JSObject *
WrapperFactory::WrapForSameCompartment(JSContext *cx, HandleObject objArg)
{
RootedObject obj(cx, objArg);
MOZ_ASSERT(js::IsObjectInContextCompartment(obj, cx));
// NB: The contract of WrapForSameCompartment says that |obj| may or may not
// be a security wrapper. These checks implicitly handle the security
// wrapper case.
// Outerize if necessary. This, in combination with the check in
// PrepareForUnwrapping, means that calling JS_Wrap* always outerizes.
obj = JS_ObjectToOuterObject(cx, obj);
NS_ENSURE_TRUE(obj, nullptr);
if (dom::GetSameCompartmentWrapperForDOMBinding(*obj.address())) {
return obj;
}
MOZ_ASSERT(!dom::IsDOMObject(obj));
if (!IS_WN_REFLECTOR(obj))
return obj;
// Extract the WN. It should exist.
XPCWrappedNative *wn = XPCWrappedNative::Get(obj);
MOZ_ASSERT(wn, "Trying to wrap a dead WN!");
// The WN knows what to do.
RootedObject wrapper(cx, wn->GetSameCompartmentSecurityWrapper(cx));
MOZ_ASSERT_IF(wrapper != obj && IsComponentsObject(js::UncheckedUnwrap(obj)),
!Wrapper::wrapperHandler(wrapper)->isSafeToUnwrap());
return wrapper;
}
JSObject *
WrapperFactory::PrepareForWrapping(JSContext *cx, HandleObject scope,
HandleObject objArg, unsigned flags)
{
RootedObject obj(cx, objArg);
// Outerize any raw inner objects at the entry point here, so that we don't
// have to worry about them for the rest of the wrapping code.
if (js::IsInnerObject(obj)) {
JSAutoCompartment ac(cx, obj);
obj = JS_ObjectToOuterObject(cx, obj);
NS_ENSURE_TRUE(obj, nullptr);
// The outerization hook wraps, which means that we can end up with a
// CCW here if |obj| was a navigated-away-from inner. Strip any CCWs.
obj = js::UncheckedUnwrap(obj);
MOZ_ASSERT(js::IsOuterObject(obj));
}
// If we've got an outer window, there's nothing special that needs to be
// done here, and we can move on to the next phase of wrapping. We handle
// this case first to allow us to assert against wrappers below.
if (js::IsOuterObject(obj))
return DoubleWrap(cx, obj, flags);
// Here are the rules for wrapping:
// We should never get a proxy here (the JS engine unwraps those for us).
MOZ_ASSERT(!IsWrapper(obj));
// If the object being wrapped is a prototype for a standard class and the
// wrapper does not subsumes the wrappee, use the one from the content
// compartment. This is generally safer all-around, and in the COW case this
// lets us safely take advantage of things like .forEach() via the
// ChromeObjectWrapper machinery.
//
// If the prototype chain of chrome object |obj| looks like this:
//
// obj => foo => bar => chromeWin.StandardClass.prototype
//
// The prototype chain of COW(obj) looks lke this:
//
// COW(obj) => COW(foo) => COW(bar) => contentWin.StandardClass.prototype
//
// NB: We now remap all non-subsuming access of standard prototypes.
//
// NB: We need to ignore domain here so that the security relationship we
// compute here can't change over time. See the comment above the other
// subsumes call below.
bool subsumes = AccessCheck::subsumes(js::GetContextCompartment(cx),
js::GetObjectCompartment(obj));
XrayType xrayType = GetXrayType(obj);
if (!subsumes && xrayType == NotXray) {
JSProtoKey key = JSProto_Null;
{
JSAutoCompartment ac(cx, obj);
key = IdentifyStandardPrototype(obj);
}
if (key != JSProto_Null) {
RootedObject homeProto(cx);
if (!JS_GetClassPrototype(cx, key, &homeProto))
return nullptr;
MOZ_ASSERT(homeProto);
// No need to double-wrap here. We should never have waivers to
// COWs.
