Commit 2ea39644 authored by Dominique Martinet's avatar Dominique Martinet Committed by Jakub Kicinski
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net: usb: usbnet: restore usb%d name exception for local mac addresses 

commit 8a7d12d6 ("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: 8a7d12d6 ("net: usb: usbnet: fix name regression")
Cc: stable@vger.kernel.org
Tested-by: default avatarAhmed Naseef <naseefkm@gmail.com>
Signed-off-by: default avatarDominique Martinet <dominique.martinet@atmark-techno.com>
Acked-by: default avatarOliver Neukum <oneukum@suse.com>
Link: https://patch.msgid.link/20250326-usbnet_rename-v2-1-57eb21fcff26@atmark-techno.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent fab05835

drivers/net/usb/usbnet.c

+15 −6
Original line number Diff line number Diff line
@@ -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;
@@ -1762,13 +1773,11 @@ 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)