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/* -*- 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
#include "WaiveXrayWrapper.h"
#include "FilteringWrapper.h"
#include "XrayWrapper.h"
#include "AccessCheck.h"
#include "XPCWrapper.h"
#include "ChromeObjectWrapper.h"
#include "WrapperFactory.h"
#include "xpcprivate.h"
#include "XPCMaps.h"
#include "mozilla/dom/BindingUtils.h"
#include "jsfriendapi.h"
#include "js/friend/WindowProxy.h" // js::IsWindow, js::IsWindowProxy
#include "js/Object.h" // JS::GetPrivate, JS::GetCompartment
#include "mozilla/Likely.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/dom/MaybeCrossOriginObject.h"
#include "nsContentUtils.h"
#include "nsGlobalWindowInner.h"
#include "nsXULAppAPI.h"
using namespace JS;
using namespace js;
using namespace mozilla;
namespace xpc {
#ifndef MOZ_UNIFIED_BUILD
extern template class FilteringWrapper<js::CrossCompartmentSecurityWrapper,
Opaque>;
extern template class FilteringWrapper<js::CrossCompartmentSecurityWrapper,
OpaqueWithCall>;
#endif
// When chrome pulls a naked property across the membrane using
// .wrappedJSObject, we want it to cross the membrane into the
// chrome compartment without automatically being wrapped into an
// X-ray wrapper. We achieve this by wrapping it into a special
// transparent wrapper in the origin (non-chrome) compartment. When
// an object with that special wrapper applied crosses into chrome,
// we know to not apply an X-ray wrapper.
const Wrapper XrayWaiver(WrapperFactory::WAIVE_XRAY_WRAPPER_FLAG);
// When objects for which we waived the X-ray wrapper cross into
// chrome, we wrap them into a special cross-compartment wrapper
// that transitively extends the waiver to all properties we get
// off it.
const WaiveXrayWrapper WaiveXrayWrapper::singleton(0);
bool WrapperFactory::IsOpaqueWrapper(JSObject* obj) {
return IsWrapper(obj) &&
Wrapper::wrapperHandler(obj) == &PermissiveXrayOpaque::singleton;
}
bool WrapperFactory::IsCOW(JSObject* obj) {
return IsWrapper(obj) &&
Wrapper::wrapperHandler(obj) == &ChromeObjectWrapper::singleton;
}
JSObject* WrapperFactory::GetXrayWaiver(HandleObject obj) {
// Object should come fully unwrapped but outerized.
MOZ_ASSERT(obj == UncheckedUnwrap(obj));
MOZ_ASSERT(!js::IsWindow(obj));
XPCWrappedNativeScope* scope = ObjectScope(obj);
MOZ_ASSERT(scope);
if (!scope->mWaiverWrapperMap) {
return nullptr;
}
return scope->mWaiverWrapperMap->Find(obj);
}
JSObject* WrapperFactory::CreateXrayWaiver(JSContext* cx, HandleObject obj,
bool allowExisting) {
// The caller is required to have already done a lookup, unless it's
// trying to replace an existing waiver.
// NB: This implictly performs the assertions of GetXrayWaiver.
MOZ_ASSERT(bool(GetXrayWaiver(obj)) == allowExisting);
XPCWrappedNativeScope* scope = ObjectScope(obj);
JSAutoRealm ar(cx, obj);
JSObject* waiver = Wrapper::New(cx, obj, &XrayWaiver);
if (!waiver) {
return nullptr;
}
// Add the new waiver to the map. It's important that we only ever have
// one waiver for the lifetime of the target object.
