Re: [PATCH] posix: Deprecate group_member for Linux

[Joe Simmons-Talbott <josimmon@redhat.com>]

On Thu, Sep 21, 2023 at 12:20:53PM -0400, Joe Simmons-Talbott wrote:
> The alloca usage in group_member could lead to stack overflow on Linux.
> Removing the alloca usage would require group_member to handle the error
> condition where memory could not be allocated and that cannot be done
> since group_member returns a boolean.  Thus deprecate group_member.  Add
> a testcase.

Ping.

> ---
>  posix/Makefile                         |  3 ++
>  posix/group_member.h                   | 26 ++++++++++++++++
>  posix/tst-group_member.c               | 41 ++++++++++++++++++++++++++
>  posix/unistd.h                         |  6 ++--
>  sysdeps/unix/sysv/linux/group_member.h | 27 +++++++++++++++++
>  5 files changed, 100 insertions(+), 3 deletions(-)
>  create mode 100644 posix/group_member.h
>  create mode 100644 posix/tst-group_member.c
>  create mode 100644 sysdeps/unix/sysv/linux/group_member.h
> 
> diff --git a/posix/Makefile b/posix/Makefile
> index 905cf9fb54..b7fffdd2fe 100644
> --- a/posix/Makefile
> +++ b/posix/Makefile
> @@ -294,6 +294,7 @@ tests := \
>    tst-glob_symlinks \
>    tst-gnuglob \
>    tst-gnuglob64 \
> +  tst-group_member \
>    tst-mmap \
>    tst-mmap-offset \
>    tst-nanosleep \
> @@ -615,6 +616,8 @@ bug-glob1-ARGS = "$(objpfx)"
>  tst-execvp3-ARGS = --test-dir=$(objpfx)
>  CFLAGS-tst-spawn3.c += -DOBJPFX=\"$(objpfx)\"
>  
> +CFLAGS-tst-group_member.c += -Wno-error=deprecated-declarations
> +
>  # Test voluntarily overflows struct dirent
>  CFLAGS-bug-glob2.c += $(no-fortify-source)
>  
> diff --git a/posix/group_member.h b/posix/group_member.h
> new file mode 100644
> index 0000000000..83d5220f2d
> --- /dev/null
> +++ b/posix/group_member.h
> @@ -0,0 +1,26 @@
> +/* Copyright (C) 2023 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _GROUP_MEMBER_H
> +#define _GROUP_MEMBER_H 1
> +
> +#ifdef	__USE_GNU
> +/* Return nonzero iff the calling process is in group GID.  */
> +extern int group_member (__gid_t __gid) __THROW;
> +#endif
> +
> +#endif /* GROUP_MEMBER_H */
> diff --git a/posix/tst-group_member.c b/posix/tst-group_member.c
> new file mode 100644
> index 0000000000..7f70841832
> --- /dev/null
> +++ b/posix/tst-group_member.c
> @@ -0,0 +1,41 @@
> +/* Basic tests for group_member.
> +   Copyright (C) 2023 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <alloca.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +
> +#include <support/check.h>
> +
> +static int do_test (void)
> +{
> +  int n;
> +  gid_t *groups;
> +
> +  n = getgroups (0, NULL);
> +  groups = alloca (n * sizeof (*groups));
> +  n = getgroups (n, groups);
> +
> +  while (n-- > 0)
> +    TEST_COMPARE (1, group_member(groups[n]));
> +
> +  return EXIT_SUCCESS;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/posix/unistd.h b/posix/unistd.h
> index 0477527a60..d73a9eeea2 100644
> --- a/posix/unistd.h
> +++ b/posix/unistd.h
> @@ -710,10 +710,10 @@ extern __gid_t getegid (void) __THROW;
>     of its supplementary groups in LIST and return the number written.  */
>  extern int getgroups (int __size, __gid_t __list[]) __THROW __wur
>      __fortified_attr_access (__write_only__, 2, 1);
> +
>  #ifdef	__USE_GNU
> -/* Return nonzero iff the calling process is in group GID.  */
> -extern int group_member (__gid_t __gid) __THROW;
> -#endif
> +# include <group_member.h>
> +#endif 
>  
>  /* Set the user ID of the calling process to UID.
>     If the calling process is the super-user, set the real
> diff --git a/sysdeps/unix/sysv/linux/group_member.h b/sysdeps/unix/sysv/linux/group_member.h
> new file mode 100644
> index 0000000000..9b24569d4e
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/group_member.h
> @@ -0,0 +1,27 @@
> +/* Copyright (C) 2023 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _GROUP_MEMBER_H
> +#define _GROUP_MEMBER_H 1
> +
> +#ifdef	__USE_GNU
> +/* Return nonzero iff the calling process is in group GID.  Deprecated */
> +extern int group_member (__gid_t __gid) __THROW
> +	__attribute_deprecated__;
> +#endif
> +
> +#endif /* GROUP_MEMBER_H */
> -- 
> 2.39.2
>