Subject: Re: [PATCH net] macvtap: fix network header pointer for VLAN tagged pkts

From: Ivan Vecera <[email-masked]>
Date: Tue, 21 Jul 2015 09:11:38 +0200

On 07/20/2015 06:42 PM, Vlad Yasevich wrote:
> On 07/20/2015 11:44 AM, Ivan Vecera wrote:
>> Network header is set with offset ETH_HLEN but it is not true for VLAN
>> (multiple-)tagged and results in checksum issues in lower devices.
>>
>> Signed-off-by: Ivan Vecera <[email-masked]>
>> ---
>>   drivers/net/macvtap.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
>> index 3b933bb..cdcbab4 100644
>> --- a/drivers/net/macvtap.c
>> +++ b/drivers/net/macvtap.c
>> @@ -796,6 +796,12 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
>>   	skb_reset_mac_header(skb);
>>   	skb->protocol = eth_hdr(skb)->h_proto;
>>
>> +	if (skb_vlan_tagged(skb)) {
>> +		int depth;
>> +		skb->protocol = __vlan_get_protocol(skb, skb->protocol, &depth);
>
> I don't think this is right.  This would reset the protocol to the encapsulated
> protocol which isn't really the case since you are not really stripping vlan
> encapsulations.
>
> -vlad
Yup, you are right, skb->protocol should be untouched. Will post v2.

Ivan