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  1. The CIFS VFS support for Linux supports many advanced network filesystem
  2. features such as hierarchical dfs like namespace, hardlinks, locking and more.
  3. It was designed to comply with the SNIA CIFS Technical Reference (which
  4. supersedes the 1992 X/Open SMB Standard) as well as to perform best practice
  5. practical interoperability with Windows 2000, Windows XP, Samba and equivalent
  6. servers.
  7. For questions or bug reports please contact:
  8. sfrench@samba.org (sfrench@us.ibm.com)
  9. Build instructions:
  10. ==================
  11. For Linux 2.4:
  12. 1) Get the kernel source (e.g.from http://www.kernel.org)
  13. and download the cifs vfs source (see the project page
  14. at http://us1.samba.org/samba/Linux_CIFS_client.html)
  15. and change directory into the top of the kernel directory
  16. then patch the kernel (e.g. "patch -p1 < cifs_24.patch")
  17. to add the cifs vfs to your kernel configure options if
  18. it has not already been added (e.g. current SuSE and UL
  19. users do not need to apply the cifs_24.patch since the cifs vfs is
  20. already in the kernel configure menu) and then
  21. mkdir linux/fs/cifs and then copy the current cifs vfs files from
  22. the cifs download to your kernel build directory e.g.
  23. cp <cifs_download_dir>/fs/cifs/* to <kernel_download_dir>/fs/cifs
  24. 2) make menuconfig (or make xconfig)
  25. 3) select cifs from within the network filesystem choices
  26. 4) save and exit
  27. 5) make dep
  28. 6) make modules (or "make" if CIFS VFS not to be built as a module)
  29. For Linux 2.6:
  30. 1) Download the kernel (e.g. from http://www.kernel.org)
  31. and change directory into the top of the kernel directory tree
  32. (e.g. /usr/src/linux-2.5.73)
  33. 2) make menuconfig (or make xconfig)
  34. 3) select cifs from within the network filesystem choices
  35. 4) save and exit
  36. 5) make
  37. Installation instructions:
  38. =========================
  39. If you have built the CIFS vfs as module (successfully) simply
  40. type "make modules_install" (or if you prefer, manually copy the file to
  41. the modules directory e.g. /lib/modules/2.4.10-4GB/kernel/fs/cifs/cifs.o).
  42. If you have built the CIFS vfs into the kernel itself, follow the instructions
  43. for your distribution on how to install a new kernel (usually you
  44. would simply type "make install").
  45. If you do not have the utility mount.cifs (in the Samba 3.0 source tree and on
  46. the CIFS VFS web site) copy it to the same directory in which mount.smbfs and
  47. similar files reside (usually /sbin). Although the helper software is not
  48. required, mount.cifs is recommended. Eventually the Samba 3.0 utility program
  49. "net" may also be helpful since it may someday provide easier mount syntax for
  50. users who are used to Windows e.g. net use <mount point> <UNC name or cifs URL>
  51. Note that running the Winbind pam/nss module (logon service) on all of your
  52. Linux clients is useful in mapping Uids and Gids consistently across the
  53. domain to the proper network user. The mount.cifs mount helper can be
  54. trivially built from Samba 3.0 or later source e.g. by executing:
  55. gcc samba/source/client/mount.cifs.c -o mount.cifs
  56. If cifs is built as a module, then the size and number of network buffers
  57. and maximum number of simultaneous requests to one server can be configured.
  58. Changing these from their defaults is not recommended. By executing modinfo
  59. modinfo kernel/fs/cifs/cifs.ko
  60. on kernel/fs/cifs/cifs.ko the list of configuration changes that can be made
  61. at module initialization time (by running insmod cifs.ko) can be seen.
