1.\" $NetBSD: chroot.2,v 1.7 1995/02/27 12:32:12 cgd Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt CHROOT 2 38.Os BSD 4.2 39.Sh NAME 40.Nm chroot 41.Nd change root directory 42.Sh SYNOPSIS 43.Fd #include <unistd.h> 44.Ft int 45.Fn chroot "const char *dirname" 46.Sh DESCRIPTION 47.Fa Dirname 48is the address of the pathname of a directory, terminated by an ASCII NUL. 49.Fn chroot 50causes 51.Fa dirname 52to become the root directory, 53that is, the starting point for path searches of pathnames 54beginning with 55.Ql / . 56.Pp 57In order for a directory to become the root directory 58a process must have execute (search) access for that directory. 59.Pp 60If the program is not currently running with an altered root directory, 61it should be noted that 62.Fn chroot 63has no effect on the process's current directory. 64.Pp 65If the program is already running with an altered root directory, the 66process's current directory is changed to the same new root directory. 67This prevents the current directory from being further up the directory 68tree than the altered root directory. 69.Pp 70This call is restricted to the super-user. 71.Sh RETURN VALUES 72Upon successful completion, a value of 0 is returned. Otherwise, 73a value of -1 is returned and 74.Va errno 75is set to indicate an error. 76.Sh ERRORS 77.Fn chroot 78will fail and the root directory will be unchanged if: 79.Bl -tag -width Er 80.It Bq Er ENOTDIR 81A component of the path name is not a directory. 82.It Bq Er ENAMETOOLONG 83A component of a pathname exceeded 84.Dv {NAME_MAX} 85characters, or an entire path name exceeded 86.Dv {PATH_MAX} 87characters. 88.It Bq Er ENOENT 89The named directory does not exist. 90.It Bq Er EACCES 91Search permission is denied for any component of the path name. 92.It Bq Er ELOOP 93Too many symbolic links were encountered in translating the pathname. 94.It Bq Er EFAULT 95.Fa Path 96points outside the process's allocated address space. 97.It Bq Er EIO 98An I/O error occurred while reading from or writing to the file system. 99.El 100.Sh SEE ALSO 101.Xr chdir 2 102.Sh WARNINGS 103There are ways for a root process to escape from the chroot jail. 104.Sh HISTORY 105The 106.Fn chroot 107function call appeared in 108.Bx 4.2 . 109