SecureSessionMgr.cpp

/*
 *
 *    Copyright (c) 2020-2021 Project CHIP Authors
 *    Copyright (c) 2013-2017 Nest Labs, Inc.
 *    All rights reserved.
 *
 *    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.
 */

/**
 *    @file
 *      This file implements the CHIP Connection object that maintains a UDP connection.
 *      TODO This class should be extended to support TCP as well...
 *
 */

#include "SecureSessionMgr.h"

#include <inttypes.h>
#include <string.h>

#include <app/util/basic-types.h>
#include <core/CHIPKeyIds.h>
#include <platform/CHIPDeviceLayer.h>
#include <protocols/secure_channel/Constants.h>
#include <support/CodeUtils.h>
#include <support/SafeInt.h>
#include <support/logging/CHIPLogging.h>
#include <transport/AdminPairingTable.h>
#include <transport/SecureMessageCodec.h>
#include <transport/TransportMgr.h>

#include <inttypes.h>

namespace chip {

using System::PacketBufferHandle;
using Transport::PeerAddress;
using Transport::PeerConnectionState;

uint32_t EncryptedPacketBufferHandle::GetMsgId() const
{
    PacketHeader header;
    uint16_t headerSize = 0;
    CHIP_ERROR err      = header.Decode((*this)->Start(), (*this)->DataLength(), &headerSize);

    if (err == CHIP_NO_ERROR)
    {
        return header.GetMessageId();
    }

    ChipLogError(Inet, "Failed to decode EncryptedPacketBufferHandle header with error: %s", ErrorStr(err));

    return 0;
}

SecureSessionMgr::SecureSessionMgr() : mState(State::kNotReady) {}

SecureSessionMgr::~SecureSessionMgr()
{
    CancelExpiryTimer();
}

CHIP_ERROR SecureSessionMgr::Init(NodeId localNodeId, System::Layer * systemLayer, TransportMgrBase * transportMgr,
                                  Transport::AdminPairingTable * admins,
                                  Transport::MessageCounterManagerInterface * messageCounterManager)
{
    VerifyOrReturnError(mState == State::kNotReady, CHIP_ERROR_INCORRECT_STATE);
    VerifyOrReturnError(transportMgr != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

    mState                 = State::kInitialized;
    mLocalNodeId           = localNodeId;
    mSystemLayer           = systemLayer;
    mTransportMgr          = transportMgr;
    mAdmins                = admins;
    mMessageCounterManager = messageCounterManager;

    mGlobalEncryptedMessageCounter.Init();

    ChipLogProgress(Inet, "local node id is 0x" ChipLogFormatX64, ChipLogValueX64(mLocalNodeId));

    ScheduleExpiryTimer();

    mTransportMgr->SetSecureSessionMgr(this);

    return CHIP_NO_ERROR;
}

void SecureSessionMgr::Shutdown()
{
    CancelExpiryTimer();

    mMessageCounterManager = nullptr;

    mState        = State::kNotReady;
    mLocalNodeId  = kUndefinedNodeId;
    mSystemLayer  = nullptr;
    mTransportMgr = nullptr;
    mAdmins       = nullptr;
    mCB           = nullptr;
}

Transport::Type SecureSessionMgr::GetTransportType(NodeId peerNodeId)
{
    PeerConnectionState * state = mPeerConnections.FindPeerConnectionState(peerNodeId, nullptr);

    if (state)
    {
        return state->GetPeerAddress().GetTransportType();
    }

    return Transport::Type::kUndefined;
}

CHIP_ERROR SecureSessionMgr::SendMessage(SecureSessionHandle session, PayloadHeader & payloadHeader,
                                         System::PacketBufferHandle && msgBuf, EncryptedPacketBufferHandle * bufferRetainSlot)
{
    PacketHeader unusedPacketHeader;
    return SendMessage(session, payloadHeader, unusedPacketHeader, std::move(msgBuf), bufferRetainSlot,
                       EncryptionState::kPayloadIsUnencrypted);
}

CHIP_ERROR SecureSessionMgr::SendEncryptedMessage(SecureSessionHandle session, EncryptedPacketBufferHandle && msgBuf,
                                                  EncryptedPacketBufferHandle * bufferRetainSlot)
{
    VerifyOrReturnError(!msgBuf.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);
    VerifyOrReturnError(!msgBuf.HasChainedBuffer(), CHIP_ERROR_INVALID_MESSAGE_LENGTH);

