[Bridge] [PATCH nf-next v2] netfilter:nft_meta: add NFT_META_VLAN support

[Nikolay Aleksandrov]

On 06/07/2019 17:29, wenxu wrote:
> 
> 在 2019/7/6 20:02, Nikolay Aleksandrov 写道:
>> On 05/07/2019 16:16, wenxu at ucloud.cn wrote:
>>> From: wenxu <wenxu at ucloud.cn>
>>>
>>> This patch provide a meta vlan to set the vlan tag of the packet.
>>>
>>> for q-in-q outer vlan id 20:
>>> meta vlan set 0x88a8:20
>>>
>>> set the default 0x8100 vlan type with vlan id 20
>>> meta vlan set 20
>>>
>>> Signed-off-by: wenxu <wenxu at ucloud.cn>
>>> ---
>>>  include/net/netfilter/nft_meta.h         |  5 ++++-
>>>  include/uapi/linux/netfilter/nf_tables.h |  4 ++++
>>>  net/netfilter/nft_meta.c                 | 25 +++++++++++++++++++++++++
>>>  3 files changed, 33 insertions(+), 1 deletion(-)
>>>
>> The patch looks fine, just a note: you'll only be able to work with the
>> outer tag, so guessing to achieve a double-tagged frame you'll have to
>> add another NFT_META_VLAN_INNER(?) and will have to organize them one
>> after another.
> 
> yes, It's just set/mangle the meta vlan data. 
> I think it's a good idear for stacked tagged with NFT_META_VLAN_INNER, in 
> this case it should check the the proto of vlan tag already on packet
> There are three case:
> 1. packet already contain a vlan header with proto 0x88a8, it should push the inner vlan tag
> 2. there is no outer vlan tag, maybe we should add a inner 0x8100 tag 
> and outer 0x88a8 tag?
> 3.  packet already contain a vlan tag with proto 0x8100, push the vlan tag and add outer 0x88a8 tag ?
> 

I'm more inclined to make it simpler, i.e. always push inner vlan. That way you can arrange them
anyway you like, also skb_vlan_push() already takes care of all that. It'll push the vlan
if hwaccel is present or make it hwaccel if it isn't.

In fact I'd suggest using skb_vlan_push(), so you don't need another NFT_META_VLAN_INNER,
this one can be re-used. If you chain 2 of these you'll get properly double-tagged frame.