117         struct nft_hash_cmp_arg arg = {
 118                 .genmask = nft_genmask_next(read_pnet(&set->pnet)),
 119                 .set     = set,
 120                 .key     = &elem->key,
 121         };
 122
 123         he = rhashtable_lookup_fast(&priv->ht, &arg, nft_hash_params);
 124         if (he != NULL)
 125                 nft_set_elem_change_active(set, &he->ext);
 126
 127         return he;
 128 }
 129
 130 static void nft_hash_remove(const struct nft_set *set,
 131                             const struct nft_set_elem *elem)
 132 {
 133         struct nft_hash *priv = nft_set_priv(set);
 134         struct nft_hash_elem *he = elem->priv;
 135
 136         rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params);
 137 }
 138
 139 static void nft_hash_walk(const struct nft_ctx *ctx, const struct nft_set *set,
 140                           struct nft_set_iter *iter)
 141 {
 142         struct nft_hash *priv = nft_set_priv(set);
 143         struct nft_hash_elem *he;
 144         struct rhashtable_iter hti;
 145         struct nft_set_elem elem;
 146         u8 genmask = nft_genmask_cur(read_pnet(&set->pnet));
 147         int err;
 148
 149         err = rhashtable_walk_init(&priv->ht, &hti);
 150         iter->err = err;
 151         if (err)
 152                 return;
 153
 154         err = rhashtable_walk_start(&hti);
 155         if (err && err != -EAGAIN) {
 156                 iter->err = err;
 157                 goto out;
 158         }
 159
 160         while ((he = rhashtable_walk_next(&hti))) {
 161                 if (IS_ERR(he)) {
 162                         err = PTR_ERR(he);
 163                         if (err != -EAGAIN) {
 164                                 iter->err = err;
 165                                 goto out;
 166                         }
 167
 168                         continue;
 169                 }
 170
 171                 if (iter->count < iter->skip)
 172                         goto cont;
 173                 if (!nft_set_elem_active(&he->ext, genmask))
 174                         goto cont;
 175
 176                 elem.priv = he;
 177
 178                 iter->err = iter->fn(ctx, set, iter, &elem);
 179                 if (iter->err < 0)
 180                         goto out;
 181
 182 cont:
 183                 iter->count++;
 184         }
 185
 186 out:
 187         rhashtable_walk_stop(&hti);
 188         rhashtable_walk_exit(&hti);
 189 }
 190
 191 static unsigned int nft_hash_privsize(const struct nlattr * const nla[])
 192 {
 193         return sizeof(struct nft_hash);
 194 }
 195
 196 static const struct rhashtable_params nft_hash_params = {
 197         .head_offset            = offsetof(struct nft_hash_elem, node),
 198         .hashfn                 = nft_hash_key,
 199         .obj_hashfn             = nft_hash_obj,
 200         .obj_cmpfn              = nft_hash_cmp,
 201         .automatic_shrinking    = true,
 202 };
 203
 204 static int nft_hash_init(const struct nft_set *set,
 205                          const struct nft_set_desc *desc,
 206                          const struct nlattr * const tb[])
 207 {
 208         struct nft_hash *priv = nft_set_priv(set);
 209         struct rhashtable_params params = nft_hash_params;
 210
 211         params.nelem_hint = desc->size ?: NFT_HASH_ELEMENT_HINT;
 212         params.key_len    = set->klen;
 213
 214         return rhashtable_init(&priv->ht, &params);
 215 }
 216
 217 static void nft_hash_elem_destroy(void *ptr, void *arg)
 218 {
 219         nft_set_elem_destroy((const struct nft_set *)arg, ptr);
 220 }
 221
 222 static void nft_hash_destroy(const struct nft_set *set)
 223 {
 224         struct nft_hash *priv = nft_set_priv(set);
 225
 226         rhashtable_free_and_destroy(&priv->ht, nft_hash_elem_destroy,
 227                                     (void *)set);
 228 }
 229
 230 static bool nft_hash_estimate(const struct nft_set_desc *desc, u32 features,
 231                               struct nft_set_estimate *est)
 232 {
 233         unsigned int esize;
 234
 235         esize = sizeof(struct nft_hash_elem);
 236         if (desc->size) {
 237                 est->size = sizeof(struct nft_hash) +
 238                             roundup_pow_of_two(desc->size * 4 / 3) *
 239                             sizeof(struct nft_hash_elem *) +
 240                             desc->size * esize;
 241         } else {
 242                 /* Resizing happens when the load drops below 30% or goes
 243                  * above 75%. The average of 52.5% load (approximated by 50%)
 244                  * is used for the size estimation of the hash buckets,
 245                  * meaning we calculate two buckets per element.
 246                  */
 247                 est->size = esize + 2 * sizeof(struct nft_hash_elem *);
 248         }
 249
 250         est->class = NFT_SET_CLASS_O_1;
 251
 252         return true;
 253 }
 254
 255 static struct nft_set_ops nft_hash_ops __read_mostly = {
 256         .privsize       = nft_hash_privsize,
 257         .elemsize       = offsetof(struct nft_hash_elem, ext),
 258         .estimate       = nft_hash_estimate,
 259         .init           = nft_hash_init,
 260         .destroy        = nft_hash_destroy,
 261         .insert         = nft_hash_insert,
 262         .activate       = nft_hash_activate,
 263         .deactivate     = nft_hash_deactivate,
 264         .remove         = nft_hash_remove,
 265         .lookup         = nft_hash_lookup,
 266         .walk           = nft_hash_walk,
 267         .features       = NFT_SET_MAP,
 268         .owner          = THIS_MODULE,
 269 };
 270
 271 static int __init nft_hash_module_init(void)
 272 {
 273         return nft_register_set(&nft_hash_ops);
 274 }
 275
 276 static void __exit nft_hash_module_exit(void)
 277 {
 278         nft_unregister_set(&nft_hash_ops);
 279 }
 280
 281 module_init(nft_hash_module_init);
 282 module_exit(nft_hash_module_exit);
 283
 284 MODULE_LICENSE("GPL");
 285 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 286 MODULE_ALIAS_NFT_SET();