[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, 191 insertions, 0 deletions

diff --git a/net/netfilter/xt_MARK.c b/net/netfilter/xt_MARK.c
new file mode 100644
index 00000000000..0c11ee9550f
--- /dev/null
+++ b/net/netfilter/xt_MARK.c
@@ -0,0 +1,191 @@
+/* This is a module which is used for setting the NFMARK field of an skb. */
+
+/* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
+ *
+ * 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_MARK.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
+MODULE_DESCRIPTION("ip[6]tables MARK modification module");
+MODULE_ALIAS("ipt_MARK");
+MODULE_ALIAS("ip6t_MARK");
+
+static unsigned int
+target_v0(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_mark_target_info *markinfo = targinfo;
+
+	if((*pskb)->nfmark != markinfo->mark)
+		(*pskb)->nfmark = markinfo->mark;
+
+	return XT_CONTINUE;
+}
+
+static unsigned int
+target_v1(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_mark_target_info_v1 *markinfo = targinfo;
+	int mark = 0;
+
+	switch (markinfo->mode) {
+	case XT_MARK_SET:
+		mark = markinfo->mark;
+		break;
+		
+	case XT_MARK_AND:
+		mark = (*pskb)->nfmark & markinfo->mark;
+		break;
+		
+	case XT_MARK_OR:
+		mark = (*pskb)->nfmark | markinfo->mark;
+		break;
+	}
+
+	if((*pskb)->nfmark != mark)
+		(*pskb)->nfmark = mark;
+
+	return XT_CONTINUE;
+}
+
+
+static int
+checkentry_v0(const char *tablename,
+	      const void *entry,
+	      void *targinfo,
+	      unsigned int targinfosize,
+	      unsigned int hook_mask)
+{
+	struct xt_mark_target_info *markinfo = targinfo;
+
+	if (targinfosize != XT_ALIGN(sizeof(struct xt_mark_target_info))) {
+		printk(KERN_WARNING "MARK: targinfosize %u != %Zu\n",
+		       targinfosize,
+		       XT_ALIGN(sizeof(struct xt_mark_target_info)));
+		return 0;
+	}
+
+	if (strcmp(tablename, "mangle") != 0) {
+		printk(KERN_WARNING "MARK: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+		return 0;
+	}
+
+	if (markinfo->mark > 0xffffffff) {
+		printk(KERN_WARNING "MARK: Only supports 32bit wide mark\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static int
+checkentry_v1(const char *tablename,
+	      const void *entry,
+	      void *targinfo,
+	      unsigned int targinfosize,
+	      unsigned int hook_mask)
+{
+	struct xt_mark_target_info_v1 *markinfo = targinfo;
+
+	if (targinfosize != XT_ALIGN(sizeof(struct xt_mark_target_info_v1))){
+		printk(KERN_WARNING "MARK: targinfosize %u != %Zu\n",
+		       targinfosize,
+		       XT_ALIGN(sizeof(struct xt_mark_target_info_v1)));
+		return 0;
+	}
+
+	if (strcmp(tablename, "mangle") != 0) {
+		printk(KERN_WARNING "MARK: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+		return 0;
+	}
+
+	if (markinfo->mode != XT_MARK_SET
+	    && markinfo->mode != XT_MARK_AND
+	    && markinfo->mode != XT_MARK_OR) {
+		printk(KERN_WARNING "MARK: unknown mode %u\n",
+		       markinfo->mode);
+		return 0;
+	}
+
+	if (markinfo->mark > 0xffffffff) {
+		printk(KERN_WARNING "MARK: Only supports 32bit wide mark\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static struct xt_target ipt_mark_reg_v0 = {
+	.name		= "MARK",
+	.target		= target_v0,
+	.checkentry	= checkentry_v0,
+	.me		= THIS_MODULE,
+	.revision	= 0,
+};
+
+static struct xt_target ipt_mark_reg_v1 = {
+	.name		= "MARK",
+	.target		= target_v1,
+	.checkentry	= checkentry_v1,
+	.me		= THIS_MODULE,
+	.revision	= 1,
+};
+
+static struct xt_target ip6t_mark_reg_v0 = {
+	.name		= "MARK",
+	.target		= target_v0,
+	.checkentry	= checkentry_v0,
+	.me		= THIS_MODULE,
+	.revision	= 0,
+};
+
+static int __init init(void)
+{
+	int err;
+
+	err = xt_register_target(AF_INET, &ipt_mark_reg_v0);
+	if (err)
+		return err;
+
+	err = xt_register_target(AF_INET, &ipt_mark_reg_v1);
+	if (err)
+		xt_unregister_target(AF_INET, &ipt_mark_reg_v0);
+
+	err = xt_register_target(AF_INET6, &ip6t_mark_reg_v0);
+	if (err) {
+		xt_unregister_target(AF_INET, &ipt_mark_reg_v0);
+		xt_unregister_target(AF_INET, &ipt_mark_reg_v1);
+	}
+
+	return err;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_target(AF_INET, &ipt_mark_reg_v0);
+	xt_unregister_target(AF_INET, &ipt_mark_reg_v1);
+	xt_unregister_target(AF_INET6, &ip6t_mark_reg_v0);
+}
+
+module_init(init);
+module_exit(fini);