netdev - Re: [PATCH net] net: drop bad gso csum_start and offset in virtio_net

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Message-ID: <aad76753-d2b5-4905-b90b-e31483e5956b@redhat.com>
Date: Fri, 26 Jul 2024 16:48:06 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
 edumazet@...gle.com, mst@...hat.com, jasowang@...hat.com, arefev@...mel.ru,
 alexander.duyck@...il.com, Willem de Bruijn <willemb@...gle.com>,
 stable@...r.kernel.org
Subject: Re: [PATCH net] net: drop bad gso csum_start and offset in
 virtio_net_hdr

On 7/26/24 15:52, Willem de Bruijn wrote:
> On Fri, Jul 26, 2024 at 4:23 AM Paolo Abeni <pabeni@...hat.com> wrote:
>>
>> On 7/26/24 04:32, Willem de Bruijn wrot> @@ -182,6 +171,11 @@ static
>> inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
>>>                        if (gso_type != SKB_GSO_UDP_L4)
>>>                                return -EINVAL;
>>>                        break;
>>> +             case SKB_GSO_TCPV4:
>>> +             case SKB_GSO_TCPV6:
>>
>> I think we need to add here an additional check:
>>
>>                          if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
>>                                  return -EINVAL;
>>
> 
> Historically this interface has been able to request
> VIRTIO_NET_HDR_GSO_* without VIRTIO_NET_HDR_F_NEEDS_CSUM.

I see. I looked at the SKB_GSO_UDP_L4 case, but I did not dig into history.

> I would love to clamp down on this, as those packets are essentially
> illegal. But we should probably leave that discussion for a separate
> patch?

Yep, I guess we have to keep the two discussion separate.

As a consequence, I'm fine with the current checks (with Eric's 
suggested changes).

Thanks,

Paolo