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 <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->bstats, &est->rstats);
  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->rstats,
 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         .me         = THIS_MODULE,
 166 };
 167
 168 static int __init xt_rateest_tg_init(void)
 169 {
 170         unsigned int i;
 171
 172         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 173                 INIT_HLIST_HEAD(&rateest_hash[i]);
 174
 175         return xt_register_target(&xt_rateest_tg_reg);
 176 }
 177
 178 static void __exit xt_rateest_tg_fini(void)
 179 {
 180         xt_unregister_target(&xt_rateest_tg_reg);
 181 }
 182
 183
 184 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 185 MODULE_LICENSE("GPL");
 186 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 187 MODULE_ALIAS("ipt_RATEEST");
 188 MODULE_ALIAS("ip6t_RATEEST");
 189 module_init(xt_rateest_tg_init);
 190 module_exit(xt_rateest_tg_fini);