4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Steve French <stfrench@xxxxxxxxxxxxx>
commit 7420451f6a109f7f8f1bf283f34d08eba3259fb3 upstream.
allow disabling cifs (SMB1 ie vers=1.0) and vers=2.0 in the
config for the build of cifs.ko if want to always prevent mounting
with these less secure dialects.
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
Reviewed-by: Jeremy Allison <jra@xxxxxxxxx>
Cc: Alakesh Haloi <alakeshh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/Kconfig | 17 ++++++++++++++++-
fs/cifs/connect.c | 9 +++++++++
2 files changed, 25 insertions(+), 1 deletion(-)
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -66,9 +66,24 @@ config CIFS_STATS2
Unless you are a developer or are doing network performance analysis
or tuning, say N.
+config CIFS_ALLOW_INSECURE_LEGACY
+ bool "Support legacy servers which use less secure dialects"
+ depends on CIFS
+ default y
+ help
+ Modern dialects, SMB2.1 and later (including SMB3 and 3.1.1), have
+ additional security features, including protection against
+ man-in-the-middle attacks and stronger crypto hashes, so the use
+ of legacy dialects (SMB1/CIFS and SMB2.0) is discouraged.
+
+ Disabling this option prevents users from using vers=1.0 or vers=2.0
+ on mounts with cifs.ko
+
+ If unsure, say Y.
+
config CIFS_WEAK_PW_HASH
bool "Support legacy servers which use weaker LANMAN security"
- depends on CIFS
+ depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY
help
Modern CIFS servers including Samba and most Windows versions
(since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1130,6 +1130,7 @@ cifs_parse_smb_version(char *value, stru
substring_t args[MAX_OPT_ARGS];
switch (match_token(value, cifs_smb_version_tokens, args)) {
+#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
case Smb_1:
vol->ops = &smb1_operations;
vol->vals = &smb1_values;
@@ -1138,6 +1139,14 @@ cifs_parse_smb_version(char *value, stru
vol->ops = &smb20_operations;
vol->vals = &smb20_values;
break;
+#else
+ case Smb_1:
+ cifs_dbg(VFS, "vers=1.0 (cifs) mount not permitted when legacy dialects disabled\n");
+ return 1;
+ case Smb_20:
+ cifs_dbg(VFS, "vers=2.0 mount not permitted when legacy dialects disabled\n");
+ return 1;
+#endif /* CIFS_ALLOW_INSECURE_LEGACY */
case Smb_21:
vol->ops = &smb21_operations;
vol->vals = &smb21_values;
