From: Dominique Martinet dominique.martinet@atmark-techno.com

BugLink: https://bugs.launchpad.net/bugs/2111592

commit 8a7d12d674ac ("net: usb: usbnet: fix name regression") assumed that local addresses always came from the kernel, but some devices hand out local mac addresses so we ended up with point-to-point devices with a mac set by the driver, renaming to eth%d when they used to be named usb%d.

Userspace should not rely on device name, but for the sake of stability restore the local mac address check portion of the naming exception: point to point devices which either have no mac set by the driver or have a local mac handed out by the driver will keep the usb%d name.

(some USB LTE modems are known to hand out a stable mac from the locally administered range; that mac appears to be random (different for mulitple devices) and can be reset with device-specific commands, so while such devices would benefit from getting a OUI reserved, we have to deal with these and might as well preserve the existing behavior to avoid breaking fragile openwrt configurations and such on upgrade.)

Link: https://lkml.kernel.org/r/20241203130457.904325-1-asmadeus@codewreck.org Fixes: 8a7d12d674ac ("net: usb: usbnet: fix name regression") Cc: stable@vger.kernel.org Tested-by: Ahmed Naseef naseefkm@gmail.com Signed-off-by: Dominique Martinet dominique.martinet@atmark-techno.com Acked-by: Oliver Neukum oneukum@suse.com Link: https://patch.msgid.link/20250326-usbnet_rename-v2-1-57eb21fcff26@atmark-tec... Signed-off-by: Jakub Kicinski kuba@kernel.org

(cherry picked from commit 2ea396448f26d0d7d66224cb56500a6789c7ed07) Signed-off-by: Jianlin Lv iecedge@gmail.com --- drivers/net/usb/usbnet.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 9f66c47dc58b..08cbc8e4b361 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -178,6 +178,17 @@ int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress) } EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);

+static bool usbnet_needs_usb_name_format(struct usbnet *dev, struct net_device *net) +{ + /* Point to point devices which don't have a real MAC address + * (or report a fake local one) have historically used the usb%d + * naming. Preserve this.. + */ + return (dev->driver_info->flags & FLAG_POINTTOPOINT) != 0 && + (is_zero_ether_addr(net->dev_addr) || + is_local_ether_addr(net->dev_addr)); +} + static void intr_complete (struct urb *urb) { struct usbnet *dev = urb->context; @@ -1766,13 +1777,11 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) if (status < 0) goto out1;

- // heuristic: "usb%d" for links we know are two-host, - // else "eth%d" when there's reasonable doubt. userspace - // can rename the link if it knows better. + /* heuristic: rename to "eth%d" if we are not sure this link + * is two-host (these links keep "usb%d") + */ if ((dev->driver_info->flags & FLAG_ETHER) != 0 && - ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 || - /* somebody touched it*/ - !is_zero_ether_addr(net->dev_addr))) + !usbnet_needs_usb_name_format(dev, net)) strscpy(net->name, "eth%d", sizeof(net->name)); /* WLAN devices should always be named "wlan%d" */ if ((dev->driver_info->flags & FLAG_WLAN) != 0)