if (!scope->mWaiverWrapperMap) {
scope->mWaiverWrapperMap = mozilla::MakeUnique<JSObject2JSObjectMap>();
}
if (!scope->mWaiverWrapperMap->Add(cx, obj, waiver)) {
return nullptr;
}
return waiver;
}
JSObject* WrapperFactory::WaiveXray(JSContext* cx, JSObject* objArg) {
RootedObject obj(cx, objArg);
obj = UncheckedUnwrap(obj);
MOZ_ASSERT(!js::IsWindow(obj));
JSObject* waiver = GetXrayWaiver(obj);
if (!waiver) {
waiver = CreateXrayWaiver(cx, obj);
}
JS::AssertObjectIsNotGray(waiver);
return waiver;
}
/* static */
bool WrapperFactory::AllowWaiver(JS::Compartment* target,
JS::Compartment* origin) {
return CompartmentPrivate::Get(target)->allowWaivers &&
CompartmentOriginInfo::Subsumes(target, origin);
}
/* static */
bool WrapperFactory::AllowWaiver(JSObject* wrapper) {
MOZ_ASSERT(js::IsCrossCompartmentWrapper(wrapper));
return AllowWaiver(JS::GetCompartment(wrapper),
JS::GetCompartment(js::UncheckedUnwrap(wrapper)));
}
inline bool ShouldWaiveXray(JSContext* cx, JSObject* originalObj) {
unsigned flags;
(void)js::UncheckedUnwrap(originalObj, /* stopAtWindowProxy = */ true,
&flags);
// If the original object did not point through an Xray waiver, we're done.
if (!(flags & WrapperFactory::WAIVE_XRAY_WRAPPER_FLAG)) {
return false;
}
// If the original object was not a cross-compartment wrapper, that means
// that the caller explicitly created a waiver. Preserve it so that things
// like WaiveXrayAndWrap work.
if (!(flags & Wrapper::CROSS_COMPARTMENT)) {
return true;
}
// Otherwise, this is a case of explicitly passing a wrapper across a
// compartment boundary. In that case, we only want to preserve waivers
// in transactions between same-origin compartments.
JS::Compartment* oldCompartment = JS::GetCompartment(originalObj);
JS::Compartment* newCompartment = js::GetContextCompartment(cx);
bool sameOrigin = false;
if (OriginAttributes::IsRestrictOpenerAccessForFPI()) {
sameOrigin =
CompartmentOriginInfo::Subsumes(oldCompartment, newCompartment) &&
CompartmentOriginInfo::Subsumes(newCompartment, oldCompartment);
} else {
sameOrigin = CompartmentOriginInfo::SubsumesIgnoringFPD(oldCompartment,
newCompartment) &&
CompartmentOriginInfo::SubsumesIgnoringFPD(newCompartment,
oldCompartment);
}
return sameOrigin;
}
// Special handling is needed when wrapping local and remote window proxies.
// This function returns true if it found a window proxy and dealt with it.
static bool MaybeWrapWindowProxy(JSContext* cx, HandleObject origObj,
HandleObject obj, MutableHandleObject retObj) {
bool isWindowProxy = js::IsWindowProxy(obj);
if (!isWindowProxy &&
!dom::IsRemoteObjectProxy(obj, dom::prototypes::id::Window)) {
return false;
}
dom::BrowsingContext* bc = nullptr;
if (isWindowProxy) {
nsGlobalWindowInner* win =
WindowOrNull(js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false));
if (win && win->GetOuterWindow()) {
bc = win->GetOuterWindow()->GetBrowsingContext();
}
if (!bc) {
retObj.set(obj);
return true;
}
} else {
bc = dom::GetBrowsingContext(obj);
MOZ_ASSERT(bc);
}
// We should only have a remote window proxy if bc is in a state where we
// expect remote window proxies. Otherwise, they should have been cleaned up
// by a call to CleanUpDanglingRemoteOuterWindowProxies().
MOZ_RELEASE_ASSERT(isWindowProxy || bc->CanHaveRemoteOuterProxies());
if (bc->IsInProcess()) {
retObj.set(obj);
} else {
// If bc is not in process, then use a remote window proxy, whether or not
// obj is one already.
if (!dom::GetRemoteOuterWindowProxy(cx, bc, origObj, retObj)) {
MOZ_CRASH("GetRemoteOuterWindowProxy failed");
}
}
return true;
}
void WrapperFactory::PrepareForWrapping(JSContext* cx, HandleObject scope,
HandleObject origObj,
HandleObject objArg,
HandleObject objectPassedToWrap,
MutableHandleObject retObj) {
// The JS engine calls ToWindowProxyIfWindow and deals with dead wrappers.
