fix(core): Disallow code generation in task runner (#12522)

docker/images/n8n/n8n-task-runners.json

@@ -4,7 +4,10 @@
 			"runner-type": "javascript",
 			"workdir": "/home/node",
 			"command": "/usr/local/bin/node",
-			"args": ["/usr/local/lib/node_modules/n8n/node_modules/@n8n/task-runner/dist/start.js"],
+			"args": [
+				"--disallow-code-generation-from-strings",
+				"/usr/local/lib/node_modules/n8n/node_modules/@n8n/task-runner/dist/start.js"
+			],
 			"allowed-env": [
 				"PATH",
 				"GENERIC_TIMEZONE",

packages/@n8n/task-runner/src/js-task-runner/__tests__/js-task-runner.test.ts

@@ -302,6 +302,7 @@ describe('JsTaskRunner', () => {
 				['typeof clearInterval', 'function'],
 				['typeof clearImmediate', 'function'],
 			],
+			eval: [['eval("1+2")', 3]],
 			'JS built-ins': [
 				['typeof btoa', 'function'],
 				['typeof atob', 'function'],

packages/@n8n/task-runner/src/js-task-runner/js-task-runner.ts

@@ -19,7 +19,7 @@ import type {
 } from 'n8n-workflow';
 import * as a from 'node:assert';
 import { inspect } from 'node:util';
-import { runInNewContext, type Context } from 'node:vm';
+import { type Context, createContext, runInContext } from 'node:vm';
 
 import type { MainConfig } from '@/config/main-config';
 import { UnsupportedFunctionError } from '@/js-task-runner/errors/unsupported-function.error';
@@ -158,10 +158,8 @@ export class JsTaskRunner extends TaskRunner {
 
 	private getNativeVariables() {
 		return {
-			// Exposed Node.js globals in vm2
+			// Exposed Node.js globals
 			Buffer,
-			Function,
-			eval,
 			setTimeout,
 			setInterval,
 			setImmediate,
@@ -205,7 +203,7 @@ export class JsTaskRunner extends TaskRunner {
 
 				signal.addEventListener('abort', abortHandler, { once: true });
 
-				const taskResult = runInNewContext(
+				const taskResult = runInContext(
 					`globalThis.global = globalThis; module.exports = async function VmCodeWrapper() {${settings.code}\n}()`,
 					context,
 					{ timeout: this.taskTimeout * 1000 },
@@ -268,7 +266,7 @@ export class JsTaskRunner extends TaskRunner {
 
 					signal.addEventListener('abort', abortHandler);
 
-					const taskResult = runInNewContext(
+					const taskResult = runInContext(
 						`module.exports = async function VmCodeWrapper() {${settings.code}\n}()`,
 						context,
 						{ timeout: this.taskTimeout * 1000 },
@@ -470,7 +468,7 @@ export class JsTaskRunner extends TaskRunner {
 		dataProxy: IWorkflowDataProxyData,
 		additionalProperties: Record<string, unknown> = {},
 	): Context {
-		const context: Context = {
+		return createContext({
 			[inspect.custom]: () => '[[ExecutionContext]]',
 			require: this.requireResolver,
 			module: {},
@@ -480,8 +478,6 @@ export class JsTaskRunner extends TaskRunner {
 			...dataProxy,
 			...this.buildRpcCallObject(taskId),
 			...additionalProperties,
-		};
+		});
-
-		return context;
 	}
 }

packages/cli/src/task-runners/__tests__/task-runner-process.test.ts

@@ -117,5 +117,16 @@ describe('TaskRunnerProcess', () => {
 			const options = spawnMock.mock.calls[0][2] as SpawnOptions;
 			expect(options.env).not.toHaveProperty('NODE_OPTIONS');
 		});
+
+		it('should use --disallow-code-generation-from-strings flag', async () => {
+			jest.spyOn(authService, 'createGrantToken').mockResolvedValue('grantToken');
+
+			await taskRunnerProcess.start();
+
+			expect(spawnMock.mock.calls[0].at(1)).toEqual([
+				'--disallow-code-generation-from-strings',
+				expect.stringContaining('/packages/@n8n/task-runner/dist/start.js'),
+			]);
+		});
 	});
 });

packages/cli/src/task-runners/task-runner-process.ts

@@ -106,7 +106,7 @@ export class TaskRunnerProcess extends TypedEmitter<TaskRunnerProcessEventMap> {
 	startNode(grantToken: string, taskBrokerUri: string) {
 		const startScript = require.resolve('@n8n/task-runner/start');
 
-		return spawn('node', [startScript], {
+		return spawn('node', ['--disallow-code-generation-from-strings', startScript], {
 			env: this.getProcessEnvVars(grantToken, taskBrokerUri),
 		});
 	}