1/*
2 * Copyright (c) 2014-2015 Dmitry V. Levin <ldv@altlinux.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 *    derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifdef HAVE_CONFIG_H
29# include "config.h"
30#endif
31#include <assert.h>
32#include <stdlib.h>
33#include <unistd.h>
34#include <fcntl.h>
35#include <sys/syscall.h>
36
37int
38main(void)
39{
40#if (defined __NR_getuid || defined __NR_getxuid) \
41 && defined(__NR_setuid) \
42 && defined(__NR_getresuid) \
43 && defined(__NR_setreuid) \
44 && defined(__NR_setresuid) \
45 && defined(__NR_fchown) \
46 && defined(__NR_getgroups)
47	int uid;
48	int size;
49	int *list = 0;
50
51#ifndef __NR_getuid
52# define __NR_getuid __NR_getxuid
53#endif
54	uid = syscall(__NR_getuid);
55
56	(void) close(0);
57	if (open("/proc/sys/kernel/overflowuid", O_RDONLY) == 0) {
58		/* we trust the kernel */
59		char buf[sizeof(int)*3];
60		int n = read(0, buf, sizeof(buf) - 1);
61		if (n) {
62			buf[n] = '\0';
63			n = atoi(buf);
64			if (uid == n)
65				return 77;
66		}
67		(void) close(0);
68	}
69
70	assert(syscall(__NR_setuid, uid) == 0);
71	{
72		/*
73		 * uids returned by getresuid should be ignored
74		 * to avoid 16bit vs 32bit issues.
75		 */
76		int r, e, s;
77		assert(syscall(__NR_getresuid, &r, &e, &s) == 0);
78	}
79	assert(syscall(__NR_setreuid, -1, -1L) == 0);
80	assert(syscall(__NR_setresuid, uid, -1, -1L) == 0);
81	assert(syscall(__NR_fchown, 1, -1, -1L) == 0);
82	assert((size = syscall(__NR_getgroups, 0, list)) >= 0);
83	assert(list = calloc(size + 1, sizeof(*list)));
84	assert(syscall(__NR_getgroups, size, list) == size);
85	return 0;
86#else
87	return 77;
88#endif
89}
90