CIFS: Fix SMB3 mount without specifying a security mechanism

Commit ef65aaede23f ("smb2: Enforce sec= mount option") changed the
behavior of a mount command to enforce a specified security mechanism
during mounting. On another hand according to the spec if SMB3 server
doesn't respond with a security context it implies that it supports
NTLMSSP. The current code doesn't keep it in mind and fails a mount
for such servers if no security mechanism is specified. Fix this by
indicating that a server supports NTLMSSP if a security context isn't
returned during negotiate phase. This allows the code to use NTLMSSP
by default for SMB3 mounts.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 1bd5d3033fc83493b38524e46854aaf7ad7c0e0f..02da648041fcd58d6e37431a60d596a5bfd4ca06 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -562,8 +562,10 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
         * but for time being this is our only auth choice so doesn't matter.
         * We just found a server which sets blob length to zero expecting raw.
         */
-       if (blob_length == 0)
+       if (blob_length == 0) {
                cifs_dbg(FYI, "missing security blob on negprot\n");
+               server->sec_ntlmssp = true;
+       }
 
        rc = cifs_enable_signing(server, ses->sign);
        if (rc)