netfilter: conntrack: udp: fix seen-reply test

IPS_SEEN_REPLY_BIT is only useful for test_bit() api.

Fixes: 4883ec512c17 ("netfilter: conntrack: avoid reload of ct->status")
Reported-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: avoid reload of ct->status

Compiler can't merge the two test_bit() calls, so load ct->status
once and use non-atomic accesses.

This is fine because IPS_EXPECTED or NAT_CLASH are either set at ct
creation time or not at all, but compiler can't know that.

Signed-off-by: Florian Westphal <fw@strlen.de>

Revert "netfilter: conntrack: mark UDP zero checksum as CHECKSUM_UNNECESSARY"

This reverts commit 5bed9f3f63f8f9d2b1758c24640cbf77b5377511.

Gal Presman says:
this patch broke geneve tunnels, or possibly all udp tunnels?
A simple test that creates two geneve tunnels and runs tcp iperf fails
and results in checksum errors (TcpInCsumErrors).

Original commit wanted to fix nf_reject with zero checksum,
so it appears better to change nf reject infra instead.

Fixes: 5bed9f3f63f8f ("netfilter: conntrack: mark UDP zero checksum as CHECKSUM_UNNECESSARY")
Reported-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: mark UDP zero checksum as CHECKSUM_UNNECESSARY

The udp_error function verifies the checksum of incoming UDP packets if
one is set. This has the desirable side effect of setting skb->ip_summed
to CHECKSUM_COMPLETE, signalling that this verification need not be
repeated further up the stack.

Conversely, when the UDP checksum is empty, which is perfectly legal (at least
inside IPv4), udp_error previously left no trace that the checksum had been
deemed acceptable.

This was a problem in particular for nf_reject_ipv4, which verifies the
checksum in nf_send_unreach() before sending ICMP_DEST_UNREACH. It makes
no accommodation for zero UDP checksums unless they are already marked
as CHECKSUM_UNNECESSARY.

This commit ensures packets with empty UDP checksum are marked as
CHECKSUM_UNNECESSARY, which is explicitly recommended in skbuff.h.

Signed-off-by: Kevin Mitchell <kevmitch@arista.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: set on IPS_ASSURED if flows enters internal stream state

The internal stream state sets the timeout to 120 seconds 2 seconds
after the creation of the flow, attach this internal stream state to the
IPS_ASSURED flag for consistent event reporting.

Before this patch:

[NEW] udp 17 30 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 [UNREPLIED] src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282
[UPDATE] udp 17 30 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282
[UPDATE] udp 17 30 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282 [ASSURED]
[DESTROY] udp 17 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282 [ASSURED]

Note IPS_ASSURED for the flow not yet in the internal stream state.

after this update:

[NEW] udp 17 30 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 [UNREPLIED] src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282
[UPDATE] udp 17 30 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282
[UPDATE] udp 17 120 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282 [ASSURED]
[DESTROY] udp 17 src=10.246.11.13 dst=216.239.35.0 sport=37282 dport=123 src=216.239.35.0 dst=10.246.11.13 sport=123 dport=37282 [ASSURED]

Before this patch, short-lived UDP flows never entered IPS_ASSURED, so
they were already candidate flow to be deleted by early_drop under
stress.

Before this patch, IPS_ASSURED is set on regardless the internal stream
state, attach this internal stream state to IPS_ASSURED.

packet #1 (original direction) enters NEW state
packet #2 (reply direction) enters ESTABLISHED state, sets on IPS_SEEN_REPLY
paclet #3 (any direction) sets on IPS_ASSURED (if 2 seconds since the
creation has passed by).

Reported-by: Maciej Żenczykowski <zenczykowski@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove offload_pickup sysctl again

These two sysctls were added because the hardcoded defaults (2 minutes,
tcp, 30 seconds, udp) turned out to be too low for some setups.

They appeared in 5.14-rc1 so it should be fine to remove it again.

Marcelo convinced me that there should be no difference between a flow
that was offloaded vs. a flow that was not wrt. timeout handling.
Thus the default is changed to those for TCP established and UDP stream,
5 days and 120 seconds, respectively.

