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Linus Torvalds1da177e2005-04-16 15:20:36 -07001The CIFS VFS support for Linux supports many advanced network filesystem
Uwe Kleine-König1b3c3712007-02-17 19:23:03 +01002features such as hierarchical dfs like namespace, hardlinks, locking and more.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003It was designed to comply with the SNIA CIFS Technical Reference (which
4supersedes the 1992 X/Open SMB Standard) as well as to perform best practice
5practical interoperability with Windows 2000, Windows XP, Samba and equivalent
Steve French675c4672008-04-17 23:41:01 +00006servers. This code was developed in participation with the Protocol Freedom
7Information Foundation.
8
9Please see
10 http://protocolfreedom.org/ and
11 http://samba.org/samba/PFIF/
12for more details.
13
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
15For questions or bug reports please contact:
16 sfrench@samba.org (sfrench@us.ibm.com)
17
18Build instructions:
19==================
20For Linux 2.4:
211) Get the kernel source (e.g.from http://www.kernel.org)
22and download the cifs vfs source (see the project page
23at http://us1.samba.org/samba/Linux_CIFS_client.html)
24and change directory into the top of the kernel directory
25then patch the kernel (e.g. "patch -p1 < cifs_24.patch")
26to add the cifs vfs to your kernel configure options if
27it has not already been added (e.g. current SuSE and UL
28users do not need to apply the cifs_24.patch since the cifs vfs is
29already in the kernel configure menu) and then
30mkdir linux/fs/cifs and then copy the current cifs vfs files from
31the cifs download to your kernel build directory e.g.
32
33 cp <cifs_download_dir>/fs/cifs/* to <kernel_download_dir>/fs/cifs
34
352) make menuconfig (or make xconfig)
363) select cifs from within the network filesystem choices
374) save and exit
385) make dep
396) make modules (or "make" if CIFS VFS not to be built as a module)
40
41For Linux 2.6:
Adrian Bunkdfc1e142005-05-05 16:15:51 -0700421) Download the kernel (e.g. from http://www.kernel.org)
43and change directory into the top of the kernel directory tree
44(e.g. /usr/src/linux-2.5.73)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452) make menuconfig (or make xconfig)
463) select cifs from within the network filesystem choices
474) save and exit
485) make
49
50
51Installation instructions:
52=========================
53If you have built the CIFS vfs as module (successfully) simply
54type "make modules_install" (or if you prefer, manually copy the file to
55the modules directory e.g. /lib/modules/2.4.10-4GB/kernel/fs/cifs/cifs.o).
56
57If you have built the CIFS vfs into the kernel itself, follow the instructions
58for your distribution on how to install a new kernel (usually you
59would simply type "make install").
60
61If you do not have the utility mount.cifs (in the Samba 3.0 source tree and on
62the CIFS VFS web site) copy it to the same directory in which mount.smbfs and
63similar files reside (usually /sbin). Although the helper software is not
64required, mount.cifs is recommended. Eventually the Samba 3.0 utility program
65"net" may also be helpful since it may someday provide easier mount syntax for
Steve Frenchf6d09982008-01-08 23:18:22 +000066users who are used to Windows e.g.
67 net use <mount point> <UNC name or cifs URL>
Linus Torvalds1da177e2005-04-16 15:20:36 -070068Note that running the Winbind pam/nss module (logon service) on all of your
69Linux clients is useful in mapping Uids and Gids consistently across the
70domain to the proper network user. The mount.cifs mount helper can be
71trivially built from Samba 3.0 or later source e.g. by executing:
72
73 gcc samba/source/client/mount.cifs.c -o mount.cifs
74
75If cifs is built as a module, then the size and number of network buffers
76and maximum number of simultaneous requests to one server can be configured.
77Changing these from their defaults is not recommended. By executing modinfo
78 modinfo kernel/fs/cifs/cifs.ko
79on kernel/fs/cifs/cifs.ko the list of configuration changes that can be made
80at module initialization time (by running insmod cifs.ko) can be seen.
81
82Allowing User Mounts
83====================
84To permit users to mount and unmount over directories they own is possible
85with the cifs vfs. A way to enable such mounting is to mark the mount.cifs
Steve French099a58f2005-04-28 22:41:07 -070086utility as suid (e.g. "chmod +s /sbin/mount.cifs). To enable users to
Linus Torvalds1da177e2005-04-16 15:20:36 -070087umount shares they mount requires
881) mount.cifs version 1.4 or later
892) an entry for the share in /etc/fstab indicating that a user may
90unmount it e.g.