  62. Allowing User Mounts
  63. ====================
  64. To permit users to mount and unmount over directories they own is possible
  65. with the cifs vfs. A way to enable such mounting is to mark the mount.cifs
  66. utility as suid (e.g. "chmod +s /sbin/mount.cifs). To enable users to
  67. umount shares they mount requires
  68. 1) mount.cifs version 1.4 or later
  69. 2) an entry for the share in /etc/fstab indicating that a user may
  70. unmount it e.g.
  71. //server/usersharename /mnt/username cifs user 0 0
  72. Note that when the mount.cifs utility is run suid (allowing user mounts),
  73. in order to reduce risks, the "nosuid" mount flag is passed in on mount to
  74. disallow execution of an suid program mounted on the remote target.
  75. When mount is executed as root, nosuid is not passed in by default,
  76. and execution of suid programs on the remote target would be enabled
  77. by default. This can be changed, as with nfs and other filesystems,
  78. by simply specifying "nosuid" among the mount options. For user mounts
  79. though to be able to pass the suid flag to mount requires rebuilding
  80. mount.cifs with the following flag:
  81. gcc samba/source/client/mount.cifs.c -DCIFS_ALLOW_USR_SUID -o mount.cifs
  82. There is a corresponding manual page for cifs mounting in the Samba 3.0 and
  83. later source tree in docs/manpages/mount.cifs.8
  84. Allowing User Unmounts
  85. ======================
  86. To permit users to ummount directories that they have user mounted (see above),
  87. the utility umount.cifs may be used. It may be invoked directly, or if
  88. umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
  89. (at least for most versions of the umount utility) for umount of cifs
  90. mounts, unless umount is invoked with -i (which will avoid invoking a umount
  91. helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
  92. as suid (e.g. "chmod +s /sbin/umount.cifs") or equivalent (some distributions
  93. allow adding entries to a file to the /etc/permissions file to achieve the
  94. equivalent suid effect). For this utility to succeed the target path
  95. must be a cifs mount, and the uid of the current user must match the uid
  96. of the user who mounted the resource.
  97. Also note that the customary way of allowing user mounts and unmounts is
  98. (instead of using mount.cifs and unmount.cifs as suid) to add a line
  99. to the file /etc/fstab for each //server/share you wish to mount, but
  100. this can become unwieldy when potential mount targets include many
  101. or unpredictable UNC names.
  102. Samba Considerations
  103. ====================
  104. To get the maximum benefit from the CIFS VFS, we recommend using a server that
  105. supports the SNIA CIFS Unix Extensions standard (e.g. Samba 2.2.5 or later or
  106. Samba 3.0) but the CIFS vfs works fine with a wide variety of CIFS servers.
  107. Note that uid, gid and file permissions will display default values if you do
  108. not have a server that supports the Unix extensions for CIFS (such as Samba
  109. 2.2.5 or later). To enable the Unix CIFS Extensions in the Samba server, add
  110. the line:
  111. unix extensions = yes
  112. to your smb.conf file on the server. Note that the following smb.conf settings
  113. are also useful (on the Samba server) when the majority of clients are Unix or
  114. Linux:
  115. case sensitive = yes
  116. delete readonly = yes
  117. ea support = yes
  118. Note that server ea support is required for supporting xattrs from the Linux
  119. cifs client, and that EA support is present in later versions of Samba (e.g.
  120. 3.0.6 and later (also EA support works in all versions of Windows, at least to
  121. shares on NTFS filesystems). Extended Attribute (xattr) support is an optional
  122. feature of most Linux filesystems which may require enabling via
  123. make menuconfig. Client support for extended attributes (user xattr) can be
  124. disabled on a per-mount basis by specifying "nouser_xattr" on mount.
  125. The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
  126. version 3.10 and later. Setting POSIX ACLs requires enabling both XATTR and
  127. then POSIX support in the CIFS configuration options when building the cifs
  128. module. POSIX ACL support can be disabled on a per mount basic by specifying
  129. "noacl" on mount.
