Bug 1809518 - Use stencil parsing to do the Javascript check for ORB in Utility Process r=farre,smaug,tcampbell

This patch allows JS Validator to parse the incoming data into
stencil to verify if its a Javascript file.

Differential Revision: https://phabricator.services.mozilla.com/D166484

dom/ipc/JSOracleChild.cpp

@@ -15,6 +15,28 @@ using namespace mozilla::dom;
 
 static mozilla::StaticRefPtr<JSOracleChild> sOracleSingletonChild;
 
+static mozilla::StaticAutoPtr<JSContextHolder> sJSContextHolder;
+
+/* static */
+void JSContextHolder::MaybeInit() {
+  if (!sJSContextHolder) {
+    sJSContextHolder = new JSContextHolder();
+    ClearOnShutdown(&sJSContextHolder);
+  }
+}
+
+/* static */
+JSContext* JSOracleChild::JSContext() {
+  MOZ_ASSERT(sJSContextHolder);
+  return sJSContextHolder->mCx;
+}
+
+/* static */
+JSObject* JSOracleChild::JSObject() {
+  MOZ_ASSERT(sJSContextHolder);
+  return sJSContextHolder->mGlobal;
+}
+
 JSOracleChild* JSOracleChild::GetSingleton() {
   MOZ_ASSERT(NS_IsMainThread());
   if (!sOracleSingletonChild) {
@@ -30,5 +52,6 @@ already_AddRefed<PJSValidatorChild> JSOracleChild::AllocPJSValidatorChild() {
 
 void JSOracleChild::Start(Endpoint<PJSOracleChild>&& aEndpoint) {
   DebugOnly<bool> ok = std::move(aEndpoint).Bind(this);
+  JSContextHolder::MaybeInit();
   MOZ_ASSERT(ok);
 }

dom/ipc/JSOracleChild.h

@@ -9,10 +9,60 @@
 
 #include "mozilla/dom/PJSOracleChild.h"
 
+#include "js/CharacterEncoding.h"
+#include "js/HeapAPI.h"
+#include "js/Initialization.h"
+#include "jsapi.h"
+#include "js/CompilationAndEvaluation.h"
+#include "js/Context.h"
+
 namespace mozilla::ipc {
 class UtilityProcessParent;
 }
+
 namespace mozilla::dom {
+struct JSContextHolder {
+  JSContextHolder() {
+    MOZ_RELEASE_ASSERT(JS_IsInitialized(),
+                       "UtilityProcessChild::Init should have JS initialized");
+
+    mCx = JS_NewContext(JS::DefaultHeapMaxBytes);
+    if (!mCx) {
+      MOZ_CRASH("Failed to create JS Context");
+      return;
+    }
+
+    if (!JS::InitSelfHostedCode(mCx)) {
+      MOZ_CRASH("Failed to initialize the runtime's self-hosted code");
+      return;
+    }
+
+    static JSClass jsValidatorGlobalClass = {
+        "JSValidatorGlobal", JSCLASS_GLOBAL_FLAGS, &JS::DefaultGlobalClassOps};
+
+    JS::Rooted<JSObject*> global(
+        mCx, JS_NewGlobalObject(mCx, &jsValidatorGlobalClass, nullptr,
+                                JS::FireOnNewGlobalHook, JS::RealmOptions()));
+
+    if (!global) {
+      MOZ_CRASH("Failed to create the global");
+      return;
+    }
+
+    mGlobal.init(mCx, global);
+  }
+
+  ~JSContextHolder() {
+    if (mCx) {
+      JS_DestroyContext(mCx);
+    }
+  }
+
+  static void MaybeInit();
+
+  JSContext* mCx;
+  JS::PersistentRooted<JSObject*> mGlobal;
+};
 
 class PJSValidatorChild;
 
@@ -24,6 +74,9 @@ class JSOracleChild final : public PJSOracleChild {
 
   void Start(Endpoint<PJSOracleChild>&& aEndpoint);
 
