[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, 100 insertions, 0 deletions

diff --git a/net/netfilter/xt_mac.c b/net/netfilter/xt_mac.c
new file mode 100644
index 000000000000..0461dcb5fc7a
--- /dev/null
+++ b/net/netfilter/xt_mac.c
@@ -0,0 +1,100 @@
+/* Kernel module to match MAC address parameters. */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * 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/if_ether.h>
+#include <linux/etherdevice.h>
+
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter/xt_mac.h>
+#include <linux/netfilter/x_tables.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
+MODULE_DESCRIPTION("iptables mac matching module");
+MODULE_ALIAS("ipt_mac");
+MODULE_ALIAS("ip6t_mac");
+
+static int
+match(const struct sk_buff *skb,
+      const struct net_device *in,
+      const struct net_device *out,
+      const void *matchinfo,
+      int offset,
+      unsigned int protoff,
+      int *hotdrop)
+{
+    const struct xt_mac_info *info = matchinfo;
+
+    /* Is mac pointer valid? */
+    return (skb->mac.raw >= skb->head
+	    && (skb->mac.raw + ETH_HLEN) <= skb->data
+	    /* If so, compare... */
+	    && ((!compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr))
+		^ info->invert));
+}
+
+static int
+ipt_mac_checkentry(const char *tablename,
+		   const void *inf,
+		   void *matchinfo,
+		   unsigned int matchsize,
+		   unsigned int hook_mask)
+{
+	/* FORWARD isn't always valid, but it's nice to be able to do --RR */
+	if (hook_mask
+	    & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)
+		| (1 << NF_IP_FORWARD))) {
+		printk("xt_mac: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");
+		return 0;
+	}
+
+	if (matchsize != XT_ALIGN(sizeof(struct xt_mac_info)))
+		return 0;
+
+	return 1;
+}
+
+static struct xt_match mac_match = {
+	.name		= "mac",
+	.match		= &match,
+	.checkentry	= &ipt_mac_checkentry,
+	.me		= THIS_MODULE,
+};
+static struct xt_match mac6_match = {
+	.name		= "mac",
+	.match		= &match,
+	.checkentry	= &ipt_mac_checkentry,
+	.me		= THIS_MODULE,
+};
+
+static int __init init(void)
+{
+	int ret;
+	ret = xt_register_match(AF_INET, &mac_match);
+	if (ret)
+		return ret;
+
+	ret = xt_register_match(AF_INET6, &mac6_match);
+	if (ret)
+		xt_unregister_match(AF_INET, &mac_match);
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_match(AF_INET, &mac_match);
+	xt_unregister_match(AF_INET6, &mac6_match);
+}
+
+module_init(init);
+module_exit(fini);