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Diffstat (limited to 'js/xpconnect/wrappers/XrayWrapper.cpp')
| -rw-r--r-- | js/xpconnect/wrappers/XrayWrapper.cpp | 2351 |
1 files changed, 2351 insertions, 0 deletions
diff --git a/js/xpconnect/wrappers/XrayWrapper.cpp b/js/xpconnect/wrappers/XrayWrapper.cpp new file mode 100644 index 0000000000..cdedb02a5f --- /dev/null +++ b/js/xpconnect/wrappers/XrayWrapper.cpp @@ -0,0 +1,2351 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "XrayWrapper.h" +#include "AccessCheck.h" +#include "WrapperFactory.h" + +#include "nsDependentString.h" +#include "nsIConsoleService.h" +#include "nsIScriptError.h" + +#include "xpcprivate.h" + +#include "jsapi.h" +#include "js/CallAndConstruct.h" // JS::Call, JS::Construct, JS::IsCallable +#include "js/ColumnNumber.h" // JS::ColumnNumberOneOrigin +#include "js/experimental/TypedData.h" // JS_GetTypedArrayLength +#include "js/friend/WindowProxy.h" // js::IsWindowProxy +#include "js/friend/XrayJitInfo.h" // JS::XrayJitInfo +#include "js/Object.h" // JS::GetClass, JS::GetCompartment, JS::GetReservedSlot, JS::SetReservedSlot +#include "js/PropertyAndElement.h" // JS_AlreadyHasOwnPropertyById, JS_DefineProperty, JS_DefinePropertyById, JS_DeleteProperty, JS_DeletePropertyById, JS_HasProperty, JS_HasPropertyById +#include "js/PropertyDescriptor.h" // JS::PropertyDescriptor, JS_GetOwnPropertyDescriptorById, JS_GetPropertyDescriptorById +#include "js/PropertySpec.h" +#include "nsGlobalWindowInner.h" +#include "nsJSUtils.h" +#include "nsPrintfCString.h" + +#include "mozilla/FloatingPoint.h" +#include "mozilla/dom/BindingUtils.h" +#include "mozilla/dom/ProxyHandlerUtils.h" +#include "mozilla/dom/WindowProxyHolder.h" +#include "mozilla/dom/XrayExpandoClass.h" + +using namespace mozilla::dom; +using namespace JS; +using namespace mozilla; + +using js::BaseProxyHandler; +using js::CheckedUnwrapStatic; +using js::IsCrossCompartmentWrapper; +using js::UncheckedUnwrap; +using js::Wrapper; + +namespace xpc { + +#define Between(x, a, b) (a <= x && x <= b) + +static_assert(JSProto_URIError - JSProto_Error == 8, + "New prototype added in error object range"); +#define AssertErrorObjectKeyInBounds(key) \ + static_assert(Between(key, JSProto_Error, JSProto_URIError), \ + "We depend on js/ProtoKey.h ordering here"); +MOZ_FOR_EACH(AssertErrorObjectKeyInBounds, (), + (JSProto_Error, JSProto_InternalError, JSProto_AggregateError, + JSProto_EvalError, JSProto_RangeError, JSProto_ReferenceError, + JSProto_SyntaxError, JSProto_TypeError, JSProto_URIError)); + +static_assert(JSProto_Uint8ClampedArray - JSProto_Int8Array == 8, + "New prototype added in typed array range"); +#define AssertTypedArrayKeyInBounds(key) \ + static_assert(Between(key, JSProto_Int8Array, JSProto_Uint8ClampedArray), \ + "We depend on js/ProtoKey.h ordering here"); +MOZ_FOR_EACH(AssertTypedArrayKeyInBounds, (), + (JSProto_Int8Array, JSProto_Uint8Array, JSProto_Int16Array, + JSProto_Uint16Array, JSProto_Int32Array, JSProto_Uint32Array, + JSProto_Float32Array, JSProto_Float64Array, + JSProto_Uint8ClampedArray)); + +#undef Between + +inline bool IsErrorObjectKey(JSProtoKey key) { + return key >= JSProto_Error && key <= JSProto_URIError; +} + +inline bool IsTypedArrayKey(JSProtoKey key) { + return key >= JSProto_Int8Array && key <= JSProto_Uint8ClampedArray; +} + +// Whitelist for the standard ES classes we can Xray to. +static bool IsJSXraySupported(JSProtoKey key) { + if (IsTypedArrayKey(key)) { + return true; + } + if (IsErrorObjectKey(key)) { + return true; + } + switch (key) { + case JSProto_Date: + case JSProto_DataView: + case JSProto_Object: + case JSProto_Array: + case JSProto_Function: + case JSProto_BoundFunction: + case JSProto_TypedArray: + case JSProto_SavedFrame: + case JSProto_RegExp: + case JSProto_Promise: + case JSProto_ArrayBuffer: + case JSProto_SharedArrayBuffer: + case JSProto_Map: + case JSProto_Set: + case JSProto_WeakMap: + case JSProto_WeakSet: + return true; + default: + return false; + } +} + +XrayType GetXrayType(JSObject* obj) { + obj = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false); + if (mozilla::dom::UseDOMXray(obj)) { + return XrayForDOMObject; + } + + MOZ_ASSERT(!js::IsWindowProxy(obj)); + + JSProtoKey standardProto = IdentifyStandardInstanceOrPrototype(obj); + if (IsJSXraySupported(standardProto)) { + return XrayForJSObject; + } + + // Modulo a few exceptions, everything else counts as an XrayWrapper to an + // opaque object, which means that more-privileged code sees nothing from + // the underlying object. This is very important for security. In some cases + // though, we need to make an exception for compatibility. + if (IsSandbox(obj)) { + return NotXray; + } + + return XrayForOpaqueObject; +} + +JSObject* XrayAwareCalleeGlobal(JSObject* fun) { + MOZ_ASSERT(js::IsFunctionObject(fun)); + + if (!js::FunctionHasNativeReserved(fun)) { + // Just a normal function, no Xrays involved. + return JS::GetNonCCWObjectGlobal(fun); + } + + // The functions we expect here have the Xray wrapper they're associated with + // in their XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT and, in a debug build, + // themselves in their XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF. Assert that + // last bit. + MOZ_ASSERT(&js::GetFunctionNativeReserved( + fun, XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF) + .toObject() == fun); + + Value v = + js::GetFunctionNativeReserved(fun, XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT); + MOZ_ASSERT(IsXrayWrapper(&v.toObject())); + + JSObject* xrayTarget = js::UncheckedUnwrap(&v.toObject()); + return JS::GetNonCCWObjectGlobal(xrayTarget); +} + +JSObject* XrayTraits::getExpandoChain(HandleObject obj) { + return ObjectScope(obj)->GetExpandoChain(obj); +} + +JSObject* XrayTraits::detachExpandoChain(HandleObject obj) { + return ObjectScope(obj)->DetachExpandoChain(obj); +} + +bool XrayTraits::setExpandoChain(JSContext* cx, HandleObject obj, + HandleObject chain) { + return ObjectScope(obj)->SetExpandoChain(cx, obj, chain); +} + +const JSClass XrayTraits::HolderClass = { + "XrayHolder", JSCLASS_HAS_RESERVED_SLOTS(HOLDER_SHARED_SLOT_COUNT)}; + +const JSClass JSXrayTraits::HolderClass = { + "JSXrayHolder", JSCLASS_HAS_RESERVED_SLOTS(SLOT_COUNT)}; + +bool OpaqueXrayTraits::resolveOwnProperty( + JSContext* cx, HandleObject wrapper, HandleObject target, + HandleObject holder, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> desc) { + bool ok = + XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc); + if (!ok || desc.isSome()) { + return ok; + } + + return ReportWrapperDenial(cx, id, WrapperDenialForXray, + "object is not safely Xrayable"); +} + +bool ReportWrapperDenial(JSContext* cx, HandleId id, WrapperDenialType type, + const char* reason) { + RealmPrivate* priv = RealmPrivate::Get(CurrentGlobalOrNull(cx)); + bool alreadyWarnedOnce = priv->wrapperDenialWarnings[type]; + priv->wrapperDenialWarnings[type] = true; + + // The browser console warning is only emitted for the first violation, + // whereas the (debug-only) NS_WARNING is emitted for each violation. +#ifndef DEBUG + if (alreadyWarnedOnce) { + return true; + } +#endif + + nsAutoJSString propertyName; + RootedValue idval(cx); + if (!JS_IdToValue(cx, id, &idval)) { + return false; + } + JSString* str = JS_ValueToSource(cx, idval); + if (!str) { + return false; + } + if (!propertyName.init(cx, str)) { + return false; + } + AutoFilename filename; + uint32_t line = 0; + JS::ColumnNumberOneOrigin column; + DescribeScriptedCaller(cx, &filename, &line, &column); + + // Warn to the terminal for the logs. + NS_WARNING( + nsPrintfCString("Silently denied access to property %s: %s (@%s:%u:%u)", + NS_LossyConvertUTF16toASCII(propertyName).get(), reason, + filename.get(), line, column.oneOriginValue()) + .get()); + + // If this isn't the first warning on this topic for this global, we've + // already bailed out in opt builds. Now that the NS_WARNING is done, bail + // out in debug builds as well. + if (alreadyWarnedOnce) { + return true; + } + + // + // Log a message to the console service. + // + + // Grab the pieces. + nsCOMPtr<nsIConsoleService> consoleService = + do_GetService(NS_CONSOLESERVICE_CONTRACTID); + NS_ENSURE_TRUE(consoleService, true); + nsCOMPtr<nsIScriptError> errorObject = + do_CreateInstance(NS_SCRIPTERROR_CONTRACTID); + NS_ENSURE_TRUE(errorObject, true); + + // Compute the current window id if any. + uint64_t windowId = 0; + if (nsGlobalWindowInner* win = CurrentWindowOrNull(cx)) { + windowId = win->WindowID(); + } + + Maybe<nsPrintfCString> errorMessage; + if (type == WrapperDenialForXray) { + errorMessage.emplace( + "XrayWrapper denied access to property %s (reason: %s). " + "See https://developer.mozilla.org/en-US/docs/Xray_vision " + "for more information. Note that only the first denied " + "property access from a given global object will be reported.", + NS_LossyConvertUTF16toASCII(propertyName).get(), reason); + } else { + MOZ_ASSERT(type == WrapperDenialForCOW); + errorMessage.emplace( + "Security wrapper denied access to property %s on privileged " + "Javascript object. Note that only the first denied property " + "access from a given global object will be reported.", + NS_LossyConvertUTF16toASCII(propertyName).get()); + } + nsString filenameStr(NS_ConvertASCIItoUTF16(filename.get())); + nsresult rv = errorObject->InitWithWindowID( + NS_ConvertASCIItoUTF16(errorMessage.ref()), filenameStr, u""_ns, line, + column.oneOriginValue(), nsIScriptError::warningFlag, "XPConnect", + windowId); + NS_ENSURE_SUCCESS(rv, true); + rv = consoleService->LogMessage(errorObject); + NS_ENSURE_SUCCESS(rv, true); + + return true; +} + +bool JSXrayTraits::getOwnPropertyFromWrapperIfSafe( + JSContext* cx, HandleObject wrapper, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> outDesc) { + MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx)); + RootedObject