1 # SPDX-License-Identifier: GPL-2.0-only
3 tristate "SMB3 and CIFS support (advanced network filesystem)"
13 select CRYPTO_LIB_ARC4
23 This is the client VFS module for the SMB3 family of NAS protocols,
24 (including support for the most recent, most secure dialect SMB3.1.1)
25 as well as for earlier dialects such as SMB2.1, SMB2 and the older
26 Common Internet File System (CIFS) protocol. CIFS was the successor
27 to the original dialect, the Server Message Block (SMB) protocol, the
28 native file sharing mechanism for most early PC operating systems.
30 The SMB3 protocol is supported by most modern operating systems
31 and NAS appliances (e.g. Samba, Windows 10, Windows Server 2016,
32 MacOS) and even in the cloud (e.g. Microsoft Azure).
33 The older CIFS protocol was included in Windows NT4, 2000 and XP (and
34 later) as well by Samba (which provides excellent CIFS and SMB3
35 server support for Linux and many other operating systems). Use of
36 dialects older than SMB2.1 is often discouraged on public networks.
37 This module also provides limited support for OS/2 and Windows ME
38 and similar very old servers.
40 This module provides an advanced network file system client
41 for mounting to SMB3 (and CIFS) compliant servers. It includes
42 support for DFS (hierarchical name space), secure per-user
43 session establishment via Kerberos or NTLM or NTLMv2, RDMA
44 (smbdirect), advanced security features, per-share encryption,
45 directory leases, safe distributed caching (oplock), optional packet
46 signing, Unicode and other internationalization improvements.
48 In general, the default dialects, SMB3 and later, enable better
49 performance, security and features, than would be possible with CIFS.
50 Note that when mounting to Samba, due to the CIFS POSIX extensions,
51 CIFS mounts can provide slightly better POSIX compatibility
52 than SMB3 mounts. SMB2/SMB3 mount options are also
53 slightly simpler (compared to CIFS) due to protocol improvements.
55 If you need to mount to Samba, Azure, Macs or Windows from this machine, say Y.
58 bool "Extended statistics"
61 Enabling this option will allow more detailed statistics on SMB
62 request timing to be displayed in /proc/fs/cifs/DebugData and also
63 allow optional logging of slow responses to dmesg (depending on the
64 value of /proc/fs/cifs/cifsFYI). See Documentation/admin-guide/cifs/usage.rst
65 for more details. These additional statistics may have a minor effect
66 on performance and memory utilization.
68 Unless you are a developer or are doing network performance analysis
71 config CIFS_ALLOW_INSECURE_LEGACY
72 bool "Support legacy servers which use less secure dialects"
76 Modern dialects, SMB2.1 and later (including SMB3 and 3.1.1), have
77 additional security features, including protection against
78 man-in-the-middle attacks and stronger crypto hashes, so the use
79 of legacy dialects (SMB1/CIFS and SMB2.0) is discouraged.
81 Disabling this option prevents users from using vers=1.0 or vers=2.0
82 on mounts with cifs.ko
86 config CIFS_WEAK_PW_HASH
87 bool "Support legacy servers which use weaker LANMAN security"
88 depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY
90 Modern CIFS servers including Samba and most Windows versions
91 (since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
92 security mechanisms. These hash the password more securely
93 than the mechanisms used in the older LANMAN version of the
94 SMB protocol but LANMAN based authentication is needed to
95 establish sessions with some old SMB servers.
97 Enabling this option allows the cifs module to mount to older
98 LANMAN based servers such as OS/2 and Windows 95, but such
99 mounts may be less secure than mounts using NTLM or more recent
100 security mechanisms if you are on a public network. Unless you
101 have a need to access old SMB servers (and are on a private
102 network) you probably want to say N. Even if this support
103 is enabled in the kernel build, LANMAN authentication will not be
104 used automatically. At runtime LANMAN mounts are disabled but
105 can be set to required (or optional) either in
106 /proc/fs/cifs (see Documentation/admin-guide/cifs/usage.rst for
107 more detail) or via an option on the mount command. This support
108 is disabled by default in order to reduce the possibility of a
114 bool "Kerberos/SPNEGO advanced session setup"
117 Enables an upcall mechanism for CIFS which accesses userspace helper
118 utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
119 which are needed to mount to certain secure servers (for which more
120 secure Kerberos authentication is required). If unsure, say Y.
