On 2012.05.02 16:11, Pete Batard wrote: > Thanks for the info. > > On 2012.05.02 06:03, Xiaofan Chen wrote: >> Q5: When using interface control requests (LIBUSB_RECIPIENT_INTERFACE), >> WinUSB overrides the low byte of wIndex with the destination interface. >> Ref: http://www.lvr.com/forum/index.php?topic=331 >> >> A5: this is so you only target your interface on a composite device. >> Letting a >> user mode stack manipulate a sibling interface is bad security and >> encapsulation, no? > > Interesting. > > I could have sworn I saw some documentation indicating that > bmRequestType was supposed to be set to 0xC1 (=> recipient = interface) > when attempting to retrieve the Extended Properties OS Feature > Descriptor from a device. As a matter of fact, this is the info I > currently provide on the WCID page [1]. However, checking on the latest > MS documentation [2], it seems that Microsoft do state that it should be > set to 0xC0 (=> recipient = device), in which case the WinUSB override > does not occur.
Just to clarify the above, and how it relates to Q5, the retrieval of the Extended Properties OS Feature Descriptor requires setting wIndex to 0x05, which results in an override if using an interface request with WinUSB. /Pete ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ libusbx-devel mailing list libusbx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libusbx-devel
