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authorJeff Layton <jlayton@redhat.com>2013-09-05 08:38:11 -0400
committerSteve French <smfrench@gmail.com>2013-09-08 14:24:10 -0500
commit30706a545417af50f07b8e47cc2189a2e20a4636 (patch)
tree1dc52316aaa356ba728ec0b612799c314fb9d410 /fs/cifs/README
parent73e216a8a42c0ef3d08071705c946c38fdbe12b0 (diff)
cifs: create a new Documentation/ directory and move docfiles into it
Currently, we have a number of documentation files that live under fs/cifs/. Generally, these don't get picked up by distro packagers, since they're in a non-standard location. Move them to a new spot under Documentation/ instead. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
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-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. This code was developed in participation with the Protocol Freedom
-Information Foundation.
-
-Please see
- http://protocolfreedom.org/ and
- http://samba.org/samba/PFIF/
-for more details.
-
-
-For questions or bug reports please contact:
- sfrench@samba.org (sfrench@us.ibm.com)
-
-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
-mechanisms, instead of specifying it after -o using the normal "pass=" syntax
-on the command line:
-1) By including it in a credential file. Specify credentials=filename as one
-of the mount options. Credential files contain two lines
- username=someuser
- password=your_password
-2) By specifying the password in the PASSWD environment variable (similarly
-the user name can be taken from the USER environment variable).
-3) By specifying the password in a file by name via PASSWD_FILE
-4) By specifying the password in a file by file descriptor via PASSWD_FD
-
-If no password is provided, mount.cifs will prompt for password entry
-
-Restrictions
-============
-Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
-1001/1002 support for "Netbios-Over-TCP/IP." This is not likely to be a
-problem as most servers support this.
-
-Valid filenames differ between Windows and Linux. Windows typically restricts
-filenames which contain certain reserved characters (e.g.the character :
-which is used to delimit the beginning of a stream name by Windows), while
-Linux allows a slightly wider set of valid characters in filenames. Windows
-servers can remap such characters when an explicit mapping is specified in
-the Server's registry. Samba starting with version 3.10 will allow such
-filenames (ie those which contain valid Linux characters, which normally
-would be forbidden for Windows/CIFS semantics) as long as the server is
-configured for Unix Extensions (and the client has not disabled
-/proc/fs/cifs/LinuxExtensionsEnabled).
-
-
-CIFS VFS Mount Options
-======================
-A partial list of the supported mount options follows:
- user The user name to use when trying to establish
- the CIFS session.
- password The user password. If the mount helper is
- installed, the user will be prompted for password
- if not supplied.
- ip The ip address of the target server
- unc The target server Universal Network Name (export) to
- mount.
- domain Set the SMB/CIFS workgroup name prepended to the
- username during CIFS session establishment
- forceuid Set the default uid for inodes to the uid
- passed in on mount. For mounts to servers
- which do support the CIFS Unix extensions, such as a
- properly configured Samba server, the server provides
- the uid, gid and mode so this parameter should not be
- specified unless the server and clients uid and gid
- numbering differ. If the server and client are in the
- same domain (e.g. running winbind or nss_ldap) and
- the server supports the Unix Extensions then the uid
- and gid can be retrieved from the server (and uid
- and gid would not have to be specifed on the mount.
- For servers which do not support the CIFS Unix
- extensions, the default uid (and gid) returned on lookup
- of existing files will be the uid (gid) of the person
- who executed the mount (root, except when mount.cifs
- is configured setuid for user mounts) unless the "uid="
- (gid) mount option is specified. Also note that permission
- checks (authorization checks) on accesses to a file occur
- at the server, but there are cases in which an administrator
- may want to restrict at the client as well. For those
- servers which do not report a uid/gid owner
- (such as Windows), permissions can also be checked at the
- client, and a crude form of client side permission checking
- can be enabled by specifying file_mode and dir_mode on
- the client. (default)
- forcegid (similar to above but for the groupid instead of uid) (default)
- noforceuid Fill in file owner information (uid) by requesting it from
- the server if possible. With this option, the value given in
- the uid= option (on mount) will only be used if the server
- can not support returning uids on inodes.
