netdev - Re: [PATCH net] af_packet: fix raw sockets over 6in4 tunnel

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Date:   Tue, 15 Jan 2019 10:49:49 +0100
From:   Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH net] af_packet: fix raw sockets over 6in4 tunnel

Le 14/01/2019 à 16:38, Willem de Bruijn a écrit :
> On Mon, Jan 14, 2019 at 10:15 AM Willem de Bruijn
> <willemdebruijn.kernel@...il.com> wrote:
[snip]
>> It is wrong because for other devices l2 header length is not zero, so
>> this incorrectly sets skb->network_header to the start of the link
>> layer header on all those devices.
Ok, thank you for the details.

>>
>> A one line variant of the above would be
>>
>> -               if (len < reserve)
>> +               if (len < reserve + sizeof(struct ipv6hdr))
> 
> and exclude the majority of devices with fixed hard header len. Those
> require len to be >= reserve, so this workaround does not apply to
> them:
> 
> if (len < reserve + sizeof(struct ipv6hdr) &&
>     dev->min_header_len != dev->hard_header_len)
> 
And what about:
- if (len < reserve)
+ if (dev->min_header_len != dev->hard_header_len)
 	skb_reset_network_header(skb);
?