140 lines
4.4 KiB
Groff
140 lines
4.4 KiB
Groff
.\" $NetBSD: chroot.2,v 1.13 2001/04/18 08:28:11 kleink Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd April 18, 2001
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.Dt CHROOT 2
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.Os
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.Sh NAME
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.Nm chroot
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.Nd change root directory
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <unistd.h>
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.Ft int
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.Fn chroot "const char *dirname"
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.Ft int
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.Fn fchroot "int fd"
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.Sh DESCRIPTION
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.Fa dirname
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is the address of the pathname of a directory, terminated by an ASCII NUL.
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.Fn chroot
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causes
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.Fa dirname
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to become the root directory,
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that is, the starting point for path searches of pathnames
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beginning with
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.Ql / .
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.Pp
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In order for a directory to become the root directory
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a process must have execute (search) access for that directory.
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.Pp
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If the current working directory is not at or under the new root
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directory, it is silently set to the new root directory.
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It should be noted that, on most other systems,
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.Fn chroot
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has no effect on the process's current directory.
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.Pp
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This call is restricted to the super-user.
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.Pp
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The
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.Fn fchroot
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function performs the same operation on an open directory file
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known by the file descriptor
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.Fa fd .
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.Sh RETURN VALUES
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Upon successful completion, a value of 0 is returned. Otherwise,
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a value of -1 is returned and
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.Va errno
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is set to indicate an error.
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.Sh ERRORS
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.Fn chroot
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will fail and the root directory will be unchanged if:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path name is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Dv {NAME_MAX}
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characters, or an entire path name exceeded
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.Dv {PATH_MAX}
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characters.
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.It Bq Er ENOENT
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The named directory does not exist.
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.It Bq Er EACCES
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Search permission is denied for any component of the path name.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EFAULT
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.Fa dirname
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points outside the process's allocated address space.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Pp
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.Fn fchroot
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will fail and the root directory will be unchanged if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Search permission is denied for the directory referenced
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by the file descriptor.
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.It Bq Er EBADF
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The argument
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.Fa fd
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is not a valid file descriptor.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.It Bq Er ENOTDIR
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The argument
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.Fa fd
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does not reference a directory.
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.El
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.Sh SEE ALSO
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.Xr chdir 2
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.Sh HISTORY
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The
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.Fn chroot
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function call appeared in
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.Bx 4.2 .
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Working directory handling was changed in
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.Nx 1.4
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to prevent one way a process could use a second
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.Fn chroot
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call to a different directory to "escape" from the restricted subtree.
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The
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.Fn fchroot
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function appeared in
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.Nx 1.4 .
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