Netdev List

* [PATCH net-next 6/9] selftests: pmtu: Add pmtu_vti4_exception test
From: Stefano Brivio @ 2018-03-15 16:18 UTC (permalink / raw)
  To: David S . Miller; +Cc: Sabrina Dubroca, Steffen Klassert, netdev
In-Reply-To: <cover.1521129192.git.sbrivio@redhat.com>

This test checks that PMTU exceptions are created only when
needed on IPv4 routes with vti and xfrm, and their PMTU value is
checked as well.

We can't adopt the same approach as test_pmtu_vti6_exception()
here, because on IPv4 administrative MTU changes won't be
reflected directly on PMTU.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 tools/testing/selftests/net/pmtu.sh | 84 ++++++++++++++++++++++++++++++++-----
 1 file changed, 74 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
index 67b77f9108ee..336b8545c4bd 100755
--- a/tools/testing/selftests/net/pmtu.sh
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -6,6 +6,14 @@
 #
 # Tests currently implemented:
 #
+# - 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
+#	created if link layer MTU is not exceeded, then exceed it and check that
+#	exception is created with the expected PMTU. The approach described
+#	below for IPv6 doesn't apply here, because, on IPv4, administrative MTU
+#	changes alone won't affect PMTU
+#
 # - pmtu_vti6_exception
 #	Set up vti6 tunnel on top of veth, with xfrm states and policies, in two
 #	namespaces with matching endpoints. Check that route exception is
@@ -22,7 +30,8 @@
 # - pmtu_vti6_default_mtu
 #	Same as above, for IPv6
 
-tests="pmtu_vti6_exception pmtu_vti4_default_mtu pmtu_vti6_default_mtu"
+tests="pmtu_vti4_exception pmtu_vti6_exception
+       pmtu_vti4_default_mtu pmtu_vti6_default_mtu"
 
 NS_A="ns-$(mktemp -u XXXXXX)"
 NS_B="ns-$(mktemp -u XXXXXX)"
@@ -103,19 +112,33 @@ setup_vti6() {
 }
 
 setup_xfrm() {
-	${ns_a} ip -6 xfrm state add src ${veth6_a_addr} dst ${veth6_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel || return 0
-	${ns_a} ip -6 xfrm state add src ${veth6_b_addr} dst ${veth6_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_a} ip -6 xfrm policy add dir out mark 10 tmpl src ${veth6_a_addr} dst ${veth6_b_addr} proto esp mode tunnel
-	${ns_a} ip -6 xfrm policy add dir in mark 10 tmpl src ${veth6_b_addr} dst ${veth6_a_addr} proto esp mode tunnel
+	proto=${1}
+	veth_a_addr="${2}"
+	veth_b_addr="${3}"
 
-	${ns_b} ip -6 xfrm state add src ${veth6_a_addr} dst ${veth6_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_b} ip -6 xfrm state add src ${veth6_b_addr} dst ${veth6_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_b} ip -6 xfrm policy add dir out mark 10 tmpl src ${veth6_b_addr} dst ${veth6_a_addr} proto esp mode tunnel
-	${ns_b} ip -6 xfrm policy add dir in mark 10 tmpl src ${veth6_a_addr} dst ${veth6_b_addr} proto esp mode tunnel
+	${ns_a} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel || return 0
+	${ns_a} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
+	${ns_a} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel
+	${ns_a} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel
+
+	${ns_b} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
+	${ns_b} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
+	${ns_b} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel
+	${ns_b} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel
 
 	return 1
 }
 
+setup_xfrm4() {
+	setup_xfrm 4 ${veth4_a_addr} ${veth4_b_addr}
+	return $?
+}
+
+setup_xfrm6() {
+	setup_xfrm 6 ${veth6_a_addr} ${veth6_b_addr}
+	return $?
+}
+
 setup() {
 	[ "$(id -u)" -ne 0 ] && echo "  need to run as root" && return 0
 
@@ -180,8 +203,49 @@ route_get_dst_pmtu_from_exception() {
 	mtu_parse "$(route_get_dst_exception "${ns_cmd}" ${dst})"
 }
 
+test_pmtu_vti4_exception() {
+	setup namespaces veth vti4 xfrm4 && return 2
+
+	veth_mtu=1500
+	vti_mtu=$((veth_mtu - 20))
+
+	#                                SPI   SN   IV  ICV   pad length   next header
+	esp_payload_rfc4106=$((vti_mtu - 4   - 4  - 8 - 16  - 1          - 1))
+	ping_payload=$((esp_payload_rfc4106 - 28))
+
+	mtu "${ns_a}" veth_a ${veth_mtu}
+	mtu "${ns_b}" veth_b ${veth_mtu}
+	mtu "${ns_a}" vti4_a ${vti_mtu}
+	mtu "${ns_b}" vti4_b ${vti_mtu}
+
+	# 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}" ${vti4_b_addr})"
+	if [ "${pmtu}" != "" ]; then
+		echo "  unexpected exception created with PMTU ${pmtu} for IP payload length ${esp_payload_rfc4106}"
+		return 0
+	fi
+
+	# Now exceed link layer MTU by one byte, check that exception is created
+	${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}" ${vti4_b_addr})"
+	if [ "${pmtu}" = "" ]; then
+		echo "  exception not created for IP payload length $((esp_payload_rfc4106 + 1))"
+		return 0
+	fi
+
+	# ...with the right PMTU value
+	if [ ${pmtu} -ne ${esp_payload_rfc4106} ]; then
+		echo "  wrong PMTU ${pmtu} in exception, expected: ${esp_payload_rfc4106}"
+		return 0
+	fi
+
+	return 1
+}
+
 test_pmtu_vti6_exception() {
-	setup namespaces veth vti6 xfrm && return 2
+	setup namespaces veth vti6 xfrm6 && return 2
 
 	# Create route exception by exceeding link layer MTU
 	mtu "${ns_a}" veth_a 4000
-- 
2.15.1

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