91//server/usersharename /mnt/username cifs user 0 0
92
93Note that when the mount.cifs utility is run suid (allowing user mounts),
94in order to reduce risks, the "nosuid" mount flag is passed in on mount to
95disallow execution of an suid program mounted on the remote target.
96When mount is executed as root, nosuid is not passed in by default,
97and execution of suid programs on the remote target would be enabled
98by default. This can be changed, as with nfs and other filesystems,
99by simply specifying "nosuid" among the mount options. For user mounts
100though to be able to pass the suid flag to mount requires rebuilding
101mount.cifs with the following flag:
102
103 gcc samba/source/client/mount.cifs.c -DCIFS_ALLOW_USR_SUID -o mount.cifs
104
105There is a corresponding manual page for cifs mounting in the Samba 3.0 and
106later source tree in docs/manpages/mount.cifs.8
107
Steve French099a58f2005-04-28 22:41:07 -0700108Allowing User Unmounts
109======================
110To permit users to ummount directories that they have user mounted (see above),
111the utility umount.cifs may be used. It may be invoked directly, or if
Steve French0cb766a2005-04-28 22:41:11 -0700112umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
Steve French099a58f2005-04-28 22:41:07 -0700113(at least for most versions of the umount utility) for umount of cifs
Steve French0cb766a2005-04-28 22:41:11 -0700114mounts, unless umount is invoked with -i (which will avoid invoking a umount
115helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
116as suid (e.g. "chmod +s /sbin/umount.cifs") or equivalent (some distributions
117allow adding entries to a file to the /etc/permissions file to achieve the
118equivalent suid effect). For this utility to succeed the target path
119must be a cifs mount, and the uid of the current user must match the uid
120of the user who mounted the resource.
Steve French099a58f2005-04-28 22:41:07 -0700121
122Also note that the customary way of allowing user mounts and unmounts is
123(instead of using mount.cifs and unmount.cifs as suid) to add a line
124to the file /etc/fstab for each //server/share you wish to mount, but
125this can become unwieldy when potential mount targets include many
126or unpredictable UNC names.
127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128Samba Considerations
129====================
130To get the maximum benefit from the CIFS VFS, we recommend using a server that
131supports the SNIA CIFS Unix Extensions standard (e.g. Samba 2.2.5 or later or
132Samba 3.0) but the CIFS vfs works fine with a wide variety of CIFS servers.
133Note that uid, gid and file permissions will display default values if you do
134not have a server that supports the Unix extensions for CIFS (such as Samba
1352.2.5 or later). To enable the Unix CIFS Extensions in the Samba server, add
136the line:
137
138 unix extensions = yes
139
140to your smb.conf file on the server. Note that the following smb.conf settings
141are also useful (on the Samba server) when the majority of clients are Unix or
142Linux:
143
144 case sensitive = yes
145 delete readonly = yes
146 ea support = yes
147
148Note that server ea support is required for supporting xattrs from the Linux
149cifs client, and that EA support is present in later versions of Samba (e.g.
1503.0.6 and later (also EA support works in all versions of Windows, at least to
151shares on NTFS filesystems). Extended Attribute (xattr) support is an optional
152feature of most Linux filesystems which may require enabling via
153make menuconfig. Client support for extended attributes (user xattr) can be
154disabled on a per-mount basis by specifying "nouser_xattr" on mount.
155
156The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
157version 3.10 and later. Setting POSIX ACLs requires enabling both XATTR and
158then POSIX support in the CIFS configuration options when building the cifs
159module. POSIX ACL support can be disabled on a per mount basic by specifying
160"noacl" on mount.
161
162Some administrators may want to change Samba's smb.conf "map archive" and
163"create mask" parameters from the default. Unless the create mask is changed
164newly created files can end up with an unnecessarily restrictive default mode,
165which may not be what you want, although if the CIFS Unix extensions are
166enabled on the server and client, subsequent setattr calls (e.g. chmod) can
167fix the mode. Note that creating special devices (mknod) remotely
168may require specifying a mkdev function to Samba if you are not using
169Samba 3.0.6 or later. For more information on these see the manual pages
170("man smb.conf") on the Samba server system. Note that the cifs vfs,
171unlike the smbfs vfs, does not read the smb.conf on the client system
172(the few optional settings are passed in on mount via -o parameters instead).
173Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
174open files (required for strict POSIX compliance). Windows Servers already
175supported this feature. Samba server does not allow symlinks that refer to files
176outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
177files with absolute paths (ie beginning with slash) such as:
178 ln -s /mnt/foo bar
179would be forbidden. Samba 3.0.6 server or later includes the ability to create
180such symlinks safely by converting unsafe symlinks (ie symlinks to server
181files that are outside of the share) to a samba specific format on the server
182that is ignored by local server applications and non-cifs clients and that will
183not be traversed by the Samba server). This is opaque to the Linux client
184application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
185later, but only for remote clients using the CIFS Unix extensions, and will
186be invisbile to Windows clients and typically will not affect local
187applications running on the same server as Samba.
