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/******************************************************************************
*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
#pragma once
#include <array>
#include <chrono>
#include <condition_variable>
#include <mutex>
#include <optional>
#include <queue>
#include <thread>
#include <variant>
#include "common/bind.h"
#include "crypto_toolbox/crypto_toolbox.h"
#include "hci/hci_packets.h"
#include "hci/le_security_interface.h"
#include "packet/packet_view.h"
#include "security/ecdh_keys.h"
#include "security/initial_informations.h"
#include "security/pairing_failure.h"
#include "security/smp_packets.h"
#include "security/ui.h"
// Code generated by PDL does not allow us ot do || and && operations on bits
// efficiently. Use those masks on fields requiring them until this is solved
constexpr uint8_t AuthReqMaskBondingFlag = 0x01;
constexpr uint8_t AuthReqMaskMitm = 0x04;
constexpr uint8_t AuthReqMaskSc = 0x08;
constexpr uint8_t AuthReqMaskKeypress = 0x10;
constexpr uint8_t AuthReqMaskCt2 = 0x20;
constexpr uint8_t KeyMaskEnc = 0x01;
constexpr uint8_t KeyMaskId = 0x02;
constexpr uint8_t KeyMaskSign = 0x04;
constexpr uint8_t KeyMaskLink = 0x08;
using bluetooth::hci::EncryptionChangeView;
using bluetooth::hci::EncryptionKeyRefreshCompleteView;
namespace bluetooth {
namespace security {
using crypto_toolbox::Octet16;
/* This class represents an event send from other subsystems into SMP Pairing Handler,
* i.e. user request from the UI, L2CAP or HCI interaction */
class PairingEvent {
public:
enum TYPE { EXIT, L2CAP, HCI_EVENT, UI };
TYPE type;
std::optional<CommandView> l2cap_packet;
std::optional<hci::EventView> hci_event;
enum UI_ACTION_TYPE { PAIRING_ACCEPTED, CONFIRM_YESNO, PASSKEY };
UI_ACTION_TYPE ui_action;
uint32_t ui_value;
PairingEvent(TYPE type) : type(type) {}
PairingEvent(CommandView l2cap_packet) : type(L2CAP), l2cap_packet(l2cap_packet) {}
PairingEvent(UI_ACTION_TYPE ui_action, uint32_t ui_value) : type(UI), ui_action(ui_action), ui_value(ui_value) {}
PairingEvent(hci::EventView hci_event) : type(HCI_EVENT), hci_event(hci_event) {}
};
constexpr int SMP_TIMEOUT = 30;
using CommandViewOrFailure = std::variant<CommandView, PairingFailure>;
using Phase1Result = std::pair<PairingRequestView /* pairning_request*/, PairingResponseView /* pairing_response */>;
using Phase1ResultOrFailure = std::variant<PairingFailure, Phase1Result>;
using KeyExchangeResult =
std::tuple<EcdhPublicKey /* PKa */, EcdhPublicKey /* PKb */, std::array<uint8_t, 32> /*dhkey*/>;
using Stage1Result = std::tuple<Octet16, Octet16, Octet16, Octet16>;
using Stage1ResultOrFailure = std::variant<PairingFailure, Stage1Result>;
using Stage2ResultOrFailure = std::variant<PairingFailure, Octet16 /* LTK */>;
using DistributedKeysOrFailure = std::variant<PairingFailure, DistributedKeys, std::monostate>;
using LegacyStage1Result = Octet16 /*TK*/;
using LegacyStage1ResultOrFailure = std::variant<PairingFailure, LegacyStage1Result>;
using StkOrFailure = std::variant<PairingFailure, Octet16 /* STK */>;
/* PairingHandlerLe takes care of the Pairing process. Pairing is strictly defined
* exchange of messages and UI interactions, divided into PHASES.
*
* Each PairingHandlerLe have a thread executing |PairingMain| method. Thread is
* blocked when waiting for UI/L2CAP/HCI interactions, and moves through all the
* phases.
