samba-mirror/docs/Samba-HOWTO-Collection/VFS.xml

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<chapter id="VFS">
<chapterinfo>
	&author.jelmer;
	&author.jht;
	&author.tpot;
	<author><firstname>Simo</firstname><surname>Sorce</surname><contrib>original vfs_skel README</contrib></author>
	<author><firstname>Alexander</firstname><surname>Bokovoy</surname><contrib>original vfs_netatalk docs</contrib></author>
	<author><firstname>Stefan</firstname><surname>Metzmacher</surname><contrib>Update for multiple modules</contrib></author>
	<author><firstname>Ed</firstname><surname>Riddle</surname><contrib>original shadow_copy docs</contrib></author>
</chapterinfo>
<title>Stackable VFS modules</title>

<sect1>
<title>Features and Benefits</title>

<para>
Since Samba-3, there is support for stackable VFS (Virtual File System) modules. 
Samba passes each request to access the UNIX file system through the loaded VFS modules. 
This chapter covers all the modules that come with the Samba source and references to 
some external modules.
</para>


</sect1>

<sect1>
<title>Discussion</title>

<para>
If not supplied with your platform distribution binary Samba package you may have problems
compiling these modules, as shared libraries are compiled and linked in different ways
on different systems. They currently have been tested against GNU/Linux and IRIX.
</para>

<para>
To use the VFS modules, create a share similar to the one below. The
important parameter is the <smbconfoption><name>vfs objects</name></smbconfoption> parameter where
you can list one or more VFS modules by name. For example, to log all access 
to files and put deleted files in a recycle bin, see <link linkend="vfsrecyc">next configuration</link>:

<smbconfexample id="vfsrecyc">
	<title>smb.conf with VFS modules</title>
	<smbconfsection>[audit]</smbconfsection>
<smbconfoption><name>comment</name><value>Audited /data directory</value></smbconfoption>
<smbconfoption><name>path</name><value>/data</value></smbconfoption>
<smbconfoption><name>vfs objects</name><value>audit recycle</value></smbconfoption>
<smbconfoption><name>writeable</name><value>yes</value></smbconfoption>
<smbconfoption><name>browseable</name><value>yes</value></smbconfoption>
	</smbconfexample>
</para>

<para>
The modules are used in the order in which they are specified.
Let's say that you want to both have a virus scanner module and a recycle
bin module. It is wise to put the virus scanner module as the first one so
that it is the first that get run an may detect a virus immediately, before
any action is performed on that file.
<smbconfoption><name>vfs objects</name><value>vscan-clamav recycle</value></smbconfoption>
</para>

<para>
Samba will attempt to load modules from the <filename>/lib</filename> directory in the root directory of the
Samba installation (usually <filename>/usr/lib/samba/vfs</filename> or <filename>/usr/local/samba/lib/vfs
</filename>).
</para>

<para>
Some modules can be used twice for the same share.
This can be done using a configuration similar to the one shown in <link linkend="multimodule">the following example</link>.

<smbconfexample id="multimodule">
	<title>smb.conf with multiple VFS modules</title>
<smbconfsection>[test]</smbconfsection>
<smbconfoption><name>comment</name><value>VFS TEST</value></smbconfoption>
<smbconfoption><name>path</name><value>/data</value></smbconfoption>
<smbconfoption><name>writeable</name><value>yes</value></smbconfoption>
<smbconfoption><name>browseable</name><value>yes</value></smbconfoption>
<smbconfoption><name>vfs objects</name><value>example:example1 example example:test</value></smbconfoption>
<smbconfoption><name>example1: parameter</name><value>1</value></smbconfoption>
<smbconfoption><name>example:  parameter</name><value>5</value></smbconfoption>
<smbconfoption><name>test:	  parameter</name><value>7</value></smbconfoption>
</smbconfexample>
</para>

</sect1>

<sect1>
<title>Included Modules</title>

	<sect2>
	<title>audit</title>

		<para>
		A simple module to audit file access to the syslog
		facility. The following operations are logged:
		<itemizedlist>
			<listitem><para>share</para></listitem>
			<listitem><para>connect/disconnect</para></listitem>
			<listitem><para>directory opens/create/remove</para></listitem>
			<listitem><para>file open/close/rename/unlink/chmod</para></listitem>
		</itemizedlist>
		</para>

	</sect2>

	<sect2>
	<title>extd_audit</title>

		<para>
		This module is identical with the <command>audit</command> module above except
		that it sends audit logs to both syslog as well as the <command>smbd</command> log files. The 
		<smbconfoption><name>log level</name></smbconfoption> for this module is set in the &smb.conf; file. 
		</para>

		<para>
		Valid settings and the information that will be recorded are shown in <link linkend="xtdaudit">the next table</link>.
		</para>

		<table frame="all" id="xtdaudit">
			<title>Extended Auditing Log Information</title>
		<tgroup cols="2" align="center">
			<thead>
			<row><entry align="center">Log Level</entry><entry>Log Details - File and Directory Operations</entry></row>
			</thead>
			<tbody>
			<row><entry align="center">0</entry><entry align="left">Creation / Deletion</entry></row>
			<row><entry align="center">1</entry><entry align="left">Create / Delete / Rename / Permission Changes</entry></row>
			<row><entry align="center">2</entry><entry align="left">Create / Delete / Rename / Perm Change / Open / Close</entry></row>
			</tbody>
		</tgroup>
		</table>

	</sect2>

	<sect2 id="fakeperms">
	<title>fake_perms</title>

		<para>
		This module was created to allow Roaming Profile files and directories to be set (on the Samba server
		under UNIX) as read only. This module will, if installed on the Profiles share, report to the client
		that the Profile files and directories are writeable. This satisfies the client even though the files
		will never be overwritten as the client logs out or shuts down.
		</para>

	</sect2>

	<sect2>
	<title>recycle</title>

		<para>
		A Recycle Bin-like module. Where used, unlink calls will be intercepted and files moved
		to the recycle directory instead of being deleted. This gives the same effect as the
		<guiicon>Recycle Bin</guiicon> on Windows computers.
		</para>

		<para>
		The <guiicon>Recycle Bin</guiicon> will not appear in <application>Windows Explorer</application> views of the network file system
		(share) nor on any mapped drive. Instead, a directory called <filename>.recycle</filename> will be
		automatically created when the first file is deleted. Users can recover files from the 
		<filename>.recycle</filename> directory. If the <parameter>recycle:keeptree</parameter> has been
		specified, deleted files will be found in a path identical with that from which the file was deleted.
		</para>
		
		<para>Supported options for the <command>recycle</command> module are as follow:
		<variablelist>
			<varlistentry>
			<term>recycle:repository</term>
				<listitem><para>
				Relative path of the directory where deleted files should be moved.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:keeptree</term>
				<listitem><para>
				Specifies whether the directory structure should be kept or if the files in the directory that is being 
				deleted should be kept separately in the recycle bin.
				</para></listitem>
			</varlistentry>
			
			<varlistentry>
			<term>recycle:versions</term>
				<listitem><para>
				If this option is set, two files 
				with the same name that are deleted will both 
				be kept in the recycle bin. Newer deleted versions 
				of a file will be called <quote>Copy #x of <replaceable>filename</replaceable></quote>.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:touch</term>
				<listitem><para>
				Specifies whether a file's access date should be touched when the file is moved to the recycle bin.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:maxsize</term>
				<listitem><para>
				Files that are larger than the number of bytes specified by this parameter will not be put into the recycle bin.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:exclude</term>
				<listitem><para>
				List of files that should not be put into the recycle bin when deleted, but deleted in the regular way.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:exclude_dir</term>
				<listitem><para>
				Contains a list of directories. When files from these directories are
				deleted, they are not put into the
				recycle bin but are deleted in the
				regular way.
				</para></listitem>
			</varlistentry>

			<varlistentry>
			<term>recycle:noversions</term>
				<listitem><para>
				Specifies a list of paths (wildcards such as * and ? are supported) for which no versioning should be used. Only useful when <emphasis>recycle:versions</emphasis> is enabled.
				</para></listitem>
			</varlistentry>
		</variablelist>
		</para>

	</sect2>

	<sect2>
	<title>netatalk</title>

		<para>
		A netatalk module will ease co-existence of Samba and netatalk file sharing services.
		</para>

		<para>Advantages compared to the old netatalk module:
		<itemizedlist>
			<listitem><para>Does not care about creating .AppleDouble forks, just keeps them in sync.</para></listitem>
			<listitem><para>If a share in &smb.conf; does not contain .AppleDouble item in hide or veto list, it will be added automatically.</para></listitem>
		</itemizedlist>
		</para>

	</sect2>

    <sect2>
      <title>shadow_copy</title>
	<warning>
	<para>
	  <emphasis>THIS IS NOT A BACKUP, ARCHIVAL, OR VERSION CONTROL
	  SOLUTION!</emphasis></para>
	<para>
	  With Samba or Windows servers, shadow copy is designed to be
	  an end-user tool only.  It does not replace or enhance your
	  backup and archival solutions and should in no way be
	  considered as such.  Additionally, if you need version
	  control, implement a version control system.  You have been
	  warned.</para>
	</warning>
      <para>
	The shadow_copy module allows you to setup functionality that
	is similar to MS shadow copy services.  When setup properly,
	this module allows Microsoft shadow copy clients to browse
	"shadow copies" on samba shares.  You will need to install the
	shadow copy client.  You can get the MS shadow copy client
	<ulink noescape="1"
	url="http://www.microsoft.com/windowsserver2003/downloads/shadowcopyclient.mspx">here.</ulink>.
	Note the additional requirements for pre-Windows XP clients.
	I did not test this functionality with any pre-Windows XP
	clients.  You should be able to get more information about MS
	Shadow Copy <ulink noescape="1"
	url="http://www.microsoft.com/windowsserver2003/techinfo/overview/scr.mspx">from
	the Microsoft's site</ulink>.</para>
      <para>
	The shadow_copy VFS module requires some underlying file system
	setup with some sort of Logical Volume Manager (LVM) such as
	LVM1, LVM2, or EVMS.  Setting up LVM is beyond the scope of
	this document; however, we will outline the steps we took to
	test this functionality for <emphasis>example purposes
	only.</emphasis> You need to make sure the LVM implementation
	you choose to deploy is ready for production.  Make sure you
	do plenty of tests.</para>
      <para>
	Here are some common resources for LVM and EVMS:
	<itemizedlist>
	  <listitem>
	    <para><ulink noescape="1"
	    url="http://www.sistina.com/products_lvm_download.htm">Sistina's
	    LVM1 and LVM2</ulink></para>
	  </listitem>
	  <listitem>
	    <para><ulink url="http://evms.sourceforge.net/">Enterprise
	    Volume Management System (EVMS)</ulink></para>
	  </listitem>
	  <listitem>
	    <para><ulink url="http://tldp.org/HOWTO/LVM-HOWTO/">The LVM HOWTO</ulink></para>
	  </listitem>
	  <listitem>
	    <para>
	      See <ulink
	      url="http://www-106.ibm.com/developerworks/linux/library/l-lvm/">Learning
	      Linux LVM, Part 1</ulink> and <ulink
	      url="http://www-106.ibm.com/developerworks/library/l-lvm2.html">Learning
	      Linux LWM, Part 2</ulink> for Daniel Robbins' well
	      written a two part tutorial on Linux and LVM using LVM
	      source code and reiserfs.</para>
	  </listitem>
	</itemizedlist>
      </para>
      <sect3>
	<title>Shadow Copy Setup</title>
	<para>
	  At the time of this writing, not much testing has been done.
	  I tested the shadow copy VFS module with a specific scenario
	  which was not deployed in a production environment, but more
	  as a proof of concept.  The scenario involved a Samba 3 file
	  server on Debian Sarge with an XFS file system and LVM1.  I
	  do NOT recommend you use this as a solution without doing
	  your own due diligence with regard to all the components
	  presented here.  That said, following is an basic outline of
	  how I got things going.</para>
	<orderedlist>
	  <listitem>
	    <formalpara>
	      <title>Installed Operating System </title> 
	      <para>
		In my tests, I used <ulink
		url="http://www.debian.org/devel/debian-installer/">Debian
		Sarge</ulink> (i.e. testing) on an XFS file system.
		Setting up the OS is a bit beyond the scope of this
		document.  It is assumed that you have a working OS
		capable of running Samba.</para>
	    </formalpara>
	  </listitem>
	  <listitem>
	    <formalpara>
	      <title>Install &amp; Configure Samba</title>
	      <para>
		See the <link linkend="introduction">installation
		section</link> of this HOWTO for more detail on this.
		It doesn't matter if it is a Domain Controller or
		Member File Server, but it is assumed that you have a
		working Samba 3.0.3 or newer server running.</para>
	    </formalpara>
	  </listitem>
	  <listitem>
	    <formalpara>
	      <title>Install &amp; Configure LVM</title>
	      <para>
		Before you can make shadow copies available to the
		client, you have to create the shadow copies.  This is
		done by taking some sort of file system snapshot.
		Snapshots are a typical feature of Logical Volume
		Managers such as LVM, so we first need to have that
		setup.</para>
	    </formalpara>
	    <itemizedlist>
	      <para>
		The following is provided as an example and will be
		most helpful for Debian users.  Again, this was tested
		using the "testing" or "Sarge" distribution.</para>
	      <listitem>
		<para>
		  Install lvm10 and devfsd packages if you have not
		  done so already.  On Debian systems, you are warned
		  of the interaction of devfs and lvm1 which requires
		  the use of devfs filenames.  Running
		  <command>apt-get update &amp;&amp; apt-get install
		  lvm10 devfsd xfsprogs</command> should do the trick
		  for this example.</para>
	      </listitem>
	      <listitem>
		<para>
		  Now you need to create a volume.  You will need to
		  create a partition (or partitions) to add to your
		  volume.  Use your favorite partitioning tool
		  (e.g. Linux fdisk, cfdisk, etc.).  The partition
		  type should be set to 0x8e for "Linux LVM."  In this
		  example, we will use /dev/hdb1.</para>
		<para>
		  Once you have the Linux LVM partition (type 0x8e),
