Re: [PATCH v2 2/3] rndis_host: enable the bogus MAC fixup for ZTE devices from cdc_ether

[Lech Perczak <lech.perczak@xxxxxxxxx>]

W dniu 2022-04-13 o 02:11, Lech Perczak pisze:
> Certain ZTE modems, namely: MF823. MF831, MF910, built-in modem from
> MF286R, expose both CDC-ECM and RNDIS network interfaces.
> They have a trait of ignoring the locally-administered MAC address
> configured on the interface both in CDC-ECM and RNDIS part,
> and this leads to dropping of incoming traffic by the host.
> However, the workaround was only present in CDC-ECM, and MF286R
> explicitly requires it in RNDIS mode.
>
> Re-use the workaround in rndis_host as well, to fix operation of MF286R
> module, some versions of which expose only the RNDIS interface. Do so by
> introducing new flag, RNDIS_DRIVER_DATA_BOGUS_MAC, and testing for it in
And I just noticed that I forgot to rename that flag here, as well as
one unneded whitespace change creeped in. Will resend V3 shortly.
> rndis_rx_fixup. This is required, as RNDIS uses frame batching, and all
> of the packets inside the batch need the fixup. This might introduce a
> performance penalty, because test is done for every returned Ethernet
> frame.
>
> Apply the workaround to both "flavors" of RNDIS interfaces, as older ZTE
> modems, like MF823 found in the wild, report the USB_CLASS_COMM class
> interfaces, while MF286R reports USB_CLASS_WIRELESS_CONTROLLER.
>
> Suggested-by: Bjørn Mork <bjorn@xxxxxxx>
> Cc: Kristian Evensen <kristian.evensen@xxxxxxxxx>
> Cc: Oliver Neukum <oliver@xxxxxxxxxx>
> Signed-off-by: Lech Perczak <lech.perczak@xxxxxxxxx>
> ---
> v2:
> - Ensured that MAC fixup is applied to all Ethernet frames inside an
>    RNDIS batch. Thanks to Bjørn for finding the issue.
> - Introduced new driver flag to facilitate the above.
>
>   drivers/net/usb/rndis_host.c   | 33 ++++++++++++++++++++++++++++++++-
>   include/linux/usb/rndis_host.h |  1 +
>   2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c
> index 247f58cb0f84..18b27a4ed8bd 100644
> --- a/drivers/net/usb/rndis_host.c
> +++ b/drivers/net/usb/rndis_host.c
> @@ -485,10 +485,14 @@ EXPORT_SYMBOL_GPL(rndis_unbind);
>    */
>   int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
>   {
> +	bool dst_mac_fixup;
> +
>   	/* This check is no longer done by usbnet */
>   	if (skb->len < dev->net->hard_header_len)
>   		return 0;
>   
> +	dst_mac_fixup = !!(dev->driver_info->data & RNDIS_DRIVER_DATA_DST_MAC_FIXUP);
> +
>   	/* peripheral may have batched packets to us... */
>   	while (likely(skb->len)) {
>   		struct rndis_data_hdr	*hdr = (void *)skb->data;
> @@ -523,10 +527,17 @@ int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
>   			break;
>   		skb_pull(skb, msg_len - sizeof *hdr);
>   		skb_trim(skb2, data_len);
> +
> +		if (unlikely(dst_mac_fixup))
> +			usbnet_cdc_zte_rx_fixup(dev, skb2);
> +
>   		usbnet_skb_return(dev, skb2);
>   	}
>   
>   	/* caller will usbnet_skb_return the remaining packet */
> +	if (unlikely(dst_mac_fixup))
> +		usbnet_cdc_zte_rx_fixup(dev, skb);
> +
>   	return 1;
>   }
>   EXPORT_SYMBOL_GPL(rndis_rx_fixup);
> @@ -578,7 +589,6 @@ rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
>   }
>   EXPORT_SYMBOL_GPL(rndis_tx_fixup);
>   
> -
>   static const struct driver_info	rndis_info = {
>   	.description =	"RNDIS device",
>   	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
> @@ -600,6 +610,17 @@ static const struct driver_info	rndis_poll_status_info = {
>   	.tx_fixup =	rndis_tx_fixup,
>   };
>   
> +static const struct driver_info	zte_rndis_info = {
> +	.description =	"ZTE RNDIS device",
> +	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
> +	.data =		RNDIS_DRIVER_DATA_DST_MAC_FIXUP,
> +	.bind =		rndis_bind,
> +	.unbind =	rndis_unbind,
> +	.status =	rndis_status,
> +	.rx_fixup =	rndis_rx_fixup,
> +	.tx_fixup =	rndis_tx_fixup,
> +};
> +
>   /*-------------------------------------------------------------------------*/
>   
>   static const struct usb_device_id	products [] = {
> @@ -613,6 +634,16 @@ static const struct usb_device_id	products [] = {
>   	USB_VENDOR_AND_INTERFACE_INFO(0x238b,
>   				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
>   	.driver_info = (unsigned long)&rndis_info,
> +}, {
> +	/* ZTE WWAN modules */
> +	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
> +				      USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
> +	.driver_info = (unsigned long)&zte_rndis_info,
> +}, {
> +	/* ZTE WWAN modules, ACM flavour */
> +	USB_VENDOR_AND_INTERFACE_INFO(0x19d2,
> +				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
> +	.driver_info = (unsigned long)&zte_rndis_info,
>   }, {
>   	/* RNDIS is MSFT's un-official variant of CDC ACM */
>   	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
> diff --git a/include/linux/usb/rndis_host.h b/include/linux/usb/rndis_host.h
> index 809bccd08455..cc42db51bbba 100644
> --- a/include/linux/usb/rndis_host.h
> +++ b/include/linux/usb/rndis_host.h
> @@ -197,6 +197,7 @@ struct rndis_keepalive_c {	/* IN (optionally OUT) */
>   
>   /* Flags for driver_info::data */
>   #define RNDIS_DRIVER_DATA_POLL_STATUS	1	/* poll status before control */
> +#define RNDIS_DRIVER_DATA_DST_MAC_FIXUP	2	/* device ignores configured MAC address */
>   
>   extern void rndis_status(struct usbnet *dev, struct urb *urb);
>   extern int


--
Pozdrawiam/Kind regards,
Lech Perczak