Marcelo also suggested to account for the timeout value used for the
offloading, this avoids increase beyond the value in the conntrack-sysctl
and will also instantly expire the conntrack entry with altered sysctls.

Example:
nf_conntrack_udp_timeout_stream=60
nf_flowtable_udp_timeout=60

This will remove offloaded udp flows after one minute, rather than two.

An earlier version of this patch also cleared the ASSURED bit to
allow nf_conntrack to evict the entry via early_drop (i.e., table full).
However, it looks like we can safely assume that connection timed out
via HW is still in established state, so this isn't needed.

Quoting Oz:
[..] the hardware sends all packets with a set FIN flags to sw.
[..] Connections that are aged in hardware are expected to be in the
established state.

In case it turns out that back-to-sw-path transition can occur for
'dodgy' connections too (e.g., one side disappeared while software-path
would have been in RETRANS timeout), we can adjust this later.

Cc: Oz Shlomo <ozsh@nvidia.com>
Cc: Paul Blakey <paulb@nvidia.com>
Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: pass hook state to log functions

The packet logger backend is unable to provide the incoming (or
outgoing) interface name because that information isn't available.

Pass the hook state, it contains the network namespace, the protocol
family, the network interfaces and other things.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: Introduce udp offload timeout configuration

UDP connections may be offloaded from nf conntrack to nf flow table.
Offloaded connections are aged after 30 seconds of inactivity.
Once aged, ownership is returned to conntrack with a hard coded pickup
time of 30 seconds, after which the connection may be deleted.
eted. The current aging intervals may be too aggressive for some users.

Provide users with the ability to control the nf flow table offload
aging and pickup time intervals via sysctl parameter as a pre-step for
configuring the nf flow table GC timeout intervals.

Signed-off-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Paul Blakey <paulb@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: do not auto-delete clash entries on reply

Its possible that we have more than one packet with the same ct tuple
simultaneously, e.g. when an application emits n packets on same UDP
socket from multiple threads.

NAT rules might be applied to those packets. With the right set of rules,
n packets will be mapped to m destinations, where at least two packets end
up with the same destination.

When this happens, the existing clash resolution may merge the skb that
is processed after the first has been received with the identical tuple
already in hash table.

However, its possible that this identical tuple is a NAT_CLASH tuple.
In that case the second skb will be sent, but no reply can be received
since the reply that is processed first removes the NAT_CLASH tuple.

Do not auto-delete, this gives a 1 second window for replies to be passed
back to originator.

Packets that are coming later (udp stream case) will not be affected:
they match the original ct entry, not a NAT_CLASH one.

Also prevent NAT_CLASH entries from getting offloaded.

Fixes: 6a757c07e51f ("netfilter: conntrack: allow insertion of clashing entries")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: allow insertion of clashing entries

This patch further relaxes the need to drop an skb due to a clash with
an existing conntrack entry.

Current clash resolution handles the case where the clash occurs between
two identical entries (distinct nf_conn objects with same tuples), i.e.:

Original Reply
existing: 10.2.3.4:42 -> 10.8.8.8:53 10.2.3.4:42 <- 10.0.0.6:5353
clashing: 10.2.3.4:42 -> 10.8.8.8:53 10.2.3.4:42 <- 10.0.0.6:5353

... existing handling will discard the unconfirmed clashing entry and
makes skb->_nfct point to the existing one. The skb can then be
processed normally just as if the clash would not have existed in the
first place.

For other clashes, the skb needs to be dropped.
This frequently happens with DNS resolvers that send A and AAAA queries
back-to-back when NAT rules are present that cause packets to get
different DNAT transformations applied, for example:

-m statistics --mode random ... -j DNAT --dnat-to 10.0.0.6:5353
-m statistics --mode random ... -j DNAT --dnat-to 10.0.0.7:5353

In this case the A or AAAA query is dropped which incurs a costly
delay during name resolution.

This patch also allows this collision type:
Original Reply
existing: 10.2.3.4:42 -> 10.8.8.8:53 10.2.3.4:42 <- 10.0.0.6:5353
clashing: 10.2.3.4:42 -> 10.8.8.8:53 10.2.3.4:42 <- 10.0.0.7:5353

In this case, clash is in original direction -- the reply direction
is still unique.

