149 lines
5.0 KiB
Groff
149 lines
5.0 KiB
Groff
.\" $NetBSD: mount_umap.8,v 1.19 2005/09/11 23:40:43 wiz Exp $
|
|
.\"
|
|
.\" Copyright (c) 1992, 1993, 1994
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software donated to Berkeley by
|
|
.\" Jan-Simon Pendry and from John Heidemann of the UCLA Ficus project.
|
|
.\"
|
|
.\" 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. 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.
|
|
.\"
|
|
.\" @(#)mount_umap.8 8.4 (Berkeley) 5/1/95
|
|
.\"
|
|
.Dd March 6, 2001
|
|
.Dt MOUNT_UMAP 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm mount_umap
|
|
.Nd user and group ID remapping file system layer
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Fl o Ar options
|
|
.Fl g Ar gid-mapfile
|
|
.Fl u Ar uid-mapfile
|
|
.Ar target
|
|
.Ar mount-point
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
command is used to mount a sub-tree of an existing file system
|
|
that uses a different set of uids and gids than the local system.
|
|
Such a file system could be mounted from a remote site via NFS,
|
|
a local file system on removable media brought from some foreign
|
|
location that uses a different user/group database, or could be
|
|
a local file system for another operating system which does not
|
|
support Unix-style user/group IDs, or which uses a different
|
|
numbering scheme.
|
|
.Pp
|
|
Both
|
|
.Ar target
|
|
and
|
|
.Ar mount-point
|
|
are converted to absolute paths before use.
|
|
.Pp
|
|
The options are as follows:
|
|
.Bl -tag -width indent
|
|
.It Fl g Ar gid-mapfile
|
|
Use the group ID mapping specified in
|
|
.Ar gid-mapfile .
|
|
This flag is required.
|
|
.It Fl o
|
|
Options are specified with a
|
|
.Fl o
|
|
flag followed by a comma separated string of options.
|
|
See the
|
|
.Xr mount 8
|
|
man page for possible options and their meanings.
|
|
.It Fl u Ar uid-mapfile
|
|
Use the user ID mapping specified in
|
|
.Ar uid-mapfile .
|
|
This flag is required.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Nm
|
|
command uses a set of files provided by the user to make correspondences
|
|
between uids and gids in the sub-tree's original environment and
|
|
some other set of ids in the local environment.
|
|
For instance, user smith might have uid 1000 in the original environment,
|
|
while having uid 2000 in the local environment.
|
|
The
|
|
.Nm
|
|
command allows the subtree from smith's original environment to be
|
|
mapped in such a way that all files with owning uid 1000 look like
|
|
they are actually owned by uid 2000.
|
|
.Pp
|
|
.Em target
|
|
should be the current location of the sub-tree in the
|
|
local system's name space.
|
|
.Em mount-point
|
|
should be a directory
|
|
where the mapped subtree is to be placed.
|
|
.Em uid-mapfile
|
|
and
|
|
.Em gid-mapfile
|
|
describe the mappings to be made between identifiers.
|
|
.Pp
|
|
The format of the user and group ID mapping files is very simple.
|
|
The first line of the file is the total number of mappings present
|
|
in the file.
|
|
The remaining lines each consist of two numbers: the
|
|
ID in the mapped subtree and the ID in the original subtree.
|
|
.Pp
|
|
For example, to map uid 1000 in the original subtree to uid 2000
|
|
in the mapped subtree:
|
|
.Bd -unfilled -offset indent
|
|
1
|
|
2000 1000
|
|
.Ed
|
|
.Pp
|
|
For user IDs in the original subtree for which no mapping exists,
|
|
the user ID will be mapped to the user
|
|
.Dq nobody .
|
|
For group IDs in the original subtree for which no mapping exists,
|
|
the group ID will be mapped to the group
|
|
.Dq nobody .
|
|
.Pp
|
|
There is a limit of 64 user ID mappings and 16 group ID mappings.
|
|
.Pp
|
|
The mapfiles can be located anywhere in the file hierarchy, but they
|
|
must be owned by root, and they must be writable only by root.
|
|
.Nm
|
|
will refuse to map the sub-tree if the ownership or permissions on
|
|
these files are improper.
|
|
It will also report an error if the count
|
|
of mappings in the first line of the map files is not correct.
|
|
.Sh SEE ALSO
|
|
.Xr mount 8 ,
|
|
.Xr mount_null 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility first appeared in
|
|
.Bx 4.4 .
|
|
.Sh BUGS
|
|
The implementation is not very sophisticated.
|