1# SPDX-License-Identifier: GPL-2.0-only
2config CIFS
3	tristate "SMB3 and CIFS support (advanced network filesystem)"
4	depends on INET
5	select NLS
6	select CRYPTO
7	select CRYPTO_MD4
8	select CRYPTO_MD5
9	select CRYPTO_SHA256
10	select CRYPTO_SHA512
11	select CRYPTO_CMAC
12	select CRYPTO_HMAC
13	select CRYPTO_LIB_ARC4
14	select CRYPTO_AEAD2
15	select CRYPTO_CCM
16	select CRYPTO_GCM
17	select CRYPTO_ECB
18	select CRYPTO_AES
19	select CRYPTO_LIB_DES
20	select KEYS
21	help
22	  This is the client VFS module for the SMB3 family of NAS protocols,
23	  (including support for the most recent, most secure dialect SMB3.1.1)
24	  as well as for earlier dialects such as SMB2.1, SMB2 and the older
25	  Common Internet File System (CIFS) protocol.  CIFS was the successor
26	  to the original dialect, the Server Message Block (SMB) protocol, the
27	  native file sharing mechanism for most early PC operating systems.
28
29	  The SMB3 protocol is supported by most modern operating systems
30	  and NAS appliances (e.g. Samba, Windows 10, Windows Server 2016,
31	  MacOS) and even in the cloud (e.g. Microsoft Azure).
32	  The older CIFS protocol was included in Windows NT4, 2000 and XP (and
33	  later) as well by Samba (which provides excellent CIFS and SMB3
34	  server support for Linux and many other operating systems). Use of
35	  dialects older than SMB2.1 is often discouraged on public networks.
36	  This module also provides limited support for OS/2 and Windows ME
37	  and similar very old servers.
38
39	  This module provides an advanced network file system client
40	  for mounting to SMB3 (and CIFS) compliant servers.  It includes
41	  support for DFS (hierarchical name space), secure per-user
42	  session establishment via Kerberos or NTLM or NTLMv2, RDMA
43	  (smbdirect), advanced security features, per-share encryption,
44	  directory leases, safe distributed caching (oplock), optional packet
45	  signing, Unicode and other internationalization improvements.
46
47	  In general, the default dialects, SMB3 and later, enable better
48	  performance, security and features, than would be possible with CIFS.
49	  Note that when mounting to Samba, due to the CIFS POSIX extensions,
50	  CIFS mounts can provide slightly better POSIX compatibility
51	  than SMB3 mounts. SMB2/SMB3 mount options are also
52	  slightly simpler (compared to CIFS) due to protocol improvements.
53
54	  If you need to mount to Samba, Azure, Macs or Windows from this machine, say Y.
55
56config CIFS_STATS2
57	bool "Extended statistics"
58	depends on CIFS
59	help
60	  Enabling this option will allow more detailed statistics on SMB
61	  request timing to be displayed in /proc/fs/cifs/DebugData and also
62	  allow optional logging of slow responses to dmesg (depending on the
63	  value of /proc/fs/cifs/cifsFYI, see fs/cifs/README for more details).
64	  These additional statistics may have a minor effect on performance
65	  and memory utilization.
66
67	  Unless you are a developer or are doing network performance analysis
68	  or tuning, say N.
69
70config CIFS_ALLOW_INSECURE_LEGACY
71	bool "Support legacy servers which use less secure dialects"
72	depends on CIFS
73	default y
74	help
75	  Modern dialects, SMB2.1 and later (including SMB3 and 3.1.1), have
76	  additional security features, including protection against
77	  man-in-the-middle attacks and stronger crypto hashes, so the use
78	  of legacy dialects (SMB1/CIFS and SMB2.0) is discouraged.
