1#include <sys/ioctl.h>
  2#include <sys/types.h>
  3#include <sys/stat.h>
  4#include <fcntl.h>
  5#include <stdio.h>
  6#include <errno.h>
  7#include <string.h>
  8#include <inttypes.h>
  9#include <unistd.h>
 10
 11#include <linux/usbdevice_fs.h>
 12
 13/* For building without an updated set of headers */
 14#ifndef USBDEVFS_DROP_PRIVILEGES
 15#define USBDEVFS_DROP_PRIVILEGES		_IOW('U', 30, __u32)
 16#define USBDEVFS_CAP_DROP_PRIVILEGES		0x40
 17#endif
 18
 19void drop_privileges(int fd, uint32_t mask)
 20{
 21	int res;
 22
 23	res = ioctl(fd, USBDEVFS_DROP_PRIVILEGES, &mask);
 24	if (res)
 25		printf("ERROR: USBDEVFS_DROP_PRIVILEGES returned %d\n", res);
 26	else
 27		printf("OK: privileges dropped!\n");
 28}
 29
 30void reset_device(int fd)
 31{
 32	int res;
 33
 34	res = ioctl(fd, USBDEVFS_RESET);
 35	if (!res)
 36		printf("OK: USBDEVFS_RESET succeeded\n");
 37	else
 38		printf("ERROR: reset failed! (%d - %s)\n",
 39		       -res, strerror(-res));
 40}
 41
 42void claim_some_intf(int fd)
 43{
 44	int i, res;
 45
 46	for (i = 0; i < 4; i++) {
 47		res = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &i);
 48		if (!res)
 49			printf("OK: claimed if %d\n", i);
 50		else
 51			printf("ERROR claiming if %d (%d - %s)\n",
 52			       i, -res, strerror(-res));
 53	}
 54}
 55
 56int main(int argc, char *argv[])
 57{
 58	uint32_t mask, caps;
 59	int c, fd;
 60
 61	fd = open(argv[1], O_RDWR);
 62	if (fd < 0) {
 63		printf("Failed to open file\n");
 64		goto err_fd;
 65	}
 66
 67	/*
 68	 * check if dropping privileges is supported,
 69	 * bail on systems where the capability is not present
 70	 */
 71	ioctl(fd, USBDEVFS_GET_CAPABILITIES, &caps);
 72	if (!(caps & USBDEVFS_CAP_DROP_PRIVILEGES)) {
 73		printf("DROP_PRIVILEGES not supported\n");
 74		goto err;
 75	}
 76
 77	/*
 78	 * Drop privileges but keep the ability to claim all
 79	 * free interfaces (i.e., those not used by kernel drivers)
 80	 */
 81	drop_privileges(fd, -1U);
 82
 83	printf("Available options:\n"
 84		"[0] Exit now\n"
 85		"[1] Reset device. Should fail if device is in use\n"
 86		"[2] Claim 4 interfaces. Should succeed where not in use\n"
 87		"[3] Narrow interface permission mask\n"
 88		"Which option shall I run?: ");
 89
 90	while (scanf("%d", &c) == 1) {
 91		switch (c) {
 92		case 0:
 93			goto exit;
 94		case 1:
 95			reset_device(fd);
 96			break;
 97		case 2:
 98			claim_some_intf(fd);
 99			break;
100		case 3:
101			printf("Insert new mask: ");
102			scanf("%x", &mask);
103			drop_privileges(fd, mask);
104			break;
105		default:
106			printf("I don't recognize that\n");
107		}
108
109		printf("Which test shall I run next?: ");
110	}
111
112exit:
113	close(fd);
114	return 0;
115
116err:
117	close(fd);
118err_fd:
119	return 1;
120}

  1#include <sys/ioctl.h>
  2#include <sys/types.h>
  3#include <sys/stat.h>
  4#include <fcntl.h>
  5#include <stdio.h>
  6#include <errno.h>
  7#include <string.h>
  8#include <inttypes.h>
  9#include <unistd.h>
 10
 11#include <linux/usbdevice_fs.h>
 12
 13/* For building without an updated set of headers */
 14#ifndef USBDEVFS_DROP_PRIVILEGES
 15#define USBDEVFS_DROP_PRIVILEGES		_IOW('U', 30, __u32)
 16#define USBDEVFS_CAP_DROP_PRIVILEGES		0x40
 17#endif
 18
 19void drop_privileges(int fd, uint32_t mask)
 20{
 21	int res;
 22
 23	res = ioctl(fd, USBDEVFS_DROP_PRIVILEGES, &mask);
 24	if (res)
 25		printf("ERROR: USBDEVFS_DROP_PRIVILEGES returned %d\n", res);
 26	else
 27		printf("OK: privileges dropped!\n");
 28}
 29
 30void reset_device(int fd)
 31{
 32	int res;
 33
 34	res = ioctl(fd, USBDEVFS_RESET);
 35	if (!res)
 36		printf("OK: USBDEVFS_RESET succeeded\n");
 37	else
 38		printf("ERROR: reset failed! (%d - %s)\n",
 39		       -res, strerror(-res));
 40}
 41
 42void claim_some_intf(int fd)
 43{
 44	int i, res;
 45
 46	for (i = 0; i < 4; i++) {
 47		res = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &i);
 48		if (!res)
 49			printf("OK: claimed if %d\n", i);
 50		else
 51			printf("ERROR claiming if %d (%d - %s)\n",
 52			       i, -res, strerror(-res));
 53	}
 54}
 55
 56int main(int argc, char *argv[])
 57{
 58	uint32_t mask, caps;
 59	int c, fd;
 60
 61	fd = open(argv[1], O_RDWR);
 62	if (fd < 0) {
 63		printf("Failed to open file\n");
 64		goto err_fd;
 65	}
 66
 67	/*
 68	 * check if dropping privileges is supported,
 69	 * bail on systems where the capability is not present
 70	 */
 71	ioctl(fd, USBDEVFS_GET_CAPABILITIES, &caps);
 72	if (!(caps & USBDEVFS_CAP_DROP_PRIVILEGES)) {
 73		printf("DROP_PRIVILEGES not supported\n");
 74		goto err;
 75	}
 76
 77	/*
 78	 * Drop privileges but keep the ability to claim all
 79	 * free interfaces (i.e., those not used by kernel drivers)
 80	 */
 81	drop_privileges(fd, -1U);
 82
 83	printf("Available options:\n"
 84		"[0] Exit now\n"
 85		"[1] Reset device. Should fail if device is in use\n"
 86		"[2] Claim 4 interfaces. Should succeed where not in use\n"
 87		"[3] Narrow interface permission mask\n"
 88		"Which option shall I run?: ");
 89
 90	while (scanf("%d", &c) == 1) {
 91		switch (c) {
 92		case 0:
 93			goto exit;
 94		case 1:
 95			reset_device(fd);
 96			break;
 97		case 2:
 98			claim_some_intf(fd);
 99			break;
100		case 3:
101			printf("Insert new mask: ");
102			scanf("%x", &mask);
103			drop_privileges(fd, mask);
104			break;
105		default:
106			printf("I don't recognize that\n");
107		}
108
109		printf("Which test shall I run next?: ");
110	}
111
112exit:
113	close(fd);
114	return 0;
115
116err:
117	close(fd);
118err_fd:
119	return 1;
120}