return homeProto;
}
}
// 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 (!IS_WN_REFLECTOR(obj) || !js::GetObjectParent(obj))
return DoubleWrap(cx, obj, flags);
XPCWrappedNative *wn = XPCWrappedNative::Get(obj);
JSAutoCompartment ac(cx, obj);
XPCCallContext ccx(JS_CALLER, cx, obj);
RootedObject wrapScope(cx, scope);
{
if (NATIVE_HAS_FLAG(&ccx, 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->GetScriptableInfo()->GetCallback()->
PreCreate(wn->Native(), cx, scope, wrapScope.address());
NS_ENSURE_SUCCESS(rv, DoubleWrap(cx, obj, flags));
// 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.
if (js::GetObjectCompartment(scope) != js::GetObjectCompartment(wrapScope))
return DoubleWrap(cx, obj, flags);
RootedObject currentScope(cx, JS_GetGlobalForObject(cx, obj));
if (MOZ_UNLIKELY(wrapScope != currentScope)) {
// The wrapper claims it wants to be in the new scope, but
// currently has a reflection that lives in the old scope. This
// can mean one of two things, both of which are rare:
//
// 1 - The object has a PreCreate hook (we checked for it above),
// but is deciding to request one-wrapper-per-scope (rather than
// one-wrapper-per-native) for some reason. Usually, a PreCreate
// hook indicates one-wrapper-per-native. In this case we want to
// make a new wrapper in the new scope.
//
// 2 - We're midway through wrapper reparenting. The document has
// moved to a new scope, but |wn| hasn't been moved yet, and
// we ended up calling JS_WrapObject() on its JS object. In this
// case, we want to return the existing wrapper.
//
// So we do a trick: call PreCreate _again_, but say that we're
// wrapping for the old scope, rather than the new one. If (1) is
// the case, then PreCreate will return the scope we pass to it
// (the old scope). If (2) is the case, PreCreate will return the
// scope of the document (the new scope).
RootedObject probe(cx);
rv = wn->GetScriptableInfo()->GetCallback()->
PreCreate(wn->Native(), cx, currentScope, probe.address());
// Check for case (2).
if (probe != currentScope) {
MOZ_ASSERT(probe == wrapScope);
return DoubleWrap(cx, obj, flags);
}
// Ok, must be case (1). Fall through and create a new wrapper.
}
// Nasty hack for late-breaking bug 781476. This will confuse identity checks,
// but it's probably better than any of our alternatives.
//
// Note: We have to ignore domain here. The JS engine assumes that, given a
// compartment c, if c->wrap(x) returns a cross-compartment wrapper at time t0,
// it will also return a cross-compartment wrapper for any time t1 > t0 unless
// an explicit transplant is performed. In particular, wrapper recomputation
// assumes that recomputing a wrapper will always result in a wrapper.
//
// This doesn't actually pose a security issue, because we'll still compute
// the correct (opaque) wrapper for the object below given the security
// characteristics of the two compartments.
if (!AccessCheck::isChrome(js::GetObjectCompartment(wrapScope)) &&
AccessCheck::subsumes(js::GetObjectCompartment(wrapScope),
js::GetObjectCompartment(obj)))
{
return DoubleWrap(cx, obj, flags);
}
}
}
// 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);
NS_ENSURE_SUCCESS(rv, nullptr);
obj.set(&v.toObject());
MOZ_ASSERT(IS_WN_REFLECTOR(obj), "bad object");
// 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);
XPCNativeSet *unionSet = XPCNativeSet::GetNewOrUsed(newwn->GetSet(),
wn->GetSet(), false);
if (!unionSet)
return nullptr;
newwn->SetSet(unionSet);
return DoubleWrap(cx, obj, flags);
}
JSObject*
WrapperFactory::PrepareForWrapping(JSContext* cx, HandleObject scope,
HandleObject objArg, HandleObject objectPassedToWrap)
{
bool waive = ShouldWaiveXray(cx, objectPassedToWrap);
RootedObject obj(cx, objArg);
// Outerize any raw inner objects at the entry point here, so that we don't
// have to worry about them for the rest of the wrapping code.
if (js::IsWindow(obj)) {
JSAutoCompartment ac(cx, obj);
obj = js::ToWindowProxyIfWindow(obj);
MOZ_ASSERT(obj);
// ToWindowProxyIfWindow can return a CCW if |obj| was a
// navigated-away-from Window. Strip any CCWs.