188
189Use instructions:
190================
191Once the CIFS VFS support is built into the kernel or installed as a module
192(cifs.o), you can use mount syntax like the following to access Samba or Windows
193servers:
194
195 mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword
196
197Before -o the option -v may be specified to make the mount.cifs
198mount helper display the mount steps more verbosely.
199After -o the following commonly used cifs vfs specific options
200are supported:
201
202 user=<username>
203 pass=<password>
204 domain=<domain name>
205
206Other cifs mount options are described below. Use of TCP names (in addition to
207ip addresses) is available if the mount helper (mount.cifs) is installed. If
208you do not trust the server to which are mounted, or if you do not have
209cifs signing enabled (and the physical network is insecure), consider use
210of the standard mount options "noexec" and "nosuid" to reduce the risk of
211running an altered binary on your local system (downloaded from a hostile server
212or altered by a hostile router).
213
214Although mounting using format corresponding to the CIFS URL specification is
215not possible in mount.cifs yet, it is possible to use an alternate format
216for the server and sharename (which is somewhat similar to NFS style mount
217syntax) instead of the more widely used UNC format (i.e. \\server\share):
218 mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd
219
220When using the mount helper mount.cifs, passwords may be specified via alternate
221mechanisms, instead of specifying it after -o using the normal "pass=" syntax
222on the command line:
2231) By including it in a credential file. Specify credentials=filename as one
224of the mount options. Credential files contain two lines
225 username=someuser
226 password=your_password
2272) By specifying the password in the PASSWD environment variable (similarly
228the user name can be taken from the USER environment variable).
2293) By specifying the password in a file by name via PASSWD_FILE
2304) By specifying the password in a file by file descriptor via PASSWD_FD
231
232If no password is provided, mount.cifs will prompt for password entry
233
234Restrictions
235============
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
Jeff Laytoncea21802007-11-20 23:19:03 +00002371001/1002 support for "Netbios-Over-TCP/IP." This is not likely to be a
238problem as most servers support this.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
240Valid filenames differ between Windows and Linux. Windows typically restricts
241filenames which contain certain reserved characters (e.g.the character :
242which is used to delimit the beginning of a stream name by Windows), while
243Linux allows a slightly wider set of valid characters in filenames. Windows
244servers can remap such characters when an explicit mapping is specified in
245the Server's registry. Samba starting with version 3.10 will allow such
246filenames (ie those which contain valid Linux characters, which normally
247would be forbidden for Windows/CIFS semantics) as long as the server is
248configured for Unix Extensions (and the client has not disabled
249/proc/fs/cifs/LinuxExtensionsEnabled).
250
251
252CIFS VFS Mount Options
253======================
254A partial list of the supported mount options follows:
255 user The user name to use when trying to establish
256 the CIFS session.
257 password The user password. If the mount helper is
258 installed, the user will be prompted for password
Steve Frenchf6d09982008-01-08 23:18:22 +0000259 if not supplied.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 ip The ip address of the target server
261 unc The target server Universal Network Name (export) to
262 mount.
263 domain Set the SMB/CIFS workgroup name prepended to the
264 username during CIFS session establishment
Steve French4523cc32007-04-30 20:13:06 +0000265 uid Set the default uid for inodes. For mounts to servers
266 which do support the CIFS Unix extensions, such as a
267 properly configured Samba server, the server provides
268 the uid, gid and mode so this parameter should not be
269 specified unless the server and clients uid and gid
270 numbering differ. If the server and client are in the
271 same domain (e.g. running winbind or nss_ldap) and
272 the server supports the Unix Extensions then the uid
273 and gid can be retrieved from the server (and uid
274 and gid would not have to be specifed on the mount.
275 For servers which do not support the CIFS Unix
276 extensions, the default uid (and gid) returned on lookup
277 of existing files will be the uid (gid) of the person
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 who executed the mount (root, except when mount.cifs
279 is configured setuid for user mounts) unless the "uid="
280 (gid) mount option is specified. For the uid (gid) of newly
281 created files and directories, ie files created since
282 the last mount of the server share, the expected uid
Matt LaPlantecab00892006-10-03 22:36:44 +0200283 (gid) is cached as long as the inode remains in
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 memory on the client. Also note that permission
285 checks (authorization checks) on accesses to a file occur
286 at the server, but there are cases in which an administrator
287 may want to restrict at the client as well. For those
288 servers which do not report a uid/gid owner
289 (such as Windows), permissions can also be checked at the
290 client, and a crude form of client side permission checking
291 can be enabled by specifying file_mode and dir_mode on
Steve French6473a552005-11-29 20:20:10 -0800292 the client. Note that the mount.cifs helper must be
293 at version 1.10 or higher to support specifying the uid
Steve Frenchf6d09982008-01-08 23:18:22 +0000294 (or gid) in non-numeric form.
