selftests: pmtu: Introduce tests for IPv4/IPv6 over VXLAN over IPv4/IPv6

Use a router between endpoints, implemented via namespaces, set a low MTU
between router and destination endpoint, exceed it and check PMTU value in
route exceptions.

v2:
- Change all occurrences of VxLAN to VXLAN (Jiri Benc)
- Introduce IPv4 tests right away, if iproute2 doesn't support the 'df'
  link option they will be skipped (David Ahern)
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/pmtu.sh

@@ -26,6 +26,23 @@
 # - pmtu_ipv6
 #	Same as pmtu_ipv4, except for locked PMTU tests, using IPv6
 #
+# - pmtu_ipv4_vxlan4_exception
+#	Set up the same network topology as pmtu_ipv4, create a VXLAN tunnel
+#	over IPv4 between A and B, routed via R1. On the link between R1 and B,
+#	set a MTU lower than the VXLAN MTU and the MTU on the link between A and
+#	R1. Send IPv4 packets, exceeding the MTU between R1 and B, over VXLAN
+#	from A to B and check that the PMTU exception is created with the right
+#	value on A
+#
+# - pmtu_ipv6_vxlan4_exception
+#	Same as pmtu_ipv4_vxlan4_exception, but send IPv6 packets from A to B
+#
+# - pmtu_ipv4_vxlan6_exception
+#	Same as pmtu_ipv4_vxlan4_exception, but use IPv6 transport from A to B
+#
+# - pmtu_ipv6_vxlan6_exception
+#	Same as pmtu_ipv4_vxlan6_exception, but send IPv6 packets from A to B
+#
 # - pmtu_vti4_exception
 #	Set up vti tunnel on top of veth, with xfrm states and policies, in two
 #	namespaces with matching endpoints. Check that route exception is not
@@ -72,6 +89,10 @@ which ping6 > /dev/null 2>&1 && ping6=$(which ping6) || ping6=$(which ping)
 tests="
 	pmtu_ipv4_exception		ipv4: PMTU exceptions
 	pmtu_ipv6_exception		ipv6: PMTU exceptions
+	pmtu_ipv4_vxlan4_exception	IPv4 over vxlan4: PMTU exceptions
+	pmtu_ipv6_vxlan4_exception	IPv6 over vxlan4: PMTU exceptions
+	pmtu_ipv4_vxlan6_exception	IPv4 over vxlan6: PMTU exceptions
+	pmtu_ipv6_vxlan6_exception	IPv6 over vxlan6: PMTU exceptions
 	pmtu_vti6_exception		vti6: PMTU exceptions
 	pmtu_vti4_exception		vti4: PMTU exceptions
 	pmtu_vti4_default_mtu		vti4: default MTU assignment
@@ -95,8 +116,8 @@ ns_r2="ip netns exec ${NS_R2}"
 # Addresses are:
 # - IPv4: PREFIX4.SEGMENT.ID (/24)
 # - IPv6: PREFIX6:SEGMENT::ID (/64)
-prefix4="192.168"
-prefix6="fd00"
+prefix4="10.0"
+prefix6="fc00"
 a_r1=1
 a_r2=2
 b_r1=3
@@ -129,12 +150,12 @@ veth6_a_addr="fd00:1::a"
 veth6_b_addr="fd00:1::b"
 veth6_mask="64"
 
