[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_connmark.c b/net/netfilter/xt_connmark.c
new file mode 100644
index 000000000000..d06e925032da
--- /dev/null
+++ b/net/netfilter/xt_connmark.c
@@ -0,0 +1,109 @@
+/* This kernel module matches connection mark values set by the
+ * CONNMARK target
+ *
+ * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
+ * by Henrik Nordstrom <hno@marasystems.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+
+MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
+MODULE_DESCRIPTION("IP tables connmark match module");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_connmark");
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_connmark.h>
+#include <net/netfilter/nf_conntrack_compat.h>
+
+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_connmark_info *info = matchinfo;
+	u_int32_t ctinfo;
+	const u_int32_t *ctmark = nf_ct_get_mark(skb, &ctinfo);
+	if (!ctmark)
+		return 0;
+
+	return (((*ctmark) & info->mask) == info->mark) ^ info->invert;
+}
+
+static int
+checkentry(const char *tablename,
+	   const void *ip,
+	   void *matchinfo,
+	   unsigned int matchsize,
+	   unsigned int hook_mask)
+{
+	struct xt_connmark_info *cm = 
+				(struct xt_connmark_info *)matchinfo;
+	if (matchsize != XT_ALIGN(sizeof(struct xt_connmark_info)))
+		return 0;
+
+	if (cm->mark > 0xffffffff || cm->mask > 0xffffffff) {
+		printk(KERN_WARNING "connmark: only support 32bit mark\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static struct xt_match connmark_match = {
+	.name = "connmark",
+	.match = &match,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+static struct xt_match connmark6_match = {
+	.name = "connmark",
+	.match = &match,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+
+
+static int __init init(void)
+{
+	int ret;
+
+	need_conntrack();
+
+	ret = xt_register_match(AF_INET, &connmark_match);
+	if (ret)
+		return ret;
+
+	ret = xt_register_match(AF_INET6, &connmark6_match);
+	if (ret)
+		xt_unregister_match(AF_INET, &connmark_match);
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_match(AF_INET6, &connmark6_match);
+	xt_unregister_match(AF_INET, &connmark_match);
+}
+
+module_init(init);
+module_exit(fini);