netdev - Re: [PATCH 2/2 nf-next] netfilter:nft_meta: add NFT_META

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Date:   Thu, 27 Jun 2019 14:35:50 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     wenxu@...oud.cnf
Cc:     fw@...len.de, netfilter-devel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 2/2 nf-next] netfilter:nft_meta: add NFT_META_VLAN support

On Thu, Jun 27, 2019 at 10:09:17AM +0800, wenxu@...oud.cn wrote:
> From: wenxu <wenxu@...oud.cn>
> 
> This patch provide a meta vlan to set the vlan tag of the packet.
> 
> for q-in-q vlan id 20:
> meta vlan set 0x88a8:20

Actually, I think this is not very useful for stacked vlan since this
just sets/mangles the existing meta vlan data.

We'll need infrastructure that uses skb_vlan_push() and _pop().

Patch looks good anyway, such infrastructure to push/pop can be added
later on.

Thanks.

> set the default 0x8100 vlan type with vlan id 20
> meta vlan set 20
> 
> Signed-off-by: wenxu <wenxu@...oud.cn>
> ---
>  include/uapi/linux/netfilter/nf_tables.h |  4 ++++
>  net/netfilter/nft_meta.c                 | 27 ++++++++++++++++++++++++++-
>  2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 0b18646..cf037f2 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -797,6 +797,7 @@ enum nft_exthdr_attributes {
>   * @NFT_META_OIFKIND: packet output interface kind name (dev->rtnl_link_ops->kind)
>   * @NFT_META_BRI_PVID: packet input bridge port pvid
>   * @NFT_META_BRI_VLAN_PROTO: packet input bridge vlan proto
> + * @NFT_META_VLAN: packet vlan metadata
>   */
>  enum nft_meta_keys {
>  	NFT_META_LEN,
> @@ -829,6 +830,7 @@ enum nft_meta_keys {
>  	NFT_META_OIFKIND,
>  	NFT_META_BRI_PVID,
>  	NFT_META_BRI_VLAN_PROTO,
> +	NFT_META_VLAN,
>  };
>  
>  /**
> @@ -895,12 +897,14 @@ enum nft_hash_attributes {
>   * @NFTA_META_DREG: destination register (NLA_U32)
>   * @NFTA_META_KEY: meta data item to load (NLA_U32: nft_meta_keys)
>   * @NFTA_META_SREG: source register (NLA_U32)
> + * @NFTA_META_SREG2: source register (NLA_U32)
>   */
>  enum nft_meta_attributes {
>  	NFTA_META_UNSPEC,
>  	NFTA_META_DREG,
>  	NFTA_META_KEY,
>  	NFTA_META_SREG,
> +	NFTA_META_SREG2,
>  	__NFTA_META_MAX
>  };
>  #define NFTA_META_MAX		(__NFTA_META_MAX - 1)
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index e3adf6a..29a6679 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -28,7 +28,10 @@ struct nft_meta {
>  	enum nft_meta_keys	key:8;
>  	union {
>  		enum nft_registers	dreg:8;
> -		enum nft_registers	sreg:8;
> +		struct {
> +			enum nft_registers	sreg:8;
> +			enum nft_registers	sreg2:8;
> +		};
>  	};
>  };
>  
> @@ -312,6 +315,17 @@ static void nft_meta_set_eval(const struct nft_expr *expr,
>  		skb->secmark = value;
>  		break;
>  #endif
> +	case NFT_META_VLAN: {
> +		u32 *sreg2 = &regs->data[meta->sreg2];
> +		__be16 vlan_proto;
> +		u16 vlan_tci;
> +
> +		vlan_tci = nft_reg_load16(sreg);
> +		vlan_proto = nft_reg_load16(sreg2);
> +
> +		__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
> +		break;
> +	}
>  	default:
>  		WARN_ON(1);
>  	}
> @@ -321,6 +335,7 @@ static void nft_meta_set_eval(const struct nft_expr *expr,
>  	[NFTA_META_DREG]	= { .type = NLA_U32 },
>  	[NFTA_META_KEY]		= { .type = NLA_U32 },
>  	[NFTA_META_SREG]	= { .type = NLA_U32 },
> +	[NFTA_META_SREG2]	= { .type = NLA_U32 },
>  };
>  
>  static int nft_meta_get_init(const struct nft_ctx *ctx,
> @@ -483,6 +498,13 @@ static int nft_meta_set_init(const struct nft_ctx *ctx,
>  	case NFT_META_PKTTYPE:
>  		len = sizeof(u8);
>  		break;
> +	case NFT_META_VLAN:
> +		len = sizeof(u16);
> +		priv->sreg2 = nft_parse_register(tb[NFTA_META_SREG2]);
> +		err = nft_validate_register_load(priv->sreg2, len);
> +		if (err < 0)
> +			return err;
> +		break;
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> @@ -521,6 +543,9 @@ static int nft_meta_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
>  		goto nla_put_failure;
>  	if (nft_dump_register(skb, NFTA_META_SREG, priv->sreg))
>  		goto nla_put_failure;
> +	if (priv->key == NFT_META_VLAN &&
> +	    nft_dump_register(skb, NFTA_META_SREG2, priv->sreg2))
> +		goto nla_put_failure;
>  
>  	return 0;
>  
> -- 
> 1.8.3.1
>