[apple/xnu.git] / bsd / man / man2 / chroot.2

.\"	$NetBSD: chroot.2,v 1.7 1995/02/27 12:32:12 cgd Exp $
.\"
.\" 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
.\"
.Dd June 4, 1993
.Dt CHROOT 2
.Os BSD 4.2
.Sh NAME
.Nm chroot
.Nd change root directory
.Sh SYNOPSIS
.Fd #include <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.
.Fn Chroot
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
If the program is not currently running with an altered root directory,
it should be noted that
.Fn chroot
has no effect on the process's current directory.
.Pp
If the program is already running with an altered root directory, the
process's current directory is changed to the same new root directory.
This prevents the current directory from being further up the directory
tree than the altered root directory.
.Pp
This call is restricted to the super-user.
.Sh RETURN VALUES
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
.Fn Chroot
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 ENAMETOOLONG
A component of a pathname exceeded 
.Dv {NAME_MAX}
characters, or an entire path name exceeded 
.Dv {PATH_MAX}
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
.Sh WARNINGS
There are ways for a root process to escape from the chroot jail.
.Sh HISTORY
The
.Fn chroot
function call appeared in
.Bx 4.2 .
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: chroot.2,v 1.7 1995/02/27 12:32:12 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1983, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt CHROOT 2
	38	.Os BSD 4.2
	39	.Sh NAME
	40	.Nm chroot
	41	.Nd change root directory
	42	.Sh SYNOPSIS
	43	.Fd #include <unistd.h>
	44	.Ft int
	45	.Fn chroot "const char *dirname"
	46	.Sh DESCRIPTION
	47	.Fa Dirname
	48	is the address of the pathname of a directory, terminated by an ASCII NUL.
	49	.Fn Chroot
	50	causes
	51	.Fa dirname
	52	to become the root directory,
	53	that is, the starting point for path searches of pathnames
	54	beginning with
	55	.Ql / .
	56	.Pp
	57	In order for a directory to become the root directory
	58	a process must have execute (search) access for that directory.
	59	.Pp
	60	If the program is not currently running with an altered root directory,
	61	it should be noted that
	62	.Fn chroot
	63	has no effect on the process's current directory.
	64	.Pp
65	If the program is already running with an altered root directory, the
66	process's current directory is changed to the same new root directory.
67	This prevents the current directory from being further up the directory
68	tree than the altered root directory.
69	.Pp
70	This call is restricted to the super-user.
71	.Sh RETURN VALUES
72	Upon successful completion, a value of 0 is returned. Otherwise,
73	a value of -1 is returned and
74	.Va errno
75	is set to indicate an error.
76	.Sh ERRORS
77	.Fn Chroot
78	will fail and the root directory will be unchanged if:
79	.Bl -tag -width Er
80	.It Bq Er ENOTDIR
81	A component of the path name is not a directory.
82	.It Bq Er ENAMETOOLONG
83	A component of a pathname exceeded
84	.Dv {NAME_MAX}
85	characters, or an entire path name exceeded
86	.Dv {PATH_MAX}
87	characters.
88	.It Bq Er ENOENT
89	The named directory does not exist.
90	.It Bq Er EACCES
91	Search permission is denied for any component of the path name.
92	.It Bq Er ELOOP
93	Too many symbolic links were encountered in translating the pathname.
94	.It Bq Er EFAULT
95	.Fa Path
96	points outside the process's allocated address space.
97	.It Bq Er EIO
98	An I/O error occurred while reading from or writing to the file system.
99	.El
100	.Sh SEE ALSO
101	.Xr chdir 2
102	.Sh WARNINGS
103	There are ways for a root process to escape from the chroot jail.
104	.Sh HISTORY
105	The
106	.Fn chroot
107	function call appeared in
108	.Bx 4.2 .