target(cx, getTargetObject(wrapper)); + RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx)); + { + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, wrapperGlobal, id, + outDesc)) { + return false; + } + } + return JS_WrapPropertyDescriptor(cx, outDesc); +} + +bool JSXrayTraits::getOwnPropertyFromTargetIfSafe( + JSContext* cx, HandleObject target, HandleObject wrapper, + HandleObject wrapperGlobal, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> outDesc) { + // Note - This function operates in the target compartment, because it + // avoids a bunch of back-and-forth wrapping in enumerateNames. + MOZ_ASSERT(getTargetObject(wrapper) == target); + MOZ_ASSERT(js::IsObjectInContextCompartment(target, cx)); + MOZ_ASSERT(WrapperFactory::IsXrayWrapper(wrapper)); + MOZ_ASSERT(JS_IsGlobalObject(wrapperGlobal)); + js::AssertSameCompartment(wrapper, wrapperGlobal); + MOZ_ASSERT(outDesc.isNothing()); + + Rooted<Maybe<PropertyDescriptor>> desc(cx); + if (!JS_GetOwnPropertyDescriptorById(cx, target, id, &desc)) { + return false; + } + + // If the property doesn't exist at all, we're done. + if (desc.isNothing()) { + return true; + } + + // Disallow accessor properties. + if (desc->isAccessorDescriptor()) { + JSAutoRealm ar(cx, wrapperGlobal); + JS_MarkCrossZoneId(cx, id); + return ReportWrapperDenial(cx, id, WrapperDenialForXray, + "property has accessor"); + } + + // Apply extra scrutiny to objects. + if (desc->value().isObject()) { + RootedObject propObj(cx, js::UncheckedUnwrap(&desc->value().toObject())); + JSAutoRealm ar(cx, propObj); + + // Disallow non-subsumed objects. + if (!AccessCheck::subsumes(target, propObj)) { + JSAutoRealm ar(cx, wrapperGlobal); + JS_MarkCrossZoneId(cx, id); + return ReportWrapperDenial(cx, id, WrapperDenialForXray, + "value not same-origin with target"); + } + + // Disallow non-Xrayable objects. + XrayType xrayType = GetXrayType(propObj); + if (xrayType == NotXray || xrayType == XrayForOpaqueObject) { + JSAutoRealm ar(cx, wrapperGlobal); + JS_MarkCrossZoneId(cx, id); + return ReportWrapperDenial(cx, id, WrapperDenialForXray, + "value not Xrayable"); + } + + // Disallow callables. + if (JS::IsCallable(propObj)) { + JSAutoRealm ar(cx, wrapperGlobal); + JS_MarkCrossZoneId(cx, id); + return ReportWrapperDenial(cx, id, WrapperDenialForXray, + "value is callable"); + } + } + + // Disallow any property that shadows something on its (Xrayed) + // prototype chain. + JSAutoRealm ar2(cx, wrapperGlobal); + JS_MarkCrossZoneId(cx, id); + RootedObject proto(cx); + bool foundOnProto = false; + if (!JS_GetPrototype(cx, wrapper, &proto) || + (proto && !JS_HasPropertyById(cx, proto, id, &foundOnProto))) { + return false; + } + if (foundOnProto) { + return ReportWrapperDenial( + cx, id, WrapperDenialForXray, + "value shadows a property on the standard prototype"); + } + + // We made it! Assign over the descriptor, and don't forget to wrap. + outDesc.set(desc); + return true; +} + +// Returns true on success (in the JSAPI sense), false on failure. If true is +// returned, desc.object() will indicate whether we actually resolved +// the property. +// +// id is the property id we're looking for. +// holder is the object to define the property on. +// fs is the relevant JSFunctionSpec*. +// ps is the relevant JSPropertySpec*. +// desc is the descriptor we're resolving into. +static bool TryResolvePropertyFromSpecs( + JSContext* cx, HandleId id, HandleObject holder, const JSFunctionSpec* fs, + const JSPropertySpec* ps, MutableHandle<Maybe<PropertyDescriptor>> desc) { + // Scan through the functions. + const JSFunctionSpec* fsMatch = nullptr; + for (; fs && fs->name; ++fs) { + if (PropertySpecNameEqualsId(fs->name, id)) { + fsMatch = fs; + break; + } + } + if (fsMatch) { + // Generate an Xrayed version of the method. + RootedFunction fun(cx, JS::NewFunctionFromSpec(cx, fsMatch, id)); + if (!fun) { + return false; + } + + // The generic Xray machinery only defines non-own properties of the target + // on the holder. This is broken, and will be fixed at some point, but for + // now we need to cache the value explicitly. See the corresponding call to + // JS_GetOwnPropertyDescriptorById at the top of + // JSXrayTraits::resolveOwnProperty. + RootedObject funObj(cx, JS_GetFunctionObject(fun)); + return JS_DefinePropertyById(cx, holder, id, funObj, 0) && + JS_GetOwnPropertyDescriptorById(cx, holder, id, desc); + } + + // Scan through the properties. + const JSPropertySpec* psMatch = nullptr; + for (; ps && ps->name; ++ps) { + if (PropertySpecNameEqualsId(ps->name, id)) { + psMatch = ps; + break; + } + } + if (psMatch) { + // The generic Xray machinery only defines non-own properties on the holder. + // This is broken, and will be fixed at some point, but for now we need to + // cache the value explicitly. See the corresponding call to + // JS_GetPropertyById at the top of JSXrayTraits::resolveOwnProperty. + // + // Note also that the public-facing API here doesn't give us a way to + // pass along JITInfo. It's probably ok though, since Xrays are already + // pretty slow. + + unsigned attrs = psMatch->attributes(); + if (psMatch->isAccessor()) { + if (psMatch->isSelfHosted()) { + JSFunction* getterFun = JS::GetSelfHostedFunction( + cx, psMatch->u.accessors.getter.selfHosted.funname, id, 0); + if (!getterFun) { + return false; + } + RootedObject getterObj(cx, JS_GetFunctionObject(getterFun)); + RootedObject setterObj(cx); + if (psMatch->u.accessors.setter.selfHosted.funname) { + JSFunction* setterFun = JS::GetSelfHostedFunction( + cx, psMatch->u.accessors.setter.selfHosted.funname, id, 0); + if (!setterFun) { + return false; + } + setterObj = JS_GetFunctionObject(setterFun); + } + if (!JS_DefinePropertyById(cx, holder, id, getterObj, setterObj, + attrs)) { + return false; + } + } else { + if (!JS_DefinePropertyById( + cx, holder, id, psMatch->u.accessors.getter.native.op, + psMatch->u.accessors.setter.native.op, attrs)) { + return false; + } + } + } else { + RootedValue v(cx); + if (!psMatch->getValue(cx, &v)) { + return false; + } + if (!JS_DefinePropertyById(cx, holder, id, v, attrs)) { + return false; + } + } + + return JS_GetOwnPropertyDescriptorById(cx, holder, id, desc); + } + + return true; +} + +static bool ShouldResolvePrototypeProperty(JSProtoKey key) { + // Proxy constructors have no "prototype" property. + return key != JSProto_Proxy; +} + +static bool ShouldResolveStaticProperties(JSProtoKey key) { + if (!IsJSXraySupported(key)) { + // If we can't Xray this ES class, then we can't resolve statics on it. + return false; + } + + // Don't try to resolve static properties on RegExp, because they + // have issues. In particular, some of them grab state off the + // global of the RegExp constructor that describes the last regexp + // evaluation in that global, which is not a useful thing to do + // over Xrays. + return key != JSProto_RegExp; +} + +bool JSXrayTraits::resolveOwnProperty( + JSContext* cx, HandleObject wrapper, HandleObject target, + HandleObject holder, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> desc) { + // Call the common code. + bool ok = + XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc); + if (!ok || desc.isSome()) { + return ok; + } + + // The non-HasPrototypes semantics implemented by traditional Xrays are kind + // of broken with respect to |own|-ness and the holder. The common code + // muddles through by only checking the holder for non-|own| lookups, but + // that doesn't work for us. So we do an explicit holder check here, and hope + // that this mess gets fixed up soon. + if (!JS_GetOwnPropertyDescriptorById(cx, holder, id, desc)) { + return false; + } + if (desc.isSome()) { + return true; + } + + JSProtoKey key = getProtoKey(holder); + if (!isPrototype(holder)) { + // For Object and Array instances, we expose some properties from the + // underlying object, but only after filtering them carefully. + // + // Note that, as far as JS observables go, Arrays are just Objects with + // a different prototype and a magic (own, non-configurable) |.length| that + // serves as a non-tight upper bound on |own| indexed properties. So while + // it's tempting to try to impose some sort of structure on what Arrays + // "should" look like over Xrays, the underlying object is squishy enough + // that it makes sense to just treat them like Objects for Xray purposes. + if (key == JSProto_Object || key == JSProto_Array) { + return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc); + } + if (IsTypedArrayKey(key)) { + if (IsArrayIndex(GetArrayIndexFromId(id))) { + // WebExtensions can't use cloneInto(), so we just let them do + // the slow thing to maximize compatibility. + if (CompartmentPrivate::Get(CurrentGlobalOrNull(cx)) + ->isWebExtensionContentScript) { + Rooted<Maybe<PropertyDescriptor>> innerDesc(cx); + { + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + if (!JS_GetOwnPropertyDescriptorById(cx, target, id, &innerDesc)) { + return false; + } + } + if (innerDesc.isSome() && innerDesc->isDataDescriptor() && + innerDesc->value().isNumber()) { + desc.set(innerDesc); + } + return true; + } + JS_ReportErrorASCII( + cx, + "Accessing TypedArray data over Xrays is slow, and forbidden " + "in order to encourage performant code. To copy TypedArrays " + "across origin boundaries, consider using " + "Components.utils.cloneInto()."); + return false; + } + } else if (key == JSProto_Function) { + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH)) { + uint16_t length; + RootedFunction fun(cx, JS_GetObjectFunction(target)); + { + JSAutoRealm ar(cx, target); + if (!JS_GetFunctionLength(cx, fun, &length)) { + return false; + } + } + desc.set(Some(PropertyDescriptor::Data(NumberValue(length), {}))); + return true; + } + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_NAME)) { + JS::Rooted<JSFunction*> fun(cx, JS_GetObjectFunction(target)); + JS::Rooted<JSString*> fname(cx); + if (!JS_GetFunctionId(cx, fun, &fname)) { + return