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selftests: net: Introduce first PMTU test
One single test implemented so far: test_pmtu_vti6_exception checks that the PMTU of a route exception, caused by a tunnel exceeding the link layer MTU, is affected by administrative changes of the tunnel MTU. Creation of the route exception is checked too. Requested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Acked-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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‎tools/testing/selftests/net/Makefile

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@@ -5,7 +5,7 @@ CFLAGS = -Wall -Wl,--no-as-needed -O2 -g
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CFLAGS += -I../../../../usr/include/
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TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh rtnetlink.sh
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TEST_PROGS += fib_tests.sh fib-onlink-tests.sh
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TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh
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TEST_GEN_FILES = socket
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TEST_GEN_FILES += psock_fanout psock_tpacket msg_zerocopy
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TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa

‎tools/testing/selftests/net/pmtu.sh

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#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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#
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# Check that route PMTU values match expectations
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#
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# Tests currently implemented:
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#
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# - test_pmtu_vti6_exception
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# Set up vti6 tunnel on top of veth, with xfrm states and policies, in two
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# namespaces with matching endpoints. Check that route exception is
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# created by exceeding link layer MTU with ping to other endpoint. Then
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# decrease and increase MTU of tunnel, checking that route exception PMTU
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# changes accordingly
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NS_A="ns-$(mktemp -u XXXXXX)"
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NS_B="ns-$(mktemp -u XXXXXX)"
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ns_a="ip netns exec ${NS_A}"
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ns_b="ip netns exec ${NS_B}"
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veth6_a_addr="fd00:1::a"
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veth6_b_addr="fd00:1::b"
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veth6_mask="64"
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vti6_a_addr="fd00:2::a"
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vti6_b_addr="fd00:2::b"
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vti6_mask="64"
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setup_namespaces() {
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ip netns add ${NS_A} || return 0
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ip netns add ${NS_B}
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return 1
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}
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setup_veth() {
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${ns_a} ip link add veth_a type veth peer name veth_b || return 0
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${ns_a} ip link set veth_b netns ${NS_B}
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${ns_a} ip addr add ${veth6_a_addr}/${veth6_mask} dev veth_a
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${ns_b} ip addr add ${veth6_b_addr}/${veth6_mask} dev veth_b
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${ns_a} ip link set veth_a up
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${ns_b} ip link set veth_b up
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return 1
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}
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setup_vti6() {
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${ns_a} ip link add vti_a type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10 || return 0
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${ns_b} ip link add vti_b type vti6 local ${veth6_b_addr} remote ${veth6_a_addr} key 10
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${ns_a} ip addr add ${vti6_a_addr}/${vti6_mask} dev vti_a
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${ns_b} ip addr add ${vti6_b_addr}/${vti6_mask} dev vti_b
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${ns_a} ip link set vti_a up
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${ns_b} ip link set vti_b up
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sleep 1
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return 1
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}
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setup_xfrm() {
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${ns_a} ip -6 xfrm state add src ${veth6_a_addr} dst ${veth6_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel || return 0
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${ns_a} ip -6 xfrm state add src ${veth6_b_addr} dst ${veth6_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
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${ns_a} ip -6 xfrm policy add dir out mark 10 tmpl src ${veth6_a_addr} dst ${veth6_b_addr} proto esp mode tunnel
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${ns_a} ip -6 xfrm policy add dir in mark 10 tmpl src ${veth6_b_addr} dst ${veth6_a_addr} proto esp mode tunnel
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${ns_b} ip -6 xfrm state add src ${veth6_a_addr} dst ${veth6_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
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${ns_b} ip -6 xfrm state add src ${veth6_b_addr} dst ${veth6_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
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${ns_b} ip -6 xfrm policy add dir out mark 10 tmpl src ${veth6_b_addr} dst ${veth6_a_addr} proto esp mode tunnel
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${ns_b} ip -6 xfrm policy add dir in mark 10 tmpl src ${veth6_a_addr} dst ${veth6_b_addr} proto esp mode tunnel
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return 1
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}
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setup() {
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tunnel_type="$1"
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[ "$(id -u)" -ne 0 ] && echo "SKIP: need to run as root" && exit 0
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setup_namespaces && echo "SKIP: namespaces not supported" && exit 0
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setup_veth && echo "SKIP: veth not supported" && exit 0
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case ${tunnel_type} in
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"vti6")
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setup_vti6 && echo "SKIP: vti6 not supported" && exit 0
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setup_xfrm && echo "SKIP: xfrm not supported" && exit 0
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;;
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*)
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;;
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esac
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}
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cleanup() {
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ip netns del ${NS_A} 2 > /dev/null
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ip netns del ${NS_B} 2 > /dev/null
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}
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mtu() {
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ns_cmd="${1}"
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dev="${2}"
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mtu="${3}"
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${ns_cmd} ip link set dev ${dev} mtu ${mtu}
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}
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route_get_dst_exception() {
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dst="${1}"
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${ns_a} ip route get "${dst}"
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}
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route_get_dst_pmtu_from_exception() {
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dst="${1}"
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exception="$(route_get_dst_exception ${dst})"
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next=0
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for i in ${exception}; do
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[ ${next} -eq 1 ] && echo "${i}" && return
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[ "${i}" = "mtu" ] && next=1
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done
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}
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test_pmtu_vti6_exception() {
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setup vti6
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# Create route exception by exceeding link layer MTU
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mtu "${ns_a}" veth_a 4000
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mtu "${ns_b}" veth_b 4000
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mtu "${ns_a}" vti_a 5000
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mtu "${ns_b}" vti_b 5000
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${ns_a} ping6 -q -i 0.1 -w 2 -s 60000 ${vti6_b_addr} > /dev/null
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# Check that exception was created
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if [ "$(route_get_dst_pmtu_from_exception ${vti6_b_addr})" = "" ]; then
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echo "FAIL: Tunnel exceeding link layer MTU didn't create route exception"
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exit 1
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fi
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# Decrease tunnel MTU, check for PMTU decrease in route exception
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mtu "${ns_a}" vti_a 3000
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if [ "$(route_get_dst_pmtu_from_exception ${vti6_b_addr})" -ne 3000 ]; then
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echo "FAIL: Decreasing tunnel MTU didn't decrease route exception PMTU"
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exit 1
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fi
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# Increase tunnel MTU, check for PMTU increase in route exception
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mtu "${ns_a}" vti_a 9000
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if [ "$(route_get_dst_pmtu_from_exception ${vti6_b_addr})" -ne 9000 ]; then
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echo "FAIL: Increasing tunnel MTU didn't increase route exception PMTU"
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exit 1
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fi
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echo "PASS"
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}
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trap cleanup EXIT
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test_pmtu_vti6_exception
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exit 0

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