x25: use limited socket backlog
[linux-2.6.git] / net / netfilter / xt_RATEEST.c
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 <net/gen_stats.h>
15 #include <net/netlink.h>
16
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_RATEEST.h>
19 #include <net/netfilter/xt_rateest.h>
20
21 static DEFINE_MUTEX(xt_rateest_mutex);
22
23 #define RATEEST_HSIZE   16
24 static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
25 static unsigned int jhash_rnd __read_mostly;
26 static bool rnd_inited __read_mostly;
27
28 static unsigned int xt_rateest_hash(const char *name)
29 {
30         return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) &
31                (RATEEST_HSIZE - 1);
32 }
33
34 static void xt_rateest_hash_insert(struct xt_rateest *est)
35 {
36         unsigned int h;
37
38         h = xt_rateest_hash(est->name);
39         hlist_add_head(&est->list, &rateest_hash[h]);
40 }
41
42 struct xt_rateest *xt_rateest_lookup(const char *name)
43 {
44         struct xt_rateest *est;
45         struct hlist_node *n;
46         unsigned int h;
47
48         h = xt_rateest_hash(name);
49         mutex_lock(&xt_rateest_mutex);
50         hlist_for_each_entry(est, n, &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 }
60 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
61
62 void 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                 kfree(est);
69         }
70         mutex_unlock(&xt_rateest_mutex);
71 }
72 EXPORT_SYMBOL_GPL(xt_rateest_put);
73
74 static unsigned int
75 xt_rateest_tg(struct sk_buff *skb, const struct xt_target_param *par)
76 {
77         const struct xt_rateest_target_info *info = par->targinfo;
78         struct gnet_stats_basic_packed *stats = &info->est->bstats;
79
80         spin_lock_bh(&info->est->lock);
81         stats->bytes += skb->len;
82         stats->packets++;
83         spin_unlock_bh(&info->est->lock);
84
85         return XT_CONTINUE;
86 }
87
88 static bool xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
89 {
90         struct xt_rateest_target_info *info = par->targinfo;
91         struct xt_rateest *est;
92         struct {
93                 struct nlattr           opt;
94                 struct gnet_estimator   est;
95         } cfg;
96
97         if (unlikely(!rnd_inited)) {
98                 get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
99                 rnd_inited = true;
100         }
101
102         est = xt_rateest_lookup(info->name);
103         if (est) {
104                 /*
105                  * If estimator parameters are specified, they must match the
106                  * existing estimator.
107                  */
108                 if ((!info->interval && !info->ewma_log) ||
109                     (info->interval != est->params.interval ||
110                      info->ewma_log != est->params.ewma_log)) {
111                         xt_rateest_put(est);
112                         return false;
113                 }
114                 info->est = est;
115                 return true;
116         }
117
118         est = kzalloc(sizeof(*est), GFP_KERNEL);
119         if (!est)
120                 goto err1;
121
122         strlcpy(est->name, info->name, sizeof(est->name));
123         spin_lock_init(&est->lock);
124         est->refcnt             = 1;
125         est->params.interval    = info->interval;
126         est->params.ewma_log    = info->ewma_log;
127
128         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
129         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
130         cfg.est.interval        = info->interval;
131         cfg.est.ewma_log        = info->ewma_log;
132
133         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
134                               &cfg.opt) < 0)
135                 goto err2;
136
137         info->est = est;
138         xt_rateest_hash_insert(est);
139
140         return true;
141
142 err2:
143         kfree(est);
144 err1:
145         return false;
146 }
147
148 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
149 {
150         struct xt_rateest_target_info *info = par->targinfo;
151
152         xt_rateest_put(info->est);
153 }
154
155 static struct xt_target xt_rateest_tg_reg __read_mostly = {
156         .name       = "RATEEST",
157         .revision   = 0,
158         .family     = NFPROTO_UNSPEC,
159         .target     = xt_rateest_tg,
160         .checkentry = xt_rateest_tg_checkentry,
161         .destroy    = xt_rateest_tg_destroy,
162         .targetsize = sizeof(struct xt_rateest_target_info),
163         .me         = THIS_MODULE,
164 };
165
166 static int __init xt_rateest_tg_init(void)
167 {
168         unsigned int i;
169
170         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
171                 INIT_HLIST_HEAD(&rateest_hash[i]);
172
173         return xt_register_target(&xt_rateest_tg_reg);
174 }
175
176 static void __exit xt_rateest_tg_fini(void)
177 {
178         xt_unregister_target(&xt_rateest_tg_reg);
179 }
180
181
182 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
183 MODULE_LICENSE("GPL");
184 MODULE_DESCRIPTION("Xtables: packet rate estimator");
185 MODULE_ALIAS("ipt_RATEEST");
186 MODULE_ALIAS("ip6t_RATEEST");
187 module_init(xt_rateest_tg_init);
188 module_exit(xt_rateest_tg_fini);