[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, 238 insertions, 0 deletions

diff --git a/net/netfilter/xt_conntrack.c b/net/netfilter/xt_conntrack.c
new file mode 100644
index 00000000000..ffdebc95eb9
--- /dev/null
+++ b/net/netfilter/xt_conntrack.c
@@ -0,0 +1,238 @@
+/* Kernel module to match connection tracking information.
+ * Superset of Rusty's minimalistic state match.
+ *
+ * (C) 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>
+
+#if defined(CONFIG_IP_NF_CONNTRACK) || defined(CONFIG_IP_NF_CONNTRACK_MODULE)
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_conntrack_tuple.h>
+#else
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_conntrack.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
+MODULE_DESCRIPTION("iptables connection tracking match module");
+MODULE_ALIAS("ipt_conntrack");
+
+#if defined(CONFIG_IP_NF_CONNTRACK) || defined(CONFIG_IP_NF_CONNTRACK_MODULE)
+
+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_conntrack_info *sinfo = matchinfo;
+	struct ip_conntrack *ct;
+	enum ip_conntrack_info ctinfo;
+	unsigned int statebit;
+
+	ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
+
+#define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg))
+
+	if (ct == &ip_conntrack_untracked)
+		statebit = XT_CONNTRACK_STATE_UNTRACKED;
+	else if (ct)
+ 		statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
+ 	else
+ 		statebit = XT_CONNTRACK_STATE_INVALID;
+ 
+	if(sinfo->flags & XT_CONNTRACK_STATE) {
+		if (ct) {
+			if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip !=
+			    ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip)
+				statebit |= XT_CONNTRACK_STATE_SNAT;
+
+			if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip !=
+			    ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip)
+				statebit |= XT_CONNTRACK_STATE_DNAT;
+		}
+
+		if (FWINV((statebit & sinfo->statemask) == 0, XT_CONNTRACK_STATE))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_PROTO) {
+		if (!ct || FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum, XT_CONNTRACK_PROTO))
+                	return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_ORIGSRC) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip&sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip, XT_CONNTRACK_ORIGSRC))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_ORIGDST) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip&sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip, XT_CONNTRACK_ORIGDST))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_REPLSRC) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip&sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].src.ip, XT_CONNTRACK_REPLSRC))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_REPLDST) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip&sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].dst.ip, XT_CONNTRACK_REPLDST))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_STATUS) {
+		if (!ct || FWINV((ct->status & sinfo->statusmask) == 0, XT_CONNTRACK_STATUS))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_EXPIRES) {
+		unsigned long expires;
+
+		if(!ct)
+			return 0;
+
+		expires = timer_pending(&ct->timeout) ? (ct->timeout.expires - jiffies)/HZ : 0;
+
+		if (FWINV(!(expires >= sinfo->expires_min && expires <= sinfo->expires_max), XT_CONNTRACK_EXPIRES))
+			return 0;
+	}
+
+	return 1;
+}
+
+#else /* CONFIG_IP_NF_CONNTRACK */
+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_conntrack_info *sinfo = matchinfo;
+	struct nf_conn *ct;
+	enum ip_conntrack_info ctinfo;
+	unsigned int statebit;
+
+	ct = nf_ct_get((struct sk_buff *)skb, &ctinfo);
+
+#define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg))
+
+	if (ct == &nf_conntrack_untracked)
+		statebit = XT_CONNTRACK_STATE_UNTRACKED;
+	else if (ct)
+ 		statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
+ 	else
+ 		statebit = XT_CONNTRACK_STATE_INVALID;
+ 
+	if(sinfo->flags & XT_CONNTRACK_STATE) {
+		if (ct) {
+			if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip !=
+			    ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip)
+				statebit |= XT_CONNTRACK_STATE_SNAT;
+
+			if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip !=
+			    ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip)
+				statebit |= XT_CONNTRACK_STATE_DNAT;
+		}
+
+		if (FWINV((statebit & sinfo->statemask) == 0, XT_CONNTRACK_STATE))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_PROTO) {
+		if (!ct || FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum, XT_CONNTRACK_PROTO))
+                	return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_ORIGSRC) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip&sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip, XT_CONNTRACK_ORIGSRC))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_ORIGDST) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip&sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip, XT_CONNTRACK_ORIGDST))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_REPLSRC) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip&sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].src.ip, XT_CONNTRACK_REPLSRC))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_REPLDST) {
+		if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip&sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].dst.ip, XT_CONNTRACK_REPLDST))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_STATUS) {
+		if (!ct || FWINV((ct->status & sinfo->statusmask) == 0, XT_CONNTRACK_STATUS))
+			return 0;
+	}
+
+	if(sinfo->flags & XT_CONNTRACK_EXPIRES) {
+		unsigned long expires;
+
+		if(!ct)
+			return 0;
+
+		expires = timer_pending(&ct->timeout) ? (ct->timeout.expires - jiffies)/HZ : 0;
+
+		if (FWINV(!(expires >= sinfo->expires_min && expires <= sinfo->expires_max), XT_CONNTRACK_EXPIRES))
+			return 0;
+	}
+
+	return 1;
+}
+
+#endif /* CONFIG_NF_IP_CONNTRACK */
+
+static int check(const char *tablename,
+		 const void *ip,
+		 void *matchinfo,
+		 unsigned int matchsize,
+		 unsigned int hook_mask)
+{
+	if (matchsize != XT_ALIGN(sizeof(struct xt_conntrack_info)))
+		return 0;
+
+	return 1;
+}
+
+static struct xt_match conntrack_match = {
+	.name		= "conntrack",
+	.match		= &match,
+	.checkentry	= &check,
+	.me		= THIS_MODULE,
+};
+
+static int __init init(void)
+{
+	int ret;
+	need_conntrack();
+	ret = xt_register_match(AF_INET, &conntrack_match);
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	xt_unregister_match(AF_INET, &conntrack_match);
+}
+
+module_init(init);
+module_exit(fini);