1 files changed, 100 insertions, 0 deletions
diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c
new file mode 100644
index 00000000..42ecb71d
--- /dev/null
+++ b/net/netfilter/xt_statistic.c
@@ -0,0 +1,100 @@
+/*
+ * 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>
+
+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 ((net_random() & 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);