  130. Some administrators may want to change Samba's smb.conf "map archive" and
  131. "create mask" parameters from the default. Unless the create mask is changed
  132. newly created files can end up with an unnecessarily restrictive default mode,
  133. which may not be what you want, although if the CIFS Unix extensions are
  134. enabled on the server and client, subsequent setattr calls (e.g. chmod) can
  135. fix the mode. Note that creating special devices (mknod) remotely
  136. may require specifying a mkdev function to Samba if you are not using
  137. Samba 3.0.6 or later. For more information on these see the manual pages
  138. ("man smb.conf") on the Samba server system. Note that the cifs vfs,
  139. unlike the smbfs vfs, does not read the smb.conf on the client system
  140. (the few optional settings are passed in on mount via -o parameters instead).
  141. Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
  142. open files (required for strict POSIX compliance). Windows Servers already
  143. supported this feature. Samba server does not allow symlinks that refer to files
  144. outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
  145. files with absolute paths (ie beginning with slash) such as:
  146. ln -s /mnt/foo bar
  147. would be forbidden. Samba 3.0.6 server or later includes the ability to create
  148. such symlinks safely by converting unsafe symlinks (ie symlinks to server
  149. files that are outside of the share) to a samba specific format on the server
  150. that is ignored by local server applications and non-cifs clients and that will
  151. not be traversed by the Samba server). This is opaque to the Linux client
  152. application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
  153. later, but only for remote clients using the CIFS Unix extensions, and will
  154. be invisbile to Windows clients and typically will not affect local
  155. applications running on the same server as Samba.
  156. Use instructions:
  157. ================
  158. Once the CIFS VFS support is built into the kernel or installed as a module
  159. (cifs.o), you can use mount syntax like the following to access Samba or Windows
  160. servers:
  161. mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword
  162. Before -o the option -v may be specified to make the mount.cifs
  163. mount helper display the mount steps more verbosely.
  164. After -o the following commonly used cifs vfs specific options
  165. are supported:
  166. user=<username>
  167. pass=<password>
  168. domain=<domain name>
  169. Other cifs mount options are described below. Use of TCP names (in addition to
  170. ip addresses) is available if the mount helper (mount.cifs) is installed. If
  171. you do not trust the server to which are mounted, or if you do not have
  172. cifs signing enabled (and the physical network is insecure), consider use
  173. of the standard mount options "noexec" and "nosuid" to reduce the risk of
  174. running an altered binary on your local system (downloaded from a hostile server
  175. or altered by a hostile router).
  176. Although mounting using format corresponding to the CIFS URL specification is
  177. not possible in mount.cifs yet, it is possible to use an alternate format
  178. for the server and sharename (which is somewhat similar to NFS style mount
  179. syntax) instead of the more widely used UNC format (i.e. \\server\share):
  180. mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd
  181. When using the mount helper mount.cifs, passwords may be specified via alternate
  182. mechanisms, instead of specifying it after -o using the normal "pass=" syntax
  183. on the command line:
  184. 1) By including it in a credential file. Specify credentials=filename as one
  185. of the mount options. Credential files contain two lines
  186. username=someuser
  187. password=your_password
  188. 2) By specifying the password in the PASSWD environment variable (similarly
  189. the user name can be taken from the USER environment variable).
  190. 3) By specifying the password in a file by name via PASSWD_FILE
  191. 4) By specifying the password in a file by file descriptor via PASSWD_FD
  192. If no password is provided, mount.cifs will prompt for password entry
  193. Restrictions
  194. ============
  195. Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
  196. 1001/1002 support for "Netbios-Over-TCP/IP." This is not likely to be a
  197. problem as most servers support this.
