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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=4 sw=4 et 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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "JavaScriptParent.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/ScriptSettings.h"
#include "nsJSUtils.h"
#include "jsfriendapi.h"
#include "jswrapper.h"
#include "js/Proxy.h"
#include "js/HeapAPI.h"
#include "xpcprivate.h"
#include "mozilla/Casting.h"
#include "mozilla/Telemetry.h"
#include "nsAutoPtr.h"
using namespace js;
using namespace JS;
using namespace mozilla;
using namespace mozilla::jsipc;
using namespace mozilla::dom;
static void
TraceParent(JSTracer* trc, void* data)
{
static_cast<JavaScriptParent*>(data)->trace(trc);
}
JavaScriptParent::~JavaScriptParent()
{
JS_RemoveExtraGCRootsTracer(danger::GetJSContext(), TraceParent, this);
}
bool
JavaScriptParent::init()
{
if (!WrapperOwner::init())
return false;
JS_AddExtraGCRootsTracer(danger::GetJSContext(), TraceParent, this);
return true;
}
static bool
ForbidUnsafeBrowserCPOWs()
{
static bool result;
static bool cached = false;
if (!cached) {
cached = true;
Preferences::AddBoolVarCache(&result, "dom.ipc.cpows.forbid-unsafe-from-browser", false);
}
return result;
}
// Should we allow CPOWs in aAddonId, even though it's marked as multiprocess
// compatible? This is controlled by two prefs:
// If dom.ipc.cpows.forbid-cpows-in-compat-addons is false, then we allow the CPOW.
// If dom.ipc.cpows.forbid-cpows-in-compat-addons is true:
// We check if aAddonId is listed in dom.ipc.cpows.allow-cpows-in-compat-addons
// (which should be a comma-separated string). If it's present there, we allow
// the CPOW. Otherwise we forbid the CPOW.
static bool
ForbidCPOWsInCompatibleAddon(const nsACString& aAddonId)
{
bool forbid = Preferences::GetBool("dom.ipc.cpows.forbid-cpows-in-compat-addons", false);
if (!forbid) {
return false;
}
nsCString allow;
allow.Assign(',');
allow.Append(Preferences::GetCString("dom.ipc.cpows.allow-cpows-in-compat-addons"));
allow.Append(',');
nsCString searchString(",");
searchString.Append(aAddonId);
searchString.Append(',');
return allow.Find(searchString) == kNotFound;
}
bool
JavaScriptParent::allowMessage(JSContext* cx)
{
// If we're running browser code, then we allow all safe CPOWs and forbid
// unsafe CPOWs based on a pref (which defaults to forbidden). We also allow
// CPOWs unconditionally in selected globals (based on
// Cu.permitCPOWsInScope).
//
// If we're running add-on code, then we check if the add-on is multiprocess
// compatible (which eventually translates to a given setting of allowCPOWs
// on the scopw). If it's not compatible, then we allow the CPOW but
// warn. If it is marked as compatible, then we check the
// ForbidCPOWsInCompatibleAddon; see the comment there.
MessageChannel* channel = GetIPCChannel();
bool isSafe = channel->IsInTransaction();
bool warn = !isSafe;
nsIGlobalObject* global = dom::GetIncumbentGlobal();
JSObject* jsGlobal = global ? global->GetGlobalJSObject() : nullptr;
if (jsGlobal) {
JSAutoCompartment ac(cx, jsGlobal);
JSAddonId* addonId = JS::AddonIdOfObject(jsGlobal);
if (!xpc::CompartmentPrivate::Get(jsGlobal)->allowCPOWs) {
if (!addonId && ForbidUnsafeBrowserCPOWs() && !isSafe) {
Telemetry::Accumulate(Telemetry::BROWSER_SHIM_USAGE_BLOCKED, 1);
JS_ReportErrorASCII(cx, "unsafe CPOW usage forbidden");
return false;
}
if (addonId) {
JSFlatString* flat = JS_ASSERT_STRING_IS_FLAT(JS::StringOfAddonId(addonId));
nsString addonIdString;
AssignJSFlatString(addonIdString, flat);
NS_ConvertUTF16toUTF8 addonIdCString(addonIdString);
Telemetry::Accumulate(Telemetry::ADDON_FORBIDDEN_CPOW_USAGE, addonIdCString);
if (ForbidCPOWsInCompatibleAddon(addonIdCString)) {
JS_ReportErrorASCII(cx, "CPOW usage forbidden in this add-on");
return false;
}
warn = true;
}
}
}
if (!warn)
return true;
static bool disableUnsafeCPOWWarnings = PR_GetEnv("DISABLE_UNSAFE_CPOW_WARNINGS");
if (!disableUnsafeCPOWWarnings) {
nsCOMPtr<nsIConsoleService> console(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
if (console && cx) {
nsAutoString filename;
uint32_t lineno = 0, column = 0;
nsJSUtils::GetCallingLocation(cx, filename, &lineno, &column);
nsCOMPtr<nsIScriptError> error(do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
error->Init(NS_LITERAL_STRING("unsafe/forbidden CPOW usage"), filename,
EmptyString(), lineno, column,
nsIScriptError::warningFlag, "chrome javascript");
console->LogMessage(error);
} else {
NS_WARNING("Unsafe synchronous IPC message");
}
}
return true;
}
void
JavaScriptParent::trace(JSTracer* trc)
{
objects_.trace(trc);
unwaivedObjectIds_.trace(trc);
waivedObjectIds_.trace(trc);
}
JSObject*
JavaScriptParent::scopeForTargetObjects()
{
// CPWOWs from the child need to point into the parent's unprivileged junk
// scope so that a compromised child cannot compromise the parent. In
// practice, this means that a child process can only (a) hold parent
// objects alive and (b) invoke them if they are callable.
return xpc::UnprivilegedJunkScope();
}
void
JavaScriptParent::afterProcessTask()
{
if (savedNextCPOWNumber_ == nextCPOWNumber_)
return;
savedNextCPOWNumber_ = nextCPOWNumber_;
MOZ_ASSERT(nextCPOWNumber_ > 0);
if (active())
Unused << SendDropTemporaryStrongReferences(nextCPOWNumber_ - 1);
}
PJavaScriptParent*
mozilla::jsipc::NewJavaScriptParent()
{
JavaScriptParent* parent = new JavaScriptParent();
if (!parent->init()) {
delete parent;
return nullptr;
}
return parent;
}
void
mozilla::jsipc::ReleaseJavaScriptParent(PJavaScriptParent* parent)
{
static_cast<JavaScriptParent*>(parent)->decref();
}
void
mozilla::jsipc::AfterProcessTask()
{
for (auto* cp : ContentParent::AllProcesses(ContentParent::eLive)) {
if (PJavaScriptParent* p = LoneManagedOrNullAsserts(cp->ManagedPJavaScriptParent()))
static_cast<JavaScriptParent*>(p)->afterProcessTask();
}
}
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