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Implement multiframe encryption correctly #1644

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merged 4 commits into from
Mar 25, 2021
Merged

Implement multiframe encryption correctly #1644

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bbf807d
Fix sending encrypted packets
joeygrover Mar 23, 2021
e21d198
Fix receiving encrypted multiframe packets
joeygrover Mar 23, 2021
fa9301e
Add PSM fix for already released Core versions
joeygrover Mar 23, 2021
385f314
Add back frame sequence rollover fix
joeygrover Mar 24, 2021
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119 changes: 76 additions & 43 deletions base/src/main/java/com/smartdevicelink/protocol/SdlProtocolBase.java
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,10 @@ public class SdlProtocolBase {
private final static String FailurePropagating_Msg = "Failure propagating ";

private static final int TLS_MAX_RECORD_SIZE = 16384;
private final static int TLS_RECORD_HEADER_SIZE = 5;
private final static int TLS_RECORD_MES_AUTH_CDE_SIZE = 32;
private final static int TLS_MAX_RECORD_PADDING_SIZE = 256;
private final static int TLS_MAX_DATA_TO_ENCRYPT_SIZE = TLS_MAX_RECORD_SIZE - TLS_RECORD_HEADER_SIZE - TLS_RECORD_MES_AUTH_CDE_SIZE - TLS_MAX_RECORD_PADDING_SIZE;

private static final int PRIMARY_TRANSPORT_ID = 1;
private static final int SECONDARY_TRANSPORT_ID = 2;
Expand Down Expand Up @@ -561,7 +565,8 @@ public void endSession(byte sessionID) {
public void sendMessage(ProtocolMessage protocolMsg) {
SessionType sessionType = protocolMsg.getSessionType();
byte sessionID = protocolMsg.getSessionID();

boolean requiresEncryption = protocolMsg.getPayloadProtected();
SdlSecurityBase sdlSec = null;
byte[] data;
if (protocolVersion.getMajor() > 1 && sessionType != SessionType.NAV && sessionType != SessionType.PCM) {
if (sessionType.eq(SessionType.CONTROL)) {
Expand Down Expand Up @@ -590,21 +595,15 @@ public void sendMessage(ProtocolMessage protocolMsg) {
data = protocolMsg.getData();
}

if (iSdlProtocol != null && protocolMsg.getPayloadProtected()) {

if (data != null && data.length > 0) {
byte[] dataToRead = new byte[TLS_MAX_RECORD_SIZE];
SdlSecurityBase sdlSec = iSdlProtocol.getSdlSecurity();
if (sdlSec == null)
return;

Integer iNumBytes = sdlSec.encryptData(data, dataToRead);
if ((iNumBytes == null) || (iNumBytes <= 0))
return;

byte[] encryptedData = new byte[iNumBytes];
System.arraycopy(dataToRead, 0, encryptedData, 0, iNumBytes);
data = encryptedData;
if (requiresEncryption) {
if (iSdlProtocol == null) {
DebugTool.logError(TAG, "Unable to encrypt packet, protocol callback was null");
return;
}
sdlSec = iSdlProtocol.getSdlSecurity();
if (sdlSec == null) {
DebugTool.logError(TAG, "Unable to encrypt packet, security library not found");
return;
}
}

Expand All @@ -616,24 +615,25 @@ public void sendMessage(ProtocolMessage protocolMsg) {
return;
}

synchronized (messageLock) {
if (data != null && data.length > getMtu(sessionType)) {
//Set the MTU according to session MTU provided by the IVI or the max data size for encryption if required
final Long mtu = requiresEncryption ? TLS_MAX_DATA_TO_ENCRYPT_SIZE : getMtu(sessionType);

synchronized (messageLock) {
if (data != null && data.length > mtu) {
//Since the packet is larger than the mtu size, it will be sent as a multi-frame packet
messageID++;

// Assemble first frame.
Long mtu = getMtu(sessionType);
int frameCount = Long.valueOf(data.length / mtu).intValue();
if (data.length % mtu > 0) {
frameCount++;
}
int frameCount = (int) Math.ceil(data.length / (double) mtu);

byte[] firstFrameData = new byte[8];
// First four bytes are data size.
System.arraycopy(BitConverter.intToByteArray(data.length), 0, firstFrameData, 0, 4);
// Second four bytes are frame count.
System.arraycopy(BitConverter.intToByteArray(frameCount), 0, firstFrameData, 4, 4);

