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Diffstat (limited to 'js/xpconnect/src/ExportHelpers.cpp')
| -rw-r--r-- | js/xpconnect/src/ExportHelpers.cpp | 491 |
1 files changed, 491 insertions, 0 deletions
diff --git a/js/xpconnect/src/ExportHelpers.cpp b/js/xpconnect/src/ExportHelpers.cpp new file mode 100644 index 000000000..3dbf83e3b --- /dev/null +++ b/js/xpconnect/src/ExportHelpers.cpp @@ -0,0 +1,491 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* vim: set ts=8 sts=4 et sw=4 tw=99: */ +/* 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 "xpcprivate.h" +#include "WrapperFactory.h" +#include "AccessCheck.h" +#include "jsfriendapi.h" +#include "jswrapper.h" +#include "js/Proxy.h" +#include "mozilla/dom/BindingUtils.h" +#include "mozilla/dom/BlobBinding.h" +#include "mozilla/dom/File.h" +#include "mozilla/dom/FileListBinding.h" +#include "mozilla/dom/StructuredCloneHolder.h" +#include "nsGlobalWindow.h" +#include "nsJSUtils.h" +#include "nsIDOMFileList.h" + +using namespace mozilla; +using namespace mozilla::dom; +using namespace JS; + +namespace xpc { + +bool +IsReflector(JSObject* obj) +{ + obj = js::CheckedUnwrap(obj, /* stopAtWindowProxy = */ false); + if (!obj) + return false; + return IS_WN_REFLECTOR(obj) || dom::IsDOMObject(obj); +} + +enum StackScopedCloneTags { + SCTAG_BASE = JS_SCTAG_USER_MIN, + SCTAG_REFLECTOR, + SCTAG_BLOB, + SCTAG_FUNCTION, +}; + +// The HTML5 structured cloning algorithm includes a few DOM objects, notably +// FileList. That wouldn't in itself be a reason to support them here, +// but we've historically supported them for Cu.cloneInto (where we didn't support +// other reflectors), so we need to continue to do so in the wrapReflectors == false +// case to maintain compatibility. +// +// FileList clones are supposed to give brand new objects, rather than +// cross-compartment wrappers. For this, our current implementation relies on the +// fact that these objects are implemented with XPConnect and have one reflector +// per scope. +bool IsFileList(JSObject* obj) +{ + return IS_INSTANCE_OF(FileList, obj); +} + +class MOZ_STACK_CLASS StackScopedCloneData + : public StructuredCloneHolderBase +{ +public: + StackScopedCloneData(JSContext* aCx, StackScopedCloneOptions* aOptions) + : mOptions(aOptions) + , mReflectors(aCx) + , mFunctions(aCx) + {} + + ~StackScopedCloneData() + { + Clear(); + } + + JSObject* CustomReadHandler(JSContext* aCx, + JSStructuredCloneReader* aReader, + uint32_t aTag, + uint32_t aData) + { + if (aTag == SCTAG_REFLECTOR) { + MOZ_ASSERT(!aData); + + size_t idx; + if (!JS_ReadBytes(aReader, &idx, sizeof(size_t))) + return nullptr; + + RootedObject reflector(aCx, mReflectors[idx]); + MOZ_ASSERT(reflector, "No object pointer?"); + MOZ_ASSERT(IsReflector(reflector), "Object pointer must be a reflector!"); + + if (!JS_WrapObject(aCx, &reflector)) + return nullptr; + + return reflector; + } + + if (aTag == SCTAG_FUNCTION) { + MOZ_ASSERT(aData < mFunctions.length()); + + RootedValue functionValue(aCx); + RootedObject obj(aCx, mFunctions[aData]); + + if (!JS_WrapObject(aCx, &obj)) + return nullptr; + + FunctionForwarderOptions forwarderOptions; + if (!xpc::NewFunctionForwarder(aCx, JSID_VOIDHANDLE, obj, forwarderOptions, + &functionValue)) + { + return nullptr; + } + + return &functionValue.toObject(); + } + + if (aTag == SCTAG_BLOB) { + MOZ_ASSERT(!aData); + + size_t idx; + if (!JS_ReadBytes(aReader, &idx, sizeof(size_t))) { + return nullptr; + } + + nsIGlobalObject* global = xpc::NativeGlobal(JS::CurrentGlobalOrNull(aCx)); + MOZ_ASSERT(global); + + // RefPtr<File> needs to go out of scope before toObjectOrNull() is called because + // otherwise the static analysis thinks it can gc the JSObject via the stack. + JS::Rooted<JS::Value> val(aCx); + { + RefPtr<Blob> blob = Blob::Create(global, mBlobImpls[idx]); + if (!ToJSValue(aCx, blob, &val)) { + return nullptr; + } + } + + return val.toObjectOrNull(); + } + + MOZ_ASSERT_UNREACHABLE("Encountered garbage in the clone stream!"); + return nullptr; + } + + bool CustomWriteHandler(JSContext* aCx, + JSStructuredCloneWriter* aWriter, + JS::Handle<JSObject*> aObj) + { + { + JS::Rooted<JSObject*> obj(aCx, aObj); + Blob* blob = nullptr; + if (NS_SUCCEEDED(UNWRAP_OBJECT(Blob, &obj, blob))) { + BlobImpl* blobImpl = blob->Impl(); + MOZ_ASSERT(blobImpl); + + if (!mBlobImpls.AppendElement(blobImpl)) + return false; + + size_t idx = mBlobImpls.Length() - 1; + return JS_WriteUint32Pair(aWriter, SCTAG_BLOB, 0) && + JS_WriteBytes(aWriter, &idx, sizeof(size_t)); + } + } + + if ((mOptions->wrapReflectors && IsReflector(aObj)) || + IsFileList(aObj)) + { + if (!mReflectors.append(aObj)) + return false; + + size_t idx = mReflectors.length() - 1; + if (!JS_WriteUint32Pair(aWriter, SCTAG_REFLECTOR, 0)) + return false; + if (!JS_WriteBytes(aWriter, &idx, sizeof(size_t))) + return false; + return true; + } + + if (JS::IsCallable(aObj)) { + if (mOptions->cloneFunctions) { + if (!mFunctions.append(aObj)) + return false; + return JS_WriteUint32Pair(aWriter, SCTAG_FUNCTION, mFunctions.length() - 1); + } else { + JS_ReportErrorASCII(aCx, "Permission denied to pass a Function via structured clone"); + return false; + } + } + + JS_ReportErrorASCII(aCx, "Encountered unsupported value type writing stack-scoped structured clone"); + return false; + } + + StackScopedCloneOptions* mOptions; + AutoObjectVector mReflectors; + AutoObjectVector mFunctions; + nsTArray<RefPtr<BlobImpl>> mBlobImpls; +}; + +/* + * General-purpose structured-cloning utility for cases where the structured + * clone buffer is only used in stack-scope (that is to say, the buffer does + * not escape from this function). The stack-scoping allows us to pass + * references to various JSObjects directly in certain situations without + * worrying about lifetime issues. + * + * This function assumes that |cx| is already entered the compartment we want + * to clone to, and that |val| may not be same-compartment with cx. When the + * function returns, |val| is set to the result of the clone. + */ +bool +StackScopedClone(JSContext* cx, StackScopedCloneOptions& options, + MutableHandleValue val) +{ + StackScopedCloneData data(cx, &options); + { + // For parsing val we have to enter its compartment. + // (unless it's a primitive) + Maybe<JSAutoCompartment> ac; + if (val.isObject()) { + ac.emplace(cx, &val.toObject()); + } else if (val.isString() && !JS_WrapValue(cx, val)) { + return false; + } + + if (!data.Write(cx, val)) + return false; + } + + // Now recreate the clones in the target compartment. + if (!data.Read(cx, val)) + return false; + + // Deep-freeze if requested. + if (options.deepFreeze && val.isObject()) { + RootedObject obj(cx, &val.toObject()); + if (!JS_DeepFreezeObject(cx, obj)) + return false; + } + + return true; +} + +// Note - This function mirrors the logic of CheckPassToChrome in +// ChromeObjectWrapper.cpp. +static bool +CheckSameOriginArg(JSContext* cx, FunctionForwarderOptions& options, HandleValue v) +{ + // Consumers can explicitly opt out of this security check. This is used in + // the web console to allow the utility functions to accept cross-origin Windows. + if (options.allowCrossOriginArguments) + return true; + + // Primitives are fine. + if (!v.isObject()) + return true; + RootedObject