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db3476af | 1 | /* libio vtable validation. |
04277e02 | 2 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
db3476af FW |
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 <dlfcn.h> | |
20 | #include <libioP.h> | |
21 | #include <stdio.h> | |
8e1472d2 | 22 | #include <ldsodefs.h> |
db3476af FW |
23 | |
24 | #ifdef SHARED | |
25 | ||
26 | void (*IO_accept_foreign_vtables) (void) attribute_hidden; | |
27 | ||
28 | /* Used to detected multiple libcs. */ | |
29 | extern struct dl_open_hook *_dl_open_hook; | |
30 | libc_hidden_proto (_dl_open_hook); | |
31 | ||
32 | #else /* !SHARED */ | |
33 | ||
34 | /* Used to check whether static dlopen support is needed. */ | |
35 | # pragma weak __dlopen | |
36 | ||
37 | #endif | |
38 | ||
39 | void attribute_hidden | |
40 | _IO_vtable_check (void) | |
41 | { | |
42 | #ifdef SHARED | |
43 | /* Honor the compatibility flag. */ | |
44 | void (*flag) (void) = atomic_load_relaxed (&IO_accept_foreign_vtables); | |
92777f34 | 45 | #ifdef PTR_DEMANGLE |
db3476af | 46 | PTR_DEMANGLE (flag); |
92777f34 | 47 | #endif |
db3476af FW |
48 | if (flag == &_IO_vtable_check) |
49 | return; | |
50 | ||
51 | /* In case this libc copy is in a non-default namespace, we always | |
52 | need to accept foreign vtables because there is always a | |
53 | possibility that FILE * objects are passed across the linking | |
54 | boundary. */ | |
55 | { | |
56 | Dl_info di; | |
57 | struct link_map *l; | |
8e1472d2 | 58 | if (!rtld_active () |
db3476af FW |
59 | || (_dl_addr (_IO_vtable_check, &di, &l, NULL) != 0 |
60 | && l->l_ns != LM_ID_BASE)) | |
61 | return; | |
62 | } | |
63 | ||
64 | #else /* !SHARED */ | |
65 | /* We cannot perform vtable validation in the static dlopen case | |
66 | because FILE * handles might be passed back and forth across the | |
67 | boundary. Therefore, we disable checking in this case. */ | |
68 | if (__dlopen != NULL) | |
69 | return; | |
70 | #endif | |
71 | ||
72 | __libc_fatal ("Fatal error: glibc detected an invalid stdio handle\n"); | |
73 | } | |
c402355d FW |
74 | |
75 | /* Some variants of libstdc++ interpose _IO_2_1_stdin_ etc. and | |
76 | install their own vtables directly, without calling _IO_init or | |
77 | other functions. Detect this by looking at the vtables values | |
78 | during startup, and disable vtable validation in this case. */ | |
79 | #ifdef SHARED | |
80 | __attribute__ ((constructor)) | |
81 | static void | |
82 | check_stdfiles_vtables (void) | |
83 | { | |
84 | if (_IO_2_1_stdin_.vtable != &_IO_file_jumps | |
85 | || _IO_2_1_stdout_.vtable != &_IO_file_jumps | |
86 | || _IO_2_1_stderr_.vtable != &_IO_file_jumps) | |
87 | IO_set_accept_foreign_vtables (&_IO_vtable_check); | |
88 | } | |
89 | #endif |