*/
class PairingHandlerLe {
public:
// This is the phase of pairing as defined in BT Spec (with exception of
// accept prompt)
// * ACCEPT_PROMPT - we're waiting for the user to accept remotely initiated pairing
// * PHASE1 - feature exchange
// * PHASE2 - authentication
// * PHASE3 - key exchange
enum PAIRING_PHASE { ACCEPT_PROMPT, PHASE1, PHASE2, PHASE3 };
PAIRING_PHASE phase;
// All the knowledge to initiate the pairing process must be passed into this function
PairingHandlerLe(PAIRING_PHASE phase, InitialInformations informations)
: phase(phase), queue_guard(), thread_(&PairingHandlerLe::PairingMain, this, informations) {}
~PairingHandlerLe() {
SendExitSignal();
// we need ot check if thread is joinable, because tests call join form
// within WaitUntilPairingFinished
if (thread_.joinable()) thread_.join();
}
void PairingMain(InitialInformations i);
Phase1ResultOrFailure ExchangePairingFeature(const InitialInformations& i);
void SendL2capPacket(const InitialInformations& i, std::unique_ptr<bluetooth::security::CommandBuilder> command) {
i.proper_l2cap_interface->Enqueue(std::move(command), i.l2cap_handler);
}
void SendHciLeStartEncryption(const InitialInformations& i, uint16_t conn_handle, const std::array<uint8_t, 8>& rand,
const uint16_t& ediv, const Octet16& ltk) {
i.le_security_interface->EnqueueCommand(hci::LeStartEncryptionBuilder::Create(conn_handle, rand, ediv, ltk),
i.l2cap_handler->BindOnce([](hci::CommandStatusView) {
// TODO: handle command status. It's important - can show we are not
// connected any more.
// TODO: if anything useful must be done there, use some sort of proper
// handler, wait/notify, and execute on the handler thread
}));
}
void SendHciLeLongTermKeyReply(const InitialInformations& i, uint16_t conn_handle, const Octet16& ltk) {
i.le_security_interface->EnqueueCommand(
hci::LeLongTermKeyRequestReplyBuilder::Create(conn_handle, ltk),
i.l2cap_handler->BindOnce([](hci::CommandCompleteView) {}));
}
std::variant<PairingFailure, EncryptionChangeView, EncryptionKeyRefreshCompleteView> WaitEncryptionChanged() {
PairingEvent e = WaitForEvent();
if (e.type != PairingEvent::HCI_EVENT) return PairingFailure("Was expecting HCI event but received something else");
if (!e.hci_event->IsValid()) return PairingFailure("Received invalid HCI event");
if (e.hci_event->GetEventCode() == hci::EventCode::ENCRYPTION_CHANGE) {
EncryptionChangeView enc_chg_packet = EncryptionChangeView::Create(*e.hci_event);
if (!enc_chg_packet.IsValid()) {
return PairingFailure("Invalid Encryption Change packet received");
}
return enc_chg_packet;
}
if (e.hci_event->GetEventCode() == hci::EventCode::ENCRYPTION_KEY_REFRESH_COMPLETE) {
hci::EncryptionKeyRefreshCompleteView enc_packet = EncryptionKeyRefreshCompleteView::Create(*e.hci_event);
if (!enc_packet.IsValid()) {
return PairingFailure("Invalid Key Refresh packet received");
}
return enc_packet;
}
return PairingFailure("Was expecting Encryption Change or Key Refresh Complete but received something else");
}
std::variant<PairingFailure, hci::LeLongTermKeyRequestView> WaitLeLongTermKeyRequest() {
PairingEvent e = WaitForEvent();
if (e.type != PairingEvent::HCI_EVENT) return PairingFailure("Was expecting HCI event but received something else");
if (!e.hci_event->IsValid()) return PairingFailure("Received invalid HCI event");
if (e.hci_event->GetEventCode() != hci::EventCode::LE_META_EVENT) return PairingFailure("Was expecting LE event");
hci::LeMetaEventView le_event = hci::LeMetaEventView::Create(*e.hci_event);
if (!le_event.IsValid()) {
return PairingFailure("Invalid LE Event received");
}
if (le_event.GetSubeventCode() != hci::SubeventCode::LONG_TERM_KEY_REQUEST) {
return PairingFailure("Was expecting Long Term Key Request");
}
hci::LeLongTermKeyRequestView ltk_req_packet = hci::LeLongTermKeyRequestView::Create(le_event);
if (!ltk_req_packet.IsValid()) {
return PairingFailure("Invalid LE Long Term Key Request received");
}
return ltk_req_packet;
}
inline bool IAmCentral(const InitialInformations& i) {