obj(cx, &v.toObject()); + MOZ_ASSERT(js::GetObjectCompartment(obj) != js::GetContextCompartment(cx), + "This should be invoked after entering the compartment but before " + "wrapping the values"); + + // Non-wrappers are fine. + if (!js::IsWrapper(obj)) + return true; + + // Wrappers leading back to the scope of the exported function are fine. + if (js::GetObjectCompartment(js::UncheckedUnwrap(obj)) == js::GetContextCompartment(cx)) + return true; + + // Same-origin wrappers are fine. + if (AccessCheck::wrapperSubsumes(obj)) + return true; + + // Badness. + JS_ReportErrorASCII(cx, "Permission denied to pass object to exported function"); + return false; +} + +static bool +FunctionForwarder(JSContext* cx, unsigned argc, Value* vp) +{ + CallArgs args = CallArgsFromVp(argc, vp); + + // Grab the options from the reserved slot. + RootedObject optionsObj(cx, &js::GetFunctionNativeReserved(&args.callee(), 1).toObject()); + FunctionForwarderOptions options(cx, optionsObj); + if (!options.Parse()) + return false; + + // Grab and unwrap the underlying callable. + RootedValue v(cx, js::GetFunctionNativeReserved(&args.callee(), 0)); + RootedObject unwrappedFun(cx, js::UncheckedUnwrap(&v.toObject())); + + RootedObject thisObj(cx, args.isConstructing() ? nullptr : JS_THIS_OBJECT(cx, vp)); + { + // We manually implement the contents of CrossCompartmentWrapper::call + // here, because certain function wrappers (notably content->nsEP) are + // not callable. + JSAutoCompartment ac(cx, unwrappedFun); + + RootedValue thisVal(cx, ObjectOrNullValue(thisObj)); + if (!CheckSameOriginArg(cx, options, thisVal) || !JS_WrapObject(cx, &thisObj)) + return false; + + for (size_t n = 0; n < args.length(); ++n) { + if (!CheckSameOriginArg(cx, options, args[n]) || !JS_WrapValue(cx, args[n])) + return false; + } + + RootedValue fval(cx, ObjectValue(*unwrappedFun)); + if (args.isConstructing()) { + RootedObject obj(cx); + if (!JS::Construct(cx, fval, args, &obj)) + return false; + args.rval().setObject(*obj); + } else { + if (!JS_CallFunctionValue(cx, thisObj, fval, args, args.rval())) + return false; + } + } + + // Rewrap the return value into our compartment. + return JS_WrapValue(cx, args.rval()); +} + +bool +NewFunctionForwarder(JSContext* cx, HandleId idArg, HandleObject callable, + FunctionForwarderOptions& options, MutableHandleValue vp) +{ + RootedId id(cx, idArg); + if (id == JSID_VOIDHANDLE) + id = GetJSIDByIndex(cx, XPCJSContext::IDX_EMPTYSTRING); + + // We have no way of knowing whether the underlying function wants to be a + // constructor or not, so we just mark all forwarders as constructors, and + // let the underlying function throw for construct calls if it wants. + JSFunction* fun = js::NewFunctionByIdWithReserved(cx, FunctionForwarder, + 0, JSFUN_CONSTRUCTOR, id); + if (!fun) + return false; + + // Stash the callable in slot 0. + AssertSameCompartment(cx, callable); + RootedObject funobj(cx, JS_GetFunctionObject(fun)); + js::SetFunctionNativeReserved(funobj, 0, ObjectValue(*callable)); + + // Stash the options in slot 1. + RootedObject optionsObj(cx, options.ToJSObject(cx)); + if (!optionsObj) + return false; + js::SetFunctionNativeReserved(funobj, 1, ObjectValue(*optionsObj)); + + vp.setObject(*funobj); + return true; +} + +bool +ExportFunction(JSContext* cx, HandleValue vfunction, HandleValue vscope, HandleValue voptions, + MutableHandleValue rval) +{ + bool hasOptions = !voptions.isUndefined(); + if (!vscope.isObject() || !vfunction.isObject() || (hasOptions && !voptions.isObject())) { + JS_ReportErrorASCII(cx, "Invalid argument"); + return false; + } + + RootedObject funObj(cx, &vfunction.toObject()); + RootedObject