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

[Pablo Neira Ayuso]

On Sat, Jun 15, 2019 at 08:14:21PM +0800, we...@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.

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

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