5) make dep
6) make modules (or "make" if CIFS VFS not to be built as a module)
-For Linux 2.5:
-1) Download the kernel (e.g. from http://www.kernel.org or from bitkeeper
-at bk://linux.bkbits.net/linux-2.5) and change directory into the top
-of the kernel directory tree (e.g. /usr/src/linux-2.5.73)
+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
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
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.
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
delete readonly = yes
ea support = yes
-Note that ea support is required for supporting Linux xattrs.
-Some administrators also change the "map archive" and the "create mask"
-parameters from their default values. Creating special devices (mknod) remotely
-may require specifying a mkdev function to Samba. 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
+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 3.0.5, most symlinks to
+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 3.0.5 server or later includes the ability to create
+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
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:
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.
+problem as most servers support this. IPv6 support is planned for the future,
+and is almost complete.
+
+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
======================
(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 as long as the inode remains in
+ (gid) is cached as long as the inode remains in
memory on the client. Also note that permission
checks (authorization checks) on accesses to a file occur
at the server, but there are cases in which an administrator
(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
+ 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.
gid If CIFS Unix extensions are not supported by the server
this overrides the default gid for inodes.
file_mode If CIFS Unix extensions are not supported by the server
during the local client kernel build will be used.
If server does not support Unicode, this parameter is
unused.
- rsize default read size
- wsize default write size
+ rsize default read size (usually 16K)
+ wsize default write size (usually 16K, 32K is often better over GigE)
+ maximum wsize currently allowed by CIFS is 57344 (14 4096 byte
+ pages)
rw mount the network share read-write (note that the
server may still consider the share read-only)
ro mount network share read-only
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).
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 servers 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 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.
+ noserverino Client generates inode numbers (rather than using the actual one
+ from the server) by default.
+ 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 mmaping 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.
+ 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.
+ 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 suports it).
+ 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).
+ 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).
+ remount remount the share (often used to change from ro to rw mounts
+ or vice versa)
+ 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).
+ 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.
+ 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
The mount.cifs mount helper also accepts a few mount options before -o
including:
=======================================
Informational pseudo-files:
DebugData Displays information about active CIFS sessions
- and shares.
-SimultaneousOps Counter which holds maximum number of
- simultaneous outstanding SMB/CIFS requests.
+ and shares, 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.
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). Maximum
+ allowable flags if you want to allow mounts to servers
+ using weaker password hashes is 0x37037 (lanman,
+ plaintext, ntlm, ntlmv2, signing allowed):
+
+ 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 (not implemented yet) 0x00008
+ must use Kerberos (not implemented yet) 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 one, additional debug information is
logged to the system error log. (default 0)
-ExtendedSecurity If set to one, SPNEGO session establishment
- is allowed which enables more advanced
- secure CIFS session establishment (default 0)
-NTLMV2Enabled If set to one, more secure password hashes
- are used when the server supports them and
- when kerberos is not negotiated (default 0)
traceSMB If set to one, debug information is logged to the
system error log with the start of smb requests
and responses (default 0)
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)
+Experimental When set to 1 used to enable certain experimental
+ features (currently enables multipage writes
+ when signing is enabled, the multipage write
+ 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).
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 1 > /proc/fs/cifs/cifsFYI
+ echo 7 > /proc/fs/cifs/cifsFYI
-and for more extensive tracing including the start of smb requests and responses
+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
-Three other experimental features are under development and to test
-require enabling an ifdef (e.g. by adding "#define CIFS_FCNTL" in cifsglob.h)
-
- CONFIG_CIFS_QUOTA
+Two other experimental features are under development and to test
+require enabling CONFIG_CIFS_EXPERIMENTAL
- CONFIG_CIFS_XATTR
+ More efficient write operations
- CONFIG_CIFS_FCNTL (fcntl needed for support of directory change
+ DNOTIFY fcntl: needed for support of directory change
notification and perhaps later for file leases)
-Per share (per client mount) statistics are available in /proc/fs/cifs/DebugData
+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 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 they its implementation is not quite complete yet.
-Do not alter these configuration values unless you are doing specific testing.
+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
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