The change makes it so that when the 2nd colliding packet is received,
the clashing conntrack is tagged with new IPS_NAT_CLASH_BIT, gets a fixed
1 second timeout and is inserted in the reply direction only.

The entry is hidden from 'conntrack -L', it will time out quickly
and it can be early dropped because it will never progress to the
ASSURED state.

To avoid special-casing the delete code path to special case
the ORIGINAL hlist_nulls node, a new helper, "hlist_nulls_add_fake", is
added so hlist_nulls_del() will work.

Example:

CPU A: CPU B:
1. 10.2.3.4:42 -> 10.8.8.8:53 (A)
2. 10.2.3.4:42 -> 10.8.8.8:53 (AAAA)
3. Apply DNAT, reply changed to 10.0.0.6
4. 10.2.3.4:42 -> 10.8.8.8:53 (AAAA)
5. Apply DNAT, reply changed to 10.0.0.7
6. confirm/commit to conntrack table, no collisions
7. commit clashing entry

Reply comes in:

10.2.3.4:42 <- 10.0.0.6:5353 (A)
-> Finds a conntrack, DNAT is reversed & packet forwarded to 10.2.3.4:42
10.2.3.4:42 <- 10.0.0.7:5353 (AAAA)
-> Finds a conntrack, DNAT is reversed & packet forwarded to 10.2.3.4:42
The conntrack entry is deleted from table, as it has the NAT_CLASH
bit set.

In case of a retransmit from ORIGINAL dir, all further packets will get
the DNAT transformation to 10.0.0.6.

I tried to come up with other solutions but they all have worse
problems.

Alternatives considered were:
1. Confirm ct entries at allocation time, not in postrouting.
a. will cause uneccesarry work when the skb that creates the
conntrack is dropped by ruleset.
b. in case nat is applied, ct entry would need to be moved in
the table, which requires another spinlock pair to be taken.
c. breaks the 'unconfirmed entry is private to cpu' assumption:
we would need to guard all nfct->ext allocation requests with
ct->lock spinlock.

2. Make the unconfirmed list a hash table instead of a pcpu list.
Shares drawback c) of the first alternative.

3. Document this is expected and force users to rearrange their
ruleset (e.g. by using "-m cluster" instead of "-m statistics").
nft has the 'jhash' expression which can be used instead of 'numgen'.

Major drawback: doesn't fix what I consider a bug, not very realistic
and I believe its reasonable to have the existing rulesets to 'just
work'.

4. Document this is expected and force users to steer problematic
packets to the same CPU -- this would serialize the "allocate new
conntrack entry/nat table evaluation/perform nat/confirm entry", so
no race can occur. Similar drawback to 3.

Another advantage of this patch compared to 1) and 2) is that there are
no changes to the hot path; things are handled in the udp tracker and
the clash resolution path.

Cc: rcu@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

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

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 #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netfilter: conntrack: remove l4proto init and get_net callbacks

Those were needed we still had modular trackers.
As we don't have those anymore, prefer direct calls and remove all
the (un)register infrastructure associated with this.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: unify sysctl handling

Due to historical reasons, all l4 trackers register their own
sysctls.

This leads to copy&pasted boilerplate code, that does exactly same
thing, just with different data structure.

Place all of this in a single file.

This allows to remove the various ctl_table pointers from the ct_netns
structure and reduces overall code size.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: handle builtin l4proto packet functions via direct calls

The l4 protocol trackers are invoked via indirect call: l4proto->packet().

With one exception (gre), all l4trackers are builtin, so we can make
.packet optional and use a direct call for most protocols.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: udp: set stream timeout to 2 minutes

We have no explicit signal when a UDP stream has terminated, peers just
stop sending.

For suspected stream connections a timeout of two minutes is sane to keep
NAT mapping alive a while longer.

It matches tcp conntracks 'timewait' default timeout value.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: udp: only extend timeout to stream mode after 2s

Currently DNS resolvers that send both A and AAAA queries from same source port
can trigger stream mode prematurely, which results in non-early-evictable conntrack entry
for three minutes, even though DNS requests are done in a few milliseconds.