- noforcegid (similar to above but for the group owner, gid, instead of uid)
- uid Set the default uid for inodes, and indicate to the
- cifs kernel driver which local user mounted. If the server
- supports the unix extensions the default uid is
- not used to fill in the owner fields of inodes (files)
- unless the "forceuid" parameter is specified.
- gid Set the default gid for inodes (similar to above).
- file_mode If CIFS Unix extensions are not supported by the server
- this overrides the default mode for file inodes.
- fsc Enable local disk caching using FS-Cache (off by default). This
- option could be useful to improve performance on a slow link,
- heavily loaded server and/or network where reading from the
- disk is faster than reading from the server (over the network).
- This could also impact scalability positively as the
- number of calls to the server are reduced. However, local
- caching is not suitable for all workloads for e.g. read-once
- type workloads. So, you need to consider carefully your
- workload/scenario before using this option. Currently, local
- disk caching is functional for CIFS files opened as read-only.
- dir_mode If CIFS Unix extensions are not supported by the server
- this overrides the default mode for directory inodes.
- port attempt to contact the server on this tcp port, before
- trying the usual ports (port 445, then 139).
- iocharset Codepage used to convert local path names to and from
- Unicode. Unicode is used by default for network path
- names if the server supports it. If iocharset is
- not specified then the nls_default specified
- during the local client kernel build will be used.
- If server does not support Unicode, this parameter is
- unused.
- rsize default read size (usually 16K). The client currently
- can not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize
- defaults to 16K and may be changed (from 8K to the maximum
- kmalloc size allowed by your kernel) at module install time
- for cifs.ko. Setting CIFSMaxBufSize to a very large value
- will cause cifs to use more memory and may reduce performance
- in some cases. To use rsize greater than 127K (the original
- cifs protocol maximum) also requires that the server support
- a new Unix Capability flag (for very large read) which some
- newer servers (e.g. Samba 3.0.26 or later) do. rsize can be
- set from a minimum of 2048 to a maximum of 130048 (127K or
- CIFSMaxBufSize, whichever is smaller)
- wsize default write size (default 57344)
- maximum wsize currently allowed by CIFS is 57344 (fourteen
- 4096 byte pages)
- actimeo=n attribute cache timeout in seconds (default 1 second).
- After this timeout, the cifs client requests fresh attribute
- information from the server. This option allows to tune the
- attribute cache timeout to suit the workload needs. Shorter
- timeouts mean better the cache coherency, but increased number
- of calls to the server. Longer timeouts mean reduced number
- of calls to the server at the expense of less stricter cache
- coherency checks (i.e. incorrect attribute cache for a short
- period of time).
- rw mount the network share read-write (note that the
- server may still consider the share read-only)
- ro mount network share read-only
- version used to distinguish different versions of the
- mount helper utility (not typically needed)
- sep if first mount option (after the -o), overrides
- the comma as the separator between the mount
- parms. e.g.
- -o user=myname,password=mypassword,domain=mydom
- could be passed instead with period as the separator by
- -o sep=.user=myname.password=mypassword.domain=mydom
- this might be useful when comma is contained within username
- or password or domain. This option is less important
- when the cifs mount helper cifs.mount (version 1.1 or later)
- is used.
- nosuid Do not allow remote executables with the suid bit
- program to be executed. This is only meaningful for mounts
- to servers such as Samba which support the CIFS Unix Extensions.
- If you do not trust the servers in your network (your mount
- targets) it is recommended that you specify this option for
- greater security.
- exec Permit execution of binaries on the mount.
- noexec Do not permit execution of binaries on the mount.
- dev Recognize block devices on the remote mount.
- nodev Do not recognize devices on the remote mount.
- suid Allow remote files on this mountpoint with suid enabled to
- be executed (default for mounts when executed as root,
- nosuid is default for user mounts).
- credentials Although ignored by the cifs kernel component, it is used by
- the mount helper, mount.cifs. When mount.cifs is installed it
- opens and reads the credential file specified in order
- to obtain the userid and password arguments which are passed to
- the cifs vfs.
- guest Although ignored by the kernel component, the mount.cifs
- mount helper will not prompt the user for a password
- if guest is specified on the mount options. If no
- password is specified a null password will be used.
