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TOMOYO Linux Cross Reference
Linux/net/netfilter/xt_RATEEST.c

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

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