feat: default options for controlling proto access

This commmit adds the runtime options
- `allowProtoPropertiesByDefault` (boolean, default: false) and
- `allowProtoMethodsByDefault` (boolean, default: false)`
which can be used to allow access to prototype properties and
functions in general.

Specific properties and methods can still be disabled from access
via `allowedProtoProperties` and `allowedProtoMethods` by
setting the corresponding values to false.

The methods `constructor`, `__defineGetter__`, `__defineSetter__`, `__lookupGetter__`
and the property `__proto__` will be disabled, even if the allow...ByDefault-options
are set to true. In order to allow access to those properties and methods, they have
to be explicitly set to true in the 'allowedProto...'-options.

A warning is logged when the a proto-access it attempted and denied
by default (i.e. if no option is set by the user to make the access
decision explicit)

lib/handlebars/internal/proto-access.js

@@ -0,0 +1,55 @@
+import { createNewLookupObject } from './create-new-lookup-object';
+
+export function createProtoAccessControl(runtimeOptions) {
+  let defaultMethodWhiteList = Object.create(null);
+  defaultMethodWhiteList['constructor'] = false;
+  defaultMethodWhiteList['__defineGetter__'] = false;
+  defaultMethodWhiteList['__defineSetter__'] = false;
+  defaultMethodWhiteList['__lookupGetter__'] = false;
+
+  let defaultPropertyWhiteList = Object.create(null);
+  // eslint-disable-next-line no-proto
+  defaultPropertyWhiteList['__proto__'] = false;
+
+  return {
+    properties: {
+      whitelist: createNewLookupObject(
+        defaultPropertyWhiteList,
+        runtimeOptions.allowedProtoProperties
+      ),
+      defaultValue: runtimeOptions.allowProtoPropertiesByDefault
+    },
+    methods: {
+      whitelist: createNewLookupObject(
+        defaultMethodWhiteList,
+        runtimeOptions.allowedProtoMethods
+      ),
+      defaultValue: runtimeOptions.allowProtoMethodsByDefault
+    }
+  };
+}
+
+export function resultIsAllowed(result, protoAccessControl, propertyName) {
+  if (typeof result === 'function') {
+    return checkWhiteList(protoAccessControl.methods, propertyName);
+  } else {
+    return checkWhiteList(protoAccessControl.properties, propertyName);
+  }
+}
+
+function checkWhiteList(protoAccessControlForType, propertyName) {
+  if (protoAccessControlForType.whitelist[propertyName] !== undefined) {
+    return protoAccessControlForType.whitelist[propertyName] === true;
+  }
+  if (protoAccessControlForType.defaultValue !== undefined) {
+    return protoAccessControlForType.defaultValue;
+  }
+
+  // eslint-disable-next-line no-console
+  console.error(
+    `Handlebars: Access has been denied to resolve the property "${propertyName}" because it is not an "own property" of its parent.\n` +
+      `You can add a runtime option to disable the check or this warning:\n` +
+      `See http://localhost:8080/api-reference/runtime-options.html#options-to-control-prototype-access for details`
+  );
+  return false;
+}

lib/handlebars/runtime.js

@@ -8,7 +8,10 @@ import {
 } from './base';
 import { moveHelperToHooks } from './helpers';
 import { wrapHelper } from './internal/wrapHelper';
-import { createNewLookupObject } from './internal/createNewLookupObject';
+import {
+  createProtoAccessControl,
+  resultIsAllowed
+} from './internal/proto-access';
 
 export function checkRevision(compilerInfo) {
   const compilerRevision = (compilerInfo && compilerInfo[0]) || 1,
@@ -73,8 +76,7 @@ export function template(templateSpec, env) {
 
     let extendedOptions = Utils.extend({}, options, {
       hooks: this.hooks,
-      allowedProtoMethods: this.allowedProtoMethods,
+      protoAccessControl: this.protoAccessControl
-      allowedProtoProperties: this.allowedProtoProperties
     });
 
     let result = env.VM.invokePartial.call(
@@ -126,15 +128,14 @@ export function template(templateSpec, env) {
     },
     lookupProperty: function(parent, propertyName) {
       let result = parent[propertyName];
+      if (result == null) {
+        return result;
+      }
       if (Object.prototype.hasOwnProperty.call(parent, propertyName)) {
         return result;
       }
-      const whitelist =
-        typeof result === 'function'
-          ? container.allowedProtoMethods
-          : container.allowedProtoProperties;
 
