| /* |
| * Copyright (c) 2006 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. |
| * |
| * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>. |
| */ |
| |
| #include <linux/init.h> |
| #include <linux/spinlock.h> |
| #include <linux/skbuff.h> |
| #include <linux/net.h> |
| |
| #include <linux/netfilter/xt_statistic.h> |
| #include <linux/netfilter/x_tables.h> |
| |
| struct xt_statistic_priv { |
| uint32_t count; |
| }; |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
| MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); |
| MODULE_ALIAS("ipt_statistic"); |
| MODULE_ALIAS("ip6t_statistic"); |
| |
| static DEFINE_SPINLOCK(nth_lock); |
| |
| static bool |
| statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
| { |
| const struct xt_statistic_info *info = par->matchinfo; |
| bool ret = info->flags & XT_STATISTIC_INVERT; |
| |
| switch (info->mode) { |
| case XT_STATISTIC_MODE_RANDOM: |
| if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) |
| ret = !ret; |
| break; |
| case XT_STATISTIC_MODE_NTH: |
| spin_lock_bh(&nth_lock); |
| if (info->master->count++ == info->u.nth.every) { |
| info->master->count = 0; |
| ret = !ret; |
| } |
| spin_unlock_bh(&nth_lock); |
| break; |
| } |
| |
| return ret; |
| } |
| |
| static int statistic_mt_check(const struct xt_mtchk_param *par) |
| { |
| struct xt_statistic_info *info = par->matchinfo; |
| |
| if (info->mode > XT_STATISTIC_MODE_MAX || |
| info->flags & ~XT_STATISTIC_MASK) |
| return -EINVAL; |
| |
| info->master = kzalloc(sizeof(*info->master), GFP_KERNEL); |
| if (info->master == NULL) |
| return -EINVAL; |
| info->master->count = info->u.nth.count; |
| |
| return 0; |
| } |
| |
| static void statistic_mt_destroy(const struct xt_mtdtor_param *par) |
| { |
| const struct xt_statistic_info *info = par->matchinfo; |
| |
| kfree(info->master); |
| } |
| |
| static struct xt_match xt_statistic_mt_reg __read_mostly = { |
| .name = "statistic", |
| .revision = 0, |
| .family = NFPROTO_UNSPEC, |
| .match = statistic_mt, |
| .checkentry = statistic_mt_check, |
| .destroy = statistic_mt_destroy, |
| .matchsize = sizeof(struct xt_statistic_info), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init statistic_mt_init(void) |
| { |
| return xt_register_match(&xt_statistic_mt_reg); |
| } |
| |
| static void __exit statistic_mt_exit(void) |
| { |
| xt_unregister_match(&xt_statistic_mt_reg); |
| } |
| |
| module_init(statistic_mt_init); |
| module_exit(statistic_mt_exit); |