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 21source lib.sh 22 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 cleanup_ns $NS1 $NS2 36} 37 38trap cleanup EXIT 39 40# Namespaces 41setup_ns NS1 NS2 42 43# Connectivity 44ip -netns $NS1 link add veth0 type veth peer name veth0 netns $NS2 45ip -netns $NS1 link set dev veth0 up 46ip -netns $NS2 link set dev veth0 up 47ip -netns $NS1 addr add $H1_IP dev veth0 48ip -netns $NS1 addr add $H1_IP6/64 dev veth0 nodad 49ip -netns $NS2 addr add $H2_IP6/64 dev veth0 nodad 50ip -netns $NS1 route add $RT1 via inet6 $H2_IP6 51ip -netns $NS2 route add $RT2 via inet6 $H1_IP6 52 53# Make sure ns2 will respond with ICMP unreachable 54ip netns exec $NS2 sysctl -qw net.ipv4.icmp_ratelimit=0 net.ipv4.ip_forward=1 55 56# Run the test - a ping runs in the background, and we capture ICMP responses 57# with tcpdump; -c 1 means it should exit on the first ping, but add a timeout 58# in case something goes wrong 59ip netns exec $NS1 ping -w 3 -i 0.5 $PINGADDR >/dev/null & 60ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>/dev/null 61 62# Parse response and check for dummy address 63# tcpdump output looks like: 64# IP 192.0.0.8 > 172.16.0.1: ICMP net 172.16.1.1 unreachable, length 92 65RESP_IP=$(awk '{print $2}' < $TMPFILE) 66if [[ "$RESP_IP" != "192.0.0.8" ]]; then 67 echo "FAIL - got ICMP response from $RESP_IP, should be 192.0.0.8" 68 exit 1 69else 70 echo "OK" 71 exit 0 72fi 73