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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.
#include "base/apple/mach_port_rendezvous.h"
#include <mach/mig.h>
#include <unistd.h>
#include <utility>
#include "base/apple/foundation_util.h"
#include "base/apple/mach_logging.h"
#include "base/bits.h"
#include "base/compiler_specific.h"
#include "base/containers/buffer_iterator.h"
#include "base/feature_list.h"
#include "base/logging.h"
#include "base/mac/scoped_mach_msg_destroy.h"
#include "base/no_destructor.h"
#include "base/notreached.h"
#include "base/numerics/byte_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/types/cxx23_to_underlying.h"
namespace base {
namespace {
size_t CalculateResponseSize(size_t num_ports, size_t additional_data_length) {
return bits::AlignUp(
sizeof(mach_msg_base_t) +
(num_ports * sizeof(mach_msg_port_descriptor_t)) +
(num_ports * sizeof(MachPortsForRendezvous::key_type)) +
sizeof(uint64_t) + additional_data_length,
sizeof(uint32_t));
}
} // namespace
MachRendezvousPort::MachRendezvousPort(mach_port_t name,
mach_msg_type_name_t disposition)
: name_(name), disposition_(disposition) {
DCHECK(disposition == MACH_MSG_TYPE_MOVE_RECEIVE ||
disposition == MACH_MSG_TYPE_MOVE_SEND ||
disposition == MACH_MSG_TYPE_MOVE_SEND_ONCE ||
disposition == MACH_MSG_TYPE_COPY_SEND ||
disposition == MACH_MSG_TYPE_MAKE_SEND ||
disposition == MACH_MSG_TYPE_MAKE_SEND_ONCE);
}
MachRendezvousPort::MachRendezvousPort(apple::ScopedMachSendRight send_right)
: name_(send_right.release()), disposition_(MACH_MSG_TYPE_MOVE_SEND) {}
MachRendezvousPort::MachRendezvousPort(
apple::ScopedMachReceiveRight receive_right)
: name_(receive_right.release()),
disposition_(MACH_MSG_TYPE_MOVE_RECEIVE) {}
MachRendezvousPort::~MachRendezvousPort() = default;
void MachRendezvousPort::Destroy() {
// Map the disposition to the type of right to deallocate.
mach_port_right_t right = 0;
switch (disposition_) {
case 0:
DCHECK(name_ == MACH_PORT_NULL);
return;
case MACH_MSG_TYPE_COPY_SEND:
case MACH_MSG_TYPE_MAKE_SEND:
case MACH_MSG_TYPE_MAKE_SEND_ONCE:
// Right is not owned, would be created by transit.
return;
case MACH_MSG_TYPE_MOVE_RECEIVE:
right = MACH_PORT_RIGHT_RECEIVE;
break;
case MACH_MSG_TYPE_MOVE_SEND:
right = MACH_PORT_RIGHT_SEND;
break;
case MACH_MSG_TYPE_MOVE_SEND_ONCE:
right = MACH_PORT_RIGHT_SEND_ONCE;
break;
default:
NOTREACHED() << "Leaking port name " << name_ << " with disposition "
<< disposition_;
}
kern_return_t kr = mach_port_mod_refs(mach_task_self(), name_, right, -1);
MACH_DCHECK(kr == KERN_SUCCESS, kr)
<< "Failed to drop ref on port name " << name_;
name_ = MACH_PORT_NULL;
disposition_ = 0;
}
MachPortRendezvousServerBase::MachPortRendezvousServerBase() = default;
MachPortRendezvousServerBase::~MachPortRendezvousServerBase() = default;
void MachPortRendezvousServerBase::HandleRequest() {
// Receive the request message, using the kernel audit token to ascertain the
// PID of the sender.
struct : mach_msg_header_t {
mach_msg_audit_trailer_t trailer;
} request{};
request.msgh_size = sizeof(request);
request.msgh_local_port = server_port_.get();
const mach_msg_option_t options =
MACH_RCV_MSG | MACH_RCV_TIMEOUT |
MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT);
mach_msg_return_t mr = mach_msg(&request, options, 0, sizeof(request),
server_port_.get(), 0, MACH_PORT_NULL);
if (mr != KERN_SUCCESS) {
MACH_LOG(ERROR, mr) << "mach_msg receive";
return;
}
// Destroy the message in case of an early return, which will release
// any rights from a bad message. In the case of a disallowed sender,
// the destruction of the reply port will break them out of a mach_msg.
