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selftest: net: Test IPv4 PMTU exceptions with DSCP and ECN 

Add two tests to pmtu.sh, for verifying that PMTU exceptions get
properly created for routes that don't belong to the main table.

A fib-rule based on the packet's DSCP field is used to jump to the
correct table. ECN shouldn't interfere with this process, so each test
has two components: one that only sets DSCP and one that sets both DSCP
and ECN.

One of the test triggers PMTU exceptions using ICMP Echo Requests, the
other using UDP packets (to test different handlers in the kernel).

A few adjustments are necessary in the rest of the script to allow
policy routing scenarios:

  * Add global variable rt_table that allows setup_routing_*() to
    add routes to a specific routing table. By default rt_table is set
    to "main", so existing tests don't need to be modified.

  * Another global variable, policy_mark, is used to define which
    dsfield value is used for policy routing. This variable has no
    effect on tests that don't use policy routing.

  * The UDP version of the test uses socat. So cleanup() now also need
    to kill socat PIDs.

  * route_get_dst_pmtu_from_exception() and route_get_dst_exception()
    now take an optional third argument specifying the dsfield. If
    not specified, 0 is used, so existing users don't need to be
    modified.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Guillaume Nault 2022-03-17 13:45:11 +01:00 committed by Jakub Kicinski
parent 544b4dd568
commit ec730c3e1f
1 changed files with 137 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

