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Linux内核自带的cifs模块

The CIFS VFS support for Linux supports many advanced network filesystem 
features such as hierarchical dfs like namespace, hardlinks, locking and more.  
It was designed to comply with the SNIA CIFS Technical Reference (which 
supersedes the 1992 X/Open SMB Standard) as well as to perform best practice 
practical interoperability with Windows 2000, Windows XP, Samba and equivalent 
servers.  

For questions or bug reports please contact:
    [e-mail] ([e-mail]) 

Build instructions:
==================
For Linux 2.4:
1) Get the kernel source (e.g.from http://www.kernel.org)
and download the cifs vfs source (see the project page
at http://us1.samba.org/samba/Linux_CIFS_client.html)
and change directory into the top of the kernel directory
then patch the kernel (e.g. "patch -p1 < cifs_24.patch") 
to add the cifs vfs to your kernel configure options if
it has not already been added (e.g. current SuSE and UL
users do not need to apply the cifs_24.patch since the cifs vfs is
already in the kernel configure menu) and then
mkdir linux/fs/cifs and then copy the current cifs vfs files from
the cifs download to your kernel build directory e.g.

	cp <cifs_download_dir>/fs/cifs/* to <kernel_download_dir>/fs/cifs
	
2) make menuconfig (or make xconfig)
3) select cifs from within the network filesystem choices
4) save and exit
5) make dep
6) make modules (or "make" if CIFS VFS not to be built as a module)

For Linux 2.6:
1) Download the kernel (e.g. from http://www.kernel.org)
and change directory into the top of the kernel directory tree
(e.g. /usr/src/linux-2.5.73)
2) make menuconfig (or make xconfig)
3) select cifs from within the network filesystem choices
4) save and exit
5) make


Installation instructions:
=========================
If you have built the CIFS vfs as module (successfully) simply
type "make modules_install" (or if you prefer, manually copy the file to
the modules directory e.g. /lib/modules/2.4.10-4GB/kernel/fs/cifs/cifs.o).

If you have built the CIFS vfs into the kernel itself, follow the instructions
for your distribution on how to install a new kernel (usually you
would simply type "make install").

If you do not have the utility mount.cifs (in the Samba 3.0 source tree and on 
the CIFS VFS web site) copy it to the same directory in which mount.smbfs and 
similar files reside (usually /sbin).  Although the helper software is not  
required, mount.cifs is recommended.  Eventually the Samba 3.0 utility program 
"net" may also be helpful since it may someday provide easier mount syntax for
users who are used to Windows e.g.  net use <mount point> <UNC name or cifs URL>
Note that running the Winbind pam/nss module (logon service) on all of your
Linux clients is useful in mapping Uids and Gids consistently across the
domain to the proper network user.  The mount.cifs mount helper can be
trivially built from Samba 3.0 or later source e.g. by executing:

	gcc samba/source/client/mount.cifs.c -o mount.cifs

If cifs is built as a module, then the size and number of network buffers
and maximum number of simultaneous requests to one server can be configured.
Changing these from their defaults is not recommended. By executing modinfo
	modinfo kernel/fs/cifs/cifs.ko
on kernel/fs/cifs/cifs.ko the list of configuration changes that can be made
at module initialization time (by running insmod cifs.ko) can be seen.

Allowing User Mounts
====================
To permit users to mount and unmount over directories they own is possible
with the cifs vfs.  A way to enable such mounting is to mark the mount.cifs
utility as suid (e.g. "chmod +s /sbin/mount.cifs). To enable users to 
umount shares they mount requires
1) mount.cifs version 1.4 or later
2) an entry for the share in /etc/fstab indicating that a user may
unmount it e.g.
//server/usersharename  /mnt/username cifs user 0 0

Note that when the mount.cifs utility is run suid (allowing user mounts), 
in order to reduce risks, the "nosuid" mount flag is passed in on mount to
disallow execution of an suid program mounted on the remote target.
When mount is executed as root, nosuid is not passed in by default,
and execution of suid programs on the remote target would be enabled
by default. This can be changed, as with nfs and other filesystems, 
by simply specifying "nosuid" among the mount options. For user mounts 
though to be able to pass the suid flag to mount requires rebuilding 
mount.cifs with the following flag: 
 
        gcc samba/source/client/mount.cifs.c -DCIFS_ALLOW_USR_SUID -o mount.cifs

There is a corresponding manual page for cifs mounting in the Samba 3.0 and
later source tree in docs/manpages/mount.cifs.8 

Allowing User Unmounts
======================
To permit users to ummount directories that they have user mounted (see above),
the utility umount.cifs may be used.  It may be invoked directly, or if 
umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
(at least for most versions of the umount utility) for umount of cifs
mounts, unless umount is invoked with -i (which will avoid invoking a umount
helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
as suid (e.g. "chmod +s /sbin/umount.cifs") or equivalent (some distributions
allow adding entries to a file to the /etc/permissions file to achieve the
equivalent suid effect).  For this utility to succeed the target path
must be a cifs mount, and the uid of the current user must match the uid
of the user who mounted the resource.