79
80	  Disabling this option prevents users from using vers=1.0 or vers=2.0
81	  on mounts with cifs.ko
82
83	  If unsure, say Y.
84
85config CIFS_WEAK_PW_HASH
86	bool "Support legacy servers which use weaker LANMAN security"
87	depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY
88	help
89	  Modern CIFS servers including Samba and most Windows versions
90	  (since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
91	  security mechanisms. These hash the password more securely
92	  than the mechanisms used in the older LANMAN version of the
93	  SMB protocol but LANMAN based authentication is needed to
94	  establish sessions with some old SMB servers.
95
96	  Enabling this option allows the cifs module to mount to older
97	  LANMAN based servers such as OS/2 and Windows 95, but such
98	  mounts may be less secure than mounts using NTLM or more recent
99	  security mechanisms if you are on a public network.  Unless you
100	  have a need to access old SMB servers (and are on a private
101	  network) you probably want to say N.  Even if this support
102	  is enabled in the kernel build, LANMAN authentication will not be
103	  used automatically. At runtime LANMAN mounts are disabled but
104	  can be set to required (or optional) either in
105	  /proc/fs/cifs (see fs/cifs/README for more detail) or via an
106	  option on the mount command. This support is disabled by
107	  default in order to reduce the possibility of a downgrade
108	  attack.
109
110	  If unsure, say N.
111
112config CIFS_UPCALL
113	bool "Kerberos/SPNEGO advanced session setup"
114	depends on CIFS
115	select DNS_RESOLVER
116	help
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.
121
122config CIFS_XATTR
123	bool "CIFS extended attributes"
124	depends on CIFS
125	help
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.
134
135	  If unsure, say Y.
136
137config CIFS_POSIX
138	bool "CIFS POSIX Extensions"
139	depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY && CIFS_XATTR
140	help
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.
148
149config CIFS_DEBUG
150	bool "Enable CIFS debugging routines"
151	default y
152	depends on CIFS
153	help
154	  Enabling this option adds helpful debugging messages to
155	  the cifs code which increases the size of the cifs module.
156	  If unsure, say Y.
157
158config CIFS_DEBUG2
159	bool "Enable additional CIFS debugging routines"
160	depends on CIFS_DEBUG
161	help
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.
168
169config CIFS_DEBUG_DUMP_KEYS
170	bool "Dump encryption keys for offline decryption (Unsafe)"
171	depends on CIFS_DEBUG
172	help
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.
177	  If unsure, say N.
178
179config CIFS_DFS_UPCALL
180	bool "DFS feature support"
181	depends on CIFS
182	select DNS_RESOLVER
183	help
184	  Distributed File System (DFS) support is used to access shares
185	  transparently in an enterprise name space, even if the share
186	  moves to a different server.  This feature also enables
187	  an upcall mechanism for CIFS which contacts userspace helper
188	  utilities to provide server name resolution (host names to
189	  IP addresses) which is needed in order to reconnect to
190	  servers if their addresses change or for implicit mounts of
191	  DFS junction points. If unsure, say Y.
192
193config CIFS_NFSD_EXPORT
194	bool "Allow nfsd to export CIFS file system"
195	depends on CIFS && BROKEN
196	help
197	  Allows NFS server to export a CIFS mounted share (nfsd over cifs)
198
199config CIFS_SMB_DIRECT
200	bool "SMB Direct support"
201	depends on CIFS=m && INFINIBAND && INFINIBAND_ADDR_TRANS || CIFS=y && INFINIBAND=y && INFINIBAND_ADDR_TRANS=y
202	help
203	  Enables SMB Direct support for SMB 3.0, 3.02 and 3.1.1.
204	  SMB Direct allows transferring SMB packets over RDMA. If unsure,
205	  say N.
206
207config CIFS_FSCACHE
208	bool "Provide CIFS client caching support"
209	depends on CIFS=m && FSCACHE || CIFS=y && FSCACHE=y
210	help
211	  Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
212	  to be cached locally on disk through the general filesystem cache
213	  manager. If unsure, say N.
214
215config CIFS_ROOT
216	bool "SMB root file system (Experimental)"
217	depends on CIFS=y && IP_PNP
218	help
219	  Enables root file system support over SMB protocol.
220
221	  Most people say N here.
222