Description From the RFC:
The Main Reasons:
o To allow SCTP traffic to pass through legacy NATs, which do not
provide native SCTP support as specified in [BEHAVE] and
[NATSUPP].
o To allow SCTP to be implemented on hosts that do not provide
direct access to the IP layer. In particular, applications can
use their own SCTP implementation if the operating system does not
provide one.
Implementation Notes:
UDP-encapsulated SCTP is normally communicated between SCTP stacks
using the IANA-assigned UDP port number 9899 (sctp-tunneling) on both
ends. There are circumstances where other ports may be used on
either end, and it might be required to use ports other than the
registered port.
Each SCTP stack uses a single local UDP encapsulation port number as
the destination port for all its incoming SCTP packets, this greatly
simplifies implementation design.
An SCTP implementation supporting UDP encapsulation MUST maintain a
remote UDP encapsulation port number per destination address for each
SCTP association. Again, because the remote stack may be using ports
other than the well-known port, each port may be different from each
stack. However, because of remapping of ports by NATs, the remote
ports associated with different remote IP addresses may not be
identical, even if they are associated with the same stack.
Because the well-known port might not be used, implementations need
to allow other port numbers to be specified as a local or remote UDP
encapsulation port number through APIs.
Patches:
This patchset is using the udp4/6 tunnel APIs to implement the UDP
Encapsulation of SCTP with not much change in SCTP protocol stack
and with all current SCTP features keeped in Linux Kernel.
1 - 4: Fix some UDP issues that may be triggered by SCTP over UDP.
5 - 7: Process incoming UDP encapsulated packets and ICMP packets.
8 -10: Remote encap port's update by sysctl, sockopt and packets.
11-14: Process outgoing pakects with UDP encapsulated and its GSO.
15: Enable this feature.
Tests:
- lksctp-tools/src/func_tests with UDP Encapsulation enabled/disabled:
Both make v4test and v6test passed.
- sctp-tests with UDP Encapsulation enabled/disabled:
repeatability/procdumps/sctpdiag/gsomtuchange/extoverflow/
sctphashtable passed. Others failed as expected due to those
"iptables -p sctp" rules.
- netperf on lo/netns/virtio_net, with gso enabled/disabled and
with ip_checksum enabled/disabled, with UDP Encapsulation
enabled/disabled:
No clear performance dropped.
Xin Long (15):
udp: check udp sock encap_type in __udp_lib_err
udp6: move the mss check after udp gso tunnel processing
udp: do checksum properly in skb_udp_tunnel_segment
udp: support sctp over udp in skb_udp_tunnel_segment
sctp: create udp4 sock and add its encap_rcv
sctp: create udp6 sock and set its encap_rcv
sctp: add encap_err_lookup for udp encap socks
sctp: add encap_port for netns sock asoc and transport
sctp: add SCTP_REMOTE_UDP_ENCAPS_PORT sockopt
sctp: allow changing transport encap_port by peer packets
sctp: add udphdr to overhead when udp_port is set
sctp: call sk_setup_caps in sctp_packet_transmit instead
sctp: support for sending packet over udp4 sock
sctp: support for sending packet over udp6 sock
sctp: enable udp tunneling socks
include/net/netns/sctp.h | 8 +++
include/net/sctp/constants.h | 2 +
include/net/sctp/sctp.h | 9 ++-
include/net/sctp/sm.h | 1 +
include/net/sctp/structs.h | 13 ++--
include/uapi/linux/sctp.h | 7 ++
net/ipv4/udp.c | 2 +-
net/ipv4/udp_offload.c | 16 +++--
net/ipv6/udp.c | 2 +-
net/ipv6/udp_offload.c | 154 +++++++++++++++++++++----------------------
net/sctp/associola.c | 4 ++
net/sctp/ipv6.c | 48 ++++++++++----
net/sctp/output.c | 22 +++----
net/sctp/protocol.c | 145 ++++++++++++++++++++++++++++++++++++----
net/sctp/sm_make_chunk.c | 1 +
net/sctp/sm_statefuns.c | 2 +
net/sctp/socket.c | 111 +++++++++++++++++++++++++++++++
net/sctp/sysctl.c | 53 +++++++++++++++
18 files changed, 471 insertions(+), 129 deletions(-)
--
2.1.0
