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 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         struct hlist_node *n;
  47         unsigned int h;
  48
  49         h = xt_rateest_hash(name);
  50         mutex_lock(&xt_rateest_mutex);
  51         hlist_for_each_entry(est, n, &rateest_hash[h], list) {
  52                 if (strcmp(est->name, name) == 0) {
  53                         est->refcnt++;
  54                         mutex_unlock(&xt_rateest_mutex);
  55                         return est;
  56                 }
  57         }
  58         mutex_unlock(&xt_rateest_mutex);
  59         return NULL;
  60 }
  61 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  62
  63 void xt_rateest_put(struct xt_rateest *est)
  64 {
  65         mutex_lock(&xt_rateest_mutex);
  66         if (--est->refcnt == 0) {
  67                 hlist_del(&est->list);
  68                 gen_kill_estimator(&est->bstats, &est->rstats);
  69                 kfree(est);
  70         }
  71         mutex_unlock(&xt_rateest_mutex);
  72 }
  73 EXPORT_SYMBOL_GPL(xt_rateest_put);
  74
  75 static unsigned int
  76 xt_rateest_tg(struct sk_buff *skb, const struct xt_target_param *par)
  77 {
  78         const struct xt_rateest_target_info *info = par->targinfo;
  79         struct gnet_stats_basic_packed *stats = &info->est->bstats;
  80
  81         spin_lock_bh(&info->est->lock);
  82         stats->bytes += skb->len;
  83         stats->packets++;
  84         spin_unlock_bh(&info->est->lock);
  85
  86         return XT_CONTINUE;
  87 }
  88
  89 static bool xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
  90 {
  91         struct xt_rateest_target_info *info = par->targinfo;
  92         struct xt_rateest *est;
  93         struct {
  94                 struct nlattr           opt;
  95                 struct gnet_estimator   est;
  96         } cfg;
  97
  98         if (unlikely(!rnd_inited)) {
  99                 get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 100                 rnd_inited = true;
 101         }
 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 false;
 114                 }
 115                 info->est = est;
 116                 return true;
 117         }
 118
 119         est = kzalloc(sizeof(*est), GFP_KERNEL);
 120         if (!est)
 121                 goto err1;
 122
 123         strlcpy(est->name, info->name, sizeof(est->name));
 124         spin_lock_init(&est->lock);
 125         est->refcnt             = 1;
 126         est->params.interval    = info->interval;
 127         est->params.ewma_log    = info->ewma_log;
 128
 129         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 130         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 131         cfg.est.interval        = info->interval;
 132         cfg.est.ewma_log        = info->ewma_log;
 133
 134         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
 135                               &cfg.opt) < 0)
 136                 goto err2;
 137
 138         info->est = est;
 139         xt_rateest_hash_insert(est);
 140
 141         return true;
 142
 143 err2:
 144         kfree(est);
 145 err1:
 146         return false;
 147 }
 148
 149 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 150 {
 151         struct xt_rateest_target_info *info = par->targinfo;
 152
 153         xt_rateest_put(info->est);
 154 }
 155
 156 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 157         .name       = "RATEEST",
 158         .revision   = 0,
 159         .family     = NFPROTO_UNSPEC,
 160         .target     = xt_rateest_tg,
 161         .checkentry = xt_rateest_tg_checkentry,
 162         .destroy    = xt_rateest_tg_destroy,
 163         .targetsize = sizeof(struct xt_rateest_target_info),
 164         .me         = THIS_MODULE,
 165 };
 166
 167 static int __init xt_rateest_tg_init(void)
 168 {
 169         unsigned int i;
 170
 171         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 172                 INIT_HLIST_HEAD(&rateest_hash[i]);
 173
 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);