diff mbox series

net: usb: usbnet: restore usb%d name exception for local mac addresses

Message ID 20241203130457.904325-1-asmadeus@codewreck.org (mailing list archive)
State New
Headers show
Series net: usb: usbnet: restore usb%d name exception for local mac addresses | expand

Commit Message

Dominique Martinet Dec. 3, 2024, 1:04 p.m. UTC 
From: Dominique Martinet <dominique.martinet@atmark-techno.com>

The previous commit 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.

Fixes: 8a7d12d674ac ("net: usb: usbnet: fix name regression")
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
---
 drivers/net/usb/usbnet.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

Comments

Greg KH Dec. 3, 2024, 2:48 p.m. UTC | #1 
On Tue, Dec 03, 2024 at 10:04:55PM +0900, Dominique Martinet wrote:
> From: Dominique Martinet <dominique.martinet@atmark-techno.com>
> 
> The previous commit 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.
> 
> Fixes: 8a7d12d674ac ("net: usb: usbnet: fix name regression")
> Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
> ---
>  drivers/net/usb/usbnet.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> index 44179f4e807f..d044dc7b7622 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;
> @@ -1762,13 +1773,10 @@ 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)
> -- 
> 2.47.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot
Andrew Lunn Dec. 3, 2024, 8:47 p.m. UTC | #2 
On Tue, Dec 03, 2024 at 10:04:55PM +0900, Dominique Martinet wrote:
> From: Dominique Martinet <dominique.martinet@atmark-techno.com>
> 
> The previous commit 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.

Are you saying the OTP or NVMEM has a locally administered MAC address
stored in it? Is there a mechanism to change it? The point about
locally administered MAC addresses is that they are locally
administered.

	Andrew
Jakub Kicinski Dec. 4, 2024, 2:13 a.m. UTC | #3 
On Tue, 3 Dec 2024 21:47:57 +0100 Andrew Lunn wrote:
> Are you saying the OTP or NVMEM has a locally administered MAC address
> stored in it? Is there a mechanism to change it? The point about
> locally administered MAC addresses is that they are locally
> administered.

You may also enjoy reading this :)

commit bfe9b9d2df669a57a95d641ed46eb018e204c6ce
Author: Kristian Evensen <kristian.evensen@gmail.com>
Date:   Thu Jul 21 11:10:06 2016 +0200

    cdc_ether: Improve ZTE MF823/831/910 handling
    
    The firmware in several ZTE devices (at least the MF823/831/910
    modems/mifis) use OS fingerprinting to determine which type of device to
    export. In addition, these devices export a REST API which can be used to
    control the type of device. So far, on Linux, the devices have been seen as
    RNDIS or CDC Ether.
    
    When CDC Ether is used, devices of the same type are, as with RNDIS,
    exported with the same, bogus random MAC address. In addition, the devices
    (at least on all firmware revisions I have found) use the bogus MAC when
    sending traffic routed from external networks. And as a final feature, the
    devices sometimes export the link state incorrectly. There are also
    references online to several other ZTE devices displaying this behavior,
    with several different PIDs and MAC addresses.
diff mbox series

Patch

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 44179f4e807f..d044dc7b7622 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;
@@ -1762,13 +1773,10 @@  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)