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Bug 987111 - Implement resolveOwnProperty and enumerateNames for Object instances. r=gabor

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This commit is contained in:
Bobby Holley 2014-06-04 15:12:27 -07:00
parent e47ffede64
commit 5c1033b8d1
1 changed files with 153 additions and 6 deletions
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159
js/xpconnect/wrappers/XrayWrapper.cpp
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@ -18,6 +18,7 @@
#include "jsapi.h"
#include "jsprf.h"
#include "nsJSUtils.h"
#include "nsPrintfCString.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/WindowBinding.h"
@ -386,6 +387,12 @@ public:
return js::GetReservedSlot(holder, SLOT_ISPROTOTYPE).toBoolean();
}
static bool getOwnPropertyFromTargetIfSafe(JSContext *cx,
HandleObject target,
HandleObject wrapper,
HandleId id,
MutableHandle<JSPropertyDescriptor> desc);
static const JSClass HolderClass;
static JSXrayTraits singleton;
};
@ -397,6 +404,101 @@ const JSClass JSXrayTraits::HolderClass = {
JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub
};
inline bool
SilentFailure(JSContext *cx, HandleId id, const char *reason)
{
#ifdef DEBUG
nsDependentJSString name(id);
AutoFilename filename;
unsigned line = 0;
DescribeScriptedCaller(cx, &filename, &line);
NS_WARNING(nsPrintfCString("Denied access to property |%s| on Xrayed Object: %s (@%s:%u)",
NS_LossyConvertUTF16toASCII(name).get(), reason,
filename.get(), line).get());
#endif
return true;
}
bool JSXrayTraits::getOwnPropertyFromTargetIfSafe(JSContext *cx,
HandleObject target,
HandleObject wrapper,
HandleId idArg,
MutableHandle<JSPropertyDescriptor> 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(outDesc.object() == nullptr);
RootedId id(cx, idArg);
if (!JS_WrapId(cx, &id))
return false;
Rooted<JSPropertyDescriptor> desc(cx);
if (!JS_GetOwnPropertyDescriptorById(cx, target, id, &desc))
return false;
// If the property doesn't exist at all, we're done.
if (!desc.object())
return true;
// Disallow accessor properties.
if (desc.hasGetterOrSetter())
return SilentFailure(cx, id, "Property has accessor");
// Apply extra scrutiny to objects.
if (desc.value().isObject()) {
RootedObject propObj(cx, js::UncheckedUnwrap(&desc.value().toObject()));
JSAutoCompartment ac(cx, propObj);
// Disallow non-subsumed objects.
if (!AccessCheck::subsumes(target, propObj))
return SilentFailure(cx, id, "Value not same-origin with target");
// Disallow non-Xrayable objects.
if (GetXrayType(propObj) == NotXray) {
// Note - We're going add Xrays for Arrays/TypedArrays soon in
// bug 987163, so we don't want to cause unnecessary compat churn
// by making xrayedObj.arrayProp stop working temporarily, and then
// start working again. At the same time, this is an important check,
// and this patch wouldn't be as useful without it. So we just
// forcibly override the behavior here for Arrays until bug 987163
// lands.
JSProtoKey key = IdentifyStandardInstanceOrPrototype(propObj);
if (key != JSProto_Array && key != JSProto_Uint8ClampedArray &&
key != JSProto_Int8Array && key != JSProto_Uint8Array &&
key != JSProto_Int16Array && key != JSProto_Uint16Array &&
key != JSProto_Int32Array && key != JSProto_Uint32Array &&
key != JSProto_Float32Array && key != JSProto_Float64Array)
{
return SilentFailure(cx, id, "Value not Xrayable");
}
}
// Disallow callables.
if (JS_ObjectIsCallable(cx, propObj))
return SilentFailure(cx, id, "Value is callable");
}
// Disallow any property that shadows something on its (Xrayed)
// prototype chain.
