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 static 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         hlist_for_each_entry(est, &rateest_hash[h], list) {
  49                 if (strcmp(est->name, name) == 0) {
  50                         est->refcnt++;
  51                         return est;
  52                 }
  53         }
  54
  55         return NULL;
  56 }
  57
  58 struct xt_rateest *xt_rateest_lookup(const char *name)
  59 {
  60         struct xt_rateest *est;
  61
  62         mutex_lock(&xt_rateest_mutex);
  63         est = __xt_rateest_lookup(name);
  64         mutex_unlock(&xt_rateest_mutex);
  65         return est;
  66 }
  67 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  68
  69 void xt_rateest_put(struct xt_rateest *est)
  70 {
  71         mutex_lock(&xt_rateest_mutex);
  72         if (--est->refcnt == 0) {
  73                 hlist_del(&est->list);
  74                 gen_kill_estimator(&est->bstats, &est->rstats);
  75                 /*
  76                  * gen_estimator est_timer() might access est->lock or bstats,
  77                  * wait a RCU grace period before freeing 'est'
  78                  */
  79                 kfree_rcu(est, rcu);
  80         }
  81         mutex_unlock(&xt_rateest_mutex);
  82 }
  83 EXPORT_SYMBOL_GPL(xt_rateest_put);
  84
  85 static unsigned int
  86 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
  87 {
  88         const struct xt_rateest_target_info *info = par->targinfo;
  89         struct gnet_stats_basic_packed *stats = &info->est->bstats;
  90
  91         spin_lock_bh(&info->est->lock);
  92         stats->bytes += skb->len;
  93         stats->packets++;
  94         spin_unlock_bh(&info->est->lock);
  95
  96         return XT_CONTINUE;
  97 }
  98
  99 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 100 {
 101         struct xt_rateest_target_info *info = par->targinfo;
 102         struct xt_rateest *est;
 103         struct {
 104                 struct nlattr           opt;
 105                 struct gnet_estimator   est;
 106         } cfg;
 107         int ret;
 108
 109         net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
 110
 111         mutex_lock(&xt_rateest_mutex);
 112         est = __xt_rateest_lookup(info->name);
 113         if (est) {
 114                 mutex_unlock(&xt_rateest_mutex);
 115                 /*
 116                  * If estimator parameters are specified, they must match the
 117                  * existing estimator.
 118                  */
 119                 if ((!info->interval && !info->ewma_log) ||
 120                     (info->interval != est->params.interval ||
 121                      info->ewma_log != est->params.ewma_log)) {
 122                         xt_rateest_put(est);
 123                         return -EINVAL;
 124                 }
 125                 info->est = est;
 126                 return 0;
 127         }
 128
 129         ret = -ENOMEM;
 130         est = kzalloc(sizeof(*est), GFP_KERNEL);
 131         if (!est)
 132                 goto err1;
 133
 134         strlcpy(est->name, info->name, sizeof(est->name));
 135         spin_lock_init(&est->lock);
 136         est->refcnt             = 1;
 137         est->params.interval    = info->interval;
 138         est->params.ewma_log    = info->ewma_log;
 139
 140         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 141         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 142         cfg.est.interval        = info->interval;
 143         cfg.est.ewma_log        = info->ewma_log;
 144
 145         ret = gen_new_estimator(&est->bstats, NULL, &est->rstats,
 146                                 &est->lock, NULL, &cfg.opt);
 147         if (ret < 0)
 148                 goto err2;
 149
 150         info->est = est;
 151         xt_rateest_hash_insert(est);
 152         mutex_unlock(&xt_rateest_mutex);
 153         return 0;
 154
 155 err2:
 156         kfree(est);
 157 err1:
 158         mutex_unlock(&xt_rateest_mutex);
 159         return ret;
 160 }
 161
 162 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 163 {
 164         struct xt_rateest_target_info *info = par->targinfo;
 165
 166         xt_rateest_put(info->est);
 167 }
 168
 169 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 170         .name       = "RATEEST",
 171         .revision   = 0,
 172         .family     = NFPROTO_UNSPEC,
 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 static int __init xt_rateest_tg_init(void)
 181 {
 182         unsigned int i;
 183
 184         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 185                 INIT_HLIST_HEAD(&rateest_hash[i]);
 186
 187         return xt_register_target(&xt_rateest_tg_reg);
 188 }
 189
 190 static void __exit xt_rateest_tg_fini(void)
 191 {
 192         xt_unregister_target(&xt_rateest_tg_reg);
 193 }
 194
 195
 196 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 197 MODULE_LICENSE("GPL");
 198 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 199 MODULE_ALIAS("ipt_RATEEST");
 200 MODULE_ALIAS("ip6t_RATEEST");
 201 module_init(xt_rateest_tg_init);
 202 module_exit(xt_rateest_tg_fini);