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89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
/* libio vtable validation.
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <dlfcn.h>
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#include <libioP.h>
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#include <stdio.h>
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#ifdef SHARED
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void (*IO_accept_foreign_vtables) (void) attribute_hidden;
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/* Used to detected multiple libcs. */
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extern struct dl_open_hook *_dl_open_hook;
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libc_hidden_proto (_dl_open_hook);
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#else /* !SHARED */
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/* Used to check whether static dlopen support is needed. */
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# pragma weak __dlopen
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#endif
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void attribute_hidden
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_IO_vtable_check (void)
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{
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#ifdef SHARED
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/* Honor the compatibility flag. */
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void (*flag) (void) = atomic_load_relaxed (&IO_accept_foreign_vtables);
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (flag);
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#endif
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if (flag == &_IO_vtable_check)
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return;
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/* In case this libc copy is in a non-default namespace, we always
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need to accept foreign vtables because there is always a
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possibility that FILE * objects are passed across the linking
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boundary. */
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{
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Dl_info di;
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struct link_map *l;
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if (_dl_open_hook != NULL
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|| (_dl_addr (_IO_vtable_check, &di, &l, NULL) != 0
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&& l->l_ns != LM_ID_BASE))
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return;
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}
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#else /* !SHARED */
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/* We cannot perform vtable validation in the static dlopen case
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because FILE * handles might be passed back and forth across the
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boundary. Therefore, we disable checking in this case. */
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if (__dlopen != NULL)
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return;
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#endif
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__libc_fatal ("Fatal error: glibc detected an invalid stdio handle\n");
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}
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/* Some variants of libstdc++ interpose _IO_2_1_stdin_ etc. and
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install their own vtables directly, without calling _IO_init or
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other functions. Detect this by looking at the vtables values
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during startup, and disable vtable validation in this case. */
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#ifdef SHARED
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__attribute__ ((constructor))
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static void
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check_stdfiles_vtables (void)
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{
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if (_IO_2_1_stdin_.vtable != &_IO_file_jumps
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|| _IO_2_1_stdout_.vtable != &_IO_file_jumps
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|| _IO_2_1_stderr_.vtable != &_IO_file_jumps)
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IO_set_accept_foreign_vtables (&_IO_vtable_check);
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}
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#endif
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