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tunables: Use direct syscall for access (BZ#21744)

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The function maybe_enable_malloc_check, which is called by
__tunables_init, calls __access_noerrno.  It isn't problem when
symbol is is in ld.so, which has a special version of __access_noerrno
without stack protector.  But when glibc is built with stack protector,
maybe_enable_malloc_check in libc.a can't call the regular version of
__access_noerrno with stack protector.

This patch changes how Linux defines the __access_noerrno to be an
inline call instead and thus preventing defining different build
rules for ld/static and shared.

	H.J. Lu  <hongjiu.lu@intel.com>
	Adhemerval Zanella  <adhemerval.zanella@linaro.org>

	[BZ #21744]
	* elf/dl-tunables.c: Include not-errno.h header.
	* include/unistd.h (__access_noerrno): Remove definition.
	* sysdeps/unix/sysv/linux/access.c (__access_noerrno): Likewise.
	* sysdeps/generic/not-errno.h: New file.
	* sysdeps/unix/sysv/linux/not-errno.h: Likewise.
This commit is contained in:
Adhemerval Zanella 2017-07-17 18:11:12 -03:00
parent 422ff87c24
commit 95a7339258
6 changed files with 66 additions and 22 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
2017-07-24 Adhemerval Zanella <adhemerval.zanella@linaro.org>
H.J. Lu <hongjiu.lu@intel.com>
[BZ #21744]
* elf/dl-tunables.c: Include not-errno.h header.
* include/unistd.h (__access_noerrno): Remove definition.
* sysdeps/unix/sysv/linux/access.c (__access_noerrno): Likewise.
* sysdeps/generic/not-errno.h: New file.
* sysdeps/unix/sysv/linux/not-errno.h: Likewise.
2017-07-24 H.J. Lu <hongjiu.lu@intel.com>
[BZ #21752]

2
elf/dl-tunables.c
View File

@ -29,6 +29,8 @@
#define TUNABLES_INTERNAL 1
#include "dl-tunables.h"
#include <not-errno.h>
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
# define GLIBC_TUNABLES "GLIBC_TUNABLES"
#endif

7
include/unistd.h
View File

@ -182,12 +182,5 @@ extern int __getlogin_r_loginuid (char *name, size_t namesize)
# include <dl-unistd.h>
# endif
# if IS_IN (rtld) || !defined SHARED
/* __access variant that does not set errno. Used in very early initialization
code in libc.a and ld.so. It follows access return semantics (zero for
sucess otherwise a value different than 0). */
extern __typeof (__access) __access_noerrno attribute_hidden;
# endif
# endif
#endif

19
sysdeps/generic/not-errno.h Normal file
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@ -0,0 +1,19 @@
/* Syscall wrapper that do not set errno. Generic version.
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/>. */
extern __typeof (__access) __access_noerrno attribute_hidden;

15
sysdeps/unix/sysv/linux/access.c
View File

@ -20,21 +20,6 @@
#include <unistd.h>
#include <sysdep-cancel.h>
int
__access_noerrno (const char *file, int type)
{
int res;
INTERNAL_SYSCALL_DECL (err);
#ifdef __NR_access
res = INTERNAL_SYSCALL_CALL (access, err, file, type);
#else
res = INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, file, type);
#endif
if (INTERNAL_SYSCALL_ERROR_P (res, err))
return INTERNAL_SYSCALL_ERRNO (res, err);
return 0;
}
int
__access (const char *file, int type)
{

35
sysdeps/unix/sysv/linux/not-errno.h Normal file
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@ -0,0 +1,35 @@
/* Syscall wrapper that do not set errno. Linux version.
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/>. */
/* This function is used on maybe_enable_malloc_check (elf/dl-tunables.c)
and to avoid having to build/use multiple versions if stack protection
in enabled it is defined as inline. */
static inline int
__access_noerrno (const char *pathname, int mode)
{
int res;
INTERNAL_SYSCALL_DECL (err);
#ifdef __NR_access
res = INTERNAL_SYSCALL_CALL (access, err, pathname, mode);
#else
res = INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, pathname, mode);
#endif
if (INTERNAL_SYSCALL_ERROR_P (res, err))
return INTERNAL_SYSCALL_ERRNO (res, err);
return 0;
}