1/* Stack executability handling for GNU dynamic linker. Linux version.
2 Copyright (C) 2003-2020 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 <ldsodefs.h>
20#include <sys/mman.h>
21#include <errno.h>
22#include <libintl.h>
23#include <stdbool.h>
24#include <stackinfo.h>
25#include <sysdep.h>
26
27
28extern int __stack_prot attribute_relro attribute_hidden;
29
30
31int
32_dl_make_stack_executable (void **stack_endp)
33{
34 /* This gives us the highest/lowest page that needs to be changed. */
35 uintptr_t page = ((uintptr_t) *stack_endp
36 & -(intptr_t) GLRO(dl_pagesize));
37 int result = 0;
38
39 if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize),
40 __stack_prot) == 0, 1))
41 goto return_success;
42 result = errno;
43 goto out;
44
45 return_success:
46 /* Clear the address. */
47 *stack_endp = NULL;
48
49 /* Remember that we changed the permission. */
50 GL(dl_stack_flags) |= PF_X;
51
52 out:
53#ifdef check_consistency
54 check_consistency ();
55#endif
56
57 return result;
58}
59rtld_hidden_def (_dl_make_stack_executable)
60