On Wed, Nov 19, 2025 at 12:35:54PM +0200, Junfeng Guo wrote:
> The HWS (Hardware Steering) IP tunnel detection implementation was not
> recognizing IPIP tunnel types based on the next protocol value in the
> outer IP header as specified by RFC 2003 (IP-in-IP) and RFC 2473
> (IPv6 Encapsulation).
>
> The issue was that the code treated all combinations of [IPv4|6] / [IPv4|6]
> as IPIP tunnels, setting MLX5_FLOW_LAYER_IPIP flag regardless of the actual
> protocol. While this happened to work for simple cases due to the fallback
> classification, it violated RFC compliance and could cause issues with
> protocol validation.
>
> The fix adds RFC-compliant tunnel detection by
> 1. Checking the protocol field (IPPROTO_IPIP=4 or IPPROTO_IPV6=41) in the
> outer IP header to determine tunnel type
> 2. Adding protocol mismatch validation to ensure outer protocol matches
> inner header type
> 3. Correctly setting MLX5_FLOW_LAYER_IPV6_ENCAP for IPv6 encapsulation
>
> The expected tunnel patterns are now:
> - [ipv4 | ipv6] proto is 4 / ipv4 -> MLX5_FLOW_LAYER_IPIP
> - [ipv4 | ipv6] proto is 41 / ipv6 -> MLX5_FLOW_LAYER_IPV6_ENCAP
>
> For cases without protocol specification, fallback classification based on
> inner header type is still supported.
>
> Fixes: f66c7c3ab983 ("net/mlx5/hws: recognize IP-in-IP tunnel in definer
> layer")
> Fixes: 4b7044562f59 ("net/mlx5: support IP-in-IP tunnel for all combinations")
> Cc: [email protected]
>
> Signed-off-by: Junfeng Guo <[email protected]>
Acked-by: Dariusz Sosnowski <[email protected]>
Best regards,
Dariusz Sosnowski
