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.\" $FreeBSD$ 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 LIBRARY 42.Lb libc 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 ASCII NUL. 50.Fn Chroot 51causes 52.Fa dirname 53to become the root directory, 54that is, the starting point for path searches of pathnames 55beginning with 56.Ql / . 57.Pp 58In order for a directory to become the root directory 59a process must have execute (search) access for that directory. 60.Pp 61It should be noted that 62.Fn chroot 63has no effect on the process's current directory. 64.Pp 65This call is restricted to the super-user. 66.Pp 67Depending on the setting of the 68.Ql kern.chroot_allow_open_directories 69sysctl variable, open filedescriptors which reference directories 70will make the 71.Fn chroot 72fail as follows: 73.Pp 74If 75.Ql kern.chroot_allow_open_directories 76is set to zero, 77.Fn chroot 78will always fail with EPERM if there are any directories open. 79.Pp 80If 81.Ql kern.chroot_allow_open_directories 82is set to one (the default), 83.Fn chroot 84will fail with EPERM if there are any directories open and the 85process is already subject to a 86.Fn chroot 87call. 88.Pp 89Any other value for 90.Ql kern.chroot_allow_open_directories 91will bypass the check for open directories 92.Pp 93Upon successful completion, a value of 0 is returned. Otherwise, 94a value of -1 is returned and 95.Va errno 96is set to indicate an error. 97.Sh ERRORS 98.Fn Chroot 99will fail and the root directory will be unchanged if: 100.Bl -tag -width Er 101.It Bq Er ENOTDIR 102A component of the path name is not a directory. 103.It Bq Er EPERM 104The effective user ID is not the super-user, or one or more 105filedescriptors are open directories. 106.It Bq Er ENAMETOOLONG 107A component of a pathname exceeded 255 characters, 108or an entire path name exceeded 1023 characters. 109.It Bq Er ENOENT 110The named directory does not exist. 111.It Bq Er EACCES 112Search permission is denied for any component of the path name. 113.It Bq Er ELOOP 114Too many symbolic links were encountered in translating the pathname. 115.It Bq Er EFAULT 116.Fa Path 117points outside the process's allocated address space. 118.It Bq Er EIO 119An I/O error occurred while reading from or writing to the file system. 120.El 121.Sh SEE ALSO 122.Xr chdir 2 123.Sh HISTORY 124The 125.Fn chroot 126function call appeared in 127.Bx 4.2 . 128