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selftests: pmtu: add basic IPv4 and IPv6 PMTU tests
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Commit d1f1b9c ("selftests: net: Introduce first PMTU test") and
follow-ups introduced some PMTU tests, but they all rely on tunneling,
and, particularly, on VTI.

These new tests use simple routing to exercise the generation and
update of PMTU exceptions in IPv4 and IPv6.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Sabrina Dubroca authored and David S. Miller committed Oct 8, 2018
1 parent 72ebddd commit e44e428
Showing 1 changed file with 203 additions and 4 deletions.
207 changes: 203 additions & 4 deletions tools/testing/selftests/net/pmtu.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,26 @@
#
# Tests currently implemented:
#
# - pmtu_ipv4
# Set up two namespaces, A and B, with two paths between them over routers
# R1 and R2 (also implemented with namespaces), with different MTUs:
#
# segment a_r1 segment b_r1 a_r1: 2000
# .--------------R1--------------. a_r2: 1500
# A B a_r3: 2000
# '--------------R2--------------' a_r4: 1400
# segment a_r2 segment b_r2
#
# Check that PMTU exceptions with the correct PMTU are created. Then
# decrease and increase the MTU of the local link for one of the paths,
# A to R1, checking that route exception PMTU changes accordingly over
# this path. Also check that locked exceptions are created when an ICMP
# message advertising a PMTU smaller than net.ipv4.route.min_pmtu is
# received
#
# - pmtu_ipv6
# Same as pmtu_ipv4, except for locked PMTU tests, using IPv6
#
# - 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
Expand Down Expand Up @@ -50,6 +70,8 @@ ksft_skip=4
which ping6 > /dev/null 2>&1 && ping6=$(which ping6) || ping6=$(which ping)

tests="
pmtu_ipv4_exception ipv4: PMTU exceptions
pmtu_ipv6_exception ipv6: PMTU exceptions
pmtu_vti6_exception vti6: PMTU exceptions
pmtu_vti4_exception vti4: PMTU exceptions
pmtu_vti4_default_mtu vti4: default MTU assignment
Expand All @@ -60,8 +82,45 @@ tests="

NS_A="ns-$(mktemp -u XXXXXX)"
NS_B="ns-$(mktemp -u XXXXXX)"
NS_R1="ns-$(mktemp -u XXXXXX)"
NS_R2="ns-$(mktemp -u XXXXXX)"
ns_a="ip netns exec ${NS_A}"
ns_b="ip netns exec ${NS_B}"
ns_r1="ip netns exec ${NS_R1}"
ns_r2="ip netns exec ${NS_R2}"

# Addressing and routing for tests with routers: four network segments, with
# index SEGMENT between 1 and 4, a common prefix (PREFIX4 or PREFIX6) and an
# identifier ID, which is 1 for hosts (A and B), 2 for routers (R1 and R2).
# Addresses are:
# - IPv4: PREFIX4.SEGMENT.ID (/24)
# - IPv6: PREFIX6:SEGMENT::ID (/64)
prefix4="192.168"
prefix6="fd00"
a_r1=1
a_r2=2
b_r1=3
b_r2=4
# ns peer segment
routing_addrs="
A R1 ${a_r1}
A R2 ${a_r2}
B R1 ${b_r1}
B R2 ${b_r2}
"
# Traffic from A to B goes through R1 by default, and through R2, if destined to
# B's address on the b_r2 segment.
# Traffic from B to A goes through R1.
# ns destination gateway
routes="
A default ${prefix4}.${a_r1}.2
A ${prefix4}.${b_r2}.1 ${prefix4}.${a_r2}.2
B default ${prefix4}.${b_r1}.2
A default ${prefix6}:${a_r1}::2
A ${prefix6}:${b_r2}::1 ${prefix6}:${a_r2}::2
B default ${prefix6}:${b_r1}::2
"

veth4_a_addr="192.168.1.1"
veth4_b_addr="192.168.1.2"
Expand Down Expand Up @@ -94,9 +153,15 @@ err_flush() {
err_buf=
}

# Find the auto-generated name for this namespace
nsname() {
eval echo \$NS_$1
}

setup_namespaces() {
ip netns add ${NS_A} || return 1
ip netns add ${NS_B}
for n in ${NS_A} ${NS_B} ${NS_R1} ${NS_R2}; do
ip netns add ${n} || return 1
done
}

setup_veth() {
Expand Down Expand Up @@ -167,6 +232,49 @@ setup_xfrm6() {
setup_xfrm 6 ${veth6_a_addr} ${veth6_b_addr}
}

setup_routing() {
for i in ${NS_R1} ${NS_R2}; do
ip netns exec ${i} sysctl -q net/ipv4/ip_forward=1
ip netns exec ${i} sysctl -q net/ipv6/conf/all/forwarding=1
done

for i in ${routing_addrs}; do
[ "${ns}" = "" ] && ns="${i}" && continue
[ "${peer}" = "" ] && peer="${i}" && continue
[ "${segment}" = "" ] && segment="${i}"

ns_name="$(nsname ${ns})"
peer_name="$(nsname ${peer})"
if="veth_${ns}-${peer}"
ifpeer="veth_${peer}-${ns}"

