fs/cifs: correctly to anonymous authentication for the NTLM(v1) authentication

commit 777f69b8 upstream.

Only server which map unknown users to guest will allow
access using a non-null NTChallengeResponse.

For Samba it's the "map to guest = bad user" option.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11913Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
[bwh: Backported to 3.16: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/cifs/sess.c

@@ -662,6 +662,7 @@ CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
 #endif
 	} else if (type == NTLM) {
 		pSMB->req_no_secext.Capabilities = cpu_to_le32(capabilities);
+		if (ses->user_name != NULL) {
 			pSMB->req_no_secext.CaseInsensitivePasswordLength =
 					cpu_to_le16(CIFS_AUTH_RESP_SIZE);
 			pSMB->req_no_secext.CaseSensitivePasswordLength =
@@ -682,6 +683,10 @@ CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
 			memcpy(bcc_ptr, ses->auth_key.response + CIFS_SESS_KEY_SIZE,
 					CIFS_AUTH_RESP_SIZE);
 			bcc_ptr += CIFS_AUTH_RESP_SIZE;
+		} else {
+			pSMB->req_no_secext.CaseInsensitivePasswordLength = 0;
+			pSMB->req_no_secext.CaseSensitivePasswordLength = 0;
+		}
 
 		if (ses->capabilities & CAP_UNICODE) {
 			/* unicode strings must be word aligned */