false; + } + if (fname) { + JS_MarkCrossZoneIdValue(cx, StringValue(fname)); + } + desc.set(Some(PropertyDescriptor::Data( + fname ? StringValue(fname) : JS_GetEmptyStringValue(cx), {}))); + } else { + // Look for various static properties/methods and the + // 'prototype' property. + JSProtoKey standardConstructor = constructorFor(holder); + if (standardConstructor != JSProto_Null) { + // Handle the 'prototype' property to make + // xrayedGlobal.StandardClass.prototype work. + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_PROTOTYPE) && + ShouldResolvePrototypeProperty(standardConstructor)) { + RootedObject standardProto(cx); + { + JSAutoRealm ar(cx, target); + if (!JS_GetClassPrototype(cx, standardConstructor, + &standardProto)) { + return false; + } + MOZ_ASSERT(standardProto); + } + + if (!JS_WrapObject(cx, &standardProto)) { + return false; + } + desc.set(Some( + PropertyDescriptor::Data(ObjectValue(*standardProto), {}))); + return true; + } + + if (ShouldResolveStaticProperties(standardConstructor)) { + const JSClass* clasp = js::ProtoKeyToClass(standardConstructor); + MOZ_ASSERT(clasp->specDefined()); + + if (!TryResolvePropertyFromSpecs( + cx, id, holder, clasp->specConstructorFunctions(), + clasp->specConstructorProperties(), desc)) { + return false; + } + + if (desc.isSome()) { + return true; + } + } + } + } + } else if (IsErrorObjectKey(key)) { + // The useful state of error objects (except for .stack) is + // (unfortunately) represented as own data properties per-spec. This + // means that we can't have a a clean representation of the data + // (free from tampering) without doubling the slots of Error + // objects, which isn't great. So we forward these properties to the + // underlying object and then just censor any values with the wrong + // type. This limits the ability of content to do anything all that + // confusing. + bool isErrorIntProperty = + id == GetJSIDByIndex(cx, XPCJSContext::IDX_LINENUMBER) || + id == GetJSIDByIndex(cx, XPCJSContext::IDX_COLUMNNUMBER); + bool isErrorStringProperty = + id == GetJSIDByIndex(cx, XPCJSContext::IDX_FILENAME) || + id == GetJSIDByIndex(cx, XPCJSContext::IDX_MESSAGE); + if (isErrorIntProperty || isErrorStringProperty) { + RootedObject waiver(cx, wrapper); + if (!WrapperFactory::WaiveXrayAndWrap(cx, &waiver)) { + return false; + } + if (!JS_GetOwnPropertyDescriptorById(cx, waiver, id, desc)) { + return false; + } + if (desc.isSome()) { + // Make sure the property has the expected type. + if (!desc->isDataDescriptor() || + (isErrorIntProperty && !desc->value().isInt32()) || + (isErrorStringProperty && !desc->value().isString())) { + desc.reset(); + } + } + return true; + } + +#if defined(NIGHTLY_BUILD) + // The optional .cause property can have any value. + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_CAUSE)) { + return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc); + } +#endif + + if (key == JSProto_AggregateError && + id == GetJSIDByIndex(cx, XPCJSContext::IDX_ERRORS)) { + return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc); + } + } else if (key == JSProto_RegExp) { + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_LASTINDEX)) { + return getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc); + } + } else if (key == JSProto_BoundFunction) { + // Bound functions have configurable .name and .length own data + // properties. Only support string values for .name and number values for + // .length. + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_NAME)) { + if (!getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc)) { + return false; + } + if (desc.isSome() && + (!desc->isDataDescriptor() || !desc->value().isString())) { + desc.reset(); + } + return true; + } + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH)) { + if (!getOwnPropertyFromWrapperIfSafe(cx, wrapper, id, desc)) { + return false; + } + if (desc.isSome() && + (!desc->isDataDescriptor() || !desc->value().isNumber())) { + desc.reset(); + } + return true; + } + } + + // The rest of this function applies only to prototypes. + return true; + } + + // Handle the 'constructor' property. + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_CONSTRUCTOR)) { + RootedObject constructor(cx); + { + JSAutoRealm ar(cx, target); + if (!JS_GetClassObject(cx, key, &constructor)) { + return false; + } + } + if (!JS_WrapObject(cx, &constructor)) { + return false; + } + desc.set(Some(PropertyDescriptor::Data( + ObjectValue(*constructor), + {PropertyAttribute::Configurable, PropertyAttribute::Writable}))); + return true; + } + + if (ShouldIgnorePropertyDefinition(cx, key, id)) { + MOZ_ASSERT(desc.isNothing()); + return true; + } + + // Grab the JSClass. We require all Xrayable classes to have a ClassSpec. + const JSClass* clasp = JS::GetClass(target); + MOZ_ASSERT(clasp->specDefined()); + + // Indexed array properties are handled above, so we can just work with the + // class spec here. + return TryResolvePropertyFromSpecs(cx, id, holder, + clasp->specPrototypeFunctions(), + clasp->specPrototypeProperties(), desc); +} + +bool JSXrayTraits::delete_(JSContext* cx, HandleObject wrapper, HandleId id, + ObjectOpResult& result) { + MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx)); + + RootedObject holder(cx, ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + // If we're using Object Xrays, we allow callers to attempt to delete any + // property from the underlying object that they are able to resolve. Note + // that this deleting may fail if the property is non-configurable. + JSProtoKey key = getProtoKey(holder); + bool isObjectOrArrayInstance = + (key == JSProto_Object || key == JSProto_Array) && !isPrototype(holder); + if (isObjectOrArrayInstance) { + RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx)); + RootedObject target(cx, getTargetObject(wrapper)); + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + Rooted<Maybe<PropertyDescriptor>> desc(cx); + if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, wrapperGlobal, id, + &desc)) { + return false; + } + if (desc.isSome()) { + return JS_DeletePropertyById(cx, target, id, result); + } + } + return result.succeed(); +} + +bool JSXrayTraits::defineProperty( + JSContext* cx, HandleObject wrapper, HandleId id, + Handle<PropertyDescriptor> desc, + Handle<Maybe<PropertyDescriptor>> existingDesc, + Handle<JSObject*> existingHolder, ObjectOpResult& result, bool* defined) { + *defined = false; + RootedObject holder(cx, ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + // Object and Array instances are special. For those cases, we forward + // property definitions to the underlying object if the following + // conditions are met: + // * The property being defined is a value-prop. + // * The property being defined is either a primitive or subsumed by the + // target. + // * As seen from the Xray, any existing property that we would overwrite + // is an |own| value-prop. + // + // To avoid confusion, we disallow expandos on Object and Array instances, and + // therefore raise an exception here if the above conditions aren't met. + JSProtoKey key = getProtoKey(holder); + bool isInstance = !isPrototype(holder); + bool isObjectOrArray = (key == JSProto_Object || key == JSProto_Array); + if (isObjectOrArray && isInstance) { + RootedObject target(cx, getTargetObject(wrapper)); + if (desc.isAccessorDescriptor()) { + JS_ReportErrorASCII(cx, + "Not allowed to define accessor property on [Object] " + "or [Array] XrayWrapper"); + return false; + } + if (desc.value().isObject() && + !AccessCheck::subsumes(target, + js::UncheckedUnwrap(&desc.value().toObject()))) { + JS_ReportErrorASCII(cx, + "Not allowed to define cross-origin object as " + "property on [Object] or [Array] XrayWrapper"); + return false; + } + if (existingDesc.isSome()) { + if (existingDesc->isAccessorDescriptor()) { + JS_ReportErrorASCII(cx, + "Not allowed to overwrite accessor property on " + "[Object] or [Array] XrayWrapper"); + return false; + } + if (existingHolder != wrapper) { + JS_ReportErrorASCII(cx, + "Not allowed to shadow non-own Xray-resolved " + "property on [Object] or [Array] XrayWrapper"); + return false; + } + } + + Rooted<PropertyDescriptor> wrappedDesc(cx, desc); + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + if (!JS_WrapPropertyDescriptor(cx, &wrappedDesc) || + !JS_DefinePropertyById(cx, target, id, wrappedDesc, result)) { + return false; + } + *defined = true; + return true; + } + + // For WebExtensions content scripts, we forward the definition of indexed + // properties. By validating that the key and value are both numbers, we can + // avoid doing any wrapping. + if (isInstance && IsTypedArrayKey(key) && + CompartmentPrivate::Get(JS::CurrentGlobalOrNull(cx)) + ->isWebExtensionContentScript && + desc.isDataDescriptor() && + (desc.value().isNumber() || desc.value().isUndefined()) && + IsArrayIndex(GetArrayIndexFromId(id))) { + RootedObject target(cx, getTargetObject(wrapper)); + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + if (!JS_DefinePropertyById(cx, target, id, desc, result)) { + return false; + } + *defined = true; + return true; + } + + return true; +} + +static bool MaybeAppend(jsid id, unsigned flags, MutableHandleIdVector props) { + MOZ_ASSERT(!(flags & JSITER_SYMBOLSONLY)); + if (!(flags & JSITER_SYMBOLS) && id.isSymbol()) { + return true; + } + return props.append(id); +} + +// Append the names from the given function and property specs to props. +static bool AppendNamesFromFunctionAndPropertySpecs( + JSContext* cx, JSProtoKey key, const JSFunctionSpec* fs, + const JSPropertySpec* ps, unsigned flags, MutableHandleIdVector props) { + // Convert the method and property names to jsids and pass them to the caller. + for (; fs && fs->name; ++fs) { + jsid id; + if (!PropertySpecNameToPermanentId(cx, fs->name, &id)) { + return false; + } + if (!js::ShouldIgnorePropertyDefinition(cx, key, id)) { + if (!MaybeAppend(id, flags, props)) { + return false; + } + } + } + for (; ps && ps->name; ++ps) { + jsid id; + if (!PropertySpecNameToPermanentId(cx, ps->name, &id)) { + return false; + } + if (!js::ShouldIgnorePropertyDefinition(cx, key, id)) { + if (!MaybeAppend(id, flags, props)) { + return false; + } + } + } + + return true; +} + +bool JSXrayTraits::enumerateNames(JSContext* cx, HandleObject wrapper, + unsigned flags, MutableHandleIdVector props) { + MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx)); + + RootedObject target(cx, getTargetObject(wrapper)); + RootedObject holder(cx, ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + JSProtoKey key = getProtoKey(holder); + if (!isPrototype(holder)) { + // For Object and Array instances, we expose some properties from the + // underlying object, but only after filtering them carefully. + if (key == JSProto_Object || key == JSProto_Array) { + MOZ_ASSERT(props.empty()); + RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx)); + { + JSAutoRealm ar(cx, target); + RootedIdVector targetProps(cx); + if (!js::GetPropertyKeys(cx, target, flags | JSITER_OWNONLY, + &targetProps)) { + return false; + } + // Loop over the properties, and only pass along the ones that + // we determine to be safe. + if (!props.reserve(targetProps.length())) { + return false; + } + for (size_t i = 0; i < targetProps.length(); ++i) { + Rooted<Maybe<PropertyDescriptor>> desc(cx); + RootedId id(cx, targetProps[i]); + if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, + wrapperGlobal, id, &desc)) { + return false; + } + if (desc.isSome()) { + props.infallibleAppend(id); + } + } + } + for (size_t i = 0; i < props.length(); ++i) { + JS_MarkCrossZoneId(cx, props[i]); + } + return true; + } + if (IsTypedArrayKey(key)) { + size_t length = JS_GetTypedArrayLength(target); + // TypedArrays enumerate every indexed property in range, but + // |length| is a getter that lives on the proto, like it should be. + + // Fail early if the typed array is enormous, because this will be very + // slow and will likely report OOM. This also means we don't need to + // handle indices greater than PropertyKey::IntMax in the loop below. + static_assert(PropertyKey::IntMax >= INT32_MAX); + if (length > INT32_MAX) { + JS_ReportOutOfMemory(cx); + return false; + } + + if (!props.reserve(length)) { + return false; + } + for (int32_t i = 0; i < int32_t(length); ++i) { + props.infallibleAppend(PropertyKey::Int(i)); + } + } else if (key == JSProto_Function) { + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH))) { + return false; + } + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_NAME))) { + return false; + } + // Handle the .prototype property and static properties on standard + // constructors. + JSProtoKey standardConstructor = constructorFor(holder); + if (standardConstructor != JSProto_Null) { + if (ShouldResolvePrototypeProperty(standardConstructor)) { + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_PROTOTYPE))) { + return false; + } + } + + if (ShouldResolveStaticProperties(standardConstructor)) { + const JSClass* clasp = js::ProtoKeyToClass(standardConstructor); + MOZ_ASSERT(clasp->specDefined()); + + if (!AppendNamesFromFunctionAndPropertySpecs( + cx, key, clasp->specConstructorFunctions(), + clasp->specConstructorProperties(), flags, props)) { + return false; + } + } + } + } else if (IsErrorObjectKey(key)) { + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_FILENAME)) || + !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LINENUMBER)) || + !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_COLUMNNUMBER)) || + !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_STACK)) || + !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_MESSAGE))) { + return false; + } + } else if (key == JSProto_RegExp) { + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LASTINDEX))) { + return false; + } + } else if (key == JSProto_BoundFunction) { + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_LENGTH)) || + !props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_NAME))) { + return false; + } + } + + // The rest of this function applies only to prototypes. + return true; + } + + // Add the 'constructor' property. + if (!props.append(GetJSIDByIndex(cx, XPCJSContext::IDX_CONSTRUCTOR))) { + return false; + } + + // Grab the JSClass. We require all Xrayable classes to have a ClassSpec. + const JSClass* clasp = JS::GetClass(target); + MOZ_ASSERT(clasp->specDefined()); + + return AppendNamesFromFunctionAndPropertySpecs( + cx, key, clasp->specPrototypeFunctions(), + clasp->specPrototypeProperties(), flags, props); +} + +bool JSXrayTraits::construct(JSContext* cx, HandleObject wrapper, + const JS::CallArgs& args, + const js::Wrapper& baseInstance) { + JSXrayTraits& self = JSXrayTraits::singleton; + JS::RootedObject holder(cx, self.ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + const JSProtoKey key = xpc::JSXrayTraits::getProtoKey(holder); + if (key == JSProto_Function) { + JSProtoKey standardConstructor = constructorFor(holder); + if (standardConstructor == JSProto_Null) { + return baseInstance.construct(cx, wrapper, args); + } + + const JSClass* clasp = js::ProtoKeyToClass(standardConstructor); + MOZ_ASSERT(clasp); + if (!(clasp->flags & JSCLASS_HAS_XRAYED_CONSTRUCTOR)) { + return baseInstance.construct(cx, wrapper, args); + } + + // If the JSCLASS_HAS_XRAYED_CONSTRUCTOR flag is set on the Class, + // we don't use the constructor at hand. Instead, we retrieve the + // equivalent standard constructor in the xray compartment and run + // it in that compartment. The newTarget isn't unwrapped, and the + // constructor has to be able to detect and handle this situation. + // See the comments in js/public/Class.h and PromiseConstructor for + // details and an example. + RootedObject ctor(cx); + if (!JS_GetClassObject(cx, standardConstructor, &ctor)) { + return false; + } + + RootedValue ctorVal(cx, ObjectValue(*ctor)); + HandleValueArray vals(args); + RootedObject result(cx); + if (!JS::Construct(cx, ctorVal, wrapper, vals, &result)) { + return false; + } + AssertSameCompartment(cx, result); + args.rval().setObject(*result); + return true; + } + if (key == JSProto_BoundFunction) { + return baseInstance.construct(cx, wrapper, args); + } + + JS::RootedValue v(cx, JS::ObjectValue(*wrapper)); + js::ReportIsNotFunction(cx, v); + return false; +} + +JSObject* JSXrayTraits::createHolder(JSContext* cx, JSObject* wrapper) { + RootedObject target(cx, getTargetObject(wrapper)); + RootedObject holder(cx, + JS_NewObjectWithGivenProto(cx, &HolderClass, nullptr)); + if (!holder) { + return nullptr; + } + + // Compute information about the target. + bool isPrototype = false; + JSProtoKey key = IdentifyStandardInstance(target); + if (key == JSProto_Null) { + isPrototype = true; + key = IdentifyStandardPrototype(target); + } + MOZ_ASSERT(key != JSProto_Null); + + // Special case: pretend Arguments objects are arrays for Xrays. + // + // Arguments objects are strange beasts - they inherit Object.prototype, + // and implement iteration by defining an |own| property for + // Symbol.iterator. Since this value is callable, Array/Object Xrays will + // filter it out, causing the Xray view to be non-iterable, which in turn + // breaks consumers. + // + // We can't trust the iterator value from the content compartment, + // but the generic one on Array.prototype works well enough. So we force + // the Xray view of Arguments objects to inherit Array.prototype, which + // in turn allows iteration via the inherited + // Array.prototype[Symbol.iterator]. This doesn't emulate any of the weird + // semantics of Arguments iterators, but is probably good enough. + // + // Note that there are various Xray traps that do other special behavior for + // JSProto_Array, but they also provide that special behavior for + // JSProto_Object, and since Arguments would otherwise get JSProto_Object, + // this does not cause any behavior change at those sites. + if (key == JSProto_Object && js::IsArgumentsObject(target)) { + key = JSProto_Array; + } + + // Store it on the holder. + RootedValue v(cx); + v.setNumber(static_cast<uint32_t>(key)); + JS::SetReservedSlot(holder, SLOT_PROTOKEY, v); + v.setBoolean(isPrototype); + JS::SetReservedSlot(holder, SLOT_ISPROTOTYPE, v); + + // If this is a function, also compute whether it serves as a constructor + // for a standard class. + if (key == JSProto_Function) { + v.setNumber(static_cast<uint32_t>(IdentifyStandardConstructor(target))); + JS::SetReservedSlot(holder, SLOT_CONSTRUCTOR_FOR, v); + } + + return holder; +} + +DOMXrayTraits DOMXrayTraits::singleton; +JSXrayTraits JSXrayTraits::singleton; +OpaqueXrayTraits OpaqueXrayTraits::singleton; + +XrayTraits* GetXrayTraits(JSObject* obj) { + switch (GetXrayType(obj)) { + case XrayForDOMObject: + return &DOMXrayTraits::singleton; + case XrayForJSObject: + return &JSXrayTraits::singleton; + case XrayForOpaqueObject: + return &OpaqueXrayTraits::singleton; + default: + return nullptr; + } +} + +/* + * Xray expando handling. + * + * We hang expandos for Xray wrappers off a reserved slot on the target object + * so that same-origin compartments can share expandos for a given object. We + * have a linked list of expando objects, one per origin. The properties on + * these objects are generally wrappers pointing back to the compartment that + * applied them. + * + * The expando objects should _never_ be exposed to script. The fact that they + * live in the target compartment is a detail of the implementation, and does + * not imply that code in the target compartment should be allowed to inspect + * them. They are private to the origin that placed them. + */ + +// Certain compartments do not share expandos with other compartments. Xrays in +// these compartments cache expandos on the wrapper's holder, as there is only +// one such wrapper which can create or access the expando. This allows for +// faster access to the expando, including through JIT inline caches. +static inline bool CompartmentHasExclusiveExpandos(JSObject* obj) { + JS::Compartment* comp = JS::GetCompartment(obj); + CompartmentPrivate* priv = CompartmentPrivate::Get(comp); + return priv && priv->hasExclusiveExpandos; +} + +static inline JSObject* GetCachedXrayExpando(JSObject* wrapper); + +static inline void SetCachedXrayExpando(JSObject* holder, + JSObject* expandoWrapper); + +static nsIPrincipal* WrapperPrincipal(JSObject* obj) { + // Use the principal stored in CompartmentOriginInfo. That works because + // consumers are only interested in the origin-ignoring-document.domain. + // See expandoObjectMatchesConsumer. + MOZ_ASSERT(IsXrayWrapper(obj)); + JS::Compartment* comp = JS::GetCompartment(obj); + CompartmentPrivate* priv = CompartmentPrivate::Get(comp); + return priv->originInfo.GetPrincipalIgnoringDocumentDomain(); +} + +static nsIPrincipal* GetExpandoObjectPrincipal(JSObject* expandoObject) { + Value v = JS::GetReservedSlot(expandoObject, JSSLOT_EXPANDO_ORIGIN); + return static_cast<nsIPrincipal*>(v.toPrivate()); +} + +static void ExpandoObjectFinalize(JS::GCContext* gcx, JSObject* obj) { + // Release the principal. + nsIPrincipal* principal = GetExpandoObjectPrincipal(obj); + NS_RELEASE(principal); +} + +const JSClassOps XrayExpandoObjectClassOps = { + nullptr, // addProperty + nullptr, // delProperty + nullptr, // enumerate + nullptr, // newEnumerate + nullptr, // resolve + nullptr, // mayResolve + ExpandoObjectFinalize, // finalize + nullptr, // call + nullptr, // construct + nullptr, // trace +}; + +bool XrayTraits::expandoObjectMatchesConsumer(JSContext* cx, + HandleObject expandoObject, + nsIPrincipal* consumerOrigin) { + MOZ_ASSERT(js::IsObjectInContextCompartment(expandoObject, cx)); + + // First, compare the principals. + nsIPrincipal* o = GetExpandoObjectPrincipal(expandoObject); + // Note that it's very important here to ignore document.domain. We + // pull the principal for the expando object off of the first consumer + // for a given origin, and freely share the expandos amongst multiple + // same-origin consumers afterwards. However, this means that we have + // no way to know whether _all_ consumers have opted in to collaboration + // by explicitly setting document.domain. So we just mandate that expando + // sharing is unaffected by it. + if (!consumerOrigin->Equals(o)) { + return false; + } + + // Certain globals exclusively own the associated expandos, in which case + // the caller should have used the cached expando on the wrapper instead. + JSObject* owner = JS::GetReservedSlot(expandoObject, + JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER) + .toObjectOrNull(); + return owner == nullptr; +} + +bool XrayTraits::getExpandoObjectInternal(JSContext* cx, JSObject* expandoChain, + HandleObject exclusiveWrapper, + nsIPrincipal* origin, + MutableHandleObject expandoObject) { + MOZ_ASSERT(!JS_IsExceptionPending(cx)); + expandoObject.set(nullptr); + + // Use the cached expando if this wrapper has exclusive access to it. + if (exclusiveWrapper) { + JSObject* expandoWrapper = GetCachedXrayExpando(exclusiveWrapper); + expandoObject.set(expandoWrapper ? UncheckedUnwrap(expandoWrapper) + : nullptr); +#ifdef DEBUG + // Make sure the expando we found is on the target's chain. While we + // don't use this chain to look up expandos for the wrapper, + // the expando still needs to be on the chain to keep the wrapper and + // expando alive. + if (expandoObject) { + JSObject* head = expandoChain; + while (head && head != expandoObject) { + head = JS::GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull(); + } + MOZ_ASSERT(head == expandoObject); + } +#endif + return true; + } + + // The expando object lives in the compartment of the target, so all our + // work needs to happen there. + RootedObject head(cx, expandoChain); + JSAutoRealm ar(cx, head); + + // Iterate through the chain, looking for a same-origin object. + while (head) { + if (expandoObjectMatchesConsumer(cx, head, origin)) { + expandoObject.set(head); + return true; + } + head = JS::GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull(); + } + + // Not found. + return true; +} + +bool XrayTraits::getExpandoObject(JSContext* cx, HandleObject target, + HandleObject consumer, + MutableHandleObject expandoObject) { + // Return early if no expando object has ever been attached, which is + // usually the case. + JSObject* chain = getExpandoChain(target); + if (!chain) { + return true; + } + + bool isExclusive = CompartmentHasExclusiveExpandos(consumer); + return getExpandoObjectInternal(cx, chain, isExclusive ? consumer : nullptr, + WrapperPrincipal(consumer), expandoObject); +} + +// Wrappers which have exclusive access to the expando on their target object +// need to be kept alive as long as the target object exists. This is done by +// keeping the expando in the expando chain on the target (even though it will +// not be used while looking up the expando for the wrapper), and keeping a +// strong reference from that expando to the wrapper itself, via the +// JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER reserved slot. This slot does not +// point to the wrapper itself, because it is a cross compartment edge and we +// can't create a wrapper for a wrapper. Instead, the slot points to an +// instance of the holder class below in the wrapper's compartment, and the +// wrapper is held via this holder object's reserved slot. +static const JSClass gWrapperHolderClass = {"XrayExpandoWrapperHolder", + JSCLASS_HAS_RESERVED_SLOTS(1)}; +static const size_t JSSLOT_WRAPPER_HOLDER_CONTENTS = 0; + +JSObject* XrayTraits::attachExpandoObject(JSContext* cx, HandleObject target, + HandleObject exclusiveWrapper, + HandleObject exclusiveWrapperGlobal, + nsIPrincipal* origin) { + // Make sure the compartments are sane. + MOZ_ASSERT(js::IsObjectInContextCompartment(target, cx)); + if (exclusiveWrapper) { + MOZ_ASSERT(!js::IsObjectInContextCompartment(exclusiveWrapper, cx)); + MOZ_ASSERT(JS_IsGlobalObject(exclusiveWrapperGlobal)); + js::AssertSameCompartment(exclusiveWrapper, exclusiveWrapperGlobal); + } + + // No duplicates allowed. +#ifdef DEBUG + { + JSObject* chain = getExpandoChain(target); + if (chain) { + RootedObject existingExpandoObject(cx); + if (getExpandoObjectInternal(cx, chain, exclusiveWrapper, origin, + &existingExpandoObject)) { + MOZ_ASSERT(!existingExpandoObject); + } else { + JS_ClearPendingException(cx); + } + } + } +#endif + + // Create the expando object. + const JSClass* expandoClass = getExpandoClass(cx, target); + MOZ_ASSERT(!strcmp(expandoClass->name, "XrayExpandoObject")); + RootedObject expandoObject( + cx, JS_NewObjectWithGivenProto(cx, expandoClass, nullptr)); + if (!expandoObject) { + return nullptr; + } + + // AddRef and store the principal. + NS_ADDREF(origin); + JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_ORIGIN, + JS::PrivateValue(origin)); + + // Note the exclusive wrapper, if there is one. + RootedObject wrapperHolder(cx); + if (exclusiveWrapper) { + JSAutoRealm ar(cx, exclusiveWrapperGlobal); + wrapperHolder = + JS_NewObjectWithGivenProto(cx, &gWrapperHolderClass, nullptr); + if (!wrapperHolder) { + return nullptr; + } + JS_SetReservedSlot(wrapperHolder, JSSLOT_WRAPPER_HOLDER_CONTENTS, + ObjectValue(*exclusiveWrapper)); + } + if (!JS_WrapObject(cx, &wrapperHolder)) { + return nullptr; + } + JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER, + ObjectOrNullValue(wrapperHolder)); + + // Store it on the exclusive wrapper, if there is one. + if (exclusiveWrapper) { + RootedObject cachedExpandoObject(cx, expandoObject); + JSAutoRealm ar(cx, exclusiveWrapperGlobal); + if (!JS_WrapObject(cx, &cachedExpandoObject)) { + return nullptr; + } + JSObject* holder = ensureHolder(cx, exclusiveWrapper); + if (!holder) { + return nullptr; + } + SetCachedXrayExpando(holder, cachedExpandoObject); + } + + // If this is our first expando object, take the opportunity to preserve + // the wrapper. This keeps our expandos alive even if the Xray wrapper gets + // collected. + RootedObject chain(cx, getExpandoChain(target)); + if (!chain) { + preserveWrapper(target); + } + + // Insert it at the front of the chain. + JS_SetReservedSlot(expandoObject, JSSLOT_EXPANDO_NEXT, + ObjectOrNullValue(chain)); + setExpandoChain(cx, target, expandoObject); + + return expandoObject; +} + +JSObject* XrayTraits::ensureExpandoObject(JSContext* cx, HandleObject wrapper, + HandleObject target) { + MOZ_ASSERT(js::IsObjectInContextCompartment(wrapper, cx)); + RootedObject wrapperGlobal(cx, JS::CurrentGlobalOrNull(cx)); + + // Expando objects live in the target compartment. + JSAutoRealm ar(cx, target); + RootedObject expandoObject(cx); + if (!getExpandoObject(cx, target, wrapper, &expandoObject)) { + return nullptr; + } + if (!expandoObject) { + bool isExclusive = CompartmentHasExclusiveExpandos(wrapper); + expandoObject = + attachExpandoObject(cx, target, isExclusive ? wrapper : nullptr, + wrapperGlobal, WrapperPrincipal(wrapper)); + } + return expandoObject; +} + +bool XrayTraits::cloneExpandoChain(JSContext* cx, HandleObject dst, + HandleObject srcChain) { + MOZ_ASSERT(js::IsObjectInContextCompartment(dst, cx)); + MOZ_ASSERT(getExpandoChain(dst) == nullptr); + + RootedObject oldHead(cx, srcChain); + while (oldHead) { + // If movingIntoXrayCompartment is true, then our new reflector is in a + // compartment that used to have an Xray-with-expandos to the old reflector + // and we should copy the expandos to the new reflector directly. + bool movingIntoXrayCompartment; + + // exclusiveWrapper is only used if movingIntoXrayCompartment ends up true. + RootedObject exclusiveWrapper(cx); + RootedObject exclusiveWrapperGlobal(cx); + RootedObject wrapperHolder( + cx, + JS::GetReservedSlot(oldHead, JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER) + .toObjectOrNull()); + if (wrapperHolder) { + RootedObject unwrappedHolder(cx, UncheckedUnwrap(wrapperHolder)); + // unwrappedHolder is the compartment of the relevant Xray, so check + // whether that matches the compartment of cx (which matches the + // compartment of dst). + movingIntoXrayCompartment = + js::IsObjectInContextCompartment(unwrappedHolder, cx); + + if (!movingIntoXrayCompartment) { + // The global containing this wrapper holder has an xray for |src| + // with expandos. Create an xray in the global for |dst| which + // will be associated with a clone of |src|'s expando object. + JSAutoRealm ar(cx, unwrappedHolder); + exclusiveWrapper = dst; + if (!JS_WrapObject(cx, &exclusiveWrapper)) { + return false; + } + exclusiveWrapperGlobal = JS::CurrentGlobalOrNull(cx); + } + } else { + JSAutoRealm ar(cx, oldHead); + movingIntoXrayCompartment = + expandoObjectMatchesConsumer(cx, oldHead, GetObjectPrincipal(dst)); + } + + if (movingIntoXrayCompartment) { + // Just copy properties directly onto dst. + if (!JS_CopyOwnPropertiesAndPrivateFields(cx, dst, oldHead)) { + return false; + } + } else { + // Create a new expando object in the compartment of dst to replace + // oldHead. + RootedObject newHead( + cx, + attachExpandoObject(cx, dst, exclusiveWrapper, exclusiveWrapperGlobal, + GetExpandoObjectPrincipal(oldHead))); + if (!JS_CopyOwnPropertiesAndPrivateFields(cx, newHead, oldHead)) { + return false; + } + } + oldHead = + JS::GetReservedSlot(oldHead, JSSLOT_EXPANDO_NEXT).toObjectOrNull(); + } + return true; +} + +void ClearXrayExpandoSlots(JSObject* target, size_t slotIndex) { + if (!NS_IsMainThread()) { + // No Xrays + return; + } + + MOZ_ASSERT(slotIndex != JSSLOT_EXPANDO_NEXT); + MOZ_ASSERT(slotIndex != JSSLOT_EXPANDO_EXCLUSIVE_WRAPPER_HOLDER); + MOZ_ASSERT(GetXrayTraits(target) == &DOMXrayTraits::singleton); + RootingContext* rootingCx = RootingCx(); + RootedObject rootedTarget(rootingCx, target); + RootedObject head(rootingCx, + DOMXrayTraits::singleton.getExpandoChain(rootedTarget)); + while (head) { + MOZ_ASSERT(JSCLASS_RESERVED_SLOTS(JS::GetClass(head)) > slotIndex); + JS::SetReservedSlot(head, slotIndex, UndefinedValue()); + head = JS::GetReservedSlot(head, JSSLOT_EXPANDO_NEXT).toObjectOrNull(); + } +} + +JSObject* EnsureXrayExpandoObject(JSContext* cx, JS::HandleObject wrapper) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(GetXrayTraits(wrapper) == &DOMXrayTraits::singleton); + MOZ_ASSERT(IsXrayWrapper(wrapper)); + + RootedObject target(cx, DOMXrayTraits::getTargetObject(wrapper)); + return DOMXrayTraits::singleton.ensureExpandoObject(cx, wrapper, target); +} + +const JSClass* XrayTraits::getExpandoClass(JSContext* cx, + HandleObject target) const { + return &DefaultXrayExpandoObjectClass; +} + +static const size_t JSSLOT_XRAY_HOLDER = 0; + +/* static */ +JSObject* XrayTraits::getHolder(JSObject* wrapper) { + MOZ_ASSERT(WrapperFactory::IsXrayWrapper(wrapper)); + JS::Value v = js::GetProxyReservedSlot(wrapper, JSSLOT_XRAY_HOLDER); + return v.isObject() ? &v.toObject() : nullptr; +} + +JSObject* XrayTraits::ensureHolder(JSContext* cx, HandleObject wrapper) { + RootedObject holder(cx, getHolder(wrapper)); + if (holder) { + return holder; + } + holder = createHolder(cx, wrapper); // virtual trap. + if (holder) { + js::SetProxyReservedSlot(wrapper, JSSLOT_XRAY_HOLDER, ObjectValue(*holder)); + } + return holder; +} + +static inline JSObject* GetCachedXrayExpando(JSObject* wrapper) { + JSObject* holder = XrayTraits::getHolder(wrapper); + if (!holder) { + return nullptr; + } + Value v = JS::GetReservedSlot(holder, XrayTraits::HOLDER_SLOT_EXPANDO); + return v.isObject() ? &v.toObject() : nullptr; +} + +static inline void SetCachedXrayExpando(JSObject* holder, + JSObject* expandoWrapper) { + MOZ_ASSERT(JS::GetCompartment(holder) == JS::GetCompartment(expandoWrapper)); + JS_SetReservedSlot(holder, XrayTraits::HOLDER_SLOT_EXPANDO, + ObjectValue(*expandoWrapper)); +} + +static nsGlobalWindowInner* AsWindow(JSContext* cx, JSObject* wrapper) { + // We want to use our target object here, since we don't want to be + // doing a security check while unwrapping. + JSObject* target = XrayTraits::getTargetObject(wrapper); + return WindowOrNull(target); +} + +static bool IsWindow(JSContext* cx, JSObject* wrapper) { + return !!AsWindow(cx, wrapper); +} + +static bool wrappedJSObject_getter(JSContext* cx, unsigned argc, Value* vp) { + CallArgs args = CallArgsFromVp(argc, vp); + if (!args.thisv().isObject()) { + JS_ReportErrorASCII(cx, "This value not an object"); + return false; + } + RootedObject wrapper(cx, &args.thisv().toObject()); + if (!IsWrapper(wrapper) || !WrapperFactory::IsXrayWrapper(wrapper) || + !WrapperFactory::AllowWaiver(wrapper)) { + JS_ReportErrorASCII(cx, "Unexpected object"); + return false; + } + + args.rval().setObject(*wrapper); + + return WrapperFactory::WaiveXrayAndWrap(cx, args.rval()); +} + +bool XrayTraits::resolveOwnProperty( + JSContext* cx, HandleObject wrapper, HandleObject target, + HandleObject holder, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> desc) { + desc.reset(); + + RootedObject expando(cx); + if (!getExpandoObject(cx, target, wrapper, &expando)) { + return false; + } + + // Check for expando properties first. Note that the expando object lives + // in the target compartment. + if (expando) { + JSAutoRealm ar(cx, expando); + JS_MarkCrossZoneId(cx, id); + if (!JS_GetOwnPropertyDescriptorById(cx, expando, id, desc)) { + return false; + } + } + + // Next, check for ES builtins. + if (!desc.isSome() && JS_IsGlobalObject(target)) { + JSProtoKey key = JS_IdToProtoKey(cx, id); + JSAutoRealm ar(cx, target); + if (key != JSProto_Null) { + MOZ_ASSERT(key < JSProto_LIMIT); + RootedObject constructor(cx); + if (!JS_GetClassObject(cx, key, &constructor)) { + return false; + } + MOZ_ASSERT(constructor); + + desc.set(Some(PropertyDescriptor::Data( + ObjectValue(*constructor), + {PropertyAttribute::Configurable, PropertyAttribute::Writable}))); + } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_EVAL)) { + RootedObject eval(cx); + if (!js::GetRealmOriginalEval(cx, &eval)) { + return false; + } + desc.set(Some(PropertyDescriptor::Data( + ObjectValue(*eval), + {PropertyAttribute::Configurable, PropertyAttribute::Writable}))); + } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_INFINITY)) { + desc.set(Some(PropertyDescriptor::Data( + DoubleValue(PositiveInfinity<double>()), {}))); + } else if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_NAN)) { + desc.set(Some(PropertyDescriptor::Data(NaNValue(), {}))); + } + } + + if (desc.isSome()) { + return JS_WrapPropertyDescriptor(cx, desc); + } + + // Handle .wrappedJSObject for subsuming callers. This should move once we + // sort out own-ness for the holder. + if (id == GetJSIDByIndex(cx, XPCJSContext::IDX_WRAPPED_JSOBJECT) && + WrapperFactory::AllowWaiver(wrapper)) { + bool found = false; + if (!JS_AlreadyHasOwnPropertyById(cx, holder, id, &found)) { + return false; + } + if (!found && !JS_DefinePropertyById(cx, holder, id, wrappedJSObject_getter, + nullptr, JSPROP_ENUMERATE)) { + return false; + } + return JS_GetOwnPropertyDescriptorById(cx, holder, id, desc); + } + + return true; +} + +bool DOMXrayTraits::resolveOwnProperty( + JSContext* cx, HandleObject wrapper, HandleObject target, + HandleObject holder, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> desc) { + // Call the common code. + bool ok = + XrayTraits::resolveOwnProperty(cx, wrapper, target, holder, id, desc); + if (!ok || desc.isSome()) { + return ok; + } + + // Check for indexed access on a window. + uint32_t index = GetArrayIndexFromId(id); + if (IsArrayIndex(index)) { + nsGlobalWindowInner* win = AsWindow(cx, wrapper); + // Note: As() unwraps outer windows to get to the inner window. + if (win) { + Nullable<WindowProxyHolder> subframe = win->IndexedGetter(index); + if (!subframe.IsNull()) { + Rooted<Value> value(cx); + if (MOZ_UNLIKELY(!WrapObject(cx, subframe.Value(), &value))) { + // It's gone? + return xpc::Throw(cx, NS_ERROR_FAILURE); + } + desc.set(Some(PropertyDescriptor::Data( + value, + {PropertyAttribute::Configurable, PropertyAttribute::Enumerable}))); + return JS_WrapPropertyDescriptor(cx, desc); + } + } + } + + if (!JS_GetOwnPropertyDescriptorById(cx, holder, id, desc)) { + return false; + } + if (desc.isSome()) { + return true; + } + + bool cacheOnHolder; + if (!XrayResolveOwnProperty(cx, wrapper, target, id, desc, cacheOnHolder)) { + return false; + } + + if (desc.isNothing() || !cacheOnHolder) { + return true; + } + + Rooted<PropertyDescriptor> defineDesc(cx, *desc); + return JS_DefinePropertyById(cx, holder, id, defineDesc) && + JS_GetOwnPropertyDescriptorById(cx, holder, id, desc); +} + +bool DOMXrayTraits::delete_(JSContext* cx, JS::HandleObject wrapper, + JS::HandleId id, JS::ObjectOpResult& result) { + RootedObject target(cx, getTargetObject(wrapper)); + return XrayDeleteNamedProperty(cx, wrapper, target, id, result); +} + +bool DOMXrayTraits::defineProperty( + JSContext* cx, HandleObject wrapper, HandleId id, + Handle<PropertyDescriptor> desc, + Handle<Maybe<PropertyDescriptor>> existingDesc, + Handle<JSObject*> existingHolder, JS::ObjectOpResult& result, bool* done) { + // Check for an indexed property on a Window. If that's happening, do + // nothing but set done to true so it won't get added as an expando. + if (IsWindow(cx, wrapper)) { + if (IsArrayIndex(GetArrayIndexFromId(id))) { + *done = true; + return result.succeed(); + } + } + + JS::Rooted<JSObject*> obj(cx, getTargetObject(wrapper)); + return XrayDefineProperty(cx, wrapper, obj, id, desc, result, done); +} + +bool DOMXrayTraits::enumerateNames(JSContext* cx, HandleObject wrapper, + unsigned flags, + MutableHandleIdVector props) { + // Put the indexed properties for a window first. + nsGlobalWindowInner* win = AsWindow(cx, wrapper); + if (win) { + uint32_t length = win->Length(); + if (!props.reserve(props.length() + length)) { + return false; + } + JS::RootedId indexId(cx); + for (uint32_t i = 0; i < length; ++i) { + if (!JS_IndexToId(cx, i, &indexId)) { + return false; + } + props.infallibleAppend(indexId); + } + } + + JS::Rooted<JSObject*> obj(cx, getTargetObject(wrapper)); + if (JS_IsGlobalObject(obj)) { + // We could do this in a shared enumerateNames with JSXrayTraits, but we + // don't really have globals we expose via those. + JSAutoRealm ar(cx, obj); + if (!JS_NewEnumerateStandardClassesIncludingResolved( + cx, obj, props, !