Re: [PATCH net v2] gve: ignore nonrelevant GSO type bits when processing TSO headers

[Willem de Bruijn]

joshwash@ 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.
> 
> 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>
> Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
> Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Acked-by: Andrei Vagin <avagin@xxxxxxxxx>

I did not mean to ask for a revision. When you send a v2, please do include
a changelog

> ---
>  drivers/net/ethernet/google/gve/gve_tx_dqo.c | 21 +++++---------------
>  1 file changed, 5 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
> index fe1b26a4d736..a76b407a981b 100644
> --- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
> +++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
> @@ -551,32 +551,21 @@ static int gve_prep_tso(struct sk_buff *skb)
>  	 * - Hypervisor enforces a limit of 9K MTU
>  	 * - Kernel will not produce a TSO larger than 64k
>  	 */
> -

Accidental removal?

>  	if (unlikely(skb_shinfo(skb)->gso_size < GVE_TX_MIN_TSO_MSS_DQO))
>  		return -1;
>  
> +	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
> +		return -EINVAL;
> +