MXS-2393 Add parameter 'require_fully_parsed'

If set to true and if any of the other blocking related parameters
is true, then a statement that cannot be fully parsed will be blocked.

Default is true.

Documentation/Filters/Masking.md

@@ -87,6 +87,15 @@ SELECT revealed_ssn FROM cheat;
 ```
 to get access to the cleartext version of a masked field `ssn`.
 
+From MaxScale 2.3.5 onwards, the masking filter will, if any of the
+`prevent_function_usage`, `check_user_variables`, `check_unions` or
+`check_subqueries` parameters is set to true, block statements that
+cannot be fully parsed.
+
+Please see the configuration parameter
+[require_fully_parsed](#require_fully_parsed)
+for how to change the default behaviour.
+
 ## Limitations
 
 The masking filter can _only_ be used for masking columns of the following
@@ -186,6 +195,26 @@ prevent_function_usage=false
 ```
 The default value is `true`.
 
+#### `require_fully_parsed`
+
+This optional parameter specifies how the masking filter should
+behave in case any of `prevent_function_usage`, `check_user_variables`,
+`check_unions` or `check_subqueries` is true and it encounters a
+statement that cannot be fully parsed,
+
+If true, then statements that cannot be fully parsed (due to a
+parser limitation) will be blocked.
+```
+require_fully_parsed=false
+```
+
+The default value is `true`.
+
+Note that if this parameter is set to false, then `prevent_function_usage`,
+`check_user_variables`, `check_unions` and `check_subqueries` are rendered
+less effective, as it with a statement that can not be fully parsed may be
+possible to bypass the protection that they are intended to provide.
+
 #### `check_user_variables`
 
 This optional parameter specifies how the masking filter should

server/modules/filter/masking/maskingfilter.cc

@@ -139,6 +139,12 @@ extern "C" MXS_MODULE* MXS_CREATE_MODULE()
                 Config::check_subqueries_default,
                 MXS_MODULE_OPT_NONE,
             },
+            {
+                Config::require_fully_parsed_name,
+                MXS_MODULE_PARAM_BOOL,
+                Config::require_fully_parsed_default,
+                MXS_MODULE_OPT_NONE,
+            },
             {MXS_END_MODULE_PARAMS}
         }
     };

server/modules/filter/masking/maskingfilterconfig.cc

@@ -17,21 +17,23 @@
 namespace
 {
 
-const char config_name_large_payload[] = "large_payload";
+const char config_name_check_subqueries[]       = "check_subqueries";
-const char config_name_rules[] = "rules";
+const char config_name_check_unions[]           = "check_unions";
-const char config_name_warn_type_mismatch[] = "warn_type_mismatch";
+const char config_name_check_user_variables[]   = "check_user_variables";
-
+const char config_name_large_payload[]          = "large_payload";
-const char config_value_abort[] = "abort";
-const char config_value_ignore[] = "ignore";
-const char config_value_never[] = "never";
-const char config_value_always[] = "always";
-
 const char config_name_prevent_function_usage[] = "prevent_function_usage";
-const char config_check_user_variables[] = "check_user_variables";
+const char config_name_require_fully_parsed[]   = "require_fully_parsed";
-const char config_check_unions[] = "check_unions";
+const char config_name_rules[]                  = "rules";
-const char config_check_subqueries[] = "check_subqueries";
+const char config_name_warn_type_mismatch[]     = "warn_type_mismatch";
+
+
+const char config_value_abort[]  = "abort";
+const char config_value_always[] = "always";
+const char config_value_ignore[] = "ignore";
+const char config_value_never[]  = "never";
 
 const char config_value_true[] = "true";
+
 }
 
 /*
@@ -63,10 +65,9 @@ const char* MaskingFilterConfig::rules_name = config_name_rules;
  * PARAM warn_type_mismatch
  */
 
-// static
 const char* MaskingFilterConfig::warn_type_mismatch_name = config_name_warn_type_mismatch;
+const char* MaskingFilterConfig::warn_type_mismatch_default = config_value_never;
 
-// static
 const MXS_ENUM_VALUE MaskingFilterConfig::warn_type_mismatch_values[] =
 {
     {config_value_never,  MaskingFilterConfig::WARN_NEVER   },
@@ -74,46 +75,36 @@ const MXS_ENUM_VALUE MaskingFilterConfig::warn_type_mismatch_values[] =
     {NULL}
 };
 
-// static
-const char* MaskingFilterConfig::warn_type_mismatch_default = config_value_never;
-
 /*
  * PARAM prevent_function_usage
  */
-
-// static
 const char* MaskingFilterConfig::prevent_function_usage_name = config_name_prevent_function_usage;
-
-// static
 const char* MaskingFilterConfig::prevent_function_usage_default = config_value_true;
 
 /*
  * PARAM check_user_variables
  */
-// static
+const char* MaskingFilterConfig::check_user_variables_name = config_name_check_user_variables;
-const char* MaskingFilterConfig::check_user_variables_name = config_check_user_variables;
-
-// static
 const char* MaskingFilterConfig::check_user_variables_default = config_value_true;
 