141
tools/testing/selftests/net/pmtu.sh
View File

@ -26,6 +26,15 @@
# - pmtu_ipv6
# Same as pmtu_ipv4, except for locked PMTU tests, using IPv6
#
# - pmtu_ipv4_dscp_icmp_exception
# Set up the same network topology as pmtu_ipv4, but use non-default
# routing table in A. A fib-rule is used to jump to this routing table
# based on DSCP. Send ICMPv4 packets with the expected DSCP value and
# verify that ECN doesn't interfere with the creation of PMTU exceptions.
#
# - pmtu_ipv4_dscp_udp_exception
# Same as pmtu_ipv4_dscp_icmp_exception, but use UDP instead of ICMP.
#
# - pmtu_ipv4_vxlan4_exception
# Set up the same network topology as pmtu_ipv4, create a VXLAN tunnel
# over IPv4 between A and B, routed via R1. On the link between R1 and B,
@ -203,6 +212,8 @@ which ping6 > /dev/null 2>&1 && ping6=$(which ping6) || ping6=$(which ping)
tests="
pmtu_ipv4_exception ipv4: PMTU exceptions 1
pmtu_ipv6_exception ipv6: PMTU exceptions 1
pmtu_ipv4_dscp_icmp_exception ICMPv4 with DSCP and ECN: PMTU exceptions 1
pmtu_ipv4_dscp_udp_exception UDPv4 with DSCP and ECN: PMTU exceptions 1
pmtu_ipv4_vxlan4_exception IPv4 over vxlan4: PMTU exceptions 1
pmtu_ipv6_vxlan4_exception IPv6 over vxlan4: PMTU exceptions 1
pmtu_ipv4_vxlan6_exception IPv4 over vxlan6: PMTU exceptions 1
@ -323,6 +334,9 @@ routes_nh="
B 6 default 61
"
policy_mark=0x04
rt_table=main
veth4_a_addr="192.168.1.1"
veth4_b_addr="192.168.1.2"
veth4_c_addr="192.168.2.10"
@ -346,6 +360,7 @@ dummy6_mask="64"
err_buf=
tcpdump_pids=
nettest_pids=
socat_pids=
err() {
err_buf="${err_buf}${1}
@ -723,7 +738,7 @@ setup_routing_old() {
ns_name="$(nsname ${ns})"
ip -n ${ns_name} route add ${addr} via ${gw}
ip -n "${ns_name}" route add "${addr}" table "${rt_table}" via "${gw}"
ns=""; addr=""; gw=""
done
@ -753,7 +768,7 @@ setup_routing_new() {
ns_name="$(nsname ${ns})"
ip -n ${ns_name} -${fam} route add ${addr} nhid ${nhid}
ip -n "${ns_name}" -"${fam}" route add "${addr}" table "${rt_table}" nhid "${nhid}"
ns=""; fam=""; addr=""; nhid=""
done
@ -798,6 +813,24 @@ setup_routing() {
return 0
}
setup_policy_routing() {
setup_routing
ip -netns "${NS_A}" -4 rule add dsfield "${policy_mark}" \
table "${rt_table}"
# Set the IPv4 Don't Fragment bit with tc, since socat doesn't seem to
# have an option do to it.
tc -netns "${NS_A}" qdisc replace dev veth_A-R1 root prio
tc -netns "${NS_A}" qdisc replace dev veth_A-R2 root prio
tc -netns "${NS_A}" filter add dev veth_A-R1 \
protocol ipv4 flower ip_proto udp \
action pedit ex munge ip df set 0x40 pipe csum ip and udp
tc -netns "${NS_A}" filter add dev veth_A-R2 \
protocol ipv4 flower ip_proto udp \
action pedit ex munge ip df set 0x40 pipe csum ip and udp
}
setup_bridge() {
run_cmd ${ns_a} ip link add br0 type bridge || return $ksft_skip
run_cmd ${ns_a} ip link set br0 up
@ -903,6 +936,11 @@ cleanup() {
done
nettest_pids=
for pid in ${socat_pids}; do
kill "${pid}"
done
socat_pids=
for n in ${NS_A} ${NS_B} ${NS_C} ${NS_R1} ${NS_R2}; do
ip netns del ${n} 2> /dev/null
done
@ -950,15 +988,21 @@ link_get_mtu() {
route_get_dst_exception() {
ns_cmd="${1}"
dst="${2}"
dsfield="${3}"
${ns_cmd} ip route get "${dst}"
if [ -z "${dsfield}" ]; then
dsfield=0
fi
${ns_cmd} ip route get "${dst}" dsfield "${dsfield}"
}
route_get_dst_pmtu_from_exception() {
ns_cmd="${1}"
dst="${2}"
dsfield="${3}"
mtu_parse "$(route_get_dst_exception "${ns_cmd}" ${dst})"
mtu_parse "$(route_get_dst_exception "${ns_cmd}" "${dst}" "${dsfield}")"
}
check_pmtu_value() {
@ -1068,6 +1112,95 @@ test_pmtu_ipv6_exception() {
test_pmtu_ipvX 6
}
test_pmtu_ipv4_dscp_icmp_exception() {
rt_table=100
setup namespaces policy_routing || return $ksft_skip
trace "${ns_a}" veth_A-R1 "${ns_r1}" veth_R1-A \
"${ns_r1}" veth_R1-B "${ns_b}" veth_B-R1 \
"${ns_a}" veth_A-R2 "${ns_r2}" veth_R2-A \
"${ns_r2}" veth_R2-B "${ns_b}" veth_B-R2
# Set up initial MTU values
mtu "${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 "${ns_b}" veth_B-R2 1500
len=$((2000 - 20 - 8)) # Fills MTU of veth_A-R1
dst1="${prefix4}.${b_r1}.1"
dst2="${prefix4}.${b_r2}.1"
# Create route exceptions
dsfield=${policy_mark} # No ECN bit set (Not-ECT)
run_cmd "${ns_a}" ping -q -M want -Q "${dsfield}" -c 1 -w 1 -s "${len}" "${dst1}"
dsfield=$(printf "%#x" $((policy_mark + 0x02))) # ECN=2 (ECT(0))
run_cmd "${ns_a}" ping -q -M want -Q "${dsfield}" -c 1 -w 1 -s "${len}" "${dst2}"
# Check that exceptions have been created with the correct PMTU
pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst1}" "${policy_mark}")"
check_pmtu_value "1400" "${pmtu_1}" "exceeding MTU" || return 1
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst2}" "${policy_mark}")"
check_pmtu_value "1500" "${pmtu_2}" "exceeding MTU" || return 1
}
test_pmtu_ipv4_dscp_udp_exception() {
rt_table=100
if ! which socat > /dev/null 2>&1; then
echo "'socat' command not found; skipping tests"
return $ksft_skip
fi
setup namespaces policy_routing || return $ksft_skip
trace "${ns_a}" veth_A-R1 "${ns_r1}" veth_R1-A \
"${ns_r1}" veth_R1-B "${ns_b}" veth_B-R1 \
"${ns_a}" veth_A-R2 "${ns_r2}" veth_R2-A \
"${ns_r2}" veth_R2-B "${ns_b}" veth_B-R2
# Set up initial MTU values
mtu "${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 "${ns_b}" veth_B-R2 1500
len=$((2000 - 20 - 8)) # Fills MTU of veth_A-R1
dst1="${prefix4}.${b_r1}.1"
dst2="${prefix4}.${b_r2}.1"
# Create route exceptions
run_cmd_bg "${ns_b}" socat UDP-LISTEN:50000 OPEN:/dev/null,wronly=1
socat_pids="${socat_pids} $!"
dsfield=${policy_mark} # No ECN bit set (Not-ECT)
run_cmd "${ns_a}" socat OPEN:/dev/zero,rdonly=1,readbytes="${len}" \
UDP:"${dst1}":50000,tos="${dsfield}"
dsfield=$(printf "%#x" $((policy_mark + 0x02))) # ECN=2 (ECT(0))
run_cmd "${ns_a}" socat OPEN:/dev/zero,rdonly=1,readbytes="${len}" \
UDP:"${dst2}":50000,tos="${dsfield}"
# Check that exceptions have been created with the correct PMTU
pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst1}" "${policy_mark}")"
check_pmtu_value "1400" "${pmtu_1}" "exceeding MTU" || return 1
pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst2}" "${policy_mark}")"
check_pmtu_value "1500" "${pmtu_2}" "exceeding MTU" || return 1
}
test_pmtu_ipvX_over_vxlanY_or_geneveY_exception() {
type=${1}
family=${2}