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 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. 50The 51.Fn chroot 52function causes 53.Fa dirname 54to become the root directory, 55that is, the starting point for path searches of pathnames 56beginning 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 62It should be noted that 63.Fn chroot 64has no effect on the process's current directory. 65.Pp 66This call is restricted to the super-user. 67.Pp 68Depending on the setting of the 69.Ql kern.chroot_allow_open_directories 70sysctl variable, open filedescriptors which reference directories 71will make the 72.Fn chroot 73fail as follows: 74.Pp 75If 76.Ql kern.chroot_allow_open_directories 77is set to zero, 78.Fn chroot 79will always fail with 80.Er EPERM 81if there are any directories open. 82.Pp 83If 84.Ql kern.chroot_allow_open_directories 85is set to one (the default), 86.Fn chroot 87will fail with 88.Er EPERM 89if there are any directories open and the 90process is already subject to a 91.Fn chroot 92call. 93.Pp 94Any other value for 95.Ql kern.chroot_allow_open_directories 96will bypass the check for open directories 97.Pp 98Upon successful completion, a value of 0 is returned. Otherwise, 99a value of -1 is returned and 100.Va errno 101is set to indicate an error. 102.Sh ERRORS 103The 104.Fn chroot 105function 106will fail and the root directory will be unchanged if: 107.Bl -tag -width Er 108.It Bq Er ENOTDIR 109A component of the path name is not a directory. 110.It Bq Er EPERM 111The effective user ID is not the super-user, or one or more 112filedescriptors are open directories. 113.It Bq Er ENAMETOOLONG 114A component of a pathname exceeded 255 characters, 115or an entire path name exceeded 1023 characters. 116.It Bq Er ENOENT 117The named directory does not exist. 118.It Bq Er EACCES 119Search permission is denied for any component of the path name. 120.It Bq Er ELOOP 121Too many symbolic links were encountered in translating the pathname. 122.It Bq Er EFAULT 123.Fa Path 124points outside the process's allocated address space. 125.It Bq Er EIO 126An I/O error occurred while reading from or writing to the file system. 127.El 128.Sh SEE ALSO 129.Xr chdir 2 , 130.Xr jail 2 131.Sh HISTORY 132The 133.Fn chroot 134function call appeared in 135.Bx 4.2 . 136