MOZ_ASSERT(!js::IsWindow(objArg));
MOZ_ASSERT(!JS_IsDeadWrapper(objArg));
bool waive = ShouldWaiveXray(cx, objectPassedToWrap);
RootedObject obj(cx, objArg);
retObj.set(nullptr);
// There are a few cases related to window proxies that are handled first to
// allow us to assert against wrappers below.
if (MaybeWrapWindowProxy(cx, origObj, obj, retObj)) {
if (waive) {
// We don't put remote window proxies in a waiving wrapper.
MOZ_ASSERT(js::IsWindowProxy(obj));
retObj.set(WaiveXray(cx, retObj));
}
return;
}
// Here are the rules for wrapping:
// We should never get a proxy here (the JS engine unwraps those for us).
MOZ_ASSERT(!IsWrapper(obj));
// Now, our object is ready to be wrapped, but several objects (notably
// nsJSIIDs) have a wrapper per scope. If we are about to wrap one of
// those objects in a security wrapper, then we need to hand back the
// wrapper for the new scope instead. Also, global objects don't move
// between scopes so for those we also want to return the wrapper. So...
if (!IsWrappedNativeReflector(obj) || JS_IsGlobalObject(obj)) {
retObj.set(waive ? WaiveXray(cx, obj) : obj);
return;
}
XPCWrappedNative* wn = XPCWrappedNative::Get(obj);
JSAutoRealm ar(cx, obj);
XPCCallContext ccx(cx, obj);
RootedObject wrapScope(cx, scope);
if (ccx.GetScriptable() && ccx.GetScriptable()->WantPreCreate()) {
// We have a precreate hook. This object might enforce that we only
// ever create JS object for it.
// Note: this penalizes objects that only have one wrapper, but are
// being accessed across compartments. We would really prefer to
// replace the above code with a test that says "do you only have one
// wrapper?"
nsresult rv = wn->GetScriptable()->PreCreate(wn->Native(), cx, scope,
wrapScope.address());
if (NS_FAILED(rv)) {
retObj.set(waive ? WaiveXray(cx, obj) : obj);
return;
}
// If the handed back scope differs from the passed-in scope and is in
// a separate compartment, then this object is explicitly requesting
// that we don't create a second JS object for it: create a security
// wrapper.
//
// Note: The only two objects that still use PreCreate are BackstagePass
// and Components, both of which unconditionally request their canonical
// scope. Since SpiderMonkey only invokes the prewrap callback in
// situations where the object is nominally cross-compartment, we should
// always get a different scope here.
MOZ_RELEASE_ASSERT(JS::GetCompartment(scope) !=
JS::GetCompartment(wrapScope));
retObj.set(waive ? WaiveXray(cx, obj) : obj);
return;
}
// This public WrapNativeToJSVal API enters the compartment of 'wrapScope'
// so we don't have to.
RootedValue v(cx);
nsresult rv = nsXPConnect::XPConnect()->WrapNativeToJSVal(
cx, wrapScope, wn->Native(), nullptr, &NS_GET_IID(nsISupports), false,
&v);
if (NS_FAILED(rv)) {
return;
}
obj.set(&v.toObject());
MOZ_ASSERT(IsWrappedNativeReflector(obj), "bad object");
JS::AssertObjectIsNotGray(obj); // We should never return gray reflectors.
// Because the underlying native didn't have a PreCreate hook, we had
// to a new (or possibly pre-existing) XPCWN in our compartment.
// This could be a problem for chrome code that passes XPCOM objects
// across compartments, because the effects of QI would disappear across
// compartments.
//
// So whenever we pull an XPCWN across compartments in this manner, we
// give the destination object the union of the two native sets. We try
// to do this cleverly in the common case to avoid too much overhead.
