[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>

include/linux/netfilter/nf_conntrack_common.h

@@ -154,6 +154,9 @@ struct ip_conntrack_stat
 	unsigned int expect_delete;
 };
 
+/* call to create an explicit dependency on nf_conntrack. */
+extern void need_conntrack(void);
+
 #endif /* __KERNEL__ */
 
 #endif /* _NF_CONNTRACK_COMMON_H */

include/linux/netfilter/x_tables.h

@@ -0,0 +1,224 @@
+#ifndef _X_TABLES_H
+#define _X_TABLES_H
+
+#define XT_FUNCTION_MAXNAMELEN 30
+#define XT_TABLE_MAXNAMELEN 32
+
+/* The argument to IPT_SO_GET_REVISION_*.  Returns highest revision
+ * kernel supports, if >= revision. */
+struct xt_get_revision
+{
+	char name[XT_FUNCTION_MAXNAMELEN-1];
+
+	u_int8_t revision;
+};
+
+/* CONTINUE verdict for targets */
+#define XT_CONTINUE 0xFFFFFFFF
+
+/* For standard target */
+#define XT_RETURN (-NF_REPEAT - 1)
+
+#define XT_ALIGN(s) (((s) + (__alignof__(void *)-1)) & ~(__alignof__(void *)-1))
+
+/* Standard return verdict, or do jump. */
+#define XT_STANDARD_TARGET ""
+/* Error verdict. */
+#define XT_ERROR_TARGET "ERROR"
+
+/*
+ * New IP firewall options for [gs]etsockopt at the RAW IP level.
+ * Unlike BSD Linux inherits IP options so you don't have to use a raw
+ * socket for this. Instead we check rights in the calls. */
+#define XT_BASE_CTL		64	/* base for firewall socket options */
+
+#define XT_SO_SET_REPLACE	(XT_BASE_CTL)
+#define XT_SO_SET_ADD_COUNTERS	(XT_BASE_CTL + 1)
+#define XT_SO_SET_MAX		XT_SO_SET_ADD_COUNTERS
+
+#define XT_SO_GET_INFO			(XT_BASE_CTL)
+#define XT_SO_GET_ENTRIES		(XT_BASE_CTL + 1)
+#define XT_SO_GET_REVISION_MATCH	(XT_BASE_CTL + 2)
+#define XT_SO_GET_REVISION_TARGET	(XT_BASE_CTL + 3)
+#define XT_SO_GET_MAX			XT_SO_GET_REVISION_TARGET
+
+#define SET_COUNTER(c,b,p) do { (c).bcnt = (b); (c).pcnt = (p); } while(0)
+#define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
+
+struct xt_counters
+{
+	u_int64_t pcnt, bcnt;			/* Packet and byte counters */
+};
+
+/* The argument to IPT_SO_ADD_COUNTERS. */
+struct xt_counters_info
+{
+	/* Which table. */
+	char name[XT_TABLE_MAXNAMELEN];
+
+	unsigned int num_counters;
+
+	/* The counters (actually `number' of these). */
+	struct xt_counters counters[0];
+};
+
+#define XT_INV_PROTO		0x40	/* Invert the sense of PROTO. */
+
+#ifdef __KERNEL__
+
+#include <linux/netdevice.h>
+
+#define ASSERT_READ_LOCK(x)
+#define ASSERT_WRITE_LOCK(x)
+#include <linux/netfilter_ipv4/listhelp.h>
+
+struct xt_match
+{
+	struct list_head list;
+
+	const char name[XT_FUNCTION_MAXNAMELEN-1];
+
+	u_int8_t revision;
+
+	/* Return true or false: return FALSE and set *hotdrop = 1 to
+           force immediate packet drop. */
+	/* Arguments changed since 2.6.9, as this must now handle
+	   non-linear skb, using skb_header_pointer and
+	   skb_ip_make_writable. */
+	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);
+
+	/* Called when user tries to insert an entry of this type. */
+	/* Should return true or false. */
+	int (*checkentry)(const char *tablename,
+			  const void *ip,
+			  void *matchinfo,
+			  unsigned int matchinfosize,
+			  unsigned int hook_mask);
+
+	/* Called when entry of this type deleted. */
+	void (*destroy)(void *matchinfo, unsigned int matchinfosize);
+
+	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
+	struct module *me;
+};
+
+/* Registration hooks for targets. */
+struct xt_target