-vti4_a_addr="192.168.2.1"
-vti4_b_addr="192.168.2.2"
-vti4_mask="24"
-vti6_a_addr="fd00:2::a"
-vti6_b_addr="fd00:2::b"
-vti6_mask="64"
+tunnel4_a_addr="192.168.2.1"
+tunnel4_b_addr="192.168.2.2"
+tunnel4_mask="24"
+tunnel6_a_addr="fd00:2::a"
+tunnel6_b_addr="fd00:2::b"
+tunnel6_mask="64"
 
 dummy6_0_addr="fc00:1000::0"
 dummy6_1_addr="fc00:1001::0"
@@ -202,11 +223,39 @@ setup_vti() {
 }
 
 setup_vti4() {
-	setup_vti 4 ${veth4_a_addr} ${veth4_b_addr} ${vti4_a_addr} ${vti4_b_addr} ${vti4_mask}
+	setup_vti 4 ${veth4_a_addr} ${veth4_b_addr} ${tunnel4_a_addr} ${tunnel4_b_addr} ${tunnel4_mask}
 }
 
 setup_vti6() {
-	setup_vti 6 ${veth6_a_addr} ${veth6_b_addr} ${vti6_a_addr} ${vti6_b_addr} ${vti6_mask}
+	setup_vti 6 ${veth6_a_addr} ${veth6_b_addr} ${tunnel6_a_addr} ${tunnel6_b_addr} ${tunnel6_mask}
+}
+
+setup_vxlan() {
+	a_addr="${1}"
+	b_addr="${2}"
+	opts="${3}"
+
+	${ns_a} ip link add vxlan_a type vxlan id 1 local ${a_addr} remote ${b_addr} ttl 64 dstport 4789 ${opts} || return 1
+	${ns_b} ip link add vxlan_b type vxlan id 1 local ${b_addr} remote ${a_addr} ttl 64 dstport 4789 ${opts}
+
+	${ns_a} ip addr add ${tunnel4_a_addr}/${tunnel4_mask}   dev vxlan_a
+	${ns_b} ip addr add ${tunnel4_b_addr}/${tunnel4_mask}   dev vxlan_b
+
+	${ns_a} ip addr add ${tunnel6_a_addr}/${tunnel6_mask}   dev vxlan_a
+	${ns_b} ip addr add ${tunnel6_b_addr}/${tunnel6_mask}   dev vxlan_b
+
+	${ns_a} ip link set vxlan_a up
+	${ns_b} ip link set vxlan_b up
+
+	sleep 1
+}
+
+setup_vxlan4() {
+	setup_vxlan ${prefix4}.${a_r1}.1 ${prefix4}.${b_r1}.1 "df set"
+}
+
+setup_vxlan6() {
+	setup_vxlan ${prefix6}:${a_r1}::1 ${prefix6}:${b_r1}::1 ""
 }
 
 setup_xfrm() {
@@ -465,6 +514,64 @@ test_pmtu_ipv6_exception() {
 	test_pmtu_ipvX 6
 }
 
+test_pmtu_ipvX_over_vxlanY_exception() {
+	family=${1}
+	outer_family=${2}
+	ll_mtu=4000
+
+	if [ ${outer_family} -eq 4 ]; then
+		setup namespaces routing vxlan4 || return 2
+		#                      IPv4 header   UDP header   VXLAN header   Ethernet header
+		exp_mtu=$((${ll_mtu} - 20          - 8          - 8            - 14))
+	else
+		setup namespaces routing vxlan6 || return 2
+		#                      IPv6 header   UDP header   VXLAN header   Ethernet header
+		exp_mtu=$((${ll_mtu} - 40          - 8          - 8            - 14))
+	fi
+
+	trace "${ns_a}" vxlan_a      "${ns_b}"  vxlan_b \
+	      "${ns_a}" veth_A-R1    "${ns_r1}" veth_R1-A \
+	      "${ns_b}" veth_B-R1    "${ns_r1}" veth_R1-B
+
+	if [ ${family} -eq 4 ]; then
+		ping=ping
+		dst=${tunnel4_b_addr}
+	else
+		ping=${ping6}
+		dst=${tunnel6_b_addr}
+	fi
+
+	# Create route exception by exceeding link layer MTU
+	mtu "${ns_a}"  veth_A-R1 $((${ll_mtu} + 1000))
+	mtu "${ns_r1}" veth_R1-A $((${ll_mtu} + 1000))
+	mtu "${ns_b}"  veth_B-R1 ${ll_mtu}
+	mtu "${ns_r1}" veth_R1-B ${ll_mtu}
+
+	mtu "${ns_a}" vxlan_a $((${ll_mtu} + 1000))
+	mtu "${ns_b}" vxlan_b $((${ll_mtu} + 1000))
+	${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
+
+	# Check that exception was created
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"
+	check_pmtu_value ${exp_mtu} "${pmtu}" "exceeding link layer MTU on VXLAN interface"
+}
+
+test_pmtu_ipv4_vxlan4_exception() {
+	test_pmtu_ipvX_over_vxlanY_exception 4 4
+}
+
+test_pmtu_ipv6_vxlan4_exception() {
+	test_pmtu_ipvX_over_vxlanY_exception 6 4
+}
+
+test_pmtu_ipv4_vxlan6_exception() {
+	test_pmtu_ipvX_over_vxlanY_exception 4 6
+}
+
+test_pmtu_ipv6_vxlan6_exception() {
+	test_pmtu_ipvX_over_vxlanY_exception 6 6
+}
+
 test_pmtu_vti4_exception() {
 	setup namespaces veth vti4 xfrm4 || return 2
 	trace "${ns_a}" veth_a    "${ns_b}" veth_b \
@@ -484,14 +591,14 @@ test_pmtu_vti4_exception() {
 