ScopedMachMsgDestroy scoped_message(&request);
if ((request.msgh_id != internal::kMachRendezvousMsgIdRequest &&
!IsValidAdditionalMessageId(request.msgh_id)) ||
request.msgh_size != sizeof(mach_msg_header_t)) {
// Do not reply to messages that are unexpected.
return;
}
std::optional<MachPortsForRendezvous> ports_to_send =
PortsForClient(request.trailer.msgh_audit);
if (!ports_to_send) {
return;
}
std::vector<uint8_t> additional_data =
AdditionalDataForReply(request.msgh_id);
std::unique_ptr<uint8_t[]> response = CreateReplyMessage(
request.msgh_remote_port, *ports_to_send, std::move(additional_data));
auto* header = reinterpret_cast<mach_msg_header_t*>(response.get());
mr = mach_msg(header, MACH_SEND_MSG, header->msgh_size, 0, MACH_PORT_NULL,
MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
if (mr == KERN_SUCCESS) {
scoped_message.Disarm();
} else {
MACH_LOG(ERROR, mr) << "mach_msg send";
}
}
std::unique_ptr<uint8_t[]> MachPortRendezvousServerBase::CreateReplyMessage(
mach_port_t reply_port,
const MachPortsForRendezvous& ports,
std::vector<uint8_t> additional_data) {
const size_t port_count = ports.size();
const size_t buffer_size =
CalculateResponseSize(port_count, additional_data.size());
auto buffer = std::make_unique<uint8_t[]>(buffer_size);
auto iterator =
UNSAFE_TODO(BufferIterator<uint8_t>(buffer.get(), buffer_size));
auto* message = iterator.MutableObject<mach_msg_base_t>();
message->header.msgh_bits =
MACH_MSGH_BITS_REMOTE(MACH_MSG_TYPE_MOVE_SEND_ONCE) |
MACH_MSGH_BITS_COMPLEX;
message->header.msgh_size = checked_cast<mach_msg_size_t>(buffer_size);
message->header.msgh_remote_port = reply_port;
message->header.msgh_id = internal::kMachRendezvousMsgIdResponse;
message->body.msgh_descriptor_count =
checked_cast<mach_msg_size_t>(port_count);
auto descriptors =
iterator.MutableSpan<mach_msg_port_descriptor_t>(port_count);
auto port_identifiers =
iterator.MutableSpan<MachPortsForRendezvous::key_type>(port_count);
auto port_it = ports.begin();
for (size_t i = 0; i < port_count; ++i, ++port_it) {
const MachRendezvousPort& port_for_rendezvous = port_it->second;
mach_msg_port_descriptor_t* descriptor = &descriptors[i];
descriptor->name = port_for_rendezvous.name();
descriptor->disposition = port_for_rendezvous.disposition();
descriptor->type = MACH_MSG_PORT_DESCRIPTOR;
port_identifiers[i] = port_it->first;
}
// The current iterator location may not have appropriate alignment to
// directly store a uint64_t. Write the size as bytes instead.