Steve French4523cc32007-04-30 20:13:06 +0000295 gid Set the default gid for inodes (similar to above).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 file_mode If CIFS Unix extensions are not supported by the server
297 this overrides the default mode for file inodes.
298 dir_mode If CIFS Unix extensions are not supported by the server
299 this overrides the default mode for directory inodes.
300 port attempt to contact the server on this tcp port, before
301 trying the usual ports (port 445, then 139).
302 iocharset Codepage used to convert local path names to and from
303 Unicode. Unicode is used by default for network path
304 names if the server supports it. If iocharset is
305 not specified then the nls_default specified
306 during the local client kernel build will be used.
307 If server does not support Unicode, this parameter is
308 unused.
Steve French75865f8c2007-06-24 18:30:48 +0000309 rsize default read size (usually 16K). The client currently
310 can not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize
311 defaults to 16K and may be changed (from 8K to the maximum
312 kmalloc size allowed by your kernel) at module install time
313 for cifs.ko. Setting CIFSMaxBufSize to a very large value
314 will cause cifs to use more memory and may reduce performance
315 in some cases. To use rsize greater than 127K (the original
316 cifs protocol maximum) also requires that the server support
317 a new Unix Capability flag (for very large read) which some
318 newer servers (e.g. Samba 3.0.26 or later) do. rsize can be
319 set from a minimum of 2048 to a maximum of 130048 (127K or
320 CIFSMaxBufSize, whichever is smaller)
321 wsize default write size (default 57344)
322 maximum wsize currently allowed by CIFS is 57344 (fourteen
323 4096 byte pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 rw mount the network share read-write (note that the
325 server may still consider the share read-only)
326 ro mount network share read-only
327 version used to distinguish different versions of the
328 mount helper utility (not typically needed)
329 sep if first mount option (after the -o), overrides
330 the comma as the separator between the mount
331 parms. e.g.
332 -o user=myname,password=mypassword,domain=mydom
333 could be passed instead with period as the separator by
334 -o sep=.user=myname.password=mypassword.domain=mydom
335 this might be useful when comma is contained within username
336 or password or domain. This option is less important
337 when the cifs mount helper cifs.mount (version 1.1 or later)
338 is used.
339 nosuid Do not allow remote executables with the suid bit
340 program to be executed. This is only meaningful for mounts
341 to servers such as Samba which support the CIFS Unix Extensions.
342 If you do not trust the servers in your network (your mount
343 targets) it is recommended that you specify this option for
344 greater security.
345 exec Permit execution of binaries on the mount.
346 noexec Do not permit execution of binaries on the mount.
347 dev Recognize block devices on the remote mount.
348 nodev Do not recognize devices on the remote mount.
349 suid Allow remote files on this mountpoint with suid enabled to
350 be executed (default for mounts when executed as root,
351 nosuid is default for user mounts).
352 credentials Although ignored by the cifs kernel component, it is used by
353 the mount helper, mount.cifs. When mount.cifs is installed it
354 opens and reads the credential file specified in order
355 to obtain the userid and password arguments which are passed to
356 the cifs vfs.
357 guest Although ignored by the kernel component, the mount.cifs
358 mount helper will not prompt the user for a password
359 if guest is specified on the mount options. If no
360 password is specified a null password will be used.
361 perm Client does permission checks (vfs_permission check of uid
362 and gid of the file against the mode and desired operation),
363 Note that this is in addition to the normal ACL check on the
364 target machine done by the server software.
365 Client permission checking is enabled by default.
366 noperm Client does not do permission checks. This can expose
367 files on this mount to access by other users on the local
368 client system. It is typically only needed when the server
369 supports the CIFS Unix Extensions but the UIDs/GIDs on the
370 client and server system do not match closely enough to allow
Steve French6473a552005-11-29 20:20:10 -0800371 access by the user doing the mount, but it may be useful with
372 non CIFS Unix Extension mounts for cases in which the default
373 mode is specified on the mount but is not to be enforced on the
374 client (e.g. perhaps when MultiUserMount is enabled)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 Note that this does not affect the normal ACL check on the
