Description of problem:

When a system has a different naming for network interfaces between RHEL7 and RHEL8, persistentnetnamesconfig.py generates network ".link" files to make sure the RHEL7 naming is kept once upgraded.

The code bases itself on the MAC address of the network interface.
Unfortunately when having a bond, the MAC address for the 2nd slave is not computed correctly: it's the MAC address of the bond (hence 1st slave) that is returned instead of the Permanent MAC address (the MAC address of the physical card).
This generates a broken ".link" file which ends up having the network card be renamed by RHEL8 through using the standard scheme, as shown in the example below:

Interfaces on RHEL7 (all Mellanox cards, which get renamed):

• bond0, MAC 0c:42:a1:1c:b6:d6 with slaves
• eno1, MAC 0c:42:a1:1c:b6:d6
• enp59s0f0, MAC 0c:42:a1:24:95:96 but seen as "0c:42:a1:1c:b6:d6" because of the bond
• enp59s0f1, MAC 0c:42:a1:24:95:97

Files created by Leapp for network interfaces:

• /etc/systemd/network/10-leapp-eno1.link (OK)

[Match]
MACAddress=0c:42:a1:1c:b6:d6
[Link]
Name=eno1

• /etc/systemd/network/10-leapp-enp59s0f0.link (KO because slave of the bond)

[Match]
MACAddress=0c:42:a1:1c:b6:d6
[Link]
Name=enp59s0f0

• /etc/systemd/network/10-leapp-enp59s0f1.link (OK)

[Match]
MACAddress=0c:42:a1:24:95:97
[Link]
Name=enp59s0f1

Interfaces as seen on RHEL8:

• eno1 kept as is
• enp59s0f0 becomes ens1f0 because standard naming is used (/etc/systemd/network/10-leapp-enp59s0f0.link doesn't match because of the MAC address generated in the file)
• enp59s0f1 kept as is because of /etc/systemd/network/10-leapp-enp59s0f1.link

Digging further, it appears the following code is "faulty":

/usr/share/leapp-repository/repositories/system_upgrade/common/libraries/persistentnetnames.py:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
1 import pyudev
:
34 def interfaces():
35 """
36 Generator which produces an Interface objects containing assorted interface properties relevant for network na ming
37 """
38 for dev in physical_interfaces():
39 attrs = {}
40
41 try:
42 attrs['name'] = dev.sys_name
43 attrs['devpath'] = dev.device_path
44 attrs['driver'] = dev['ID_NET_DRIVER']
45 attrs['vendor'] = dev['ID_VENDOR_ID']
46 attrs['pci_info'] = PCIAddress(**pci_info(dev['ID_PATH']))
47 attrs['mac'] = dev.attributes.get('address')
:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

On line 47, the code relies on *address* attribute which is the NON-PERMANENT MAC when part of a bond.

Because udev has no knowledge of the Permanent Address, the only solution I found is to extract the MAC address from the ID_NET_NAME_MAC property instead, something like this patch below:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

1. diff -u /usr/share/leapp-repository/repositories/system_upgrade/common/libraries/persistentnetnames.py.orig /usr/share/leapp-repository/repositories/system_upgrade/common/libraries/persistentnetnames.py
   • • /usr/share/leapp-repository/repositories/system_upgrade/common/libraries/persistentnetnames.py.orig 2022-08-17 16:57:19.000000000 +0200
       +++ /usr/share/leapp-repository/repositories/system_upgrade/common/libraries/persistentnetnames.py 2022-09-01 16:57:58.635000000 +0200
       @@ -1,4 +1,5 @@
       import pyudev
       +import re

from leapp.libraries.stdlib import api
from leapp.models import Interface, PCIAddress
@@ -44,9 +45,11 @@
attrs['driver'] = dev['ID_NET_DRIVER']
attrs['vendor'] = dev['ID_VENDOR_ID']
attrs['pci_info'] = PCIAddress(**pci_info(dev['ID_PATH']))

• attrs['mac'] = dev.attributes.get('address')
• if isinstance(attrs['mac'], bytes):
• attrs['mac'] = attrs['mac'].decode()
  + assert dev['ID_NET_NAME_MAC'].startswith('enx')
  + attrs['mac'] = ':'.join(re.findall('..', dev['ID_NET_NAME_MAC'][3:]))
  + #attrs['mac'] = dev.attributes.get('address')
  + #if isinstance(attrs['mac'], bytes):
  + # attrs['mac'] = attrs['mac'].decode()
  except Exception as e: # pylint: disable=broad-except

1. FIXME(msekleta): We should probably handle errors more granularly
2. Maybe we should inhibit upgrade process at this point
   • • • • • • • 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

It's ugly/hacky but seems to work but probably DOESN'T cover all cases, specially non-ethernet network interfaces.
Maybe udev needs enhancement to store the permanent address somewhere.

Version-Release number of selected component (if applicable):

leapp-upgrade-el7toel8-0.16.0-8.el7_9.noarch

How reproducible:

Always

Steps to Reproduce:
1. Add 2 network interfaces in a VM and create a bond

enp7s0: 52:54:00:cf:e9:a8
enp8s0: 52:54:00:23:46:01

2. Execute "leapp pre-upgrade"
3. Check DB content (/var/lib/leapp/leapp.db)

Actual results: (same MACs for enp7s0 and enp8s0)

{"devpath": "/devices/pci0000:00/0000:00:02.6/0000:07:00.0/net/enp7s0", "driver": "e1000e", "mac": "52:54:00:cf:e9:a8", "name": "enp7s0", "pci_info":

{"bus": "07", "device": "00", "domain": "0000", "function": "0"}

, "vendor": "0x8086"},
{"devpath": "/devices/pci0000:00/0000:00:02.7/0000:08:00.0/net/enp8s0", "driver": "e1000e", "mac": "52:54:00:cf:e9:a8", "name": "enp8s0", "pci_info":

{"bus": "08", "device": "00", "domain": "0000", "function": "0"}

, "vendor": "0x8086"}

Expected results: (permanent MAC for enp8s0)

{"devpath": "/devices/pci0000:00/0000:00:02.6/0000:07:00.0/net/enp7s0", "driver": "e1000e", "mac": "52:54:00:cf:e9:a8", "name": "enp7s0", "pci_info":

{"bus": "07", "device": "00", "domain": "0000", "function": "0"}

, "vendor": "0x8086"},
{"devpath": "/devices/pci0000:00/0000:00:02.7/0000:08:00.0/net/enp8s0", "driver": "e1000e", "mac": "52:54:00:23:46:01", "name": "enp8s0", "pci_info":

{"bus": "08", "device": "00", "domain": "0000", "function": "0"}

, "vendor": "0x8086"}

Additional info:

I don't know if this applies to Leapp 8 -> 9