diff options
Diffstat (limited to 'net/netfilter/xt_statistic.c')
-rw-r--r-- | net/netfilter/xt_statistic.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c new file mode 100644 index 000000000..11de55e7a --- /dev/null +++ b/net/netfilter/xt_statistic.c @@ -0,0 +1,101 @@ +/* + * 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/slab.h> + +#include <linux/netfilter/xt_statistic.h> +#include <linux/netfilter/x_tables.h> +#include <linux/module.h> + +struct xt_statistic_priv { + atomic_t count; +} ____cacheline_aligned_in_smp; + +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 bool +statistic_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_statistic_info *info = par->matchinfo; + bool ret = info->flags & XT_STATISTIC_INVERT; + int nval, oval; + + switch (info->mode) { + case XT_STATISTIC_MODE_RANDOM: + if ((prandom_u32() & 0x7FFFFFFF) < info->u.random.probability) + ret = !ret; + break; + case XT_STATISTIC_MODE_NTH: + do { + oval = atomic_read(&info->master->count); + nval = (oval == info->u.nth.every) ? 0 : oval + 1; + } while (atomic_cmpxchg(&info->master->count, oval, nval) != oval); + if (nval == 0) + ret = !ret; + 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 -ENOMEM; + atomic_set(&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); |