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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/core/ipcz_driver/wrapped_platform_handle.h"
#include <cstdint>
#include <utility>
#include "base/check.h"
#include "base/files/scoped_file.h"
#include "base/notreached.h"
#include "build/build_config.h"
#include "mojo/core/ipcz_driver/validate_enum.h"
#include "mojo/public/cpp/platform/platform_handle.h"
#include "third_party/ipcz/include/ipcz/ipcz.h"
#if BUILDFLAG(IS_FUCHSIA)
#include <lib/fdio/fd.h>
#include <lib/zx/handle.h>
#include "base/fuchsia/fuchsia_logging.h"
#endif
#if BUILDFLAG(IS_APPLE)
#include <mach/mach.h>
#include "base/apple/mach_logging.h"
#include "base/apple/scoped_mach_port.h"
#endif
namespace mojo::core::ipcz_driver {
namespace {
// Enumeration for different possible types of PlatformHandles that may be
// wrapped by a WrappedPlatformHandle.
enum class WrapperType : uint32_t {
// The wrapped PlatformHandle is transmissible as-is and can pass through a
// Transport unmodified.
kTransmissible,
#if BUILDFLAG(IS_FUCHSIA) || BUILDFLAG(IS_APPLE)
// The wrapped PlatformHandle is a file descriptor on Fuchsia or macOS/iOS,
// where the Transport can only transmit Fuchsia handles or Mach port rights,
// respectively.
//
// On Fuchsia we serialize this type of handle by replacing it with a handle
// to a corresponding fdio object. On macOS/iOS we replace it with a handle to
// a corresponding fileport send right. On the receiving end this deserializes
// back to a file descriptor.
kIndirectFileDescriptor,
#endif
// For ValidateEnum().
kMinValue = kTransmissible,
#if BUILDFLAG(IS_FUCHSIA) || BUILDFLAG(IS_APPLE)
kMaxValue = kIndirectFileDescriptor,
#else
kMaxValue = kTransmissible,
#endif
};
// Header for a serialized WrappedPlatformHandle object.
struct IPCZ_ALIGN(8) WrappedPlatformHandleHeader {
// The size of this structure in bytes.
uint32_t size;
// Indicates what specific type of handle is wrapped.
WrapperType type;
};
static_assert(sizeof(WrappedPlatformHandleHeader) == 8,
"Invalid WrappedPlatformHandleHeader size");
#if BUILDFLAG(IS_FUCHSIA)
PlatformHandle MakeFDTransmissible(base::ScopedFD fd) {
zx::handle result;
const zx_status_t status =
fdio_fd_transfer_or_clone(fd.release(), result.reset_and_get_address());
if (status != ZX_OK) {
ZX_DLOG(ERROR, status) << "fdio_fd_transfer_or_clone";
return {};
}
return PlatformHandle(std::move(result));
}
base::ScopedFD RecoverFDFromTransmissible(PlatformHandle handle) {
base::ScopedFD fd;
zx_status_t status = fdio_fd_create(handle.ReleaseHandle(),
base::ScopedFD::Receiver(fd).get());
if (status != ZX_OK) {
ZX_DLOG(ERROR, status) << "fdio_fd_create";
return {};
}
return fd;
}
#elif BUILDFLAG(IS_APPLE)
extern "C" {
kern_return_t fileport_makeport(int fd, mach_port_t*);
int fileport_makefd(mach_port_t);
} // extern "C"
PlatformHandle MakeFDTransmissible(base::ScopedFD fd) {
base::apple::ScopedMachSendRight port;
kern_return_t kr = fileport_makeport(
fd.get(), base::apple::ScopedMachSendRight::Receiver(port).get());
if (kr != KERN_SUCCESS) {
MACH_LOG(ERROR, kr) << "fileport_makeport";
return {};
}
return PlatformHandle(std::move(port));
}
base::ScopedFD RecoverFDFromTransmissible(PlatformHandle handle) {
if (!handle.is_mach_send()) {
return {};
}
return base::ScopedFD(fileport_makefd(handle.GetMachSendRight().get()));
}
#endif
} // namespace
WrappedPlatformHandle::WrappedPlatformHandle() = default;
WrappedPlatformHandle::WrappedPlatformHandle(PlatformHandle handle)
: handle_(std::move(handle)) {}
WrappedPlatformHandle::~WrappedPlatformHandle() = default;
void WrappedPlatformHandle::Close() {
handle_.reset();
}
bool WrappedPlatformHandle::IsSerializable() const {
return true;
}
bool WrappedPlatformHandle::GetSerializedDimensions(Transport& transmitter,
size_t& num_bytes,
size_t& num_handles) {
DCHECK(handle_.is_valid());
num_bytes = sizeof(WrappedPlatformHandleHeader);
num_handles = 1;
return true;
}
bool WrappedPlatformHandle::Serialize(Transport& transmitter,
base::span<uint8_t> data,
base::span<PlatformHandle> handles) {
DCHECK(handle_.is_valid());
DCHECK_EQ(sizeof(WrappedPlatformHandleHeader), data.size());
DCHECK_EQ(1u, handles.size());
PlatformHandle handle = std::move(handle_);
WrapperType type = WrapperType::kTransmissible;
#if BUILDFLAG(IS_FUCHSIA) || BUILDFLAG(IS_APPLE)
if (handle.is_fd()) {
type = WrapperType::kIndirectFileDescriptor;
handle = MakeFDTransmissible(handle.TakeFD());
}
#endif
auto& header = *reinterpret_cast<WrappedPlatformHandleHeader*>(data.data());
header.size = sizeof(header);
header.type = type;
handles[0] = std::move(handle);
return true;
}
// static
scoped_refptr<WrappedPlatformHandle> WrappedPlatformHandle::Deserialize(
base::span<const uint8_t> data,
base::span<PlatformHandle> handles) {
if (data.size() < sizeof(WrappedPlatformHandleHeader) ||
handles.size() != 1) {
return nullptr;
}
const auto& header =
*reinterpret_cast<const WrappedPlatformHandleHeader*>(data.data());
const size_t header_size = header.size;
if (header_size < sizeof(header) || header_size % 8 != 0) {
return nullptr;
}
if (!ValidateEnum(header.type)) {
return nullptr;
}
PlatformHandle handle = std::move(handles[0]);
switch (header.type) {
case WrapperType::kTransmissible:
break;
#if BUILDFLAG(IS_FUCHSIA) || BUILDFLAG(IS_APPLE)
case WrapperType::kIndirectFileDescriptor:
handle = PlatformHandle(RecoverFDFromTransmissible(std::move(handle)));
break;
#endif
default:
// Validated at head of function.
NOTREACHED();
}
if (!handle.is_valid()) {
return nullptr;
}
return base::MakeRefCounted<WrappedPlatformHandle>(std::move(handle));
}
} // namespace mojo::core::ipcz_driver
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