1 /*
2 * Copyright (C) 2012 The Android Open Source Project
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 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #undef _FORTIFY_SOURCE
30
31 #include <string.h>
32 #include <stdlib.h>
33 #include "private/libc_logging.h"
34
35 /*
36 * Runtime implementation of __builtin____strncpy_chk.
37 *
38 * See
39 * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
40 * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
41 * for details.
42 *
43 * This strncpy check is called if _FORTIFY_SOURCE is defined and
44 * greater than 0.
45 */
__strncpy_chk(char * __restrict dest,const char * __restrict src,size_t len,size_t dest_len)46 extern "C" char* __strncpy_chk(char* __restrict dest, const char* __restrict src,
47 size_t len, size_t dest_len) {
48 if (__predict_false(len > dest_len)) {
49 __fortify_chk_fail("strncpy: prevented write past end of buffer",
50 BIONIC_EVENT_STRNCPY_BUFFER_OVERFLOW);
51 }
52
53 return strncpy(dest, src, len);
54 }
55
56 /*
57 * __strncpy_chk2
58 *
59 * This is a variant of __strncpy_chk, but it also checks to make
60 * sure we don't read beyond the end of "src". The code for this is
61 * based on the original version of strncpy, but modified to check
62 * how much we read from "src" at the end of the copy operation.
63 */
__strncpy_chk2(char * __restrict dst,const char * __restrict src,size_t n,size_t dest_len,size_t src_len)64 extern "C" char* __strncpy_chk2(char* __restrict dst, const char* __restrict src,
65 size_t n, size_t dest_len, size_t src_len)
66 {
67 if (__predict_false(n > dest_len)) {
68 __fortify_chk_fail("strncpy: prevented write past end of buffer",
69 BIONIC_EVENT_STRNCPY_BUFFER_OVERFLOW);
70 }
71 if (n != 0) {
72 char* d = dst;
73 const char* s = src;
74
75 do {
76 if ((*d++ = *s++) == 0) {
77 /* NUL pad the remaining n-1 bytes */
78 while (--n != 0) {
79 *d++ = 0;
80 }
81 break;
82 }
83 } while (--n != 0);
84
85 size_t s_copy_len = static_cast<size_t>(s - src);
86 if (__predict_false(s_copy_len > src_len)) {
87 __fortify_chk_fail("strncpy: prevented read past end of buffer", 0);
88 }
89 }
90
91 return dst;
92 }
93