[NETFILTER]: x_tables: add statistic match

Add statistic match which is a combination of the nth and random matches.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 151 insertions, 0 deletions

diff --git a/include/linux/netfilter/xt_statistic.h b/include/linux/netfilter/xt_statistic.h
new file mode 100644
index 00000000000..c344e9916e2
--- /dev/null
+++ b/include/linux/netfilter/xt_statistic.h
@@ -0,0 +1,32 @@
+#ifndef _XT_STATISTIC_H
+#define _XT_STATISTIC_H
+
+enum xt_statistic_mode {
+        XT_STATISTIC_MODE_RANDOM,
+        XT_STATISTIC_MODE_NTH,
+        __XT_STATISTIC_MODE_MAX
+};
+#define XT_STATISTIC_MODE_MAX (__XT_STATISTIC_MODE_MAX - 1)
+
+enum xt_statistic_flags {
+        XT_STATISTIC_INVERT             = 0x1,
+};
+#define XT_STATISTIC_MASK               0x1
+
+struct xt_statistic_info {
+        u_int16_t                       mode;
+        u_int16_t                       flags;
+        union {
+                struct {
+                        u_int32_t       probability;
+                } random;
+                struct {
+                        u_int32_t       every;
+                        u_int32_t       packet;
+                        u_int32_t       count;
+                } nth;
+        } u;
+        struct xt_statistic_info        *master __attribute__((aligned(8)));
+};
+
+#endif /* _XT_STATISTIC_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 5543c7b7453..85a7e177025 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -375,6 +375,12 @@ config NETFILTER_XT_MATCH_STATE
 
           To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_MATCH_STATISTIC
+        tristate '"statistic" match support'
+        depends on NETFILTER_XTABLES
+        help
+          statistic module
+
 config NETFILTER_XT_MATCH_STRING
         tristate  '"string" match support'
         depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 4b6a6ea0737..df1da25f40d 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA) += xt_quota.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_REALM) += xt_realm.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_SCTP) += xt_sctp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_STATE) += xt_state.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_STATISTIC) += xt_statistic.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_STRING) += xt_string.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c
new file mode 100644
index 00000000000..de1037f5859
--- /dev/null
+++ b/net/netfilter/xt_statistic.c
@@ -0,0 +1,112 @@
+/*
+ * 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>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("xtables statistical match module");
+MODULE_ALIAS("ipt_statistic");
+MODULE_ALIAS("ip6t_statistic");
+
+static DEFINE_SPINLOCK(nth_lock);
+
+static int
+match(const struct sk_buff *skb,
+      const struct net_device *in, const struct net_device *out,
+      const struct xt_match *match, const void *matchinfo,
+      int offset, unsigned int protoff, int *hotdrop)
+{
+        struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo;
+        int ret = info->flags & XT_STATISTIC_INVERT ? 1 : 0;
+
+        switch (info->mode) {
+        case XT_STATISTIC_MODE_RANDOM:
+                if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
+                        ret ^= 1;
+                break;
+        case XT_STATISTIC_MODE_NTH:
+                info = info->master;
+                spin_lock_bh(&nth_lock);
+                if (info->u.nth.count++ == info->u.nth.every) {
+                        info->u.nth.count = 0;
+                        ret ^= 1;
+                }
+                spin_unlock_bh(&nth_lock);
+                break;
+        }
+
+        return ret;
+}
+
+static int
+checkentry(const char *tablename, const void *entry,
+           const struct xt_match *match, void *matchinfo,
+           unsigned int matchsize, unsigned int hook_mask)
+{
+        struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo;
+
+        if (info->mode > XT_STATISTIC_MODE_MAX ||
+            info->flags & ~XT_STATISTIC_MASK)
+                return 0;
+        info->master = info;
+        return 1;
+}
+
+static struct xt_match statistic_match = {
+        .name           = "statistic",
+        .match          = match,
+        .matchsize      = sizeof(struct xt_statistic_info),
+        .checkentry     = checkentry,
+        .family         = AF_INET,
+        .me             = THIS_MODULE,
+};
+
+static struct xt_match statistic_match6 = {
+        .name           = "statistic",
+        .match          = match,
+        .matchsize      = sizeof(struct xt_statistic_info),
+        .checkentry     = checkentry,
+        .family         = AF_INET6,
+        .me             = THIS_MODULE,
+};
+
+static int __init xt_statistic_init(void)
+{
+        int ret;
+
+        ret = xt_register_match(&statistic_match);
+        if (ret)
+                goto err1;
+
+        ret = xt_register_match(&statistic_match6);
+        if (ret)
+                goto err2;
+        return ret;
+err2:
+        xt_unregister_match(&statistic_match);
+err1:
+        return ret;
+}
+
+static void __exit xt_statistic_fini(void)
+{
+        xt_unregister_match(&statistic_match6);
+        xt_unregister_match(&statistic_match);
+}
+
+module_init(xt_statistic_init);
+module_exit(xt_statistic_fini);