vxlan from net/rtnetlink.sh in ubuntu_kernel_selftests failed on B-5.4

[Po-Hsu Lin]

Issue found on 5.4.0-1030.32~18.04.1-gke
with instance f1.micro and others

 # PASS: set ifalias 13cda380-4dc6-4596-83e6-b03fee5025ce for test-dummy0
 # PASS: vrf
 # FAIL: vxlan
 # PASS: fou
 # PASS: macsec
 # PASS: ipsec

This can be found in 5.4.0-1026.26~18.04.1-gke as well, not a regression.

Maybe it's not supported? I can see vxlan4 related test skipped in net/pmtu.sh test because it's not supported.

This will need to be investigated.

[Kleber Sacilotto de Souza (kleber-souza)]

Issue found with bionic/linux-hwe-5.4 5.4.0-79.88~18.04.1.

[Kleber Sacilotto de Souza (kleber-souza)]

I came up with a smaller version of the vxlan exerciser from rtnetlink.sh:

==================================================
$ cat test_vxlan.sh
#!/bin/bash
set -x

# setup
ip link add name test-dummy0 type dummy
ip link set test-dummy0 up
ip netns add testns
ip -netns testns link set lo up
ip -netns testns link add name test-dummy0 type dummy
ip -netns testns link set test-dummy0 up
ip -netns testns link add test-vxlan0 type vxlan id 42 group 239.1.1.1 dev test-dummy0 dstport 4789

# This is expected to fail
ip -netns testns link set dev test-vxlan0 type vxlan ttl inherit
echo $?

# cleanup
ip -netns testns link del test-vxlan0
ip netns del testns
ip link del dev test-dummy0
==================================================

With the same 5.4 kernel, on Focal the line which is flagged as expected to fail returns:

+ ip -netns testns link set dev test-vxlan0 type vxlan ttl inherit
Error: vxlan: cannot change TTL_INHERIT flag.
+ echo 2
2

while on Bionic it succeeds.

[Po-Hsu Lin (cypressyew)]

Note: this test would require CONFIG_VXLAN.

The following line is failing on B-ibm-5.4:
$ # changelink testcases
$ sudo ip -netns "$testns" link set dev "$vxlan" type vxlan vni 43
Error: Cannot change VNI.