On Fri, Nov 17, 2017 at 8:42 PM, David Miller <da...@davemloft.net> wrote:
> From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
> Date: Fri, 17 Nov 2017 17:59:13 -0500
>
>> Tuntap and similar devices can inject GSO packets. Accept type
>> VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.
>>
>> Processes are expected to use feature negotiation such as TUNSETOFFLOAD
>> to detect supported offload types and refrain from injecting other
>> packets. This process breaks down with live migration: guest kernels
>> do not renegotiate flags, so destination hosts need to expose all
>> features that the source host does.
>>
>> Partially revert the UFO removal from 182e0b6b5846~1..d9d30adf5677.
>> This patch introduces nearly(*) no new code to simplify verification.
>> It brings back verbatim tuntap UFO negotiation, VIRTIO_NET_HDR_GSO_UDP
>> insertion and software UFO segmentation.
>
> This looks good, one minor nit:
>
>> @@ -2369,6 +2369,10 @@ static int set_offload(struct tun_struct *tun,
>> unsigned long arg)
>> features |= NETIF_F_TSO6;
>> arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
>> }
>> +
>> + if (arg & TUN_F_UFO) {
>> + arg &= ~TUN_F_UFO;
>> + }
>
> This can be just simply "arg &= ~TUN_F_UFO;"? If anything the curly braces
> should be removed for a single statement basic block.
Okay, I'll fix that up in v2. At least for the initial version I wanted
to make as few changes as possible to the original code.