- perm Client does permission checks (vfs_permission check of uid
- and gid of the file against the mode and desired operation),
- Note that this is in addition to the normal ACL check on the
- target machine done by the server software.
- Client permission checking is enabled by default.
- noperm Client does not do permission checks. This can expose
- files on this mount to access by other users on the local
- client system. It is typically only needed when the server
- supports the CIFS Unix Extensions but the UIDs/GIDs on the
- client and server system do not match closely enough to allow
- access by the user doing the mount, but it may be useful with
- non CIFS Unix Extension mounts for cases in which the default
- mode is specified on the mount but is not to be enforced on the
- client (e.g. perhaps when MultiUserMount is enabled)
- Note that this does not affect the normal ACL check on the
- target machine done by the server software (of the server
- ACL against the user name provided at mount time).
- serverino Use server's inode numbers instead of generating automatically
- incrementing inode numbers on the client. Although this will
- make it easier to spot hardlinked files (as they will have
- the same inode numbers) and inode numbers may be persistent,
- note that the server does not guarantee that the inode numbers
- are unique if multiple server side mounts are exported under a
- single share (since inode numbers on the servers might not
- be unique if multiple filesystems are mounted under the same
- shared higher level directory). Note that some older
- (e.g. pre-Windows 2000) do not support returning UniqueIDs
- or the CIFS Unix Extensions equivalent and for those
- this mount option will have no effect. Exporting cifs mounts
- under nfsd requires this mount option on the cifs mount.
- This is now the default if server supports the
- required network operation.
- noserverino Client generates inode numbers (rather than using the actual one
- from the server). These inode numbers will vary after
- unmount or reboot which can confuse some applications,
- but not all server filesystems support unique inode
- numbers.
- setuids If the CIFS Unix extensions are negotiated with the server
- the client will attempt to set the effective uid and gid of
- the local process on newly created files, directories, and
- devices (create, mkdir, mknod). If the CIFS Unix Extensions
- are not negotiated, for newly created files and directories
- instead of using the default uid and gid specified on
- the mount, cache the new file's uid and gid locally which means
- that the uid for the file can change when the inode is
- reloaded (or the user remounts the share).
- nosetuids The client will not attempt to set the uid and gid on
- on newly created files, directories, and devices (create,
- mkdir, mknod) which will result in the server setting the
- uid and gid to the default (usually the server uid of the
- user who mounted the share). Letting the server (rather than
- the client) set the uid and gid is the default. If the CIFS
- Unix Extensions are not negotiated then the uid and gid for
- new files will appear to be the uid (gid) of the mounter or the
- uid (gid) parameter specified on the mount.
- netbiosname When mounting to servers via port 139, specifies the RFC1001
- source name to use to represent the client netbios machine
- name when doing the RFC1001 netbios session initialize.
- direct Do not do inode data caching on files opened on this mount.
- This precludes mmapping files on this mount. In some cases
- with fast networks and little or no caching benefits on the
- client (e.g. when the application is doing large sequential
- reads bigger than page size without rereading the same data)
- this can provide better performance than the default
- behavior which caches reads (readahead) and writes
- (writebehind) through the local Linux client pagecache
- if oplock (caching token) is granted and held. Note that
- direct allows write operations larger than page size
- to be sent to the server.
- strictcache Use for switching on strict cache mode. In this mode the
- client read from the cache all the time it has Oplock Level II,
- otherwise - read from the server. All written data are stored
- in the cache, but if the client doesn't have Exclusive Oplock,
- it writes the data to the server.
- rwpidforward Forward pid of a process who opened a file to any read or write
- operation on that file. This prevent applications like WINE
- from failing on read and write if we use mandatory brlock style.
- acl Allow setfacl and getfacl to manage posix ACLs if server
- supports them. (default)
- noacl Do not allow setfacl and getfacl calls on this mount
- user_xattr Allow getting and setting user xattrs (those attributes whose
- name begins with "user." or "os2.") as OS/2 EAs (extended
- attributes) to the server. This allows support of the
- setfattr and getfattr utilities. (default)
- nouser_xattr Do not allow getfattr/setfattr to get/set/list xattrs
- mapchars Translate six of the seven reserved characters (not backslash)
- *?<>|:
- to the remap range (above 0xF000), which also
- allows the CIFS client to recognize files created with
- such characters by Windows's POSIX emulation. This can
- also be useful when mounting to most versions of Samba
- (which also forbids creating and opening files
- whose names contain any of these seven characters).
