diff options
Diffstat (limited to 'csu/check_fds.c')
| -rw-r--r-- | csu/check_fds.c | 97 |
1 files changed, 0 insertions, 97 deletions
diff --git a/csu/check_fds.c b/csu/check_fds.c deleted file mode 100644 index 062c879373..0000000000 --- a/csu/check_fds.c +++ /dev/null @@ -1,97 +0,0 @@ -/* Copyright (C) 2000-2017 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/>. */ - -#include <errno.h> -#include <fcntl.h> -#include <paths.h> -#include <unistd.h> -#include <sys/stat.h> -#include <sys/sysmacros.h> - -/* 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 - -#include <device-nrs.h> -#include <not-cancel.h> - - -/* 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) -{ - /* Note that fcntl() with this parameter is not a cancellation point. */ - if (__builtin_expect (__libc_fcntl (fd, F_GETFD), 0) == -1 - && errno == EBADF) - { - const char *name; - dev_t dev; - - /* For writable descriptors we use /dev/full. */ - if ((mode & O_ACCMODE) == O_WRONLY) - { - name = _PATH_DEV "full"; - dev = makedev (DEV_FULL_MAJOR, DEV_FULL_MINOR); - } - else - { - name = _PATH_DEVNULL; - dev = makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR); - } - - /* 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 accidentally use this descriptor. */ - int nullfd = open_not_cancel (name, mode, 0); - - /* We are very paranoid here. With all means we try to ensure - that we are actually opening the /dev/null device and nothing - else. - - Note that the following code assumes that STDIN_FILENO, - STDOUT_FILENO, STDERR_FILENO are the three lowest file - decsriptor numbers, in this order. */ - struct stat64 st; - if (__builtin_expect (nullfd != fd, 0) - || __builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) != 0 - || __builtin_expect (S_ISCHR (st.st_mode), 1) == 0 - || st.st_rdev != dev) - /* 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) -{ - /* Check all three standard file descriptors. The O_NOFOLLOW flag - 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" we bail out. */ - check_one_fd (STDIN_FILENO, O_WRONLY | O_NOFOLLOW); - check_one_fd (STDOUT_FILENO, O_RDONLY | O_NOFOLLOW); - check_one_fd (STDERR_FILENO, O_RDONLY | O_NOFOLLOW); -} |