cifs: Fix signing failure when server mandates signing for NTLMSSP

When using NTLMSSP authentication mechanism, if server mandates
signing, keep the flags in type 3 messages of the NTLMSSP exchange
same as in type 1 messages (i.e. keep the indicated capabilities same).

Some of the servers such as Samba, expect the flags such as
Negotiate_Key_Exchange in type 3 message of NTLMSSP exchange as well.
Some servers like Windows do not.

https://bugzilla.samba.org/show_bug.cgi?id=8212

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/sess.c

@@ -428,8 +428,7 @@ static void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 			(SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
 		if (!ses->server->session_estab)
-			flags |= NTLMSSP_NEGOTIATE_KEY_XCH |
-				NTLMSSP_NEGOTIATE_EXTENDED_SEC;
+			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 	}
 
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
@@ -465,10 +464,11 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer,
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
 		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC;
 	if (ses->server->sec_mode &
-	   (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
+	   (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-	if (ses->server->sec_mode & SECMODE_SIGN_REQUIRED)
-		flags |= NTLMSSP_NEGOTIATE_ALWAYS_SIGN;
+		if (!ses->server->session_estab)
+			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
+	}
 
 	tmp = pbuffer + sizeof(AUTHENTICATE_MESSAGE);
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);