- This has no effect if the server does not support
- Unicode on the wire.
- nomapchars Do not translate any of these seven characters (default).
- nocase Request case insensitive path name matching (case
- sensitive is the default if the server supports it).
- (mount option "ignorecase" is identical to "nocase")
- posixpaths If CIFS Unix extensions are supported, attempt to
- negotiate posix path name support which allows certain
- characters forbidden in typical CIFS filenames, without
- requiring remapping. (default)
- noposixpaths If CIFS Unix extensions are supported, do not request
- posix path name support (this may cause servers to
- reject creatingfile with certain reserved characters).
- nounix Disable the CIFS Unix Extensions for this mount (tree
- connection). This is rarely needed, but it may be useful
- in order to turn off multiple settings all at once (ie
- posix acls, posix locks, posix paths, symlink support
- and retrieving uids/gids/mode from the server) or to
- work around a bug in server which implement the Unix
- Extensions.
- nobrl Do not send byte range lock requests to the server.
- This is necessary for certain applications that break
- with cifs style mandatory byte range locks (and most
- cifs servers do not yet support requesting advisory
- byte range locks).
- forcemandatorylock Even if the server supports posix (advisory) byte range
- locking, send only mandatory lock requests. For some
- (presumably rare) applications, originally coded for
- DOS/Windows, which require Windows style mandatory byte range
- locking, they may be able to take advantage of this option,
- forcing the cifs client to only send mandatory locks
- even if the cifs server would support posix advisory locks.
- "forcemand" is accepted as a shorter form of this mount
- option.
- nostrictsync If this mount option is set, when an application does an
- fsync call then the cifs client does not send an SMB Flush
- to the server (to force the server to write all dirty data
- for this file immediately to disk), although cifs still sends
- all dirty (cached) file data to the server and waits for the
- server to respond to the write. Since SMB Flush can be
- very slow, and some servers may be reliable enough (to risk
- delaying slightly flushing the data to disk on the server),
- turning on this option may be useful to improve performance for
- applications that fsync too much, at a small risk of server
- crash. If this mount option is not set, by default cifs will
- send an SMB flush request (and wait for a response) on every
- fsync call.
- nodfs Disable DFS (global name space support) even if the
- server claims to support it. This can help work around
- a problem with parsing of DFS paths with Samba server
- versions 3.0.24 and 3.0.25.
- remount remount the share (often used to change from ro to rw mounts
- or vice versa)
- cifsacl Report mode bits (e.g. on stat) based on the Windows ACL for
- the file. (EXPERIMENTAL)
- servern Specify the server 's netbios name (RFC1001 name) to use
- when attempting to setup a session to the server.
- This is needed for mounting to some older servers (such
- as OS/2 or Windows 98 and Windows ME) since they do not
- support a default server name. A server name can be up
- to 15 characters long and is usually uppercased.
- sfu When the CIFS Unix Extensions are not negotiated, attempt to
- create device files and fifos in a format compatible with
- Services for Unix (SFU). In addition retrieve bits 10-12
- of the mode via the SETFILEBITS extended attribute (as
- SFU does). In the future the bottom 9 bits of the
- mode also will be emulated using queries of the security
- descriptor (ACL).
- mfsymlinks Enable support for Minshall+French symlinks
- (see http://wiki.samba.org/index.php/UNIX_Extensions#Minshall.2BFrench_symlinks)
- This option is ignored when specified together with the
- 'sfu' option. Minshall+French symlinks are used even if
- the server supports the CIFS Unix Extensions.
- sign Must use packet signing (helps avoid unwanted data modification
- by intermediate systems in the route). Note that signing
- does not work with lanman or plaintext authentication.
- seal Must seal (encrypt) all data on this mounted share before
- sending on the network. Requires support for Unix Extensions.
- Note that this differs from the sign mount option in that it
- causes encryption of data sent over this mounted share but other
- shares mounted to the same server are unaffected.