Add a two second grace period where we continue to use the ordinary
30-second default timeout. Its enough for DNS request/response traffic,
even if two request/reply packets are involved.

ASSURED is still set, else conntrack (and thus a possible
NAT mapping ...) gets zapped too in case conntrack table runs full.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: add nf_{tcp,udp,sctp,icmp,dccp,icmpv6,generic}_pernet()

Expose these functions to access conntrack protocol tracker netns area,
nfnetlink_cttimeout needs this.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove l3->l4 mapping information

l4 protocols are demuxed by l3num, l4num pair.

However, almost all l4 trackers are l3 agnostic.

Only exceptions are:
- gre, icmp (ipv4 only)
- icmpv6 (ipv6 only)

This commit gets rid of the l3 mapping, l4 trackers can now be looked up
by their IPPROTO_XXX value alone, which gets rid of the additional l3
indirection.

For icmp, ipcmp6 and gre, add a check on state->pf and
return -NF_ACCEPT in case we're asked to track e.g. icmpv6-in-ipv4,
this seems more fitting than using the generic tracker.

Additionally we can kill the 2nd l4proto definitions that were needed
for v4/v6 split -- they are now the same so we can use single l4proto
struct for each protocol, rather than two.

The EXPORT_SYMBOLs can be removed as all these object files are
part of nf_conntrack with no external references.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove unused proto arg from netns init functions

Its unused, next patch will remove l4proto->l3proto number to simplify
l4 protocol demuxer lookup.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: deconstify packet callback skb pointer

Only two protocols need the ->error() function: icmp and icmpv6.
This is because icmp error mssages might be RELATED to an existing
connection (e.g. PMTUD, port unreachable and the like), and their
->error() handlers do this.

The error callback is already optional, so remove it for
udp and call them from ->packet() instead.

As the error() callback can call checksum functions that write to
skb->csum*, the const qualifier has to be removed as well.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove the l4proto->new() function

->new() gets invoked after ->error() and before ->packet() if
a conntrack lookup has found no result for the tuple.

We can fold it into ->packet() -- the packet() implementations
can check if the conntrack is confirmed (new) or not
(already in hash).

If its unconfirmed, the conntrack isn't in the hash yet so current
skb created a new conntrack entry.

Only relevant side effect -- if packet() doesn't return NF_ACCEPT
but -NF_ACCEPT (or drop), while the conntrack was just created,
then the newly allocated conntrack is freed right away, rather than not
created in the first place.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: pass nf_hook_state to packet and error handlers

nf_hook_state contains all the hook meta-information: netns, protocol family,
hook location, and so on.

Instead of only passing selected information, pass a pointer to entire
structure.

This will allow to merge the error and the packet handlers and remove
the ->new() function in followup patches.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: timeout interface depend on CONFIG_NF_CONNTRACK_TIMEOUT

Now that cttimeout support for nft_ct is in place, these should depend
on CONFIG_NF_CONNTRACK_TIMEOUT otherwise we can crash when dumping the
policy if this option is not enabled.

[ 71.600121] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[...]
[ 71.600141] CPU: 3 PID: 7612 Comm: nft Not tainted 4.18.0+ #246
[...]
[ 71.600188] Call Trace:
[ 71.600201] ? nft_ct_timeout_obj_dump+0xc6/0xf0 [nft_ct]

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove duplicated include from nf_conntrack_proto_udp.c

Remove duplicated include.

Fixes: c779e849608a ("netfilter: conntrack: remove get_timeout() indirection")
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove get_timeout() indirection

Not needed, we can have the l4trackers fetch it themselvs.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: avoid l4proto pkt_to_tuple calls

Handle common protocols (udp, tcp, ..), in the core and only
do the call if needed by the l4proto tracker.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: avoid calls to l4proto invert_tuple

Handle the common cases (tcp, udp, etc). in the core and only
do the indirect call for the protocols that need it (GRE for instance).

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: timeouts can be const

Nowadays this is just the default template that is used when setting up
the net namespace, so nothing writes to these locations.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: l4 protocol trackers can be const

previous patches removed all writes to these structs so we can
now mark them as const.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove pf argument from l4 packet functions

not needed/used anymore.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: add and use nf_l4proto_log_invalid

We currently pass down the l4 protocol to the conntrack ->packet()
function, but the only user of this is the debug info decision.

