Re: [PATCH] enable usb control message with class specific request

[Matthias Dellweg]

Am Fri, 23 Sep 2011 14:31:40 -0400 (EDT)
schrieb Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:

> On Fri, 23 Sep 2011, Matthias Dellweg wrote:
> 
> > Am Fri, 23 Sep 2011 12:16:40 -0400 (EDT)
> > schrieb Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:
> > > This is basically okay.  But your mailer has mangled the
> > > whitespace. [...]
> > > Alan Stern
> > 
> > OK, hoping that my mailer doesn't get wild again, this is the
> > polished version following your suggestions.
> > Thanks for your help!
> >   Matthias Dellweg
> > 
> > From b7c4b6f5780296fd0d53d66e08d5bce0dc450b7f Mon Sep 17 00:00:00
> > 2001 From: Matthias Dellweg <2500@xxxxxx>
> > Date: Fri, 23 Sep 2011 19:32:39 +0200
> > Subject: [PATCH] drivers/usb/core/devio.c: Check for printer class
> > specific request
> > 
> > Signed-off-by: Matthias Dellweg <2500@xxxxxx>
> > ---
> >  drivers/usb/core/devio.c |   20 +++++++++++++++++---
> >  1 files changed, 17 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> > index 37518df..e4175cc 100644
> > --- a/drivers/usb/core/devio.c
> > +++ b/drivers/usb/core/devio.c
> > @@ -607,9 +607,10 @@ static int findintfep(struct usb_device *dev,
> > unsigned int ep) }
> >  
> >  static int check_ctrlrecip(struct dev_state *ps, unsigned int
> > requesttype,
> > -			   unsigned int index)
> > +			   unsigned int request, unsigned int
> > index) {
> >  	int ret = 0;
> > +	struct usb_host_interface *alt_setting;
> >  
> >  	if (ps->dev->state != USB_STATE_UNAUTHENTICATED
> >  	 && ps->dev->state != USB_STATE_ADDRESS
> > @@ -618,6 +619,18 @@ static int check_ctrlrecip(struct dev_state
> > *ps, unsigned int requesttype, if (USB_TYPE_VENDOR ==
> > (USB_TYPE_MASK & requesttype)) return 0;
> >  
> > +	/*
> > +	 * check for the special corner case 'get_device_id' in
> > the printer
> > +	 * class specification, where wIndex is (interface << 8 |
> > altsetting)
> > +	 */
> > +	if (requesttype == 0xa1 && request == 0) {
> > +		alt_setting =
> > usb_find_alt_setting(ps->dev->actconfig,
> > +						   index >> 8,
> > index & 0xff);
> > +		if (alt_setting
> > +		 && alt_setting->desc.bInterfaceClass ==
> > USB_CLASS_PRINTER)
> > +			index >>= 8;
> > +	}
> > +
> >  	index &= 0xff;
> >  	switch (requesttype & USB_RECIP_MASK) {
> >  	case USB_RECIP_ENDPOINT:
> > @@ -770,7 +783,8 @@ static int proc_control(struct dev_state *ps,
> > void __user *arg) 
> >  	if (copy_from_user(&ctrl, arg, sizeof(ctrl)))
> >  		return -EFAULT;
> > -	ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.wIndex);
> > +	ret = check_ctrlrecip(ps, ctrl.bRequestType, ctrl.bRequest,
> > +			      ctrl.wIndex);
> >  	if (ret)
> >  		return ret;
> >  	wLength = ctrl.wLength;		/* To suppress 64k
> > PAGE_SIZE warning */ @@ -1100,7 +1114,7 @@ static int
> > proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
> > kfree(dr); return -EINVAL;
> >  		}
> > -		ret = check_ctrlrecip(ps, dr->bRequestType,
> > +		ret = check_ctrlrecip(ps, dr->bRequestType,
> > dr->bRequest, le16_to_cpup(&dr->wIndex));
> >  		if (ret) {
> >  			kfree(dr);
> > 
> 
> This looks fine to me.  Greg may ask you for a non-empty patch
> description when you submit it to him.
> 
> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> 
> Alan Stern

Hi Greg,
I hear you are the right person to ask for including this patch.
The relevant section in the printer class spec is 4.2.1. I believe this
is a really special corner case, because I did not find another such
'violation' of the common usb spec on a quick search.
The hardware I tested this patch with is a Prolific 
USB->Centronics cable (067b:2305).
  Matthias Dellweg