  198. Valid filenames differ between Windows and Linux. Windows typically restricts
  199. filenames which contain certain reserved characters (e.g.the character :
  200. which is used to delimit the beginning of a stream name by Windows), while
  201. Linux allows a slightly wider set of valid characters in filenames. Windows
  202. servers can remap such characters when an explicit mapping is specified in
  203. the Server's registry. Samba starting with version 3.10 will allow such
  204. filenames (ie those which contain valid Linux characters, which normally
  205. would be forbidden for Windows/CIFS semantics) as long as the server is
  206. configured for Unix Extensions (and the client has not disabled
  207. /proc/fs/cifs/LinuxExtensionsEnabled).
  208. CIFS VFS Mount Options
  209. ======================
  210. A partial list of the supported mount options follows:
  211. user The user name to use when trying to establish
  212. the CIFS session.
  213. password The user password. If the mount helper is
  214. installed, the user will be prompted for password
  215. if it is not supplied.
  216. ip The ip address of the target server
  217. unc The target server Universal Network Name (export) to
  218. mount.
  219. domain Set the SMB/CIFS workgroup name prepended to the
  220. username during CIFS session establishment
  221. uid Set the default uid for inodes. For mounts to servers
  222. which do support the CIFS Unix extensions, such as a
  223. properly configured Samba server, the server provides
  224. the uid, gid and mode so this parameter should not be
  225. specified unless the server and clients uid and gid
  226. numbering differ. If the server and client are in the
  227. same domain (e.g. running winbind or nss_ldap) and
  228. the server supports the Unix Extensions then the uid
  229. and gid can be retrieved from the server (and uid
  230. and gid would not have to be specifed on the mount.
  231. For servers which do not support the CIFS Unix
  232. extensions, the default uid (and gid) returned on lookup
  233. of existing files will be the uid (gid) of the person
  234. who executed the mount (root, except when mount.cifs
  235. is configured setuid for user mounts) unless the "uid="
  236. (gid) mount option is specified. For the uid (gid) of newly
  237. created files and directories, ie files created since
  238. the last mount of the server share, the expected uid
  239. (gid) is cached as long as the inode remains in
  240. memory on the client. Also note that permission
  241. checks (authorization checks) on accesses to a file occur
  242. at the server, but there are cases in which an administrator
  243. may want to restrict at the client as well. For those
  244. servers which do not report a uid/gid owner
  245. (such as Windows), permissions can also be checked at the
  246. client, and a crude form of client side permission checking
  247. can be enabled by specifying file_mode and dir_mode on
  248. the client. Note that the mount.cifs helper must be
  249. at version 1.10 or higher to support specifying the uid
  250. (or gid) in non-numberic form.
  251. gid Set the default gid for inodes (similar to above).
  252. file_mode If CIFS Unix extensions are not supported by the server
  253. this overrides the default mode for file inodes.
  254. dir_mode If CIFS Unix extensions are not supported by the server
  255. this overrides the default mode for directory inodes.
  256. port attempt to contact the server on this tcp port, before
  257. trying the usual ports (port 445, then 139).
  258. iocharset Codepage used to convert local path names to and from
  259. Unicode. Unicode is used by default for network path
  260. names if the server supports it. If iocharset is
  261. not specified then the nls_default specified
  262. during the local client kernel build will be used.
  263. If server does not support Unicode, this parameter is
  264. unused.
  265. rsize default read size (usually 16K). The client currently
  266. can not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize
  267. defaults to 16K and may be changed (from 8K to the maximum
  268. kmalloc size allowed by your kernel) at module install time
  269. for cifs.ko. Setting CIFSMaxBufSize to a very large value
  270. will cause cifs to use more memory and may reduce performance
  271. in some cases. To use rsize greater than 127K (the original
  272. cifs protocol maximum) also requires that the server support
  273. a new Unix Capability flag (for very large read) which some
  274. newer servers (e.g. Samba 3.0.26 or later) do. rsize can be
  275. set from a minimum of 2048 to a maximum of 130048 (127K or
  276. CIFSMaxBufSize, whichever is smaller)
  277. wsize default write size (default 57344)
  278. maximum wsize currently allowed by CIFS is 57344 (fourteen
  279. 4096 byte pages)
  280. rw mount the network share read-write (note that the
  281. server may still consider the share read-only)
  282. ro mount network share read-only
  283. version used to distinguish different versions of the
  284. mount helper utility (not typically needed)
  285. sep if first mount option (after the -o), overrides
  286. the comma as the separator between the mount
  287. parms. e.g.
