[PATCH] net/rte_net: fix inner L2 length for tunneled Ethernet packets

[Ivan Malov]

Hi,

On Mon, 28 Jul 2025, Khadem Ullah wrote:

> Fix incorrect inner_l2_len values for VXLAN, VXLAN-GPE, GTPU, and Geneve.
> These protocols carry full Ethernet frames, so inner_l2_len should be
> set to the size of an Ethernet header (14 bytes), not include tunnel or
> UDP headers.

Does the bug break 'testpmd' (see 'inner_l2_len' over there) or what? How can
this be reproduced?

Also, how well does the patch agree with what is currently said in 'rte_net.h'?

>	/* Outer_L4_len + ... + inner L2_len for tunneling pkt. */
>	uint8_t inner_l2_len;

Is the comment also wrong or do we have a fundamental confusion in DPDK?

I know, for example, that in mbufs, in the case of a tunneled (VXLAN) packet,
fields 'outer_l2_len' and 'outer_l3_len' are Ethernet and IP sizes respectively,
whilst 'l2_len' is a sum of the UDP size, VXLAN size and inner Ethernet header.
But that's in mbuf, which does not have a separate 'tunnel_len' field.

So either there's some confusion, or the patch also needs to fix other places,
such as the header file mentioned ('rte_net.h').

Thank you.


>
> Fixes: 64ed7f854c ('net: add tunnel packet type parsing')
> Cc: stable at dpdk.org
>
> Signed-off-by: Khadem Ullah <14pwcse1224 at uetpeshawar.edu.pk>
> ---
> lib/net/rte_net.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/lib/net/rte_net.c b/lib/net/rte_net.c
> index 44fb6c0f51..adcddeb670 100644
> --- a/lib/net/rte_net.c
> +++ b/lib/net/rte_net.c
> @@ -198,7 +198,7 @@ ptype_tunnel_with_udp(uint16_t *proto, const struct rte_mbuf *m,
> 	case RTE_VXLAN_DEFAULT_PORT: {
> 		*off += sizeof(struct rte_vxlan_hdr);
> 		hdr_lens->tunnel_len = sizeof(struct rte_vxlan_hdr);
> -		hdr_lens->inner_l2_len = RTE_ETHER_VXLAN_HLEN;
> +		hdr_lens->inner_l2_len = sizeof(struct rte_ether_hdr);
> 		*proto = RTE_VXLAN_GPE_TYPE_ETH; /* just for eth header parse. */
> 		return RTE_PTYPE_TUNNEL_VXLAN;
> 	}
> @@ -210,7 +210,7 @@ ptype_tunnel_with_udp(uint16_t *proto, const struct rte_mbuf *m,
> 			return 0;
> 		*off += sizeof(struct rte_vxlan_gpe_hdr);
> 		hdr_lens->tunnel_len = sizeof(struct rte_vxlan_gpe_hdr);
> -		hdr_lens->inner_l2_len = RTE_ETHER_VXLAN_GPE_HLEN;
> +		hdr_lens->inner_l2_len = sizeof(struct rte_ether_hdr);
> 		*proto = vgh->proto;
>
> 		return RTE_PTYPE_TUNNEL_VXLAN_GPE;
> @@ -244,7 +244,7 @@ ptype_tunnel_with_udp(uint16_t *proto, const struct rte_mbuf *m,
> 			*proto = 0;
> 		}
> 		*off += gtp_len;
> -		hdr_lens->inner_l2_len = gtp_len + sizeof(struct rte_udp_hdr);
> +		hdr_lens->inner_l2_len = sizeof(struct rte_ether_hdr);
> 		hdr_lens->tunnel_len = gtp_len;
> 		if (port_no == RTE_GTPC_UDP_PORT)
> 			return RTE_PTYPE_TUNNEL_GTPC;
> @@ -262,7 +262,7 @@ ptype_tunnel_with_udp(uint16_t *proto, const struct rte_mbuf *m,
> 		geneve_len = sizeof(*gnh) + gnh->opt_len * 4;
> 		*off += geneve_len;
> 		hdr_lens->tunnel_len = geneve_len;
> -		hdr_lens->inner_l2_len = sizeof(struct rte_udp_hdr) + geneve_len;
> +		hdr_lens->inner_l2_len = sizeof(struct rte_ether_hdr);
> 		*proto = gnh->proto;
> 		if (gnh->proto == 0)
> 			*proto = rte_cpu_to_be_16(RTE_ETHER_TYPE_IPV4);
> @@ -498,7 +498,7 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf *m,
> 		pkt_type |= RTE_PTYPE_INNER_L2_ETHER;
> 		proto = eh->ether_type;
> 		off += sizeof(*eh);
> -		hdr_lens->inner_l2_len += sizeof(*eh);
> +		hdr_lens->inner_l2_len = sizeof(struct rte_ether_hdr);
> 	}
>
> 	if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN)) {
> @@ -511,7 +511,7 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf *m,
> 		if (unlikely(vh == NULL))
> 			return pkt_type;
> 		off += sizeof(*vh);
> -		hdr_lens->inner_l2_len += sizeof(*vh);
> +		hdr_lens->inner_l2_len += sizeof(struct rte_vlan_hdr);
> 		proto = vh->eth_proto;
> 	} else if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_QINQ)) {
> 		const struct rte_vlan_hdr *vh;
> @@ -524,7 +524,7 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf *m,
> 		if (unlikely(vh == NULL))
> 			return pkt_type;
> 		off += 2 * sizeof(*vh);
> -		hdr_lens->inner_l2_len += 2 * sizeof(*vh);
> +		hdr_lens->inner_l2_len += 2 * sizeof(struct rte_vlan_hdr);
> 		proto = vh->eth_proto;
> 	}
>
> -- 
> 2.47.3
>
>