File: dl-execstack.c

package info (click to toggle)
glibc 2.24-10
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 223,412 kB
  • sloc: ansic: 991,967; asm: 261,800; sh: 10,385; makefile: 9,710; cpp: 4,169; python: 3,971; perl: 2,254; awk: 1,753; pascal: 1,521; yacc: 291; sed: 80
file content (67 lines) | stat: -rw-r--r-- 1,987 bytes parent folder | download | duplicates (5)
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
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
/* Stack executability handling for GNU dynamic linker.  Linux version.
   Copyright (C) 2003-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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
   <http://www.gnu.org/licenses/>.  */

#include <ldsodefs.h>
#include <sys/mman.h>
#include <errno.h>
#include <libintl.h>
#include <stdbool.h>
#include <stackinfo.h>
#include <caller.h>
#include <sysdep.h>


extern int __stack_prot attribute_relro attribute_hidden;


int
internal_function
_dl_make_stack_executable (void **stack_endp)
{
  /* This gives us the highest/lowest page that needs to be changed.  */
  uintptr_t page = ((uintptr_t) *stack_endp
		    & -(intptr_t) GLRO(dl_pagesize));
  int result = 0;

  /* Challenge the caller.  */
  if (__builtin_expect (__check_caller (RETURN_ADDRESS (0),
					allow_ldso|allow_libpthread) != 0, 0)
      || __builtin_expect (*stack_endp != __libc_stack_end, 0))
    return EPERM;

  if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize),
				    __stack_prot) == 0, 1))
    goto return_success;
  result = errno;
  goto out;

 return_success:
  /* Clear the address.  */
  *stack_endp = NULL;

  /* Remember that we changed the permission.  */
  GL(dl_stack_flags) |= PF_X;

 out:
#ifdef check_consistency
  check_consistency ();
#endif

  return result;
}
rtld_hidden_def (_dl_make_stack_executable)