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 thru 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 -to compile 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: - -

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 below. - -

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 file/s. The - loglevel for this module is set in the smb.conf file. -

- The logging information that will be written to the smbd log file is controlled by - the log level parameter in smb.conf. The - following information will be recorded: -

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 will 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. When used any unlink call - 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. -

Supported options: -

recycle:repository: Relative path of the directory where deleted files should be moved to
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 deleted in the regular way. -
recycle:noversions: Opposite of recycle:versions. If both options are specified, this one takes precedence.

netatalk

- A netatalk module, that will ease co-existence of samba and - netatalk file sharing services. -

Advantages compared to the old netatalk module: -

it doesn't care about creating of .AppleDouble forks, just keeps them in sync
if a share in smb.conf doesn't 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 don't 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 which 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," etc... I have since applied it to a student - roster database very easily). 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, - etc... 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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