  288. -o user=myname,password=mypassword,domain=mydom
  289. could be passed instead with period as the separator by
  290. -o sep=.user=myname.password=mypassword.domain=mydom
  291. this might be useful when comma is contained within username
  292. or password or domain. This option is less important
  293. when the cifs mount helper cifs.mount (version 1.1 or later)
  294. is used.
  295. nosuid Do not allow remote executables with the suid bit
  296. program to be executed. This is only meaningful for mounts
  297. to servers such as Samba which support the CIFS Unix Extensions.
  298. If you do not trust the servers in your network (your mount
  299. targets) it is recommended that you specify this option for
  300. greater security.
  301. exec Permit execution of binaries on the mount.
  302. noexec Do not permit execution of binaries on the mount.
  303. dev Recognize block devices on the remote mount.
  304. nodev Do not recognize devices on the remote mount.
  305. suid Allow remote files on this mountpoint with suid enabled to
  306. be executed (default for mounts when executed as root,
  307. nosuid is default for user mounts).
  308. credentials Although ignored by the cifs kernel component, it is used by
  309. the mount helper, mount.cifs. When mount.cifs is installed it
  310. opens and reads the credential file specified in order
  311. to obtain the userid and password arguments which are passed to
  312. the cifs vfs.
  313. guest Although ignored by the kernel component, the mount.cifs
  314. mount helper will not prompt the user for a password
  315. if guest is specified on the mount options. If no
  316. password is specified a null password will be used.
  317. perm Client does permission checks (vfs_permission check of uid
  318. and gid of the file against the mode and desired operation),
  319. Note that this is in addition to the normal ACL check on the
  320. target machine done by the server software.
  321. Client permission checking is enabled by default.
  322. noperm Client does not do permission checks. This can expose
  323. files on this mount to access by other users on the local
  324. client system. It is typically only needed when the server
  325. supports the CIFS Unix Extensions but the UIDs/GIDs on the
  326. client and server system do not match closely enough to allow
  327. access by the user doing the mount, but it may be useful with
  328. non CIFS Unix Extension mounts for cases in which the default
  329. mode is specified on the mount but is not to be enforced on the
  330. client (e.g. perhaps when MultiUserMount is enabled)
  331. Note that this does not affect the normal ACL check on the
  332. target machine done by the server software (of the server
  333. ACL against the user name provided at mount time).
  334. serverino Use server's inode numbers instead of generating automatically
  335. incrementing inode numbers on the client. Although this will
  336. make it easier to spot hardlinked files (as they will have
  337. the same inode numbers) and inode numbers may be persistent,
  338. note that the server does not guarantee that the inode numbers
  339. are unique if multiple server side mounts are exported under a
  340. single share (since inode numbers on the servers might not
  341. be unique if multiple filesystems are mounted under the same
  342. shared higher level directory). Note that some older
  343. (e.g. pre-Windows 2000) do not support returning UniqueIDs
  344. or the CIFS Unix Extensions equivalent and for those
  345. this mount option will have no effect. Exporting cifs mounts
  346. under nfsd requires this mount option on the cifs mount.
  347. noserverino Client generates inode numbers (rather than using the actual one
  348. from the server) by default.
  349. setuids If the CIFS Unix extensions are negotiated with the server
  350. the client will attempt to set the effective uid and gid of
  351. the local process on newly created files, directories, and
  352. devices (create, mkdir, mknod). If the CIFS Unix Extensions
  353. are not negotiated, for newly created files and directories
  354. instead of using the default uid and gid specified on
  355. the mount, cache the new file's uid and gid locally which means
  356. that the uid for the file can change when the inode is
  357. reloaded (or the user remounts the share).