		  you can run a series of commands to create the LVM
		  volume.  You can use several disks and or
		  partitions, but we will use only one in this
		  example.  You may also need to load the kernel
		  module with something like <command>modprobe lvm-mod
		  </command> and set your system up to load it on
		  reboot by adding it to
		  (<filename>/etc/modules</filename>). </para>
	      </listitem>
	      <listitem>
		<para>
		  Create the physical volume with <command>pvcreate
		  /dev/hdb1</command></para>
	      </listitem>
	      <listitem>
		<para>
		  Create the volume group with and add /dev/hda1 to it
		  with <command>vgcreate shadowvol /dev/hdb1</command>
		  </para>
		<para>
		  You can use <command>vgdisplay</command> to review
		  information about the volume group.</para>
	      </listitem>
	      <listitem>
		<para>
		  Now you can create the logical volume with something
		  like <command>lvcreate -L400M -nsh_test
		  shadowvol</command></para>
		<para>
		  This creates the logical volume of 400MB's named
		  "sh_test" in the volume group we created called
		  shadowvol.  If everything is working so far, you
		  should see them in
		  <filename>/dev/shadowvol</filename>.</para>
	      </listitem>
	      <listitem>
		<para>
		  Now we should be ready to format the logical volume
		  we named sh_test with <command>mkfs.xfs
		  /dev/shadowvol/sh_test</command></para>
		<para>
		  You can format the logical volume with any file
		  system you choose, but make sure to use one that
		  allows you to take advantage of the additional
		  features of LVM such as freezing, resizing and
		  growing your file systems.</para>
		<para>
		  Now we have an LVM volume where we can play with the
		  shadow_copy VFS module.</para>
	      </listitem>
	      <listitem>
		<para>
		  Now we need to prepare the directory with something
		  like <command>mkdir -p /data/shadow_share</command>
		  or whatever you want to name your shadow copy
		  enabled Samba share.  Make sure you set the
		  permissions such that you can use it.  If in doubt,
		  use <command>chmod 777 /data/shadow_share</command>
		  and tighten the permissions once you get things
		  working.</para>
	      </listitem>
	      <listitem>
		<para>
		  Mount the LVM volume using something like
		  <command>mount /dev/shadowvol/sh_test
		  /data/shadow_share</command></para>
		<para>
		  You may also want to edit your
		  <filename>/etc/fstab</filename> so that this
		  partition mounts during the system boot.</para>
	      </listitem>
	    </itemizedlist>
	  </listitem>
	  <listitem>
	    <formalpara>
	      <title>Install &amp; Configure the shadow_copy VFS
	      Module</title>
	      <para>
		Finally we get to the actual shadow_copy VFS module.
		The shadow_copy VFS module should be available in
		Samba 3.0.3 and higher.  The smb.conf configuration is pretty
		standard.  Here is our example of a share configured
		with the shadow_copy VFS module:</para>
	    </formalpara>
	    <para>
	      <smbconfexample id="vfsshadow">
		<title>Share With shadow_copy VFS</title>
		<smbconfsection>[shadow_share]</smbconfsection>
		<smbconfoption><name>comment</name><value>Shadow Copy Enabled Share</value></smbconfoption>
		<smbconfoption><name>path</name><value>/data/shadow_share</value></smbconfoption>
		<smbconfoption><name>vfs objects</name><value>shadow_copy</value></smbconfoption>
		<smbconfoption><name>writeable</name><value>yes</value></smbconfoption>
		<smbconfoption><name>browseable</name><value>yes</value></smbconfoption>
	      </smbconfexample>
	    </para>
	  </listitem>
	  <listitem>
	    <formalpara>
	      <title>Create Snapshots and Make Them Available to shadow_copy.so</title> 
	      <para>
		Before you can browse the shadow copies, you must
		create them and mount them.  This will most likely be
		done with a script that runs as a cron job.  With this
		particular solution, the shadow_copy VFS module is
		used to browse LVM snapshots.  Those snapshots are not
		created by the module.  They are not made available by
		the module either.  This module allows the shadow copy
		enabled client to browse the snapshots you take and
		make available.</para>
	    </formalpara>
	    <para>
	      Here is a simple script used to create and mount the
	      snapshots:
	      <screen>
#!/bin/bash
# This is a test, this is only a test
SNAPNAME=`date +%Y.%m.%d-%H.%M.%S`
xfs_freeze -f /data/shadow_share/
lvcreate -L10M -s -n $SNAPNAME /dev/shadowvol/sh_test
xfs_freeze -u /data/shadow_share/
mkdir /data/shadow_share/@GMT-$SNAPNAME
mount /dev/shadowvol/$SNAPNAME /data/shadow_share/@GMT-$SNAPNAME -onouuid,ro
	      </screen>
	      Note that the script does not handle other things like
	      remounting snapshots on reboot.
	    </para>
	  </listitem>
	  <listitem>
	    <formalpara>
	      <title>Test From Client</title>
	      <para>
		To test, you will need to install the shadow copy
		client which you can obtain from the <ulink
		url="http://www.microsoft.com/windowsserver2003/downloads/shadowcopyclient.mspx">Microsoft
		web site.</ulink> I only tested this with an XP client
		so your results may vary with other pre-XP clients.
		Once installed, with your XP client you can
		right-click on specific files or in the empty space of
		the shadow_share and view the "properties".  If
		anything has changed, then you will see it on the
		"Previous Versions" tab of the properties
		window. </para>
	    </formalpara>
	  </listitem>
	</orderedlist>
      </sect3>
    </sect2>

