linux/net/netfilter/xt_RATEEST.c
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   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
  22static DEFINE_MUTEX(xt_rateest_mutex);
  23
  24#define RATEEST_HSIZE   16
  25static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
  26static unsigned int jhash_rnd __read_mostly;
  27static bool rnd_inited __read_mostly;
  28
  29static 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
  35static 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
  43struct 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}
  60EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  61
  62void 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}
  76EXPORT_SYMBOL_GPL(xt_rateest_put);
  77
  78static unsigned int
  79xt_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
  92static 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
 148err2:
 149        kfree(est);
 150err1:
 151        return ret;
 152}
 153
 154static 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
 161static 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
 172static 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
 182static void __exit xt_rateest_tg_fini(void)
 183{
 184        xt_unregister_target(&xt_rateest_tg_reg);
 185}
 186
 187
 188MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 189MODULE_LICENSE("GPL");
 190MODULE_DESCRIPTION("Xtables: packet rate estimator");
 191MODULE_ALIAS("ipt_RATEEST");
 192MODULE_ALIAS("ip6t_RATEEST");
 193module_init(xt_rateest_tg_init);
 194module_exit(xt_rateest_tg_fini);
 195
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