JSAutoCompartment ac2(cx, wrapper);
RootedObject proto(cx);
bool foundOnProto = false;
if (!JS_GetPrototype(cx, wrapper, &proto) ||
(proto && !JS_HasPropertyById(cx, proto, id, &foundOnProto)))
{
return false;
}
if (foundOnProto)
return SilentFailure(cx, id, "Value shadows a property on the standard prototype");
// We made it! Assign over the descriptor, and don't forget to wrap.
outDesc.assign(desc.get());
return true;
}
bool
JSXrayTraits::resolveOwnProperty(JSContext *cx, Wrapper &jsWrapper,
HandleObject wrapper, HandleObject holder,
@ -409,9 +511,27 @@ JSXrayTraits::resolveOwnProperty(JSContext *cx, Wrapper &jsWrapper,
if (!ok || desc.object())
return ok;
// Non-prototypes don't have anything on them yet.
if (!isPrototype(holder))
RootedObject target(cx, getTargetObject(wrapper));
if (!isPrototype(holder)) {
// For object instances, we expose some properties from the underlying
// object, but only after filtering them carefully.
switch (getProtoKey(holder)) {
case JSProto_Object:
{
JSAutoCompartment ac(cx, target);
if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, id, desc))
return false;
}
return JS_WrapPropertyDescriptor(cx, desc);
default:
// Most instance (non-prototypes) Xrays don't have anything on them.
break;
}
// The rest of this function applies only to prototypes.
return true;
}
// The non-HasPrototypes semantics implemented by traditional Xrays are kind
// of broken with respect to |own|-ness and the holder. The common code
@ -426,7 +546,6 @@ JSXrayTraits::resolveOwnProperty(JSContext *cx, Wrapper &jsWrapper,
}
// Grab the JSClass. We require all Xrayable classes to have a ClassSpec.
RootedObject target(cx, getTargetObject(wrapper));
const js::Class *clasp = js::GetObjectClass(target);
JSProtoKey protoKey = JSCLASS_CACHED_PROTO_KEY(clasp);
MOZ_ASSERT(protoKey == getProtoKey(holder));
@ -540,16 +659,44 @@ bool
JSXrayTraits::enumerateNames(JSContext *cx, HandleObject wrapper, unsigned flags,
AutoIdVector &props)
{
RootedObject target(cx, getTargetObject(wrapper));
RootedObject holder(cx, ensureHolder(cx, wrapper));
if (!holder)
return false;
// Non-prototypes don't have anything on them yet.
if (!isPrototype(holder))
if (!isPrototype(holder)) {
// For object instances, we expose some properties from the underlying
// object, but only after filtering them carefully.
switch (getProtoKey(holder)) {
case JSProto_Object:
MOZ_ASSERT(props.empty());
{
JSAutoCompartment ac(cx, target);
AutoIdVector targetProps(cx);
if (!js::GetPropertyNames(cx, target, flags | JSITER_OWNONLY, &targetProps))
return false;
// Loop over the properties, and only pass along the ones that
// we determine to be safe.
for (size_t i = 0; i < targetProps.length(); ++i) {
Rooted<JSPropertyDescriptor> desc(cx);
RootedId id(cx, targetProps[i]);
if (!getOwnPropertyFromTargetIfSafe(cx, target, wrapper, id, &desc))
return false;
if (desc.object())
props.append(id);
}
}
return JS_WrapAutoIdVector(cx, props);
default:
// Most instance (non-prototypes) Xrays don't have anything on them.
break;
}
// The rest of this function applies only to prototypes.
return true;
}
// Grab the JSClass. We require all Xrayable classes to have a ClassSpec.
RootedObject target(cx, getTargetObject(wrapper));
const js::Class *clasp = js::GetObjectClass(target);
MOZ_ASSERT(JSCLASS_CACHED_PROTO_KEY(clasp) == getProtoKey(holder));
MOZ_ASSERT(clasp->spec.defined());