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Linux/net/netfilter/nft_hash.c

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

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