- locallease This option is rarely needed. Fcntl F_SETLEASE is
- used by some applications such as Samba and NFSv4 server to
- check to see whether a file is cacheable. CIFS has no way
- to explicitly request a lease, but can check whether a file
- is cacheable (oplocked). Unfortunately, even if a file
- is not oplocked, it could still be cacheable (ie cifs client
- could grant fcntl leases if no other local processes are using
- the file) for cases for example such as when the server does not
- support oplocks and the user is sure that the only updates to
- the file will be from this client. Specifying this mount option
- will allow the cifs client to check for leases (only) locally
- for files which are not oplocked instead of denying leases
- in that case. (EXPERIMENTAL)
- sec Security mode. Allowed values are:
- none attempt to connection as a null user (no name)
- krb5 Use Kerberos version 5 authentication
- krb5i Use Kerberos authentication and packet signing
- ntlm Use NTLM password hashing (default)
- ntlmi Use NTLM password hashing with signing (if
- /proc/fs/cifs/PacketSigningEnabled on or if
- server requires signing also can be the default)
- ntlmv2 Use NTLMv2 password hashing
- ntlmv2i Use NTLMv2 password hashing with packet signing
- lanman (if configured in kernel config) use older
- lanman hash
-hard Retry file operations if server is not responding
-soft Limit retries to unresponsive servers (usually only
- one retry) before returning an error. (default)
-
-The mount.cifs mount helper also accepts a few mount options before -o
-including:
-
- -S take password from stdin (equivalent to setting the environment
- variable "PASSWD_FD=0"
- -V print mount.cifs version
- -? display simple usage information
-
-With most 2.6 kernel versions of modutils, the version of the cifs kernel
-module can be displayed via modinfo.
-
-Misc /proc/fs/cifs Flags and Debug Info
-=======================================
-Informational pseudo-files:
-DebugData Displays information about active CIFS sessions and
- shares, features enabled as well as the cifs.ko
- version.
-Stats Lists summary resource usage information as well as per
- share statistics, if CONFIG_CIFS_STATS in enabled
- in the kernel configuration.
-
-Configuration pseudo-files:
-PacketSigningEnabled If set to one, cifs packet signing is enabled
- and will be used if the server requires
- it. If set to two, cifs packet signing is
- required even if the server considers packet
- signing optional. (default 1)
-SecurityFlags Flags which control security negotiation and
- also packet signing. Authentication (may/must)
- flags (e.g. for NTLM and/or NTLMv2) may be combined with
- the signing flags. Specifying two different password
- hashing mechanisms (as "must use") on the other hand
- does not make much sense. Default flags are
- 0x07007
- (NTLM, NTLMv2 and packet signing allowed). The maximum
- allowable flags if you want to allow mounts to servers
- using weaker password hashes is 0x37037 (lanman,
- plaintext, ntlm, ntlmv2, signing allowed). Some
- SecurityFlags require the corresponding menuconfig
- options to be enabled (lanman and plaintext require
- CONFIG_CIFS_WEAK_PW_HASH for example). Enabling
- plaintext authentication currently requires also
- enabling lanman authentication in the security flags
- because the cifs module only supports sending
- laintext passwords using the older lanman dialect
- form of the session setup SMB. (e.g. for authentication
- using plain text passwords, set the SecurityFlags
- to 0x30030):
-
- may use packet signing 0x00001
- must use packet signing 0x01001
- may use NTLM (most common password hash) 0x00002
- must use NTLM 0x02002
- may use NTLMv2 0x00004
- must use NTLMv2 0x04004
- may use Kerberos security 0x00008
- must use Kerberos 0x08008
- may use lanman (weak) password hash 0x00010
- must use lanman password hash 0x10010
- may use plaintext passwords 0x00020
- must use plaintext passwords 0x20020
- (reserved for future packet encryption) 0x00040
-
-cifsFYI If set to non-zero value, additional debug information
- will be logged to the system error log. This field
- contains three flags controlling different classes of
- debugging entries. The maximum value it can be set
- to is 7 which enables all debugging points (default 0).
