fs/cifs/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 config 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
  56 config 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
  70 config 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
  85 config 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
 112 config 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
 122 config 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
 137 config 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
 149 config 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
 158 config 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
 169 config 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
 179 config 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
 193 config 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
 199 config 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 Y.
 206
 207 config 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
 215 config 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.