43f5676b1af405d1a0c12a374710ae543d06346a
[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
27 static unsigned int xt_rateest_hash(const char *name)
28 {
29         return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) &
30                (RATEEST_HSIZE - 1);
31 }
32
33 static void xt_rateest_hash_insert(struct xt_rateest *est)
34 {
35         unsigned int h;
36
37         h = xt_rateest_hash(est->name);
38         hlist_add_head(&est->list, &rateest_hash[h]);
39 }
40
41 struct xt_rateest *xt_rateest_lookup(const char *name)
42 {
43         struct xt_rateest *est;
44         struct hlist_node *n;
45         unsigned int h;
46
47         h = xt_rateest_hash(name);
48         mutex_lock(&xt_rateest_mutex);
49         hlist_for_each_entry(est, n, &rateest_hash[h], list) {
50                 if (strcmp(est->name, name) == 0) {
51                         est->refcnt++;
52                         mutex_unlock(&xt_rateest_mutex);
53                         return est;
54                 }
55         }
56         mutex_unlock(&xt_rateest_mutex);
57         return NULL;
58 }
59 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
60
61 void xt_rateest_put(struct xt_rateest *est)
62 {
63         mutex_lock(&xt_rateest_mutex);
64         if (--est->refcnt == 0) {
65                 hlist_del(&est->list);
66                 gen_kill_estimator(&est->bstats, &est->rstats);
67                 kfree(est);
68         }
69         mutex_unlock(&xt_rateest_mutex);
70 }
71 EXPORT_SYMBOL_GPL(xt_rateest_put);
72
73 static unsigned int
74 xt_rateest_tg(struct sk_buff *skb, const struct xt_target_param *par)
75 {
76         const struct xt_rateest_target_info *info = par->targinfo;
77         struct gnet_stats_basic *stats = &info->est->bstats;
78
79         spin_lock_bh(&info->est->lock);
80         stats->bytes += skb->len;
81         stats->packets++;
82         spin_unlock_bh(&info->est->lock);
83
84         return XT_CONTINUE;
85 }
86
87 static bool xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
88 {
89         struct xt_rateest_target_info *info = par->targinfo;
90         struct xt_rateest *est;
91         struct {
92                 struct nlattr           opt;
93                 struct gnet_estimator   est;
94         } cfg;
95
96         est = xt_rateest_lookup(info->name);
97         if (est) {
98                 /*
99                  * If estimator parameters are specified, they must match the
100                  * existing estimator.
101                  */
102                 if ((!info->interval && !info->ewma_log) ||
103                     (info->interval != est->params.interval ||
104                      info->ewma_log != est->params.ewma_log)) {
105                         xt_rateest_put(est);
106                         return false;
107                 }
108                 info->est = est;
109                 return true;
110         }
111
112         est = kzalloc(sizeof(*est), GFP_KERNEL);
113         if (!est)
114                 goto err1;
115
116         strlcpy(est->name, info->name, sizeof(est->name));
117         spin_lock_init(&est->lock);
118         est->refcnt             = 1;
119         est->params.interval    = info->interval;
120         est->params.ewma_log    = info->ewma_log;
121
122         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
123         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
124         cfg.est.interval        = info->interval;
125         cfg.est.ewma_log        = info->ewma_log;
126
127         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
128                               &cfg.opt) < 0)
129                 goto err2;
130
131         info->est = est;
132         xt_rateest_hash_insert(est);
133
134         return true;
135
136 err2:
137         kfree(est);
138 err1:
139         return false;
140 }
141
142 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
143 {
144         struct xt_rateest_target_info *info = par->targinfo;
145
146         xt_rateest_put(info->est);
147 }
148
149 static struct xt_target xt_rateest_tg_reg __read_mostly = {
150         .name       = "RATEEST",
151         .revision   = 0,
152         .family     = NFPROTO_UNSPEC,
153         .target     = xt_rateest_tg,
154         .checkentry = xt_rateest_tg_checkentry,
155         .destroy    = xt_rateest_tg_destroy,
156         .targetsize = sizeof(struct xt_rateest_target_info),
157         .me         = THIS_MODULE,
158 };
159
160 static int __init xt_rateest_tg_init(void)
161 {
162         unsigned int i;
163
164         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
165                 INIT_HLIST_HEAD(&rateest_hash[i]);
166
167         get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
168         return xt_register_target(&xt_rateest_tg_reg);
169 }
170
171 static void __exit xt_rateest_tg_fini(void)
172 {
173         xt_unregister_target(&xt_rateest_tg_reg);
174 }
175
176
177 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
178 MODULE_LICENSE("GPL");
179 MODULE_DESCRIPTION("Xtables: packet rate estimator");
180 MODULE_ALIAS("ipt_RATEEST");
181 MODULE_ALIAS("ip6t_RATEEST");
182 module_init(xt_rateest_tg_init);
183 module_exit(xt_rateest_tg_fini);