From d883f52e1f6d2eca8378e3795f333c1396943873 Mon Sep 17 00:00:00 2001 From: Reilly Grant Date: Sun, 21 Feb 2016 18:38:01 -0300 Subject: usb: devio: Add ioctl to disallow detaching kernel USB drivers. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. This commit also includes a simple utility to be able to test the ioctl, located at Documentation/usb/usbdevfs-drop-permissions.c Example (with qemu-kvm's input device): $ lsusb ... Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd $ usb-devices ... C: #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=usbhid $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002 OK: privileges dropped! Available options: [0] Exit now [1] Reset device. Should fail if device is in use [2] Claim 4 interfaces. Should succeed where not in use [3] Narrow interface permission mask Which option shall I run?: 1 ERROR: USBDEVFS_RESET failed! (1 - Operation not permitted) Which test shall I run next?: 2 ERROR claiming if 0 (1 - Operation not permitted) ERROR claiming if 1 (1 - Operation not permitted) ERROR claiming if 2 (1 - Operation not permitted) ERROR claiming if 3 (1 - Operation not permitted) Which test shall I run next?: 0 After unbinding usbhid: $ usb-devices ... I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=(none) $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002 ... Which option shall I run?: 2 OK: claimed if 0 ERROR claiming if 1 (1 - Operation not permitted) ERROR claiming if 2 (1 - Operation not permitted) ERROR claiming if 3 (1 - Operation not permitted) Which test shall I run next?: 1 OK: USBDEVFS_RESET succeeded Which test shall I run next?: 0 After unbinding usbhid and restricting the mask: $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002 ... Which option shall I run?: 3 Insert new mask: 0 OK: privileges dropped! Which test shall I run next?: 2 ERROR claiming if 0 (1 - Operation not permitted) ERROR claiming if 1 (1 - Operation not permitted) ERROR claiming if 2 (1 - Operation not permitted) ERROR claiming if 3 (1 - Operation not permitted) Signed-off-by: Reilly Grant Acked-by: Alan Stern Signed-off-by: Emilio López Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/usbdevice_fs.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/uapi/linux/usbdevice_fs.h b/include/uapi/linux/usbdevice_fs.h index ecbd17650e6c..a8653a6f40df 100644 --- a/include/uapi/linux/usbdevice_fs.h +++ b/include/uapi/linux/usbdevice_fs.h @@ -135,6 +135,7 @@ struct usbdevfs_hub_portinfo { #define USBDEVFS_CAP_BULK_SCATTER_GATHER 0x08 #define USBDEVFS_CAP_REAP_AFTER_DISCONNECT 0x10 #define USBDEVFS_CAP_MMAP 0x20 +#define USBDEVFS_CAP_DROP_PRIVILEGES 0x40 /* USBDEVFS_DISCONNECT_CLAIM flags & struct */ @@ -188,5 +189,6 @@ struct usbdevfs_streams { #define USBDEVFS_DISCONNECT_CLAIM _IOR('U', 27, struct usbdevfs_disconnect_claim) #define USBDEVFS_ALLOC_STREAMS _IOR('U', 28, struct usbdevfs_streams) #define USBDEVFS_FREE_STREAMS _IOR('U', 29, struct usbdevfs_streams) +#define USBDEVFS_DROP_PRIVILEGES _IOW('U', 30, __u32) #endif /* _UAPI_LINUX_USBDEVICE_FS_H */ -- cgit v1.2.3