ipv6: implement dataplane support for rthdr type 4 (Segment Routing Header)

Implement minimal support for processing of SR-enabled packets
as described in
https://tools.ietf.org/html/draft-ietf-6man-segment-routing-header-02.

This patch implements the following operations:
- Intermediate segment endpoint: incrementation of active segment and rerouting.
- Egress for SR-encapsulated packets: decapsulation of outer IPv6 header + SRH
  and routing of inner packet.
- Cleanup flag support for SR-inlined packets: removal of SRH if we are the
  penultimate segment endpoint.

A per-interface sysctl seg6_enabled is provided, to accept/deny SR-enabled
packets. Default is deny.

This patch does not provide support for HMAC-signed packets.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 1afb6e8d35c3..68d3f71f0abf 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -64,6 +64,7 @@ struct ipv6_devconf {
 	} stable_secret;
 	__s32		use_oif_addrs_only;
 	__s32		keep_addr_on_down;
+	__s32		seg6_enabled;
 
 	struct ctl_table_header *sysctl_header;
 };