1.\" $NetBSD: extattrctl.8,v 1.5 2011/06/17 18:20:40 wiz Exp $ 2.\" 3.\" Copyright (c) 2000-2001 Robert N. M. Watson 4.\" All rights reserved. 5.\" 6.\" This software was developed by Robert Watson for the TrustedBSD Project. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" $FreeBSD: src/usr.sbin/extattrctl/extattrctl.8,v 1.24 2005/02/09 18:04:40 ru Exp $ 30.\" 31.\" Developed by the TrustedBSD Project. 32.\" Support for file system extended attribute. 33.\" 34.Dd June 17, 2011 35.Dt EXTATTRCTL 8 36.Os 37.Sh NAME 38.Nm extattrctl 39.Nd manage UFS1 extended attributes 40.Sh SYNOPSIS 41.Nm 42.Cm start 43.Ar path 44.Nm 45.Cm stop 46.Ar path 47.Nm 48.Cm initattr 49.Op Fl f 50.Op Fl p Ar path 51.Ar attrsize 52.Ar attrfile 53.Nm 54.Cm showattr 55.Ar attrfile 56.Nm 57.Cm enable 58.Ar path 59.Ar attrnamespace 60.Ar attrname 61.Ar attrfile 62.Nm 63.Cm disable 64.Ar path 65.Ar attrnamespace 66.Ar attrname 67.Sh DESCRIPTION 68The 69.Nm 70utility 71is the management utility for extended attributes over the UFS1 file system. 72It allows the starting and stopping of extended attributes on a file system, 73as well as initialization of attribute backing files, and enabling and 74disabling of specific extended attributes on a file system. 75.Pp 76The first argument on the command line indicates the operation to be 77performed. 78Operation must be one of the following: 79.Bl -tag -width indent 80.It Cm start Ar path 81Start extended attribute support on the file system named using 82.Ar path . 83The file system must be a UFS1 file system, and the 84.Dv UFS_EXTATTR 85kernel option must have been enabled. 86If 87.Pa .attribute/user 88and 89.Pa .attribute/system 90exist at the filesystem root, extended attributes backed by files 91in these directories will be automatically enabled. 92Note that extended attributes can be automatically started at mount 93time by using the 94.Cm -o extattr 95option to 96.Xr mount 8 . 97.It Cm stop Ar path 98Stop extended attribute support on the file system named using 99.Ar path . 100Extended attribute support must previously have been started. 101.It Cm initattr Oo Fl f Oc Oo Fl p Ar path Oc Ar attrsize attrfile 102Create and initialize a file to use as an attribute backing file. 103You must specify a maximum per-inode size for the attribute in bytes in 104.Ar attrsize , 105as well as the file where the attribute will be stored, using 106.Ar attrfile . 107.Pp 108The 109.Fl f 110argument may be used to indicate that it is alright to overwrite an 111existing attribute backing file; otherwise, if the target file exists, 112an error will be returned. 113.Pp 114The 115.Fl p Ar path 116argument may be used to preallocate space for all attributes rather than 117relying on sparse files to conserve space. 118This has the advantage of guaranteeing that space will be available 119for attributes when they are written, preventing low disk space conditions 120from denying attribute service. 121.Pp 122This file should not exist before running 123.Cm initattr . 124.Pp 125When a user attempts to set a 126.Dq user 127or 128.Dq system 129extended attribute that lacks a backing file, 130the kernel will attempt to automatically create it, provided 131.Pa .attribute/user 132or 133.Pa .attribute/system 134exist and are writable by the requesting user. 135.It Cm showattr Ar attrfile 136Show the attribute header values in the attribute file named by 137.Ar attrfile . 138.It Cm enable Ar path attrnamespace attrname attrfile 139Enable an attribute named 140.Ar attrname 141in the namespace 142.Ar attrnamespace 143on the file system identified using 144.Ar path , 145and backed by initialized attribute file 146.Ar attrfile . 147Available namespaces are 148.Dq user 149and 150.Dq system . 151The backing file must have been initialized using 152.Cm initattr 153before its first use. 154Attributes must have been started on the file system prior to the 155enabling of any attributes. 156.It Cm disable Ar path attrnamespace attrname 157Disable the attributed named 158.Ar attrname 159in namespace 160.Ar attrnamespace 161on the file system identified by 162.Ar path . 163Available namespaces are 164.Dq user 165and 166.Dq system . 167The file system must have attributes started on it, and the attribute 168most have been enabled using 169.Cm enable . 170.El 171.Sh EXAMPLES 172.Dl extattrctl start / 173.Pp 174Start extended attributes on the root file system. 175.Pp 176.Dl extattrctl initattr 17 /.attribute/system/md5 177.Pp 178Create an attribute backing file in 179.Pa /.attribute/system/md5 , 180and set the maximum size of each attribute to 17 bytes, with a 181sparse file used for storing the attributes. 182.Pp 183.Dl extattrctl enable / system md5 /.attribute/system/md5 184.Pp 185Enable an attribute named md5 on the root file system, backed from the file 186.Pa /.attribute/system/md5 . 187.Pp 188.Dl extattrctl disable / md5 189.Pp 190Disable the attribute named md5 on the root file system. 191.Pp 192.Dl extattrctl stop / 193.Pp 194Stop extended attributes on the root file system. 195.Sh SEE ALSO 196.Xr getextattr 1 , 197.Xr extattr_get_file 2 , 198.\" .Xr ffs 7 , 199.Xr extattr 9 200.Sh HISTORY 201Extended attribute support was developed as part of the TrustedBSD 202Project, and introduced in 203.Fx 5.0 204and 205.Nx 4.0 . 206It was developed to support security extensions requiring additional 207labels to be associated with each file or directory. 208Backing file autocreation was added in 209.Nx 6.0 . 210.Sh AUTHORS 211.An Robert N M Watson 212.Sh BUGS 213.Nm 214works only on UFS1 file systems. 215The kernel support for extended attribute backing files and this 216control program should be generalized for any file system that 217lacks native extended attribute support. 218