netdev - Re: [PATCH net-next,v2 6/9] netfilter: flowtable: use dev_fill_forward

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Date:   Mon, 19 Oct 2020 10:32:08 +0100
From:   Jeremy Sowden <jeremy@...zel.net>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     netfilter-devel@...r.kernel.org, davem@...emloft.net,
        netdev@...r.kernel.org, kuba@...nel.org
Subject: Re: [PATCH net-next,v2 6/9] netfilter: flowtable: use
 dev_fill_forward_path() to obtain egress device

On 2020-10-15, at 18:30:35 +0200, Pablo Neira Ayuso wrote:
> The egress device in the tuple is obtained from route. Use
> dev_fill_forward_path() instead to provide the real ingress device for
                                                      ^^^^^^^

Should this be "egress"?

> this flow whenever this is available.
>
> Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
> ---
> v2: no changes.
>
>  include/net/netfilter/nf_flow_table.h |  4 ++++
>  net/netfilter/nf_flow_table_core.c    |  1 +
>  net/netfilter/nf_flow_table_ip.c      | 25 +++++++++++++++++++++++--
>  net/netfilter/nft_flow_offload.c      |  1 +
>  4 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
> index ecb84d4358cc..fe225e881cc7 100644
> --- a/include/net/netfilter/nf_flow_table.h
> +++ b/include/net/netfilter/nf_flow_table.h
> @@ -117,6 +117,7 @@ struct flow_offload_tuple {
>  	u8				dir;
>  	enum flow_offload_xmit_type	xmit_type:8;
>  	u16				mtu;
> +	u32				oifidx;
>
>  	struct dst_entry		*dst_cache;
>  };
> @@ -164,6 +165,9 @@ struct nf_flow_route {
>  		struct {
>  			u32		ifindex;
>  		} in;
> +		struct {
> +			u32		ifindex;
> +		} out;
>  		struct dst_entry	*dst;
>  	} tuple[FLOW_OFFLOAD_DIR_MAX];
>  };
> diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
> index 66abc7f287a3..99f01f08c550 100644
> --- a/net/netfilter/nf_flow_table_core.c
> +++ b/net/netfilter/nf_flow_table_core.c
> @@ -94,6 +94,7 @@ static int flow_offload_fill_route(struct flow_offload *flow,
>  	}
>
>  	flow_tuple->iifidx = route->tuple[dir].in.ifindex;
> +	flow_tuple->oifidx = route->tuple[dir].out.ifindex;
>
>  	if (dst_xfrm(dst))
>  		flow_tuple->xmit_type = FLOW_OFFLOAD_XMIT_XFRM;
> diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> index e215c79e6777..92f444db8d9f 100644
> --- a/net/netfilter/nf_flow_table_ip.c
> +++ b/net/netfilter/nf_flow_table_ip.c
> @@ -228,6 +228,15 @@ static int nf_flow_offload_dst_check(struct dst_entry *dst)
>  	return 0;
>  }
>
> +static struct net_device *nf_flow_outdev_lookup(struct net *net, int oifidx,
> +						struct net_device *dev)
> +{
> +	if (oifidx == dev->ifindex)
> +		return dev;
> +
> +	return dev_get_by_index_rcu(net, oifidx);
> +}
> +
>  static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb,
>  				      const struct nf_hook_state *state,
>  				      struct dst_entry *dst)
> @@ -267,7 +276,6 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
>  	dir = tuplehash->tuple.dir;
>  	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
>  	rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
> -	outdev = rt->dst.dev;
>
>  	if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
>  		return NF_ACCEPT;
> @@ -286,6 +294,13 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
>  		return NF_ACCEPT;
>  	}
>
> +	outdev = nf_flow_outdev_lookup(state->net, tuplehash->tuple.oifidx,
> +				       rt->dst.dev);
> +	if (!outdev) {
> +		flow_offload_teardown(flow);
> +		return NF_ACCEPT;
> +	}
> +
>  	if (nf_flow_nat_ip(flow, skb, thoff, dir) < 0)
>  		return NF_DROP;
>
> @@ -517,7 +532,6 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
>  	dir = tuplehash->tuple.dir;
>  	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
>  	rt = (struct rt6_info *)flow->tuplehash[dir].tuple.dst_cache;
> -	outdev = rt->dst.dev;
>
>  	if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
>  		return NF_ACCEPT;
> @@ -533,6 +547,13 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
>  		return NF_ACCEPT;
>  	}
>
> +	outdev = nf_flow_outdev_lookup(state->net, tuplehash->tuple.oifidx,
> +				       rt->dst.dev);
> +	if (!outdev) {
> +		flow_offload_teardown(flow);
> +		return NF_ACCEPT;
> +	}
> +
>  	if (skb_try_make_writable(skb, sizeof(*ip6h)))
>  		return NF_DROP;
>
> diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
> index 4b476b0a3c88..6a6633e2ceeb 100644
> --- a/net/netfilter/nft_flow_offload.c
> +++ b/net/netfilter/nft_flow_offload.c
> @@ -84,6 +84,7 @@ static int nft_dev_forward_path(struct nf_flow_route *route,
>  	}
>
>  	route->tuple[!dir].in.ifindex = info.iifindex;
> +	route->tuple[dir].out.ifindex = info.iifindex;
>
>  	return 0;
>  }
> --
> 2.20.1

J.

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