Same information can be derived from struct nf_conn.
As a first step, add and use a new log function for this, similar to
nf_ct_helper_log().

Add __cold annotation -- invalid packets should be infrequent so
gcc can consider all call paths that lead to such a function as
unlikely.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: remove unused hooknum arg from packet functions

tested with allmodconfig build.

Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: conntrack: place print_tuple in procfs part

CONFIG_NF_CONNTRACK_PROCFS is deprecated, no need to use a function
pointer in the trackers for this. Place the printf formatting in
the one place that uses it.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: remove protocol name from l4proto struct

no need to waste storage for something that is only needed
in one place and can be deduced from protocol number.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: no need to pass ctinfo to error handler

It is never accessed for reading and the only places that write to it
are the icmp(6) handlers, which also set skb->nfct (and skb->nfctinfo).

The conntrack core specifically checks for attached skb->nfct after
->error() invocation and returns early in this case.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: merge udp and udplite conntrack helpers

udplite was copied from udp, they are virtually 100% identical.

This adds udplite tracker to udp instead, removes udplite module,
and then makes the udplite tracker builtin.

udplite will then simply re-use udp timeout settings.
It makes little sense to add separate sysctls, nowadays we have
fine-grained timeout policy support via the CT target.

old:
text data bss dec hex filename
1633 672 0 2305 901 nf_conntrack_proto_udp.o
1756 672 0 2428 97c nf_conntrack_proto_udplite.o
69526 17937 268 87731 156b3 nf_conntrack.ko

new:
text data bss dec hex filename
2442 1184 0 3626 e2a nf_conntrack_proto_udp.o
68565 17721 268 86554 1521a nf_conntrack.ko

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: remove ip_conntrack* sysctl compat code

This backward compatibility has been around for more than ten years,
since Yasuyuki Kozakai introduced IPv6 in conntrack. These days, we have
alternate /proc/net/nf_conntrack* entries, the ctnetlink interface and
the conntrack utility got adopted by many people in the user community
according to what I observed on the netfilter user mailing list.

So let's get rid of this.

Note that nf_conntrack_htable_size and unsigned int nf_conntrack_max do
not need to be exported as symbol anymore.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: Only need first 4 bytes to get l4proto ports

We only need first 4 bytes instead of 8 bytes to get the ports of
tcp/udp/dccp/sctp/udplite in their pkt_to_tuple function.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: conntrack: introduce clash resolution on insertion race

This patch introduces nf_ct_resolve_clash() to resolve race condition on
conntrack insertions.

This is particularly a problem for connection-less protocols such as
UDP, with no initial handshake. Two or more packets may race to insert
the entry resulting in packet drops.

Another problematic scenario are packets enqueued to userspace via
NFQUEUE after the raw table, that make it easier to trigger this
race.

To resolve this, the idea is to reset the conntrack entry to the one
that won race. Packet and bytes counters are also merged.

The 'insert_failed' stats still accounts for this situation, after
this patch, the drop counter is bumped whenever we drop packets, so we
can watch for unresolved clashes.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_conntrack: Add a struct net parameter to l4_pkt_to_tuple

As gre does not have the srckey in the packet gre_pkt_to_tuple
needs to perform a lookup in it's per network namespace tables.

Pass in the proper network namespace to all pkt_to_tuple
implementations to ensure gre (and any similar protocols) can get this
right.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: Convert print_tuple functions to return void

Since adding a new function to seq_file (seq_has_overflowed())
there isn't any value for functions called from seq_show to
return anything. Remove the int returns of the various
print_tuple/<foo>_print_tuple functions.

Link: http://lkml.kernel.org/p/f2e8cf8df433a197daa62cbaf124c900c708edc7.1412031505.git.joe@perches.com

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: netfilter-devel@vger.kernel.org
Cc: coreteam@netfilter.org
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

netfilter: add my copyright statements

Add copyright statements to all netfilter files which have had significant
changes done by myself in the past.

