bool
ExposedPropertiesOnly::check(JSContext* cx, HandleObject wrapper, HandleId id, Wrapper::Action act)
{
RootedObject wrappedObject(cx, Wrapper::wrappedObject(wrapper));
if (act == Wrapper::CALL)
return false;
// For the case of getting a property descriptor, we allow if either GET or SET
// is allowed, and rely on FilteringWrapper to filter out any disallowed accessors.
if (act == Wrapper::GET_PROPERTY_DESCRIPTOR) {
return check(cx, wrapper, id, Wrapper::GET) ||
check(cx, wrapper, id, Wrapper::SET);
}
RootedId exposedPropsId(cx, GetRTIdByIndex(cx, XPCJSRuntime::IDX_EXPOSEDPROPS));
// We need to enter the wrappee's compartment to look at __exposedProps__,
// but we want to be in the wrapper's compartment if we call Deny().
//
// Unfortunately, |cx| can be in either compartment when we call ::check. :-(
JSAutoCompartment ac(cx, wrappedObject);
bool found = false;
if (!JS_HasPropertyById(cx, wrappedObject, exposedPropsId, &found))
return false;
// If no __exposedProps__ existed, deny access.
if (!found) {
// Previously we automatically granted access to indexed properties and
// .length for Array COWs. We're not doing that anymore, so make sure to
// let people know what's going on.
bool isArray;
if (!JS_IsArrayObject(cx, wrappedObject, &isArray))
return false;
if (!isArray)
isArray = JS_IsTypedArrayObject(wrappedObject);
bool isIndexedAccessOnArray = isArray && JSID_IS_INT(id) && JSID_TO_INT(id) >= 0;
bool isLengthAccessOnArray = isArray && JSID_IS_STRING(id) &&
JS_FlatStringEqualsAscii(JSID_TO_FLAT_STRING(id), "length");
if (isIndexedAccessOnArray || isLengthAccessOnArray) {
JSAutoCompartment ac2(cx, wrapper);
ReportWrapperDenial(cx, id, WrapperDenialForCOW,
"Access to elements and length of privileged Array not permitted");
}
return false;
}
if (id == JSID_VOID)
return true;
Rooted<JSPropertyDescriptor> desc(cx);
if (!JS_GetPropertyDescriptorById(cx, wrappedObject, exposedPropsId, &desc))
return false;
if (!desc.object())
return false;
if (desc.hasGetterOrSetter()) {
EnterAndThrow(cx, wrapper, "__exposedProps__ must be a value property");
return false;
}
RootedValue exposedProps(cx, desc.value());
if (exposedProps.isNullOrUndefined())
return false;
if (!exposedProps.isObject()) {
EnterAndThrow(cx, wrapper, "__exposedProps__ must be undefined, null, or an Object");
return false;
}
RootedObject hallpass(cx, &exposedProps.toObject());
if (!AccessCheck::subsumes(js::UncheckedUnwrap(hallpass), wrappedObject)) {
EnterAndThrow(cx, wrapper, "Invalid __exposedProps__");
return false;
}
Access access = NO_ACCESS;
if (!JS_GetPropertyDescriptorById(cx, hallpass, id, &desc)) {
return false; // Error
}
if (!desc.object() || !desc.enumerable())
return false;
if (!desc.value().isString()) {
EnterAndThrow(cx, wrapper, "property must be a string");
return false;
}
JSFlatString* flat = JS_FlattenString(cx, desc.value().toString());
if (!flat)
return false;
size_t length = JS_GetStringLength(JS_FORGET_STRING_FLATNESS(flat));
for (size_t i = 0; i < length; ++i) {
char16_t ch = JS_GetFlatStringCharAt(flat, i);
switch (ch) {
case 'r':
if (access & READ) {
EnterAndThrow(cx, wrapper, "duplicate 'readable' property flag");
return false;
}
access = Access(access | READ);
break;
case 'w':
if (access & WRITE) {
EnterAndThrow(cx, wrapper, "duplicate 'writable' property flag");
return false;
}
access = Access(access | WRITE);
break;
default:
EnterAndThrow(cx, wrapper, "properties can only be readable or read and writable");
return false;
}
}
if (access == NO_ACCESS) {
EnterAndThrow(cx, wrapper, "specified properties must have a permission bit set");
return false;
}
if ((act == Wrapper::SET && !(access & WRITE)) ||
(act != Wrapper::SET && !(access & READ))) {
return false;
}
// Inspect the property on the underlying object to check for red flags.
