>> Implement the IOAM egress behavior.
>>
>> According to RFC 8200:
>> "Extension headers (except for the Hop-by-Hop Options header) are not
>> processed, inserted, or deleted by any node along a packet's delivery
>> path, until the packet reaches the node (or each of the set of nodes,
>> in the case of multicast) identified in the Destination Address field
>> of the IPv6 header."
>>
>> Therefore, an ingress node (an IOAM domain border) must encapsulate an
>> incoming IPv6 packet with another similar IPv6 header that will contain
>> IOAM data while it traverses the domain. When leaving, the egress node,
>> another IOAM domain border which is also the tunnel destination, must
>> decapsulate the packet.
>
> This is just IP in IP encapsulation that happens to be terminated at
> an egress node of the IOAM domain. The fact that it's IOAM isn't
> germaine, this IP in IP is done in a variety of ways. We should be
> using the normal protocol handler for NEXTHDR_IPV6 instead of special
> case code.
Agree. The reason for this special case code is that I was not aware of a more
elegant solution.
Justin
>> Signed-off-by: Justin Iurman <justin.iur...@uliege.be>
>> ---
>> include/linux/ipv6.h | 1 +
>> net/ipv6/ip6_input.c | 22 ++++++++++++++++++++++
>> 2 files changed, 23 insertions(+)
>>
>> diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
>> index 2cb445a8fc9e..5312a718bc7a 100644
>> --- a/include/linux/ipv6.h
>> +++ b/include/linux/ipv6.h
>> @@ -138,6 +138,7 @@ struct inet6_skb_parm {
>> #define IP6SKB_HOPBYHOP 32
>> #define IP6SKB_L3SLAVE 64
>> #define IP6SKB_JUMBOGRAM 128
>> +#define IP6SKB_IOAM 256
>> };
>>
>> #if defined(CONFIG_NET_L3_MASTER_DEV)
>> diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
>> index e96304d8a4a7..8cf75cc5e806 100644
>> --- a/net/ipv6/ip6_input.c
>> +++ b/net/ipv6/ip6_input.c
>> @@ -361,9 +361,11 @@ INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff
>> *));
>> void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int
>> nexthdr,
>> bool have_final)
>> {
>> + struct inet6_skb_parm *opt = IP6CB(skb);
>> const struct inet6_protocol *ipprot;
>> struct inet6_dev *idev;
>> unsigned int nhoff;
>> + u8 hop_limit;
>> bool raw;
>>
>> /*
>> @@ -450,6 +452,25 @@ void ip6_protocol_deliver_rcu(struct net *net, struct
>> sk_buff *skb, int nexthdr,
>> } else {
>> if (!raw) {
>> if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
>> + /* IOAM Tunnel Decapsulation
>> + * Packet is going to re-enter the stack
>> + */
>> + if (nexthdr == NEXTHDR_IPV6 &&
>> + (opt->flags & IP6SKB_IOAM)) {
>> + hop_limit = ipv6_hdr(skb)->hop_limit;
>> +
>> + skb_reset_network_header(skb);
>> + skb_reset_transport_header(skb);
>> + skb->encapsulation = 0;
>> +
>> + ipv6_hdr(skb)->hop_limit = hop_limit;
>> + __skb_tunnel_rx(skb, skb->dev,
>> + dev_net(skb->dev));
>> +
>> + netif_rx(skb);
>> + goto out;
>> + }
>> +
>> __IP6_INC_STATS(net, idev,
>> IPSTATS_MIB_INUNKNOWNPROTOS);
>> icmpv6_send(skb, ICMPV6_PARAMPROB,
>> @@ -461,6 +482,7 @@ void ip6_protocol_deliver_rcu(struct net *net, struct
>> sk_buff *skb, int nexthdr,
>> consume_skb(skb);
>> }
>> }
>> +out:
>> return;
>>
>> discard:
>> --
>> 2.17.1