    // Our send path needs a (writable) PacketBuffer (e.g. so it can encode a
    // PacketHeader into it), so get that from the EncryptedPacketBufferHandle.
    System::PacketBufferHandle mutableBuf(std::move(msgBuf).CastToWritable());

    // Advancing the start to encrypted header, since SendMessage will attach the packet header on top of it.
    PacketHeader packetHeader;
    ReturnErrorOnFailure(packetHeader.DecodeAndConsume(mutableBuf));

    PayloadHeader payloadHeader;
    return SendMessage(session, payloadHeader, packetHeader, std::move(mutableBuf), bufferRetainSlot,
                       EncryptionState::kPayloadIsEncrypted);
}

CHIP_ERROR SecureSessionMgr::SendMessage(SecureSessionHandle session, PayloadHeader & payloadHeader, PacketHeader & packetHeader,
                                         System::PacketBufferHandle && msgBuf, EncryptedPacketBufferHandle * bufferRetainSlot,
                                         EncryptionState encryptionState)
{
    CHIP_ERROR err              = CHIP_NO_ERROR;
    PeerConnectionState * state = nullptr;
    NodeId localNodeId          = mLocalNodeId;

    Transport::AdminPairingInfo * admin = nullptr;

    VerifyOrExit(mState == State::kInitialized, err = CHIP_ERROR_INCORRECT_STATE);
    VerifyOrExit(!msgBuf.IsNull(), err = CHIP_ERROR_INVALID_ARGUMENT);
    VerifyOrExit(!msgBuf->HasChainedBuffer(), err = CHIP_ERROR_INVALID_MESSAGE_LENGTH);

    // Find an active connection to the specified peer node
    state = GetPeerConnectionState(session);
    VerifyOrExit(state != nullptr, err = CHIP_ERROR_NOT_CONNECTED);

    // This marks any connection where we send data to as 'active'
    mPeerConnections.MarkConnectionActive(state);
    admin = mAdmins->FindAdminWithId(state->GetAdminId());
    VerifyOrExit(admin != nullptr, err = CHIP_ERROR_INCORRECT_STATE);
    localNodeId = admin->GetNodeId();

    if (IsControlMessage(payloadHeader))
    {
        packetHeader.SetSecureSessionControlMsg(true);
    }

    if (encryptionState == EncryptionState::kPayloadIsUnencrypted)
    {
        MessageCounter & counter = GetSendCounterForPacket(payloadHeader, *state);
        err                      = SecureMessageCodec::Encode(localNodeId, state, payloadHeader, packetHeader, msgBuf, counter);
        SuccessOrExit(err);
    }

    err = packetHeader.EncodeBeforeData(msgBuf);
    SuccessOrExit(err);

    // Retain the packet buffer in case it's needed for retransmissions.
    if (bufferRetainSlot != nullptr)
    {
        *bufferRetainSlot = EncryptedPacketBufferHandle::MarkEncrypted(msgBuf.Retain());
    }

    ChipLogProgress(Inet, "Sending msg from 0x" ChipLogFormatX64 " to 0x" ChipLogFormatX64 " at utc time: %" PRId64 " msec",
                    ChipLogValueX64(localNodeId), ChipLogValueX64(state->GetPeerNodeId()), System::Layer::GetClock_MonotonicMS());

    if (state->GetTransport() != nullptr)
    {
        ChipLogProgress(Inet, "Sending secure msg on connection specific transport");
        err = state->GetTransport()->SendMessage(state->GetPeerAddress(), std::move(msgBuf));
    }
    else if (mTransportMgr != nullptr)
    {
        ChipLogProgress(Inet, "Sending secure msg on generic transport");
        err = mTransportMgr->SendMessage(state->GetPeerAddress(), std::move(msgBuf));
    }
    else
    {
        ChipLogError(Inet, "The transport manager is not initialized. Unable to send the message");
        err = CHIP_ERROR_INCORRECT_STATE;
    }
    ChipLogProgress(Inet, "Secure msg send status %s", ErrorStr(err));
    SuccessOrExit(err);

exit:
    if (!msgBuf.IsNull())
    {
        const char * errStr = ErrorStr(err);
        if (state == nullptr)
        {
            ChipLogError(Inet, "Secure transport could not find a valid PeerConnection: %s", errStr);
        }
    }