-      if (whitelist[propertyName] === true) {
+      if (resultIsAllowed(result, container.protoAccessControl, propertyName)) {
         return result;
       }
       return undefined;
@@ -237,6 +238,7 @@ export function template(templateSpec, env) {
         )
       );
     }
+
     main = executeDecorators(
       templateSpec.main,
       main,
@@ -247,6 +249,7 @@ export function template(templateSpec, env) {
     );
     return main(context, options);
   }
+
   ret.isTop = true;
 
   ret._setup = function(options) {
@@ -271,12 +274,7 @@ export function template(templateSpec, env) {
       }
 
       container.hooks = {};
-      container.allowedProtoProperties = createNewLookupObject(
+      container.protoAccessControl = createProtoAccessControl(options);
-        options.allowedProtoProperties
-      );
-      container.allowedProtoMethods = createNewLookupObject(
-        options.allowedProtoMethods
-      );
 
       let keepHelperInHelpers =
         options.allowCallsToHelperMissing ||
@@ -284,8 +282,7 @@ export function template(templateSpec, env) {
       moveHelperToHooks(container, 'helperMissing', keepHelperInHelpers);
       moveHelperToHooks(container, 'blockHelperMissing', keepHelperInHelpers);
     } else {
-      container.allowedProtoProperties = options.allowedProtoProperties;
+      container.protoAccessControl = options.protoAccessControl; // internal option
-      container.allowedProtoMethods = options.allowedProtoMethods;
       container.helpers = options.helpers;
       container.partials = options.partials;
       container.decorators = options.decorators;

spec/security.js

@@ -149,176 +149,251 @@ describe('security issues', function() {
     });
   });
 
-  describe('GH-1595', function() {
+  describe('GH-1595: dangerous properties', function() {
-    it('properties, that are required to be own properties', function() {
+    var templates = [
-      expectTemplate('{{constructor}}')
+      '{{constructor}}',
-        .withInput({})
+      '{{__defineGetter__}}',
-        .toCompileTo('');
+      '{{__defineSetter__}}',
+      '{{__lookupGetter__}}',
+      '{{__proto__}}',
+      '{{lookup this "constructor"}}',
+      '{{lookup this "__defineGetter__"}}',
+      '{{lookup this "__defineSetter__"}}',
+      '{{lookup this "__lookupGetter__"}}',
+      '{{lookup this "__proto__"}}'
+    ];
 
-      expectTemplate('{{__defineGetter__}}')
+    templates.forEach(function(template) {
-        .withInput({})
+      describe('access should be denied to ' + template, function() {
-        .toCompileTo('');
+        it('by default', function() {
+          expectTemplate(template)
+            .withInput({})
+            .toCompileTo('');
+        });
+        it(' with proto-access enabled', function() {
+          expectTemplate(template)
+            .withInput({})
+            .withRuntimeOptions({
+              allowProtoPropertiesByDefault: true,
+              allowProtoMethodsByDefault: true
+            })
+            .toCompileTo('');
+        });
+      });
+    });
+  });
+  describe('GH-1631: disallow access to prototype functions', function() {
+    function TestClass() {}
 
-      expectTemplate('{{__defineSetter__}}')
+    TestClass.prototype.aProperty = 'propertyValue';
-        .withInput({})
+    TestClass.prototype.aMethod = function() {
-        .toCompileTo('');
+      return 'returnValue';
+    };
 
-      expectTemplate('{{__lookupGetter__}}')
+    afterEach(function() {
-        .withInput({})
+      sinon.restore();
-        .toCompileTo('');
-
-      expectTemplate('{{__proto__}}')
-        .withInput({})
-        .toCompileTo('');
-
-      expectTemplate('{{lookup this "constructor"}}')
-        .withInput({})
-        .toCompileTo('');
-
-      expectTemplate('{{lookup this "__defineGetter__"}}')
-        .withInput({})
-        .toCompileTo('');
-
-      expectTemplate('{{lookup this "__defineSetter__"}}')
-        .withInput({})
-        .toCompileTo('');
-
-      expectTemplate('{{lookup this "__lookupGetter__"}}')
-        .withInput({})
-        .toCompileTo('');
-
-      expectTemplate('{{lookup this "__proto__"}}')
-        .withInput({})
-        .toCompileTo('');
     });
 
-    describe('GH-1631: disallow access to prototype functions', function() {
+    describe('control access to prototype methods via "allowedProtoMethods"', function() {
-      function TestClass() {}
+      checkProtoMethodAccess({});
 
-      TestClass.prototype.aProperty = 'propertyValue';
+      describe('in compat mode', function() {
-      TestClass.prototype.aMethod = function() {
+        checkProtoMethodAccess({ compat: true });
-        return 'returnValue';
+      });
-      };
+
+      function checkProtoMethodAccess(compileOptions) {
+        it('should be prohibited by default and log a warning', function() {
+          var spy = sinon.spy(console, 'error');
 
-      describe('control access to prototype methods via "allowedProtoMethods"', function() {
-        it('should be prohibited by default', function() {
           expectTemplate('{{aMethod}}')
             .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
             .toCompileTo('');
+
+          expect(spy.calledOnce).to.be.true();
+          expect(spy.args[0][0]).to.match(/Handlebars: Access has been denied/);
         });
 