XPCWrappedNative* newwn = XPCWrappedNative::Get(obj);
RefPtr<XPCNativeSet> unionSet =
XPCNativeSet::GetNewOrUsed(cx, newwn->GetSet(), wn->GetSet(), false);
if (!unionSet) {
return;
}
newwn->SetSet(unionSet.forget());
retObj.set(waive ? WaiveXray(cx, obj) : obj);
}
// This check is completely symmetric, so we don't need to keep track of origin
// vs target here. Two compartments may have had transparent CCWs between them
// only if they are same-origin (ignoring document.domain) or have both had
// document.domain set at some point and are same-site. In either case they
// will have the same SiteIdentifier, so check that first.
static bool CompartmentsMayHaveHadTransparentCCWs(
CompartmentPrivate* private1, CompartmentPrivate* private2) {
auto& info1 = private1->originInfo;
auto& info2 = private2->originInfo;
if (!info1.SiteRef().Equals(info2.SiteRef())) {
return false;
}
return info1.GetPrincipalIgnoringDocumentDomain()->FastEquals(
info2.GetPrincipalIgnoringDocumentDomain()) ||
(info1.HasChangedDocumentDomain() && info2.HasChangedDocumentDomain());
}
#ifdef DEBUG
static void DEBUG_CheckUnwrapSafety(HandleObject obj,
const js::Wrapper* handler,
JS::Realm* origin, JS::Realm* target) {
JS::Compartment* targetCompartment = JS::GetCompartmentForRealm(target);
if (!js::AllowNewWrapper(targetCompartment, obj)) {
// The JS engine should have returned a dead wrapper in this case and we
// shouldn't even get here.
MOZ_ASSERT_UNREACHABLE("CheckUnwrapSafety called for a dead wrapper");
} else if (AccessCheck::isChrome(targetCompartment)) {
// If the caller is chrome (or effectively so), unwrap should always be
// allowed, but we might have a CrossOriginObjectWrapper here which allows
// it dynamically.
MOZ_ASSERT(!handler->hasSecurityPolicy() ||
handler == &CrossOriginObjectWrapper::singleton);
} else {
// Otherwise, it should depend on whether the target subsumes the origin.
bool subsumes =
(OriginAttributes::IsRestrictOpenerAccessForFPI()
? AccessCheck::subsumesConsideringDomain(target, origin)
: AccessCheck::subsumesConsideringDomainIgnoringFPD(target,
origin));
if (!subsumes) {
// If the target (which is where the wrapper lives) does not subsume the
// origin (which is where the wrapped object lives), then we should
// generally have a security check on the wrapper here. There is one
// exception, though: things that used to be same-origin and then stopped
// due to document.domain changes. In that case we will have a
// transparent cross-compartment wrapper here even though "subsumes" is no
// longer true.
CompartmentPrivate* originCompartmentPrivate =
CompartmentPrivate::Get(origin);
CompartmentPrivate* targetCompartmentPrivate =
CompartmentPrivate::Get(target);
if (!originCompartmentPrivate->wantXrays &&
!targetCompartmentPrivate->wantXrays &&
CompartmentsMayHaveHadTransparentCCWs(originCompartmentPrivate,
targetCompartmentPrivate)) {
// We should have a transparent CCW, unless we have a cross-origin
// object, in which case it will be a CrossOriginObjectWrapper.
MOZ_ASSERT(handler == &CrossCompartmentWrapper::singleton ||
handler == &CrossOriginObjectWrapper::singleton);
} else {
MOZ_ASSERT(handler->hasSecurityPolicy());
}
} else {
// Even if target subsumes origin, we might have a wrapper with a security
// policy here, if it happens to be a CrossOriginObjectWrapper.
MOZ_ASSERT(!handler->hasSecurityPolicy() ||
handler == &CrossOriginObjectWrapper::singleton);
}
}
}
#else
# define DEBUG_CheckUnwrapSafety(obj, handler, origin, target) \
{}
#endif
const CrossOriginObjectWrapper CrossOriginObjectWrapper::singleton;
bool CrossOriginObjectWrapper::dynamicCheckedUnwrapAllowed(
HandleObject obj, JSContext* cx) const {
MOZ_ASSERT(js::GetProxyHandler(obj) == this,
"Why are we getting called for some random object?");
JSObject* target = wrappedObject(obj);
return dom::MaybeCrossOriginObjectMixins::IsPlatformObjectSameOrigin(cx,
target);
}
static const Wrapper* SelectWrapper(bool securityWrapper, XrayType xrayType,
bool waiveXrays, JSObject* obj) {
// Waived Xray uses a modified CCW that has transparent behavior but
// transitively waives Xrays on arguments.
