netdev - Re: [PATCH v7 net-next 01/16] gso: Remove arbitrary checks for unsupported GSO

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Date:	Sun, 22 May 2016 14:33:53 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Tom Herbert <tom@...bertland.com>, davem@...emloft.net,
	netdev@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH v7 net-next 01/16] gso: Remove arbitrary checks for
 unsupported GSO

On 22.05.2016 09:44, Michael S. Tsirkin wrote:
> On Sat, May 21, 2016 at 03:02:30AM +0200, Hannes Frederic Sowa wrote:
>> Hello,
>>
>> On 18.05.2016 18:06, Tom Herbert wrote:
>>> In several gso_segment functions there are checks of gso_type against
>>> a seemingly arbitrary list of SKB_GSO_* flags. This seems like an
>>> attempt to identify unsupported GSO types, but since the stack is
>>> the one that set these GSO types in the first place this seems
>>> unnecessary to do. If a combination isn't valid in the first
>>> place that stack should not allow setting it.
>>>
>>> This is a code simplication especially for add new GSO types.
>>
>> I couldn't still wrap my head around this.
>>
>> I wonder if this is safe in case of if the packet is generated from an
>> untrusted virtual machine over virtio_net?
>>
>> Bye,
>> Hannes
> 
> I'm not sure how you use virtio_net, but neither it nor tun or macvtap
> commonly used as backends for it pass gso flags through
> from untrusted entities.

Sorry for the noise, I see the flags gets sanitized during transport.

Thanks,
Hannes