(flags & JSITER_HIDDEN))) { + return false; + } + } + return XrayOwnPropertyKeys(cx, wrapper, obj, flags, props); +} + +bool DOMXrayTraits::call(JSContext* cx, HandleObject wrapper, + const JS::CallArgs& args, + const js::Wrapper& baseInstance) { + RootedObject obj(cx, getTargetObject(wrapper)); + // What we have is either a WebIDL interface object, a WebIDL prototype + // object, or a WebIDL instance object. WebIDL interface objects we want to + // invoke on the xray compartment. WebIDL prototype objects never have a + // clasp->call. WebIDL instance objects either don't have a clasp->call or are + // using "legacycaller". At this time for all the legacycaller users it makes + // more sense to invoke on the xray compartment, so we just go ahead and do + // that for everything. + if (js::IsProxy(obj)) { + if (JS::IsCallable(obj)) { + // Passing obj here, but it doesn't really matter because legacycaller + // uses args.callee() anyway. + return GetProxyHandler(obj)->call(cx, obj, args); + } + } else { + const JSClass* clasp = JS::GetClass(obj); + if (JSNative call = clasp->getCall()) { + // call it on the Xray compartment + return call(cx, args.length(), args.base()); + } + } + + RootedValue v(cx, ObjectValue(*wrapper)); + js::ReportIsNotFunction(cx, v); + return false; +} + +bool DOMXrayTraits::construct(JSContext* cx, HandleObject wrapper, + const JS::CallArgs& args, + const js::Wrapper& baseInstance) { + RootedObject obj(cx, getTargetObject(wrapper)); + MOZ_ASSERT(mozilla::dom::HasConstructor(obj)); + const JSClass* clasp = JS::GetClass(obj); + // See comments in DOMXrayTraits::call() explaining what's going on here. + if (clasp->flags & JSCLASS_IS_DOMIFACEANDPROTOJSCLASS) { + if (JSNative construct = clasp->getConstruct()) { + if (!construct(cx, args.length(), args.base())) { + return false; + } + } else { + RootedValue v(cx, ObjectValue(*wrapper)); + js::ReportIsNotFunction(cx, v); + return false; + } + } else { + if (!baseInstance.construct(cx, wrapper, args)) { + return false; + } + } + if (!args.rval().isObject() || !JS_WrapValue(cx, args.rval())) { + return false; + } + return true; +} + +bool DOMXrayTraits::getPrototype(JSContext* cx, JS::HandleObject wrapper, + JS::HandleObject target, + JS::MutableHandleObject protop) { + return mozilla::dom::XrayGetNativeProto(cx, target, protop); +} + +void DOMXrayTraits::preserveWrapper(JSObject* target) { + nsISupports* identity = mozilla::dom::UnwrapDOMObjectToISupports(target); + if (!identity) { + return; + } + nsWrapperCache* cache = nullptr; + CallQueryInterface(identity, &cache); + if (cache) { + cache->PreserveWrapper(identity); + } +} + +JSObject* DOMXrayTraits::createHolder(JSContext* cx, JSObject* wrapper) { + return JS_NewObjectWithGivenProto(cx, &HolderClass, nullptr); +} + +const JSClass* DOMXrayTraits::getExpandoClass(JSContext* cx, + HandleObject target) const { + return XrayGetExpandoClass(cx, target); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::preventExtensions( + JSContext* cx, HandleObject wrapper, ObjectOpResult& result) const { + // Xray wrappers are supposed to provide a clean view of the target + // reflector, hiding any modifications by script in the target scope. So + // even if that script freezes the reflector, we don't want to make that + // visible to the caller. DOM reflectors are always extensible by default, + // so we can just return failure here. + return result.failCantPreventExtensions(); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::isExtensible(JSContext* cx, + JS::Handle<JSObject*> wrapper, + bool* extensible) const { + // See above. + *extensible = true; + return true; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getOwnPropertyDescriptor( + JSContext* cx, HandleObject wrapper, HandleId id, + MutableHandle<Maybe<PropertyDescriptor>> desc) const { + assertEnteredPolicy(cx, wrapper, id, + BaseProxyHandler::GET | BaseProxyHandler::SET | + BaseProxyHandler::GET_PROPERTY_DESCRIPTOR); + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject holder(cx, Traits::singleton.ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + return Traits::singleton.resolveOwnProperty(cx, wrapper, target, holder, id, + desc); +} + +// Consider what happens when chrome does |xray.expando = xray.wrappedJSObject|. +// +// Since the expando comes from the target compartment, wrapping it back into +// the target compartment to define it on the expando object ends up stripping +// off the Xray waiver that gives |xray| and |xray.wrappedJSObject| different +// identities. This is generally the right thing to do when wrapping across +// compartments, but is incorrect in the special case of the Xray expando +// object. Manually re-apply Xrays if necessary. +// +// NB: In order to satisfy the invariants of WaiveXray, we need to pass +// in an object sans security wrapper, which means we need to strip off any +// potential same-compartment security wrapper that may have been applied +// to the content object. This is ok, because the the expando object is only +// ever accessed by code across the compartment boundary. +static bool RecreateLostWaivers(JSContext* cx, const PropertyDescriptor* orig, + MutableHandle<PropertyDescriptor> wrapped) { + // Compute whether the original objects were waived, and implicitly, whether + // they were objects at all. + bool valueWasWaived = + orig->hasValue() && orig->value().isObject() && + WrapperFactory::HasWaiveXrayFlag(&orig->value().toObject()); + bool getterWasWaived = orig->hasGetter() && orig->getter() && + WrapperFactory::HasWaiveXrayFlag(orig->getter()); + bool setterWasWaived = orig->hasSetter() && orig->setter() && + WrapperFactory::HasWaiveXrayFlag(orig->setter()); + + // Recreate waivers. Note that for value, we need an extra UncheckedUnwrap + // to handle same-compartment security wrappers (see above). This should + // never happen for getters/setters. + + RootedObject rewaived(cx); + if (valueWasWaived && + !IsCrossCompartmentWrapper(&wrapped.value().toObject())) { + rewaived = &wrapped.value().toObject(); + rewaived = WrapperFactory::WaiveXray(cx, UncheckedUnwrap(rewaived)); + NS_ENSURE_TRUE(rewaived, false); + wrapped.value().set(ObjectValue(*rewaived)); + } + if (getterWasWaived && !IsCrossCompartmentWrapper(wrapped.getter())) { + // We can't end up with WindowProxy or Location as getters. + MOZ_ASSERT(CheckedUnwrapStatic(wrapped.getter())); + rewaived = WrapperFactory::WaiveXray(cx, wrapped.getter()); + NS_ENSURE_TRUE(rewaived, false); + wrapped.setGetter(rewaived); + } + if (setterWasWaived && !IsCrossCompartmentWrapper(wrapped.setter())) { + // We can't end up with WindowProxy or Location as setters. + MOZ_ASSERT(CheckedUnwrapStatic(wrapped.setter())); + rewaived = WrapperFactory::WaiveXray(cx, wrapped.setter()); + NS_ENSURE_TRUE(rewaived, false); + wrapped.setSetter(rewaived); + } + + return true; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::defineProperty(JSContext* cx, + HandleObject wrapper, + HandleId id, + Handle<PropertyDescriptor> desc, + ObjectOpResult& result) const { + assertEnteredPolicy(cx, wrapper, id, BaseProxyHandler::SET); + + Rooted<Maybe<PropertyDescriptor>> existingDesc(cx); + Rooted<JSObject*> existingHolder(cx); + if (!JS_GetPropertyDescriptorById(cx, wrapper, id, &existingDesc, + &existingHolder)) { + return false; + } + + // Note that the check here is intended to differentiate between own and + // non-own properties, since the above lookup is not limited to own + // properties. At present, this may not always do the right thing because + // we often lie (sloppily) about where we found properties and set + // existingHolder to |wrapper|. Once we fully fix our Xray prototype + // semantics, this should work as intended. + if (existingDesc.isSome() && existingHolder == wrapper && + !existingDesc->configurable()) { + // We have a non-configurable property. See if the caller is trying to + // re-configure it in any way other than making it non-writable. + if (existingDesc->isAccessorDescriptor() || desc.isAccessorDescriptor() || + (desc.hasEnumerable() && + existingDesc->enumerable() != desc.enumerable()) || + (desc.hasWritable() && !existingDesc->writable() && desc.writable())) { + // We should technically report non-configurability in strict mode, but + // doing that via JSAPI used to be a lot of trouble. See bug 1135997. + return result.succeed(); + } + if (!existingDesc->writable()) { + // Same as the above for non-writability. + return result.succeed(); + } + } + + bool done = false; + if (!Traits::singleton.defineProperty(cx, wrapper, id, desc, existingDesc, + existingHolder, result, &done)) { + return false; + } + if (done) { + return true; + } + + // Grab the relevant expando object. + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject expandoObject( + cx, Traits::singleton.ensureExpandoObject(cx, wrapper, target)); + if (!expandoObject) { + return false; + } + + // We're placing an expando. The expando objects live in the target + // compartment, so we need to enter it. + JSAutoRealm ar(cx, target); + JS_MarkCrossZoneId(cx, id); + + // Wrap the property descriptor for the target compartment. + Rooted<PropertyDescriptor> wrappedDesc(cx, desc); + if (!JS_WrapPropertyDescriptor(cx, &wrappedDesc)) { + return false; + } + + // Fix up Xray waivers. + if (!RecreateLostWaivers(cx, desc.address(), &wrappedDesc)) { + return false; + } + + return JS_DefinePropertyById(cx, expandoObject, id, wrappedDesc, result); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::ownPropertyKeys( + JSContext* cx, HandleObject