Chapter 20. Stackable VFS modules

-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. -

Discussion

-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. -

-To use the VFS modules, create a share similar to the one below. The -important parameter is the vfs objects 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 . - -

Example 20.1. smb.conf with VFS modules

[audit]

comment = Audited /data directory

path = /data

vfs objects = audit recycle

writeable = yes

browseable = yes

-The modules are used in the order in which they are specified. -

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

-Some modules can be used twice for the same share. -This can be done using a configuration similar to the one shown in . - -

Example 20.2. smb.conf with multiple VFS modules

[test]

comment = VFS TEST

path = /data

writeable = yes

browseable = yes

vfs objects = example:example1 example example:test

example1: parameter = 1

example: parameter = 5

test: parameter = 7

Included Modules

audit

- A simple module to audit file access to the syslog - facility. The following operations are logged: -

share
connect/disconnect
directory opens/create/remove
file open/close/rename/unlink/chmod

extd_audit

- This module is identical with the audit module above except - that it sends audit logs to both syslog as well as the smbd log files. The - log level for this module is set in the smb.conf file. -

- Valid settings and the information that will be recorded are shown in . -

Table 20.1. Extended Auditing Log Information

Log Level	Log Details - File and Directory Operations
0	Creation / Deletion
1	Create / Delete / Rename / Permission Changes
2	Create / Delete / Rename / Perm Change / Open / Close

fake_perms

- 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 writable. This satisfies the client even though the files - will never be overwritten as the client logs out or shuts down. -

recycle

- 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 - Recycle Bin on Windows computers. -

- The Recycle Bin will not appear in Windows Explorer views of the network file system - (share) nor on any mapped drive. Instead, a directory called .recycle will be - automatically created when the first file is deleted. Users can recover files from the - .recycle directory. If the recycle:keeptree has been - specified, deleted files will be found in a path identical with that from which the file was deleted. -

Supported options for the recycle module are as follow: -

recycle:repository: - Relative path of the directory where deleted files should be moved. -
recycle:keeptree: - Specifies whether the directory structure should be kept or if the files in the directory that is being - deleted should be kept seperately in the recycle bin. -
recycle:versions: - 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 “Copy #x of filename”. -
recycle:touch: - Specifies whether a file's access date should be touched when the file is moved to the recycle bin. -
recycle:maxsize: - Files that are larger than the number of bytes specified by this parameter will not be put into the recycle bin. -
recycle:exclude: - List of files that should not be put into the recycle bin when deleted, but deleted in the regular way. -
recycle:exclude_dir: - 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. -
recycle:noversions: - Opposite of recycle:versions. If both options are specified, this one takes precedence. -

netatalk

- A netatalk module will ease co-existence of Samba and netatalk file sharing services. -

Advantages compared to the old netatalk module: -

Does not care about creating .AppleDouble forks, just keeps them in sync.
If a share in smb.conf does not contain .AppleDouble item in hide or veto list, it will be added automatically.

VFS Modules Available Elsewhere

-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). -

-No statements about the stability or functionality of any module -should be implied due to its presence here. -

DatabaseFS

- URL: http://www.css.tayloru.edu/~elorimer/databasefs/index.php -

By Eric Lorimer.

- 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 - “Artists,” “Song Keywords,” 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. -

- 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. -

vscan

URL: http://www.openantivirus.org/

- samba-vscan 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. - samba-vscan supports various virus scanners and is maintained - by Rainer Link. -

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