netfilter: built-in conntrack support for DCCP, SCTP, UDPlite

When netfilter needs to match traffic made by one of the above protocols, layer-4 connection tracking functionality will not be available, unless the user explicly loads it in the kernel (e.g. "modprobe nf_conntrack_proto_sctp") or modifies the default kernel configuration and rebuilds.
In order to remove such limitation, this series converts CONFIG_NF_CT_PROTO_{DCCP,SCTP,UDPLITE} from tristate to boolean: in case conntrack support for these protocols is enabled in the kernel configuration, it will be built into nf_conntrack.ko.

Patch 1/4 fixes nf_conntrack_tuple_common.h to avoid compile-time errors when moving module per-net private data.
Patches 2/4 3,4 and 4/4 remove loadable kernel module support from DCCP, SCTP and UDPlite respectively.

footprint test (nf-next.git, x86_64, RHEL7)

Patches 2/4 to 4/4 in this series have been individually tested on a nf-next.git kernel with standard RHEL7 configuration on x86_64 architecture, recording the unstripped binary size after module clean/rebuild:

$ ls -l net/netfilter/nf_conntrack{,_proto_{dccp,sctp,udplite}}.ko \
        net/ipv4/netfilter/nf_conntrack_ipv4.ko \
        net/ipv6/netfilter/nf_conntrack_ipv6.ko

(builtin)|| dccp | sctp | udplite | ipv4 | ipv6 | nf_conntrack
---------++--------+--------+-----------+--------+--------+--------------

none     || 469140 | 498243 |  432538   | 828755 | 828676 | 6141434
DCCP     ||   -    | 498987 |  432746   | 830566 | 829935 | 6533526
SCTP     || 469276 |   -    |  432690   | 829254 | 829175 | 6547872
UDPlite  || 469484 | 498587 |    -      | 829649 | 829362 | 6498204
all      ||   -    |   -    |    -      | 831999 | 831104 | 7298358

v2:
- patch 1/4: use #ifndef __KERNEL__ directive instead of just removing "#include <linux/netfilter.h>" line
- patch 1/4: reword commit message

Davide Caratti (4):
netfilter: nf_conntrack_tuple_common.h: fix #include
netfilter: conntrack: built-in support for DCCP
netfilter: conntrack: built-in support for SCTP
netfilter: conntrack: built-in support for UDPlite

 include/linux/netfilter/nf_conntrack_dccp.h        |  2 +-
 include/net/netfilter/ipv4/nf_conntrack_ipv4.h     |  9 +++
 include/net/netfilter/ipv6/nf_conntrack_ipv6.h     |  9 +++
 include/net/netns/conntrack.h                      | 43 ++++++++++++
 .../linux/netfilter/nf_conntrack_tuple_common.h    |  3 +
 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c     |  9 +++
 net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c     |  9 +++
 net/netfilter/Kconfig                              | 18 ++---
 net/netfilter/Makefile                             |  7 +-
 net/netfilter/nf_conntrack_proto_dccp.c            | 79 +++-------------------
 net/netfilter/nf_conntrack_proto_sctp.c            | 76 +++------------------
 net/netfilter/nf_conntrack_proto_udplite.c         | 79 +++-------------------
 12 files changed, 123 insertions(+), 220 deletions(-)

2.7.4