From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Wed, 24 Mar 2021 02:30:38 +0100
Subject: [PATCH] netfilter: flowtable: add xmit path types

Add the xmit_type field that defines the two supported xmit paths in the
flowtable data plane, which are the neighbour and the xfrm xmit paths.
This patch prepares for new flowtable xmit path types to come.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -89,6 +89,11 @@ enum flow_offload_tuple_dir {
 };
 #define FLOW_OFFLOAD_DIR_MAX	IP_CT_DIR_MAX
 
+enum flow_offload_xmit_type {
+	FLOW_OFFLOAD_XMIT_NEIGH		= 0,
+	FLOW_OFFLOAD_XMIT_XFRM,
+};
+
 struct flow_offload_tuple {
 	union {
 		struct in_addr		src_v4;
@@ -111,7 +116,8 @@ struct flow_offload_tuple {
 	/* All members above are keys for lookups, see flow_offload_hash(). */
 	struct { }			__hash;
 
-	u8				dir;
+	u8				dir:6,
+					xmit_type:2;
 
 	u16				mtu;
 
@@ -157,7 +163,8 @@ static inline __s32 nf_flow_timeout_delt
 
 struct nf_flow_route {
 	struct {
-		struct dst_entry	*dst;
+		struct dst_entry		*dst;
+		enum flow_offload_xmit_type	xmit_type;
 	} tuple[FLOW_OFFLOAD_DIR_MAX];
 };
 
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -95,6 +95,7 @@ static int flow_offload_fill_route(struc
 	}
 
 	flow_tuple->iifidx = other_dst->dev->ifindex;
+	flow_tuple->xmit_type = route->tuple[dir].xmit_type;
 	flow_tuple->dst_cache = dst;
 
 	return 0;
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -235,8 +235,6 @@ nf_flow_offload_ip_hook(void *priv, stru
 
 	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;
@@ -265,13 +263,16 @@ nf_flow_offload_ip_hook(void *priv, stru
 	if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 		nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 
-	if (unlikely(dst_xfrm(&rt->dst))) {
+	rt = (struct rtable *)tuplehash->tuple.dst_cache;
+
+	if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 		memset(skb->cb, 0, sizeof(struct inet_skb_parm));
 		IPCB(skb)->iif = skb->dev->ifindex;
 		IPCB(skb)->flags = IPSKB_FORWARDED;
 		return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 	}
 
+	outdev = rt->dst.dev;
 	skb->dev = outdev;
 	nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr);
 	skb_dst_set_noref(skb, &rt->dst);
@@ -456,8 +457,6 @@ nf_flow_offload_ipv6_hook(void *priv, st
 
 	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;
@@ -485,13 +484,16 @@ nf_flow_offload_ipv6_hook(void *priv, st
 	if (flow_table->flags & NF_FLOWTABLE_COUNTER)
 		nf_ct_acct_update(flow->ct, tuplehash->tuple.dir, skb->len);
 
-	if (unlikely(dst_xfrm(&rt->dst))) {
+	rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
+
+	if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
 		memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 		IP6CB(skb)->iif = skb->dev->ifindex;
 		IP6CB(skb)->flags = IP6SKB_FORWARDED;
 		return nf_flow_xmit_xfrm(skb, state, &rt->dst);
 	}
 
+	outdev = rt->dst.dev;
 	skb->dev = outdev;
 	nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
 	skb_dst_set_noref(skb, &rt->dst);
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -19,6 +19,22 @@ struct nft_flow_offload {
 	struct nft_flowtable	*flowtable;
 };
 
+static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
+{
+	if (dst_xfrm(dst))
+		return FLOW_OFFLOAD_XMIT_XFRM;
+
+	return FLOW_OFFLOAD_XMIT_NEIGH;
+}
+
+static void nft_default_forward_path(struct nf_flow_route *route,
+				     struct dst_entry *dst_cache,
+				     enum ip_conntrack_dir dir)
+{
+	route->tuple[dir].dst		= dst_cache;
+	route->tuple[dir].xmit_type	= nft_xmit_type(dst_cache);
+}
+
 static int nft_flow_route(const struct nft_pktinfo *pkt,
 			  const struct nf_conn *ct,
 			  struct nf_flow_route *route,
@@ -44,8 +60,8 @@ static int nft_flow_route(const struct n
 	if (!other_dst)
 		return -ENOENT;
 
-	route->tuple[dir].dst		= this_dst;
-	route->tuple[!dir].dst		= other_dst;
+	nft_default_forward_path(route, this_dst, dir);
+	nft_default_forward_path(route, other_dst, !dir);
 
 	return 0;
 }