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

Nikolay Aleksandrov nikolay at cumulusnetworks.com
Sun Jul 7 10:13:47 UTC 2019

On 07/07/2019 13:12, Nikolay Aleksandrov wrote:
> 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.

You just need to be careful because skb_vlan_push expects skb->data to be at the mac header.

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