return i.my_role == hci::Role::CENTRAL;
}
/* This function generates data that should be passed to remote device, except
the private key. */
static MyOobData GenerateOobData();
std::variant<PairingFailure, KeyExchangeResult> ExchangePublicKeys(const InitialInformations& i,
OobDataFlag remote_have_oob_data);
Stage1ResultOrFailure DoSecureConnectionsStage1(const InitialInformations& i, const EcdhPublicKey& PKa,
const EcdhPublicKey& PKb, const PairingRequestView& pairing_request,
const PairingResponseView& pairing_response);
Stage1ResultOrFailure SecureConnectionsNumericComparison(const InitialInformations& i, const EcdhPublicKey& PKa,
const EcdhPublicKey& PKb);
Stage1ResultOrFailure SecureConnectionsJustWorks(const InitialInformations& i, const EcdhPublicKey& PKa,
const EcdhPublicKey& PKb);
Stage1ResultOrFailure SecureConnectionsPasskeyEntry(const InitialInformations& i, const EcdhPublicKey& PKa,
const EcdhPublicKey& PKb, IoCapability my_iocaps,
IoCapability remote_iocaps);
Stage1ResultOrFailure SecureConnectionsOutOfBand(const InitialInformations& i, const EcdhPublicKey& Pka,
const EcdhPublicKey& Pkb, OobDataFlag my_oob_flag,
OobDataFlag remote_oob_flag);
Stage2ResultOrFailure DoSecureConnectionsStage2(const InitialInformations& i, const EcdhPublicKey& PKa,
const EcdhPublicKey& PKb, const PairingRequestView& pairing_request,
const PairingResponseView& pairing_response,
const Stage1Result stage1result,
const std::array<uint8_t, 32>& dhkey);
DistributedKeysOrFailure DistributeKeys(const InitialInformations& i, const PairingResponseView& pairing_response,
bool isSecureConnections);
DistributedKeysOrFailure ReceiveKeys(const uint8_t& keys_i_receive);
LegacyStage1ResultOrFailure DoLegacyStage1(const InitialInformations& i, const PairingRequestView& pairing_request,
const PairingResponseView& pairing_response);
LegacyStage1ResultOrFailure LegacyOutOfBand(const InitialInformations& i);
LegacyStage1ResultOrFailure LegacyJustWorks();
LegacyStage1ResultOrFailure LegacyPasskeyEntry(const InitialInformations& i, const IoCapability& my_iocaps,
const IoCapability& remote_iocaps);
StkOrFailure DoLegacyStage2(const InitialInformations& i, const PairingRequestView& pairing_request,
const PairingResponseView& pairing_response, const Octet16& tk);
void SendKeys(const InitialInformations& i, const uint8_t& keys_i_send, Octet16 ltk, uint16_t ediv,
std::array<uint8_t, 8> rand, Octet16 irk, Address identity_address, AddrType identity_addres_type,
Octet16 signature_key);
/* This can be called from any thread to immediately finish the pairing in progress. */
void SendExitSignal() {
{
std::unique_lock<std::mutex> lock(queue_guard);
queue.push(PairingEvent(PairingEvent::EXIT));
}
pairing_thread_blocker_.notify_one();
}
/* SMP Command received from remote device */
void OnCommandView(CommandView packet) {
{
std::unique_lock<std::mutex> lock(queue_guard);
queue.push(PairingEvent(std::move(packet)));
}
pairing_thread_blocker_.notify_one();
}
/* SMP Command received from remote device */
void OnHciEvent(hci::EventView hci_event) {
{
std::unique_lock<std::mutex> lock(queue_guard);
queue.push(PairingEvent(std::move(hci_event)));
}
pairing_thread_blocker_.notify_one();
}
/* Interaction from user */
void OnUiAction(PairingEvent::UI_ACTION_TYPE ui_action, uint32_t ui_value) {
{
std::unique_lock<std::mutex> lock(queue_guard);
queue.push(PairingEvent(ui_action, ui_value));
}
pairing_thread_blocker_.notify_one();
}
/* HCI LE event received from remote device */
void OnHciLeEvent(hci::LeMetaEventView hci_event) {
{
std::unique_lock<std::mutex> lock(queue_guard);
queue.push(PairingEvent(std::move(hci_event)));
}
pairing_thread_blocker_.notify_one();
}
/* Blocks the pairing process until some external interaction, or timeout happens */
PairingEvent WaitForEvent() {
std::unique_lock<std::mutex> lock(queue_guard);
do {
if (!queue.empty()) {
PairingEvent e = queue.front();
queue.pop();
return e;
}
// This releases the lock while blocking.