123 bool "CIFS extended attributes"
126 Extended attributes are name:value pairs associated with inodes by
127 the kernel or by users (see the attr(5) manual page for details).
128 CIFS maps the name of extended attributes beginning with the user
129 namespace prefix to SMB/CIFS EAs. EAs are stored on Windows
130 servers without the user namespace prefix, but their names are
131 seen by Linux cifs clients prefaced by the user namespace prefix.
132 The system namespace (used by some filesystems to store ACLs) is
133 not supported at this time.
138 bool "CIFS POSIX Extensions"
139 depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY && CIFS_XATTR
141 Enabling this option will cause the cifs client to attempt to
142 negotiate a newer dialect with servers, such as Samba 3.0.5
143 or later, that optionally can handle more POSIX like (rather
144 than Windows like) file behavior. It also enables
145 support for POSIX ACLs (getfacl and setfacl) to servers
146 (such as Samba 3.10 and later) which can negotiate
147 CIFS POSIX ACL support. If unsure, say N.
150 bool "Enable CIFS debugging routines"
154 Enabling this option adds helpful debugging messages to
155 the cifs code which increases the size of the cifs module.
159 bool "Enable additional CIFS debugging routines"
160 depends on CIFS_DEBUG
162 Enabling this option adds a few more debugging routines
163 to the cifs code which slightly increases the size of
164 the cifs module and can cause additional logging of debug
165 messages in some error paths, slowing performance. This
166 option can be turned off unless you are debugging
167 cifs problems. If unsure, say N.
169 config CIFS_DEBUG_DUMP_KEYS
170 bool "Dump encryption keys for offline decryption (Unsafe)"
171 depends on CIFS_DEBUG
173 Enabling this will dump the encryption and decryption keys
174 used to communicate on an encrypted share connection on the
175 console. This allows Wireshark to decrypt and dissect
176 encrypted network captures. Enable this carefully.
179 config CIFS_DFS_UPCALL
180 bool "DFS feature support"
183 Distributed File System (DFS) support is used to access shares
184 transparently in an enterprise name space, even if the share
185 moves to a different server. This feature also enables
186 an upcall mechanism for CIFS which contacts userspace helper
187 utilities to provide server name resolution (host names to
188 IP addresses) which is needed in order to reconnect to
189 servers if their addresses change or for implicit mounts of
190 DFS junction points. If unsure, say Y.
192 config CIFS_SWN_UPCALL
193 bool "SWN feature support"
196 The Service Witness Protocol (SWN) is used to get notifications
197 from a highly available server of resource state changes. This
198 feature enables an upcall mechanism for CIFS which contacts a
199 userspace daemon to establish the DCE/RPC connection to retrieve
200 the cluster available interfaces and resource change notifications.
203 config CIFS_NFSD_EXPORT
204 bool "Allow nfsd to export CIFS file system"
205 depends on CIFS && BROKEN
207 Allows NFS server to export a CIFS mounted share (nfsd over cifs)
209 config CIFS_SMB_DIRECT
210 bool "SMB Direct support"
211 depends on CIFS=m && INFINIBAND && INFINIBAND_ADDR_TRANS || CIFS=y && INFINIBAND=y && INFINIBAND_ADDR_TRANS=y
213 Enables SMB Direct support for SMB 3.0, 3.02 and 3.1.1.
214 SMB Direct allows transferring SMB packets over RDMA. If unsure,
218 bool "Provide CIFS client caching support"
219 depends on CIFS=m && FSCACHE || CIFS=y && FSCACHE=y
221 Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
222 to be cached locally on disk through the general filesystem cache
223 manager. If unsure, say N.
226 bool "SMB root file system (Experimental)"
227 depends on CIFS=y && IP_PNP
229 Enables root file system support over SMB protocol.
231 Most people say N here.