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,
  75               const struct net_device *in,
  76               const struct net_device *out,
  77               unsigned int hooknum,
  78               const struct xt_target *target,
  79               const void *targinfo)
  80 {
  81         const struct xt_rateest_target_info *info = targinfo;
  82         struct gnet_stats_basic *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 bool
  93 xt_rateest_tg_checkentry(const char *tablename,
  94                          const void *entry,
  95                          const struct xt_target *target,
  96                          void *targinfo,
  97                          unsigned int hook_mask)
  98 {
  99         struct xt_rateest_target_info *info = targinfo;
 100         struct xt_rateest *est;
 101         struct {
 102                 struct nlattr           opt;
 103                 struct gnet_estimator   est;
 104         } cfg;
 105
 106         est = xt_rateest_lookup(info->name);
 107         if (est) {
 108                 /*
 109                  * If estimator parameters are specified, they must match the
 110                  * existing estimator.
 111                  */
 112                 if ((!info->interval && !info->ewma_log) ||
 113                     (info->interval != est->params.interval ||
 114                      info->ewma_log != est->params.ewma_log)) {
 115                         xt_rateest_put(est);
 116                         return false;
 117                 }
 118                 info->est = est;
 119                 return true;
 120         }
 121
 122         est = kzalloc(sizeof(*est), GFP_KERNEL);
 123         if (!est)
 124                 goto err1;
 125
 126         strlcpy(est->name, info->name, sizeof(est->name));
 127         spin_lock_init(&est->lock);
 128         est->refcnt             = 1;
 129         est->params.interval    = info->interval;
 130         est->params.ewma_log    = info->ewma_log;
 131
 132         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 133         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 134         cfg.est.interval        = info->interval;
 135         cfg.est.ewma_log        = info->ewma_log;
 136
 137         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
 138                               &cfg.opt) < 0)
 139                 goto err2;
 140
 141         info->est = est;
 142         xt_rateest_hash_insert(est);
 143
 144         return true;
 145
 146 err2:
 147         kfree(est);
 148 err1:
 149         return false;
 150 }
 151
 152 static void xt_rateest_tg_destroy(const struct xt_target *target,
 153                                   void *targinfo)
 154 {
 155         struct xt_rateest_target_info *info = targinfo;
 156
 157         xt_rateest_put(info->est);
 158 }
 159
 160 static struct xt_target xt_rateest_target[] __read_mostly = {
 161         {
 162                 .family         = AF_INET,
 163                 .name           = "RATEEST",
 164                 .target         = xt_rateest_tg,
 165                 .checkentry     = xt_rateest_tg_checkentry,
 166                 .destroy        = xt_rateest_tg_destroy,
 167                 .targetsize     = sizeof(struct xt_rateest_target_info),
 168                 .me             = THIS_MODULE,
 169         },
 170         {
 171                 .family         = AF_INET6,
 172                 .name           = "RATEEST",
 173                 .target         = xt_rateest_tg,
 174                 .checkentry     = xt_rateest_tg_checkentry,
 175                 .destroy        = xt_rateest_tg_destroy,
 176                 .targetsize     = sizeof(struct xt_rateest_target_info),
 177                 .me             = THIS_MODULE,
 178         },
 179 };
 180
 181 static int __init xt_rateest_tg_init(void)
 182 {
 183         unsigned int i;
 184
 185         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 186                 INIT_HLIST_HEAD(&rateest_hash[i]);
 187
 188         get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 189         return xt_register_targets(xt_rateest_target,
 190                                    ARRAY_SIZE(xt_rateest_target));
 191 }
 192
 193 static void __exit xt_rateest_tg_fini(void)
 194 {
 195         xt_unregister_targets(xt_rateest_target, ARRAY_SIZE(xt_rateest_target));
 196 }
 197
 198
 199 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 200 MODULE_LICENSE("GPL");
 201 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 202 MODULE_ALIAS("ipt_RATEEST");
 203 MODULE_ALIAS("ip6t_RATEEST");
 204 module_init(xt_rateest_tg_init);
 205 module_exit(xt_rateest_tg_fini);