Some notes:

- nf_conntrack_ecache.c was incorrectly attributed to Rusty and Netfilter
Core Team when it got split out of nf_conntrack_core.c. The copyrights
even state a date which lies six years before it was written. It was
written in 2005 by Harald and myself.

- net/ipv{4,6}/netfilter.c, net/netfitler/nf_queue.c were missing copyright
statements. I've added the copyright statement from net/netfilter/core.c,
where this code originated

- for nf_conntrack_proto_tcp.c I've also added Jozsef, since I didn't want
it to give the wrong impression

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_log: prepare net namespace support for loggers

This patch adds netns support to nf_log and it prepares netns
support for existing loggers. It is composed of four major
changes.

1) nf_log_register has been split to two functions: nf_log_register
and nf_log_set. The new nf_log_register is used to globally
register the nf_logger and nf_log_set is used for enabling
pernet support from nf_loggers.

Per netns is not yet complete after this patch, it comes in
separate follow up patches.

2) Add net as a parameter of nf_log_bind_pf. Per netns is not
yet complete after this patch, it only allows to bind the
nf_logger to the protocol family from init_net and it skips
other cases.

3) Adapt all nf_log_packet callers to pass netns as parameter.
After this patch, this function only works for init_net.

4) Make the sysctl net/netfilter/nf_log pernet.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_conntrack: generalize nf_ct_l4proto_net

This patch generalizes nf_ct_l4proto_net by splitting it into chunks and
moving the corresponding protocol part to where it really belongs to.

To clarify, note that we follow two different approaches to support per-net
depending if it's built-in or run-time loadable protocol tracker.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Gao feng <gaofeng@cn.fujitsu.com>

netfilter: nf_ct_udp: merge udpv[4,6]_net_init into udp_net_init

Merge udpv4_net_init and udpv6_net_init into udp_net_init to
remove redundant code now that we have the u_int16_t proto
parameter.

And use nf_proto_net.users to identify if it's the first time
we use the nf_proto_net, in that case, we initialize it.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_conntrack: prepare l4proto->init_net cleanup

l4proto->init contain quite redundant code. We can simplify this
by adding a new parameter l3proto.

This patch prepares that code simplification.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_ct_tcp, udp: fix compilation with sysctl disabled

This patch fixes the compilation of the TCP and UDP trackers with sysctl
compilation disabled:

net/netfilter/nf_conntrack_proto_udp.c: In function ‘udp_init_net_data’:
net/netfilter/nf_conntrack_proto_udp.c:279:13: error: ‘struct nf_proto_net’ has no member named
‘user’
net/netfilter/nf_conntrack_proto_tcp.c:1606:9: error: ‘struct nf_proto_net’ has no member named
‘user’
net/netfilter/nf_conntrack_proto_tcp.c:1643:9: error: ‘struct nf_proto_net’ has no member named
‘user’

Reported-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: nf_conntrack: add namespace support for cttimeout

This patch adds namespace support for cttimeout.

Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_conntrack: remove now unused sysctl for nf_conntrack_l[3|4]proto

Since the sysctl data for l[3|4]proto now resides in pernet nf_proto_net.
We can now remove this unused fields from struct nf_contrack_l[3,4]proto.

Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_ct_udp: add namespace support

This patch adds namespace support for UDP protocol tracker.

Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_conntrack_proto_udp{,lite}: Stop using NLA_PUT*().

These macros contain a hidden goto, and are thus extremely error
prone and make code hard to audit.

Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: add cttimeout infrastructure for fine timeout tuning

This patch adds the infrastructure to add fine timeout tuning
over nfnetlink. Now you can use the NFNL_SUBSYS_CTNETLINK_TIMEOUT
subsystem to create/delete/dump timeout objects that contain some
specific timeout policy for one flow.

The follow up patches will allow you attach timeout policy object
to conntrack via the CT target and the conntrack extension
infrastructure.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_conntrack: pass timeout array to l4->new and l4->packet

This patch defines a new interface for l4 protocol trackers:

unsigned int *(*get_timeouts)(struct net *net);

that is used to return the array of unsigned int that contains
the timeouts that will be applied for this flow. This is passed
to the l4proto->new(...) and l4proto->packet(...) functions to
specify the timeout policy.