if (waiveXrays) {
MOZ_ASSERT(!securityWrapper);
return &WaiveXrayWrapper::singleton;
}
// If we don't want or can't use Xrays, select a wrapper that's either
// entirely transparent or entirely opaque.
if (xrayType == NotXray) {
if (!securityWrapper) {
return &CrossCompartmentWrapper::singleton;
}
return &FilteringWrapper<CrossCompartmentSecurityWrapper,
Opaque>::singleton;
}
// Ok, we're using Xray. If this isn't a security wrapper, use the permissive
// version and skip the filter.
if (!securityWrapper) {
if (xrayType == XrayForDOMObject) {
return &PermissiveXrayDOM::singleton;
} else if (xrayType == XrayForJSObject) {
return &PermissiveXrayJS::singleton;
}
MOZ_ASSERT(xrayType == XrayForOpaqueObject);
return &PermissiveXrayOpaque::singleton;
}
// There's never any reason to expose other objects to non-subsuming actors.
// Just use an opaque wrapper in these cases.
return &FilteringWrapper<CrossCompartmentSecurityWrapper, Opaque>::singleton;
}
JSObject* WrapperFactory::Rewrap(JSContext* cx, HandleObject existing,
HandleObject obj) {
MOZ_ASSERT(!IsWrapper(obj) || GetProxyHandler(obj) == &XrayWaiver ||
js::IsWindowProxy(obj),
"wrapped object passed to rewrap");
MOZ_ASSERT(!js::IsWindow(obj));
MOZ_ASSERT(dom::IsJSAPIActive());
// Compute the information we need to select the right wrapper.
JS::Realm* origin = js::GetNonCCWObjectRealm(obj);
JS::Realm* target = js::GetContextRealm(cx);
MOZ_ASSERT(target, "Why is our JSContext not in a Realm?");
bool originIsChrome = AccessCheck::isChrome(origin);
bool targetIsChrome = AccessCheck::isChrome(target);
bool originSubsumesTarget =
OriginAttributes::IsRestrictOpenerAccessForFPI()
? AccessCheck::subsumesConsideringDomain(origin, target)
: AccessCheck::subsumesConsideringDomainIgnoringFPD(origin, target);
bool targetSubsumesOrigin =
OriginAttributes::IsRestrictOpenerAccessForFPI()
? AccessCheck::subsumesConsideringDomain(target, origin)
: AccessCheck::subsumesConsideringDomainIgnoringFPD(target, origin);
bool sameOrigin = targetSubsumesOrigin && originSubsumesTarget;
const Wrapper* wrapper;
CompartmentPrivate* originCompartmentPrivate =
CompartmentPrivate::Get(origin);
CompartmentPrivate* targetCompartmentPrivate =
CompartmentPrivate::Get(target);
// Track whether we decided to use a transparent wrapper because of
// document.domain usage, so we don't override that decision.
bool isTransparentWrapperDueToDocumentDomain = false;
//
// First, handle the special cases.
//
// Special handling for chrome objects being exposed to content.
if (originIsChrome && !targetIsChrome) {
// If this is a chrome function being exposed to content, we need to allow
// call (but nothing else).
JSProtoKey key = IdentifyStandardInstance(obj);
if (key == JSProto_Function || key == JSProto_BoundFunction) {
wrapper = &FilteringWrapper<CrossCompartmentSecurityWrapper,
OpaqueWithCall>::singleton;
}
// For vanilla JSObjects exposed from chrome to content, we use a wrapper
// that fails silently in a few cases. We'd like to get rid of this
// eventually, but in their current form they don't cause much trouble.
else if (key == JSProto_Object) {
wrapper = &ChromeObjectWrapper::singleton;
}
// Otherwise we get an opaque wrapper.
else {
wrapper =
&FilteringWrapper<CrossCompartmentSecurityWrapper, Opaque>::singleton;
}
}
// Special handling for the web's cross-origin objects (WindowProxy and
// Location). We only need or want to do this in web-like contexts, where all
// security relationships are symmetric and there are no forced Xrays.
else if (originSubsumesTarget == targetSubsumesOrigin &&
// Check for the more rare case of cross-origin objects before doing
// the more-likely-to-pass checks for wantXrays.