obj = js::UncheckedUnwrap(obj);
if (JS_IsDeadWrapper(obj)) {
JS_ReportError(cx, "Can't wrap dead object");
return nullptr;
}
MOZ_ASSERT(js::IsWindowProxy(obj));
}
// If we've got a WindowProxy, there's nothing special that needs to be
// done here, and we can move on to the next phase of wrapping. We handle
// this case first to allow us to assert against wrappers below.
if (js::IsWindowProxy(obj))
return waive ? WaiveXray(cx, obj) : obj;
// 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 (!IS_WN_REFLECTOR(obj) || JS_IsGlobalObject(obj))
return waive ? WaiveXray(cx, obj) : obj;
XPCWrappedNative* wn = XPCWrappedNative::Get(obj);
JSAutoCompartment ac(cx, obj);
XPCCallContext ccx(cx, obj);
RootedObject wrapScope(cx, scope);
{
if (NATIVE_HAS_FLAG(&ccx, 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->GetScriptableInfo()->GetCallback()->
PreCreate(wn->Native(), cx, scope, wrapScope.address());
NS_ENSURE_SUCCESS(rv, waive ? WaiveXray(cx, obj) : obj);
// 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.
if (js::GetObjectCompartment(scope) != js::GetObjectCompartment(wrapScope))
return waive ? WaiveXray(cx, obj) : obj;
RootedObject currentScope(cx, JS_GetGlobalForObject(cx, obj));
if (MOZ_UNLIKELY(wrapScope != currentScope)) {
// The wrapper claims it wants to be in the new scope, but
// currently has a reflection that lives in the old scope. This
// can mean one of two things, both of which are rare:
//
// 1 - The object has a PreCreate hook (we checked for it above),
// but is deciding to request one-wrapper-per-scope (rather than
// one-wrapper-per-native) for some reason. Usually, a PreCreate
// hook indicates one-wrapper-per-native. In this case we want to
// make a new wrapper in the new scope.
//
// 2 - We're midway through wrapper reparenting. The document has
// moved to a new scope, but |wn| hasn't been moved yet, and
// we ended up calling JS_WrapObject() on its JS object. In this
// case, we want to return the existing wrapper.
//
// So we do a trick: call PreCreate _again_, but say that we're
// wrapping for the old scope, rather than the new one. If (1) is
// the case, then PreCreate will return the scope we pass to it
// (the old scope). If (2) is the case, PreCreate will return the
// scope of the document (the new scope).
RootedObject probe(cx);
rv = wn->GetScriptableInfo()->GetCallback()->
PreCreate(wn->Native(), cx, currentScope, probe.address());
// Check for case (2).
if (probe != currentScope) {
MOZ_ASSERT(probe == wrapScope);
return waive ? WaiveXray(cx, obj) : obj;
}
// Ok, must be case (1). Fall through and create a new wrapper.
}
// Nasty hack for late-breaking bug 781476. This will confuse identity checks,
// but it's probably better than any of our alternatives.
//
// Note: We have to ignore domain here. The JS engine assumes that, given a
// compartment c, if c->wrap(x) returns a cross-compartment wrapper at time t0,
// it will also return a cross-compartment wrapper for any time t1 > t0 unless
// an explicit transplant is performed. In particular, wrapper recomputation
// assumes that recomputing a wrapper will always result in a wrapper.
//
// This doesn't actually pose a security issue, because we'll still compute
// the correct (opaque) wrapper for the object below given the security
// characteristics of the two compartments.
if (!AccessCheck::isChrome(js::GetObjectCompartment(wrapScope)) &&
AccessCheck::subsumes(js::GetObjectCompartment(wrapScope),
js::GetObjectCompartment(obj)))
{
return waive ? WaiveXray(cx, obj) : obj;
}
}
}
// 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);
NS_ENSURE_SUCCESS(rv, nullptr);
obj.set(&v.toObject());
MOZ_ASSERT(IS_WN_REFLECTOR(obj), "bad object");
// 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);
XPCNativeSet* unionSet = XPCNativeSet::GetNewOrUsed(newwn->GetSet(),
wn->GetSet(), false);
if (!unionSet)
return nullptr;
newwn->SetSet(unionSet);
return waive ? WaiveXray(cx, obj) : obj;
}