2000-05-25 07:02:35 +02:00
|
|
|
/* Copyright (C) 2000 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 Library General Public License as
|
|
|
|
published by the Free Software Foundation; either version 2 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
|
|
|
|
Library General Public License for more details.
|
|
|
|
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
|
|
|
|
#include <errno.h>
|
|
|
|
#include <fcntl.h>
|
|
|
|
#include <paths.h>
|
|
|
|
#include <unistd.h>
|
2000-09-26 08:42:06 +02:00
|
|
|
#include <sys/stat.h>
|
|
|
|
#include <sys/sysmacros.h>
|
2000-05-25 07:02:35 +02:00
|
|
|
|
|
|
|
/* Try to get a machine dependent instruction which will make the
|
|
|
|
program crash. This is used in case everything else fails. */
|
|
|
|
#include <abort-instr.h>
|
|
|
|
#ifndef ABORT_INSTRUCTION
|
|
|
|
/* No such instruction is available. */
|
|
|
|
# define ABORT_INSTRUCTION
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
|
|
/* Should other OSes (e.g., Hurd) have different versions which can
|
|
|
|
be written in a better way? */
|
|
|
|
static void
|
|
|
|
check_one_fd (int fd, int mode)
|
|
|
|
{
|
|
|
|
if (__builtin_expect (__libc_fcntl (fd, F_GETFD), 0) == -1
|
|
|
|
&& errno == EBADF)
|
|
|
|
{
|
2000-09-26 08:42:06 +02:00
|
|
|
struct stat64 st;
|
|
|
|
|
2000-05-25 07:02:35 +02:00
|
|
|
/* Something is wrong with this descriptor, it's probably not
|
|
|
|
opened. Open /dev/null so that the SUID program we are
|
|
|
|
about to start does not accidently use this descriptor. */
|
|
|
|
int nullfd = __libc_open (_PATH_DEVNULL, mode);
|
2000-09-26 08:42:06 +02:00
|
|
|
/* We are very paranoid here. With all means we try to ensure
|
|
|
|
that we are actually opening the /dev/null device and nothing
|
|
|
|
else. */
|
|
|
|
if (__builtin_expect (nullfd, 0) == -1
|
|
|
|
|| __builtin_expect (__fxstat64 (_STAT_VER, nullfd, &st), 0) != 0
|
|
|
|
|| __builtin_expect (S_ISCHR (st.st_mode), 1) == 0
|
|
|
|
#if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
|
|
|
|
|| st.st_rdev != makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
|
|
|
|
#endif
|
|
|
|
)
|
2000-05-25 07:02:35 +02:00
|
|
|
/* We cannot even give an error message here since it would
|
|
|
|
run into the same problems. */
|
|
|
|
while (1)
|
|
|
|
/* Try for ever and ever. */
|
|
|
|
ABORT_INSTRUCTION;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
void
|
|
|
|
__libc_check_standard_fds (void)
|
|
|
|
{
|
2000-09-26 08:42:06 +02:00
|
|
|
/* This is really paranoid but some people actually are. If /dev/null
|
|
|
|
should happen to be a symlink to somewhere else and not the device
|
|
|
|
commonly known as "/dev/null" be bail out. We can detect this with
|
|
|
|
the O_NOFOLLOW flag for open() but only on some system. */
|
|
|
|
#ifndef O_NOFOLLOW
|
|
|
|
# define O_NOFOLLOW 0
|
|
|
|
#endif
|
|
|
|
/* Check all three standard file descriptors. */
|
|
|
|
check_one_fd (STDIN_FILENO, O_RDONLY | O_NOFOLLOW);
|
|
|
|
check_one_fd (STDOUT_FILENO, O_RDWR | O_NOFOLLOW);
|
|
|
|
check_one_fd (STDERR_FILENO, O_RDWR | O_NOFOLLOW);
|
2000-05-25 07:02:35 +02:00
|
|
|
}
|