1.\" $OpenBSD: chroot.2,v 1.10 2000/10/18 05:12:08 aaron Exp $ 2.\" $NetBSD: chroot.2,v 1.7 1995/02/27 12:32:12 cgd Exp $ 3.\" 4.\" Copyright (c) 1983, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93 36.\" 37.Dd June 4, 1993 38.Dt CHROOT 2 39.Os 40.Sh NAME 41.Nm chroot 42.Nd change root directory 43.Sh SYNOPSIS 44.Fd #include <unistd.h> 45.Ft int 46.Fn chroot "const char *dirname" 47.Sh DESCRIPTION 48.Fa dirname 49is the address of the pathname of a directory, terminated by an 50.Tn ASCII 51NUL. 52.Fn chroot 53causes 54.Fa dirname 55to become the root directory, that is, the starting point for path 56searches of pathnames beginning with 57.Ql / . 58.Pp 59In order for a directory to become the root directory 60a process must have execute (search) access for that directory. 61.Pp 62If the program is not currently running with an altered root directory, 63it should be noted that 64.Fn chroot 65has no effect on the process's current directory. 66.Pp 67If the program is already running with an altered root directory, the 68process's current directory is changed to the same new root directory. 69This prevents the current directory from being further up the directory 70tree than the altered root directory. 71.Pp 72This call is restricted to the superuser. 73.Sh RETURN VALUES 74Upon successful completion, a value of 0 is returned. 75Otherwise, a value of \-1 is returned and 76.Va errno 77is set to indicate an error. 78.Sh ERRORS 79.Fn chroot 80will fail and the root directory will be unchanged if: 81.Bl -tag -width Er 82.It Bq Er ENOTDIR 83A component of the path name is not a directory. 84.It Bq Er ENAMETOOLONG 85A component of a pathname exceeded 86.Dv {NAME_MAX} 87characters, or an entire path name exceeded 88.Dv {PATH_MAX} 89characters. 90.It Bq Er ENOENT 91The named directory does not exist. 92.It Bq Er EACCES 93Search permission is denied for any component of the path name. 94.It Bq Er ELOOP 95Too many symbolic links were encountered in translating the pathname. 96.It Bq Er EFAULT 97.Fa dirname 98points outside the process's allocated address space. 99.It Bq Er EIO 100An I/O error occurred while reading from or writing to the file system. 101.El 102.Sh SEE ALSO 103.Xr chdir 2 104.Sh WARNINGS 105There are ways for a root process to escape from the chroot jail. 106.Sh HISTORY 107The 108.Fn chroot 109function call appeared in 110.Bx 4.2 . 111