Also note that the customary way of allowing user mounts and unmounts is 
(instead of using mount.cifs and unmount.cifs as suid) to add a line
to the file /etc/fstab for each //server/share you wish to mount, but
this can become unwieldy when potential mount targets include many
or  unpredictable UNC names.

Samba Considerations 
==================== 
To get the maximum benefit from the CIFS VFS, we recommend using a server that 
supports the SNIA CIFS Unix Extensions standard (e.g.  Samba 2.2.5 or later or 
Samba 3.0) but the CIFS vfs works fine with a wide variety of CIFS servers.  
Note that uid, gid and file permissions will display default values if you do 
not have a server that supports the Unix extensions for CIFS (such as Samba 
2.2.5 or later).  To enable the Unix CIFS Extensions in the Samba server, add 
the line: 

	unix extensions = yes
	
to your smb.conf file on the server.  Note that the following smb.conf settings 
are also useful (on the Samba server) when the majority of clients are Unix or 
Linux: 

	case sensitive = yes
	delete readonly = yes 
	ea support = yes

Note that server ea support is required for supporting xattrs from the Linux
cifs client, and that EA support is present in later versions of Samba (e.g. 
3.0.6 and later (also EA support works in all versions of Windows, at least to
shares on NTFS filesystems).  Extended Attribute (xattr) support is an optional
feature of most Linux filesystems which may require enabling via
make menuconfig. Client support for extended attributes (user xattr) can be
disabled on a per-mount basis by specifying "nouser_xattr" on mount.

The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
version 3.10 and later.  Setting POSIX ACLs requires enabling both XATTR and 
then POSIX support in the CIFS configuration options when building the cifs
module.  POSIX ACL support can be disabled on a per mount basic by specifying
"noacl" on mount.
 
Some administrators may want to change Samba's smb.conf "map archive" and 
"create mask" parameters from the default.  Unless the create mask is changed
newly created files can end up with an unnecessarily restrictive default mode,
which may not be what you want, although if the CIFS Unix extensions are
enabled on the server and client, subsequent setattr calls (e.g. chmod) can
fix the mode.  Note that creating special devices (mknod) remotely 
may require specifying a mkdev function to Samba if you are not using 
Samba 3.0.6 or later.  For more information on these see the manual pages
("man smb.conf") on the Samba server system.  Note that the cifs vfs,
unlike the smbfs vfs, does not read the smb.conf on the client system 
(the few optional settings are passed in on mount via -o parameters instead).  
Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
open files (required for strict POSIX compliance).  Windows Servers already 
supported this feature. Samba server does not allow symlinks that refer to files
outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
files with absolute paths (ie beginning with slash) such as:
	 ln -s /mnt/foo bar
would be forbidden. Samba 3.0.6 server or later includes the ability to create 
such symlinks safely by converting unsafe symlinks (ie symlinks to server 
files that are outside of the share) to a samba specific format on the server
that is ignored by local server applications and non-cifs clients and that will
not be traversed by the Samba server).  This is opaque to the Linux client
application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
later, but only for remote clients using the CIFS Unix extensions, and will
be invisbile to Windows clients and typically will not affect local
applications running on the same server as Samba.  

Use instructions:
================
Once the CIFS VFS support is built into the kernel or installed as a module 
(cifs.o), you can use mount syntax like the following to access Samba or Windows 
servers: 

  mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword

Before -o the option -v may be specified to make the mount.cifs
mount helper display the mount steps more verbosely.  
After -o the following commonly used cifs vfs specific options
are supported:

  user=<username>
  pass=<password>
  domain=<domain name>
  
Other cifs mount options are described below.  Use of TCP names (in addition to
ip addresses) is available if the mount helper (mount.cifs) is installed. If
you do not trust the server to which are mounted, or if you do not have
cifs signing enabled (and the physical network is insecure), consider use
of the standard mount options "noexec" and "nosuid" to reduce the risk of 
running an altered binary on your local system (downloaded from a hostile server
or altered by a hostile router).

Although mounting using format corresponding to the CIFS URL specification is
not possible in mount.cifs yet, it is possible to use an alternate format
for the server and sharename (which is somewhat similar to NFS style mount
syntax) instead of the more widely used UNC format (i.e. \\server\share):
  mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd

When using the mount helper mount.cifs, passwords may be specified via alternate