- Some debugging statements are not compiled into the
- cifs kernel unless CONFIG_CIFS_DEBUG2 is enabled in the
- kernel configuration. cifsFYI may be set to one or
- nore of the following flags (7 sets them all):
-
- log cifs informational messages 0x01
- log return codes from cifs entry points 0x02
- log slow responses (ie which take longer than 1 second)
- CONFIG_CIFS_STATS2 must be enabled in .config 0x04
-
-
-traceSMB If set to one, debug information is logged to the
- system error log with the start of smb requests
- and responses (default 0)
-LookupCacheEnable If set to one, inode information is kept cached
- for one second improving performance of lookups
- (default 1)
-OplockEnabled If set to one, safe distributed caching enabled.
- (default 1)
-LinuxExtensionsEnabled If set to one then the client will attempt to
- use the CIFS "UNIX" extensions which are optional
- protocol enhancements that allow CIFS servers
- to return accurate UID/GID information as well
- as support symbolic links. If you use servers
- such as Samba that support the CIFS Unix
- extensions but do not want to use symbolic link
- support and want to map the uid and gid fields
- to values supplied at mount (rather than the
- actual values, then set this to zero. (default 1)
-
-These experimental features and tracing can be enabled by changing flags in
-/proc/fs/cifs (after the cifs module has been installed or built into the
-kernel, e.g. insmod cifs). To enable a feature set it to 1 e.g. to enable
-tracing to the kernel message log type:
-
- echo 7 > /proc/fs/cifs/cifsFYI
-
-cifsFYI functions as a bit mask. Setting it to 1 enables additional kernel
-logging of various informational messages. 2 enables logging of non-zero
-SMB return codes while 4 enables logging of requests that take longer
-than one second to complete (except for byte range lock requests).
-Setting it to 4 requires defining CONFIG_CIFS_STATS2 manually in the
-source code (typically by setting it in the beginning of cifsglob.h),
-and setting it to seven enables all three. Finally, tracing
-the start of smb requests and responses can be enabled via:
-
- echo 1 > /proc/fs/cifs/traceSMB
-
-Per share (per client mount) statistics are available in /proc/fs/cifs/Stats
-if the kernel was configured with cifs statistics enabled. The statistics
-represent the number of successful (ie non-zero return code from the server)
-SMB responses to some of the more common commands (open, delete, mkdir etc.).
-Also recorded is the total bytes read and bytes written to the server for
-that share. Note that due to client caching effects this can be less than the
-number of bytes read and written by the application running on the client.
-The statistics for the number of total SMBs and oplock breaks are different in
-that they represent all for that share, not just those for which the server
-returned success.
-
-Also note that "cat /proc/fs/cifs/DebugData" will display information about
-the active sessions and the shares that are mounted.
-
-Enabling Kerberos (extended security) works but requires version 1.2 or later
-of the helper program cifs.upcall to be present and to be configured in the
-/etc/request-key.conf file. The cifs.upcall helper program is from the Samba
-project(http://www.samba.org). NTLM and NTLMv2 and LANMAN support do not
-require this helper. Note that NTLMv2 security (which does not require the
-cifs.upcall helper program), instead of using Kerberos, is sufficient for
-some use cases.
-
-DFS support allows transparent redirection to shares in an MS-DFS name space.
-In addition, DFS support for target shares which are specified as UNC
-names which begin with host names (rather than IP addresses) requires
-a user space helper (such as cifs.upcall) to be present in order to
-translate host names to ip address, and the user space helper must also
-be configured in the file /etc/request-key.conf. Samba, Windows servers and
-many NAS appliances support DFS as a way of constructing a global name
-space to ease network configuration and improve reliability.
-
-To use cifs Kerberos and DFS support, the Linux keyutils package should be
-installed and something like the following lines should be added to the
-/etc/request-key.conf file:
-
-create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
-create dns_resolver * * /usr/local/sbin/cifs.upcall %k
-
-CIFS kernel module parameters
-=============================
-These module parameters can be specified or modified either during the time of
-module loading or during the runtime by using the interface
- /proc/module/cifs/parameters/<param>
-
-i.e. echo "value" > /sys/module/cifs/parameters/<param>
-
-1. enable_oplocks - Enable or disable oplocks. Oplocks are enabled by default.
- [Y/y/1]. To disable use any of [N/n/0].
-