# chroot

## NAME



           chroot - change root directory
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#include <unistd.h>**
    
           **int chroot(const char ***_path_**);**
    
       Feature Test Macro Requirements for glibc (see
       feature_test_macros(7)):
    
           **chroot**():
               Since glibc 2.2.2:
                   _XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
                       || /* Since glibc 2.20: */ _DEFAULT_SOURCE
                       || /* glibc <= 2.19: */ _BSD_SOURCE
               Before glibc 2.2.2:
                   none
    


## DESCRIPTION



           **chroot**() changes the root directory of the calling process to that
           specified in _path_.  This directory will be used for pathnames
           beginning with _/_.  The root directory is inherited by all children
           of the calling process.
    
           Only a privileged process (Linux: one with the **CAP_SYS_CHROOT**
           capability in its user namespace) may call **chroot**().
    
           This call changes an ingredient in the pathname resolution process
           and does nothing else.  In particular, it is not intended to be
           used for any kind of security purpose, neither to fully sandbox a
           process nor to restrict filesystem system calls.  In the past,
           **chroot**() has been used by daemons to restrict themselves prior to
           passing paths supplied by untrusted users to system calls such as
           open(2).  However, if a folder is moved out of the chroot
           directory, an attacker can exploit that to get out of the chroot
           directory as well.  The easiest way to do that is to chdir(2) to
           the to-be-moved directory, wait for it to be moved out, then open
           a path like ../../../etc/passwd.
    
           A slightly trickier variation also works under some circumstances
           if chdir(2) is not permitted.  If a daemon allows a "chroot
           directory" to be specified, that usually means that if you want to
           prevent remote users from accessing files outside the chroot
           directory, you must ensure that folders are never moved out of it.
    
           This call does not change the current working directory, so that
           after the call '_._ ' can be outside the tree rooted at '_/_ '.  In
           particular, the superuser can escape from a "chroot jail" by
           doing:
    
               mkdir foo; chroot foo; cd ..
    
           This call does not close open file descriptors, and such file
           descriptors may allow access to files outside the chroot tree.
    


## RETURN VALUE



           On success, zero is returned.  On error, -1 is returned, and _errno_
           is set to indicate the error.
    


## ERRORS



           Depending on the filesystem, other errors can be returned.  The
           more general errors are listed below:
    
           **EACCES** Search permission is denied on a component of the path
                  prefix.  (See also path_resolution(7).)
    
           **EFAULT** _path_ points outside your accessible address space.
    
           **EIO** An I/O error occurred.
    
           **ELOOP** Too many symbolic links were encountered in resolving _path_.
    
           **ENAMETOOLONG**
                  _path_ is too long.
    
           **ENOENT** The file does not exist.
    
           **ENOMEM** Insufficient kernel memory was available.
    
           **ENOTDIR**
                  A component of _path_ is not a directory.
    
           **EPERM** The caller has insufficient privilege.
    


## STANDARDS



           None.
    


## NOTES



           A child process created via fork(2) inherits its parent's root
           directory.  The root directory is left unchanged by execve(2).
    
           The magic symbolic link, _/proc/_ pid _/root_ , can be used to discover a
           process's root directory; see proc(5) for details.
    
           FreeBSD has a stronger **jail**() system call.
    


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