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
22 static DEFINE_MUTEX(xt_rateest_mutex);
23
24 #define RATEEST_HSIZE 16
25 static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
26 static unsigned int jhash_rnd __read_mostly;
27 static bool rnd_inited __read_mostly;
28
xt_rateest_hash(const char * name)29 static 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
xt_rateest_hash_insert(struct xt_rateest * est)35 static 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
xt_rateest_lookup(const char * name)43 struct xt_rateest *xt_rateest_lookup(const char *name)
44 {
45 struct xt_rateest *est;
46 struct hlist_node *n;
47 unsigned int h;
48
49 h = xt_rateest_hash(name);
50 mutex_lock(&xt_rateest_mutex);
51 hlist_for_each_entry(est, n, &rateest_hash[h], list) {
52 if (strcmp(est->name, name) == 0) {
53 est->refcnt++;
54 mutex_unlock(&xt_rateest_mutex);
55 return est;
56 }
57 }
58 mutex_unlock(&xt_rateest_mutex);
59 return NULL;
60 }
61 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
62
xt_rateest_put(struct xt_rateest * est)63 void xt_rateest_put(struct xt_rateest *est)
64 {
65 mutex_lock(&xt_rateest_mutex);
66 if (--est->refcnt == 0) {
67 hlist_del(&est->list);
68 gen_kill_estimator(&est->bstats, &est->rstats);
69 /*
70 * gen_estimator est_timer() might access est->lock or bstats,
71 * wait a RCU grace period before freeing 'est'
72 */
73 kfree_rcu(est, rcu);
74 }
75 mutex_unlock(&xt_rateest_mutex);
76 }
77 EXPORT_SYMBOL_GPL(xt_rateest_put);
78
79 static unsigned int
xt_rateest_tg(struct sk_buff * skb,const struct xt_action_param * par)80 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
81 {
82 const struct xt_rateest_target_info *info = par->targinfo;
83 struct gnet_stats_basic_packed *stats = &info->est->bstats;
84
85 spin_lock_bh(&info->est->lock);
86 stats->bytes += skb->len;
87 stats->packets++;
88 spin_unlock_bh(&info->est->lock);
89
90 return XT_CONTINUE;
91 }
92
xt_rateest_tg_checkentry(const struct xt_tgchk_param * par)93 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
94 {
95 struct xt_rateest_target_info *info = par->targinfo;
96 struct xt_rateest *est;
97 struct {
98 struct nlattr opt;
99 struct gnet_estimator est;
100 } cfg;
101 int ret;
102
103 if (unlikely(!rnd_inited)) {
104 get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
105 rnd_inited = true;
106 }
107
108 est = xt_rateest_lookup(info->name);
109 if (est) {
110 /*
111 * If estimator parameters are specified, they must match the
112 * existing estimator.
113 */
114 if ((!info->interval && !info->ewma_log) ||
115 (info->interval != est->params.interval ||
116 info->ewma_log != est->params.ewma_log)) {
117 xt_rateest_put(est);
118 return -EINVAL;
119 }
120 info->est = est;
121 return 0;
122 }
123
124 ret = -ENOMEM;
125 est = kzalloc(sizeof(*est), GFP_KERNEL);
126 if (!est)
127 goto err1;
128
129 strlcpy(est->name, info->name, sizeof(est->name));
130 spin_lock_init(&est->lock);
131 est->refcnt = 1;
132 est->params.interval = info->interval;
133 est->params.ewma_log = info->ewma_log;
134
135 cfg.opt.nla_len = nla_attr_size(sizeof(cfg.est));
136 cfg.opt.nla_type = TCA_STATS_RATE_EST;
137 cfg.est.interval = info->interval;
138 cfg.est.ewma_log = info->ewma_log;
139
140 ret = gen_new_estimator(&est->bstats, &est->rstats,
141 &est->lock, &cfg.opt);
142 if (ret < 0)
143 goto err2;
144
145 info->est = est;
146 xt_rateest_hash_insert(est);
147 return 0;
148
149 err2:
150 kfree(est);
151 err1:
152 return ret;
153 }
154
xt_rateest_tg_destroy(const struct xt_tgdtor_param * par)155 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
156 {
157 struct xt_rateest_target_info *info = par->targinfo;
158
159 xt_rateest_put(info->est);
160 }
161
162 static struct xt_target xt_rateest_tg_reg __read_mostly = {
163 .name = "RATEEST",
164 .revision = 0,
165 .family = NFPROTO_UNSPEC,
166 .target = xt_rateest_tg,
167 .checkentry = xt_rateest_tg_checkentry,
168 .destroy = xt_rateest_tg_destroy,
169 .targetsize = sizeof(struct xt_rateest_target_info),
170 .me = THIS_MODULE,
171 };
172
xt_rateest_tg_init(void)173 static int __init xt_rateest_tg_init(void)
174 {
175 unsigned int i;
176
177 for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
178 INIT_HLIST_HEAD(&rateest_hash[i]);
179
180 return xt_register_target(&xt_rateest_tg_reg);
181 }
182
xt_rateest_tg_fini(void)183 static void __exit xt_rateest_tg_fini(void)
184 {
185 xt_unregister_target(&xt_rateest_tg_reg);
186 }
187
188
189 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
190 MODULE_LICENSE("GPL");
191 MODULE_DESCRIPTION("Xtables: packet rate estimator");
192 MODULE_ALIAS("ipt_RATEEST");
193 MODULE_ALIAS("ip6t_RATEEST");
194 module_init(xt_rateest_tg_init);
195 module_exit(xt_rateest_tg_fini);
196