+{
+	struct list_head list;
+
+	const char name[XT_FUNCTION_MAXNAMELEN-1];
+
+	u_int8_t revision;
+
+	/* Returns verdict. Argument order changed since 2.6.9, as this
+	   must now handle non-linear skbs, using skb_copy_bits and
+	   skb_ip_make_writable. */
+	unsigned int (*target)(struct sk_buff **pskb,
+			       const struct net_device *in,
+			       const struct net_device *out,
+			       unsigned int hooknum,
+			       const void *targinfo,
+			       void *userdata);
+
+	/* Called when user tries to insert an entry of this type:
+           hook_mask is a bitmask of hooks from which it can be
+           called. */
+	/* Should return true or false. */
+	int (*checkentry)(const char *tablename,
+			  const void *entry,
+			  void *targinfo,
+			  unsigned int targinfosize,
+			  unsigned int hook_mask);
+
+	/* Called when entry of this type deleted. */
+	void (*destroy)(void *targinfo, unsigned int targinfosize);
+
+	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
+	struct module *me;
+};
+
+/* Furniture shopping... */
+struct xt_table
+{
+	struct list_head list;
+
+	/* A unique name... */
+	char name[XT_TABLE_MAXNAMELEN];
+
+	/* What hooks you will enter on */
+	unsigned int valid_hooks;
+
+	/* Lock for the curtain */
+	rwlock_t lock;
+
+	/* Man behind the curtain... */
+	//struct ip6t_table_info *private;
+	void *private;
+
+	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
+	struct module *me;
+
+	int af;		/* address/protocol family */
+};
+
+#include <linux/netfilter_ipv4.h>
+
+/* The table itself */
+struct xt_table_info
+{
+	/* Size per table */
+	unsigned int size;
+	/* Number of entries: FIXME. --RR */
+	unsigned int number;
+	/* Initial number of entries. Needed for module usage count */
+	unsigned int initial_entries;
+
+	/* Entry points and underflows */
+	unsigned int hook_entry[NF_IP_NUMHOOKS];
+	unsigned int underflow[NF_IP_NUMHOOKS];
+
+	/* ipt_entry tables: one per CPU */
+	char *entries[NR_CPUS];
+};
+
+extern int xt_register_target(int af, struct xt_target *target);
+extern void xt_unregister_target(int af, struct xt_target *target);
+extern int xt_register_match(int af, struct xt_match *target);
+extern void xt_unregister_match(int af, struct xt_match *target);
+
+extern int xt_register_table(struct xt_table *table,
+			     struct xt_table_info *bootstrap,
+			     struct xt_table_info *newinfo);
+extern void *xt_unregister_table(struct xt_table *table);
+
+extern struct xt_table_info *xt_replace_table(struct xt_table *table,
+					      unsigned int num_counters,
+					      struct xt_table_info *newinfo,
+					      int *error);
+
+extern struct xt_match *xt_find_match(int af, const char *name, u8 revision);
+extern struct xt_target *xt_find_target(int af, const char *name, u8 revision);
+extern struct xt_target *xt_request_find_target(int af, const char *name, 
+						u8 revision);
+extern int xt_find_revision(int af, const char *name, u8 revision, int target,
+			    int *err);
+
+extern struct xt_table *xt_find_table_lock(int af, const char *name);
+extern void xt_table_unlock(struct xt_table *t);
+
+extern int xt_proto_init(int af);
+extern void xt_proto_fini(int af);
+
+extern struct xt_table_info *xt_alloc_table_info(unsigned int size);
+extern void xt_free_table_info(struct xt_table_info *info);
+
+#endif /* __KERNEL__ */
+
+#endif /* _X_TABLES_H */

