1/*
2 * (C) 2007 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#include <linux/module.h>
9#include <linux/skbuff.h>
10#include <linux/gen_stats.h>
11#include <linux/jhash.h>
12#include <linux/rtnetlink.h>
13#include <linux/random.h>
14#include <linux/slab.h>
15#include <net/gen_stats.h>
16#include <net/netlink.h>
17
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter/xt_RATEEST.h>
20#include <net/netfilter/xt_rateest.h>
21
22static DEFINE_MUTEX(xt_rateest_mutex);
23
24#define RATEEST_HSIZE	16
25static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
26static unsigned int jhash_rnd __read_mostly;
27static bool rnd_inited __read_mostly;
28
29static unsigned int xt_rateest_hash(const char *name)
30{
31	return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) &
32	       (RATEEST_HSIZE - 1);
33}
34
35static void xt_rateest_hash_insert(struct xt_rateest *est)
36{
37	unsigned int h;
38
39	h = xt_rateest_hash(est->name);
40	hlist_add_head(&est->list, &rateest_hash[h]);
41}
42
43struct xt_rateest *xt_rateest_lookup(const char *name)
44{
45	struct xt_rateest *est;
46	unsigned int h;
47
48	h = xt_rateest_hash(name);
49	mutex_lock(&xt_rateest_mutex);
50	hlist_for_each_entry(est, &rateest_hash[h], list) {
51		if (strcmp(est->name, name) == 0) {
52			est->refcnt++;
53			mutex_unlock(&xt_rateest_mutex);
54			return est;
55		}
56	}
57	mutex_unlock(&xt_rateest_mutex);
58	return NULL;
59}
60EXPORT_SYMBOL_GPL(xt_rateest_lookup);
61
62void xt_rateest_put(struct xt_rateest *est)
63{
64	mutex_lock(&xt_rateest_mutex);
65	if (--est->refcnt == 0) {
66		hlist_del(&est->list);
67		gen_kill_estimator(&est->bstats, &est->rstats);
68		/*
69		 * gen_estimator est_timer() might access est->lock or bstats,
70		 * wait a RCU grace period before freeing 'est'
71		 */
72		kfree_rcu(est, rcu);
73	}
74	mutex_unlock(&xt_rateest_mutex);
75}
76EXPORT_SYMBOL_GPL(xt_rateest_put);
77
78static unsigned int
79xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
80{
81	const struct xt_rateest_target_info *info = par->targinfo;
82	struct gnet_stats_basic_packed *stats = &info->est->bstats;
83
84	spin_lock_bh(&info->est->lock);
85	stats->bytes += skb->len;
86	stats->packets++;
87	spin_unlock_bh(&info->est->lock);
88
89	return XT_CONTINUE;
90}
91
92static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
93{
94	struct xt_rateest_target_info *info = par->targinfo;
95	struct xt_rateest *est;
96	struct {
97		struct nlattr		opt;
98		struct gnet_estimator	est;
99	} cfg;
100	int ret;
101
102	if (unlikely(!rnd_inited)) {
103		get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
104		rnd_inited = true;
105	}
106
107	est = xt_rateest_lookup(info->name);
108	if (est) {
109		/*
110		 * If estimator parameters are specified, they must match the
111		 * existing estimator.
112		 */
113		if ((!info->interval && !info->ewma_log) ||
114		    (info->interval != est->params.interval ||
115		     info->ewma_log != est->params.ewma_log)) {
116			xt_rateest_put(est);
117			return -EINVAL;
118		}
119		info->est = est;
120		return 0;
121	}
122
123	ret = -ENOMEM;
124	est = kzalloc(sizeof(*est), GFP_KERNEL);
125	if (!est)
126		goto err1;
127
128	strlcpy(est->name, info->name, sizeof(est->name));
129	spin_lock_init(&est->lock);
130	est->refcnt		= 1;
131	est->params.interval	= info->interval;
132	est->params.ewma_log	= info->ewma_log;
133
134	cfg.opt.nla_len		= nla_attr_size(sizeof(cfg.est));
135	cfg.opt.nla_type	= TCA_STATS_RATE_EST;
136	cfg.est.interval	= info->interval;
137	cfg.est.ewma_log	= info->ewma_log;
138
139	ret = gen_new_estimator(&est->bstats, NULL, &est->rstats,
140				&est->lock, &cfg.opt);
141	if (ret < 0)
142		goto err2;
143
144	info->est = est;
145	xt_rateest_hash_insert(est);
146	return 0;
147
148err2:
149	kfree(est);
150err1:
151	return ret;
152}
153
154static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
155{
156	struct xt_rateest_target_info *info = par->targinfo;
157
158	xt_rateest_put(info->est);
159}
160
161static struct xt_target xt_rateest_tg_reg __read_mostly = {
162	.name       = "RATEEST",
163	.revision   = 0,
164	.family     = NFPROTO_UNSPEC,
165	.target     = xt_rateest_tg,
166	.checkentry = xt_rateest_tg_checkentry,
167	.destroy    = xt_rateest_tg_destroy,
168	.targetsize = sizeof(struct xt_rateest_target_info),
169	.me         = THIS_MODULE,
170};
171
172static int __init xt_rateest_tg_init(void)
173{
174	unsigned int i;
175
176	for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
177		INIT_HLIST_HEAD(&rateest_hash[i]);
178
179	return xt_register_target(&xt_rateest_tg_reg);
180}
181
182static void __exit xt_rateest_tg_fini(void)
183{
184	xt_unregister_target(&xt_rateest_tg_reg);
185}
186
187
188MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
189MODULE_LICENSE("GPL");
190MODULE_DESCRIPTION("Xtables: packet rate estimator");
191MODULE_ALIAS("ipt_RATEEST");
192MODULE_ALIAS("ip6t_RATEEST");
193module_init(xt_rateest_tg_init);
194module_exit(xt_rateest_tg_fini);
195