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// Copyright 2019 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 "testing/libfuzzer/fuzzers/mach/mach_message_converter.h"
#include <string.h>
#include <sys/types.h>
#include <utility>
#include "base/apple/mach_logging.h"
#include "base/containers/buffer_iterator.h"
#include "base/mac/scoped_mach_msg_destroy.h"
namespace mach_fuzzer {
namespace {
SendablePort ConvertPort(const MachPortType& port_proto) {
struct {
bool insert_send_right;
bool deallocate_receive_right;
mach_msg_type_name_t disposition;
} recipe;
switch (port_proto) {
case RECEIVE:
recipe = {true, false, MACH_MSG_TYPE_MOVE_RECEIVE};
break;
case SEND:
recipe = {false, false, MACH_MSG_TYPE_MAKE_SEND};
break;
case SEND_ONCE:
recipe = {false, false, MACH_MSG_TYPE_MAKE_SEND_ONCE};
break;
case DEAD_NAME:
recipe = {true, true, MACH_MSG_TYPE_COPY_SEND};
break;
case RECEIVE_NO_SENDERS:
recipe = {false, false, MACH_MSG_TYPE_MOVE_RECEIVE};
break;
}
SendablePort port;
kern_return_t kr = mach_port_allocate(
mach_task_self(), MACH_PORT_RIGHT_RECEIVE,
base::apple::ScopedMachReceiveRight::Receiver(port.receive_right).get());
MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_allocate";
port.name = port.receive_right.get();
port.disposition = recipe.disposition;
port.proto_type = port_proto;
if (recipe.insert_send_right) {
kr = mach_port_insert_right(mach_task_self(), port.name, port.name,
MACH_MSG_TYPE_MAKE_SEND);
MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_insert_right";
port.send_right.reset(port.name);
}
if (recipe.deallocate_receive_right) {
port.receive_right.reset();
}
return port;
}
bool ConvertDescriptor(base::BufferIterator<uint8_t>* iterator,
const Descriptor& descriptor_proto,
SendablePort* opt_port) {
switch (descriptor_proto.descriptor_oneof_case()) {
case Descriptor::kPort: {
auto* descriptor = iterator->MutableObject<mach_msg_port_descriptor_t>();
SendablePort port = ConvertPort(descriptor_proto.port());
descriptor->name = port.name;
descriptor->pad1 = 0;
descriptor->pad2 = 0;
descriptor->disposition = port.disposition;
descriptor->type = MACH_MSG_PORT_DESCRIPTOR;
*opt_port = std::move(port);
return true;
}
case Descriptor::kOol: {
auto* descriptor = iterator->MutableObject<mach_msg_ool_descriptor_t>();
descriptor->address =
const_cast<char*>(descriptor_proto.ool().data().data());
descriptor->size = descriptor_proto.ool().data().size();
descriptor->copy = MACH_MSG_VIRTUAL_COPY;
descriptor->pad1 = 0;
descriptor->type = MACH_MSG_OOL_DESCRIPTOR;
return true;
}
default:
return false;
}
}
} // namespace
SendableMessage ConvertProtoToMachMessage(const MachMessage& proto) {
SendableMessage message;
const size_t descriptor_count = proto.descriptors().size();
const size_t data_size = proto.data().size();
const bool include_body =
proto.include_body_if_not_complex() || descriptor_count > 0;
// This is the maximum size of the message. Depending on the descriptor type,
// the actual msgh_size may be less.
const size_t message_size =
sizeof(mach_msg_header_t) + (include_body ? sizeof(mach_msg_body_t) : 0) +
(sizeof(mach_msg_descriptor_t) * descriptor_count) + data_size;
message.buffer = std::make_unique<uint8_t[]>(round_msg(message_size));
base::BufferIterator<uint8_t> iterator(message.buffer.get(), message_size);
auto* header = iterator.MutableObject<mach_msg_header_t>();
message.header = header;
header->msgh_id = proto.id();
if (proto.has_local_port()) {
SendablePort port = ConvertPort(proto.local_port());
auto disposition = port.disposition;
// It's not legal to have a receive reply report.
if (disposition != MACH_MSG_TYPE_MOVE_RECEIVE) {
header->msgh_bits |= MACH_MSGH_BITS(0, disposition);
header->msgh_local_port = port.name;
message.ports.push_back(std::move(port));
}
}
if (include_body) {
auto* body = iterator.MutableObject<mach_msg_body_t>();
body->msgh_descriptor_count = descriptor_count;
}
if (descriptor_count > 0) {
header->msgh_bits |= MACH_MSGH_BITS_COMPLEX;
for (const auto& descriptor : proto.descriptors()) {
SendablePort opt_port;
if (!ConvertDescriptor(&iterator, descriptor, &opt_port)) {
return SendableMessage();
}
if (opt_port.name != MACH_PORT_NULL) {
message.ports.push_back(std::move(opt_port));
}
}
}
auto data = iterator.MutableSpan<uint8_t>(data_size);
memcpy(data.data(), proto.data().data(), proto.data().size());
header->msgh_size = round_msg(iterator.position());
return message;
}
SendResult SendMessage(mach_port_t remote_port, const MachMessage& proto) {
SendResult result;
result.message = ConvertProtoToMachMessage(proto);
if (!result.message.header) {
result.kr = KERN_FAILURE;
return result;
}
result.message.header->msgh_remote_port = remote_port;
result.message.header->msgh_bits |=
MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0);
base::ScopedMachMsgDestroy scoped_message(result.message.header);
result.kr = mach_msg(result.message.header, MACH_SEND_MSG | MACH_SEND_TIMEOUT,
result.message.header->msgh_size, 0, MACH_PORT_NULL,
/*timeout=*/0, MACH_PORT_NULL);
if (result.kr == KERN_SUCCESS) {
scoped_message.Disarm();
}
return result;
}
} // namespace mach_fuzzer
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