if (pairing_thread_blocker_.wait_for(lock, std::chrono::seconds(SMP_TIMEOUT)) == std::cv_status::timeout) {
return PairingEvent(PairingEvent::EXIT);
}
} while (true);
}
std::optional<PairingEvent> WaitUiPairingAccept() {
PairingEvent e = WaitForEvent();
if (e.type == PairingEvent::UI & e.ui_action == PairingEvent::PAIRING_ACCEPTED) {
return e;
} else {
return std::nullopt;
}
}
std::optional<PairingEvent> WaitUiConfirmYesNo() {
PairingEvent e = WaitForEvent();
if (e.type == PairingEvent::UI & e.ui_action == PairingEvent::CONFIRM_YESNO) {
return e;
} else {
return std::nullopt;
}
}
std::optional<PairingEvent> WaitUiPasskey() {
PairingEvent e = WaitForEvent();
// It's possible to receive PAIRING_CONFIRM from remote device while waiting for the passkey.
// Store it until it's needed.
if (e.type == PairingEvent::L2CAP) {
auto l2cap_packet = e.l2cap_packet.value();
if (!l2cap_packet.IsValid()) {
LOG_WARN("Malformed L2CAP packet received!");
return std::nullopt;
}
const auto& received_code = l2cap_packet.GetCode();
if (received_code != Code::PAIRING_CONFIRM) {
LOG_WARN("Was waiting for passkey, received bad packet instead!");
return std::nullopt;
}
auto pkt = PairingConfirmView::Create(l2cap_packet);
if (!pkt.IsValid()) {
LOG_WARN("Malformed PAIRING_CONFIRM packet");
return std::nullopt;
}
cached_pariring_confirm_view = std::make_unique<PairingConfirmView>(pkt);
e = WaitForEvent();
}
if (e.type == PairingEvent::UI & e.ui_action == PairingEvent::PASSKEY) {
return e;
} else {
return std::nullopt;
}
}
template <Code C>
struct CodeToPacketView;
template <>
struct CodeToPacketView<Code::PAIRING_REQUEST> {
typedef PairingRequestView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_RESPONSE> {
typedef PairingResponseView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_CONFIRM> {
typedef PairingConfirmView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_RANDOM> {
typedef PairingRandomView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_FAILED> {
typedef PairingFailedView type;
};
template <>
struct CodeToPacketView<Code::ENCRYPTION_INFORMATION> {
typedef EncryptionInformationView type;
};
template <>
struct CodeToPacketView<Code::CENTRAL_IDENTIFICATION> {
typedef CentralIdentificationView type;
};
template <>
struct CodeToPacketView<Code::IDENTITY_INFORMATION> {
typedef IdentityInformationView type;
};
template <>
struct CodeToPacketView<Code::IDENTITY_ADDRESS_INFORMATION> {
typedef IdentityAddressInformationView type;
};
template <>
struct CodeToPacketView<Code::SIGNING_INFORMATION> {
typedef SigningInformationView type;
};
template <>
struct CodeToPacketView<Code::SECURITY_REQUEST> {
typedef SecurityRequestView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_PUBLIC_KEY> {
typedef PairingPublicKeyView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_DH_KEY_CHECK> {
typedef PairingDhKeyCheckView type;
};
template <>
struct CodeToPacketView<Code::PAIRING_KEYPRESS_NOTIFICATION> {
typedef PairingKeypressNotificationView type;
};
template <Code CODE>
