Also add endswith to lua parser (#443)

* Also add endswith to lua parser

Add endswith as a symbol so it can be parsed in filter expressions.

* Unit test for endswith support

Add a test case for endswith support, based on the filename ending with null.

test/falco_tests.yaml

@@ -264,6 +264,13 @@ trace_files: !mux
       - rules/rule_order.yaml
     trace_file: trace_files/cat_write.scap
 
+  endswith:
+    detect: True
+    detect_level: WARNING
+    rules_file:
+      - rules/endswith.yaml
+    trace_file: trace_files/cat_write.scap
+
   invalid_rule_output:
     exit_status: 1
     stderr_contains: "Runtime error: Error loading rules:.* Invalid output format 'An open was seen %not_a_real_field': 'invalid formatting token not_a_real_field'. Exiting."

test/rules/endswith.yaml

@@ -0,0 +1,22 @@
+#
+# Copyright (C) 2016-2018 Draios Inc dba Sysdig.
+#
+# This file is part of falco.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+- rule: open_ending with null
+  desc: A file ending with null is opened
+  condition: evt.type=open and fd.name endswith null
+  output: "An open was seen (command=%proc.cmdline)"
+  priority: WARNING

userspace/engine/lua/parser.lua

@@ -265,7 +265,8 @@ local G = {
           symb("contains") / "contains" +
           symb("icontains") / "icontains" +
           symb("glob") / "glob" +
-          symb("startswith") / "startswith";
+          symb("startswith") / "startswith" +
+          symb("endswith") / "endswith";
   InOp = kw("in") / "in";
   PmatchOp = kw("pmatch") / "pmatch";
   UnaryBoolOp = kw("not") / "not";