db3476aff1
This commit puts all libio vtables in a dedicated, read-only ELF section, so that they are consecutive in memory. Before any indirect jump, the vtable pointer is checked against the section boundaries, and the process is terminated if the vtable pointer does not fall into the special ELF section. To enable backwards compatibility, a special flag variable (_IO_accept_foreign_vtables), protected by the pointer guard, avoids process termination if libio stream object constructor functions have been called earlier. Such constructor functions are called by the GCC 2.95 libstdc++ library, and this mechanism ensures compatibility with old binaries. Existing callers inside glibc of these functions are adjusted to call the original functions, not the wrappers which enable vtable compatiblity. The compatibility mechanism is used to enable passing FILE * objects across a static dlopen boundary, too.
125 lines
4.4 KiB
C
125 lines
4.4 KiB
C
/* Copyright (C) 1994-2016 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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As a special exception, if you link the code in this file with
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files compiled with a GNU compiler to produce an executable,
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that does not cause the resulting executable to be covered by
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the GNU Lesser General Public License. This exception does not
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however invalidate any other reasons why the executable file
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might be covered by the GNU Lesser General Public License.
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This exception applies to code released by its copyright holders
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in files containing the exception. */
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#include "libioP.h"
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#include "strfile.h"
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static wint_t _IO_wstrn_overflow (_IO_FILE *fp, wint_t c) __THROW;
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static wint_t
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_IO_wstrn_overflow (_IO_FILE *fp, wint_t c)
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{
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/* When we come to here this means the user supplied buffer is
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filled. But since we must return the number of characters which
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would have been written in total we must provide a buffer for
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further use. We can do this by writing on and on in the overflow
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buffer in the _IO_wstrnfile structure. */
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_IO_wstrnfile *snf = (_IO_wstrnfile *) fp;
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if (fp->_wide_data->_IO_buf_base != snf->overflow_buf)
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{
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_IO_wsetb (fp, snf->overflow_buf,
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snf->overflow_buf + (sizeof (snf->overflow_buf)
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/ sizeof (wchar_t)), 0);
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fp->_wide_data->_IO_write_base = snf->overflow_buf;
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fp->_wide_data->_IO_read_base = snf->overflow_buf;
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fp->_wide_data->_IO_read_ptr = snf->overflow_buf;
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fp->_wide_data->_IO_read_end = (snf->overflow_buf
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+ (sizeof (snf->overflow_buf)
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/ sizeof (wchar_t)));
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}
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fp->_wide_data->_IO_write_ptr = snf->overflow_buf;
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fp->_wide_data->_IO_write_end = snf->overflow_buf;
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/* Since we are not really interested in storing the characters
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which do not fit in the buffer we simply ignore it. */
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return c;
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}
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const struct _IO_jump_t _IO_wstrn_jumps libio_vtable attribute_hidden =
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{
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JUMP_INIT_DUMMY,
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JUMP_INIT(finish, _IO_wstr_finish),
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JUMP_INIT(overflow, (_IO_overflow_t) _IO_wstrn_overflow),
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JUMP_INIT(underflow, (_IO_underflow_t) _IO_wstr_underflow),
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JUMP_INIT(uflow, (_IO_underflow_t) _IO_wdefault_uflow),
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JUMP_INIT(pbackfail, (_IO_pbackfail_t) _IO_wstr_pbackfail),
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JUMP_INIT(xsputn, _IO_wdefault_xsputn),
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JUMP_INIT(xsgetn, _IO_wdefault_xsgetn),
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JUMP_INIT(seekoff, _IO_wstr_seekoff),
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JUMP_INIT(seekpos, _IO_default_seekpos),
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JUMP_INIT(setbuf, _IO_default_setbuf),
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JUMP_INIT(sync, _IO_default_sync),
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JUMP_INIT(doallocate, _IO_wdefault_doallocate),
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JUMP_INIT(read, _IO_default_read),
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JUMP_INIT(write, _IO_default_write),
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JUMP_INIT(seek, _IO_default_seek),
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JUMP_INIT(close, _IO_default_close),
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JUMP_INIT(stat, _IO_default_stat),
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JUMP_INIT(showmanyc, _IO_default_showmanyc),
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JUMP_INIT(imbue, _IO_default_imbue)
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};
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int
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_IO_vswprintf (wchar_t *string, _IO_size_t maxlen, const wchar_t *format,
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_IO_va_list args)
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{
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_IO_wstrnfile sf;
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int ret;
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struct _IO_wide_data wd;
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#ifdef _IO_MTSAFE_IO
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sf.f._sbf._f._lock = NULL;
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#endif
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if (maxlen == 0)
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/* Since we have to write at least the terminating L'\0' a buffer
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length of zero always makes the function fail. */
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return -1;
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_IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, 0, &wd, &_IO_wstrn_jumps);
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_IO_fwide (&sf.f._sbf._f, 1);
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string[0] = L'\0';
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_IO_wstr_init_static (&sf.f._sbf._f, string, maxlen - 1, string);
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ret = _IO_vfwprintf ((_IO_FILE *) &sf.f._sbf, format, args);
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if (sf.f._sbf._f._wide_data->_IO_buf_base == sf.overflow_buf)
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/* ISO C99 requires swprintf/vswprintf to return an error if the
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output does not fit in the provided buffer. */
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return -1;
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/* Terminate the string. */
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*sf.f._sbf._f._wide_data->_IO_write_ptr = '\0';
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return ret;
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}
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weak_alias (_IO_vswprintf, __vswprintf)
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ldbl_weak_alias (_IO_vswprintf, vswprintf)
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