CIFS: Enable encryption during session setup phase

BugLink: http://bugs.launchpad.net/bugs/1670508

In order to allow encryption on SMB connection we need to exchange
a session key and generate encryption and decryption keys.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
(cherry picked from commit cabfb368)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>

fs/cifs/sess.c

@@ -344,13 +344,12 @@ void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 	/* BB is NTLMV2 session security format easier to use here? */
 	flags = NTLMSSP_NEGOTIATE_56 |	NTLMSSP_REQUEST_TARGET |
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
-		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC;
-	if (ses->server->sign) {
+		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
+		NTLMSSP_NEGOTIATE_SEAL;
+	if (ses->server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-		if (!ses->server->session_estab ||
-				ses->ntlmssp->sesskey_per_smbsess)
-			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
-	}
+	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
 
@@ -407,13 +406,12 @@ int build_ntlmssp_auth_blob(unsigned char **pbuffer,
 	flags = NTLMSSP_NEGOTIATE_56 |
 		NTLMSSP_REQUEST_TARGET | NTLMSSP_NEGOTIATE_TARGET_INFO |
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
-		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC;
-	if (ses->server->sign) {
+		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
+		NTLMSSP_NEGOTIATE_SEAL;
+	if (ses->server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-		if (!ses->server->session_estab ||
-				ses->ntlmssp->sesskey_per_smbsess)
-			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
-	}
+	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	tmp = *pbuffer + sizeof(AUTHENTICATE_MESSAGE);
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);

fs/cifs/smb2pdu.c

@@ -752,15 +752,13 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 	struct cifs_ses *ses = sess_data->ses;
 
 	mutex_lock(&ses->server->srv_mutex);
-	if (ses->server->sign && ses->server->ops->generate_signingkey) {
+	if (ses->server->ops->generate_signingkey) {
 		rc = ses->server->ops->generate_signingkey(ses);
-		kfree(ses->auth_key.response);
-		ses->auth_key.response = NULL;
 		if (rc) {
 			cifs_dbg(FYI,
 				"SMB3 session key generation failed\n");
 			mutex_unlock(&ses->server->srv_mutex);
-			goto keygen_exit;
+			return rc;
 		}
 	}
 	if (!ses->server->session_estab) {
@@ -774,12 +772,6 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 	ses->status = CifsGood;
 	ses->need_reconnect = false;
 	spin_unlock(&GlobalMid_Lock);
-
-keygen_exit:
-	if (!ses->server->sign) {
-		kfree(ses->auth_key.response);
-		ses->auth_key.response = NULL;
-	}
 	return rc;
 }