-        it('can be allowed', function() {
+        it('can be allowed, which disables the warning', function() {
+          var spy = sinon.spy(console, 'error');
+
           expectTemplate('{{aMethod}}')
             .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
             .withRuntimeOptions({
               allowedProtoMethods: {
                 aMethod: true
               }
             })
             .toCompileTo('returnValue');
+
+          expect(spy.callCount).to.equal(0);
         });
 
-        it('should be prohibited by default (in "compat" mode)', function() {
+        it('can be turned on by default, which disables the warning', function() {
-          expectTemplate('{{aMethod}}')
+          var spy = sinon.spy(console, 'error');
-            .withInput(new TestClass())
-            .withCompileOptions({ compat: true })
-            .toCompileTo('');
-        });
 
-        it('can be allowed (in "compat" mode)', function() {
           expectTemplate('{{aMethod}}')
             .withInput(new TestClass())
-            .withCompileOptions({ compat: true })
+            .withCompileOptions(compileOptions)
             .withRuntimeOptions({
-              allowedProtoMethods: {
+              allowProtoMethodsByDefault: true
-                aMethod: true
-              }
             })
             .toCompileTo('returnValue');
+
+          expect(spy.callCount).to.equal(0);
         });
 
-        it('should cause the recursive lookup by default (in "compat" mode)', function() {
+        it('can be turned off by default, which disables the warning', function() {
-          expectTemplate('{{#aString}}{{trim}}{{/aString}}')
+          var spy = sinon.spy(console, 'error');
-            .withInput({ aString: '  abc  ', trim: 'trim' })
-            .withCompileOptions({ compat: true })
-            .toCompileTo('trim');
-        });
 
-        it('should not cause the recursive lookup if allowed through options(in "compat" mode)', function() {
+          expectTemplate('{{aMethod}}')
-          expectTemplate('{{#aString}}{{trim}}{{/aString}}')
+            .withInput(new TestClass())
-            .withInput({ aString: '  abc  ', trim: 'trim' })
+            .withCompileOptions(compileOptions)
-            .withCompileOptions({ compat: true })
             .withRuntimeOptions({
+              allowProtoMethodsByDefault: false
+            })
+            .toCompileTo('');
+
+          expect(spy.callCount).to.equal(0);
+        });
+
+        it('can be turned off, if turned on by default', function() {
+          expectTemplate('{{aMethod}}')
+            .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
+            .withRuntimeOptions({
+              allowProtoMethodsByDefault: true,
               allowedProtoMethods: {
-                trim: true
+                aMethod: false
               }
             })
-            .toCompileTo('abc');
-        });
-      });
-
-      describe('control access to prototype non-methods via "allowedProtoProperties"', function() {
-        it('should be prohibited by default', function() {
-          expectTemplate('{{aProperty}}')
-            .withInput(new TestClass())
             .toCompileTo('');
         });
+      }
+
+      it('should cause the recursive lookup by default (in "compat" mode)', function() {
+        expectTemplate('{{#aString}}{{trim}}{{/aString}}')
+          .withInput({ aString: '  abc  ', trim: 'trim' })
+          .withCompileOptions({ compat: true })
+          .toCompileTo('trim');
+      });
+
+      it('should not cause the recursive lookup if allowed through options(in "compat" mode)', function() {
+        expectTemplate('{{#aString}}{{trim}}{{/aString}}')
+          .withInput({ aString: '  abc  ', trim: 'trim' })
+          .withCompileOptions({ compat: true })
+          .withRuntimeOptions({
+            allowedProtoMethods: {
+              trim: true
+            }
+          })
+          .toCompileTo('abc');
+      });
+    });
+
+    describe('control access to prototype non-methods via "allowedProtoProperties" and "allowProtoPropertiesByDefault', function() {
+      checkProtoPropertyAccess({});
+
+      describe('in compat-mode', function() {
+        checkProtoPropertyAccess({ compat: true });
+      });
+
+      function checkProtoPropertyAccess(compileOptions) {
+        it('should be prohibited by default and log a warning', function() {
+          var spy = sinon.spy(console, 'error');
 
-        it('can be turned on', function() {
           expectTemplate('{{aProperty}}')
             .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
+            .toCompileTo('');
+
+          expect(spy.calledOnce).to.be.true();
+          expect(spy.args[0][0]).to.match(/Handlebars: Access has been denied/);
+        });
+
+        it('can be explicitly prohibited by default, which disables the warning', function() {
+          var spy = sinon.spy(console, 'error');
+
+          expectTemplate('{{aProperty}}')
+            .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
+            .withRuntimeOptions({
+              allowProtoPropertiesByDefault: false
+            })
+            .toCompileTo('');
+
+          expect(spy.callCount).to.equal(0);
+        });
+
+        it('can be turned on, which disables the warning', function() {
+          var spy = sinon.spy(console, 'error');
+
+          expectTemplate('{{aProperty}}')
+            .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
             .withRuntimeOptions({
               allowedProtoProperties: {
                 aProperty: true
               }
             })
             .toCompileTo('propertyValue');
+
+          expect(spy.callCount).to.equal(0);
         });
 