This interface allows per-net global timeout configuration
(although only DCCP supports this by now) and it will allow
custom custom timeout configuration by means of follow-up
patches.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_ct_udp[lite]: convert UDP[lite] timeouts to array

Use one array to store the UDP timeouts instead of two variables.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net:netfilter: use IS_ENABLED

Use IS_ENABLED(CONFIG_FOO)
instead of defined(CONFIG_FOO) || defined (CONFIG_FOO_MODULE)

Signed-off-by: Igor Maravić <igorm@etf.rs>
Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: nf_conntrack: pass template to l4proto ->error() handler

The error handlers might need the template to get the conntrack zone
introduced in the next patches to perform a conntrack lookup.

Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: nf_conntrack: split up IPCT_STATUS event

Split up the IPCT_STATUS event into an IPCT_REPLY event, which is generated
when the IPS_SEEN_REPLY bit is set, and an IPCT_ASSURED event, which is
generated when the IPS_ASSURED bit is set.

In combination with a following patch to support selective event delivery,
this can be used for "sparse" conntrack replication: start replicating the
conntrack entry after it reached the ASSURED state and that way it's SYN-flood
resistant.

Signed-off-by: Patrick McHardy <kaber@trash.net>

sysctl net: Remove unused binary sysctl code

Now that sys_sysctl is a compatiblity wrapper around /proc/sys
all sysctl strategy routines, and all ctl_name and strategy
entries in the sysctl tables are unused, and can be
revmoed.

In addition neigh_sysctl_register has been modified to no longer
take a strategy argument and it's callers have been modified not
to pass one.

Cc: "David Miller" <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

netfilter: nf_conntrack: calculate per-protocol nlattr size

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: remove IPvX specific parts from nf_conntrack_l4proto.h

Moving the structure definitions to the corresponding IPvX specific header files.

Signed-off-by: Patrick McHardy <kaber@trash.net>

net: '&' redux

I want to compile out proc_* and sysctl_* handlers totally and
stub them to NULL depending on config options, however usage of &
will prevent this, since taking adress of NULL pointer will break
compilation.

So, drop & in front of every ->proc_handler and every ->strategy
handler, it was never needed in fact.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: netns nf_conntrack: per-netns net.netfilter.nf_conntrack_log_invalid sysctl

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: netns nf_conntrack: per-netns net.netfilter.nf_conntrack_checksum sysctl

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: netns nf_conntrack: pass conntrack to nf_conntrack_event_cache() not skb

This is cleaner, we already know conntrack to which event is relevant.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: netns nf_conntrack: pass netns pointer to L4 protocol's ->error hook

Again, it's deducible from skb, but we're going to use it for
nf_conntrack_checksum and statistics, so just pass it from upper layer.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

netfilter: Use unsigned types for hooknum and pf vars

and (try to) consistently use u_int8_t for the L3 family.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: nf_conntrack: use bool type in struct nf_conntrack_l4proto

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: nf_{conntrack,nat}_proto_udp{,lite}: annotate with const

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: naming unification

Rename all "conntrack" variables to "ct" for more consistency and
avoiding some overly long lines.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: make print_conntrack function optional for l4protos

Allows to remove five empty implementations.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_log: move logging stuff to seperate header

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Introduce NF_INET_ hook values

The IPv4 and IPv6 hook values are identical, yet some code tries to figure
out the "correct" value by looking at the address family. Introduce NF_INET_*
values for both IPv4 and IPv6. The old values are kept in a #ifndef __KERNEL__
section for userspace compatibility.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

sysctl: remove broken netfilter binary sysctls

No one has bothered to set strategy routine for the the netfilter sysctls that
return jiffies to be sysctl_jiffies.

So it appears the sys_sysctl path is unused and untested, so this patch
removes the binary sysctl numbers.