    return err;
}

CHIP_ERROR SecureSessionMgr::NewPairing(const Optional<Transport::PeerAddress> & peerAddr, NodeId peerNodeId,
                                        PairingSession * pairing, SecureSession::SessionRole direction, Transport::AdminId admin,
                                        Transport::Base * transport)
{
    uint16_t peerKeyId          = pairing->GetPeerKeyId();
    uint16_t localKeyId         = pairing->GetLocalKeyId();
    PeerConnectionState * state = mPeerConnections.FindPeerConnectionState(Optional<NodeId>::Value(peerNodeId), peerKeyId, nullptr);

    // Find any existing connection with the same node and key ID
    if (state && (state->GetAdminId() == Transport::kUndefinedAdminId || state->GetAdminId() == admin))
    {
        mPeerConnections.MarkConnectionExpired(
            state, [this](const Transport::PeerConnectionState & state1) { HandleConnectionExpired(state1); });
    }

    ChipLogDetail(Inet, "New pairing for device 0x%08" PRIx32 "%08" PRIx32 ", key %d!!", static_cast<uint32_t>(peerNodeId >> 32),
                  static_cast<uint32_t>(peerNodeId), peerKeyId);
    state = nullptr;
    ReturnErrorOnFailure(
        mPeerConnections.CreateNewPeerConnectionState(Optional<NodeId>::Value(peerNodeId), peerKeyId, localKeyId, &state));
    ReturnErrorCodeIf(state == nullptr, CHIP_ERROR_NO_MEMORY);

    state->SetAdminId(admin);
    state->SetTransport(transport);

    if (peerAddr.HasValue() && peerAddr.Value().GetIPAddress() != Inet::IPAddress::Any)
    {
        state->SetPeerAddress(peerAddr.Value());
    }
    else if (peerAddr.HasValue() && peerAddr.Value().GetTransportType() == Transport::Type::kBle)
    {
        state->SetPeerAddress(peerAddr.Value());
    }
    else if (peerAddr.HasValue() &&
             (peerAddr.Value().GetTransportType() == Transport::Type::kTcp ||
              peerAddr.Value().GetTransportType() == Transport::Type::kUdp))
    {
        return CHIP_ERROR_INVALID_ARGUMENT;
    }

    ReturnErrorOnFailure(pairing->DeriveSecureSession(state->GetSecureSession(), direction));

    if (mCB != nullptr)
    {
        state->GetSessionMessageCounter().GetPeerMessageCounter().SetCounter(pairing->GetPeerCounter());
        mCB->OnNewConnection({ state->GetPeerNodeId(), state->GetPeerKeyID(), admin }, this);
    }

    return CHIP_NO_ERROR;
}

void SecureSessionMgr::ScheduleExpiryTimer()
{
    CHIP_ERROR err =
        mSystemLayer->StartTimer(CHIP_PEER_CONNECTION_TIMEOUT_CHECK_FREQUENCY_MS, SecureSessionMgr::ExpiryTimerCallback, this);

    VerifyOrDie(err == CHIP_NO_ERROR);
}

void SecureSessionMgr::CancelExpiryTimer()
{
    if (mSystemLayer != nullptr)
    {
        mSystemLayer->CancelTimer(SecureSessionMgr::ExpiryTimerCallback, this);
    }
}

void SecureSessionMgr::OnMessageReceived(const PeerAddress & peerAddress, System::PacketBufferHandle && msg)
{
    PacketHeader packetHeader;

    ReturnOnFailure(packetHeader.DecodeAndConsume(msg));

    if (packetHeader.GetFlags().Has(Header::FlagValues::kSecure))
    {
        SecureMessageDispatch(packetHeader, peerAddress, std::move(msg));
    }
    else
    {
        MessageDispatch(packetHeader, peerAddress, std::move(msg));
    }
}

void SecureSessionMgr::MessageDispatch(const PacketHeader & packetHeader, const Transport::PeerAddress & peerAddress,
                                       System::PacketBufferHandle && msg)
{
    if (mCB != nullptr)
    {
        PayloadHeader payloadHeader;
        ReturnOnFailure(payloadHeader.DecodeAndConsume(msg));
        mCB->OnMessageReceived(packetHeader, payloadHeader, SecureSessionHandle(), peerAddress, std::move(msg), this);
    }
}

void SecureSessionMgr::SecureMessageDispatch(const PacketHeader & packetHeader, const Transport::PeerAddress & peerAddress,
                                             System::PacketBufferHandle && msg)
{
    CHIP_ERROR err = CHIP_NO_ERROR;

