[PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[Peter Korsgaard]

The OS descriptors logic had the high/low byte of w_value inverted, causing
the extended properties to not be accessible for interface != 0.

From the Microsoft documentation:
https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-os-1-0-descriptors-specification

OS_Desc_CompatID.doc (w_index = 0x4):

- wValue:

  High Byte = InterfaceNumber.  InterfaceNumber is set to the number of the
  interface or function that is associated with the descriptor, typically
  0x00.  Because a device can have only one extended compat ID descriptor,
  it should ignore InterfaceNumber, regardless of the value, and simply
  return the descriptor.

  Low Byte = 0.  PageNumber is used to retrieve descriptors that are larger
  than 64 KB.  The header section is 16 bytes, so PageNumber is set to 0 for
  this request.

We currently do not support >64KB compat ID descriptors, so verify that the
low byte is 0.

OS_Desc_Ext_Prop.doc (w_index = 0x5):

- wValue:

  High byte = InterfaceNumber.  The high byte of wValue is set to the number
  of the interface or function that is associated with the descriptor.

  Low byte = PageNumber.  The low byte of wValue is used to retrieve
  descriptors that are larger than 64 KB.  The header section is 10 bytes, so
  PageNumber is set to 0 for this request.

We also don't support >64KB extended properties, so verify that the low byte
is 0 and use the high byte for the interface number.

Fixes: 37a3a533429e ("usb: gadget: OS Feature Descriptors support")

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
 drivers/usb/gadget/composite.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 0ace45b66a31..0e151b54aae8 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -2112,7 +2112,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 			buf[5] = 0x01;
 			switch (ctrl->bRequestType & USB_RECIP_MASK) {
 			case USB_RECIP_DEVICE:
-				if (w_index != 0x4 || (w_value >> 8))
+				if (w_index != 0x4 || (w_value & 0xff))
 					break;
 				buf[6] = w_index;
 				/* Number of ext compat interfaces */
@@ -2128,9 +2128,9 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 				}
 				break;
 			case USB_RECIP_INTERFACE:
-				if (w_index != 0x5 || (w_value >> 8))
+				if (w_index != 0x5 || (w_value & 0xff))
 					break;
-				interface = w_value & 0xFF;
+				interface = w_value >> 8;
 				if (interface >= MAX_CONFIG_INTERFACES ||
 				    !os_desc_cfg->interface[interface])
 					break;
-- 
2.39.2

Re: [PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[Andrzej Pietrasiewicz]

Hi Peter,

W dniu 4.04.2024 o 12:06, Peter Korsgaard pisze:
> The OS descriptors logic had the high/low byte of w_value inverted, causing
> the extended properties to not be accessible for interface != 0.

Out of curiosity - did you run into problems running some USB gadget,
and if yes, what was it? Or is this patch a result of a code and documentation
review without actually running a gadget?

> 
>  From the Microsoft documentation:
> https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-os-1-0-descriptors-specification
> 
> OS_Desc_CompatID.doc (w_index = 0x4):
> 
> - wValue:
> 
>    High Byte = InterfaceNumber.  InterfaceNumber is set to the number of the
>    interface or function that is associated with the descriptor, typically
>    0x00.  Because a device can have only one extended compat ID descriptor,
>    it should ignore InterfaceNumber, regardless of the value, and simply
>    return the descriptor.
> 
>    Low Byte = 0.  PageNumber is used to retrieve descriptors that are larger
>    than 64 KB.  The header section is 16 bytes, so PageNumber is set to 0 for
>    this request.
> 
> We currently do not support >64KB compat ID descriptors, so verify that the
> low byte is 0.
> 
> OS_Desc_Ext_Prop.doc (w_index = 0x5):
> 
> - wValue:
> 
>    High byte = InterfaceNumber.  The high byte of wValue is set to the number
>    of the interface or function that is associated with the descriptor.
> 
>    Low byte = PageNumber.  The low byte of wValue is used to retrieve
>    descriptors that are larger than 64 KB.  The header section is 10 bytes, so
>    PageNumber is set to 0 for this request.
> 

FWIW w_value is:

u16 w_value = le16_to_cpu(ctrl->wValue);

Regards,

Andrzej


> We also don't support >64KB extended properties, so verify that the low byte
> is 0 and use the high byte for the interface number.
> 
> Fixes: 37a3a533429e ("usb: gadget: OS Feature Descriptors support")
> 
> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
> ---
>   drivers/usb/gadget/composite.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 0ace45b66a31..0e151b54aae8 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -2112,7 +2112,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
>   			buf[5] = 0x01;
>   			switch (ctrl->bRequestType & USB_RECIP_MASK) {
>   			case USB_RECIP_DEVICE:
> -				if (w_index != 0x4 || (w_value >> 8))
> +				if (w_index != 0x4 || (w_value & 0xff))
>   					break;
>   				buf[6] = w_index;
>   				/* Number of ext compat interfaces */
> @@ -2128,9 +2128,9 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
>   				}
>   				break;
>   			case USB_RECIP_INTERFACE:
> -				if (w_index != 0x5 || (w_value >> 8))
> +				if (w_index != 0x5 || (w_value & 0xff))
>   					break;
> -				interface = w_value & 0xFF;
> +				interface = w_value >> 8;
>   				if (interface >= MAX_CONFIG_INTERFACES ||
>   				    !os_desc_cfg->interface[interface])
>   					break;

Re: [PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[Peter Korsgaard]

>>>>> "Andrzej" == Andrzej Pietrasiewicz <andrzej.p@collabora.com> writes:

 > Hi Peter,
 > W dniu 4.04.2024 o 12:06, Peter Korsgaard pisze:
 >> The OS descriptors logic had the high/low byte of w_value inverted, causing
 >> the extended properties to not be accessible for interface != 0.

