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 int 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);