cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

usbdevfs-drop-permissions.c (2385B)

      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}