SdlPacket firstHeader = SdlPacketFactory.createMultiSendDataFirst(sessionType, sessionID, messageID, (byte) protocolVersion.getMajor(), firstFrameData, protocolMsg.getPayloadProtected());
//NOTE: First frames cannot be encrypted because their payloads need to be exactly 8 bytes
SdlPacket firstHeader = SdlPacketFactory.createMultiSendDataFirst(sessionType, sessionID, messageID, (byte) protocolVersion.getMajor(), firstFrameData, false);
firstHeader.setPriorityCoefficient(1 + protocolMsg.priorityCoefficient);
firstHeader.setTransportRecord(activeTransports.get(sessionType));
//Send the first frame
Expand All @@ -642,33 +642,65 @@ public void sendMessage(ProtocolMessage protocolMsg) {
int currentOffset = 0;
byte frameSequenceNumber = 0;

byte[] dataBuffer, encryptedData;
for (int i = 0; i < frameCount; i++) {
if (i < (frameCount - 1)) {

frameSequenceNumber++;

if (frameSequenceNumber == SdlPacket.FRAME_INFO_FINAL_CONNESCUTIVE_FRAME) {
//If sequence numbers roll over to 0, increment again to avoid
//using the reserved sequence value for the final frame
++frameSequenceNumber;
if (frameSequenceNumber ==
SdlPacket.FRAME_INFO_FINAL_CONNESCUTIVE_FRAME) {
// we can't use 0x00 as frameSequenceNumber, because
// it's reserved for the last frame
++frameSequenceNumber;
}
} else {
}

if (i == frameCount - 1) {
frameSequenceNumber = SdlPacket.FRAME_INFO_FINAL_CONNESCUTIVE_FRAME;
} // end-if
}

int bytesToWrite = data.length - currentOffset;
if (bytesToWrite > mtu) {
bytesToWrite = mtu.intValue();
}
SdlPacket consecHeader = SdlPacketFactory.createMultiSendDataRest(sessionType, sessionID, bytesToWrite, frameSequenceNumber, messageID, (byte) protocolVersion.getMajor(), data, currentOffset, bytesToWrite, protocolMsg.getPayloadProtected());
consecHeader.setTransportRecord(activeTransports.get(sessionType));
consecHeader.setPriorityCoefficient(i + 2 + protocolMsg.priorityCoefficient);
handlePacketToSend(consecHeader);

SdlPacket consecutiveFrame;
if (requiresEncryption) {
//Retrieve a chunk of the data into a temporary buffer to be encrypted
dataBuffer = new byte[bytesToWrite];
System.arraycopy(data, currentOffset, dataBuffer, 0, bytesToWrite);

encryptedData = new byte[TLS_MAX_RECORD_SIZE];
Integer numberOfBytesEncrypted = sdlSec.encryptData(dataBuffer, encryptedData);
if (numberOfBytesEncrypted == null || (numberOfBytesEncrypted <= 0)) {
DebugTool.logError(TAG, "Unable to encrypt data");
return;
}

consecutiveFrame = SdlPacketFactory.createMultiSendDataRest(sessionType, sessionID, numberOfBytesEncrypted, frameSequenceNumber, messageID, (byte) protocolVersion.getMajor(), encryptedData, 0, numberOfBytesEncrypted, true);
} else {
consecutiveFrame = SdlPacketFactory.createMultiSendDataRest(sessionType, sessionID, bytesToWrite, frameSequenceNumber, messageID, (byte) protocolVersion.getMajor(), data, currentOffset, bytesToWrite, false);
}