include/linux/netfilter/xt_CLASSIFY.h

@@ -0,0 +1,8 @@
+#ifndef _XT_CLASSIFY_H
+#define _XT_CLASSIFY_H
+
+struct xt_classify_target_info {
+	u_int32_t priority;
+};
+
+#endif /*_XT_CLASSIFY_H */

include/linux/netfilter/xt_CONNMARK.h

@@ -0,0 +1,25 @@
+#ifndef _XT_CONNMARK_H_target
+#define _XT_CONNMARK_H_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.
+ */
+
+enum {
+	XT_CONNMARK_SET = 0,
+	XT_CONNMARK_SAVE,
+	XT_CONNMARK_RESTORE
+};
+
+struct xt_connmark_target_info {
+	unsigned long mark;
+	unsigned long mask;
+	u_int8_t mode;
+};
+
+#endif /*_XT_CONNMARK_H_target*/

include/linux/netfilter/xt_MARK.h

@@ -0,0 +1,21 @@
+#ifndef _XT_MARK_H_target
+#define _XT_MARK_H_target
+
+/* Version 0 */
+struct xt_mark_target_info {
+	unsigned long mark;
+};
+
+/* Version 1 */
+enum {
+	XT_MARK_SET=0,
+	XT_MARK_AND,
+	XT_MARK_OR,
+};
+
+struct xt_mark_target_info_v1 {
+	unsigned long mark;
+	u_int8_t mode;
+};
+
+#endif /*_XT_MARK_H_target */

include/linux/netfilter/xt_NFQUEUE.h

@@ -0,0 +1,16 @@
+/* iptables module for using NFQUEUE mechanism
+ *
+ * (C) 2005 Harald Welte <laforge@netfilter.org>
+ *
+ * This software is distributed under GNU GPL v2, 1991
+ * 
+*/
+#ifndef _XT_NFQ_TARGET_H
+#define _XT_NFQ_TARGET_H
+
+/* target info */
+struct xt_NFQ_info {
+	u_int16_t queuenum;
+};
+
+#endif /* _XT_NFQ_TARGET_H */

include/linux/netfilter/xt_comment.h

@@ -0,0 +1,10 @@
+#ifndef _XT_COMMENT_H
+#define _XT_COMMENT_H
+
+#define XT_MAX_COMMENT_LEN 256
+
+struct xt_comment_info {
+	unsigned char comment[XT_MAX_COMMENT_LEN];
+};
+
+#endif /* XT_COMMENT_H */

include/linux/netfilter/xt_connbytes.h

@@ -0,0 +1,25 @@
+#ifndef _XT_CONNBYTES_H
+#define _XT_CONNBYTES_H
+
+enum xt_connbytes_what {
+	XT_CONNBYTES_PKTS,
+	XT_CONNBYTES_BYTES,
+	XT_CONNBYTES_AVGPKT,
+};
+
+enum xt_connbytes_direction {
+	XT_CONNBYTES_DIR_ORIGINAL,
+	XT_CONNBYTES_DIR_REPLY,
+	XT_CONNBYTES_DIR_BOTH,
+};
+
+struct xt_connbytes_info
+{
+	struct {
+		aligned_u64 from;	/* count to be matched */
+		aligned_u64 to;		/* count to be matched */
+	} count;
+	u_int8_t what;		/* ipt_connbytes_what */
+	u_int8_t direction;	/* ipt_connbytes_direction */
+};
+#endif

include/linux/netfilter/xt_connmark.h

@@ -0,0 +1,18 @@
+#ifndef _XT_CONNMARK_H
+#define _XT_CONNMARK_H
+
+/* 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.
+ */
+
+struct xt_connmark_info {
+	unsigned long mark, mask;
+	u_int8_t invert;
+};
+
+#endif /*_XT_CONNMARK_H*/