[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables

This monster-patch tries to do the best job for unifying the data
structures and backend interfaces for the three evil clones ip_tables,
ip6_tables and arp_tables.  In an ideal world we would never have
allowed this kind of copy+paste programming... but well, our world
isn't (yet?) ideal.

o introduce a new x_tables module
o {ip,arp,ip6}_tables depend on this x_tables module
o registration functions for tables, matches and targets are only
  wrappers around x_tables provided functions
o all matches/targets that are used from ip_tables and ip6_tables
  are now implemented as xt_FOOBAR.c files and provide module aliases
  to ipt_FOOBAR and ip6t_FOOBAR
o header files for xt_matches are in include/linux/netfilter/,
  include/linux/netfilter_{ipv4,ipv6} contains compatibility wrappers
  around the xt_FOOBAR.h headers

Based on this patchset we're going to further unify the code,
gradually getting rid of all the layer 3 specific assumptions.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 109 insertions, 0 deletions

diff --git a/net/netfilter/xt_CLASSIFY.c b/net/netfilter/xt_CLASSIFY.c
new file mode 100644
index 000000000000..78ee266a12ee
--- /dev/null
+++ b/net/netfilter/xt_CLASSIFY.c
@@ -0,0 +1,109 @@
+/*
+ * This is a module which is used for setting the skb->priority field
+ * of an skb for qdisc classification.
+ */
+
+/* (C) 2001-2002 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/ip.h>
+#include <net/checksum.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_CLASSIFY.h>
+
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("iptables qdisc classification target module");
+MODULE_ALIAS("ipt_CLASSIFY");
+
+static unsigned int
+target(struct sk_buff **pskb,
+       const struct net_device *in,
+       const struct net_device *out,
+       unsigned int hooknum,
+       const void *targinfo,
+       void *userinfo)
+{
+	const struct xt_classify_target_info *clinfo = targinfo;
+
+	if ((*pskb)->priority != clinfo->priority)
+		(*pskb)->priority = clinfo->priority;
+
+	return XT_CONTINUE;
+}
+
+static int
+checkentry(const char *tablename,
+           const void *e,
+           void *targinfo,
+           unsigned int targinfosize,
+           unsigned int hook_mask)
+{
+	if (targinfosize != XT_ALIGN(sizeof(struct xt_classify_target_info))){
+		printk(KERN_ERR "CLASSIFY: invalid size (%u != %Zu).\n",
+		       targinfosize,
+		       XT_ALIGN(sizeof(struct xt_classify_target_info)));
+		return 0;
+	}
+	
+	if (hook_mask & ~((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_FORWARD) |
+	                  (1 << NF_IP_POST_ROUTING))) {
+		printk(KERN_ERR "CLASSIFY: only valid in LOCAL_OUT, FORWARD "
+		                "and POST_ROUTING.\n");
+		return 0;
+	}
+
+	if (strcmp(tablename, "mangle") != 0) {
+		printk(KERN_ERR "CLASSIFY: can only be called from "
+		                "\"mangle\" table, not \"%s\".\n",
+		                tablename);
+		return 0;
+	}
+
+	return 1;
+}
+
+static struct xt_target classify_reg = { 
+	.name 		= "CLASSIFY", 
+	.target 	= target,
+	.checkentry	= checkentry,
+	.me 		= THIS_MODULE,
+};
+static struct xt_target classify6_reg = { 
+	.name 		= "CLASSIFY", 
+	.target 	= target,
+	.checkentry	= checkentry,
+	.me 		= THIS_MODULE,
+};
+
+
+static int __init init(void)
+{
+	int ret;
+
+	ret = xt_register_target(AF_INET, &classify_reg);
+	if (ret)
+		return ret;
+
+	ret = xt_register_target(AF_INET6, &classify6_reg);
+	if (ret)
+		xt_unregister_target(AF_INET, &classify_reg);
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_target(AF_INET, &classify_reg);
+	xt_unregister_target(AF_INET6, &classify6_reg);
+}
+
+module_init(init);
+module_exit(fini);