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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 static bool rnd_inited __read_mostly;
 28 
 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 
 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 
 43 struct 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 }
 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                 /*
 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 }
 76 EXPORT_SYMBOL_GPL(xt_rateest_put);
 77 
 78 static unsigned int
 79 xt_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 
 92 static 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 
148 err2:
149         kfree(est);
150 err1:
151         return ret;
152 }
153 
154 static 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 
161 static 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 
172 static 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 
182 static void __exit xt_rateest_tg_fini(void)
183 {
184         xt_unregister_target(&xt_rateest_tg_reg);
185 }
186 
187 
188 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
189 MODULE_LICENSE("GPL");
190 MODULE_DESCRIPTION("Xtables: packet rate estimator");
191 MODULE_ALIAS("ipt_RATEEST");
192 MODULE_ALIAS("ip6t_RATEEST");
193 module_init(xt_rateest_tg_init);
194 module_exit(xt_rateest_tg_fini);
195 

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