[PATCH 5.15 034/171] selftests: netfilter: add a vrf+conntrack testcase

Greg Kroah-Hartman
2021-12-13T10:01:39Z

From: Florian Westphal <fw@strlen.de>

commit 33b8aad21ac175eba9577a73eb62b0aa141c241c upstream.

Rework the reproducer for the vrf+conntrack regression reported
by Eugene into a selftest and also add a test for ip masquerading
that Lahav fixed recently.

With net or net-next tree, the first test fails and the latter
two pass.

With 09e856d54bda5f28 ("vrf: Reset skb conntrack connection on VRF rcv")
reverted first test passes but the last two fail.

A proper fix needs more work, for time being a revert seems to be
the best choice, snat/masquerade did not work before the fix.

Link: https://lore.kernel.org/netdev/378ca299-4474-7e9a-3d36-2350c8c98995@gmail.com/T/#m95358a31810df7392f541f99d187227bc75c9963
Reported-by: Eugene Crosser <crosser@average.org>
Cc: Lahav Schlesinger <lschlesinger@drivenets.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/netfilter/Makefile | 3
tools/testing/selftests/netfilter/conntrack_vrf.sh | 219 +++++++++++++++++++++
2 files changed, 221 insertions(+), 1 deletion(-)
create mode 100755 tools/testing/selftests/netfilter/conntrack_vrf.sh

--- a/tools/testing/selftests/netfilter/Makefile
+++ b/tools/testing/selftests/netfilter/Makefile
@@ -5,7 +5,8 @@ TEST_PROGS := nft_trans_stress.sh nft_fi
conntrack_icmp_related.sh nft_flowtable.sh ipvs.sh \
nft_concat_range.sh nft_conntrack_helper.sh \
nft_queue.sh nft_meta.sh nf_nat_edemux.sh \
- ipip-conntrack-mtu.sh conntrack_tcp_unreplied.sh
+ ipip-conntrack-mtu.sh conntrack_tcp_unreplied.sh \
+ conntrack_vrf.sh