if (!JS_GetPropertyDescriptorById(cx, wrappedObject, id, &desc))
return false;
// Reject accessor properties.
if (desc.hasGetterOrSetter()) {
EnterAndThrow(cx, wrapper, "Exposing privileged accessor properties is prohibited");
return false;
}
// Reject privileged or cross-origin callables.
if (desc.value().isObject()) {
RootedObject maybeCallable(cx, js::UncheckedUnwrap(&desc.value().toObject()));
if (JS::IsCallable(maybeCallable) && !AccessCheck::subsumes(wrapper, maybeCallable)) {
EnterAndThrow(cx, wrapper, "Exposing privileged or cross-origin callable is prohibited");
return false;
}
}
return true;
}
bool
ExposedPropertiesOnly::check(JSContext *cx, HandleObject wrapper, HandleId id, Wrapper::Action act)
{
RootedObject wrappedObject(cx, Wrapper::wrappedObject(wrapper));
if (act == Wrapper::CALL)
return true;
// For the case of getting a property descriptor, we allow if either GET or SET
// is allowed, and rely on FilteringWrapper to filter out any disallowed accessors.
if (act == Wrapper::GET_PROPERTY_DESCRIPTOR) {
return check(cx, wrapper, id, Wrapper::GET) ||
check(cx, wrapper, id, Wrapper::SET);
}
RootedId exposedPropsId(cx, GetRTIdByIndex(cx, XPCJSRuntime::IDX_EXPOSEDPROPS));
// We need to enter the wrappee's compartment to look at __exposedProps__,
// but we want to be in the wrapper's compartment if we call Deny().
//
// Unfortunately, |cx| can be in either compartment when we call ::check. :-(
JSAutoCompartment ac(cx, wrappedObject);
bool found = false;
if (!JS_HasPropertyById(cx, wrappedObject, exposedPropsId, &found))
return false;
// Always permit access to "length" and indexed properties of arrays.
if ((JS_IsArrayObject(cx, wrappedObject) ||
JS_IsTypedArrayObject(wrappedObject)) &&
((JSID_IS_INT(id) && JSID_TO_INT(id) >= 0) ||
(JSID_IS_STRING(id) && JS_FlatStringEqualsAscii(JSID_TO_FLAT_STRING(id), "length")))) {
return true; // Allow
}
// If no __exposedProps__ existed, deny access.
if (!found) {
return false;
}
if (id == JSID_VOID)
return true;
RootedValue exposedProps(cx);
if (!JS_LookupPropertyById(cx, wrappedObject, exposedPropsId, &exposedProps))
return false;
if (exposedProps.isNullOrUndefined())
return false;
if (!exposedProps.isObject()) {
EnterAndThrow(cx, wrapper, "__exposedProps__ must be undefined, null, or an Object");
return false;
}
RootedObject hallpass(cx, &exposedProps.toObject());
if (!AccessCheck::subsumes(js::UncheckedUnwrap(hallpass), wrappedObject)) {
EnterAndThrow(cx, wrapper, "Invalid __exposedProps__");
return false;
}
Access access = NO_ACCESS;
Rooted<JSPropertyDescriptor> desc(cx);
if (!JS_GetPropertyDescriptorById(cx, hallpass, id, &desc)) {
return false; // Error
}
if (!desc.object() || !desc.isEnumerable())
return false;
if (!desc.value().isString()) {
EnterAndThrow(cx, wrapper, "property must be a string");
return false;
}
JSFlatString *flat = JS_FlattenString(cx, desc.value().toString());
if (!flat)
return false;
size_t length = JS_GetStringLength(JS_FORGET_STRING_FLATNESS(flat));
for (size_t i = 0; i < length; ++i) {
char16_t ch = JS_GetFlatStringCharAt(flat, i);
switch (ch) {
case 'r':
if (access & READ) {
EnterAndThrow(cx, wrapper, "duplicate 'readable' property flag");
return false;
}
access = Access(access | READ);
break;
case 'w':
if (access & WRITE) {
EnterAndThrow(cx, wrapper, "duplicate 'writable' property flag");
return false;
}
access = Access(access | WRITE);
break;
default:
EnterAndThrow(cx, wrapper, "properties can only be readable or read and writable");
return false;
}
}
if (access == NO_ACCESS) {
EnterAndThrow(cx, wrapper, "specified properties must have a permission bit set");
return false;
}
if ((act == Wrapper::SET && !(access & WRITE)) ||
(act != Wrapper::SET && !(access & READ))) {
return false;
}
return true;
}