selftests: vrf: Add test for SNAT over VRF

Commit 09e856d5 ("vrf: Reset skb conntrack connection on VRF rcv")
fixes the "reverse-DNAT" of an SNAT-ed packet over a VRF.

This patch adds a test for this scenario.
Signed-off-by: Lahav Schlesinger <lschlesinger@drivenets.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/fcnal-test.sh

@@ -3879,6 +3879,32 @@ use_case_ping_lla_multi()
 	log_test_addr ${MCAST}%${NSC_DEV} $? 0 "Post cycle ${NSA} ${NSA_DEV2}, ping out ns-C"
 }
 
+# Perform IPv{4,6} SNAT on ns-A, and verify TCP connection is successfully
+# established with ns-B.
+use_case_snat_on_vrf()
+{
+	setup "yes"
+
+	local port="12345"
+
+	run_cmd iptables -t nat -A POSTROUTING -p tcp -m tcp --dport ${port} -j SNAT --to-source ${NSA_LO_IP} -o ${VRF}
+	run_cmd ip6tables -t nat -A POSTROUTING -p tcp -m tcp --dport ${port} -j SNAT --to-source ${NSA_LO_IP6} -o ${VRF}
+
+	run_cmd_nsb nettest -s -l ${NSB_IP} -p ${port} &
+	sleep 1
+	run_cmd nettest -d ${VRF} -r ${NSB_IP} -p ${port}
+	log_test $? 0 "IPv4 TCP connection over VRF with SNAT"
+
+	run_cmd_nsb nettest -6 -s -l ${NSB_IP6} -p ${port} &
+	sleep 1
+	run_cmd nettest -6 -d ${VRF} -r ${NSB_IP6} -p ${port}
+	log_test $? 0 "IPv6 TCP connection over VRF with SNAT"
+
+	# Cleanup
+	run_cmd iptables -t nat -D POSTROUTING -p tcp -m tcp --dport ${port} -j SNAT --to-source ${NSA_LO_IP} -o ${VRF}
+	run_cmd ip6tables -t nat -D POSTROUTING -p tcp -m tcp --dport ${port} -j SNAT --to-source ${NSA_LO_IP6} -o ${VRF}
+}
+
 use_cases()
 {
 	log_section "Use cases"
@@ -3886,6 +3912,8 @@ use_cases()
 	use_case_br
 	log_subsection "Ping LLA with multiple interfaces"
 	use_case_ping_lla_multi
+	log_subsection "SNAT on VRF"
+	use_case_snat_on_vrf
 }
 
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