Bug#934589: udev: net.ifnames is wrongly imported as a property for any/all devices

[quidame]

Hi,

On 12/08/2019 13:14, Michael Biebl wrote:
> Control: tags -1 + moreinfo unreproducible

To reproduce it, as said in the report, net.ifnames MUST BE SET in the
boot commandline.

$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-4.19.0-5-amd64 root=/dev/mapper/luks-root ro
net.ifnames=0 quiet

The bug is fully reproducible on fresh installs of debian stable (udev
241-5), testing (udev 241-7) and sid (udev 241-7).

> I don't use LVM, but running that e.g. on /dev/sda5, I get

LVM doesn't matter here, as the property is imported to ALL devices,
including /dev/null !!! (as said in the report)

> What do you get if you run
> grep ifnames /etc/udev/rules.d/* /lib/udev/rules.d/*

I already did this before reporting the bug, and pointed to the first
line of /lib/udev/rules.d/73-usb-net-by-mac.rules, that is shipped with
the udev package:

IMPORT{cmdline}="net.ifnames"

As said in udev(7):

IMPORT{type}
    Import a set of variables as device properties, depending on "type":
    [...]
    "cmdline"
        Import a single property from the kernel command line. For
        simple flags the value of the property is set to "1".


And again, for me the culprit is a missing block of filters **before**
this IMPORT directive,

> Can you tar up all files in /etc/udev/rules.d and /lib/udev/rules.d and
> attach it to this bug report.

My /etc/udev/rules.d is empty.
The only relevant file in /lib/udev/rules.d is 73-usb-net-by-mac.rules
(attached, unchanged)

Thanks,
quidame
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# Use MAC based names for network interfaces which are directly or indirectly
# on USB and have an universally administered (stable) MAC address (second bit
# is 0). Don't do this when ifnames is disabled via kernel command line or
# customizing/disabling 99-default.link (or previously 80-net-setup-link.rules).

IMPORT{cmdline}="net.ifnames"
ENV{net.ifnames}=="0", GOTO="usb_net_by_mac_end"

ACTION=="add", SUBSYSTEM=="net", SUBSYSTEMS=="usb", NAME=="", \
    ATTR{address}=="?[014589cd]:*", \
    TEST!="/etc/udev/rules.d/80-net-setup-link.rules", \
    TEST!="/etc/systemd/network/99-default.link", \
    IMPORT{builtin}="net_id", NAME="$env{ID_NET_NAME_MAC}"

LABEL="usb_net_by_mac_end"
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