 /*
  * PARAM check_unions
  */
-// static
+const char* MaskingFilterConfig::check_unions_name = config_name_check_unions;
-const char* MaskingFilterConfig::check_unions_name = config_check_unions;
-
-// static
 const char* MaskingFilterConfig::check_unions_default = config_value_true;
 
 /*
  * PARAM check_subqueries
  */
-// static
+const char* MaskingFilterConfig::check_subqueries_name = config_name_check_subqueries;
-const char* MaskingFilterConfig::check_subqueries_name = config_check_subqueries;
-
-// static
 const char* MaskingFilterConfig::check_subqueries_default = config_value_true;
 
+/*
+ * PARAM require_fully_parsed
+ */
+const char* MaskingFilterConfig::require_fully_parsed_name = config_name_require_fully_parsed;
+const char* MaskingFilterConfig::require_fully_parsed_default = config_name_require_fully_parsed;
+
 
 /*
  * MaskingFilterConfig
@@ -164,3 +155,9 @@ bool MaskingFilterConfig::get_check_subqueries(const MXS_CONFIG_PARAMETER* pPara
 {
     return config_get_bool(pParams, check_subqueries_name);
 }
+
+// static
+bool MaskingFilterConfig::get_require_fully_parsed(const MXS_CONFIG_PARAMETER* pParams)
+{
+    return config_get_bool(pParams, require_fully_parsed_name);
+}

server/modules/filter/masking/maskingfilterconfig.hh

@@ -54,6 +54,9 @@ public:
     static const char* check_subqueries_name;
     static const char* check_subqueries_default;
 
+    static const char* require_fully_parsed_name;
+    static const char* require_fully_parsed_default;
+
     MaskingFilterConfig(const char* zName, const MXS_CONFIG_PARAMETER* pParams)
         : m_name(zName)
         , m_large_payload(get_large_payload(pParams))
@@ -63,6 +66,7 @@ public:
         , m_check_user_variables(get_check_user_variables(pParams))
         , m_check_unions(get_check_unions(pParams))
         , m_check_subqueries(get_check_subqueries(pParams))
+        , m_require_fully_parsed(get_require_fully_parsed(pParams))
     {
     }
 
@@ -110,6 +114,11 @@ public:
         return m_check_subqueries;
     }
 
+    bool require_fully_parsed() const
+    {
+        return m_require_fully_parsed;
+    }
+
     void set_large_payload(large_payload_t l)
     {
         m_large_payload = l;
@@ -144,6 +153,11 @@ public:
         m_check_subqueries = b;
     }
 
+    void set_require_fully_parsed(bool b)
+    {
+        m_require_fully_parsed = b;
+    }
+
     bool is_parsing_needed() const
     {
         return prevent_function_usage() || check_user_variables() || check_unions() || check_subqueries();
@@ -156,6 +170,7 @@ public:
     static bool                 get_check_user_variables(const MXS_CONFIG_PARAMETER* pParams);
     static bool                 get_check_unions(const MXS_CONFIG_PARAMETER* pParams);
     static bool                 get_check_subqueries(const MXS_CONFIG_PARAMETER* pParams);
+    static bool                 get_require_fully_parsed(const MXS_CONFIG_PARAMETER* pParams);
 
 private:
     std::string          m_name;
@@ -166,4 +181,5 @@ private:
     bool                 m_check_user_variables;
     bool                 m_check_unions;
     bool                 m_check_subqueries;
+    bool                 m_require_fully_parsed;
 };

server/modules/filter/masking/maskingfiltersession.cc

@@ -127,7 +127,8 @@ bool MaskingFilterSession::check_textual_query(GWBUF* pPacket)
 {
     bool rv = false;
 
-    if (qc_parse(pPacket, QC_COLLECT_FIELDS | QC_COLLECT_FUNCTIONS) == QC_QUERY_PARSED)
+    if (qc_parse(pPacket, QC_COLLECT_FIELDS | QC_COLLECT_FUNCTIONS) == QC_QUERY_PARSED
+        || !m_filter.config().require_fully_parsed())
     {
         if (qc_query_is_type(qc_get_type_mask(pPacket), QUERY_TYPE_PREPARE_NAMED_STMT))
         {
@@ -165,7 +166,8 @@ bool MaskingFilterSession::check_binary_query(GWBUF* pPacket)
 {
     bool rv = false;
 
-    if (qc_parse(pPacket, QC_COLLECT_FIELDS | QC_COLLECT_FUNCTIONS) == QC_QUERY_PARSED)
+    if (qc_parse(pPacket, QC_COLLECT_FIELDS | QC_COLLECT_FUNCTIONS) == QC_QUERY_PARSED
+        || !m_filter.config().require_fully_parsed())
     {
         rv = check_query(pPacket);
     }