targetScope(cx, &vscope.toObject()); + ExportFunctionOptions options(cx, hasOptions ? &voptions.toObject() : nullptr); + if (hasOptions && !options.Parse()) + return false; + + // Restrictions: + // * We must subsume the scope we are exporting to. + // * We must subsume the function being exported, because the function + // forwarder manually circumvents security wrapper CALL restrictions. + targetScope = js::CheckedUnwrap(targetScope); + funObj = js::CheckedUnwrap(funObj); + if (!targetScope || !funObj) { + JS_ReportErrorASCII(cx, "Permission denied to export function into scope"); + return false; + } + + if (js::IsScriptedProxy(targetScope)) { + JS_ReportErrorASCII(cx, "Defining property on proxy object is not allowed"); + return false; + } + + { + // We need to operate in the target scope from here on, let's enter + // its compartment. + JSAutoCompartment ac(cx, targetScope); + + // Unwrapping to see if we have a callable. + funObj = UncheckedUnwrap(funObj); + if (!JS::IsCallable(funObj)) { + JS_ReportErrorASCII(cx, "First argument must be a function"); + return false; + } + + RootedId id(cx, options.defineAs); + if (JSID_IS_VOID(id)) { + // If there wasn't any function name specified, + // copy the name from the function being imported. + JSFunction* fun = JS_GetObjectFunction(funObj); + RootedString funName(cx, JS_GetFunctionId(fun)); + if (!funName) + funName = JS_AtomizeAndPinString(cx, ""); + + if (!JS_StringToId(cx, funName, &id)) + return false; + } + MOZ_ASSERT(JSID_IS_STRING(id)); + + // The function forwarder will live in the target compartment. Since + // this function will be referenced from its private slot, to avoid a + // GC hazard, we must wrap it to the same compartment. + if (!JS_WrapObject(cx, &funObj)) + return false; + + // And now, let's create the forwarder function in the target compartment + // for the function the be exported. + FunctionForwarderOptions forwarderOptions; + forwarderOptions.allowCrossOriginArguments = options.allowCrossOriginArguments; + if (!NewFunctionForwarder(cx, id, funObj, forwarderOptions, rval)) { + JS_ReportErrorASCII(cx, "Exporting function failed"); + return false; + } + + // We have the forwarder function in the target compartment. If + // defineAs was set, we also need to define it as a property on + // the target. + if (!JSID_IS_VOID(options.defineAs)) { + if (!JS_DefinePropertyById(cx, targetScope, id, rval, + JSPROP_ENUMERATE, + JS_STUBGETTER, JS_STUBSETTER)) { + return false; + } + } + } + + // Finally we have to re-wrap the exported function back to the caller compartment. + if (!JS_WrapValue(cx, rval)) + return false; + + return true; +} + +bool +CreateObjectIn(JSContext* cx, HandleValue vobj, CreateObjectInOptions& options, + MutableHandleValue rval) +{ + if (!vobj.isObject()) { + JS_ReportErrorASCII(cx, "Expected an object as the target scope"); + return false; + } + + RootedObject scope(cx, js::CheckedUnwrap(&vobj.toObject())); + if (!scope) { + JS_ReportErrorASCII(cx, "Permission denied to create object in the target scope"); + return false; + } + + bool define = !JSID_IS_VOID(options.defineAs); + + if (define && js::IsScriptedProxy(scope)) { + JS_ReportErrorASCII(cx, "Defining property on proxy object is not allowed"); + return false; + } + + RootedObject obj(cx); + { + JSAutoCompartment ac(cx, scope); + obj = JS_NewPlainObject(cx); + if (!obj) + return false; + + if (define) { + if (!JS_DefinePropertyById(cx, scope, options.defineAs, obj, + JSPROP_ENUMERATE, + JS_STUBGETTER, JS_STUBSETTER)) + return false; + } + } + + rval.setObject(*obj); + if (!WrapperFactory::WaiveXrayAndWrap(cx, rval)) + return false; + + return true; +} + +} /* namespace xpc */ |