root/net/netfilter/xt_RATEEST.c

DEFINITIONS

1. xt_rateest_hash
2. xt_rateest_hash_insert
3. xt_rateest_lookup
4. xt_rateest_put
5. xt_rateest_tg
6. xt_rateest_tg_checkentry
7. xt_rateest_tg_destroy
8. xt_rateest_tg_init
9. xt_rateest_tg_fini

/*
 * (C) 2007 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/gen_stats.h>
#include <linux/jhash.h>
#include <linux/rtnetlink.h>
#include <linux/random.h>
#include <net/gen_stats.h>
#include <net/netlink.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_RATEEST.h>
#include <net/netfilter/xt_rateest.h>

static DEFINE_MUTEX(xt_rateest_mutex);

#define RATEEST_HSIZE   16
static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
static unsigned int jhash_rnd __read_mostly;

static unsigned int xt_rateest_hash(const char *name)
{
        return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) &
               (RATEEST_HSIZE - 1);
}

static void xt_rateest_hash_insert(struct xt_rateest *est)
{
        unsigned int h;

        h = xt_rateest_hash(est->name);
        hlist_add_head(&est->list, &rateest_hash[h]);
}

struct xt_rateest *xt_rateest_lookup(const char *name)
{
        struct xt_rateest *est;
        struct hlist_node *n;
        unsigned int h;

        h = xt_rateest_hash(name);
        mutex_lock(&xt_rateest_mutex);
        hlist_for_each_entry(est, n, &rateest_hash[h], list) {
                if (strcmp(est->name, name) == 0) {
                        est->refcnt++;
                        mutex_unlock(&xt_rateest_mutex);
                        return est;
                }
        }
        mutex_unlock(&xt_rateest_mutex);
        return NULL;
}
EXPORT_SYMBOL_GPL(xt_rateest_lookup);

void xt_rateest_put(struct xt_rateest *est)
{
        mutex_lock(&xt_rateest_mutex);
        if (--est->refcnt == 0) {
                hlist_del(&est->list);
                gen_kill_estimator(&est->bstats, &est->rstats);
                kfree(est);
        }
        mutex_unlock(&xt_rateest_mutex);
}
EXPORT_SYMBOL_GPL(xt_rateest_put);

static unsigned int
xt_rateest_tg(struct sk_buff *skb, const struct xt_target_param *par)
{
        const struct xt_rateest_target_info *info = par->targinfo;
        struct gnet_stats_basic *stats = &info->est->bstats;

        spin_lock_bh(&info->est->lock);
        stats->bytes += skb->len;
        stats->packets++;
        spin_unlock_bh(&info->est->lock);

        return XT_CONTINUE;
}

static bool xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
{
        struct xt_rateest_target_info *info = par->targinfo;
        struct xt_rateest *est;
        struct {
                struct nlattr           opt;
                struct gnet_estimator   est;
        } cfg;

        est = xt_rateest_lookup(info->name);
        if (est) {
                /*
                 * If estimator parameters are specified, they must match the
                 * existing estimator.
                 */
                if ((!info->interval && !info->ewma_log) ||
                    (info->interval != est->params.interval ||
                     info->ewma_log != est->params.ewma_log)) {
                        xt_rateest_put(est);
                        return false;
                }
                info->est = est;
                return true;
        }

        est = kzalloc(sizeof(*est), GFP_KERNEL);
        if (!est)
                goto err1;

        strlcpy(est->name, info->name, sizeof(est->name));
        spin_lock_init(&est->lock);
        est->refcnt             = 1;
        est->params.interval    = info->interval;
        est->params.ewma_log    = info->ewma_log;

        cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
        cfg.opt.nla_type        = TCA_STATS_RATE_EST;
        cfg.est.interval        = info->interval;
        cfg.est.ewma_log        = info->ewma_log;

        if (gen_new_estimator(&est->bstats, &est->rstats, &est->lock,
                              &cfg.opt) < 0)
                goto err2;

        info->est = est;
        xt_rateest_hash_insert(est);

        return true;

err2:
        kfree(est);
err1:
        return false;
}

static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
{
        struct xt_rateest_target_info *info = par->targinfo;

        xt_rateest_put(info->est);
}

static struct xt_target xt_rateest_tg_reg __read_mostly = {
        .name       = "RATEEST",
        .revision   = 0,
        .family     = NFPROTO_UNSPEC,
        .target     = xt_rateest_tg,
        .checkentry = xt_rateest_tg_checkentry,
        .destroy    = xt_rateest_tg_destroy,
        .targetsize = sizeof(struct xt_rateest_target_info),
        .me         = THIS_MODULE,
};

static int __init xt_rateest_tg_init(void)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
                INIT_HLIST_HEAD(&rateest_hash[i]);

        get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
        return xt_register_target(&xt_rateest_tg_reg);
}

static void __exit xt_rateest_tg_fini(void)
{
        xt_unregister_target(&xt_rateest_tg_reg);
}


MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: packet rate estimator");
MODULE_ALIAS("ipt_RATEEST");
MODULE_ALIAS("ip6t_RATEEST");
module_init(xt_rateest_tg_init);
module_exit(xt_rateest_tg_fini);