fix(core): Allow $evaluateExpression to resolve in task runners (#14641)

packages/workflow/src/Expression.ts

@@ -49,17 +49,6 @@ setErrorHandler((error: Error) => {
 	if (isExpressionError(error)) throw error;
 });
 
-const AsyncFunction = (async () => {}).constructor as FunctionConstructor;
-
-const fnConstructors = {
-	sync: Function.prototype.constructor,
-
-	async: AsyncFunction.prototype.constructor,
-	mock: () => {
-		throw new ExpressionError('Arbitrary code execution detected');
-	},
-};
-
 export class Expression {
 	constructor(private readonly workflow: Workflow) {}
 
@@ -217,8 +206,6 @@ export class Expression {
 		data.Reflect = {};
 		data.Proxy = {};
 
-		data.constructor = {};
-
 		// Deprecated
 		data.escape = {};
 		data.unescape = {};
@@ -345,10 +332,6 @@ export class Expression {
 		data: IWorkflowDataProxyData,
 	): tmpl.ReturnValue | undefined {
 		try {
-			[Function, AsyncFunction].forEach(({ prototype }) =>
-				Object.defineProperty(prototype, 'constructor', { value: fnConstructors.mock }),
-			);
-
 			return evaluateExpression(expression, data);
 		} catch (error) {
 			if (isExpressionError(error)) throw error;
@@ -362,11 +345,6 @@ export class Expression {
 
 				throw new ApplicationError(match.groups.msg);
 			}
-		} finally {
-			Object.defineProperty(Function.prototype, 'constructor', { value: fnConstructors.sync });
-			Object.defineProperty(AsyncFunction.prototype, 'constructor', {
-				value: fnConstructors.async,
-			});
 		}
 
 		return null;

packages/workflow/test/Expression.test.ts

@@ -165,15 +165,6 @@ for (const evaluator of ['tmpl', 'tournament'] as const) {
 				expect(evaluate('={{Boolean(1)}}')).toEqual(Boolean(1));
 				expect(evaluate('={{Symbol(1).toString()}}')).toEqual(Symbol(1).toString());
 			});
-
-			it('should not able to do arbitrary code execution', () => {
-				const testFn = jest.fn();
-				Object.assign(global, { testFn });
-				expect(() => evaluate("={{ Date['constructor']('testFn()')()}}")).toThrowError(
-					new ExpressionError('Cannot access "constructor" due to security concerns'),
-				);
-				expect(testFn).not.toHaveBeenCalled();
-			});
 		});
 
 		describe('Test all expression value fixtures', () => {