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.\" 34.Dd June 4, 1993 35.Dt CHROOT 2 36.Os BSD 4.2 37.Sh NAME 38.Nm chroot 39.Nd change root directory 40.Sh SYNOPSIS 41.Fd #include <unistd.h> 42.Ft int 43.Fn chroot "const char *dirname" 44.Sh DESCRIPTION 45.Fa Dirname 46is the address of the pathname of a directory, terminated by an ASCII NUL. 47.Fn Chroot 48causes 49.Fa dirname 50to become the root directory, 51that is, the starting point for path searches of pathnames 52beginning with 53.Ql / . 54.Pp 55In order for a directory to become the root directory 56a process must have execute (search) access for that directory. 57.Pp 58It should be noted that 59.Fn chroot 60has no effect on the process's current directory. 61.Pp 62This call is restricted to the super-user. 63.Pp 64Depending on the setting of the 65.Ql kern.chroot_allow_open_directories 66sysctl variable, open filedescriptors which reference directories 67will make the 68.Fn chroot 69fail as follows: 70.Pp 71If 72.Ql kern.chroot_allow_open_directories 73is set to zero, 74.Fn chroot 75will always fail with EPERM if there are any directories open. 76.Pp 77If 78.Ql kern.chroot_allow_open_directories 79is set to one (the default), 80.Fn chroot 81will fail with EPERM if there are any directories open and the 82process is already subject to a 83.Fn chroot 84call. 85.Pp 86Any other value for 87.Ql kern.chroot_allow_open_directories 88will bypass the check for open directories 89.Pp 90Upon successful completion, a value of 0 is returned. Otherwise, 91a value of -1 is returned and 92.Va errno 93is set to indicate an error. 94.Sh ERRORS 95.Fn Chroot 96will fail and the root directory will be unchanged if: 97.Bl -tag -width [ENOTDIR] 98.It Bq Er ENOTDIR 99A component of the path name is not a directory. 100.It Bq Er EPERM 101The effective user ID is not the super-user, or one or more 102filedescriptors are open directories. 103.It Bq Er ENAMETOOLONG 104A component of a pathname exceeded 255 characters, 105or an entire path name exceeded 1023 characters. 106.It Bq Er ENOENT 107The named directory does not exist. 108.It Bq Er EACCES 109Search permission is denied for any component of the path name. 110.It Bq Er ELOOP 111Too many symbolic links were encountered in translating the pathname. 112.It Bq Er EFAULT 113.Fa Path 114points outside the process's allocated address space. 115.It Bq Er EIO 116An I/O error occurred while reading from or writing to the file system. 117.El 118.Sh SEE ALSO 119.Xr chdir 2 120.Sh HISTORY 121The 122.Fn chroot 123function call appeared in 124.Bx 4.2 . 125