376 target machine done by the server software (of the server
377 ACL against the user name provided at mount time).
Steve French7521a3c2007-07-11 18:30:34 +0000378 serverino Use server's inode numbers instead of generating automatically
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 incrementing inode numbers on the client. Although this will
380 make it easier to spot hardlinked files (as they will have
381 the same inode numbers) and inode numbers may be persistent,
382 note that the server does not guarantee that the inode numbers
383 are unique if multiple server side mounts are exported under a
384 single share (since inode numbers on the servers might not
385 be unique if multiple filesystems are mounted under the same
Steve French7521a3c2007-07-11 18:30:34 +0000386 shared higher level directory). Note that some older
387 (e.g. pre-Windows 2000) do not support returning UniqueIDs
388 or the CIFS Unix Extensions equivalent and for those
389 this mount option will have no effect. Exporting cifs mounts
390 under nfsd requires this mount option on the cifs mount.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 noserverino Client generates inode numbers (rather than using the actual one
392 from the server) by default.
393 setuids If the CIFS Unix extensions are negotiated with the server
394 the client will attempt to set the effective uid and gid of
395 the local process on newly created files, directories, and
Steve French6473a552005-11-29 20:20:10 -0800396 devices (create, mkdir, mknod). If the CIFS Unix Extensions
397 are not negotiated, for newly created files and directories
Matt LaPlantecab00892006-10-03 22:36:44 +0200398 instead of using the default uid and gid specified on
Steve French6473a552005-11-29 20:20:10 -0800399 the mount, cache the new file's uid and gid locally which means
400 that the uid for the file can change when the inode is
401 reloaded (or the user remounts the share).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 nosetuids The client will not attempt to set the uid and gid on
403 on newly created files, directories, and devices (create,
404 mkdir, mknod) which will result in the server setting the
405 uid and gid to the default (usually the server uid of the
Steve French67594fe2005-05-17 13:04:49 -0500406 user who mounted the share). Letting the server (rather than
Steve French6473a552005-11-29 20:20:10 -0800407 the client) set the uid and gid is the default. If the CIFS
408 Unix Extensions are not negotiated then the uid and gid for
409 new files will appear to be the uid (gid) of the mounter or the
410 uid (gid) parameter specified on the mount.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 netbiosname When mounting to servers via port 139, specifies the RFC1001
412 source name to use to represent the client netbios machine
413 name when doing the RFC1001 netbios session initialize.
414 direct Do not do inode data caching on files opened on this mount.
415 This precludes mmaping files on this mount. In some cases
416 with fast networks and little or no caching benefits on the
417 client (e.g. when the application is doing large sequential
418 reads bigger than page size without rereading the same data)
419 this can provide better performance than the default
Steve French67594fe2005-05-17 13:04:49 -0500420 behavior which caches reads (readahead) and writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 (writebehind) through the local Linux client pagecache
422 if oplock (caching token) is granted and held. Note that
423 direct allows write operations larger than page size
424 to be sent to the server.
425 acl Allow setfacl and getfacl to manage posix ACLs if server
426 supports them. (default)
427 noacl Do not allow setfacl and getfacl calls on this mount
Steve Frenchf6d09982008-01-08 23:18:22 +0000428 user_xattr Allow getting and setting user xattrs (those attributes whose
429 name begins with "user." or "os2.") as OS/2 EAs (extended
430 attributes) to the server. This allows support of the
431 setfattr and getfattr utilities. (default)
Steve Frenchea4c07d2006-08-16 19:44:25 +0000432 nouser_xattr Do not allow getfattr/setfattr to get/set/list xattrs
Steve French737b7582005-04-28 22:41:06 -0700433 mapchars Translate six of the seven reserved characters (not backslash)
434 *?<>|:
Steve French6a0b4822005-04-28 22:41:05 -0700435 to the remap range (above 0xF000), which also
436 allows the CIFS client to recognize files created with
437 such characters by Windows's POSIX emulation. This can
438 also be useful when mounting to most versions of Samba
439 (which also forbids creating and opening files
440 whose names contain any of these seven characters).
441 This has no effect if the server does not support
442 Unicode on the wire.
443 nomapchars Do not translate any of these seven characters (default).
Steve Frenchc46fa8a2005-08-18 20:49:57 -0700444 nocase Request case insensitive path name matching (case
445 sensitive is the default if the server suports it).
Steve Frenchf6d09982008-01-08 23:18:22 +0000446 (mount option "ignorecase" is identical to "nocase")
Steve French82940a42006-03-02 03:24:57 +0000447 posixpaths If CIFS Unix extensions are supported, attempt to
448 negotiate posix path name support which allows certain
449 characters forbidden in typical CIFS filenames, without
450 requiring remapping. (default)
451 noposixpaths If CIFS Unix extensions are supported, do not request
452 posix path name support (this may cause servers to
453 reject creatingfile with certain reserved characters).