    PeerConnectionState * state = mPeerConnections.FindPeerConnectionState(packetHeader.GetEncryptionKeyID(), nullptr);

    PayloadHeader payloadHeader;

    Transport::AdminPairingInfo * admin = nullptr;

    bool modifiedAdmin = false;
    NodeId localNodeId;
    FabricId fabricId;

    VerifyOrExit(!msg.IsNull(), ChipLogError(Inet, "Secure transport received NULL packet, discarding"));

    if (state == nullptr)
    {
        ChipLogError(Inet, "Data received on an unknown connection (%d). Dropping it!!", packetHeader.GetEncryptionKeyID());
        ExitNow(err = CHIP_ERROR_KEY_NOT_FOUND_FROM_PEER);
    }

    // Verify message counter
    if (packetHeader.GetFlags().Has(Header::FlagValues::kSecureSessionControlMessage))
    {
        // TODO: control message counter is not implemented yet
    }
    else
    {
        if (!state->GetSessionMessageCounter().GetPeerMessageCounter().IsSynchronized())
        {
            // Queue and start message sync procedure
            err = mMessageCounterManager->QueueReceivedMessageAndStartSync(
                packetHeader, { state->GetPeerNodeId(), state->GetPeerKeyID(), state->GetAdminId() }, state, peerAddress,
                std::move(msg));

            if (err != CHIP_NO_ERROR)
            {
                ChipLogError(Inet,
                             "Message counter synchronization for received message, failed to "
                             "QueueReceivedMessageAndStartSync, err = %" PRId32,
                             err);
            }
            else
            {
                ChipLogDetail(Inet, "Received message have been queued due to peer counter is not synced");
            }

            return;
        }

        err = state->GetSessionMessageCounter().GetPeerMessageCounter().Verify(packetHeader.GetMessageId());
        if (err != CHIP_NO_ERROR)
        {
            ChipLogError(Inet, "Message counter verify failed, err = %" PRId32, err);
        }
        SuccessOrExit(err);
    }

    admin = mAdmins->FindAdminWithId(state->GetAdminId());
    VerifyOrExit(admin != nullptr,
                 ChipLogError(Inet, "Secure transport received packet for unknown admin (%p, %d) pairing, discarding", state,
                              state->GetAdminId()));
    if (packetHeader.GetDestinationNodeId().HasValue() && admin->GetNodeId() != kUndefinedNodeId)
    {
        VerifyOrExit(admin->GetNodeId() == packetHeader.GetDestinationNodeId().Value(),
                     ChipLogError(Inet,
                                  "Secure transport received message, but destination node ID (0x" ChipLogFormatX64
                                  ") doesn't match our node ID (0x" ChipLogFormatX64 "), discarding",
                                  ChipLogValueX64(packetHeader.GetDestinationNodeId().Value()),
                                  ChipLogValueX64(admin->GetNodeId())));
    }

    if (packetHeader.GetDestinationNodeId().HasValue())
    {
        ChipLogProgress(Inet, "Secure transport received message destined to fabric %d, node 0x" ChipLogFormatX64 ". Key ID %d",
                        static_cast<int>(state->GetAdminId()), ChipLogValueX64(packetHeader.GetDestinationNodeId().Value()),
                        packetHeader.GetEncryptionKeyID());
    }
    else
    {
        ChipLogProgress(Inet, "Secure transport received message for fabric %d without node ID. Key ID %d",
                        static_cast<int>(state->GetAdminId()), packetHeader.GetEncryptionKeyID());
    }

    mPeerConnections.MarkConnectionActive(state);

    // Decode the message
    VerifyOrExit(CHIP_NO_ERROR == SecureMessageCodec::Decode(state, payloadHeader, packetHeader, msg),
                 ChipLogError(Inet, "Secure transport received message, but failed to decode it, discarding"));

    if (packetHeader.GetFlags().Has(Header::FlagValues::kSecureSessionControlMessage))
    {
        // TODO: control message counter is not implemented yet
    }
    else
    {
        state->GetSessionMessageCounter().GetPeerMessageCounter().Commit(packetHeader.GetMessageId());
    }

