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