[samba.git] / 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">Make Directory, Remove Directory, Unlink</entry></row>
                        <row><entry align="center">1</entry><entry align="left">Open Directory, Rename File, Change Permissions/ACLs</entry></row>
                        <row><entry align="center">2</entry><entry align="left">Open &amp; Close File</entry></row>
                        <row><entry align="center">10</entry><entry align="left">Maximum Debug Level</entry></row>
                        </tbody>
                </tgroup>
                </table>

                <sect3>
                <title>Configuration of Auditing</title>

                <para>
                This auditing tool is more felxible than most people readily will recognize. There are a number of ways
                by which useful logging information can be recorded.
                </para>

                <itemizedlist>
                        <listitem><para>Syslog can be used to record all transaction. This can be disabled by setting
                                        in the &smb.conf; file <parameter>syslog = 0</parameter>.</para></listitem>
                        <listitem><para>Logging can take place to the default log file (<filename>log.smbd</filename>)
                                        for all loaded VFS modules just by setting in the &smb.conf; file
                                        <parameter>log level = 0 vfs:x</parameter>, where x is the log level.
                                        This will disable general logging while activating all logging of VFS
                                        module activity at the log level specified.</para></listitem>
                        <listitem><para>Detailed logging can be obtained per user, per client machine, etc.
                                        This requires the above together with the creative use of the
                                        <parameter>log file</parameter> settings.</para>
                                        <para>An example of detailed per-user and per-machine logging can
                                        be obtained by setting 
                                        <smbconfoption><name>log level</name>
                                        <value>/var/log/samba/%U.%m.log</value></smbconfoption>.
                                        </para></listitem>
                </itemizedlist>

                <para>
                Auditing information often must be preserved for a long time. So that the log files do not get rotated
                it is essential that the <smbconfoption><name>max log size</name><value>0</value></smbconfoption> be set
                in the &smb.conf; file.
                </para>

                </sect3>

        </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/projects.php#samba-vscan">http://www.openantivirus.org/projects.php#samba-vscan</ulink></para>

                <para>
                samba-vscan is a proof-of-concept module for Samba, which
                provides on-access anti-virus support for files shared using 
                Samba.
                samba-vscan supports various virus scanners and is maintained 
                by Rainer Link.
                </para>

        </sect2>
</sect1>

</chapter>