Re: [PATCH nf-next 5/7] netfilter: flowtable: store ethertype in flowtable context

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> Add a new field to store the ethertype of the packet, skipping layer 2
> encapsulation. Store the ether_type in the context after parsing the
> layer 2 header for the first time and then use it later on.
> 
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>

> ---
>  net/netfilter/nf_flow_table_ip.c | 47 +++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 19 deletions(-)
> 
> diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> index ed90809b206e..4437f3a13cb2 100644
> --- a/net/netfilter/nf_flow_table_ip.c
> +++ b/net/netfilter/nf_flow_table_ip.c
> @@ -147,6 +147,7 @@ static bool ip_has_options(unsigned int thoff)
>  
>  struct nf_flowtable_ctx {
>  	const struct net_device	*in;
> +	__be16			ether_type;
>  	u32			offset;
>  	u32			hdrsize;
>  	struct {
> @@ -161,7 +162,6 @@ static void nf_flow_tuple_encap(struct nf_flowtable_ctx *ctx,
>  				struct sk_buff *skb,
>  				struct flow_offload_tuple *tuple)
>  {
> -	__be16 inner_proto = skb->protocol;
>  	struct vlan_ethhdr *veth;
>  	struct pppoe_hdr *phdr;
>  	struct ipv6hdr *ip6h;
> @@ -179,19 +179,17 @@ static void nf_flow_tuple_encap(struct nf_flowtable_ctx *ctx,
>  		veth = (struct vlan_ethhdr *)skb_mac_header(skb);
>  		tuple->encap[i].id = ntohs(veth->h_vlan_TCI);
>  		tuple->encap[i].proto = skb->protocol;
> -		inner_proto = veth->h_vlan_encapsulated_proto;
>  		offset += VLAN_HLEN;
>  		break;
>  	case htons(ETH_P_PPP_SES):
>  		phdr = (struct pppoe_hdr *)skb_network_header(skb);
>  		tuple->encap[i].id = ntohs(phdr->sid);
>  		tuple->encap[i].proto = skb->protocol;
> -		inner_proto = *((__be16 *)(phdr + 1));
>  		offset += PPPOE_SES_HLEN;
>  		break;
>  	}
>  
> -	switch (inner_proto) {
> +	switch (ctx->ether_type) {
>  	case htons(ETH_P_IP):
>  		iph = (struct iphdr *)(skb_network_header(skb) + offset);
>  		if (ctx->tun.inner_proto == IPPROTO_IPIP) {
> @@ -376,10 +374,10 @@ static void nf_flow_ip_tunnel_pop(struct nf_flowtable_ctx *ctx,
>  }
>  
>  static bool nf_flow_skb_encap_protocol(struct nf_flowtable_ctx *ctx,
> -				       struct sk_buff *skb, __be16 proto)
> +				       struct sk_buff *skb)
>  {
> -	__be16 inner_proto = skb->protocol;
>  	struct vlan_ethhdr *veth;
> +	__be16 ether_type;
>  	bool ret = false;
>  
>  	switch (skb->protocol) {
> @@ -388,22 +386,27 @@ static bool nf_flow_skb_encap_protocol(struct nf_flowtable_ctx *ctx,
>  			return false;
>  
>  		veth = (struct vlan_ethhdr *)skb_mac_header(skb);
> -		if (veth->h_vlan_encapsulated_proto == proto) {
> -			ctx->offset += VLAN_HLEN;
> -			inner_proto = proto;
> -			ret = true;
> -		}
> +		ctx->ether_type = veth->h_vlan_encapsulated_proto;
> +		ctx->offset += VLAN_HLEN;
> +		ret = true;
>  		break;
>  	case htons(ETH_P_PPP_SES):
> -		if (nf_flow_pppoe_proto(skb, &inner_proto) &&
> -		    inner_proto == proto) {
> -			ctx->offset += PPPOE_SES_HLEN;
> -			ret = true;
> -		}
> +		if (!nf_flow_pppoe_proto(skb, &ether_type))
> +			return false;
> +
> +		ctx->ether_type = ether_type;
> +		ctx->offset += PPPOE_SES_HLEN;
> +		ret = true;
> +		break;
> +	case htons(ETH_P_IP):
> +	case htons(ETH_P_IPV6):
> +		ctx->ether_type = skb->protocol;
>  		break;
> +	default:
> +		return false;
>  	}
>  
> -	switch (inner_proto) {
> +	switch (ctx->ether_type) {
>  	case htons(ETH_P_IP):
>  		ret = nf_flow_ip4_tunnel_proto(ctx, skb);
>  		break;
> @@ -455,7 +458,10 @@ nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx,
>  {
>  	struct flow_offload_tuple tuple = {};
>  
> -	if (!nf_flow_skb_encap_protocol(ctx, skb, htons(ETH_P_IP)))
> +	if (!nf_flow_skb_encap_protocol(ctx, skb))
> +		return NULL;
> +
> +	if (unlikely(ctx->ether_type != htons(ETH_P_IP)))
>  		return NULL;
>  
>  	if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0)
> @@ -1101,7 +1107,10 @@ nf_flow_offload_ipv6_lookup(struct nf_flowtable_ctx *ctx,
>  {
>  	struct flow_offload_tuple tuple = {};
>  
> -	if (!nf_flow_skb_encap_protocol(ctx, skb, htons(ETH_P_IPV6)))
> +	if (!nf_flow_skb_encap_protocol(ctx, skb))
> +		return NULL;
> +
> +	if (unlikely(ctx->ether_type != htons(ETH_P_IPV6)))
>  		return NULL;
>  
>  	if (nf_flow_tuple_ipv6(ctx, skb, &tuple) < 0)
> -- 
> 2.47.3
> 

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