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