CHROOT(2) System Calls CHROOT(2)
NAME
chroot, fchroot - change root directory
SYNOPSIS
#include <unistd.h>
int chroot(
const char *path);
int fchroot(
int fildes);
DESCRIPTION
The
chroot() and
fchroot() functions cause a directory to become the
root directory, the starting point for path searches for path names
beginning with
/ (slash). The user's working directory is unaffected by
the
chroot() and
fchroot() functions.
The
path argument points to a path name naming a directory. The
fildes argument to
fchroot() is the open file descriptor of the directory which
is to become the root.
The privilege {
PRIV_PROC_CHROOT} must be asserted in the effective set of
the process to change the root directory. While it is always possible to
change to the system root using the
fchroot() function, it is not
guaranteed to succeed in any other case, even if
fildes is valid in all
respects.
The ".." entry in the root directory is interpreted to mean the root
directory itself. Therefore, ".." cannot be used to access files outside
the subtree rooted at the root directory. Instead,
fchroot() can be used
to reset the root to a directory that was opened before the root
directory was changed.
RETURN VALUES
Upon successful completion,
0 is returned. Otherwise,
-1 is returned, the
root directory remains unchanged, and
errno is set to indicate the error.
ERRORS
The
chroot() function will fail if:
EACCES Search permission is denied for a component of the path
prefix of
dirname, or search permission is denied for the
directory referred to by
dirname.
EBADF The descriptor is not valid.
EFAULT The
path argument points to an illegal address.
EINVAL The
fchroot() function attempted to change to a directory
the is not the system root and external circumstances do
not allow this.
EINTR A signal was caught during the execution of the
chroot() function.
EIO An I/O error occurred while reading from or writing to
the file system.
ELOOP Too many symbolic links were encountered in translating
path.
ENAMETOOLONG The length of the
path argument exceeds
PATH_MAX, or the
length of a
path component exceeds
NAME_MAX while
_POSIX_NO_TRUNC is in effect.
ENOENT The named directory does not exist or is a null pathname.
ENOLINK The
path argument points to a remote machine and the link
to that machine is no longer active.
ENOTDIR Any component of the path name is not a directory.
EPERM The {
PRIV_PROC_CHROOT} privilege is not asserted in the
effective set of the calling process.
SEE ALSO
chdir(2),
privileges(7),
chroot(8)WARNINGS
The only use of
fchroot() that is appropriate is to change back to the
system root.
January 20, 2003
CHROOT(2)