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 static struct xt_rateest *__xt_rateest_lookup(const char *name)
  44 {
  45         struct xt_rateest *est;
  46         unsigned int h;
  47
  48         h = xt_rateest_hash(name);
  49         hlist_for_each_entry(est, &rateest_hash[h], list) {
  50                 if (strcmp(est->name, name) == 0) {
  51                         est->refcnt++;
  52                         return est;
  53                 }
  54         }
  55
  56         return NULL;
  57 }
  58
  59 struct xt_rateest *xt_rateest_lookup(const char *name)
  60 {
  61         struct xt_rateest *est;
  62
  63         mutex_lock(&xt_rateest_mutex);
  64         est = __xt_rateest_lookup(name);
  65         mutex_unlock(&xt_rateest_mutex);
  66         return est;
  67 }
  68 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  69
  70 void xt_rateest_put(struct xt_rateest *est)
  71 {
  72         mutex_lock(&xt_rateest_mutex);
  73         if (--est->refcnt == 0) {
  74                 hlist_del(&est->list);
  75                 gen_kill_estimator(&est->bstats, &est->rstats);
  76                 /*
  77                  * gen_estimator est_timer() might access est->lock or bstats,
  78                  * wait a RCU grace period before freeing 'est'
  79                  */
  80                 kfree_rcu(est, rcu);
  81         }
  82         mutex_unlock(&xt_rateest_mutex);
  83 }
  84 EXPORT_SYMBOL_GPL(xt_rateest_put);
  85
  86 static unsigned int
  87 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
  88 {
  89         const struct xt_rateest_target_info *info = par->targinfo;
  90         struct gnet_stats_basic_packed *stats = &info->est->bstats;
  91
  92         spin_lock_bh(&info->est->lock);
  93         stats->bytes += skb->len;
  94         stats->packets++;
  95         spin_unlock_bh(&info->est->lock);
  96
  97         return XT_CONTINUE;
  98 }
  99
 100 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 101 {
 102         struct xt_rateest_target_info *info = par->targinfo;
 103         struct xt_rateest *est;
 104         struct {
 105                 struct nlattr           opt;
 106                 struct gnet_estimator   est;
 107         } cfg;
 108         int ret;
 109
 110         if (strnlen(info->name, sizeof(est->name)) >= sizeof(est->name))
 111                 return -ENAMETOOLONG;
 112
 113         if (unlikely(!rnd_inited)) {
 114                 get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 115                 rnd_inited = true;
 116         }
 117
 118         mutex_lock(&xt_rateest_mutex);
 119         est = __xt_rateest_lookup(info->name);
 120         if (est) {
 121                 mutex_unlock(&xt_rateest_mutex);
 122                 /*
 123                  * If estimator parameters are specified, they must match the
 124                  * existing estimator.
 125                  */
 126                 if ((!info->interval && !info->ewma_log) ||
 127                     (info->interval != est->params.interval ||
 128                      info->ewma_log != est->params.ewma_log)) {
 129                         xt_rateest_put(est);
 130                         return -EINVAL;
 131                 }
 132                 info->est = est;
 133                 return 0;
 134         }
 135
 136         ret = -ENOMEM;
 137         est = kzalloc(sizeof(*est), GFP_KERNEL);
 138         if (!est)
 139                 goto err1;
 140
 141         strlcpy(est->name, info->name, sizeof(est->name));
 142         spin_lock_init(&est->lock);
 143         est->refcnt             = 1;
 144         est->params.interval    = info->interval;
 145         est->params.ewma_log    = info->ewma_log;
 146
 147         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 148         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 149         cfg.est.interval        = info->interval;
 150         cfg.est.ewma_log        = info->ewma_log;
 151
 152         ret = gen_new_estimator(&est->bstats, NULL, &est->rstats,
 153                                 &est->lock, &cfg.opt);
 154         if (ret < 0)
 155                 goto err2;
 156
 157         info->est = est;
 158         xt_rateest_hash_insert(est);
 159         mutex_unlock(&xt_rateest_mutex);
 160         return 0;
 161
 162 err2:
 163         kfree(est);
 164 err1:
 165         mutex_unlock(&xt_rateest_mutex);
 166         return ret;
 167 }
 168
 169 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 170 {
 171         struct xt_rateest_target_info *info = par->targinfo;
 172
 173         xt_rateest_put(info->est);
 174 }
 175
 176 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 177         .name       = "RATEEST",
 178         .revision   = 0,
 179         .family     = NFPROTO_UNSPEC,
 180         .target     = xt_rateest_tg,
 181         .checkentry = xt_rateest_tg_checkentry,
 182         .destroy    = xt_rateest_tg_destroy,
 183         .targetsize = sizeof(struct xt_rateest_target_info),
 184         .me         = THIS_MODULE,
 185 };
 186
 187 static int __init xt_rateest_tg_init(void)
 188 {
 189         unsigned int i;
 190
 191         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 192                 INIT_HLIST_HEAD(&rateest_hash[i]);
 193
 194         return xt_register_target(&xt_rateest_tg_reg);
 195 }
 196
 197 static void __exit xt_rateest_tg_fini(void)
 198 {
 199         xt_unregister_target(&xt_rateest_tg_reg);
 200 }
 201
 202
 203 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 204 MODULE_LICENSE("GPL");
 205 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 206 MODULE_ALIAS("ipt_RATEEST");
 207 MODULE_ALIAS("ip6t_RATEEST");
 208 module_init(xt_rateest_tg_init);
 209 module_exit(xt_rateest_tg_fini);