    // See operational-credentials-server.cpp for explanation as to why fabricId is being set to commissioner node id
    // This is temporary code until AddOptCert is implemented through which an admin will be correctly added with the correct
    // fields.
    // TODO: Remove temporary code once AddOptCert is implemented
    if (packetHeader.GetSourceNodeId().HasValue())
    {
        if (state->GetPeerNodeId() == kUndefinedNodeId)
        {
            state->SetPeerNodeId(packetHeader.GetSourceNodeId().Value());
        }
    }

    // TODO: Remove temporary code once AddOptCert is implemented
    if (packetHeader.GetDestinationNodeId().HasValue())
    {
        localNodeId = packetHeader.GetDestinationNodeId().Value();
        if (localNodeId != kUndefinedNodeId && admin->GetNodeId() != localNodeId)
        {
            admin->SetNodeId(localNodeId);
            ChipLogProgress(Inet, "Setting nodeID %" PRIX64 " on admin.", admin->GetNodeId());
            modifiedAdmin = true;
        }
    }

    // TODO: Remove temporary code once AddOptCert is implemented
    if (packetHeader.GetSourceNodeId().HasValue())
    {
        fabricId = packetHeader.GetSourceNodeId().Value();
        if (fabricId != kUndefinedFabricId && admin->GetFabricId() != fabricId)
        {
            admin->SetFabricId(packetHeader.GetSourceNodeId().Value());
            ChipLogProgress(Inet, "Setting fabricID %" PRIX64 " on admin.", admin->GetFabricId());
            modifiedAdmin = true;
        }
    }

    // TODO: Remove temporary code once AddOptCert is implemented
    if (modifiedAdmin)
    {
        ChipLogProgress(Inet, "Since admin was modified, persisting changes to KVS");
        mAdmins->Store(admin->GetAdminId());
    }

    // TODO: once mDNS address resolution is available reconsider if this is required
    // This updates the peer address once a packet is received from a new address
    // and serves as a way to auto-detect peer changing IPs.
    if (state->GetPeerAddress() != peerAddress)
    {
        state->SetPeerAddress(peerAddress);
    }

    if (mCB != nullptr)
    {
        SecureSessionHandle session(state->GetPeerNodeId(), state->GetPeerKeyID(), state->GetAdminId());
        mCB->OnMessageReceived(packetHeader, payloadHeader, session, peerAddress, std::move(msg), this);
    }

exit:
    if (err != CHIP_NO_ERROR && mCB != nullptr)
    {
        mCB->OnReceiveError(err, peerAddress, this);
    }
}

void SecureSessionMgr::HandleConnectionExpired(const Transport::PeerConnectionState & state)
{
    char addr[Transport::PeerAddress::kMaxToStringSize];
    state.GetPeerAddress().ToString(addr);

    ChipLogDetail(Inet, "Connection from '%s' expired", addr);

    if (mCB != nullptr)
    {
        mCB->OnConnectionExpired({ state.GetPeerNodeId(), state.GetPeerKeyID(), state.GetAdminId() }, this);
    }

    mTransportMgr->Disconnect(state.GetPeerAddress());
}

void SecureSessionMgr::ExpiryTimerCallback(System::Layer * layer, void * param, System::Error error)
{
    SecureSessionMgr * mgr = reinterpret_cast<SecureSessionMgr *>(param);
#if CHIP_CONFIG_SESSION_REKEYING
    // TODO(#2279): session expiration is currently disabled until rekeying is supported
    // the #ifdef should be removed after that.
    mgr->mPeerConnections.ExpireInactiveConnections(
        CHIP_PEER_CONNECTION_TIMEOUT_MS,
        [this](const Transport::PeerConnectionState & state1) { HandleConnectionExpired(state1); });
#endif
    mgr->ScheduleExpiryTimer(); // re-schedule the oneshot timer
}

PeerConnectionState * SecureSessionMgr::GetPeerConnectionState(SecureSessionHandle session)
{
    return mPeerConnections.FindPeerConnectionState(Optional<NodeId>::Value(session.mPeerNodeId), session.mPeerKeyId, nullptr);
}

} // namespace chip