[PATCH 5.17 158/298] netfilter: nat: really support inet nat without l3 address

From: Greg Kroah-Hartman
Date: Mon Jun 13 2022 - 10:31:53 EST


From: Florian Westphal <fw@xxxxxxxxx>

[ Upstream commit 282e5f8fe907dc3f2fbf9f2103b0e62ffc3a68a5 ]

When no l3 address is given, priv->family is set to NFPROTO_INET and
the evaluation function isn't called.

Call it too so l4-only rewrite can work.
Also add a test case for this.

Fixes: a33f387ecd5aa ("netfilter: nft_nat: allow to specify layer 4 protocol NAT only")
Reported-by: Yi Chen <yiche@xxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/netfilter/nft_nat.c | 3 +-
tools/testing/selftests/netfilter/nft_nat.sh | 43 ++++++++++++++++++++
2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index be1595d6979d..db8f9116eeb4 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -334,7 +334,8 @@ static void nft_nat_inet_eval(const struct nft_expr *expr,
{
const struct nft_nat *priv = nft_expr_priv(expr);

- if (priv->family == nft_pf(pkt))
+ if (priv->family == nft_pf(pkt) ||
+ priv->family == NFPROTO_INET)
nft_nat_eval(expr, regs, pkt);
}

diff --git a/tools/testing/selftests/netfilter/nft_nat.sh b/tools/testing/selftests/netfilter/nft_nat.sh
index eb8543b9a5c4..924ecb3f1f73 100755
--- a/tools/testing/selftests/netfilter/nft_nat.sh
+++ b/tools/testing/selftests/netfilter/nft_nat.sh
@@ -374,6 +374,45 @@ EOF
return $lret
}

+test_local_dnat_portonly()
+{
+ local family=$1
+ local daddr=$2
+ local lret=0
+ local sr_s
+ local sr_r
+
+ip netns exec "$ns0" nft -f /dev/stdin <<EOF
+table $family nat {
+ chain output {
+ type nat hook output priority 0; policy accept;
+ meta l4proto tcp dnat to :2000
+
+ }
+}
+EOF
+ if [ $? -ne 0 ]; then
+ if [ $family = "inet" ];then
+ echo "SKIP: inet port test"
+ test_inet_nat=false
+ return
+ fi
+ echo "SKIP: Could not add $family dnat hook"
+ return
+ fi
+
+ echo SERVER-$family | ip netns exec "$ns1" timeout 5 socat -u STDIN TCP-LISTEN:2000 &
+ sc_s=$!
+
+ result=$(ip netns exec "$ns0" timeout 1 socat TCP:$daddr:2000 STDOUT)
+
+ if [ "$result" = "SERVER-inet" ];then
+ echo "PASS: inet port rewrite without l3 address"
+ else
+ echo "ERROR: inet port rewrite"
+ ret=1
+ fi
+}

test_masquerade6()
{
@@ -1148,6 +1187,10 @@ fi
reset_counters
test_local_dnat ip
test_local_dnat6 ip6
+
+reset_counters
+test_local_dnat_portonly inet 10.0.1.99
+
reset_counters
$test_inet_nat && test_local_dnat inet
$test_inet_nat && test_local_dnat6 inet
--
2.35.1