wrapper, MutableHandleIdVector props) const { + assertEnteredPolicy(cx, wrapper, JS::PropertyKey::Void(), + BaseProxyHandler::ENUMERATE); + return getPropertyKeys( + cx, wrapper, JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, props); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::delete_(JSContext* cx, HandleObject wrapper, + HandleId id, + ObjectOpResult& result) const { + assertEnteredPolicy(cx, wrapper, id, BaseProxyHandler::SET); + + // Check the expando object. + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject expando(cx); + if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) { + return false; + } + + if (expando) { + JSAutoRealm ar(cx, expando); + JS_MarkCrossZoneId(cx, id); + bool hasProp; + if (!JS_HasPropertyById(cx, expando, id, &hasProp)) { + return false; + } + if (hasProp) { + return JS_DeletePropertyById(cx, expando, id, result); + } + } + + return Traits::singleton.delete_(cx, wrapper, id, result); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::get(JSContext* cx, HandleObject wrapper, + HandleValue receiver, HandleId id, + MutableHandleValue vp) const { + // This is called by Proxy::get, but since we return true for hasPrototype() + // it's only called for properties that hasOwn() claims we have as own + // properties. Since we only need to worry about own properties, we can use + // getOwnPropertyDescriptor here. + Rooted<Maybe<PropertyDescriptor>> desc(cx); + if (!getOwnPropertyDescriptor(cx, wrapper, id, &desc)) { + return false; + } + + MOZ_ASSERT(desc.isSome(), + "hasOwn() claimed we have this property, so why would we not get " + "a descriptor here?"); + desc->assertComplete(); + + // Everything after here follows [[Get]] for ordinary objects. + if (desc->isDataDescriptor()) { + vp.set(desc->value()); + return true; + } + + MOZ_ASSERT(desc->isAccessorDescriptor()); + RootedObject getter(cx, desc->getter()); + + if (!getter) { + vp.setUndefined(); + return true; + } + + return Call(cx, receiver, getter, HandleValueArray::empty(), vp); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::set(JSContext* cx, HandleObject wrapper, + HandleId id, HandleValue v, + HandleValue receiver, + ObjectOpResult& result) const { + MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()"); + return false; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::has(JSContext* cx, HandleObject wrapper, + HandleId id, bool* bp) const { + MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()"); + return false; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::hasOwn(JSContext* cx, HandleObject wrapper, + HandleId id, bool* bp) const { + // Skip our Base if it isn't already ProxyHandler. + return js::BaseProxyHandler::hasOwn(cx, wrapper, id, bp); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getOwnEnumerablePropertyKeys( + JSContext* cx, HandleObject wrapper, MutableHandleIdVector props) const { + // Skip our Base if it isn't already ProxyHandler. + return js::BaseProxyHandler::getOwnEnumerablePropertyKeys(cx, wrapper, props); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::enumerate( + JSContext* cx, HandleObject wrapper, + JS::MutableHandleIdVector props) const { + MOZ_CRASH("Shouldn't be called: we return true for hasPrototype()"); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::call(JSContext* cx, HandleObject wrapper, + const JS::CallArgs& args) const { + assertEnteredPolicy(cx, wrapper, JS::PropertyKey::Void(), + BaseProxyHandler::CALL); + // Hard cast the singleton since SecurityWrapper doesn't have one. + return Traits::call(cx, wrapper, args, Base::singleton); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::construct(JSContext* cx, HandleObject wrapper, + const JS::CallArgs& args) const { + assertEnteredPolicy(cx, wrapper, JS::PropertyKey::Void(), + BaseProxyHandler::CALL); + // Hard cast the singleton since SecurityWrapper doesn't have one. + return Traits::construct(cx, wrapper, args, Base::singleton); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getBuiltinClass(JSContext* cx, + JS::HandleObject wrapper, + js::ESClass* cls) const { + return Traits::getBuiltinClass(cx, wrapper, Base::singleton, cls); +} + +template <typename Base, typename Traits> +const char* XrayWrapper<Base, Traits>::className(JSContext* cx, + HandleObject wrapper) const { + return Traits::className(cx, wrapper, Base::singleton); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getPrototype( + JSContext* cx, JS::HandleObject wrapper, + JS::MutableHandleObject protop) const { + // We really only want this override for non-SecurityWrapper-inheriting + // |Base|. But doing that statically with templates requires partial method + // specializations (and therefore a helper class), which is all more trouble + // than it's worth. Do a dynamic check. + if (Base::hasSecurityPolicy()) { + return Base::getPrototype(cx, wrapper, protop); + } + + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject expando(cx); + if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) { + return false; + } + + // We want to keep the Xray's prototype distinct from that of content, but + // only if there's been a set. If there's not an expando, or the expando + // slot is |undefined|, hand back the default proto, appropriately wrapped. + + if (expando) { + RootedValue v(cx); + { // Scope for JSAutoRealm + JSAutoRealm ar(cx, expando); + v = JS::GetReservedSlot(expando, JSSLOT_EXPANDO_PROTOTYPE); + } + if (!v.isUndefined()) { + protop.set(v.toObjectOrNull()); + return JS_WrapObject(cx, protop); + } + } + + // Check our holder, and cache there if we don't have it cached already. + RootedObject holder(cx, Traits::singleton.ensureHolder(cx, wrapper)); + if (!holder) { + return false; + } + + Value cached = JS::GetReservedSlot(holder, Traits::HOLDER_SLOT_CACHED_PROTO); + if (cached.isUndefined()) { + if (!Traits::singleton.getPrototype(cx, wrapper, target, protop)) { + return false; + } + + JS::SetReservedSlot(holder, Traits::HOLDER_SLOT_CACHED_PROTO, + ObjectOrNullValue(protop)); + } else { + protop.set(cached.toObjectOrNull()); + } + return true; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::setPrototype(JSContext* cx, + JS::HandleObject wrapper, + JS::HandleObject proto, + JS::ObjectOpResult& result) const { + // Do this only for non-SecurityWrapper-inheriting |Base|. See the comment + // in getPrototype(). + if (Base::hasSecurityPolicy()) { + return Base::setPrototype(cx, wrapper, proto, result); + } + + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject expando( + cx, Traits::singleton.ensureExpandoObject(cx, wrapper, target)); + if (!expando) { + return false; + } + + // The expando lives in the target's realm, so do our installation there. + JSAutoRealm ar(cx, target); + + RootedValue v(cx, ObjectOrNullValue(proto)); + if (!JS_WrapValue(cx, &v)) { + return false; + } + JS_SetReservedSlot(expando, JSSLOT_EXPANDO_PROTOTYPE, v); + return result.succeed(); +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getPrototypeIfOrdinary( + JSContext* cx, JS::HandleObject wrapper, bool* isOrdinary, + JS::MutableHandleObject protop) const { + // We want to keep the Xray's prototype distinct from that of content, but + // only if there's been a set. This different-prototype-over-time behavior + // means that the [[GetPrototypeOf]] trap *can't* be ECMAScript's ordinary + // [[GetPrototypeOf]]. This also covers cross-origin Window behavior that + // per + // <https://html.spec.whatwg.org/multipage/browsers.html#windowproxy-getprototypeof> + // must be non-ordinary. + *isOrdinary = false; + return true; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::setImmutablePrototype(JSContext* cx, + JS::HandleObject wrapper, + bool* succeeded) const { + // For now, lacking an obvious place to store a bit, prohibit making an + // Xray's [[Prototype]] immutable. We can revisit this (or maybe give all + // Xrays immutable [[Prototype]], because who does this, really?) later if + // necessary. + *succeeded = false; + return true; +} + +template <typename Base, typename Traits> +bool XrayWrapper<Base, Traits>::getPropertyKeys( + JSContext* cx, HandleObject wrapper, unsigned flags, + MutableHandleIdVector props) const { + assertEnteredPolicy(cx, wrapper, JS::PropertyKey::Void(), + BaseProxyHandler::ENUMERATE); + + // Enumerate expando properties first. Note that the expando object lives + // in the target compartment. + RootedObject target(cx, Traits::getTargetObject(wrapper)); + RootedObject expando(cx); + if (!Traits::singleton.getExpandoObject(cx, target, wrapper, &expando)) { + return false; + } + + if (expando) { + JSAutoRealm ar(cx, expando); + if (!js::GetPropertyKeys(cx, expando, flags, props)) { + return false; + } + } + for (size_t i = 0; i < props.length(); ++i) { + JS_MarkCrossZoneId(cx, props[i]); + } + + return Traits::singleton.enumerateNames(cx, wrapper, flags, props); +} + +/* + * The Permissive / Security variants should be used depending on whether the + * compartment of the wrapper is guranteed to subsume the compartment of the + * wrapped object (i.e. - whether it is safe from a security perspective to + * unwrap the wrapper). + */ + +template <typename Base, typename Traits> +const xpc::XrayWrapper<Base, Traits> xpc::XrayWrapper<Base, Traits>::singleton( + 0); + +template class PermissiveXrayDOM; +template class PermissiveXrayJS; +template class PermissiveXrayOpaque; + +/* + * This callback is used by the JS engine to test if a proxy handler is for a + * cross compartment xray with no security requirements. + */ +static bool IsCrossCompartmentXrayCallback( + const js::BaseProxyHandler* handler) { + return handler == &PermissiveXrayDOM::singleton; +} + +JS::XrayJitInfo gXrayJitInfo = { + IsCrossCompartmentXrayCallback, CompartmentHasExclusiveExpandos, + JSSLOT_XRAY_HOLDER, XrayTraits::HOLDER_SLOT_EXPANDO, + JSSLOT_EXPANDO_PROTOTYPE}; + +} // namespace xpc |