On Wed, Mar 28, 2018 at 9:52 AM, Eelco Chaudron <echau...@redhat.com> wrote:
> On 03/09/2018 03:59 PM, William Tu wrote:
>>
>> On Thu, Feb 8, 2018 at 10:42 AM, Eric Garver <e...@erig.me> wrote:
>>>
>>> On Thu, Feb 08, 2018 at 04:40:38PM +0100, Eelco Chaudron wrote:
>>>>
>>>> While OVS userspace datapath (OVS-DPDK) supports GREv6, it does not
>>>> inter-operate with a native Linux ip6gretap tunnel. This is because
>>>> the Linux driver uses IPv6 optional headers for the Tunnel
>>>> Encapsulation Limit (RFC 2473, section 6.6).
>>>
>>> Maybe worth noting that the kernel started adding these headers in
>>> 4.12. Specifically, it was introduced by 89a23c8b528b ("ip6_tunnel: Fix
>>> missing tunnel encapsulation limit option")
>>>
>>>> OVS userspace simply does not parse these IPv6 extension headers
>>>> inside netdev_tnl_ip_extract_tnl_md(), as such popping the tunnel
>>>> leaves extra bytes resulting in a mangled decapsulated frame.
>>>>
>>>> The change below will parse the IPv6 "next header" chain and return
>>>> the offset to the upper layer protocol.
>>>>
>>>> v1->v2
>>>> - Remove netdev_tnl_ip6_get_upperlayer_offset() and reused existing
>>>> parse_ipv6_ext_hdrs() function.
>>>>
>> I also hit this issue recent. I tested this patch and it works OK.
>> However, do you think its simpler if we do below:
>> --- a/lib/netdev-native-tnl.c
>> +++ b/lib/netdev-native-tnl.c
>> @@ -146,8 +146,8 @@ netdev_tnl_ip_extract_tnl_md(struct dp_packet
>> *packet, struct flow_tnl *tnl,
>> tnl->ip_tos = ntohl(tc_flow) >> 20;
>> tnl->ip_ttl = ip6->ip6_hlim;
>>
>> - *hlen += IPV6_HEADER_LEN;
>> + *hlen += packet->l4_ofs - packet->l3_ofs;
>>
>> Since parse_ipv6_ext_hdrs() already called at packet parsing stage,
>> the l4_ofs has the extension header's length.
>
> Are you sure this path is taken for all packets? Quickly looking at the code
> I see this path only with connection tracking actions. Or did I miss
> something?
>
in the miniflow_extract, it calls
parse_ipv6_ext_hdrs__(&data, &size, &nw_proto, &nw_frag)
so the 'size' is updated with the ipv6 extension length.
William
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