1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
/* PLT rewrite helper function. Linux/x86-64 version.
Copyright (C) 2024 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdbool.h>
#include <sys/mman.h>
static __always_inline bool
dl_plt_rewrite_supported (void)
{
/* PLT rewrite is enabled. Check if mprotect works. */
void *plt = (void *) INTERNAL_SYSCALL_CALL (mmap, NULL, 4096,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
if (__glibc_unlikely (plt == MAP_FAILED))
return false;
/* Touch the PROT_READ | PROT_WRITE page. */
*(int32_t *) plt = 1;
/* If the updated PROT_READ | PROT_WRITE page can be changed to
PROT_EXEC | PROT_READ, rewrite PLT. */
bool status = (INTERNAL_SYSCALL_CALL (mprotect, plt, 4096,
PROT_EXEC | PROT_READ) == 0);
INTERNAL_SYSCALL_CALL (munmap, plt, 4096);
return status;
}
|