  358. nosetuids The client will not attempt to set the uid and gid on
  359. on newly created files, directories, and devices (create,
  360. mkdir, mknod) which will result in the server setting the
  361. uid and gid to the default (usually the server uid of the
  362. user who mounted the share). Letting the server (rather than
  363. the client) set the uid and gid is the default. If the CIFS
  364. Unix Extensions are not negotiated then the uid and gid for
  365. new files will appear to be the uid (gid) of the mounter or the
  366. uid (gid) parameter specified on the mount.
  367. netbiosname When mounting to servers via port 139, specifies the RFC1001
  368. source name to use to represent the client netbios machine
  369. name when doing the RFC1001 netbios session initialize.
  370. direct Do not do inode data caching on files opened on this mount.
  371. This precludes mmaping files on this mount. In some cases
  372. with fast networks and little or no caching benefits on the
  373. client (e.g. when the application is doing large sequential
  374. reads bigger than page size without rereading the same data)
  375. this can provide better performance than the default
  376. behavior which caches reads (readahead) and writes
  377. (writebehind) through the local Linux client pagecache
  378. if oplock (caching token) is granted and held. Note that
  379. direct allows write operations larger than page size
  380. to be sent to the server.
  381. acl Allow setfacl and getfacl to manage posix ACLs if server
  382. supports them. (default)
  383. noacl Do not allow setfacl and getfacl calls on this mount
  384. user_xattr Allow getting and setting user xattrs as OS/2 EAs (extended
  385. attributes) to the server (default) e.g. via setfattr
  386. and getfattr utilities.
  387. nouser_xattr Do not allow getfattr/setfattr to get/set/list xattrs
  388. mapchars Translate six of the seven reserved characters (not backslash)
  389. *?<>|:
  390. to the remap range (above 0xF000), which also
  391. allows the CIFS client to recognize files created with
  392. such characters by Windows's POSIX emulation. This can
  393. also be useful when mounting to most versions of Samba
  394. (which also forbids creating and opening files
  395. whose names contain any of these seven characters).
  396. This has no effect if the server does not support
  397. Unicode on the wire.
  398. nomapchars Do not translate any of these seven characters (default).
  399. nocase Request case insensitive path name matching (case
  400. sensitive is the default if the server suports it).
  401. posixpaths If CIFS Unix extensions are supported, attempt to
  402. negotiate posix path name support which allows certain
  403. characters forbidden in typical CIFS filenames, without
  404. requiring remapping. (default)
  405. noposixpaths If CIFS Unix extensions are supported, do not request
  406. posix path name support (this may cause servers to
  407. reject creatingfile with certain reserved characters).
  408. nounix Disable the CIFS Unix Extensions for this mount (tree
  409. connection). This is rarely needed, but it may be useful
  410. in order to turn off multiple settings all at once (ie
  411. posix acls, posix locks, posix paths, symlink support
  412. and retrieving uids/gids/mode from the server) or to
  413. work around a bug in server which implement the Unix
  414. Extensions.
  415. nobrl Do not send byte range lock requests to the server.
  416. This is necessary for certain applications that break
  417. with cifs style mandatory byte range locks (and most
  418. cifs servers do not yet support requesting advisory
  419. byte range locks).
  420. remount remount the share (often used to change from ro to rw mounts
  421. or vice versa)
  422. cifsacl Report mode bits (e.g. on stat) based on the Windows ACL for
  423. the file. (EXPERIMENTAL)
  424. servern Specify the server 's netbios name (RFC1001 name) to use
  425. when attempting to setup a session to the server. This is
  426. This is needed for mounting to some older servers (such
  427. as OS/2 or Windows 98 and Windows ME) since they do not
  428. support a default server name. A server name can be up
  429. to 15 characters long and is usually uppercased.
