tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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