# Create veth links
ip link add ${if} up netns ${ns_name} type veth peer name ${ifpeer} netns ${peer_name} || return 1
ip -n ${peer_name} link set dev ${ifpeer} up

# Add addresses
ip -n ${ns_name} addr add ${prefix4}.${segment}.1/24 dev ${if}
ip -n ${ns_name} addr add ${prefix6}:${segment}::1/64 dev ${if}

ip -n ${peer_name} addr add ${prefix4}.${segment}.2/24 dev ${ifpeer}
ip -n ${peer_name} addr add ${prefix6}:${segment}::2/64 dev ${ifpeer}

ns=""; peer=""; segment=""
done

for i in ${routes}; do
[ "${ns}" = "" ] && ns="${i}" && continue
[ "${addr}" = "" ] && addr="${i}" && continue
[ "${gw}" = "" ] && gw="${i}"

ns_name="$(nsname ${ns})"

ip -n ${ns_name} route add ${addr} via ${gw}

ns=""; addr=""; gw=""
done
}

setup() {
[ "$(id -u)" -ne 0 ] && echo " need to run as root" && return $ksft_skip

Expand All @@ -178,8 +286,9 @@ setup() {

cleanup() {
[ ${cleanup_done} -eq 1 ] && return
ip netns del ${NS_A} 2> /dev/null
ip netns del ${NS_B} 2> /dev/null
for n in ${NS_A} ${NS_B} ${NS_R1} ${NS_R2}; do
ip netns del ${n} 2> /dev/null
done
cleanup_done=1
}

Expand Down Expand Up @@ -244,6 +353,96 @@ check_pmtu_value() {
return 1
}

test_pmtu_ipvX() {
family=${1}

setup namespaces routing || return 2

if [ ${family} -eq 4 ]; then
ping=ping
dst1="${prefix4}.${b_r1}.1"
dst2="${prefix4}.${b_r2}.1"
else
ping=${ping6}
dst1="${prefix6}:${b_r1}::1"
dst2="${prefix6}:${b_r2}::1"
fi

# Set up initial MTU values
mtu "${ns_a}" veth_A-R1 2000
mtu "${ns_r1}" veth_R1-A 2000
mtu "${ns_r1}" veth_R1-B 1400
mtu "${ns_b}" veth_B-R1 1400

mtu "${ns_a}" veth_A-R2 2000
mtu "${ns_r2}" veth_R2-A 2000
mtu "${ns_r2}" veth_R2-B 1500
mtu "${ns_b}" veth_B-R2 1500

# Create route exceptions
${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1800 ${dst1} > /dev/null
${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1800 ${dst2} > /dev/null

# Check that exceptions have been created with the correct PMTU
pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst1})"
check_pmtu_value "1400" "${pmtu_1}" "exceeding MTU" || return 1
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "1500" "${pmtu_2}" "exceeding MTU" || return 1

# Decrease local MTU below PMTU, check for PMTU decrease in route exception
mtu "${ns_a}" veth_A-R1 1300
mtu "${ns_r1}" veth_R1-A 1300
pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst1})"
check_pmtu_value "1300" "${pmtu_1}" "decreasing local MTU" || return 1
# Second exception shouldn't be modified
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "1500" "${pmtu_2}" "changing local MTU on a link not on this path" || return 1

# Increase MTU, check for PMTU increase in route exception
mtu "${ns_a}" veth_A-R1 1700
mtu "${ns_r1}" veth_R1-A 1700
pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst1})"
check_pmtu_value "1700" "${pmtu_1}" "increasing local MTU" || return 1
# Second exception shouldn't be modified
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "1500" "${pmtu_2}" "changing local MTU on a link not on this path" || return 1

# Skip PMTU locking tests for IPv6
[ $family -eq 6 ] && return 0

# Decrease remote MTU on path via R2, get new exception
mtu "${ns_r2}" veth_R2-B 400
mtu "${ns_b}" veth_B-R2 400
${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1400 ${dst2} > /dev/null
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1

# Decrease local MTU below PMTU
mtu "${ns_a}" veth_A-R2 500
mtu "${ns_r2}" veth_R2-A 500
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "500" "${pmtu_2}" "decreasing local MTU" || return 1

# Increase local MTU
mtu "${ns_a}" veth_A-R2 1500
mtu "${ns_r2}" veth_R2-A 1500
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "1500" "${pmtu_2}" "increasing local MTU" || return 1

# Get new exception
${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1400 ${dst2} > /dev/null
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1
}

test_pmtu_ipv4_exception() {
test_pmtu_ipvX 4
}

test_pmtu_ipv6_exception() {
test_pmtu_ipvX 6
}

test_pmtu_vti4_exception() {
setup namespaces veth vti4 xfrm4 || return 2

Expand Down

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