1 | /* |
2 | * Copyright (c) 2016 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 | #include <string.h> |
30 | #include <sys/errno.h> |
31 | #include <stdint.h> |
32 | |
33 | extern void *secure_memset(void *, int, size_t); |
34 | |
35 | /* |
36 | * The memset_s function copies the value c into the first n bytes |
37 | * pointed by s. No more than smax bytes will be copied. |
38 | * |
39 | * In contrast to the memset function, calls to memset_s will never |
40 | * be ''optimised away'' by a compiler, ensuring the memory copy |
41 | * even if s is not accessed anymore after this call. |
42 | */ |
43 | int |
44 | memset_s(void *s, size_t smax, int c, size_t n) |
45 | { |
46 | int err = 0; |
47 | |
48 | if (s == NULL) { |
49 | return EINVAL; |
50 | } |
51 | if (smax > RSIZE_MAX) { |
52 | return E2BIG; |
53 | } |
54 | if (n > smax) { |
55 | n = smax; |
56 | err = EOVERFLOW; |
57 | } |
58 | |
59 | /* |
60 | * secure_memset is defined in assembly, we therefore |
61 | * expect that the compiler will not inline the call. |
62 | */ |
63 | secure_memset(s, c, n); |
64 | |
65 | return err; |
66 | } |
67 | |
68 | int |
69 | timingsafe_bcmp(const void *b1, const void *b2, size_t n) |
70 | { |
71 | const unsigned char *p1 = b1, *p2 = b2; |
72 | unsigned char ret = 0; |
73 | |
74 | for (; n > 0; n--) { |
75 | ret |= *p1++ ^ *p2++; |
76 | } |
77 | |
78 | /* map zero to zero and nonzero to one */ |
79 | return (ret + 0xff) >> 8; |
80 | } |
81 | |