netfilter: flowtable: fix nft_flow_route source address for nat case

For snat and dnat cases, the saddr should be taken from reverse tuple.

Fixes: 3412e164 (netfilter: flowtable: nft_flow_route use more data for reverse route)
Signed-off-by: Nwenxu <wenxu@chinatelecom.cn>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_flow_offload.c

@@ -232,7 +232,7 @@ static int nft_flow_route(const struct nft_pktinfo *pkt,
 	switch (nft_pf(pkt)) {
 	case NFPROTO_IPV4:
 		fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
-		fl.u.ip4.saddr = ct->tuplehash[dir].tuple.dst.u3.ip;
+		fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
 		fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
 		fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
 		fl.u.ip4.flowi4_tos = RT_TOS(ip_hdr(pkt->skb)->tos);
@@ -241,7 +241,7 @@ static int nft_flow_route(const struct nft_pktinfo *pkt,
 		break;
 	case NFPROTO_IPV6:
 		fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
-		fl.u.ip6.saddr = ct->tuplehash[dir].tuple.dst.u3.in6;
+		fl.u.ip6.saddr = ct->tuplehash[!dir].tuple.src.u3.in6;
 		fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
 		fl.u.ip6.flowi6_iif = this_dst->dev->ifindex;
 		fl.u.ip6.flowlabel = ip6_flowinfo(ipv6_hdr(pkt->skb));