Re: [PATCH v2] netfilter: nf_tables: add pkttype support to meta expression

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

On Fri, Jun 13, 2014 at 09:15:20AM +0200, Ana Rey wrote:
> Joint work with Álvaro Neira Ayuso <alvaroneay@gmail.com>
> 
> Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
> Signed-off-by: Ana Rey <anarey@gmail.com>
> ---
> [Changes in v2:]
> Put "case NFT_META_PKTTYPE:" outside of the #ifdef CONFIG_NETWORK_SECMARK.
> It was a mistake.
> Thanks to Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> for
> reporting this mistake.
> 
> 
>  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 2a88f64..9eb5153 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -571,6 +571,7 @@ enum nft_exthdr_attributes {
>   * @NFT_META_L4PROTO: layer 4 protocol number
>   * @NFT_META_BRI_IIFNAME: packet input bridge interface name
>   * @NFT_META_BRI_OIFNAME: packet output bridge interface name
> + * @NFT_META_PKTTYPE: Packet class
                                ^^^^^
type?

>   */
>  enum nft_meta_keys {
>  	NFT_META_LEN,
> @@ -592,6 +593,7 @@ enum nft_meta_keys {
>  	NFT_META_L4PROTO,
>  	NFT_META_BRI_IIFNAME,
>  	NFT_META_BRI_OIFNAME,
> +	NFT_META_PKTTYPE,
>  };
>  
>  /**
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index 852b178..eb9882e 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -14,6 +14,9 @@
>  #include <linux/netlink.h>
>  #include <linux/netfilter.h>
>  #include <linux/netfilter/nf_tables.h>
> +#include <linux/in.h>
> +#include <linux/ip.h>
> +#include <linux/ipv6.h>
>  #include <net/dst.h>
>  #include <net/sock.h>
>  #include <net/tcp_states.h> /* for TCP_TIME_WAIT */
> @@ -124,6 +127,19 @@ void nft_meta_get_eval(const struct nft_expr *expr,
>  		dest->data[0] = skb->secmark;
>  		break;
>  #endif
> +	case NFT_META_PKTTYPE:
> +		dest->data[0] = skb->pkt_type;
> +		if (skb->pkt_type != PACKET_LOOPBACK)
> +			dest->data[0] = skb->pkt_type;
> +		else if (expr->ops->type->family == NFPROTO_IPV4 &&
                         ^----------------------^

This has problems with NFPROTO_INET, NFPROTO_BRIDGE and NFPROTO_ARP
when handling the loopback case.

You have to add a nft_meta per family, something similar to:

05513e9 netfilter: nf_tables: add reject module for NFPROTO_INET

In NFPROTO_INET, you have to use:

        if (pkt->ops->pf == NF_PROTO_IPV4)
                ...

In NFPROTO_BRIDGE, you have to use:

        if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)
                ...

In NFPROTO_ARP, you have to check the destination address:

        if (is_broadcast_ether_addr(ethhdr->h_dest)
                ...

> +			 ipv4_is_multicast(ip_hdr(skb)->daddr))
> +			dest->data[0] = PACKET_MULTICAST;
> +		else if (expr->ops->type->family == NFPROTO_IPV6 &&
> +			 ipv6_hdr(skb)->daddr.s6_addr[0] == 0xFF)
> +			dest->data[0] = PACKET_MULTICAST;
> +		else
> +			dest->data[0] = PACKET_BROADCAST;
> +		break;
>  	default:
>  		WARN_ON(1);
>  		goto err;
> @@ -195,6 +211,7 @@ int nft_meta_get_init(const struct nft_ctx *ctx,
>  #ifdef CONFIG_NETWORK_SECMARK
>  	case NFT_META_SECMARK:
>  #endif
> +	case NFT_META_PKTTYPE:
>  		break;
>  	default:
>  		return -EOPNOTSUPP;
> -- 
> 2.0.0
> 
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