iscsi-target: Always send a response before terminating iSCSI connection

There are some cases, for example when the initiator sends an
out-of-bounds ErrorRecoveryLevel value, where the iSCSI target
terminates the connection without sending back any error.  Audit the
login path and add appropriate iscsit_tx_login_rsp() calls to make
sure this doesn't happen.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_login.c

@@ -127,13 +127,13 @@ int iscsi_check_for_session_reinstatement(struct iscsi_conn *conn)
 
 	initiatorname_param = iscsi_find_param_from_key(
 			INITIATORNAME, conn->param_list);
-	if (!initiatorname_param)
-		return -1;
-
 	sessiontype_param = iscsi_find_param_from_key(
 			SESSIONTYPE, conn->param_list);
-	if (!sessiontype_param)
+	if (!initiatorname_param || !sessiontype_param) {
+		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
+			ISCSI_LOGIN_STATUS_MISSING_FIELDS);
 		return -1;
+	}
 
 	sessiontype = (strncmp(sessiontype_param->value, NORMAL, 6)) ? 1 : 0;
 

drivers/target/iscsi/iscsi_target_nego.c

@@ -620,8 +620,11 @@ static int iscsi_target_handle_csg_one(struct iscsi_conn *conn, struct iscsi_log
 			login->req_buf,
 			payload_length,
 			conn);
-	if (ret < 0)
+	if (ret < 0) {
+		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
+				ISCSI_LOGIN_STATUS_INIT_ERR);
 		return -1;
+	}
 
 	if (login->first_request)
 		if (iscsi_target_check_first_request(conn, login) < 0)
@@ -636,8 +639,11 @@ static int iscsi_target_handle_csg_one(struct iscsi_conn *conn, struct iscsi_log
 			login->rsp_buf,
 			&login->rsp_length,
 			conn->param_list);
-	if (ret < 0)
+	if (ret < 0) {
+		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
+				ISCSI_LOGIN_STATUS_INIT_ERR);
 		return -1;
+	}
 
 	if (!login->auth_complete &&
 	     ISCSI_TPG_ATTRIB(ISCSI_TPG_C(conn))->authentication) {