+++ /dev/null
-/* like chmod(2), but safer, if possible
- Copyright (C) 2005 Free Software Foundation, Inc.
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
-
- This program 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 General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
-
-/* written by Jim Meyering */
-
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-
-#include "chmod-safer.h"
-
-#ifdef S_IFMT
-# define defined_S_IFMT true
-#else
-# define defined_S_IFMT false
-#endif
-
-#include "stat-macros.h"
-
-#include <stdbool.h>
-#include <stdlib.h>
-#include <fcntl.h>
-#include <errno.h>
-#include <unistd.h>
-
-#ifndef O_NOFOLLOW
-# define O_NOFOLLOW 0
-#endif
-
-#ifndef HAVE_FCHMOD
-# define HAVE_FCHMOD false
-# define fchmod(fd, mode) (-1)
-#endif
-
-/* Return true if the file corresponding to stat buffer pointer ST is of type,
- TYPE, and if its major and minor device numbers match (if appropriate:
- when the type is S_IFIFO or S_IFBLK). */
-static inline bool
-same_file_type (struct stat const *st, dev_t device, mode_t type)
-{
- /* The types must always match. */
- if (! (defined_S_IFMT ? (st->st_mode & S_IFMT) == type
- : type == S_IFDIR ? S_ISDIR (st->st_mode)
- : type == S_IFIFO ? S_ISFIFO (st->st_mode)
- : type == S_IFBLK ? S_ISBLK (st->st_mode)
- : type == S_IFCHR ? S_ISCHR (st->st_mode)
- : (abort (), false)))
- return false;
-
- /* For character and block devices, the major and minor device
- numbers must match, too. */
- if (S_ISBLK (type) || S_ISCHR (type))
- return st->st_rdev == device;
-
- return true;
-}
-
-/* Assuming we can use open-with-O_NOFOLLOW and fchmod, set the permissions
- of FILE to MODE, using fchmod -- but fail (setting errno to EACCES) if
- anyone hard-links to FILE, replaces it with a symlink, or otherwise
- changes its type. Return zero upon success. */
-static int
-fchmod_new (char const *file, mode_t mode, dev_t device, mode_t file_type)
-{
- int result = 0;
- struct stat sb;
- int fd = open (file, O_RDONLY | O_NOCTTY | O_NOFOLLOW | O_NONBLOCK);
- int saved_errno;
-
- if (fd < 0)
- return -1;
-
- /* Given the entry we've just created, if its link count is
- not 1 or its type/device has changed, then someone may be
- trying to do something nasty. However, the risk of such an
- attack is so low that it isn't worth a special diagnostic.
- Simply skip the fchmod and set errno, so that the
- code below reports the failure to set permissions.
- Note that we don't check the link count if the expected
- type is `directory'. */
- result = fstat (fd, &sb);
- if (result == 0)
- {
- if ((sb.st_nlink == 1 || S_ISDIR (file_type))
- && same_file_type (&sb, device, file_type))
- result = fchmod (fd, mode);
- else
- {
- errno = EACCES;
- result = -1;
- }
- }
-
- saved_errno = errno;
- close (fd);
- errno = saved_errno;
- return result;
-}
-
-/* Use a safer variant of chmod, if the underlying system facilities permit.
- This can avoid a minor race condition between when a file/device/directory
- is created and when we set its permissions. If the system provides an
- fchmod function and if its open syscall honors the O_NOFOLLOW flag, then
- use open,fchmod,close. Otherwise, just call chmod. FILE and MODE are
- just as for chmod. DEVICE is the combination (a la stat.st_rdev) of major
- and minor device numbers. FILE_TYPE is one of the S_IF* values, e.g.,
- S_IFBLK, S_IFCHR, etc. */
-int
-chmod_safer (char const *file, mode_t mode, dev_t device, mode_t file_type)
-{
- /* Using open and fchmod is reliable only if open honors the O_NOFOLLOW
- flag. Otherwise, an attacker could simply replace the just-created
- entry with a symlink, and open would follow it blindly. */
- return (HAVE_FCHMOD && O_NOFOLLOW
- ? fchmod_new (file, mode, device, file_type)
- : chmod (file, mode));
-}
+++ /dev/null
-/* like chmod(2), but safer, if possible
- Copyright (C) 2005 Free Software Foundation, Inc.
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
-
- This program 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 General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
-
-/* Written by Jim Meyering. */
-
-#ifndef FCHMOD_SAFER_H
-# define FCHMOD_SAFER_H 1
-
-# include <sys/types.h>
-# include <sys/stat.h>
-
-int chmod_safer (char const *file, mode_t mode, dev_t device, mode_t file_type);
-
-#endif /* FCHMOD_SAFER_H */
projects / platform / upstream / coreutils.git / commitdiff