1 /*
2 * Copyright (c) 2021 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29 #if (DEVELOPMENT || DEBUG) && !KASAN
30
31 #include <sys/sysctl.h>
32 #include <libkern/stack_protector.h>
33
34 __attribute__((noinline))
35 static int
check_for_cookie(size_t len)36 check_for_cookie(size_t len)
37 {
38 long buf[4];
39 long *search = (long *)(void *)&buf[0];
40 size_t n;
41
42 assert(len < sizeof(buf));
43 assert(__stack_chk_guard != 0);
44 assert(((uintptr_t)search & (sizeof(long) - 1)) == 0);
45
46 /* force compiler to insert stack cookie check: */
47 memset_s(buf, len, 0, len);
48
49 /* 32 x sizeof(long) should be plenty to find the cookie: */
50 for (n = 0; n < 32; ++n) {
51 if (*(search++) == __stack_chk_guard) {
52 return 0;
53 }
54 }
55
56 return ESRCH;
57 }
58
59 static int
60 sysctl_run_stack_chk_tests SYSCTL_HANDLER_ARGS
61 {
62 #pragma unused(arg1, arg2, oidp)
63
64 unsigned int dummy = 0;
65 int error, changed = 0, kr;
66 error = sysctl_io_number(req, 0, sizeof(dummy), &dummy, &changed);
67 if (error || !changed) {
68 return error;
69 }
70
71 kr = check_for_cookie(3);
72 return kr;
73 }
74
75 SYSCTL_PROC(_kern, OID_AUTO, run_stack_chk_tests,
76 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED | CTLFLAG_MASKED,
77 0, 0, sysctl_run_stack_chk_tests, "I", "");
78
79 #endif /* (DEVELOPMENT || DEBUG) && !KASAN */
80