Re: [PATCH 1/2 nf-next] netfilter: nft_meta: add NFT_META_BRI_PVID support

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, Jun 19, 2019 at 03:16:24PM +0800, wenxu@ucloud.cn wrote:
> From: wenxu <wenxu@ucloud.cn>
> 
> nft add table bridge firewall
> nft add chain bridge firewall zones { type filter hook prerouting priority - 300 \; }
> nft add rule bridge firewall zones counter ct zone set vlan id map { 100 : 1, 200 : 2 }

> As above set the bridge port with pvid, the received packet don't contain
> the vlan tag which means the packet should belong to vlan 200 through pvid.
> With this pacth user can get the pvid of bridge ports: "meta brpvid"

Would you also post the patches for nftables for review?

Would you post an example on how you use "meta brpvid" in your
ruleset? I don't see this is used in the example above,

More comments below.

> Signed-off-by: wenxu <wenxu@ucloud.cn>
> ---
>  include/uapi/linux/netfilter/nf_tables.h |  2 ++
>  net/netfilter/nft_meta.c                 | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 31a6b8f..4a16124 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -793,6 +793,7 @@ enum nft_exthdr_attributes {
>   * @NFT_META_SECPATH: boolean, secpath_exists (!!skb->sp)
>   * @NFT_META_IIFKIND: packet input interface kind name (dev->rtnl_link_ops->kind)
>   * @NFT_META_OIFKIND: packet output interface kind name (dev->rtnl_link_ops->kind)
> + * @NFT_META_BRI_PVID: packet input bridge port pvid
>   */
>  enum nft_meta_keys {
>  	NFT_META_LEN,
> @@ -823,6 +824,7 @@ enum nft_meta_keys {
>  	NFT_META_SECPATH,
>  	NFT_META_IIFKIND,
>  	NFT_META_OIFKIND,
> +	NFT_META_BRI_PVID,
>  };
>  
>  /**
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index 987d2d6..1fdb565 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -243,6 +243,18 @@ void nft_meta_get_eval(const struct nft_expr *expr,
>  			goto err;
>  		strncpy((char *)dest, p->br->dev->name, IFNAMSIZ);
>  		return;
> +	case NFT_META_BRI_PVID:
> +		if (in == NULL || (p = br_port_get_rtnl_rcu(in)) == NULL)
> +			goto err;
> +		if (br_opt_get(p->br, BROPT_VLAN_ENABLED)) {
> +			u16 pvid = br_get_pvid(nbp_vlan_group_rcu(p));
> +
> +			if (pvid) {
> +				nft_reg_store16(dest, pvid);

I think you should store pvid into dest if pvid is zero too, right?
You cannot assume destination register is set to zero.

> +				return;
> +			}
> +		}
> +		goto err;
>  #endif
>  	case NFT_META_IIFKIND:
>  		if (in == NULL || in->rtnl_link_ops == NULL)
> @@ -370,6 +382,11 @@ static int nft_meta_get_init(const struct nft_ctx *ctx,
>  			return -EOPNOTSUPP;
>  		len = IFNAMSIZ;
>  		break;
> +	case NFT_META_BRI_PVID:
> +		if (ctx->family != NFPROTO_BRIDGE)
> +			return -EOPNOTSUPP;
> +		len = sizeof(u16);
> +		break;
>  #endif
>  	default:
>  		return -EOPNOTSUPP;
> -- 
> 1.8.3.1
>