  430. sfu When the CIFS Unix Extensions are not negotiated, attempt to
  431. create device files and fifos in a format compatible with
  432. Services for Unix (SFU). In addition retrieve bits 10-12
  433. of the mode via the SETFILEBITS extended attribute (as
  434. SFU does). In the future the bottom 9 bits of the
  435. mode also will be emulated using queries of the security
  436. descriptor (ACL).
  437. sign Must use packet signing (helps avoid unwanted data modification
  438. by intermediate systems in the route). Note that signing
  439. does not work with lanman or plaintext authentication.
  440. sec Security mode. Allowed values are:
  441. none attempt to connection as a null user (no name)
  442. krb5 Use Kerberos version 5 authentication
  443. krb5i Use Kerberos authentication and packet signing
  444. ntlm Use NTLM password hashing (default)
  445. ntlmi Use NTLM password hashing with signing (if
  446. /proc/fs/cifs/PacketSigningEnabled on or if
  447. server requires signing also can be the default)
  448. ntlmv2 Use NTLMv2 password hashing
  449. ntlmv2i Use NTLMv2 password hashing with packet signing
  450. lanman (if configured in kernel config) use older
  451. lanman hash
  452. The mount.cifs mount helper also accepts a few mount options before -o
  453. including:
  454. -S take password from stdin (equivalent to setting the environment
  455. variable "PASSWD_FD=0"
  456. -V print mount.cifs version
  457. -? display simple usage information
  458. With most 2.6 kernel versions of modutils, the version of the cifs kernel
  459. module can be displayed via modinfo.
  460. Misc /proc/fs/cifs Flags and Debug Info
  461. =======================================
  462. Informational pseudo-files:
  463. DebugData Displays information about active CIFS sessions
  464. and shares, as well as the cifs.ko version.
  465. Stats Lists summary resource usage information as well as per
  466. share statistics, if CONFIG_CIFS_STATS in enabled
  467. in the kernel configuration.
  468. Configuration pseudo-files:
  469. MultiuserMount If set to one, more than one CIFS session to
  470. the same server ip address can be established
  471. if more than one uid accesses the same mount
  472. point and if the uids user/password mapping
  473. information is available. (default is 0)
  474. PacketSigningEnabled If set to one, cifs packet signing is enabled
  475. and will be used if the server requires
  476. it. If set to two, cifs packet signing is
  477. required even if the server considers packet
  478. signing optional. (default 1)
  479. SecurityFlags Flags which control security negotiation and
  480. also packet signing. Authentication (may/must)
  481. flags (e.g. for NTLM and/or NTLMv2) may be combined with
  482. the signing flags. Specifying two different password
  483. hashing mechanisms (as "must use") on the other hand
  484. does not make much sense. Default flags are
  485. 0x07007
  486. (NTLM, NTLMv2 and packet signing allowed). Maximum
  487. allowable flags if you want to allow mounts to servers
  488. using weaker password hashes is 0x37037 (lanman,
  489. plaintext, ntlm, ntlmv2, signing allowed):
  490. may use packet signing 0x00001
  491. must use packet signing 0x01001
  492. may use NTLM (most common password hash) 0x00002
  493. must use NTLM 0x02002
  494. may use NTLMv2 0x00004
  495. must use NTLMv2 0x04004
  496. may use Kerberos security (not implemented yet) 0x00008
  497. must use Kerberos (not implemented yet) 0x08008
  498. may use lanman (weak) password hash 0x00010
  499. must use lanman password hash 0x10010
  500. may use plaintext passwords 0x00020
  501. must use plaintext passwords 0x20020
  502. (reserved for future packet encryption) 0x00040
  503. cifsFYI If set to non-zero value, additional debug information
  504. will be logged to the system error log. This field
  505. contains three flags controlling different classes of
  506. debugging entries. The maximum value it can be set
  507. to is 7 which enables all debugging points (default 0).
