[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, 155 insertions, 0 deletions

diff --git a/net/netfilter/xt_physdev.c b/net/netfilter/xt_physdev.c
new file mode 100644
index 000000000000..19bb57c14dfe
--- /dev/null
+++ b/net/netfilter/xt_physdev.c
@@ -0,0 +1,155 @@
+/* Kernel module to match the bridge port in and
+ * out device for IP packets coming into contact with a bridge. */
+
+/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
+ *
+ * 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/netfilter/xt_physdev.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_bridge.h>
+#define MATCH   1
+#define NOMATCH 0
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
+MODULE_DESCRIPTION("iptables bridge physical device match module");
+MODULE_ALIAS("ipt_physdev");
+MODULE_ALIAS("ip6t_physdev");
+
+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)
+{
+	int i;
+	static const char nulldevname[IFNAMSIZ];
+	const struct xt_physdev_info *info = matchinfo;
+	unsigned int ret;
+	const char *indev, *outdev;
+	struct nf_bridge_info *nf_bridge;
+
+	/* Not a bridged IP packet or no info available yet:
+	 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
+	 * the destination device will be a bridge. */
+	if (!(nf_bridge = skb->nf_bridge)) {
+		/* Return MATCH if the invert flags of the used options are on */
+		if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
+		    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
+			return NOMATCH;
+		if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
+		    !(info->invert & XT_PHYSDEV_OP_ISIN))
+			return NOMATCH;
+		if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
+		    !(info->invert & XT_PHYSDEV_OP_ISOUT))
+			return NOMATCH;
+		if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
+		    !(info->invert & XT_PHYSDEV_OP_IN))
+			return NOMATCH;
+		if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
+		    !(info->invert & XT_PHYSDEV_OP_OUT))
+			return NOMATCH;
+		return MATCH;
+	}
+
+	/* This only makes sense in the FORWARD and POSTROUTING chains */
+	if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
+	    (!!(nf_bridge->mask & BRNF_BRIDGED) ^
+	    !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
+		return NOMATCH;
+
+	if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
+	    (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
+	    (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
+	    (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
+		return NOMATCH;
+
+	if (!(info->bitmask & XT_PHYSDEV_OP_IN))
+		goto match_outdev;
+	indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
+	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
+		ret |= (((const unsigned int *)indev)[i]
+			^ ((const unsigned int *)info->physindev)[i])
+			& ((const unsigned int *)info->in_mask)[i];
+	}
+
+	if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN))
+		return NOMATCH;
+
+match_outdev:
+	if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
+		return MATCH;
+	outdev = nf_bridge->physoutdev ?
+		 nf_bridge->physoutdev->name : nulldevname;
+	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
+		ret |= (((const unsigned int *)outdev)[i]
+			^ ((const unsigned int *)info->physoutdev)[i])
+			& ((const unsigned int *)info->out_mask)[i];
+	}
+
+	return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT);
+}
+
+static int
+checkentry(const char *tablename,
+		       const void *ip,
+		       void *matchinfo,
+		       unsigned int matchsize,
+		       unsigned int hook_mask)
+{
+	const struct xt_physdev_info *info = matchinfo;
+
+	if (matchsize != XT_ALIGN(sizeof(struct xt_physdev_info)))
+		return 0;
+	if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
+	    info->bitmask & ~XT_PHYSDEV_OP_MASK)
+		return 0;
+	return 1;
+}
+
+static struct xt_match physdev_match = {
+	.name		= "physdev",
+	.match		= &match,
+	.checkentry	= &checkentry,
+	.me		= THIS_MODULE,
+};
+
+static struct xt_match physdev6_match = {
+	.name		= "physdev",
+	.match		= &match,
+	.checkentry	= &checkentry,
+	.me		= THIS_MODULE,
+};
+
+static int __init init(void)
+{
+	int ret;
+
+	ret = xt_register_match(AF_INET, &physdev_match);
+	if (ret < 0)
+		return ret;
+
+	ret = xt_register_match(AF_INET6, &physdev6_match);
+	if (ret < 0)
+		xt_unregister_match(AF_INET, &physdev_match);
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_match(AF_INET, &physdev_match);
+	xt_unregister_match(AF_INET6, &physdev6_match);
+}
+
+module_init(init);
+module_exit(fini);