1/* Operating system specific code for generic dynamic loader functions. Linux.
2 Copyright (C) 2000-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <dl-sysdep.h>
20#include <endian.h>
21#include <fcntl.h>
22#include <stdint.h>
23#include <not-cancel.h>
24
25static inline uintptr_t __attribute__ ((always_inline))
26_dl_setup_stack_chk_guard (void *dl_random)
27{
28 union
29 {
30 uintptr_t num;
31 unsigned char bytes[sizeof (uintptr_t)];
32 } ret;
33
34 /* We need in the moment only 8 bytes on 32-bit platforms and 16
35 bytes on 64-bit platforms. Therefore we can use the data
36 directly and not use the kernel-provided data to seed a PRNG. */
37 memcpy (ret.bytes, dl_random, sizeof (ret));
38#if BYTE_ORDER == LITTLE_ENDIAN
39 ret.num &= ~(uintptr_t) 0xff;
40#elif BYTE_ORDER == BIG_ENDIAN
41 ret.num &= ~((uintptr_t) 0xff << (8 * (sizeof (ret) - 1)));
42#else
43# error "BYTE_ORDER unknown"
44#endif
45 return ret.num;
46}
47
48static inline uintptr_t __attribute__ ((always_inline))
49_dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)
50{
51 uintptr_t ret;
52 memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));
53 return ret;
54}
55