-        it('should be prohibited by default (in "compat" mode)', function() {
+        it('can be turned on by default, which disables the warning', function() {
-          expectTemplate('{{aProperty}}')
+          var spy = sinon.spy(console, 'error');
-            .withInput(new TestClass())
-            .withCompileOptions({ compat: true })
-            .toCompileTo('');
-        });
 
-        it('can be turned on (in "compat" mode)', function() {
           expectTemplate('{{aProperty}}')
             .withInput(new TestClass())
-            .withCompileOptions({ compat: true })
+            .withCompileOptions(compileOptions)
             .withRuntimeOptions({
-              allowedProtoProperties: {
+              allowProtoPropertiesByDefault: true
-                aProperty: true
-              }
             })
             .toCompileTo('propertyValue');
+
+          expect(spy.callCount).to.equal(0);
+        });
+
+        it('can be turned off, if turned on by default', function() {
+          expectTemplate('{{aProperty}}')
+            .withInput(new TestClass())
+            .withCompileOptions(compileOptions)
+            .withRuntimeOptions({
+              allowProtoPropertiesByDefault: true,
+              allowedProtoProperties: {
+                aProperty: false
+              }
+            })
+            .toCompileTo('');
+        });
+      }
+    });
+
+    describe('compatibility with old runtimes, that do not provide the function "container.lookupProperty"', function() {
+      beforeEach(function simulateRuntimeWithoutLookupProperty() {
+        var oldTemplateMethod = handlebarsEnv.template;
+        sinon.replace(handlebarsEnv, 'template', function(templateSpec) {
+          templateSpec.main = wrapToAdjustContainer(templateSpec.main);
+          return oldTemplateMethod.call(this, templateSpec);
         });
       });
 
-      describe('compatibility with old runtimes, that do not provide the function "container.lookupProperty"', function() {
+      afterEach(function() {
-        beforeEach(function simulateRuntimeWithoutLookupProperty() {
+        sinon.restore();
-          var oldTemplateMethod = handlebarsEnv.template;
+      });
-          sinon.replace(handlebarsEnv, 'template', function(templateSpec) {
-            templateSpec.main = wrapToAdjustContainer(templateSpec.main);
-            return oldTemplateMethod.call(this, templateSpec);
-          });
-        });
 
-        afterEach(function() {
+      it('should work with simple properties', function() {
-          sinon.restore();
+        expectTemplate('{{aProperty}}')
-        });
+          .withInput({ aProperty: 'propertyValue' })
+          .toCompileTo('propertyValue');
+      });
 
-        it('should work with simple properties', function() {
+      it('should work with Array.prototype.length', function() {
-          expectTemplate('{{aProperty}}')
+        expectTemplate('{{anArray.length}}')
-            .withInput({ aProperty: 'propertyValue' })
+          .withInput({ anArray: ['a', 'b', 'c'] })
-            .toCompileTo('propertyValue');
+          .toCompileTo('3');
-        });
-
-        it('should work with Array.prototype.length', function() {
-          expectTemplate('{{anArray.length}}')
-            .withInput({ anArray: ['a', 'b', 'c'] })
-            .toCompileTo('3');
-        });
       });
     });
   });

types/index.d.ts

@@ -30,8 +30,10 @@ declare namespace Handlebars {
       data?: any;
       blockParams?: any[];
       allowCallsToHelperMissing?: boolean;
-      allowedProtoProperties?: { [name: string]: boolean }
+      allowedProtoProperties?: { [name: string]: boolean };
-      allowedProtoMethods?: { [name: string]: boolean }
+      allowedProtoMethods?: { [name: string]: boolean };
+      allowProtoPropertiesByDefault?: boolean;
+      allowProtoMethodsByDefault?: boolean;
   }
 
   export interface HelperOptions {

types/test.ts

@@ -241,12 +241,14 @@ function testExceptionWithNodeTypings() {
   let stack: string | undefined = exception.stack;
 }
 
-function testProtoPropertyControlOptions() {
+function testProtoAccessControlControlOptions() {
   Handlebars.compile('test')(
     {},
     {
       allowedProtoMethods: { allowedMethod: true, forbiddenMethod: false },
-      allowedProtoProperties: { allowedProperty: true, forbiddenProperty: false }
+      allowedProtoProperties: { allowedProperty: true, forbiddenProperty: false },
+      allowProtoMethodsByDefault: true,
+      allowProtoPropertiesByDefault: false,
     }
   );
 }