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
  88 xt_rateest_tg_checkentry(const char *tablename,
  89                          const void *entry,
  90                          const struct xt_target *target,
  91                          void *targinfo,
  92                          unsigned int hook_mask)
  93 {
  94         struct xt_rateest_target_info *info = targinfo;
  95         struct xt_rateest *est;
  96         struct {
  97                 struct nlattr           opt;
  98                 struct gnet_estimator   est;
  99         } cfg;
 100
 101         est = xt_rateest_lookup(info->name);
 102         if (est) {
 103                 /*
 104                  * If estimator parameters are specified, they must match the
 105                  * existing estimator.
 106                  */
 107                 if ((!info->interval && !info->ewma_log) ||
 108                     (info->interval != est->params.interval ||
 109                      info->ewma_log != est->params.ewma_log)) {
 110                         xt_rateest_put(est);
 111                         return false;
 112                 }
 113                 info->est = est;
 114                 return true;
 115         }
 116
 117         est = kzalloc(sizeof(*est), GFP_KERNEL);
 118         if (!est)
 119                 goto err1;
 120
 121         strlcpy(est->name, info->name, sizeof(est->name));
 122         spin_lock_init(&est->lock);
 123         est->refcnt             = 1;
 124         est->params.interval    = info->interval;
 125         est->params.ewma_log    = info->ewma_log;
 126
 127         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 128         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 129         cfg.est.interval        = info->interval;
 130         cfg.est.ewma_log        = info->ewma_log;
 131
 132         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
 133                               &cfg.opt) < 0)
 134                 goto err2;
 135
 136         info->est = est;
 137         xt_rateest_hash_insert(est);
 138
 139         return true;
 140
 141 err2:
 142         kfree(est);
 143 err1:
 144         return false;
 145 }
 146
 147 static void xt_rateest_tg_destroy(const struct xt_target *target,
 148                                   void *targinfo)
 149 {
 150         struct xt_rateest_target_info *info = 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         get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 174         return xt_register_target(&xt_rateest_tg_reg);
 175 }
 176
 177 static void __exit xt_rateest_tg_fini(void)
 178 {
 179         xt_unregister_target(&xt_rateest_tg_reg);
 180 }
 181
 182
 183 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 184 MODULE_LICENSE("GPL");
 185 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 186 MODULE_ALIAS("ipt_RATEEST");
 187 MODULE_ALIAS("ip6t_RATEEST");
 188 module_init(xt_rateest_tg_init);
 189 module_exit(xt_rateest_tg_fini);