Which fixes the netfilter oops in 2.6.23-rc2-mm2 for me.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[NETFILTER]: ctnetlink: use netlink policy

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nfnetlink: rename functions containing 'nfattr'

There is no struct nfattr anymore, rename functions to 'nlattr'.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Clean up duplicate includes in net/netfilter/

This patch cleans up duplicate includes in
net/netfilter/

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: mark protocols __read_mostly

Also remove two unnecessary EXPORT_SYMBOLs and move the
nf_conntrack_l3proto_ipv4 declaration to the correct file.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Remove changelogs and CVS IDs

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack/nf_nat: fix incorrect config ifdefs

The nf_conntrack_netlink config option is named CONFIG_NF_CT_NETLINK,
but multiple files use CONFIG_IP_NF_CONNTRACK_NETLINK or
CONFIG_NF_CONNTRACK_NETLINK for ifdefs.

Fix this and reformat all CONFIG_NF_CT_NETLINK ifdefs to only use a line.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[PATCH] remove many unneeded #includes of sched.h

After Al Viro (finally) succeeded in removing the sched.h #include in module.h
recently, it makes sense again to remove other superfluous sched.h includes.
There are quite a lot of files which include it but don't actually need
anything defined in there. Presumably these includes were once needed for
macros that used to live in sched.h, but moved to other header files in the
course of cleaning it up.

To ease the pain, this time I did not fiddle with any header files and only
removed #includes from .c-files, which tend to cause less trouble.

Compile tested against 2.6.20-rc2 and 2.6.20-rc2-mm2 (with offsets) on alpha,
arm, i386, ia64, mips, powerpc, and x86_64 with allnoconfig, defconfig,
allmodconfig, and allyesconfig as well as a few randconfigs on x86_64 and all
configs in arch/arm/configs on arm. I also checked that no new warnings were
introduced by the patch (actually, some warnings are removed that were emitted
by unnecessarily included header files).

Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[NETFILTER]: nf_conntrack: EXPORT_SYMBOL cleanup

- move EXPORT_SYMBOL next to exported symbol
- use EXPORT_SYMBOL_GPL since this is what the original code used

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: sysctl compatibility with old connection tracking

This patch adds an option to keep the connection tracking sysctls visible
under their old names.

Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: nf_conntrack: move conntrack protocol sysctls to individual modules

Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: nf_conntrack: rename struct nf_conntrack_protocol

Rename 'struct nf_conntrack_protocol' to 'struct nf_conntrack_l4proto' in
order to help distinguish it from 'struct nf_conntrack_l3proto'. It gets
rather confusing with 'nf_conntrack_protocol'.

Signed-off-by: Martin Josefsson <gandalf@wlug.westbo.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: nf_conntrack: split out the event cache

This patch splits out the event cache into its own file
nf_conntrack_ecache.c

Signed-off-by: Martin Josefsson <gandalf@wlug.westbo.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>

[NETFILTER]: Change tunables to __read_mostly

Change some netfilter tunables to __read_mostly. Also fixed some
incorrect file reference comments while I was in there.

(this will be my last __read_mostly patch unless someone points out
something else that needs it)

Signed-off-by: Brian Haley <brian.haley@hp.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NET]: Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETE

Replace CHECKSUM_HW by CHECKSUM_PARTIAL (for outgoing packets, whose
checksum still needs to be completed) and CHECKSUM_COMPLETE (for
incoming packets, device supplied full checksum).

Patch originally from Herbert Xu, updated by myself for 2.6.18-rc3.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: conntrack: add sysctl to disable checksumming

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Convert conntrack/ipt_REJECT to new checksumming functions

Besides removing lots of duplicate code, all converted users benefit
from improved HW checksum error handling. Tested with and without HW
checksums in almost all combinations.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: nf_conntrack: Fix TCP/UDP HW checksum handling for IPv6 packet

If skb->ip_summed is CHECKSUM_HW here, skb->csum includes checksum
of actual IPv6 header and extension headers. Then such excess
checksum must be subtruct when nf_conntrack calculates TCP/UDP checksum
with pseudo IPv6 header. Spotted by Ben Skeggs.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Fix timeout sysctls on big-endian 64bit architectures

The connection tracking timeout variables are unsigned long, but
proc_dointvec_jiffies is used with sizeof(unsigned int) in the sysctl
tables. Since there is no proc_doulongvec_jiffies function, change the
timeout variables to unsigned int.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[NETFILTER]: Add ctnetlink port for nf_conntrack

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[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>