  508. Some debugging statements are not compiled into the
  509. cifs kernel unless CONFIG_CIFS_DEBUG2 is enabled in the
  510. kernel configuration. cifsFYI may be set to one or
  511. nore of the following flags (7 sets them all):
  512. log cifs informational messages 0x01
  513. log return codes from cifs entry points 0x02
  514. log slow responses (ie which take longer than 1 second)
  515. CONFIG_CIFS_STATS2 must be enabled in .config 0x04
  516. traceSMB If set to one, debug information is logged to the
  517. system error log with the start of smb requests
  518. and responses (default 0)
  519. LookupCacheEnable If set to one, inode information is kept cached
  520. for one second improving performance of lookups
  521. (default 1)
  522. OplockEnabled If set to one, safe distributed caching enabled.
  523. (default 1)
  524. LinuxExtensionsEnabled If set to one then the client will attempt to
  525. use the CIFS "UNIX" extensions which are optional
  526. protocol enhancements that allow CIFS servers
  527. to return accurate UID/GID information as well
  528. as support symbolic links. If you use servers
  529. such as Samba that support the CIFS Unix
  530. extensions but do not want to use symbolic link
  531. support and want to map the uid and gid fields
  532. to values supplied at mount (rather than the
  533. actual values, then set this to zero. (default 1)
  534. Experimental When set to 1 used to enable certain experimental
  535. features (currently enables multipage writes
  536. when signing is enabled, the multipage write
  537. performance enhancement was disabled when
  538. signing turned on in case buffer was modified
  539. just before it was sent, also this flag will
  540. be used to use the new experimental directory change
  541. notification code).
  542. These experimental features and tracing can be enabled by changing flags in
  543. /proc/fs/cifs (after the cifs module has been installed or built into the
  544. kernel, e.g. insmod cifs). To enable a feature set it to 1 e.g. to enable
  545. tracing to the kernel message log type:
  546. echo 7 > /proc/fs/cifs/cifsFYI
  547. cifsFYI functions as a bit mask. Setting it to 1 enables additional kernel
  548. logging of various informational messages. 2 enables logging of non-zero
  549. SMB return codes while 4 enables logging of requests that take longer
  550. than one second to complete (except for byte range lock requests).
  551. Setting it to 4 requires defining CONFIG_CIFS_STATS2 manually in the
  552. source code (typically by setting it in the beginning of cifsglob.h),
  553. and setting it to seven enables all three. Finally, tracing
  554. the start of smb requests and responses can be enabled via:
  555. echo 1 > /proc/fs/cifs/traceSMB
  556. Two other experimental features are under development. To test these
  557. requires enabling CONFIG_CIFS_EXPERIMENTAL
  558. cifsacl support needed to retrieve approximated mode bits based on
  559. the contents on the CIFS ACL.
  560. DNOTIFY fcntl: needed for support of directory change
  561. notification and perhaps later for file leases)
  562. Per share (per client mount) statistics are available in /proc/fs/cifs/Stats
  563. if the kernel was configured with cifs statistics enabled. The statistics
  564. represent the number of successful (ie non-zero return code from the server)
  565. SMB responses to some of the more common commands (open, delete, mkdir etc.).
  566. Also recorded is the total bytes read and bytes written to the server for
  567. that share. Note that due to client caching effects this can be less than the
  568. number of bytes read and written by the application running on the client.
  569. The statistics for the number of total SMBs and oplock breaks are different in
  570. that they represent all for that share, not just those for which the server
  571. returned success.
  572. Also note that "cat /proc/fs/cifs/DebugData" will display information about
  573. the active sessions and the shares that are mounted.
  574. Enabling Kerberos (extended security) works when CONFIG_CIFS_EXPERIMENTAL is enabled
  575. but requires a user space helper (from the Samba project). NTLM and NTLMv2 and
  576. LANMAN support do not require this helpr.