1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93 33.\" $Id$ 34.\" 35.Dd June 4, 1993 36.Dt CHROOT 2 37.Os BSD 4.2 38.Sh NAME 39.Nm chroot 40.Nd change root directory 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft int 44.Fn chroot "const char *dirname" 45.Sh DESCRIPTION 46.Fa Dirname 47is the address of the pathname of a directory, terminated by an ASCII NUL. 48.Fn Chroot 49causes 50.Fa dirname 51to become the root directory, 52that is, the starting point for path searches of pathnames 53beginning with 54.Ql / . 55.Pp 56In order for a directory to become the root directory 57a process must have execute (search) access for that directory. 58.Pp 59It should be noted that 60.Fn chroot 61has no effect on the process's current directory. 62.Pp 63This call is restricted to the super-user. 64.Pp 65Depending on the setting of the 66.Ql kern.chroot_allow_open_directories 67sysctl variable, open filedescriptors which reference directories 68will make the 69.Fn chroot 70fail as follows: 71.Pp 72If 73.Ql kern.chroot_allow_open_directories 74is set to zero, 75.Fn chroot 76will always fail with EPERM if there are any directories open. 77.Pp 78If 79.Ql kern.chroot_allow_open_directories 80is set to one (the default), 81.Fn chroot 82will fail with EPERM if there are any directories open and the 83process is already subject to a 84.Fn chroot 85call. 86.Pp 87Any other value for 88.Ql kern.chroot_allow_open_directories 89will bypass the check for open directories 90.Pp 91Upon successful completion, a value of 0 is returned. Otherwise, 92a value of -1 is returned and 93.Va errno 94is set to indicate an error. 95.Sh ERRORS 96.Fn Chroot 97will fail and the root directory will be unchanged if: 98.Bl -tag -width [ENOTDIR] 99.It Bq Er ENOTDIR 100A component of the path name is not a directory. 101.It Bq Er EPERM 102The effective user ID is not the super-user, or one or more 103filedescriptors are open directories. 104.It Bq Er ENAMETOOLONG 105A component of a pathname exceeded 255 characters, 106or an entire path name exceeded 1023 characters. 107.It Bq Er ENOENT 108The named directory does not exist. 109.It Bq Er EACCES 110Search permission is denied for any component of the path name. 111.It Bq Er ELOOP 112Too many symbolic links were encountered in translating the pathname. 113.It Bq Er EFAULT 114.Fa Path 115points outside the process's allocated address space. 116.It Bq Er EIO 117An I/O error occurred while reading from or writing to the file system. 118.El 119.Sh SEE ALSO 120.Xr chdir 2 121.Sh HISTORY 122The 123.Fn chroot 124function call appeared in 125.Bx 4.2 . 126