</sect1>

<sect1>
<title>VFS Modules Available Elsewhere</title>

<para>
This section contains a listing of various other VFS modules that 
have been posted but do not currently reside in the Samba CVS 
tree for one reason or another (e.g., it is easy for the maintainer 
to have his or her own CVS tree).
</para>

<para>
No statements about the stability or functionality of any module
should be implied due to its presence here.
</para>

	<sect2>
	<title>DatabaseFS</title>

		<para>
		URL: <ulink noescape="1" url="http://www.css.tayloru.edu/~elorimer/databasefs/index.php">http://www.css.tayloru.edu/~elorimer/databasefs/index.php</ulink>
		</para>

		<para>By <ulink url="mailto:elorimer@css.tayloru.edu">Eric Lorimer.</ulink></para>

		<para>
		I have created a VFS module that implements a fairly complete read-only
		filesystem. It presents information from a database as a filesystem in
		a modular and generic way to allow different databases to be used
		(originally designed for organizing MP3s under directories such as
		<quote>Artists,</quote> <quote>Song Keywords,</quote> and so on. I have since easily
		applied it to a student
		roster database.) The directory structure is stored in the
		database itself and the module makes no assumptions about the database
		structure beyond the table it requires to run.
		</para>

		<para>
		Any feedback would be appreciated: comments, suggestions, patches,
		and so on. If nothing else, hopefully it might prove useful for someone
		else who wishes to create a virtual filesystem.
		</para>

	</sect2>

	<sect2>
	<title>vscan</title>

	<para>URL: <ulink noescape="1" url="http://www.openantivirus.org/">http://www.openantivirus.org/</ulink></para>

		<para>
		<filename>samba-vscan</filename> is a proof-of-concept module for Samba, which
		uses the VFS (virtual file system) features of Samba 2.2.x/3.0
		alphaX. Of course, Samba has to be compiled with VFS support. 
		<filename>samba-vscan</filename> supports various virus scanners and is maintained 
		by Rainer Link.
		</para>

	</sect2>
</sect1>

</chapter>