std::variant<typename CodeToPacketView<CODE>::type, PairingFailure> WaitPacket() {
PairingEvent e = WaitForEvent();
switch (e.type) {
case PairingEvent::EXIT:
return PairingFailure(
/*FROM_HERE,*/ "Was expecting L2CAP Packet " + CodeText(CODE) + ", but received EXIT instead");
case PairingEvent::HCI_EVENT:
return PairingFailure(
/*FROM_HERE,*/ "Was expecting L2CAP Packet " + CodeText(CODE) + ", but received HCI_EVENT instead");
case PairingEvent::UI:
return PairingFailure(
/*FROM_HERE,*/ "Was expecting L2CAP Packet " + CodeText(CODE) + ", but received UI instead");
case PairingEvent::L2CAP: {
auto l2cap_packet = e.l2cap_packet.value();
if (!l2cap_packet.IsValid()) {
return PairingFailure("Malformed L2CAP packet received!");
}
const auto& received_code = l2cap_packet.GetCode();
if (received_code != CODE) {
if (received_code == Code::PAIRING_FAILED) {
auto pkt = PairingFailedView::Create(l2cap_packet);
if (!pkt.IsValid()) return PairingFailure("Malformed " + CodeText(CODE) + " packet");
return PairingFailure(/*FROM_HERE,*/
"Was expecting " + CodeText(CODE) + ", but received PAIRING_FAILED instead",
pkt.GetReason());
}
return PairingFailure(/*FROM_HERE,*/
"Was expecting " + CodeText(CODE) + ", but received " + CodeText(received_code) +
" instead",
received_code);
}
auto pkt = CodeToPacketView<CODE>::type::Create(l2cap_packet);
if (!pkt.IsValid()) return PairingFailure("Malformed " + CodeText(CODE) + " packet");
return pkt;
}
}
}
auto WaitPairingRequest() {
return WaitPacket<Code::PAIRING_REQUEST>();
}
auto WaitPairingResponse() {
return WaitPacket<Code::PAIRING_RESPONSE>();
}
std::variant<bluetooth::security::PairingConfirmView, bluetooth::security::PairingFailure> WaitPairingConfirm() {
if (cached_pariring_confirm_view) {
PairingConfirmView pkt = *cached_pariring_confirm_view;
cached_pariring_confirm_view.release();
return pkt;
}
return WaitPacket<Code::PAIRING_CONFIRM>();
}
auto WaitPairingRandom() {
return WaitPacket<Code::PAIRING_RANDOM>();
}
auto WaitPairingPublicKey() {
return WaitPacket<Code::PAIRING_PUBLIC_KEY>();
}
auto WaitPairingDHKeyCheck() {
return WaitPacket<Code::PAIRING_DH_KEY_CHECK>();
}
auto WaitEncryptionInformationRequest() {
return WaitPacket<Code::ENCRYPTION_INFORMATION>();
}
auto WaitEncryptionInformation() {
return WaitPacket<Code::ENCRYPTION_INFORMATION>();
}
auto WaitCentralIdentification() {
return WaitPacket<Code::CENTRAL_IDENTIFICATION>();
}
auto WaitIdentityInformation() {
return WaitPacket<Code::IDENTITY_INFORMATION>();
}
auto WaitIdentityAddressInformation() {
return WaitPacket<Code::IDENTITY_ADDRESS_INFORMATION>();
}
auto WaitSigningInformation() {
return WaitPacket<Code::SIGNING_INFORMATION>();
}
/* This is just for test, never use in production code! */
void WaitUntilPairingFinished() {
thread_.join();
}
private:
std::condition_variable pairing_thread_blocker_;
std::mutex queue_guard;
std::queue<PairingEvent> queue;
std::thread thread_;
// holds pairing_confirm, if received out of order
std::unique_ptr<PairingConfirmView> cached_pariring_confirm_view;
};
} // namespace security
} // namespace bluetooth