IsCrossOriginAccessibleObject(obj) &&
(!targetSubsumesOrigin || (!originCompartmentPrivate->wantXrays &&
!targetCompartmentPrivate->wantXrays))) {
wrapper = &CrossOriginObjectWrapper::singleton;
}
// Special handling for other web objects. Again, we only want this in
// web-like contexts (symmetric security relationships, no forced Xrays). In
// this situation, if the two compartments may ever have had transparent CCWs
// between them, we want to keep using transparent CCWs.
else if (originSubsumesTarget == targetSubsumesOrigin &&
!originCompartmentPrivate->wantXrays &&
!targetCompartmentPrivate->wantXrays &&
CompartmentsMayHaveHadTransparentCCWs(originCompartmentPrivate,
targetCompartmentPrivate)) {
isTransparentWrapperDueToDocumentDomain = true;
wrapper = &CrossCompartmentWrapper::singleton;
}
//
// Now, handle the regular cases.
//
// These are wrappers we can compute using a rule-based approach. In order
// to do so, we need to compute some parameters.
//
else {
// The wrapper is a security wrapper (protecting the wrappee) if and
// only if the target does not subsume the origin.
bool securityWrapper = !targetSubsumesOrigin;
// Xrays are warranted if either the target or the origin don't trust
// each other. This is generally the case, unless the two are same-origin
// and the caller has not requested same-origin Xrays.
//
// Xrays are a bidirectional protection, since it affords clarity to the
// caller and privacy to the callee.
bool sameOriginXrays = originCompartmentPrivate->wantXrays ||
targetCompartmentPrivate->wantXrays;
bool wantXrays = !sameOrigin || sameOriginXrays;
XrayType xrayType = wantXrays ? GetXrayType(obj) : NotXray;
// If Xrays are warranted, the caller may waive them for non-security
// wrappers (unless explicitly forbidden from doing so).
bool waiveXrays = wantXrays && !securityWrapper &&
targetCompartmentPrivate->allowWaivers &&
HasWaiveXrayFlag(obj);
wrapper = SelectWrapper(securityWrapper, xrayType, waiveXrays, obj);
}
if (!targetSubsumesOrigin && !isTransparentWrapperDueToDocumentDomain) {
// Do a belt-and-suspenders check against exposing eval()/Function() to
// non-subsuming content.
if (JSFunction* fun = JS_GetObjectFunction(obj)) {
if (JS_IsBuiltinEvalFunction(fun) ||
JS_IsBuiltinFunctionConstructor(fun)) {
NS_WARNING(
"Trying to expose eval or Function to non-subsuming content!");
wrapper = &FilteringWrapper<CrossCompartmentSecurityWrapper,
Opaque>::singleton;
}
}
}
DEBUG_CheckUnwrapSafety(obj, wrapper, origin, target);
if (existing) {
return Wrapper::Renew(existing, obj, wrapper);
}
return Wrapper::New(cx, obj, wrapper);
}
// Call WaiveXrayAndWrap when you have a JS object that you don't want to be
// wrapped in an Xray wrapper. cx->compartment is the compartment that will be
// using the returned object. If the object to be wrapped is already in the
// correct compartment, then this returns the unwrapped object.