 	# Send DF packet without exceeding link layer MTU, check that no
 	# exception is created
-	${ns_a} ping -q -M want -i 0.1 -w 2 -s ${ping_payload} ${vti4_b_addr} > /dev/null
-	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${vti4_b_addr})"
+	${ns_a} ping -q -M want -i 0.1 -w 2 -s ${ping_payload} ${tunnel4_b_addr} > /dev/null
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel4_b_addr})"
 	check_pmtu_value "" "${pmtu}" "sending packet smaller than PMTU (IP payload length ${esp_payload_rfc4106})" || return 1
 
 	# Now exceed link layer MTU by one byte, check that exception is created
 	# with the right PMTU value
-	${ns_a} ping -q -M want -i 0.1 -w 2 -s $((ping_payload + 1)) ${vti4_b_addr} > /dev/null
-	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${vti4_b_addr})"
+	${ns_a} ping -q -M want -i 0.1 -w 2 -s $((ping_payload + 1)) ${tunnel4_b_addr} > /dev/null
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel4_b_addr})"
 	check_pmtu_value "${esp_payload_rfc4106}" "${pmtu}" "exceeding PMTU (IP payload length $((esp_payload_rfc4106 + 1)))"
 }
 
@@ -506,20 +613,20 @@ test_pmtu_vti6_exception() {
 	mtu "${ns_b}" veth_b 4000
 	mtu "${ns_a}" vti6_a 5000
 	mtu "${ns_b}" vti6_b 5000
-	${ns_a} ${ping6} -q -i 0.1 -w 2 -s 60000 ${vti6_b_addr} > /dev/null
+	${ns_a} ${ping6} -q -i 0.1 -w 2 -s 60000 ${tunnel6_b_addr} > /dev/null
 
 	# Check that exception was created
-	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${vti6_b_addr})"
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel6_b_addr})"
 	check_pmtu_value any "${pmtu}" "creating tunnel exceeding link layer MTU" || return 1
 
 	# Decrease tunnel MTU, check for PMTU decrease in route exception
 	mtu "${ns_a}" vti6_a 3000
-	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${vti6_b_addr})"
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel6_b_addr})"
 	check_pmtu_value "3000" "${pmtu}" "decreasing tunnel MTU" || fail=1
 
 	# Increase tunnel MTU, check for PMTU increase in route exception
 	mtu "${ns_a}" vti6_a 9000
-	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${vti6_b_addr})"
+	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel6_b_addr})"
 	check_pmtu_value "9000" "${pmtu}" "increasing tunnel MTU" || fail=1
 
 	return ${fail}