Re: [PATCH net-next] netfilter: bridge: add nft_bridge_pvid to tag the default pvid for non-tagged packet

[wenxu <wenxu@ucloud.cn>]

On 6/19/2019 12:40 AM, Pablo Neira Ayuso wrote:
> On Sat, Jun 15, 2019 at 08:14:21PM +0800, wenxu@ucloud.cn wrote:
> [...]
>> +static void nft_bridge_pvid_eval(const struct nft_expr *expr,
>> +				 struct nft_regs *regs,
>> +				 const struct nft_pktinfo *pkt)
>> +{
>> +	struct sk_buff *skb = pkt->skb;
>> +	struct net_bridge_port *p;
>> +
>> +	p = br_port_get_rtnl_rcu(skb->dev);
>> +
>> +	if (p && br_opt_get(p->br, BROPT_VLAN_ENABLED) &&
>> +	    !skb_vlan_tag_present(skb)) {
>> +		u16 pvid = br_get_pvid(nbp_vlan_group_rcu(p));
>> +
>> +		if (pvid)
>> +			__vlan_hwaccel_put_tag(skb, p->br->vlan_proto, pvid);
> I see two things here:
>
> #1 Extend new NFT_META_BRIDGE_PVID nft_meta to fetch of 'pvid',
>    probably add net/bridge/netfilter/nft_meta_bridge.c for this.
I can get this, it provide a bridge pvid (get meta). But why put it in

nft_meta_bridge.c but not nft_meta.c?

>
> #2 Extend nft_meta to allow to set the vlan tag via
>    __vlan_hwaccel_put_tag().

why there is also extend nft_meta?  So it's a set meta. Is "vlan id set"

 not base on nft_payload ?

>
> If these two changes are in place, then it should be possible to set
> skbuff vlan id based on the pvid, if this is what you need.
>
> This would allow for:
>
>         vlan id set bridge pvid
>