1#!/bin/bash 2# SPDX-License-Identifier: GPL-2.0 3 4# Test for checking ICMP response with dummy address instead of 0.0.0.0. 5# Sets up two namespaces like: 6# +----------------------+ +--------------------+ 7# | ns1 | v4-via-v6 routes: | ns2 | 8# | | ' | | 9# | +--------+ -> 172.16.1.0/24 -> +--------+ | 10# | | veth0 +--------------------------+ veth0 | | 11# | +--------+ <- 172.16.0.0/24 <- +--------+ | 12# | 172.16.0.1 | | 2001:db8:1::2/64 | 13# | 2001:db8:1::2/64 | | | 14# +----------------------+ +--------------------+ 15# 16# And then tries to ping 172.16.1.1 from ns1. This results in a "net 17# unreachable" message being sent from ns2, but there is no IPv4 address set in 18# that address space, so the kernel should substitute the dummy address 19# 192.0.0.8 defined in RFC7600. 20 21NS1=ns1 22NS2=ns2 23H1_IP=172.16.0.1/32 24H1_IP6=2001:db8:1::1 25RT1=172.16.1.0/24 26PINGADDR=172.16.1.1 27RT2=172.16.0.0/24 28H2_IP6=2001:db8:1::2 29 30TMPFILE=$(mktemp) 31 32cleanup() 33{ 34 rm -f "$TMPFILE" 35 ip netns del $NS1 36 ip netns del $NS2 37} 38 39trap cleanup EXIT 40 41# Namespaces 42ip netns add $NS1 43ip netns add $NS2 44 45# Connectivity 46ip -netns $NS1 link add veth0 type veth peer name veth0 netns $NS2 47ip -netns $NS1 link set dev veth0 up 48ip -netns $NS2 link set dev veth0 up 49ip -netns $NS1 addr add $H1_IP dev veth0 50ip -netns $NS1 addr add $H1_IP6/64 dev veth0 nodad 51ip -netns $NS2 addr add $H2_IP6/64 dev veth0 nodad 52ip -netns $NS1 route add $RT1 via inet6 $H2_IP6 53ip -netns $NS2 route add $RT2 via inet6 $H1_IP6 54 55# Make sure ns2 will respond with ICMP unreachable 56ip netns exec $NS2 sysctl -qw net.ipv4.icmp_ratelimit=0 net.ipv4.ip_forward=1 57 58# Run the test - a ping runs in the background, and we capture ICMP responses 59# with tcpdump; -c 1 means it should exit on the first ping, but add a timeout 60# in case something goes wrong 61ip netns exec $NS1 ping -w 3 -i 0.5 $PINGADDR >/dev/null & 62ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>/dev/null 63 64# Parse response and check for dummy address 65# tcpdump output looks like: 66# IP 192.0.0.8 > 172.16.0.1: ICMP net 172.16.1.1 unreachable, length 92 67RESP_IP=$(awk '{print $2}' < $TMPFILE) 68if [[ "$RESP_IP" != "192.0.0.8" ]]; then 69 echo "FAIL - got ICMP response from $RESP_IP, should be 192.0.0.8" 70 exit 1 71else 72 echo "OK" 73 exit 0 74fi 75