freebsd-skq/lib/libc/sys/chroot.2

.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)chroot.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt CHROOT 2
.Os
.Sh NAME
.Nm chroot
.Nd change root directory
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn chroot "const char *dirname"
.Sh DESCRIPTION
.Fa Dirname
is the address of the pathname of a directory, terminated by an ASCII NUL.
The
.Fn chroot
function causes
.Fa dirname
to become the root directory,
that is, the starting point for path searches of pathnames
beginning with
.Ql / .
.Pp
In order for a directory to become the root directory
a process must have execute (search) access for that directory.
.Pp
It should be noted that
.Fn chroot
has no effect on the process's current directory.
.Pp
This call is restricted to the super-user.
.Pp
Depending on the setting of the
.Ql kern.chroot_allow_open_directories
sysctl variable, open filedescriptors which reference directories
will make the
.Fn chroot
fail as follows:
.Pp
If
.Ql kern.chroot_allow_open_directories
is set to zero,
.Fn chroot
will always fail with
.Er EPERM
if there are any directories open.
.Pp
If
.Ql kern.chroot_allow_open_directories
is set to one (the default),
.Fn chroot
will fail with
.Er EPERM
if there are any directories open and the
process is already subject to a
.Fn chroot
call.
.Pp
Any other value for
.Ql kern.chroot_allow_open_directories
will bypass the check for open directories
.Pp
Upon successful completion, a value of 0 is returned.  Otherwise,
a value of -1 is returned and
.Va errno
is set to indicate an error.
.Sh ERRORS
The
.Fn chroot
function
will fail and the root directory will be unchanged if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path name is not a directory.
.It Bq Er EPERM
The effective user ID is not the super-user, or one or more
filedescriptors are open directories.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
The named directory does not exist.
.It Bq Er EACCES
Search permission is denied for any component of the path name.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EFAULT
.Fa Path
points outside the process's allocated address space.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr chdir 2 ,
.Xr jail 2
.Sh HISTORY
The
.Fn chroot
function call appeared in
.Bx 4.2 .
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" Copyright (c) 1983, 1991, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
			`.\" 3. All advertising materials mentioning features or use of this software`
			`.\" must display the following acknowledgement:`
			`.\" This product includes software developed by the University of`
			`.\" California, Berkeley and its contributors.`
			`.\" 4. Neither the name of the University nor the names of its contributors`
			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
			`.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\"`
			`.Dd June 4, 1993`
			`.Dt CHROOT 2`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 13:41:46 +00:00			`.Os`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh NAME`
			`.Nm chroot`
			`.Nd change root directory`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In unistd.h`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft int`
			`.Fn chroot "const char *dirname"`
			`.Sh DESCRIPTION`
			`.Fa Dirname`
			`is the address of the pathname of a directory, terminated by an ASCII NUL.`
The .Fn function. 2002-07-15 20:59:12 +00:00			`The`
			`.Fn chroot`
			`function causes`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Fa dirname`
			`to become the root directory,`
			`that is, the starting point for path searches of pathnames`
			`beginning with`
			`.Ql / .`
			`.Pp`
			`In order for a directory to become the root directory`
			`a process must have execute (search) access for that directory.`
			`.Pp`
			`It should be noted that`
			`.Fn chroot`
			`has no effect on the process's current directory.`
			`.Pp`
			`This call is restricted to the super-user.`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Pp`
			`Depending on the setting of the`
			`.Ql kern.chroot_allow_open_directories`
			`sysctl variable, open filedescriptors which reference directories`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`will make the`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Fn chroot`
			`fail as follows:`
			`.Pp`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`If`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Ql kern.chroot_allow_open_directories`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`is set to zero,`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Fn chroot`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:02:00 +00:00			`will always fail with`
			`.Er EPERM`
			`if there are any directories open.`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Pp`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`If`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Ql kern.chroot_allow_open_directories`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`is set to one (the default),`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Fn chroot`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:02:00 +00:00			`will fail with`
			`.Er EPERM`
			`if there are any directories open and the`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`process is already subject to a`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`.Fn chroot`
			`call.`
			`.Pp`
			`Any other value for`
			`.Ql kern.chroot_allow_open_directories`
			`will bypass the check for open directories`
			`.Pp`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`Upon successful completion, a value of 0 is returned. Otherwise,`
			`a value of -1 is returned and`
			`.Va errno`
			`is set to indicate an error.`
			`.Sh ERRORS`
The .Fn function. 2002-07-15 20:59:12 +00:00			`The`
			`.Fn chroot`
			`function`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`will fail and the root directory will be unchanged if:`
Use `Er' variable to define first column width in ERRORS section. It was initially suggested by mdoc(7) style, but was broken over the years 2000-05-04 13:09:25 +00:00			`.Bl -tag -width Er`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.It Bq Er ENOTDIR`
			`A component of the path name is not a directory.`
Document the possible EPERM return. Submitted by: imp@village.org (Warner Losh) 1996-04-17 20:49:29 +00:00			`.It Bq Er EPERM`
Add a sysctl variable which can help stop chroot(2) escapes. kern.chroot_allow_open_directories = 0 chroot(2) fails if there are open directories. kern.chroot_allow_open_directories = 1 (default) chroot(2) fails if there are open directories and the process is subject of a previous chroot(2). kern.chroot_allow_open_directories = anything else filedescriptors are not checked. (old behaviour). I'm very interested in reports about software which breaks when running with the default setting. 1999-03-23 14:26:40 +00:00			`The effective user ID is not the super-user, or one or more`
			`filedescriptors are open directories.`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.It Bq Er ENAMETOOLONG`
			`A component of a pathname exceeded 255 characters,`
			`or an entire path name exceeded 1023 characters.`
			`.It Bq Er ENOENT`
			`The named directory does not exist.`
			`.It Bq Er EACCES`
			`Search permission is denied for any component of the path name.`
			`.It Bq Er ELOOP`
			`Too many symbolic links were encountered in translating the pathname.`
			`.It Bq Er EFAULT`
			`.Fa Path`
			`points outside the process's allocated address space.`
			`.It Bq Er EIO`
			`An I/O error occurred while reading from or writing to the file system.`
			`.El`
			`.Sh SEE ALSO`
Add xref to jail(2). PR: docs/33177 Submitted by: Tom Rhodes <darklogik@pittgoth.com> 2001-12-28 09:26:45 +00:00			`.Xr chdir 2 ,`
			`.Xr jail 2`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh HISTORY`
			`The`
Update a bunch of man pages to use .Fn instead of .Nm when referencing funciton names. 1996-08-22 22:05:59 +00:00			`.Fn chroot`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`function call appeared in`
			`.Bx 4.2 .`