1 | /* Stack executability handling for GNU dynamic linker. Linux version. |
2 | Copyright (C) 2003-2017 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 | <http://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 <caller.h> |
26 | #include <sysdep.h> |
27 | |
28 | |
29 | extern int __stack_prot attribute_relro attribute_hidden; |
30 | |
31 | |
32 | int |
33 | internal_function |
34 | _dl_make_stack_executable (void **stack_endp) |
35 | { |
36 | /* This gives us the highest/lowest page that needs to be changed. */ |
37 | uintptr_t page = ((uintptr_t) *stack_endp |
38 | & -(intptr_t) GLRO(dl_pagesize)); |
39 | int result = 0; |
40 | |
41 | /* Challenge the caller. */ |
42 | if (__builtin_expect (__check_caller (RETURN_ADDRESS (0), |
43 | allow_ldso|allow_libpthread) != 0, 0) |
44 | || __builtin_expect (*stack_endp != __libc_stack_end, 0)) |
45 | return EPERM; |
46 | |
47 | if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize), |
48 | __stack_prot) == 0, 1)) |
49 | goto return_success; |
50 | result = errno; |
51 | goto out; |
52 | |
53 | return_success: |
54 | /* Clear the address. */ |
55 | *stack_endp = NULL; |
56 | |
57 | /* Remember that we changed the permission. */ |
58 | GL(dl_stack_flags) |= PF_X; |
59 | |
60 | out: |
61 | #ifdef check_consistency |
62 | check_consistency (); |
63 | #endif |
64 | |
65 | return result; |
66 | } |
67 | rtld_hidden_def (_dl_make_stack_executable) |
68 | |