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