iterator.MutableSpan<uint8_t, 8>()->copy_from(
base::U64ToNativeEndian(additional_data.size()));
iterator.MutableSpan<uint8_t>(additional_data.size())
.copy_from(additional_data);
return buffer;
}
MachPortRendezvousClient::MachPortRendezvousClient() = default;
MachPortRendezvousClient::~MachPortRendezvousClient() = default;
apple::ScopedMachSendRight MachPortRendezvousClient::TakeSendRight(
MachPortsForRendezvous::key_type key) {
MachRendezvousPort port = PortForKey(key);
DCHECK(port.disposition() == 0 ||
port.disposition() == MACH_MSG_TYPE_PORT_SEND ||
port.disposition() == MACH_MSG_TYPE_PORT_SEND_ONCE);
return apple::ScopedMachSendRight(port.name());
}
apple::ScopedMachReceiveRight MachPortRendezvousClient::TakeReceiveRight(
MachPortsForRendezvous::key_type key) {
MachRendezvousPort port = PortForKey(key);
DCHECK(port.disposition() == 0 ||
port.disposition() == MACH_MSG_TYPE_PORT_RECEIVE);
return apple::ScopedMachReceiveRight(port.name());
}
size_t MachPortRendezvousClient::GetPortCount() {
AutoLock lock(lock_);
return ports_.size();
}
bool MachPortRendezvousClient::SendRequest(
apple::ScopedMachSendRight server_port,
mach_msg_id_t request_msg_id,
size_t additional_response_data_size) {
const size_t buffer_size =
CalculateResponseSize(internal::kMaximumRendezvousPorts,
additional_response_data_size) +
sizeof(mach_msg_audit_trailer_t);
auto buffer = std::make_unique<uint8_t[]>(buffer_size);
auto iterator =
UNSAFE_TODO(BufferIterator<uint8_t>(buffer.get(), buffer_size));
// Perform a send and receive mach_msg.
auto* message = iterator.MutableObject<mach_msg_base_t>();
message->header.msgh_bits =
MACH_MSGH_BITS(MACH_MSG_TYPE_MOVE_SEND, MACH_MSG_TYPE_MAKE_SEND_ONCE);
// The |buffer_size| is used for receiving, since it includes space for the
// the entire reply and receiving trailer. But for the request being sent,
// the size is just an empty message.
message->header.msgh_size = sizeof(mach_msg_header_t);
message->header.msgh_remote_port = server_port.release();
message->header.msgh_local_port = mig_get_reply_port();
message->header.msgh_id = request_msg_id;
const mach_msg_option_t options =
MACH_SEND_MSG | MACH_RCV_MSG |
MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT);
kern_return_t mr = mach_msg(
&message->header, options, message->header.msgh_size,
checked_cast<mach_msg_size_t>(buffer_size),
message->header.msgh_local_port, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
if (mr != KERN_SUCCESS) {
MACH_LOG(ERROR, mr) << "mach_msg";
return false;
}
if (message->header.msgh_id != internal::kMachRendezvousMsgIdResponse) {
// Check if the response contains a rendezvous reply. If there were no
// ports for this client, then the send right would have been destroyed.
if (message->header.msgh_id == MACH_NOTIFY_SEND_ONCE) {
return true;
}
return false;
}
if (!ValidateMessage(message, iterator)) {
return false;
}
const size_t port_count = message->body.msgh_descriptor_count;
auto descriptors = iterator.Span<mach_msg_port_descriptor_t>(port_count);
auto port_identifiers =
iterator.Span<MachPortsForRendezvous::key_type>(port_count);
if (descriptors.size() != port_identifiers.size()) {
// Ensure that the descriptors and keys are of the same size.
return false;
}
for (size_t i = 0; i < port_count; ++i) {
MachRendezvousPort rendezvous_port(descriptors[i].name,
descriptors[i].disposition);
ports_.emplace(port_identifiers[i], rendezvous_port);
}
return true;
}
MachRendezvousPort MachPortRendezvousClient::PortForKey(
MachPortsForRendezvous::key_type key) {
AutoLock lock(lock_);
auto it = ports_.find(key);
MachRendezvousPort port;
if (it != ports_.end()) {
port = it->second;
ports_.erase(it);
}
return port;
}
} // namespace base
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