[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, 141 insertions, 0 deletions

diff --git a/net/netfilter/xt_CONNMARK.c b/net/netfilter/xt_CONNMARK.c
new file mode 100644
index 000000000000..22506e376be5
--- /dev/null
+++ b/net/netfilter/xt_CONNMARK.c
@@ -0,0 +1,141 @@
+/* This kernel module is used to modify the connection mark values, or
+ * to optionally restore the skb nfmark from the connection mark
+ *
+ * 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>
+#include <linux/ip.h>
+#include <net/checksum.h>
+
+MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
+MODULE_DESCRIPTION("IP tables CONNMARK matching 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 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_connmark_target_info *markinfo = targinfo;
+	u_int32_t diff;
+	u_int32_t nfmark;
+	u_int32_t newmark;
+	u_int32_t ctinfo;
+	u_int32_t *ctmark = nf_ct_get_mark(*pskb, &ctinfo);
+
+	if (ctmark) {
+	    switch(markinfo->mode) {
+	    case XT_CONNMARK_SET:
+		newmark = (*ctmark & ~markinfo->mask) | markinfo->mark;
+		if (newmark != *ctmark)
+		    *ctmark = newmark;
+		break;
+	    case XT_CONNMARK_SAVE:
+		newmark = (*ctmark & ~markinfo->mask) | ((*pskb)->nfmark & markinfo->mask);
+		if (*ctmark != newmark)
+		    *ctmark = newmark;
+		break;
+	    case XT_CONNMARK_RESTORE:
+		nfmark = (*pskb)->nfmark;
+		diff = (*ctmark ^ nfmark) & markinfo->mask;
+		if (diff != 0)
+		    (*pskb)->nfmark = nfmark ^ diff;
+		break;
+	    }
+	}
+
+	return XT_CONTINUE;
+}
+
+static int
+checkentry(const char *tablename,
+	   const void *entry,
+	   void *targinfo,
+	   unsigned int targinfosize,
+	   unsigned int hook_mask)
+{
+	struct xt_connmark_target_info *matchinfo = targinfo;
+	if (targinfosize != XT_ALIGN(sizeof(struct xt_connmark_target_info))) {
+		printk(KERN_WARNING "CONNMARK: targinfosize %u != %Zu\n",
+		       targinfosize,
+		       XT_ALIGN(sizeof(struct xt_connmark_target_info)));
+		return 0;
+	}
+
+	if (matchinfo->mode == XT_CONNMARK_RESTORE) {
+	    if (strcmp(tablename, "mangle") != 0) {
+		    printk(KERN_WARNING "CONNMARK: restore can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+		    return 0;
+	    }
+	}
+
+	if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
+		printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static struct xt_target connmark_reg = {
+	.name = "CONNMARK",
+	.target = &target,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+static struct xt_target connmark6_reg = {
+	.name = "CONNMARK",
+	.target = &target,
+	.checkentry = &checkentry,
+	.me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+	int ret;
+
+	need_conntrack();
+
+	ret = xt_register_target(AF_INET, &connmark_reg);
+	if (ret)
+		return ret;
+
+	ret = xt_register_target(AF_INET6, &connmark6_reg);
+	if (ret)
+		xt_unregister_target(AF_INET, &connmark_reg);
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_target(AF_INET, &connmark_reg);
+	xt_unregister_target(AF_INET6, &connmark6_reg);
+}
+
+module_init(init);
+module_exit(fini);