+  static JSContext* JSContext();
+  static JSObject* JSObject();
+
  private:
   ~JSOracleChild() = default;
 

dom/ipc/JSValidatorChild.cpp

@@ -5,8 +5,18 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/JSValidatorChild.h"
+#include "js/JSON.h"
+#include "mozilla/dom/JSOracleChild.h"
+
 #include "mozilla/ipc/Endpoint.h"
 
+#include "js/experimental/JSStencil.h"
+#include "js/SourceText.h"
+#include "js/Exception.h"
+#include "js/GlobalObject.h"
+#include "js/CompileOptions.h"
+#include "js/RealmOptions.h"
+
 using namespace mozilla::dom;
 
 mozilla::ipc::IPCResult JSValidatorChild::RecvIsOpaqueResponseAllowed(
@@ -72,16 +82,42 @@ void JSValidatorChild::Resolve(ValidatorResult aResult) {
 }
 
 JSValidatorChild::ValidatorResult JSValidatorChild::ShouldAllowJS() const {
-  // mSourceBytes could be empty when
-  // 1. No OnDataAvailable calls
-  // 2. Failed to allocate shmem
-
   // The empty document parses as JavaScript, so for clarity we have a condition
   // separately for that.
   if (mSourceBytes.IsEmpty()) {
     return ValidatorResult::JavaScript;
   }
 
+  JSContext* cx = JSOracleChild::JSContext();
+  if (!cx) {
+    return ValidatorResult::Failure;
+  }
+
+  JSObject* global = JSOracleChild::JSObject();
+  if (!global) {
+    return ValidatorResult::Failure;
+  }
+
+  JS::SourceText<Utf8Unit> srcBuf;
+  if (!srcBuf.init(cx, mSourceBytes.BeginReading(), mSourceBytes.Length(),
+                   JS::SourceOwnership::Borrowed)) {
+    JS_ClearPendingException(cx);
+    return ValidatorResult::Failure;
+  }
+
+  JSAutoRealm ar(cx, global);
+
+  // Parse to JavaScript
+  RefPtr<JS::Stencil> stencil =
+      CompileGlobalScriptToStencil(cx, JS::CompileOptions(cx), srcBuf);
+
+  if (!stencil) {
+    JS_ClearPendingException(cx);
+    return ValidatorResult::Other;
+  }
+
+  // The stencil parsing lacks the JSON support, so we have to do the
+  // JSON parsing separately.
   if (StringBeginsWith(NS_ConvertUTF8toUTF16(mSourceBytes), u"{"_ns)) {
     return ValidatorResult::JSON;
   }

dom/ipc/JSValidatorParent.cpp

@@ -39,6 +39,9 @@ void JSValidatorParent::IsOpaqueResponseAllowed(
               Tie(data, result) = aResult.ResolveValue();
               aCallback(std::move(data), result);
             } else {
+              // For cases like the Utility Process crashes, the promise will be
+              // rejected due to sending failures, and we'll block the request
+              // since we can't validate it.
               aCallback(Nothing(), ValidatorResult::Failure);
             }
           });

ipc/glue/UtilityProcessChild.cpp

@@ -110,6 +110,15 @@ bool UtilityProcessChild::Init(mozilla::ipc::UntypedEndpoint&& aEndpoint,
 
   mSandbox = (SandboxingKind)aSandboxingKind;
 
+  // At the moment, only ORB uses JSContext in the
+  // Utility Process and ORB uses GENERIC_UTILITY
+  if (mSandbox == SandboxingKind::GENERIC_UTILITY) {
+    JS::DisableJitBackend();
+    if (!JS_Init()) {
+      return false;
+    }
+  }
+
   profiler_set_process_name(nsCString("Utility Process"));
 
   // Notify the parent process that we have finished our init and that it can
@@ -117,9 +126,12 @@ bool UtilityProcessChild::Init(mozilla::ipc::UntypedEndpoint&& aEndpoint,
   SendInitCompleted();
 
   RunOnShutdown(
-      [] {
+      [sandboxKind = mSandbox] {
         StaticMutexAutoLock lock(sUtilityProcessChildMutex);
         sUtilityProcessChild = nullptr;
+        if (sandboxKind == SandboxingKind::GENERIC_UTILITY) {
+          JS_ShutDown();
+        }
       },
       ShutdownPhase::XPCOMShutdownFinal);
 

js/src/gc/Memory.cpp

@@ -11,6 +11,7 @@
 #include "mozilla/RandomNum.h"
 #include "mozilla/TaggedAnonymousMemory.h"
 
+#include "jit/JitOptions.h"
 #include "js/HeapAPI.h"
 #include "js/Utility.h"
 #include "util/Memory.h"
@@ -402,10 +403,12 @@ void InitMemorySubsystem() {
     numAddressBits = 32;
 #endif
 #ifdef RLIMIT_AS
-    rlimit as_limit;
-    if (getrlimit(RLIMIT_AS, &as_limit) == 0 &&
-        as_limit.rlim_max != RLIM_INFINITY) {
-      virtualMemoryLimit = as_limit.rlim_max;
+    if (jit::HasJitBackend()) {
+      rlimit as_limit;
+      if (getrlimit(RLIMIT_AS, &as_limit) == 0 &&
+          as_limit.rlim_max != RLIM_INFINITY) {
+        virtualMemoryLimit = as_limit.rlim_max;
+      }
     }
 #endif
   }

testing/web-platform/meta/fetch/orb/tentative/__dir__.ini

@@ -1 +1 @@
-prefs: [browser.opaqueResponseBlocking:true]
+prefs: [browser.opaqueResponseBlocking:true, browser.opaqueResponseBlocking.javascriptValidator:true]

testing/web-platform/meta/fetch/orb/tentative/known-mime-type.sub.any.js.ini

@@ -1,30 +0,0 @@
-[known-mime-type.sub.any.worker.html]
-  prefs: [browser.opaqueResponseBlocking.javascriptValidator:true]
-  [ORB should block opaque font/ttf]
-    expected: FAIL
-
-  [ORB should block opaque text/plain]
-    expected: FAIL
-
-  [ORB should block opaque application/json]
-    expected:
-      if not debug and (os == "mac"): [PASS, FAIL]
-      if not debug and (os == "linux"): [PASS, FAIL]
-      if not debug and (os == "android"): [PASS, FAIL]
-
-
-[known-mime-type.sub.any.html]
-  prefs: [browser.opaqueResponseBlocking.javascriptValidator:true]
-  expected:
-    if (os == "android") and fission: TIMEOUT
-  [ORB should block opaque font/ttf]
-    expected: FAIL
-
-  [ORB should block opaque text/plain]
-    expected: FAIL
-
-  [ORB should block opaque application/json]
-    expected:
-      if not debug and (os == "linux"): [PASS, FAIL]
-      if not debug and (os == "android"): [PASS, FAIL]
-      if not debug and (os == "mac"): [PASS, FAIL]

testing/web-platform/tests/fetch/orb/resources/empty.json

@@ -0,0 +1 @@
+{}

testing/web-platform/tests/fetch/orb/tentative/known-mime-type.sub.any.js

@@ -29,7 +29,17 @@ promise_test(
       TypeError,
       fetchORB(`${path}/data.json`, null, contentType("application/json"))
     ),
-  "ORB should block opaque application/json"
+  "ORB should block opaque application/json (non-empty)"
+);
+
+promise_test(
+  t =>
+    promise_rejects_js(
+      t,
+      TypeError,
+      fetchORB(`${path}/empty.json`, null, contentType("application/json"))
+    ),
+  "ORB should block opaque application/json (empty)"
 );
 
 promise_test(async () => {