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 static void xt_rateest_free_rcu(struct rcu_head *head)
  64 {
  65         kfree(container_of(head, struct xt_rateest, rcu));
  66 }
  67
  68 void xt_rateest_put(struct xt_rateest *est)
  69 {
  70         mutex_lock(&xt_rateest_mutex);
  71         if (--est->refcnt == 0) {
  72                 hlist_del(&est->list);
  73                 gen_kill_estimator(&est->bstats, &est->rstats);
  74                 /*
  75                  * gen_estimator est_timer() might access est->lock or bstats,
  76                  * wait a RCU grace period before freeing 'est'
  77                  */
  78                 call_rcu(&est->rcu, xt_rateest_free_rcu);
  79         }
  80         mutex_unlock(&xt_rateest_mutex);
  81 }
  82 EXPORT_SYMBOL_GPL(xt_rateest_put);
  83
  84 static unsigned int
  85 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
  86 {
  87         const struct xt_rateest_target_info *info = par->targinfo;
  88         struct gnet_stats_basic_packed *stats = &info->est->bstats;
  89
  90         spin_lock_bh(&info->est->lock);
  91         stats->bytes += skb->len;
  92         stats->packets++;
  93         spin_unlock_bh(&info->est->lock);
  94
  95         return XT_CONTINUE;
  96 }
  97
  98 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
  99 {
 100         struct xt_rateest_target_info *info = par->targinfo;
 101         struct xt_rateest *est;
 102         struct {
 103                 struct nlattr           opt;
 104                 struct gnet_estimator   est;
 105         } cfg;
 106         int ret;
 107
 108         if (unlikely(!rnd_inited)) {
 109                 get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 110                 rnd_inited = true;
 111         }
 112
 113         est = xt_rateest_lookup(info->name);
 114         if (est) {
 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, &est->rstats,
 146                                 &est->lock, &cfg.opt);
 147         if (ret < 0)
 148                 goto err2;
 149
 150         info->est = est;
 151         xt_rateest_hash_insert(est);
 152         return 0;
 153
 154 err2:
 155         kfree(est);
 156 err1:
 157         return ret;
 158 }
 159
 160 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 161 {
 162         struct xt_rateest_target_info *info = par->targinfo;
 163
 164         xt_rateest_put(info->est);
 165 }
 166
 167 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 168         .name       = "RATEEST",
 169         .revision   = 0,
 170         .family     = NFPROTO_UNSPEC,
 171         .target     = xt_rateest_tg,
 172         .checkentry = xt_rateest_tg_checkentry,
 173         .destroy    = xt_rateest_tg_destroy,
 174         .targetsize = sizeof(struct xt_rateest_target_info),
 175         .me         = THIS_MODULE,
 176 };
 177
 178 static int __init xt_rateest_tg_init(void)
 179 {
 180         unsigned int i;
 181
 182         for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 183                 INIT_HLIST_HEAD(&rateest_hash[i]);
 184
 185         return xt_register_target(&xt_rateest_tg_reg);
 186 }
 187
 188 static void __exit xt_rateest_tg_fini(void)
 189 {
 190         xt_unregister_target(&xt_rateest_tg_reg);
 191         rcu_barrier(); /* Wait for completion of call_rcu()'s (xt_rateest_free_rcu) */
 192 }
 193
 194
 195 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 196 MODULE_LICENSE("GPL");
 197 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 198 MODULE_ALIAS("ipt_RATEEST");
 199 MODULE_ALIAS("ip6t_RATEEST");
 200 module_init(xt_rateest_tg_init);
 201 module_exit(xt_rateest_tg_fini);