5c37a0ec6d
o Update extattrctl.c to default new attributes to readable and writable only by the kernel and root user. Previously the default was to allow the file owner to directory view and manipulate the attributes, which is probably an inappropriate default.
174 lines
5.3 KiB
Groff
174 lines
5.3 KiB
Groff
.\"-
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.\" Copyright (c) 2000 Robert N. M. Watson
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.\" 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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd March 30, 2000
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.Dt EXTATTRCTL 8
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.Os FreeBSD 5.0
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.Sh NAME
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.Nm extattrctl
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.Nd Manage FFS extended attributes
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.Sh SYNOPSIS
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.Nm extattrctl
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.Cm start
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.Ar path
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.Nm extattrctl
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.Cm stop
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.Ar path
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.Nm extattrctl
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.Cm initattr
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.Ar attrsize
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.Ar attrfile
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.Nm extattrctl
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.Cm enable
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.Ar path
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.Ar attrname
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.Ar attrfile
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.Nm extattrctl
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.Cm disable
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.Ar path
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.Ar attrname
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.Sh DESCRIPTION
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.Nm
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is the management utility for extended attributes over the FFS file system.
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.Nm
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allows the starting and stopping of extended attributes on a file system,
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as well as initialization of attribute backing files, and enabling and
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disabling of specific extended attributes on a file system.
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.Pp
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The first argument on the command line indicates the operation to be
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performend. Operation must be one of the following:
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.Bl -tag -width indent
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.It Cm start Ar path
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Start extended attribute support on the file system named using
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.Ar path .
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The file system must be an FFS file system, and the FFS_EXTATTR kernel
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option must have been enabled.
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.It Cm stop Ar path
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Stop extended attribute support on the file system named using
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.Ar path .
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Extended attribute support must previously have been started.
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.It Xo
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.Cm initattr
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.Op Fl p Ar path
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.Op Fl r Op Ar kroa
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.Op Fl w Op Ar kroa
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.Ar attrsize attrfile
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.Xc
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Create and initialize a file to use as an attribute backing file.
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You must specify a maximum per-inode size for the attribute in bytes in
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.Ar attrsize ,
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as well as the file where the attribute will be stored, using
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.Ar attrfile .
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.Pp
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The
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.Fl p Ar path
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argument may be used to preallocate space for all attributes rather than
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relying on sparse files to conserve space.
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This has the advantage of guaranteeing that space will be available
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for attributes when they are written, preventing low disk space conditions
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from denying attribute service.
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.Pp
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The
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.Fl r
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and
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.Fl w
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options can be used to set the read and write permissions on the named
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attribute, respectively.
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There are four levels possible for both read and write:
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.Dq k
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limits reading or writing to the kernel,
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.Dq r
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limits activities to root,
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.Dq o
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limits activities to root and the owner of the file having the attribute
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read or written, and
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.Dq q
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allows any user to perform the attribute operation.
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The default is to limit activities to the root user, or
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.Dq r
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.
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.Pp
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This file should not exist before running
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.Cm initattr.
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.It Cm enable Ar path Ar attrname Ar attrfile
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Enable an attribute named
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.Ar attrname
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on the file system identified using
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.Ar path ,
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and backed by initialized attribute file
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.Ar attrfile .
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The backing file must have been initialized using
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.Cm initattr
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before its first use.
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Attributes must have been started on the file system prior to the
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enabling of any attributes.
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.It Cm disable Ar path Ar attrname
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Disable the attributed named
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.Ar attrname
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on the file system identified by
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.Ar path .
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The file system must have attributes started on it, and the attribute
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most have been enabled using
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.Cm enable .
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.Sh EXAMPLES
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.Pp
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.Dl extattrctl start /
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.Pp
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Start extended attributes on the root file system.
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.Pp
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.Dl extattrctl initattr 17 /.attribute/md5
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.Pp
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Create an attribute backing file in /.attribute/md5, and set the maximum
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size of each attribute to 17 bytes. Sparse files are used for storing the
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attributes, and the default permissions limiting access to the root user
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are implied.
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.Pp
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.Dl extattrctl enable / md5 /.attribute/md5
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.Pp
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Enable an attribute named md5 on the root file system, backed from the file
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/.attribute/md5.
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.Pp
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.Dl extattrctl disable / md5
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.Pp
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Disable the attribute named md5 on the root file system.
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.Pp
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.Dl extattrctl stop /
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.Pp
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Stop extended attributes on the root file system.
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.Sh SEE ALSO
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.Xr getextattr 8 ,
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.Xr setextattr 8 ,
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.Xr extattr 9
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.Sh HISTORY
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Extended attribute support was developed as part of the TrustedBSD Project,
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and introduced in
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.Fx 5.0 .
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It was developed to support security extensions requiring additional labels
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to be associated with each file or directory.
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.Sh AUTHORS
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Robert N M Watson
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