Re: Extending USB_CONNECTINFO ioctl

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Jun 03, 2019 at 05:24:10PM -0700, Dmitry Torokhov wrote:
> Hi Alan, Greg,
> 
> When running software in a jailed environment where sysfs or udev is not
> readily available and one can only have an FD to usbdevfs device passed
> into the jail, there is a desire to allow libusb working. Alan recently
> added USBDEVFS_GET_SPEED, but we are still missing bus number and list
> of port numbers on the way to the root to be able to better identify the
> device in question.
> 
> What do you think about adding a new ioctl:
> 
> struct usbdevfs_connectinfo_ex {
> 	__u32 size;		/* size of the structure from the kernel POV */
> 	__u32 busnum;
> 	__u32 devnum;
> 	__u32 speed;		/* USB_SPEED_* form ch9.h */
> 	u8 num_ports;		/* Number of entries in port_numbers array */
> 	u8 port_numbers[31];	/* Current limit in USB3.0 spec is 7 */
> };
> 
> /*
>  * Returns struct usbdevfs_connectinfo_ex; length is variable to allow
>  * extending size of the data returned.
>  */
> #define USBDEVFS_CONNINFO_EX(len)  _IOC(_IOC_READ, 'U', 32, len)

Sounds reasonable, as long as you get the 'variable data' portion
correct :)

thanks,

greg k-h