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 xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
  88 {
  89         struct xt_rateest_target_info *info = par->targinfo;
  90         struct xt_rateest *est;
  91         struct {
  92                 struct nlattr           opt;
  93                 struct gnet_estimator   est;
  94         } cfg;
  95
  96         est = xt_rateest_lookup(info->name);
  97         if (est) {
  98                 /*
  99                  * If estimator parameters are specified, they must match the
 100                  * existing estimator.
 101                  */
 102                 if ((!info->interval && !info->ewma_log) ||
 103                     (info->interval != est->params.interval ||
 104                      info->ewma_log != est->params.ewma_log)) {
 105                         xt_rateest_put(est);
 106                         return false;
 107                 }
 108                 info->est = est;
 109                 return true;
 110         }
 111
 112         est = kzalloc(sizeof(*est), GFP_KERNEL);
 113         if (!est)
 114                 goto err1;
 115
 116         strlcpy(est->name, info->name, sizeof(est->name));
 117         spin_lock_init(&est->lock);
 118         est->refcnt             = 1;
 119         est->params.interval    = info->interval;
 120         est->params.ewma_log    = info->ewma_log;
 121
 122         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 123         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 124         cfg.est.interval        = info->interval;
 125         cfg.est.ewma_log        = info->ewma_log;
 126
 127         if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
 128                               &cfg.opt) < 0)
 129                 goto err2;
 130
 131         info->est = est;
 132         xt_rateest_hash_insert(est);
 133
 134         return true;
 135
 136 err2:
 137         kfree(est);
 138 err1:
 139         return false;
 140 }
 141
 142 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 143 {
 144         struct xt_rateest_target_info *info = par->targinfo;
 145
 146         xt_rateest_put(info->est);
 147 }
 148
 149 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 150         .name       = "RATEEST",
 151         .revision   = 0,
 152         .family     = NFPROTO_UNSPEC,
 153         .target     = xt_rateest_tg,
 154         .checkentry = xt_rateest_tg_checkentry,
 155         .destroy    = xt_rateest_tg_destroy,
 156         .targetsize = sizeof(struct xt_rateest_target_info),
 157         .me         = THIS_MODULE,
 158 };
 159
 160 static int __init xt_rateest_tg_init(void)
 161 {
 162         unsigned int i;
 163
 164         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 165                 INIT_HLIST_HEAD(&rateest_hash[i]);
 166
 167         get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 168         return xt_register_target(&xt_rateest_tg_reg);
 169 }
 170
 171 static void __exit xt_rateest_tg_fini(void)
 172 {
 173         xt_unregister_target(&xt_rateest_tg_reg);
 174 }
 175
 176
 177 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 178 MODULE_LICENSE("GPL");
 179 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 180 MODULE_ALIAS("ipt_RATEEST");
 181 MODULE_ALIAS("ip6t_RATEEST");
 182 module_init(xt_rateest_tg_init);
 183 module_exit(xt_rateest_tg_fini);