Re: [PATCH net] gve: ignore nonrelevant GSO type bits when processing TSO headers

[Andrei Vagin]

On Thu, Jun 6, 2024 at 12:22 PM <joshwash@xxxxxxxxxx> wrote:
>
> From: Joshua Washington <joshwash@xxxxxxxxxx>
>
> TSO currently fails when the skb's gso_type field has more than one bit
> set.
>
> TSO packets can be passed from userspace using PF_PACKET, TUNTAP and a
> few others, using virtio_net_hdr (e.g., PACKET_VNET_HDR). This includes
> virtualization, such as QEMU, a real use-case.

Here is the bug report where this issue was triggered by gVisor:
https://github.com/google/gvisor/issues/10344

>
> The gso_type and gso_size fields as passed from userspace in
> virtio_net_hdr are not trusted blindly by the kernel. It adds gso_type
> |= SKB_GSO_DODGY to force the packet to enter the software GSO stack
> for verification.
>
> This issue might similarly come up when the CWR bit is set in the TCP
> header for congestion control, causing the SKB_GSO_TCP_ECN gso_type bit
> to be set.
>
> Fixes: a57e5de476be ("gve: DQO: Add TX path")
>
> Signed-off-by: Joshua Washington <joshwash@xxxxxxxxxx>
> Reviewed-by: Praveen Kaligineedi <pkaligineedi@xxxxxxxxxx>
> Reviewed-by: Harshitha Ramamurthy <hramamurthy@xxxxxxxxxx>
> Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>

Acked-by: Andrei Vagin <avagin@xxxxxxxxx>

Thanks,
Andrei