 > Out of curiosity - did you run into problems running some USB gadget,
 > and if yes, what was it? Or is this patch a result of a code and documentation
 > review without actually running a gadget?

I had issues with getting Windows to accept the OS descriptors when the
function I wanted to use with WinUSB was not the first (= interface 0)
function in a composite device together with HID and mass storage.

-- 
Bye, Peter Korsgaard

[PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[Vrastil, Michal]

From 118f8c8b72d633c0daa65e564e48cbf4964977ab Mon Sep 17 00:00:00 2001
From: Michal Vrastil <michal.vrastil@hidglobal.com>
Date: Tue, 3 Sep 2024 10:55:15 +0200
Subject: [PATCH] Revert "usb: gadget: composite: fix OS descriptors w_value
logic"

This reverts commit ec6ce7075ef879b91a8710829016005dc8170f17.

Fix install of WinUSB dsriver using OS descriptors. Without the fix the drivers are not installed correctly
and the property 'DeviceInterfaceGUID' is missing on host side.

The original change was based on assumption that the interface number is in the high byte of wValue but it is in the low byte, instead.
Unfortunately, the fix is based on MS documentation which is also wrong.

The actual USB request for OS descriptors (using USB analyzer) looks like:

Offset  0   1   2   3   4   5   6   7
0x000   C1  A1  02  00  05  00  0A  00

C1: bmRequestType (device to host, vendor, interface)
A1: nas magic number
0002: wValue (2: nas interface)
0005: wIndex (5: get extended property i.e. nas interface GUID)
008E: wLength (142)

The fix was tested on Windows 10 and Windows 11.

Signed-off-by: Michal Vrastil <michal.vrastil@hidglobal.com>
---
drivers/usb/gadget/composite.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 17ae3b394469..a3106b179562 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1925,7 +1925,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
                                               buf[5] = 0x01;
                                               switch (ctrl->bRequestType & USB_RECIP_MASK) {
                                               case USB_RECIP_DEVICE:
-                                                              if (w_index != 0x4 || (w_value & 0xff))
+                                                             if (w_index != 0x4 || (w_value >> 8))
                                                                               break;
                                                               buf[6] = w_index;
                                                               /* Number of ext compat interfaces */
@@ -1941,9 +1941,9 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
                                                               }
                                                               break;
                                               case USB_RECIP_INTERFACE:
-                                                              if (w_index != 0x5 || (w_value & 0xff))
+                                                             if (w_index != 0x5 || (w_value >> 8))
                                                                               break;
-                                                              interface = w_value >> 8;
+                                                             interface = w_value & 0xFF;
                                                               if (interface >= MAX_CONFIG_INTERFACES ||
                                                                   !os_desc_cfg->interface[interface])
                                                                               break;
-- 
2.43.0

Re: [PATCH] usb: gadget: composite: fix OS descriptors w_value logic

[Greg KH]

On Tue, Sep 03, 2024 at 11:14:39AM +0000, Vrastil, Michal wrote:
> >From 118f8c8b72d633c0daa65e564e48cbf4964977ab Mon Sep 17 00:00:00 2001
> From: Michal Vrastil <michal.vrastil@hidglobal.com>
> Date: Tue, 3 Sep 2024 10:55:15 +0200
> Subject: [PATCH] Revert "usb: gadget: composite: fix OS descriptors w_value
> logic"

This looks odd, did you mean to put the whole commit in the mail?

Also, all tabs are gone, meaning you probably did a cut/paste thing,
please read the kernel documentation for how to use 'git send-email' to
make this simpler?

> 
> This reverts commit ec6ce7075ef879b91a8710829016005dc8170f17.
> 
> Fix install of WinUSB dsriver using OS descriptors. Without the fix the drivers are not installed correctly
> and the property 'DeviceInterfaceGUID' is missing on host side.
> 
> The original change was based on assumption that the interface number is in the high byte of wValue but it is in the low byte, instead.
> Unfortunately, the fix is based on MS documentation which is also wrong.

Please wrap your changelog text at 72 columns like your editor tried to
get you to do :)
> 
> The actual USB request for OS descriptors (using USB analyzer) looks like:
> 
> Offset  0   1   2   3   4   5   6   7
> 0x000   C1  A1  02  00  05  00  0A  00
> 
> C1: bmRequestType (device to host, vendor, interface)
> A1: nas magic number
> 0002: wValue (2: nas interface)
> 0005: wIndex (5: get extended property i.e. nas interface GUID)
> 008E: wLength (142)
> 
> The fix was tested on Windows 10 and Windows 11.
> 
> Signed-off-by: Michal Vrastil <michal.vrastil@hidglobal.com>

What commit id does this fix?

thanks,

greg k-h