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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "gin/array_buffer.h"
#include <stddef.h>
#include <stdlib.h>
#include "base/bits.h"
#include "base/check_op.h"
#include "base/no_destructor.h"
#include "build/build_config.h"
#include "gin/per_isolate_data.h"
#include "partition_alloc/page_allocator.h"
#include "partition_alloc/partition_alloc.h"
#include "partition_alloc/partition_root.h"
#include "v8/include/v8-initialization.h"
#if BUILDFLAG(IS_POSIX)
#include <sys/mman.h>
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif // BUILDFLAG(IS_POSIX)
namespace gin {
// ArrayBufferAllocator -------------------------------------------------------
partition_alloc::PartitionRoot* ArrayBufferAllocator::partition_ = nullptr;
void* ArrayBufferAllocator::Allocate(size_t length) {
constexpr partition_alloc::AllocFlags flags =
partition_alloc::AllocFlags::kZeroFill |
partition_alloc::AllocFlags::kReturnNull;
return AllocateInternal<flags>(length);
}
void* ArrayBufferAllocator::AllocateUninitialized(size_t length) {
constexpr partition_alloc::AllocFlags flags =
partition_alloc::AllocFlags::kReturnNull;
return AllocateInternal<flags>(length);
}
template <partition_alloc::AllocFlags flags>
void* ArrayBufferAllocator::AllocateInternal(size_t length) {
#ifdef V8_ENABLE_SANDBOX
// The V8 sandbox requires all ArrayBuffer backing stores to be allocated
// inside the sandbox address space. This isn't guaranteed if allocation
// override hooks (which are e.g. used by GWP-ASan) are enabled or if a
// memory tool (e.g. ASan) overrides malloc, so disable both.
constexpr auto new_flags = flags |
partition_alloc::AllocFlags::kNoOverrideHooks |
partition_alloc::AllocFlags::kNoMemoryToolOverride;
#else
constexpr auto new_flags = flags;
#endif
return partition_->AllocInline<new_flags>(length,
"gin::ArrayBufferAllocator");
}
void ArrayBufferAllocator::Free(void* data, size_t length) {
#ifdef V8_ENABLE_SANDBOX
// See |AllocateMemoryWithFlags|.
partition_->Free<partition_alloc::FreeFlags::kNoMemoryToolOverride>(data);
#else
partition_->Free(data);
#endif
}
// static
ArrayBufferAllocator* ArrayBufferAllocator::SharedInstance() {
static ArrayBufferAllocator* instance = new ArrayBufferAllocator();
return instance;
}
// static
void ArrayBufferAllocator::InitializePartition() {
partition_alloc::PartitionOptions opts;
opts.backup_ref_ptr = partition_alloc::PartitionOptions::kDisabled;
opts.use_configurable_pool = partition_alloc::PartitionOptions::kAllowed;
static base::NoDestructor<partition_alloc::PartitionAllocator>
partition_allocator(opts);
partition_ = partition_allocator->root();
}
// ArrayBuffer ----------------------------------------------------------------
ArrayBuffer::ArrayBuffer() = default;
ArrayBuffer::ArrayBuffer(v8::Isolate* isolate, v8::Local<v8::ArrayBuffer> array)
: backing_store_(array->GetBackingStore()) {}
ArrayBuffer::~ArrayBuffer() = default;
ArrayBuffer& ArrayBuffer::operator=(const ArrayBuffer& other) = default;
// Converter<ArrayBuffer> -----------------------------------------------------
bool Converter<ArrayBuffer>::FromV8(v8::Isolate* isolate,
v8::Local<v8::Value> val,
ArrayBuffer* out) {
if (!val->IsArrayBuffer())
return false;
*out = ArrayBuffer(isolate, v8::Local<v8::ArrayBuffer>::Cast(val));
return true;
}
// ArrayBufferView ------------------------------------------------------------
ArrayBufferView::ArrayBufferView()
: offset_(0),
num_bytes_(0) {
}
ArrayBufferView::ArrayBufferView(v8::Isolate* isolate,
v8::Local<v8::ArrayBufferView> view)
: array_buffer_(isolate, view->Buffer()),
offset_(view->ByteOffset()),
num_bytes_(view->ByteLength()) {
}
ArrayBufferView::~ArrayBufferView() = default;
ArrayBufferView& ArrayBufferView::operator=(const ArrayBufferView& other) =
default;
// Converter<ArrayBufferView> -------------------------------------------------
bool Converter<ArrayBufferView>::FromV8(v8::Isolate* isolate,
v8::Local<v8::Value> val,
ArrayBufferView* out) {
if (!val->IsArrayBufferView())
return false;
*out = ArrayBufferView(isolate, v8::Local<v8::ArrayBufferView>::Cast(val));
return true;
}
// ArrayBufferSharedMemoryMapper ---------------------------------------------
namespace {
#ifdef V8_ENABLE_SANDBOX
// When the V8 sandbox is enabled, shared memory backing ArrayBuffers must be
// mapped into the sandbox address space. This custom SharedMemoryMapper
// implements this.
