[NETFILTER]: Add nf_conntrack subsystem.

The existing connection tracking subsystem in netfilter can only
handle ipv4.  There were basically two choices present to add
connection tracking support for ipv6.  We could either duplicate all
of the ipv4 connection tracking code into an ipv6 counterpart, or (the
choice taken by these patches) we could design a generic layer that
could handle both ipv4 and ipv6 and thus requiring only one sub-protocol
(TCP, UDP, etc.) connection tracking helper module to be written.

In fact nf_conntrack is capable of working with any layer 3
protocol.

The existing ipv4 specific conntrack code could also not deal
with the pecularities of doing connection tracking on ipv6,
which is also cured here.  For example, these issues include:

1) ICMPv6 handling, which is used for neighbour discovery in
   ipv6 thus some messages such as these should not participate
   in connection tracking since effectively they are like ARP
   messages

2) fragmentation must be handled differently in ipv6, because
   the simplistic "defrag, connection track and NAT, refrag"
   (which the existing ipv4 connection tracking does) approach simply
   isn't feasible in ipv6

3) ipv6 extension header parsing must occur at the correct spots
   before and after connection tracking decisions, and there were
   no provisions for this in the existing connection tracking
   design

4) ipv6 has no need for stateful NAT

The ipv4 specific conntrack layer is kept around, until all of
the ipv4 specific conntrack helpers are ported over to nf_conntrack
and it is feature complete.  Once that occurs, the old conntrack
stuff will get placed into the feature-removal-schedule and we will
fully kill it off 6 months later.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

1 files changed, 31 insertions, 10 deletions

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 7d917e4ce1d9..9d3c8b5f327e 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -5,6 +5,20 @@
 menu "IP: Netfilter Configuration"
 	depends on INET && NETFILTER
 
+config NF_CONNTRACK_IPV4
+	tristate "IPv4 support for new connection tracking (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	---help---
+	  Connection tracking keeps a record of what packets have passed
+	  through your machine, in order to figure out how they are related
+	  into connections.
+
+	  This is IPv4 support on Layer 3 independent connection tracking.
+	  Layer 3 independent connection tracking is experimental scheme
+	  which generalize ip_conntrack to support other layer 3 protocols.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
 # connection tracking, helpers and protocols
 config IP_NF_CONNTRACK
 	tristate "Connection tracking (required for masq/NAT)"
@@ -209,8 +223,8 @@ config IP_NF_MATCH_PKTTYPE
 	tristate "Packet type match support"
 	depends on IP_NF_IPTABLES
 	help
-         Packet type matching allows you to match a packet by
-         its "class", eg. BROADCAST, MULTICAST, ...
+	  Packet type matching allows you to match a packet by
+	  its "class", eg. BROADCAST, MULTICAST, ...
 
 	  Typical usage:
 	  iptables -A INPUT -m pkttype --pkt-type broadcast -j LOG
@@ -317,7 +331,8 @@ config IP_NF_MATCH_TCPMSS
 
 config IP_NF_MATCH_HELPER
 	tristate "Helper match support"
-	depends on IP_NF_CONNTRACK && IP_NF_IPTABLES
+	depends on IP_NF_IPTABLES
+	depends on IP_NF_CONNTRACK || NF_CONNTRACK_IPV4
 	help
 	  Helper matching allows you to match packets in dynamic connections
 	  tracked by a conntrack-helper, ie. ip_conntrack_ftp
@@ -326,7 +341,8 @@ config IP_NF_MATCH_HELPER
 
 config IP_NF_MATCH_STATE
 	tristate "Connection state match support"
-	depends on IP_NF_CONNTRACK && IP_NF_IPTABLES
+	depends on IP_NF_IPTABLES
+	depends on IP_NF_CONNTRACK || NF_CONNTRACK_IPV4
 	help
 	  Connection state matching allows you to match packets based on their
 	  relationship to a tracked connection (ie. previous packets).  This
@@ -336,7 +352,8 @@ config IP_NF_MATCH_STATE
 
 config IP_NF_MATCH_CONNTRACK
 	tristate "Connection tracking match support"
-	depends on IP_NF_CONNTRACK && IP_NF_IPTABLES
+	depends on IP_NF_IPTABLES
+	depends on IP_NF_CONNTRACK || NF_CONNTRACK_IPV4
 	help
 	  This is a general conntrack match module, a superset of the state match.
 
@@ -422,7 +439,8 @@ config IP_NF_MATCH_COMMENT
 
 config IP_NF_MATCH_CONNMARK
 	tristate  'Connection mark match support'
-	depends on IP_NF_CONNTRACK_MARK && IP_NF_IPTABLES
+	depends on IP_NF_IPTABLES
+	depends on IP_NF_CONNTRACK_MARK || (NF_CONNTRACK_MARK && NF_CONNTRACK_IPV4)
 	help
 	  This option adds a `connmark' match, which allows you to match the
 	  connection mark value previously set for the session by `CONNMARK'. 
@@ -433,7 +451,8 @@ config IP_NF_MATCH_CONNMARK
 
 config IP_NF_MATCH_CONNBYTES
 	tristate  'Connection byte/packet counter match support'
-	depends on IP_NF_CT_ACCT && IP_NF_IPTABLES
+	depends on IP_NF_IPTABLES
+	depends on IP_NF_CT_ACCT || (NF_CT_ACCT && NF_CONNTRACK_IPV4)
 	help
 	  This option adds a `connbytes' match, which allows you to match the
 	  number of bytes and/or packets for each direction within a connection.
@@ -747,7 +766,8 @@ config IP_NF_TARGET_TTL
 
 config IP_NF_TARGET_CONNMARK
 	tristate  'CONNMARK target support'
-	depends on IP_NF_CONNTRACK_MARK && IP_NF_MANGLE
+	depends on IP_NF_MANGLE
+	depends on IP_NF_CONNTRACK_MARK || (NF_CONNTRACK_MARK && NF_CONNTRACK_IPV4)
 	help
 	  This option adds a `CONNMARK' target, which allows one to manipulate
 	  the connection mark value.  Similar to the MARK target, but
@@ -759,7 +779,8 @@ config IP_NF_TARGET_CONNMARK
 
 config IP_NF_TARGET_CLUSTERIP
 	tristate "CLUSTERIP target support (EXPERIMENTAL)"
-	depends on IP_NF_CONNTRACK_MARK && IP_NF_IPTABLES && EXPERIMENTAL
+	depends on IP_NF_IPTABLES && EXPERIMENTAL
+	depends on IP_NF_CONNTRACK_MARK || (NF_CONNTRACK_MARK && NF_CONNTRACK_IPV4)
 	help
 	  The CLUSTERIP target allows you to build load-balancing clusters of
 	  network servers without having a dedicated load-balancing
@@ -782,7 +803,7 @@ config IP_NF_RAW
 config IP_NF_TARGET_NOTRACK
 	tristate  'NOTRACK target support'
 	depends on IP_NF_RAW
-	depends on IP_NF_CONNTRACK
+	depends on IP_NF_CONNTRACK || NF_CONNTRACK_IPV4
 	help
 	  The NOTRACK target allows a select rule to specify
 	  which packets *not* to enter the conntrack/NAT