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.
+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)
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>
+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
Restrictions
============
-Servers must support the NTLM SMB dialect (which is the most recent, supported
-by Samba and Windows NT version 4, 2000 and XP and many other SMB/CIFS servers)
Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
-1001/1002 support for "Netbios-Over-TCP/IP." Neither of these is likely to be a
-problem as most servers support this. IPv6 support is planned for the future,
-and is almost complete.
+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 :
the CIFS session.
password The user password. If the mount helper is
installed, the user will be prompted for password
- if it is not supplied.
+ 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
- uid Set the default uid for inodes. For mounts to servers
+ 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
+ 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
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. For the uid (gid) of newly
- created files and directories, ie files created since
- the last mount of the server share, the expected uid
- (gid) is cached as long as the inode remains in
- memory on the client. Also note that permission
+ (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
(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. Note that the mount.cifs helper must be
- at version 1.10 or higher to support specifying the uid
- (or gid) in non-numberic form.
+ 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.
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 servers inode numbers instead of generating automatically
+ 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,
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 this requires that
- the server support the CIFS Unix Extensions as other servers
- do not return a unique IndexNumber on SMB FindFirst (most
- servers return zero as the IndexNumber). Parameter has no
- effect to Windows servers and others which do not support the
- CIFS Unix Extensions.
+ 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) by default.
+ 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
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 as OS/2 EAs (extended
- attributes) to the server (default) e.g. via setfattr
- and getfattr utilities.
+ 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)
*?<>|:
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 suports 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
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
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
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:
hashing mechanisms (as "must use") on the other hand
does not make much sense. Default flags are
0x07007
- (NTLM, NTLMv2 and packet signing allowed). Maximum
+ (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):
+ 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
must use NTLM 0x02002
may use NTLMv2 0x00004
must use NTLMv2 0x04004
- may use Kerberos security (not implemented yet) 0x00008
- must use Kerberos (not implemented yet) 0x08008
+ 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
performance enhancement was disabled when
signing turned on in case buffer was modified
just before it was sent, also this flag will
- be used to use the new experimental sessionsetup
- code).
+ be used to use the new experimental directory change
+ notification code). When set to 2 enables
+ an additional experimental feature, "raw ntlmssp"
+ session establishment support (which allows
+ specifying "sec=ntlmssp" on mount). The Linux cifs
+ module will use ntlmv2 authentication encapsulated
+ in "raw ntlmssp" (not using SPNEGO) when
+ "sec=ntlmssp" is specified on mount.
+ This support also requires building cifs with
+ the CONFIG_CIFS_EXPERIMENTAL configuration flag.
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
Two other experimental features are under development. To test these
requires enabling CONFIG_CIFS_EXPERIMENTAL
- ipv6 enablement
+ cifsacl support needed to retrieve approximated mode bits based on
+ the contents on the CIFS ACL.
+
+ lease support: cifs will check the oplock state before calling into
+ the vfs to see if we can grant a lease on a file.
DNOTIFY fcntl: needed for support of directory change
notification and perhaps later for file leases)
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. Note: NTLMv2 enablement
-will not work since its implementation is not quite complete yet. Do not alter
-the ExtendedSecurity configuration value unless you are doing specific testing.
-Enabling extended security works to Windows 2000 Workstations and XP but not to
-Windows 2000 server or Samba since it does not usually send "raw NTLMSSP"
-(instead it sends NTLMSSP encapsulated in SPNEGO/GSSAPI, which support is not
-complete in the CIFS VFS yet).
+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
+
+
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff