From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jeremy Rose <japthorp@slack-corp.com>
Date: Tue, 21 Jun 2022 10:04:21 -0700
Subject: support V8 sandboxed pointers

This refactors several allocators to allocate within the V8 memory cage,
allowing them to be compatible with the V8_SANDBOXED_POINTERS feature.

diff --git a/src/api/environment.cc b/src/api/environment.cc
index 33edf44239a7ec13ebee2f926b1e7f9b8d0b83fe..11f8b8dea7bf4119c2d99ee451e3f1bc7bde8902 100644
--- a/src/api/environment.cc
+++ b/src/api/environment.cc
@@ -101,6 +101,14 @@ MaybeLocal<Value> PrepareStackTraceCallback(Local<Context> context,
   return result;
 }
 
+NodeArrayBufferAllocator::NodeArrayBufferAllocator() {
+  zero_fill_field_ = static_cast<uint32_t*>(allocator_->Allocate(sizeof(*zero_fill_field_)));
+}
+
+NodeArrayBufferAllocator::~NodeArrayBufferAllocator() {
+  allocator_->Free(zero_fill_field_, sizeof(*zero_fill_field_));
+}
+
 void* NodeArrayBufferAllocator::Allocate(size_t size) {
   void* ret;
   if (zero_fill_field_ || per_process::cli_options->zero_fill_all_buffers)
diff --git a/src/crypto/crypto_util.cc b/src/crypto/crypto_util.cc
index 3034b114e081e2b32dd5b71653927a41af7d48df..49b0175c219d75dd3a038687f353b2428fbdf62b 100644
--- a/src/crypto/crypto_util.cc
+++ b/src/crypto/crypto_util.cc
@@ -348,10 +348,35 @@ ByteSource& ByteSource::operator=(ByteSource&& other) noexcept {
   return *this;
 }
 
-std::unique_ptr<BackingStore> ByteSource::ReleaseToBackingStore() {
+std::unique_ptr<BackingStore> ByteSource::ReleaseToBackingStore(Environment* env) {
   // It's ok for allocated_data_ to be nullptr but
   // only if size_ is zero.
   CHECK_IMPLIES(size_ > 0, allocated_data_ != nullptr);
+#if defined(V8_ENABLE_SANDBOX)
+  // When V8 sandboxed pointers are enabled, we have to copy into the memory
+  // cage. We still want to ensure we erase the data on free though, so
+  // provide a custom deleter that calls OPENSSL_cleanse.
+  if (!size())
+    return ArrayBuffer::NewBackingStore(env->isolate(), 0);
+  std::unique_ptr<ArrayBuffer::Allocator> allocator(ArrayBuffer::Allocator::NewDefaultAllocator());
+  void* v8_data = allocator->Allocate(size());
+  CHECK(v8_data);
+  memcpy(v8_data, allocated_data_, size());
+  OPENSSL_clear_free(allocated_data_, size());
+  std::unique_ptr<BackingStore> ptr = ArrayBuffer::NewBackingStore(
+      v8_data,
+      size(),
+      [](void* data, size_t length, void*) {
+        OPENSSL_cleanse(data, length);
+        std::unique_ptr<ArrayBuffer::Allocator> allocator(ArrayBuffer::Allocator::NewDefaultAllocator());
+        allocator->Free(data, length);
+      }, nullptr);
+  CHECK(ptr);
+  allocated_data_ = nullptr;
+  data_ = nullptr;
+  size_ = 0;
+  return ptr;
+#else
   std::unique_ptr<BackingStore> ptr = ArrayBuffer::NewBackingStore(
       allocated_data_,
       size(),
@@ -363,10 +388,11 @@ std::unique_ptr<BackingStore> ByteSource::ReleaseToBackingStore() {
   data_ = nullptr;
   size_ = 0;
   return ptr;
+#endif  // defined(V8_ENABLE_SANDBOX)
 }
 
 Local<ArrayBuffer> ByteSource::ToArrayBuffer(Environment* env) {
-  std::unique_ptr<BackingStore> store = ReleaseToBackingStore();
+  std::unique_ptr<BackingStore> store = ReleaseToBackingStore(env);
   return ArrayBuffer::New(env->isolate(), std::move(store));
 }
 
@@ -702,6 +728,16 @@ namespace {
 // in which case this has the same semantics as
 // using OPENSSL_malloc. However, if the secure heap is
 // initialized, SecureBuffer will automatically use it.
+#if defined(V8_ENABLE_SANDBOX)
+// When V8 sandboxed pointers are enabled, the secure heap cannot be used as
+// all ArrayBuffers must be allocated inside the V8 memory cage.
+void SecureBuffer(const FunctionCallbackInfo<Value>& args) {
+  CHECK(args[0]->IsUint32());
+  uint32_t len = args[0].As<Uint32>()->Value();
+  Local<ArrayBuffer> buffer = ArrayBuffer::New(args.GetIsolate(), len);
+  args.GetReturnValue().Set(Uint8Array::New(buffer, 0, len));
+}
+#else
 void SecureBuffer(const FunctionCallbackInfo<Value>& args) {
   CHECK(args[0]->IsUint32());
   Environment* env = Environment::GetCurrent(args);
@@ -723,6 +759,7 @@ void SecureBuffer(const FunctionCallbackInfo<Value>& args) {
   Local<ArrayBuffer> buffer = ArrayBuffer::New(env->isolate(), store);
   args.GetReturnValue().Set(Uint8Array::New(buffer, 0, len));
 }
+#endif  // defined(V8_ENABLE_SANDBOX)
 
 void SecureHeapUsed(const FunctionCallbackInfo<Value>& args) {
 #ifndef OPENSSL_IS_BORINGSSL
diff --git a/src/crypto/crypto_util.h b/src/crypto/crypto_util.h
index 1ce5f35a70a7c855796cc96d4201cc996907cf8f..be700c953d55b35bd2fee7fd872efd9ed2600c63 100644
--- a/src/crypto/crypto_util.h
+++ b/src/crypto/crypto_util.h
@@ -280,7 +280,7 @@ class ByteSource {
   // Creates a v8::BackingStore that takes over responsibility for
   // any allocated data. The ByteSource will be reset with size = 0
   // after being called.
-  std::unique_ptr<v8::BackingStore> ReleaseToBackingStore();
+  std::unique_ptr<v8::BackingStore> ReleaseToBackingStore(Environment* env);
 
   v8::Local<v8::ArrayBuffer> ToArrayBuffer(Environment* env);
 
diff --git a/src/node_i18n.cc b/src/node_i18n.cc
index d45325954d980724f80d49298bbe837197237a9b..ccea18080142bd9cba3765dbbec61c2a63406667 100644
--- a/src/node_i18n.cc
+++ b/src/node_i18n.cc
@@ -105,7 +105,7 @@ namespace {
 
 template <typename T>
 MaybeLocal<Object> ToBufferEndian(Environment* env, MaybeStackBuffer<T>* buf) {
-  MaybeLocal<Object> ret = Buffer::New(env, buf);
+  MaybeLocal<Object> ret = Buffer::Copy(env, reinterpret_cast<char*>(buf->out()), buf->length() * sizeof(T));
   if (ret.IsEmpty())
     return ret;
 
diff --git a/src/node_internals.h b/src/node_internals.h
index 9a96e042fc5cda18beb13b89965a6267fba3e0a6..bd210db0b6ad12075e8ced8b321da38752b3d050 100644
--- a/src/node_internals.h
+++ b/src/node_internals.h
@@ -112,7 +112,9 @@ v8::Maybe<bool> InitializePrimordials(v8::Local<v8::Context> context);
 
 class NodeArrayBufferAllocator : public ArrayBufferAllocator {
  public:
-  inline uint32_t* zero_fill_field() { return &zero_fill_field_; }
+  NodeArrayBufferAllocator();
+  ~NodeArrayBufferAllocator() override;
+  inline uint32_t* zero_fill_field() { return zero_fill_field_; }
 
   void* Allocate(size_t size) override;  // Defined in src/node.cc
   void* AllocateUninitialized(size_t size) override;
@@ -131,7 +133,7 @@ class NodeArrayBufferAllocator : public ArrayBufferAllocator {
   }
 
  private:
-  uint32_t zero_fill_field_ = 1;  // Boolean but exposed as uint32 to JS land.
+  uint32_t* zero_fill_field_ = nullptr;  // Boolean but exposed as uint32 to JS land.
   std::atomic<size_t> total_mem_usage_ {0};
 
   // Delegate to V8's allocator for compatibility with the V8 memory cage.
diff --git a/src/node_serdes.cc b/src/node_serdes.cc
index 6698a1df81cb4e0947c86fb30c2d77fca8e2d9d1..dad297652b347819805b09fbfd869f1d037e31c1 100644
--- a/src/node_serdes.cc
+++ b/src/node_serdes.cc
@@ -29,6 +29,11 @@ using v8::ValueSerializer;
 
 namespace serdes {
 
+v8::ArrayBuffer::Allocator* GetAllocator() {
+  static v8::ArrayBuffer::Allocator* allocator = v8::ArrayBuffer::Allocator::NewDefaultAllocator();
+  return allocator;
+}
+
 class SerializerContext : public BaseObject,
                           public ValueSerializer::Delegate {
  public:
@@ -37,10 +42,15 @@ class SerializerContext : public BaseObject,
 
   ~SerializerContext() override = default;
 
+  // v8::ValueSerializer::Delegate
   void ThrowDataCloneError(Local<String> message) override;
   Maybe<bool> WriteHostObject(Isolate* isolate, Local<Object> object) override;
   Maybe<uint32_t> GetSharedArrayBufferId(
       Isolate* isolate, Local<SharedArrayBuffer> shared_array_buffer) override;
+  void* ReallocateBufferMemory(void* old_buffer,
+                               size_t old_length,
+                               size_t* new_length) override;
+  void FreeBufferMemory(void* buffer) override;
 
   static void SetTreatArrayBufferViewsAsHostObjects(
       const FunctionCallbackInfo<Value>& args);
@@ -61,6 +71,7 @@ class SerializerContext : public BaseObject,
 
  private:
   ValueSerializer serializer_;
+  size_t last_length_ = 0;
 };
 
 class DeserializerContext : public BaseObject,
@@ -144,6 +155,24 @@ Maybe<uint32_t> SerializerContext::GetSharedArrayBufferId(
   return id.ToLocalChecked()->Uint32Value(env()->context());
 }
 
+void* SerializerContext::ReallocateBufferMemory(void* old_buffer,
+                                                size_t requested_size,
+                                                size_t* new_length) {
+  *new_length = std::max(static_cast<size_t>(4096), requested_size);
+  if (old_buffer) {
+    void* ret = GetAllocator()->Reallocate(old_buffer, last_length_, *new_length);
+    last_length_ = *new_length;
+    return ret;
+  } else {
+    last_length_ = *new_length;
+    return GetAllocator()->Allocate(*new_length);
+  }
+}
+
+void SerializerContext::FreeBufferMemory(void* buffer) {
+  GetAllocator()->Free(buffer, last_length_);
+}
+
 Maybe<bool> SerializerContext::WriteHostObject(Isolate* isolate,
                                                Local<Object> input) {
   MaybeLocal<Value> ret;
@@ -209,9 +238,14 @@ void SerializerContext::ReleaseBuffer(const FunctionCallbackInfo<Value>& args) {
   // Note: Both ValueSerializer and this Buffer::New() variant use malloc()
   // as the underlying allocator.
   std::pair<uint8_t*, size_t> ret = ctx->serializer_.Release();
-  auto buf = Buffer::New(ctx->env(),
-                         reinterpret_cast<char*>(ret.first),
-                         ret.second);
+  std::unique_ptr<v8::BackingStore> bs =
+      v8::ArrayBuffer::NewBackingStore(reinterpret_cast<char*>(ret.first), ret.second,
+        [](void* data, size_t length, void* deleter_data) {
+          if (data) GetAllocator()->Free(reinterpret_cast<char*>(data), length);
+        }, nullptr);
+  Local<ArrayBuffer> ab = v8::ArrayBuffer::New(ctx->env()->isolate(), std::move(bs));
+
+  auto buf = Buffer::New(ctx->env(), ab, 0, ret.second);
 
   if (!buf.IsEmpty()) {
     args.GetReturnValue().Set(buf.ToLocalChecked());
