#136: Fixed switching the source schema (#143)

* #136: Fixed source schema switching.

Co-authored-by: Christoph Pirkl <[email protected]>

doc/changes/changes_1.5.1.md

@@ -1,13 +1,16 @@
-# Exasol Row Level Security (Lua) 1.5.1, released 2023-10-25
+# Exasol Row Level Security (Lua) 1.5.1, released 2023-10-26
 
-Code name: Fix CVE-2023-42503
+Code name: Fix CVE-2023-42503 and source schema switching
 
 ## Summary
 
 In this release we updated the test dependency `exasol-testcontainers` to version 6.6.2 in order to update the transitive dependency `org.apache.commons:commons-compress` to 1.24.0. This fixes CVE-2023-42505.
 
+We also fixed a bug that prevented users from switching the source schema with `ALTER VIRTUAL SCHEMA ... SET SCHEMA_NAME=`.
+
 ## Features
 
+* #136: Fixed source schema switching
 * #140: Updated test dependency to fix CVE-2023-42505
 
 ## Dependency Updates

src/main/lua/exasol/rls/RlsAdapter.lua

@@ -1,3 +1,5 @@
+local log = require("remotelog")
+
 -- Derive from AbstractVirtualSchemaAdapter
 local RlsAdapter = {}
 RlsAdapter.__index = RlsAdapter
@@ -63,12 +65,19 @@ function RlsAdapter:refresh(request, properties)
 end
 
 --- Alter the schema properties.
+-- This request provides two sets of user-defined properties. The old ones (i.e. the ones that where set before this
+-- request) and the properties that the user changed.
 -- @param request virtual schema request
--- @param properties user-defined properties
+-- @param old_properties old user-defined properties
+-- @param new_properties new user-defined properties
 -- @return response containing the metadata for the virtual schema like table and column structure
-function RlsAdapter:set_properties(request, properties)
-    properties:validate()
-    return {type = "setProperties", schemaMetadata = self:_handle_schema_scanning_request(request, properties)}
+function RlsAdapter:set_properties(request, old_properties, new_properties)
+    log.debug("Old properties " .. tostring(old_properties))
+    log.debug("New properties " .. tostring(new_properties))
+    local merged_properties = old_properties:merge(new_properties)
+    log.debug("Merged properties " .. tostring(merged_properties))
+    merged_properties:validate()
+    return {type = "setProperties", schemaMetadata = self:_handle_schema_scanning_request(request, merged_properties)}
 end
 
 --- Rewrite a pushed down query.

src/test/java/com/exasol/AbstractLuaVirtualSchemaIT.java

@@ -46,6 +46,7 @@ abstract class AbstractLuaVirtualSchemaIT {
             + "        end\n" //
             + "    end\n" //
             + ")\n\n";
+    public static final String DEFAULT_LOG_PORT = "3000";
     protected static Connection connection;
     protected static ExasolObjectFactory factory;
     private static ExasolSchema scriptSchema;
@@ -85,7 +86,17 @@ protected VirtualSchema createVirtualSchema(final Schema sourceSchema, final Map
     }
 
     protected VirtualSchema createVirtualSchema(final Schema sourceSchema) {
-        return createVirtualSchema(sourceSchema, Collections.emptyMap());
+        return createVirtualSchema(sourceSchema, getDebugProperties());
+    }
+
+    private Map<String, String> getDebugProperties() {
+        final String debugHost = System.getProperty("com.exasol.log.host");
+        if(debugHost == null) {
+            return Collections.emptyMap();
+        } else {
+            final String debugAddress = debugHost + ":" + System.getProperty("com.exasol.log.port", DEFAULT_LOG_PORT);
+            return Map.of("DEBUG_ADDRESS", debugAddress, "LOG_LEVEL", "TRACE");
+        }
     }
 
     protected AdapterScript createAdapterScript(final String prefix) throws IOException {

src/test/java/com/exasol/MetadataReadingIT.java

@@ -196,6 +196,30 @@ private void execute(final String sql) throws SQLException {
         }
     }
 
+    @Test
+    void testChangeSourceSchema() {
+        final Schema sourceSchemaBefore = createSchema("SCHEMA_SWITCH");
+        final Table tableBefore = sourceSchemaBefore.createTable("T_BEFORE", "I", "DECIMAL(18,0)");
+        final Schema sourceSchemaAfter = createSchema("SCHEMA_AFTER_SWITCH");
+        final Table tableAfter = sourceSchemaAfter.createTable("T_AFTER", "D", "DATE");
+        final VirtualSchema virtualSchema = createVirtualSchema(sourceSchemaBefore);
+        final User user = createUserWithVirtualSchemaAccess("USER_FOR_SCHEMA_SWITCH", virtualSchema);
+        assertVirtualTableStructure(tableBefore, user, expectRows("I", "DECIMAL(18,0)"));
+        replaceSourceSchema(virtualSchema, sourceSchemaAfter);
+        assertRlsQueryWithUser("/*snapshot execution*/DESCRIBE SCHEMA_SWITCH_RLS.T_AFTER", user,
+                expectRows("D", "DATE"));
+    }
+
+    private void replaceSourceSchema(final VirtualSchema virtualSchema, final Schema sourceSchema) {
+        final String sql = "ALTER VIRTUAL SCHEMA " + virtualSchema.getFullyQualifiedName() + " SET SCHEMA_NAME='" +
+                sourceSchema.getName() + "'";
+        try {
+            execute(sql);
+        } catch (final SQLException exception) {
+            throw new AssertionError("Unable to replace source schema using query '" + sql + "'", exception);
+        }
+    }
+
     @Test
     void testProtectTableAfterRefresh() throws SQLException {
         final Schema sourceSchema = createSchema("SCHEMA_FOR_PROTECT_AFTER_REFRESH");