class ArrayBufferSharedMemoryMapper : public base::SharedMemoryMapper {
public:
std::optional<base::span<uint8_t>> Map(
base::subtle::PlatformSharedMemoryHandle handle,
bool write_allowed,
uint64_t offset,
size_t size) override {
v8::VirtualAddressSpace* address_space = v8::V8::GetSandboxAddressSpace();
size_t allocation_granularity = address_space->allocation_granularity();
v8::PlatformSharedMemoryHandle v8_handle;
#if BUILDFLAG(IS_APPLE)
v8_handle = v8::SharedMemoryHandleFromMachMemoryEntry(handle);
#elif BUILDFLAG(IS_FUCHSIA)
v8_handle = v8::SharedMemoryHandleFromVMO(handle->get());
#elif BUILDFLAG(IS_WIN)
v8_handle = v8::SharedMemoryHandleFromFileMapping(handle);
#elif BUILDFLAG(IS_ANDROID)
v8_handle = v8::SharedMemoryHandleFromFileDescriptor(handle);
#elif BUILDFLAG(IS_POSIX)
v8_handle = v8::SharedMemoryHandleFromFileDescriptor(handle.fd);
#else
#error "Unknown platform"
#endif
// Size and offset must be a multiple of the page allocation granularity.
// The caller already ensures that the offset is a multiple of the
// allocation granularity though.
CHECK_EQ(0UL, offset % allocation_granularity);
size_t mapping_size = base::bits::AlignUp(size, allocation_granularity);
v8::PagePermissions permissions = write_allowed
? v8::PagePermissions::kReadWrite
: v8::PagePermissions::kRead;
uintptr_t mapping = v8::V8::GetSandboxAddressSpace()->AllocateSharedPages(
0, mapping_size, permissions, v8_handle, offset);
if (!mapping)
return std::nullopt;
return base::span(reinterpret_cast<uint8_t*>(mapping), size);
}
void Unmap(base::span<uint8_t> mapping) override {
v8::VirtualAddressSpace* address_space = v8::V8::GetSandboxAddressSpace();
size_t allocation_granularity = address_space->allocation_granularity();
uintptr_t address = reinterpret_cast<uintptr_t>(mapping.data());
CHECK_EQ(0UL, address % allocation_granularity);
size_t mapping_size =
base::bits::AlignUp(mapping.size(), allocation_granularity);
address_space->FreeSharedPages(address, mapping_size);
}
};
#endif // V8_ENABLE_SANDBOX
} // namespace
base::SharedMemoryMapper* GetSharedMemoryMapperForArrayBuffers() {
#if V8_ENABLE_SANDBOX
static ArrayBufferSharedMemoryMapper instance;
return &instance;
#else
return base::SharedMemoryMapper::GetDefaultInstance();
#endif
}
} // namespace gin
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