Steve Frencha403a0a2007-07-26 15:54:16 +0000454 nounix Disable the CIFS Unix Extensions for this mount (tree
455 connection). This is rarely needed, but it may be useful
456 in order to turn off multiple settings all at once (ie
457 posix acls, posix locks, posix paths, symlink support
458 and retrieving uids/gids/mode from the server) or to
459 work around a bug in server which implement the Unix
460 Extensions.
Steve Frenchc46fa8a2005-08-18 20:49:57 -0700461 nobrl Do not send byte range lock requests to the server.
462 This is necessary for certain applications that break
463 with cifs style mandatory byte range locks (and most
464 cifs servers do not yet support requesting advisory
465 byte range locks).
Steve French2c1b8612008-10-16 18:35:21 +0000466 nodfs Disable DFS (global name space support) even if the
467 server claims to support it. This can help work around
468 a problem with parsing of DFS paths with Samba 3.0.24 server.
Steve French0cb766a2005-04-28 22:41:11 -0700469 remount remount the share (often used to change from ro to rw mounts
470 or vice versa)
Jeff Laytoncea21802007-11-20 23:19:03 +0000471 cifsacl Report mode bits (e.g. on stat) based on the Windows ACL for
472 the file. (EXPERIMENTAL)
Cyrill Gorcunov5e6e6232007-08-18 00:15:20 +0000473 servern Specify the server 's netbios name (RFC1001 name) to use
Steve Frenchad7a2922008-02-07 23:25:02 +0000474 when attempting to setup a session to the server.
Cyrill Gorcunov5e6e6232007-08-18 00:15:20 +0000475 This is needed for mounting to some older servers (such
476 as OS/2 or Windows 98 and Windows ME) since they do not
477 support a default server name. A server name can be up
478 to 15 characters long and is usually uppercased.
Steve French6473a552005-11-29 20:20:10 -0800479 sfu When the CIFS Unix Extensions are not negotiated, attempt to
480 create device files and fifos in a format compatible with
481 Services for Unix (SFU). In addition retrieve bits 10-12
482 of the mode via the SETFILEBITS extended attribute (as
Matt LaPlantecab00892006-10-03 22:36:44 +0200483 SFU does). In the future the bottom 9 bits of the
Steve French6473a552005-11-29 20:20:10 -0800484 mode also will be emulated using queries of the security
485 descriptor (ACL).
Steve French750d1152006-06-27 06:28:30 +0000486 sign Must use packet signing (helps avoid unwanted data modification
487 by intermediate systems in the route). Note that signing
488 does not work with lanman or plaintext authentication.
Steve French95b1cb92008-05-15 16:44:38 +0000489 seal Must seal (encrypt) all data on this mounted share before
490 sending on the network. Requires support for Unix Extensions.
491 Note that this differs from the sign mount option in that it
492 causes encryption of data sent over this mounted share but other
493 shares mounted to the same server are unaffected.
Steve French84210e92008-10-23 04:42:37 +0000494 locallease This option is rarely needed. Fcntl F_SETLEASE is
495 used by some applications such as Samba and NFSv4 server to
496 check to see whether a file is cacheable. CIFS has no way
497 to explicitly request a lease, but can check whether a file
498 is cacheable (oplocked). Unfortunately, even if a file
499 is not oplocked, it could still be cacheable (ie cifs client
500 could grant fcntl leases if no other local processes are using
501 the file) for cases for example such as when the server does not
502 support oplocks and the user is sure that the only updates to
503 the file will be from this client. Specifying this mount option
504 will allow the cifs client to check for leases (only) locally
505 for files which are not oplocked instead of denying leases
506 in that case. (EXPERIMENTAL)
Steve French750d1152006-06-27 06:28:30 +0000507 sec Security mode. Allowed values are:
Steve Frenchbf820672005-12-01 22:32:42 -0800508 none attempt to connection as a null user (no name)
509 krb5 Use Kerberos version 5 authentication
510 krb5i Use Kerberos authentication and packet signing
511 ntlm Use NTLM password hashing (default)
512 ntlmi Use NTLM password hashing with signing (if
513 /proc/fs/cifs/PacketSigningEnabled on or if
514 server requires signing also can be the default)
515 ntlmv2 Use NTLMv2 password hashing
516 ntlmv2i Use NTLMv2 password hashing with packet signing
Steve French189acaa2006-06-23 02:33:48 +0000517 lanman (if configured in kernel config) use older
518 lanman hash
Steve Frenchf6d09982008-01-08 23:18:22 +0000519hard Retry file operations if server is not responding
520soft Limit retries to unresponsive servers (usually only
521 one retry) before returning an error. (default)
Steve Frenchbf820672005-12-01 22:32:42 -0800522
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523The mount.cifs mount helper also accepts a few mount options before -o
524including:
525
526 -S take password from stdin (equivalent to setting the environment
527 variable "PASSWD_FD=0"
528 -V print mount.cifs version
529 -? display simple usage information
530
Jeff Layton8426c392007-05-05 03:27:49 +0000531With most 2.6 kernel versions of modutils, the version of the cifs kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532module can be displayed via modinfo.