LDLIBS = -lmnl
TEST_GEN_FILES = nf-queue
--- /dev/null
+++ b/tools/testing/selftests/netfilter/conntrack_vrf.sh
@@ -0,0 +1,219 @@
+#!/bin/sh
+
+# This script demonstrates interaction of conntrack and vrf.
+# The vrf driver calls the netfilter hooks again, with oif/iif
+# pointing at the VRF device.
+#
+# For ingress, this means first iteration has iifname of lower/real
+# device. In this script, thats veth0.
+# Second iteration is iifname set to vrf device, tvrf in this script.
+#
+# For egress, this is reversed: first iteration has the vrf device,
+# second iteration is done with the lower/real/veth0 device.
+#
+# test_ct_zone_in demonstrates unexpected change of nftables
+# behavior # caused by commit 09e856d54bda5f28 "vrf: Reset skb conntrack
+# connection on VRF rcv"
+#
+# It was possible to assign conntrack zone to a packet (or mark it for
+# `notracking`) in the prerouting chain before conntrack, based on real iif.
+#
+# After the change, the zone assignment is lost and the zone is assigned based
+# on the VRF master interface (in case such a rule exists).
+# assignment is lost. Instead, assignment based on the `iif` matching
+# Thus it is impossible to distinguish packets based on the original
+# interface.
+#
+# test_masquerade_vrf and test_masquerade_veth0 demonstrate the problem
+# that was supposed to be fixed by the commit mentioned above to make sure
+# that any fix to test case 1 won't break masquerade again.
+
+ksft_skip=4
+
+IP0=172.30.30.1
+IP1=172.30.30.2
+PFXL=30
+ret=0
+
+sfx=$(mktemp -u "XXXXXXXX")
+ns0="ns0-$sfx"
+ns1="ns1-$sfx"
+
+cleanup()
+{
+ ip netns pids $ns0 | xargs kill 2>/dev/null
+ ip netns pids $ns1 | xargs kill 2>/dev/null
+
+ ip netns del $ns0 $ns1
+}
+
+nft --version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not run test without nft tool"
+ exit $ksft_skip
+fi
+
+ip -Version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not run test without ip tool"
+ exit $ksft_skip
+fi
+
+ip netns add "$ns0"
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not create net namespace $ns0"
+ exit $ksft_skip
+fi
+ip netns add "$ns1"
+
+trap cleanup EXIT
+
+ip netns exec $ns0 sysctl -q -w net.ipv4.conf.default.rp_filter=0
+ip netns exec $ns0 sysctl -q -w net.ipv4.conf.all.rp_filter=0
+ip netns exec $ns0 sysctl -q -w net.ipv4.conf.all.rp_filter=0
+
+ip link add veth0 netns "$ns0" type veth peer name veth0 netns "$ns1" > /dev/null 2>&1
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not add veth device"
+ exit $ksft_skip
+fi
+
+ip -net $ns0 li add tvrf type vrf table 9876
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not add vrf device"
+ exit $ksft_skip
+fi
+
+ip -net $ns0 li set lo up
+
+ip -net $ns0 li set veth0 master tvrf
+ip -net $ns0 li set tvrf up
+ip -net $ns0 li set veth0 up
+ip -net $ns1 li set veth0 up
+
+ip -net $ns0 addr add $IP0/$PFXL dev veth0
+ip -net $ns1 addr add $IP1/$PFXL dev veth0
+
+ip netns exec $ns1 iperf3 -s > /dev/null 2>&1&
+if [ $? -ne 0 ];then
+ echo "SKIP: Could not start iperf3"
+ exit $ksft_skip
+fi
+
+# test vrf ingress handling.
+# The incoming connection should be placed in conntrack zone 1,
+# as decided by the first iteration of the ruleset.
+test_ct_zone_in()
+{
+ip netns exec $ns0 nft -f - <<EOF
+table testct {
+ chain rawpre {
+ type filter hook prerouting priority raw;
+
+ iif { veth0, tvrf } counter meta nftrace set 1
+ iif veth0 counter ct zone set 1 counter return
+ iif tvrf counter ct zone set 2 counter return
+ ip protocol icmp counter
+ notrack counter
+ }
+
+ chain rawout {
+ type filter hook output priority raw;
+
+ oif veth0 counter ct zone set 1 counter return
+ oif tvrf counter ct zone set 2 counter return
+ notrack counter
+ }
+}
+EOF
+ ip netns exec $ns1 ping -W 1 -c 1 -I veth0 $IP0 > /dev/null
+
+ # should be in zone 1, not zone 2
+ count=$(ip netns exec $ns0 conntrack -L -s $IP1 -d $IP0 -p icmp --zone 1 2>/dev/null | wc -l)
+ if [ $count -eq 1 ]; then
+ echo "PASS: entry found in conntrack zone 1"
+ else
+ echo "FAIL: entry not found in conntrack zone 1"
+ count=$(ip netns exec $ns0 conntrack -L -s $IP1 -d $IP0 -p icmp --zone 2 2> /dev/null | wc -l)
+ if [ $count -eq 1 ]; then
+ echo "FAIL: entry found in zone 2 instead"
+ else
+ echo "FAIL: entry not in zone 1 or 2, dumping table"
+ ip netns exec $ns0 conntrack -L
+ ip netns exec $ns0 nft list ruleset
+ fi
+ fi
+}
+
+# add masq rule that gets evaluated w. outif set to vrf device.
+# This tests the first iteration of the packet through conntrack,
+# oifname is the vrf device.
+test_masquerade_vrf()
+{
+ ip netns exec $ns0 conntrack -F 2>/dev/null
+
+ip netns exec $ns0 nft -f - <<EOF
+flush ruleset
+table ip nat {
+ chain postrouting {
+ type nat hook postrouting priority 0;
+ # NB: masquerade should always be combined with 'oif(name) bla',
+ # lack of this is intentional here, we want to exercise double-snat.
+ ip saddr 172.30.30.0/30 counter masquerade random
+ }
+}
+EOF
+ ip netns exec $ns0 ip vrf exec tvrf iperf3 -t 1 -c $IP1 >/dev/null
+ if [ $? -ne 0 ]; then
+ echo "FAIL: iperf3 connect failure with masquerade + sport rewrite on vrf device"
+ ret=1
+ return
+ fi
+
+ # must also check that nat table was evaluated on second (lower device) iteration.
+ ip netns exec $ns0 nft list table ip nat |grep -q 'counter packets 2'
+ if [ $? -eq 0 ]; then
+ echo "PASS: iperf3 connect with masquerade + sport rewrite on vrf device"
+ else
+ echo "FAIL: vrf masq rule has unexpected counter value"
+ ret=1
+ fi
+}
+
+# add masq rule that gets evaluated w. outif set to veth device.
+# This tests the 2nd iteration of the packet through conntrack,
+# oifname is the lower device (veth0 in this case).
+test_masquerade_veth()
+{
+ ip netns exec $ns0 conntrack -F 2>/dev/null
+ip netns exec $ns0 nft -f - <<EOF
+flush ruleset
+table ip nat {
+ chain postrouting {
+ type nat hook postrouting priority 0;
+ meta oif veth0 ip saddr 172.30.30.0/30 counter masquerade random
+ }
+}
+EOF
+ ip netns exec $ns0 ip vrf exec tvrf iperf3 -t 1 -c $IP1 > /dev/null
+ if [ $? -ne 0 ]; then
+ echo "FAIL: iperf3 connect failure with masquerade + sport rewrite on veth device"
+ ret=1
+ return
+ fi
+
+ # must also check that nat table was evaluated on second (lower device) iteration.
+ ip netns exec $ns0 nft list table ip nat |grep -q 'counter packets 2'
+ if [ $? -eq 0 ]; then
+ echo "PASS: iperf3 connect with masquerade + sport rewrite on veth device"
+ else
+ echo "FAIL: vrf masq rule has unexpected counter value"
+ ret=1
+ fi
+}
+
+test_ct_zone_in
+test_masquerade_vrf
+test_masquerade_veth
+
+exit $ret