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: src/lib/libc/sys/chroot.2,v 1.7.2.8 2002/12/11 14:06:37 ru Exp $ 34.\" 35.Dd June 4, 1993 36.Dt CHROOT 2 37.Os 38.Sh NAME 39.Nm chroot 40.Nd change root directory 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In 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 79.Er EPERM 80if there are any directories open. 81.Pp 82If 83.Ql kern.chroot_allow_open_directories 84is set to one (the default), 85.Fn chroot 86will fail with 87.Er EPERM 88if there are any directories open and the 89process is already subject to a 90.Fn chroot 91call. 92.Pp 93Any other value for 94.Ql kern.chroot_allow_open_directories 95will bypass the check for open directories 96.Pp 97Upon successful completion, a value of 0 is returned. Otherwise, 98a value of -1 is returned and 99.Va errno 100is set to indicate an error. 101.Sh ERRORS 102.Fn Chroot 103will fail and the root directory will be unchanged if: 104.Bl -tag -width Er 105.It Bq Er ENOTDIR 106A component of the path name is not a directory. 107.It Bq Er EPERM 108The effective user ID is not the super-user, or one or more 109filedescriptors are open directories. 110.It Bq Er ENAMETOOLONG 111A component of a pathname exceeded 255 characters, 112or an entire path name exceeded 1023 characters. 113.It Bq Er ENOENT 114The named directory does not exist. 115.It Bq Er EACCES 116Search permission is denied for any component of the path name. 117.It Bq Er ELOOP 118Too many symbolic links were encountered in translating the pathname. 119.It Bq Er EFAULT 120.Fa dirname 121points outside the process's allocated address space. 122.It Bq Er EIO 123An I/O error occurred while reading from or writing to the file system. 124.El 125.Sh SEE ALSO 126.Xr chdir 2 , 127.Xr jail 2 128.Sh HISTORY 129The 130.Fn chroot 131function call appeared in 132.Bx 4.2 . 133