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Use fortify macros for b{zero,copy} along decl from strings.h

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As described in BZ#20558, bzero and bcopy declaration can only benefit
from fortified macros when decl came from string.h and when __USE_MISC
is defined (default behaviour).

This is due no standard includes those functions in string.h, so they
are only declared if __USE_MISC is defined (as pointed out in comment 4).
However fortification should be orthogona to other features test macros,
i.e, any function should be fortified if that function is declared.

To fix this behavior, the patch moved the bzero, bcopy, and
__explicit_bzero_chk to a common header (string/bits/strings_fortified.h)
and explicit fortified inclusion macros similar to string.h is added
on strings.h.  This allows to get fortified declarions by only including
strings.h.

Checked on x86_64-linux-gnu and along on a bootstrap installation to check
if the fortified are correctly triggered with example from bug report.

	[BZ #20558]
	* string/bits/string3.h [__USE_MISC] (bcopy): Move to
	strings_fortified.h.
	[__USE_MISC] (bzero): Likewise.
	[__USE_MISC] (explicit_bzero): Likewise.
	* string/strings.h: Include strings_fortified.h.
	* string/Makefile (headers): Add strings_fortified.h.
	* string/bits/strings_fortified.h: New file.
	* include/bits/strings_fortified.h: Likewise.
This commit is contained in:
Adhemerval Zanella 2017-01-05 10:07:24 -02:00
parent 983a9637f7
commit 38765ab68f
6 changed files with 67 additions and 21 deletions
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12
ChangeLog
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@ -1,3 +1,15 @@
2017-01-05 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #20558]
* string/bits/string3.h [__USE_MISC] (bcopy): Move to
strings_fortified.h.
[__USE_MISC] (bzero): Likewise.
[__USE_MISC] (explicit_bzero): Likewise.
* string/strings.h: Include strings_fortified.h.
* string/Makefile (headers): Add strings_fortified.h.
* string/bits/strings_fortified.h: New file.
* include/bits/strings_fortified.h: Likewise.
2017-01-05 Joseph Myers <joseph@codesourcery.com>
* elf/tst-tls13.c (TIMEOUT): Remove.

1
include/bits/strings_fortified.h Normal file
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@ -0,0 +1 @@
#include <string/bits/strings_fortified.h>

3
string/Makefile
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@ -24,7 +24,8 @@ include ../Makeconfig
headers := string.h strings.h memory.h endian.h bits/endian.h \
argz.h envz.h byteswap.h bits/byteswap.h bits/byteswap-16.h \
bits/string.h bits/string2.h bits/string3.h
bits/string.h bits/string2.h bits/string3.h \
bits/strings_fortified.h
routines := strcat strchr strcmp strcoll strcpy strcspn \
strverscmp strdup strndup \

21
string/bits/string3.h
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@ -91,26 +91,7 @@ __NTH (memset (void *__dest, int __ch, size_t __len))
}
#ifdef __USE_MISC
__fortify_function void
__NTH (bcopy (const void *__src, void *__dest, size_t __len))
{
(void) __builtin___memmove_chk (__dest, __src, __len, __bos0 (__dest));
}
__fortify_function void
__NTH (bzero (void *__dest, size_t __len))
{
(void) __builtin___memset_chk (__dest, '\0', __len, __bos0 (__dest));
}
void __explicit_bzero_chk (void *__dest, size_t __len, size_t __destlen)
__THROW __nonnull ((1));
__fortify_function void
__NTH (explicit_bzero (void *__dest, size_t __len))
{
__explicit_bzero_chk (__dest, __len, __bos0 (__dest));
}
# include <bits/strings_fortified.h>
#endif
__fortify_function char *

43
string/bits/strings_fortified.h Normal file
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@ -0,0 +1,43 @@
/* Fortify macros for strings.h functions.
Copyright (C) 2017 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/>. */
#ifndef __STRINGS_FORTIFIED
# define __STRINGS_FORTIFIED 1
__fortify_function void
__NTH (bcopy (const void *__src, void *__dest, size_t __len))
{
(void) __builtin___memmove_chk (__dest, __src, __len, __bos0 (__dest));
}
__fortify_function void
__NTH (bzero (void *__dest, size_t __len))
{
(void) __builtin___memset_chk (__dest, '\0', __len, __bos0 (__dest));
}
void __explicit_bzero_chk (void *__dest, size_t __len, size_t __destlen)
__THROW __nonnull ((1));
__fortify_function void
__NTH (explicit_bzero (void *__dest, size_t __len))
{
__explicit_bzero_chk (__dest, __len, __bos0 (__dest));
}
#endif

8
string/strings.h
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@ -136,4 +136,12 @@ __END_DECLS
#endif /* string.h */
#if __GNUC_PREREQ (3,4) && __USE_FORTIFY_LEVEL > 0 \
&& defined __fortify_function
/* Functions with security checks. */
# if defined __USE_MISC || !defined __USE_XOPEN2K8
# include <bits/strings_fortified.h>
# endif
#endif
#endif /* strings.h */