Hello Alan,
El 04/02/16 a las 13:27, Alan Stern escribió:
On Thu, 4 Feb 2016, Emilio López wrote:
From: Reilly Grant <reillyg@xxxxxxxxxxxx>
The new USBDEVFS_DROP_PRIVILEGES ioctl allows a process to voluntarily
relinquish the ability to issue other ioctls that may interfere with
other processes and drivers that have claimed an interface on the
device.
Signed-off-by: Reilly Grant <reillyg@xxxxxxxxxxxx>
Signed-off-by: Emilio López <emilio.lopez@xxxxxxxxxxxxxxx>
---
Changes in v3:
- Switch ioctl to use a __u32 given the iface qty is capped at 32
- Reword comments as requested by Alan
- Allow callers to shrink the allowed interfaces mask
@@ -624,6 +626,10 @@ static int claimintf(struct usb_dev_state *ps, unsigned int ifnum)
if (test_bit(ifnum, &ps->ifclaimed))
return 0;
+ if (ps->privileges_dropped
+ && !test_bit(ifnum, &ps->interface_allowed_mask))
Continuation lines in this file are indented by 2 tab stops, not 1
space.
Ok, I'll change it.
@@ -1198,6 +1202,27 @@ static int proc_connectinfo(struct usb_dev_state *ps, void __user *arg)
static int proc_resetdevice(struct usb_dev_state *ps)
{
+ struct usb_host_config *actconfig = ps->dev->actconfig;
+ struct usb_interface *interface;
+ int i, number;
+
+ /* Don't allow a device reset if the process has dropped the
+ * privilege to do such things and any of the interfaces are
+ * currently claimed.
+ */
+ if (ps->privileges_dropped && actconfig) {
+ for (i = 0; i < actconfig->desc.bNumInterfaces; ++i) {
+ interface = actconfig->interface[i];
+ number = interface->cur_altsetting->desc.bInterfaceNumber;
+ if (usb_interface_claimed(interface)) {
The test should be:
if (usb_interface_claimed(interface) &&
!test_bit(number, &ps->ifclaimed)) {
We don't want to prevent people from resetting a device merely because
they have claimed an interface. Only if someone else has claimed one.
Sounds sensible, now changed as well.
+ dev_warn(&ps->dev->dev,
+ "usbfs: interface %d claimed by %s while '%s' resets device\n",
+ number, interface->dev.driver->name, current->comm);
+ return -EACCES;
+ }
+ }
+ }
+
return usb_reset_device(ps->dev);
}
Also, it wouldn't hurt to change proc_get_capabilities() and
include/uapi/linux/usbdevicefs.h to add a USBDEVFS_CAP_DROP_PRIVILEGES
bit.
Good idea, I've added a bit now. I'm writing some docs and polishing a
program to test this as Greg requested and I'll submit v4 then.
Thanks!
Emilio
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