consecutiveFrame.setTransportRecord(activeTransports.get(sessionType));
consecutiveFrame.setPriorityCoefficient(i + 2 + protocolMsg.priorityCoefficient);
handlePacketToSend(consecutiveFrame);
currentOffset += bytesToWrite;
}
} else {
messageID++;
if (requiresEncryption && data != null && data.length > 0) {
//Encrypt the data before sending
byte[] encryptedData = new byte[TLS_MAX_RECORD_SIZE];
Integer numberOfBytesEncrypted = sdlSec.encryptData(data, encryptedData);
if (numberOfBytesEncrypted == null || (numberOfBytesEncrypted <= 0)) {
DebugTool.logError(TAG, "Unable to encrypt data");
return;
}
//Put the encrypted bytes back into the data array
data = new byte[numberOfBytesEncrypted];
System.arraycopy(encryptedData, 0, data, 0, numberOfBytesEncrypted);
}
int dataLength = data != null ? data.length : 0;
SdlPacket header = SdlPacketFactory.createSingleSendData(sessionType, sessionID, dataLength, messageID, (byte) protocolVersion.getMajor(), data, protocolMsg.getPayloadProtected());
SdlPacket header = SdlPacketFactory.createSingleSendData(sessionType, sessionID, dataLength, messageID, (byte) protocolVersion.getMajor(), data, requiresEncryption);
header.setPriorityCoefficient(protocolMsg.priorityCoefficient);
header.setTransportRecord(activeTransports.get(sessionType));
handlePacketToSend(header);
Expand Down Expand Up @@ -1374,16 +1406,17 @@ protected void handleFrame(SdlPacket packet) {
if (packet.getPayload() != null && packet.getDataSize() > 0 && packet.isEncrypted()) {

SdlSecurityBase sdlSec = iSdlProtocol.getSdlSecurity();
byte[] dataToRead = new byte[4096];
byte[] dataToRead = new byte[TLS_MAX_RECORD_SIZE];

Integer iNumBytes = sdlSec.decryptData(packet.getPayload(), dataToRead);
if ((iNumBytes == null) || (iNumBytes <= 0)) {
Integer numberOfDecryptedBytes = sdlSec.decryptData(packet.getPayload(), dataToRead);
if ((numberOfDecryptedBytes == null) || (numberOfDecryptedBytes <= 0)) {
return;
}

byte[] decryptedData = new byte[iNumBytes];
System.arraycopy(dataToRead, 0, decryptedData, 0, iNumBytes);
byte[] decryptedData = new byte[numberOfDecryptedBytes];
System.arraycopy(dataToRead, 0, decryptedData, 0, numberOfDecryptedBytes);
packet.payload = decryptedData;
packet.dataSize = numberOfDecryptedBytes;
}

if (packet.getFrameType().equals(FrameType.Control)) {
Expand Down
13 changes: 8 additions & 5 deletions base/src/main/java/com/smartdevicelink/transport/SdlPsm.java
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Original file line number Diff line number Diff line change
Expand Up @@ -61,14 +61,14 @@ public class SdlPsm {
private static final byte FIRST_FRAME_DATA_SIZE = 0x08;

private static final int VERSION_MASK = 0xF0; //4 highest bits
private static final int COMPRESSION_MASK = 0x08; //4th lowest bit
private static final int ENCRYPTION_MASK = 0x08; //4th lowest bit
private static final int FRAME_TYPE_MASK = 0x07; //3 lowest bits


int state;

int version;
boolean compression;
boolean encrypted;
int frameType;
int serviceType;
int controlFrameInfo;
Expand Down Expand Up @@ -97,7 +97,7 @@ private int transitionOnInput(byte rawByte, int state) {
if (version == 0) { //It should never be 0
return ERROR_STATE;
}
compression = (1 == ((rawByte & (byte) COMPRESSION_MASK) >> 3));
encrypted = (1 == ((rawByte & (byte) ENCRYPTION_MASK) >> 3));


frameType = rawByte & (byte) FRAME_TYPE_MASK;
Expand Down Expand Up @@ -194,7 +194,10 @@ private int transitionOnInput(byte rawByte, int state) {
break;

case SdlPacket.FRAME_TYPE_FIRST:
if (dataLength == FIRST_FRAME_DATA_SIZE) {
if (dataLength == FIRST_FRAME_DATA_SIZE || this.encrypted) {
//In a few production releases of core the first frame could be
//encrypted. Therefore it is not an error state if the first frame data
//length is greater than 8 in that case alone.
break;
}
default:
Expand Down Expand Up @@ -263,7 +266,7 @@ private int transitionOnInput(byte rawByte, int state) {
public SdlPacket getFormedPacket() {
if (state == FINISHED_STATE) {
//Log.trace(TAG, "Finished packet.");
return new SdlPacket(version, compression, frameType,
return new SdlPacket(version, encrypted, frameType,
serviceType, controlFrameInfo, sessionId,
dataLength, messageId, payload);
} else {
Expand Down