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
27struct nft_hash {
28	struct rhashtable		ht;
29	struct delayed_work		gc_work;
30};
31
32struct nft_hash_elem {
33	struct rhash_head		node;
34	struct nft_set_ext		ext;
35};
36
37struct nft_hash_cmp_arg {
38	const struct nft_set		*set;
39	const u32			*key;
40	u8				genmask;
41};
42
43static const struct rhashtable_params nft_hash_params;
44
45static 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
52static 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
59static 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
74static 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
92static 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;
118out:
119	*ext = &he->ext;
120	return true;
121
122err2:
123	nft_set_elem_destroy(set, he);
124err1:
125	return false;
126}
127
128static 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
143static 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
152static 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
176static 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
185static 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);
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
230cont:
231		iter->count++;
232	}
233
234out:
235	rhashtable_walk_stop(&hti);
236	rhashtable_walk_exit(&hti);
237}
238
239static 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);
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	}
278out:
279	rhashtable_walk_stop(&hti);
280	rhashtable_walk_exit(&hti);
281
282	nft_set_gc_batch_complete(gcb);
283schedule:
284	queue_delayed_work(system_power_efficient_wq, &priv->gc_work,
285			   nft_set_gc_interval(set));
286}
287
288static unsigned int nft_hash_privsize(const struct nlattr * const nla[])
289{
290	return sizeof(struct nft_hash);
291}
292
293static 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
301static 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
323static void nft_hash_elem_destroy(void *ptr, void *arg)
324{
325	nft_set_elem_destroy((const struct nft_set *)arg, ptr);
326}
327
328static 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
337static 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
362static 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
379static int __init nft_hash_module_init(void)
380{
381	return nft_register_set(&nft_hash_ops);
382}
383
384static void __exit nft_hash_module_exit(void)
385{
386	nft_unregister_set(&nft_hash_ops);
387}
388
389module_init(nft_hash_module_init);
390module_exit(nft_hash_module_exit);
391
392MODULE_LICENSE("GPL");
393MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
394MODULE_ALIAS_NFT_SET();
395