sysfs/udev in CT newbie(ish) question

[iamGavinJ]

Hi,
While I've been fairly entrenched in Linux for a number of years, I haven't ever really had the need to dive deep into sysfs and udev... until now :/

I'm trying to write some udev rules to do some specific things (namely a RUN) with `veth` interfaces however inside a container, I'm seeing a fraction of the available attributes that I see in the PVE host. What I'm specifically looking for is the `ID_NET_DRIVER` attribute which is set on the PVE host pair of the `veth` but missing on the CT side. Alternatively the `DEVTYPE` attribute would be helpful though from looking at the `veth.c` driver, it appears that's never being set anyway.

# udevadm info /devices/virtual/net/veth100i0
P: /devices/virtual/net/veth100i0
L: 0
E: DEVPATH=/devices/virtual/net/veth100i0
E: INTERFACE=veth100i0
E: IFINDEX=26
E: SUBSYSTEM=net
E: USEC_INITIALIZED=***REMOVED***
E: ID_NET_DRIVER=veth
E: ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
E: ID_NET_NAME=veth100i0
E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/veth100i0
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

Even if I create a new test pair of `veth`s inside the container, both the primary and peer are missing the `ID_NET_DRIVER` attribute.

# ip l add test type veth peer name testpeer
# udevadm info /devices/virtual/net/test
P: /devices/virtual/net/test
M: test
U: net
I: 20
E: DEVPATH=/devices/virtual/net/test
E: SUBSYSTEM=net
E: INTERFACE=test
E: IFINDEX=20

This is a problem for me, because while i *could* parse the interface names for the `veth` prefix, this naming convention is not mandatory, so I could potentially miss some interfaces when enumerating.

I'm wondering firstly where the discrepancy is rooted:

• Is it because unprivileged containers are not allowed to see the full scope of sysfs, even when devices are created and/or visible in that namespace?
• Is it something to do with running Arch (amd64) in the container?

And is there any way to get around this?

Kernel == 6.1.15-1-pve #1 SMP PREEMPT_DYNAMIC PVE 6.1.15-1 (2023-03-08T08:53Z) x86_64 GNU/Linux

Many thanks.