Hi Bjørn, El 22/01/16 a las 06:41, Bjørn Mork escribió:
Emilio López <[email protected]> writes:diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 38ae877c..bf40aa6 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -77,6 +77,8 @@ struct usb_dev_state { unsigned long ifclaimed; u32 secid; u32 disabled_bulk_eps; + bool privileges_dropped; + unsigned long interface_allowed_mask; }; struct async { @@ -641,6 +643,14 @@ static int claimintf(struct usb_dev_state *ps, unsigned int ifnum) if (test_bit(ifnum, &ps->ifclaimed)) return 0; + if (ps->privileges_dropped) { + if (ifnum >= 8*sizeof(ps->interface_allowed_mask)) + return -EINVAL;I don't think you need this runtime test. You can just make sure that sizeof(ps->interface_allowed_mask) == sizeof(ps->ifclaimed) at build time. I do find this variable and arbitrary limit a bit confusing, but that's not your fault - I guess it is an indication that ifnums > 31 are rare :)diff --git a/include/uapi/linux/usbdevice_fs.h b/include/uapi/linux/usbdevice_fs.h index 019ba1e..9abcb34 100644 --- a/include/uapi/linux/usbdevice_fs.h +++ b/include/uapi/linux/usbdevice_fs.h @@ -154,6 +154,10 @@ struct usbdevfs_streams { unsigned char eps[0]; }; +struct usbdevfs_drop_privs { + unsigned long interface_allowed_mask; +}; +"unsigned long" isn't a very good choice here, is it?
I went with a type matching ifclaimed on struct usb_dev_state to keep the limit the same, but I guess it's not the best idea for an ioctl. I can switch it to __u32, keeping the runtime check above as is, or use __u64. Which one would you prefer?
Thanks for the review! Emilio