533
534Misc /proc/fs/cifs Flags and Debug Info
535=======================================
536Informational pseudo-files:
537DebugData Displays information about active CIFS sessions
Steve French09d1db52005-04-28 22:41:08 -0700538 and shares, as well as the cifs.ko version.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539Stats Lists summary resource usage information as well as per
540 share statistics, if CONFIG_CIFS_STATS in enabled
541 in the kernel configuration.
542
543Configuration pseudo-files:
544MultiuserMount If set to one, more than one CIFS session to
545 the same server ip address can be established
546 if more than one uid accesses the same mount
547 point and if the uids user/password mapping
548 information is available. (default is 0)
549PacketSigningEnabled If set to one, cifs packet signing is enabled
550 and will be used if the server requires
551 it. If set to two, cifs packet signing is
552 required even if the server considers packet
553 signing optional. (default 1)
Steve French254e55e2006-06-04 05:53:15 +0000554SecurityFlags Flags which control security negotiation and
555 also packet signing. Authentication (may/must)
556 flags (e.g. for NTLM and/or NTLMv2) may be combined with
557 the signing flags. Specifying two different password
558 hashing mechanisms (as "must use") on the other hand
559 does not make much sense. Default flags are
560 0x07007
Steve French2e655022008-08-28 15:30:06 +0000561 (NTLM, NTLMv2 and packet signing allowed). The maximum
Steve French254e55e2006-06-04 05:53:15 +0000562 allowable flags if you want to allow mounts to servers
563 using weaker password hashes is 0x37037 (lanman,
Steve French2e655022008-08-28 15:30:06 +0000564 plaintext, ntlm, ntlmv2, signing allowed). Some
565 SecurityFlags require the corresponding menuconfig
566 options to be enabled (lanman and plaintext require
567 CONFIG_CIFS_WEAK_PW_HASH for example). Enabling
568 plaintext authentication currently requires also
569 enabling lanman authentication in the security flags
570 because the cifs module only supports sending
571 laintext passwords using the older lanman dialect
572 form of the session setup SMB. (e.g. for authentication
573 using plain text passwords, set the SecurityFlags
574 to 0x30030):
Steve French254e55e2006-06-04 05:53:15 +0000575
576 may use packet signing 0x00001
577 must use packet signing 0x01001
578 may use NTLM (most common password hash) 0x00002
579 must use NTLM 0x02002
580 may use NTLMv2 0x00004
581 must use NTLMv2 0x04004
Steve Frenchf6d09982008-01-08 23:18:22 +0000582 may use Kerberos security 0x00008
583 must use Kerberos 0x08008
Steve French254e55e2006-06-04 05:53:15 +0000584 may use lanman (weak) password hash 0x00010
585 must use lanman password hash 0x10010
586 may use plaintext passwords 0x00020
587 must use plaintext passwords 0x20020
588 (reserved for future packet encryption) 0x00040
589
Jeff Layton8426c392007-05-05 03:27:49 +0000590cifsFYI If set to non-zero value, additional debug information
591 will be logged to the system error log. This field
592 contains three flags controlling different classes of
593 debugging entries. The maximum value it can be set
594 to is 7 which enables all debugging points (default 0).
595 Some debugging statements are not compiled into the
596 cifs kernel unless CONFIG_CIFS_DEBUG2 is enabled in the
597 kernel configuration. cifsFYI may be set to one or
598 nore of the following flags (7 sets them all):
599
600 log cifs informational messages 0x01
601 log return codes from cifs entry points 0x02
Steve French0ec54aa2007-05-05 22:08:06 +0000602 log slow responses (ie which take longer than 1 second)
603 CONFIG_CIFS_STATS2 must be enabled in .config 0x04
Jeff Layton8426c392007-05-05 03:27:49 +0000604
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606traceSMB If set to one, debug information is logged to the
607 system error log with the start of smb requests
608 and responses (default 0)
609LookupCacheEnable If set to one, inode information is kept cached
610 for one second improving performance of lookups
611 (default 1)
612OplockEnabled If set to one, safe distributed caching enabled.
