mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 12:11:40 +00:00
d883f52e1f
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 <reillyg@chromium.org> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
121 lines
2.3 KiB
C
121 lines
2.3 KiB
C
#include <sys/ioctl.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <inttypes.h>
|
|
#include <unistd.h>
|
|
|
|
#include <linux/usbdevice_fs.h>
|
|
|
|
/* For building without an updated set of headers */
|
|
#ifndef USBDEVFS_DROP_PRIVILEGES
|
|
#define USBDEVFS_DROP_PRIVILEGES _IOW('U', 30, __u32)
|
|
#define USBDEVFS_CAP_DROP_PRIVILEGES 0x40
|
|
#endif
|
|
|
|
void drop_privileges(int fd, uint32_t mask)
|
|
{
|
|
int res;
|
|
|
|
res = ioctl(fd, USBDEVFS_DROP_PRIVILEGES, &mask);
|
|
if (res)
|
|
printf("ERROR: USBDEVFS_DROP_PRIVILEGES returned %d\n", res);
|
|
else
|
|
printf("OK: privileges dropped!\n");
|
|
}
|
|
|
|
void reset_device(int fd)
|
|
{
|
|
int res;
|
|
|
|
res = ioctl(fd, USBDEVFS_RESET);
|
|
if (!res)
|
|
printf("OK: USBDEVFS_RESET succeeded\n");
|
|
else
|
|
printf("ERROR: reset failed! (%d - %s)\n",
|
|
-res, strerror(-res));
|
|
}
|
|
|
|
void claim_some_intf(int fd)
|
|
{
|
|
int i, res;
|
|
|
|
for (i = 0; i < 4; i++) {
|
|
res = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &i);
|
|
if (!res)
|
|
printf("OK: claimed if %d\n", i);
|
|
else
|
|
printf("ERROR claiming if %d (%d - %s)\n",
|
|
i, -res, strerror(-res));
|
|
}
|
|
}
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
uint32_t mask, caps;
|
|
int c, fd;
|
|
|
|
fd = open(argv[1], O_RDWR);
|
|
if (fd < 0) {
|
|
printf("Failed to open file\n");
|
|
goto err_fd;
|
|
}
|
|
|
|
/*
|
|
* check if dropping privileges is supported,
|
|
* bail on systems where the capability is not present
|
|
*/
|
|
ioctl(fd, USBDEVFS_GET_CAPABILITIES, &caps);
|
|
if (!(caps & USBDEVFS_CAP_DROP_PRIVILEGES)) {
|
|
printf("DROP_PRIVILEGES not supported\n");
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* Drop privileges but keep the ability to claim all
|
|
* free interfaces (i.e., those not used by kernel drivers)
|
|
*/
|
|
drop_privileges(fd, -1U);
|
|
|
|
printf("Available options:\n"
|
|
"[0] Exit now\n"
|
|
"[1] Reset device. Should fail if device is in use\n"
|
|
"[2] Claim 4 interfaces. Should succeed where not in use\n"
|
|
"[3] Narrow interface permission mask\n"
|
|
"Which option shall I run?: ");
|
|
|
|
while (scanf("%d", &c) == 1) {
|
|
switch (c) {
|
|
case 0:
|
|
goto exit;
|
|
case 1:
|
|
reset_device(fd);
|
|
break;
|
|
case 2:
|
|
claim_some_intf(fd);
|
|
break;
|
|
case 3:
|
|
printf("Insert new mask: ");
|
|
scanf("%x", &mask);
|
|
drop_privileges(fd, mask);
|
|
break;
|
|
default:
|
|
printf("I don't recognize that\n");
|
|
}
|
|
|
|
printf("Which test shall I run next?: ");
|
|
}
|
|
|
|
exit:
|
|
close(fd);
|
|
return 0;
|
|
|
|
err:
|
|
close(fd);
|
|
err_fd:
|
|
return 1;
|
|
}
|