bool WrapperFactory::WaiveXrayAndWrap(JSContext* cx, MutableHandleValue vp) {
if (vp.isPrimitive()) {
return JS_WrapValue(cx, vp);
}
RootedObject obj(cx, &vp.toObject());
if (!WaiveXrayAndWrap(cx, &obj)) {
return false;
}
vp.setObject(*obj);
return true;
}
bool WrapperFactory::WaiveXrayAndWrap(JSContext* cx,
MutableHandleObject argObj) {
MOZ_ASSERT(argObj);
RootedObject obj(cx, js::UncheckedUnwrap(argObj));
MOZ_ASSERT(!js::IsWindow(obj));
if (js::IsObjectInContextCompartment(obj, cx)) {
argObj.set(obj);
return true;
}
// Even though waivers have no effect on access by scopes that don't subsume
// the underlying object, good defense-in-depth dictates that we should avoid
// handing out waivers to callers that can't use them. The transitive waiving
// machinery unconditionally calls WaiveXrayAndWrap on return values from
// waived functions, even though the return value might be not be same-origin
// with the function. So if we find ourselves trying to create a waiver for
// |cx|, we should check whether the caller has any business with waivers
// to things in |obj|'s compartment.
JS::Compartment* target = js::GetContextCompartment(cx);
JS::Compartment* origin = JS::GetCompartment(obj);
obj = AllowWaiver(target, origin) ? WaiveXray(cx, obj) : obj;
if (!obj) {
return false;
}
if (!JS_WrapObject(cx, &obj)) {
return false;
}
argObj.set(obj);
return true;
}
/*
* Calls to JS_TransplantObject* should go through these helpers here so that
* waivers get fixed up properly.
*/
static bool FixWaiverAfterTransplant(JSContext* cx, HandleObject oldWaiver,
HandleObject newobj,
bool crossCompartmentTransplant) {
MOZ_ASSERT(Wrapper::wrapperHandler(oldWaiver) == &XrayWaiver);
MOZ_ASSERT(!js::IsCrossCompartmentWrapper(newobj));
if (crossCompartmentTransplant) {
// If the new compartment has a CCW for oldWaiver, nuke this CCW. This
// prevents confusing RemapAllWrappersForObject: it would call RemapWrapper
// with two same-compartment objects (the CCW and the new waiver).
//
// This can happen when loading a chrome page in a content frame and there
// exists a CCW from the chrome compartment to oldWaiver wrapping the window
// we just transplanted:
//
// Compartment 1 | Compartment 2
// ----------------------------------------
// CCW1 -----------> oldWaiver --> CCW2 --+
// newWaiver |
// WindowProxy <--------------------------+
js::NukeCrossCompartmentWrapperIfExists(cx, JS::GetCompartment(newobj),
oldWaiver);
} else {
// We kept the same object identity, so the waiver should be a
// waiver for our object, just in the wrong Realm.
MOZ_ASSERT(newobj == Wrapper::wrappedObject(oldWaiver));
}
// Create a waiver in the new compartment. We know there's not one already in
// the crossCompartmentTransplant case because we _just_ transplanted, which
// means that |newobj| was either created from scratch, or was previously
// cross-compartment wrapper (which should have no waiver). On the other hand,
// in the !crossCompartmentTransplant case we know one already exists.
// CreateXrayWaiver asserts all this.
RootedObject newWaiver(
cx, WrapperFactory::CreateXrayWaiver(
cx, newobj, /* allowExisting = */ !crossCompartmentTransplant));
if (!newWaiver) {
return false;
}
if (!crossCompartmentTransplant) {
// CreateXrayWaiver should have updated the map to point to the new waiver.
MOZ_ASSERT(WrapperFactory::GetXrayWaiver(newobj) == newWaiver);
}
// Update all the cross-compartment references to oldWaiver to point to
// newWaiver.
if (!js::RemapAllWrappersForObject(cx, oldWaiver, newWaiver)) {
return false;
}
if (crossCompartmentTransplant) {
// There should be no same-compartment references to oldWaiver, and we
// just remapped all cross-compartment references. It's dead, so we can
// remove it from the map.
