[ovs-dev] [PATCH] conntrack: Add a test for IPv4 UDP zero checksum

Aaron Conole aconole at redhat.com
Wed Feb 10 19:45:06 UTC 2021


Flavio Leitner <fbl at sysclose.org> writes:

> On Wed, Feb 10, 2021 at 11:49:33AM -0500, Aaron Conole wrote:
>> Recently, during some conntrack testing a bug was uncovered in a DPDK
>> PMD, which doesn't support an IPv4 packet with a zero checksum value.
>> In order to show that the connection tracking code in userspace
>> supports IPv4 UDP with a zero checksum, add a test case to enforce
>> this behavior.
>> 
>> Reported-at: http://mails.dpdk.org/archives/dev/2021-January/198528.html
>> Reported-by: Paolo Valerio <pvalerio at redhat.com>
>> Signed-off-by: Aaron Conole <aconole at redhat.com>
>> ---
>>  tests/system-traffic.at | 43 +++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 43 insertions(+)
>> 
>> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
>> index fb5b9a36d2..4971ccc966 100644
>> --- a/tests/system-traffic.at
>> +++ b/tests/system-traffic.at
>> @@ -5927,6 +5927,48 @@ ovs-appctl dpif/dump-flows br0
>>  OVS_TRAFFIC_VSWITCHD_STOP
>>  AT_CLEANUP
>>  
>> +
>> +AT_SETUP([conntrack - IPv4 UDP zero checksum])
>> +dnl This tracks sending zero checksum packets for udp over ipv4
>> +CHECK_CONNTRACK()
>> +OVS_TRAFFIC_VSWITCHD_START()
>> +OVS_CHECK_CT_CLEAR()
>> +
>> +ADD_NAMESPACES(at_ns0, at_ns1)
>> +ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24", "f0:00:00:01:01:01")
>> +ADD_VETH(p1, at_ns1, br0, "10.1.1.2/24", "f0:00:00:01:01:02")
>> +dnl setup ct flows
>> +AT_DATA([flows.txt], [dnl
>> +table=0,priority=10  ip,udp,ct_state=-trk action=ct(zone=1,table=1)
>> +table=0,priority=0   action=drop
>> +table=1,priority=10  ct_state=-est+trk+new,ip,ct_zone=1,in_port=1 action=ct(commit,table=2)
>> +table=1,priority=10  ct_state=+est-new+trk,ct_zone=1,in_port=1 action=resubmit(,2)
>> +table=1,priority=0   action=drop
>> +table=2,priority=10  ct_state=+trk+new,in_port=1 action=2
>> +table=2,priority=10  ct_state=+trk+est action=2
>> +])
>> +
>> +AT_CHECK([ovs-ofctl --bundle add-flows br0 flows.txt])
>> +
>> +# sending udp pkt
>> +NS_CHECK_EXEC([at_ns0], [$PYTHON3 $srcdir/sendpkt.py p0 f0 00 00 01
>> 01 02 f0 00 00 01 01 01 08 00 45 00 00 28 00 01 00 00 40 11 64 c0 0a
>> 01 01 01 0a 01 01 02 04 d2 04 d2 00 14 00 00 aa aa aa aa aa aa aa aa
>> aa aa aa aa > /dev/null])
>
> That hex string translates to this packet which doesn't use cksum:
> 12:57:40.065353 IP (tos 0x0, ttl 64, id 1, offset 0, flags [none],
> proto UDP (17), length 40)
>     10.1.1.1.search-agent > 10.1.1.2.search-agent: [no cksum] UDP,
> length 12

Yes, there should be no UDP checksum.  This is the point of this test.

>> +
>> +sleep 1
>
> Can we use OVS_WAIT_UNTIL() or OVS_WAIT_WHILE() ?

Good idea.

>> +
>> +dnl ensure CT picked up the packet
>> +AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1)], [0], [dnl
>> +udp,orig=(src=10.1.1.1,dst=10.1.1.2,sport=<cleared>,dport=<cleared>),reply=(src=10.1.1.2,dst=10.1.1.1,sport=<cleared>,dport=<cleared>)
>> +])
>> +
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep table=2, | OFPROTO_CLEAR_DURATION_IDLE],
>> +         [0], [dnl
>> + cookie=0x0, duration=<cleared>, table=2, n_packets=1, n_bytes=54,
>> idle_age=<cleared>, priority=10,ct_state=+new+trk,in_port=1
>> actions=output:2
>> + cookie=0x0, duration=<cleared>, table=2, n_packets=0, n_bytes=0,
>> idle_age=<cleared>, priority=10,ct_state=+est+trk actions=output:2
>> +])
>> +
>> +OVS_TRAFFIC_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>>  AT_SETUP([conntrack - Multiple ICMP traverse])
>>  dnl This tracks sending ICMP packets via conntrack multiple times for the
>>  dnl same packet
>> @@ -5971,6 +6013,7 @@ AT_CHECK([ovs-ofctl dump-flows br0 | grep table=2, | OFPROTO_CLEAR_DURATION_IDLE
>>  OVS_TRAFFIC_VSWITCHD_STOP
>>  AT_CLEANUP
>>  
>> +
>
> There mixed styles. Some use two lines, some use single line
> and some use two lines with a dnl ----- or ^L.
>
> I guess we should stick to single line, but I don't have a
> strong preference.

Oops, this snuck in.  I will remove it, and we can do something there
with a different patch if someone thinks it is needed.

> Otherwise the patch works for me.
>
> Thanks,
> fbl
>
>>  AT_BANNER([802.1ad])
>>  
>>  AT_SETUP([802.1ad - vlan_limit])
>> -- 
>> 2.25.4
>> 
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