[PATCH AUTOSEL 4.20 043/105] netfilter: nft_flow_offload: Fix reverse route lookup

Sasha Levin
2019-02-13T03:02:48Z

From: wenxu <wenxu@ucloud.cn>

[ Upstream commit a799aea0988ea0d1b1f263e996fdad2f6133c680 ]

Using the following example:

client 1.1.1.7 ---> 2.2.2.7 which dnat to 10.0.0.7 server

The first reply packet (ie. syn+ack) uses an incorrect destination
address for the reverse route lookup since it uses:

daddr = ct->tuplehash[!dir].tuple.dst.u3.ip;

which is 2.2.2.7 in the scenario that is described above, while this
should be:

daddr = ct->tuplehash[dir].tuple.src.u3.ip;

that is 10.0.0.7.

Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nft_flow_offload.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 974525eb92df..ccdb8f5ababb 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -29,10 +29,10 @@ static int nft_flow_route(const struct nft_pktinfo *pkt,
memset(&fl, 0, sizeof(fl));
switch (nft_pf(pkt)) {
case NFPROTO_IPV4:
- fl.u.ip4.daddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
+ fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
break;
case NFPROTO_IPV6:
- fl.u.ip6.daddr = ct->tuplehash[!dir].tuple.dst.u3.in6;
+ fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
break;
}

--
2.19.1