XPCWrappedNativeScope* scope = ObjectScope(oldWaiver);
JSObject* key = Wrapper::wrappedObject(oldWaiver);
MOZ_ASSERT(scope->mWaiverWrapperMap->Find(key));
scope->mWaiverWrapperMap->Remove(key);
}
return true;
}
JSObject* TransplantObject(JSContext* cx, JS::HandleObject origobj,
JS::HandleObject target) {
RootedObject oldWaiver(cx, WrapperFactory::GetXrayWaiver(origobj));
MOZ_ASSERT_IF(oldWaiver, GetNonCCWObjectRealm(oldWaiver) ==
GetNonCCWObjectRealm(origobj));
RootedObject newIdentity(cx, JS_TransplantObject(cx, origobj, target));
if (!newIdentity || !oldWaiver) {
return newIdentity;
}
bool crossCompartmentTransplant = (newIdentity != origobj);
if (!crossCompartmentTransplant) {
// We might still have been transplanted across realms within a single
// compartment.
if (GetNonCCWObjectRealm(oldWaiver) == GetNonCCWObjectRealm(newIdentity)) {
// The old waiver is same-realm with the new object; nothing else to do
// here.
return newIdentity;
}
}
if (!FixWaiverAfterTransplant(cx, oldWaiver, newIdentity,
crossCompartmentTransplant)) {
return nullptr;
}
return newIdentity;
}
JSObject* TransplantObjectRetainingXrayExpandos(JSContext* cx,
JS::HandleObject origobj,
JS::HandleObject target) {
// Save the chain of objects that carry origobj's Xray expando properties
// (from all compartments). TransplantObject will blow this away; we'll
// restore it manually afterwards.
RootedObject expandoChain(
cx, GetXrayTraits(origobj)->detachExpandoChain(origobj));
RootedObject newIdentity(cx, TransplantObject(cx, origobj, target));
// Copy Xray expando properties to the new wrapper.
if (!GetXrayTraits(newIdentity)
->cloneExpandoChain(cx, newIdentity, expandoChain)) {
// Failure here means some expandos were not copied over. The object graph
// and the Xray machinery are left in a consistent state, but mysteriously
// losing these expandos is too weird to allow.
MOZ_CRASH();
}
return newIdentity;
}
static void NukeXrayWaiver(JSContext* cx, JS::HandleObject obj) {
RootedObject waiver(cx, WrapperFactory::GetXrayWaiver(obj));
if (!waiver) {
return;
}
XPCWrappedNativeScope* scope = ObjectScope(waiver);
JSObject* key = Wrapper::wrappedObject(waiver);
MOZ_ASSERT(scope->mWaiverWrapperMap->Find(key));
scope->mWaiverWrapperMap->Remove(key);
js::NukeNonCCWProxy(cx, waiver);
// Get rid of any CCWs the waiver may have had.
if (!JS_RefreshCrossCompartmentWrappers(cx, waiver)) {
MOZ_CRASH();
}
}
JSObject* TransplantObjectNukingXrayWaiver(JSContext* cx,
JS::HandleObject origObj,
JS::HandleObject target) {
NukeXrayWaiver(cx, origObj);
return JS_TransplantObject(cx, origObj, target);
}
nsIGlobalObject* NativeGlobal(JSObject* obj) {
obj = JS::GetNonCCWObjectGlobal(obj);
// Every global needs to hold a native as its first reserved slot or be a
// WebIDL object with an nsISupports DOM object.
MOZ_ASSERT(JS::GetClass(obj)->slot0IsISupports() ||
dom::UnwrapDOMObjectToISupports(obj));
nsISupports* native = dom::UnwrapDOMObjectToISupports(obj);
if (!native) {
native = JS::GetObjectISupports<nsISupports>(obj);
MOZ_ASSERT(native);
// In some cases (like for windows) it is a wrapped native,
// in other cases (sandboxes, backstage passes) it's just
// a direct pointer to the native. If it's a wrapped native
// let's unwrap it first.
if (nsCOMPtr<nsIXPConnectWrappedNative> wn = do_QueryInterface(native)) {
native = wn->Native();
}
}
nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(native);
MOZ_ASSERT(global,
"Native held by global needs to implement nsIGlobalObject!");
return global;
}
nsIGlobalObject* CurrentNativeGlobal(JSContext* cx) {
return xpc::NativeGlobal(JS::CurrentGlobalOrNull(cx));
}
} // namespace xpc