Don't all __access_noerrno with stack protector from __tunables_init [BZ #21744]

  On Tue, Jul 18, 2017 at 6:52 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
> On 18/07/2017 10:44, H.J. Lu wrote:
>> This should work for Linux.
>>
>> Thanks.
>>
>
> Now with a proper patch:
>
> [PATCH] tunables: Use direct syscall for access (BZ#21744)
>
> 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>

Missing [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.
> ---
>  ChangeLog                           |  9 +++++++++
>  elf/dl-tunables.c                   |  2 ++
>  include/unistd.h                    |  7 -------
>  sysdeps/generic/not-errno.h         | 19 +++++++++++++++++++
>  sysdeps/unix/sysv/linux/access.c    | 15 ---------------
>  sysdeps/unix/sysv/linux/not-errno.h | 30 ++++++++++++++++++++++++++++++
>  6 files changed, 60 insertions(+), 22 deletions(-)
>  create mode 100644 sysdeps/generic/not-errno.h
>  create mode 100644 sysdeps/unix/sysv/linux/not-errno.h
>
> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
> index 44c160c..231fb8c 100644
> --- a/elf/dl-tunables.c
> +++ b/elf/dl-tunables.c
> @@ -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
> diff --git a/include/unistd.h b/include/unistd.h
> index 5b2a414..7f1c2cc 100644
> --- a/include/unistd.h
> +++ b/include/unistd.h
> @@ -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
> diff --git a/sysdeps/generic/not-errno.h b/sysdeps/generic/not-errno.h
> new file mode 100644
> index 0000000..2aac095
> --- /dev/null
> +++ b/sysdeps/generic/not-errno.h
> @@ -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;
> diff --git a/sysdeps/unix/sysv/linux/access.c b/sysdeps/unix/sysv/linux/access.c
> index 67e69bd..366b6b6 100644
> --- a/sysdeps/unix/sysv/linux/access.c
> +++ b/sysdeps/unix/sysv/linux/access.c
> @@ -21,21 +21,6 @@
>  #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)
>  {
>  #ifdef __NR_access
> diff --git a/sysdeps/unix/sysv/linux/not-errno.h b/sysdeps/unix/sysv/linux/not-errno.h
> new file mode 100644
> index 0000000..4957038
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/not-errno.h
> @@ -0,0 +1,30 @@
> +/* 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)
> +{
> +#ifdef __NR_access
> +  return INTERNAL_SYSCALL_CALL (access, pathname, mode);
> +#else
> +  return INTERNAL_SYSCALL_CALL (faccessat, AT_FDCWD, file, type);
> +#endif
> +}

These are wrong.  INTERNAL_SYSCALL_CALL needs  a dummy err.
This seems to work:

Don't all __access_noerrno with stack protector from __tunables_init [BZ #21744]

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