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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yi Chen <yiche@redhat.com>,
        Florian Westphal <fw@strlen.de>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 348/411] netfilter: nat: really support inet nat without l3 address
Date:   Mon, 13 Jun 2022 12:10:21 +0200
Message-Id: <20220613094939.142947044@linuxfoundation.org>
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From: Florian Westphal <fw@strlen.de>

[ 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@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 17c0f75dfcdb..0c5bc3c37ecf 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -283,7 +283,8 @@ 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 d7e07f4c3d7f..4e15e8167310 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()
 {
@@ -841,6 +880,10 @@ 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