613 (default 1)
614LinuxExtensionsEnabled If set to one then the client will attempt to
615 use the CIFS "UNIX" extensions which are optional
616 protocol enhancements that allow CIFS servers
617 to return accurate UID/GID information as well
618 as support symbolic links. If you use servers
619 such as Samba that support the CIFS Unix
620 extensions but do not want to use symbolic link
621 support and want to map the uid and gid fields
622 to values supplied at mount (rather than the
623 actual values, then set this to zero. (default 1)
Steve French60808232006-04-22 15:53:05 +0000624Experimental When set to 1 used to enable certain experimental
625 features (currently enables multipage writes
626 when signing is enabled, the multipage write
627 performance enhancement was disabled when
628 signing turned on in case buffer was modified
629 just before it was sent, also this flag will
Jeff Laytoncea21802007-11-20 23:19:03 +0000630 be used to use the new experimental directory change
631 notification code).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632
633These experimental features and tracing can be enabled by changing flags in
634/proc/fs/cifs (after the cifs module has been installed or built into the
635kernel, e.g. insmod cifs). To enable a feature set it to 1 e.g. to enable
636tracing to the kernel message log type:
637
Steve French1047abc2005-10-11 19:58:06 -0700638 echo 7 > /proc/fs/cifs/cifsFYI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639
Steve French1047abc2005-10-11 19:58:06 -0700640cifsFYI functions as a bit mask. Setting it to 1 enables additional kernel
641logging of various informational messages. 2 enables logging of non-zero
642SMB return codes while 4 enables logging of requests that take longer
643than one second to complete (except for byte range lock requests).
644Setting it to 4 requires defining CONFIG_CIFS_STATS2 manually in the
645source code (typically by setting it in the beginning of cifsglob.h),
646and setting it to seven enables all three. Finally, tracing
647the start of smb requests and responses can be enabled via:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648
649 echo 1 > /proc/fs/cifs/traceSMB
650
Steve French75865f8c2007-06-24 18:30:48 +0000651Two other experimental features are under development. To test these
652requires enabling CONFIG_CIFS_EXPERIMENTAL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653
Jeff Laytoncea21802007-11-20 23:19:03 +0000654 cifsacl support needed to retrieve approximated mode bits based on
655 the contents on the CIFS ACL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656
Steve French84210e92008-10-23 04:42:37 +0000657 lease support: cifs will check the oplock state before calling into
658 the vfs to see if we can grant a lease on a file.
659
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 DNOTIFY fcntl: needed for support of directory change
661 notification and perhaps later for file leases)
662
663Per share (per client mount) statistics are available in /proc/fs/cifs/Stats
664if the kernel was configured with cifs statistics enabled. The statistics
665represent the number of successful (ie non-zero return code from the server)
666SMB responses to some of the more common commands (open, delete, mkdir etc.).
667Also recorded is the total bytes read and bytes written to the server for
668that share. Note that due to client caching effects this can be less than the
669number of bytes read and written by the application running on the client.
670The statistics for the number of total SMBs and oplock breaks are different in
671that they represent all for that share, not just those for which the server
672returned success.
673
Steve French3d2af342008-08-19 20:51:09 +0000674Also note that "cat /proc/fs/cifs/DebugData" will display information about
Jeff Laytoncea21802007-11-20 23:19:03 +0000675the active sessions and the shares that are mounted.
Steve French3d2af342008-08-19 20:51:09 +0000676
677Enabling Kerberos (extended security) works but requires version 1.2 or later
678of the helper program cifs.upcall to be present and to be configured in the
679/etc/request-key.conf file. The cifs.upcall helper program is from the Samba
680project(http://www.samba.org). NTLM and NTLMv2 and LANMAN support do not
681require this helper. Note that NTLMv2 security (which does not require the
682cifs.upcall helper program), instead of using Kerberos, is sufficient for
683some use cases.
684
685Enabling DFS support (used to access shares transparently in an MS-DFS
686global name space) requires that CONFIG_CIFS_EXPERIMENTAL be enabled. In
687addition, DFS support for target shares which are specified as UNC
688names which begin with host names (rather than IP addresses) requires
689a user space helper (such as cifs.upcall) to be present in order to
690translate host names to ip address, and the user space helper must also
691be configured in the file /etc/request-key.conf
692
693To use cifs Kerberos and DFS support, the Linux keyutils package should be
694installed and something like the following lines should be added to the
695/etc/request-key.conf file:
696
697create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
698create dns_resolver * * /usr/local/sbin/cifs.upcall %k
699
700