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ladybird/Userland/Libraries/LibTLS/ClientHandshake.cpp

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/*
* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/Endian.h>
#include <AK/Random.h>
#include <LibCore/Timer.h>
#include <LibCrypto/ASN1/DER.h>
#include <LibCrypto/PK/Code/EMSA_PSS.h>
#include <LibTLS/TLSv12.h>
namespace TLS {
ssize_t TLSv12::handle_server_hello_done(ReadonlyBytes buffer)
{
if (buffer.size() < 3)
return (i8)Error::NeedMoreData;
size_t size = buffer[0] * 0x10000 + buffer[1] * 0x100 + buffer[2];
if (buffer.size() - 3 < size)
return (i8)Error::NeedMoreData;
return size + 3;
}
ssize_t TLSv12::handle_hello(ReadonlyBytes buffer, WritePacketStage& write_packets)
{
write_packets = WritePacketStage::Initial;
if (m_context.connection_status != ConnectionStatus::Disconnected && m_context.connection_status != ConnectionStatus::Renegotiating) {
dbgln("unexpected hello message");
return (i8)Error::UnexpectedMessage;
}
ssize_t res = 0;
size_t min_hello_size = 41;
if (min_hello_size > buffer.size()) {
dbgln("need more data");
return (i8)Error::NeedMoreData;
}
size_t following_bytes = buffer[0] * 0x10000 + buffer[1] * 0x100 + buffer[2];
res += 3;
if (buffer.size() - res < following_bytes) {
dbgln("not enough data after header: {} < {}", buffer.size() - res, following_bytes);
return (i8)Error::NeedMoreData;
}
if (buffer.size() - res < 2) {
dbgln("not enough data for version");
return (i8)Error::NeedMoreData;
}
auto version = (Version)AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
res += 2;
if (!supports_version(version))
return (i8)Error::NotSafe;
memcpy(m_context.remote_random, buffer.offset_pointer(res), sizeof(m_context.remote_random));
res += sizeof(m_context.remote_random);
u8 session_length = buffer[res++];
if (buffer.size() - res < session_length) {
dbgln("not enough data for session id");
return (i8)Error::NeedMoreData;
}
if (session_length && session_length <= 32) {
memcpy(m_context.session_id, buffer.offset_pointer(res), session_length);
m_context.session_id_size = session_length;
#if TLS_DEBUG
dbgln("Remote session ID:");
print_buffer(ReadonlyBytes { m_context.session_id, session_length });
#endif
} else {
m_context.session_id_size = 0;
}
res += session_length;
if (buffer.size() - res < 2) {
dbgln("not enough data for cipher suite listing");
return (i8)Error::NeedMoreData;
}
auto cipher = (CipherSuite)AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
res += 2;
if (!supports_cipher(cipher)) {
m_context.cipher = CipherSuite::Invalid;
dbgln("No supported cipher could be agreed upon");
return (i8)Error::NoCommonCipher;
}
m_context.cipher = cipher;
dbgln_if(TLS_DEBUG, "Cipher: {}", (u16)cipher);
// The handshake hash function is _always_ SHA256
m_context.handshake_hash.initialize(Crypto::Hash::HashKind::SHA256);
// Compression method
if (buffer.size() - res < 1)
return (i8)Error::NeedMoreData;
u8 compression = buffer[res++];
if (compression != 0)
return (i8)Error::CompressionNotSupported;
if (m_context.connection_status != ConnectionStatus::Renegotiating)
m_context.connection_status = ConnectionStatus::Negotiating;
if (m_context.is_server) {
dbgln("unsupported: server mode");
write_packets = WritePacketStage::ServerHandshake;
}
// Presence of extensions is determined by availability of bytes after compression_method
if (buffer.size() - res >= 2) {
auto extensions_bytes_total = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
dbgln_if(TLS_DEBUG, "Extensions bytes total: {}", extensions_bytes_total);
}
while (buffer.size() - res >= 4) {
auto extension_type = (HandshakeExtension)AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
res += 2;
u16 extension_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
res += 2;
dbgln_if(TLS_DEBUG, "Extension {} with length {}", (u16)extension_type, extension_length);
if (buffer.size() - res < extension_length)
return (i8)Error::NeedMoreData;
if (extension_type == HandshakeExtension::ServerName) {
// RFC6066 section 3: SNI extension_data can be empty in the server hello
if (extension_length > 0) {
// ServerNameList total size
if (buffer.size() - res < 2)
return (i8)Error::NeedMoreData;
auto sni_name_list_bytes = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
dbgln_if(TLS_DEBUG, "SNI: expecting ServerNameList of {} bytes", sni_name_list_bytes);
// Exactly one ServerName should be present
if (buffer.size() - res < 3)
return (i8)Error::NeedMoreData;
auto sni_name_type = (NameType)(*(const u8*)buffer.offset_pointer(res++));
auto sni_name_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
if (sni_name_type != NameType::HostName)
return (i8)Error::NotUnderstood;
if (sizeof(sni_name_type) + sizeof(sni_name_length) + sni_name_length != sni_name_list_bytes)
return (i8)Error::BrokenPacket;
// Read out the host_name
if (buffer.size() - res < sni_name_length)
return (i8)Error::NeedMoreData;
m_context.extensions.SNI = String { (const char*)buffer.offset_pointer(res), sni_name_length };
res += sni_name_length;
dbgln("SNI host_name: {}", m_context.extensions.SNI);
}
} else if (extension_type == HandshakeExtension::ApplicationLayerProtocolNegotiation && m_context.alpn.size()) {
if (buffer.size() - res > 2) {
auto alpn_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
if (alpn_length && alpn_length <= extension_length - 2) {
const u8* alpn = buffer.offset_pointer(res + 2);
size_t alpn_position = 0;
while (alpn_position < alpn_length) {
u8 alpn_size = alpn[alpn_position++];
if (alpn_size + alpn_position >= extension_length)
break;
String alpn_str { (const char*)alpn + alpn_position, alpn_length };
if (alpn_size && m_context.alpn.contains_slow(alpn_str)) {
m_context.negotiated_alpn = alpn_str;
dbgln("negotiated alpn: {}", alpn_str);
break;
}
alpn_position += alpn_length;
if (!m_context.is_server) // server hello must contain one ALPN
break;
}
}
}
res += extension_length;
} else if (extension_type == HandshakeExtension::SignatureAlgorithms) {
dbgln("supported signatures: ");
print_buffer(buffer.slice(res, extension_length));
res += extension_length;
// FIXME: what are we supposed to do here?
} else {
dbgln("Encountered unknown extension {} with length {}", (u16)extension_type, extension_length);
res += extension_length;
}
}
return res;
}
ssize_t TLSv12::handle_finished(ReadonlyBytes buffer, WritePacketStage& write_packets)
{
if (m_context.connection_status < ConnectionStatus::KeyExchange || m_context.connection_status == ConnectionStatus::Established) {
dbgln("unexpected finished message");
return (i8)Error::UnexpectedMessage;
}
write_packets = WritePacketStage::Initial;
if (buffer.size() < 3) {
return (i8)Error::NeedMoreData;
}
size_t index = 3;
u32 size = buffer[0] * 0x10000 + buffer[1] * 0x100 + buffer[2];
if (size < 12) {
dbgln_if(TLS_DEBUG, "finished packet smaller than minimum size: {}", size);
return (i8)Error::BrokenPacket;
}
if (size < buffer.size() - index) {
dbgln_if(TLS_DEBUG, "not enough data after length: {} > {}", size, buffer.size() - index);
return (i8)Error::NeedMoreData;
}
// TODO: Compare Hashes
dbgln_if(TLS_DEBUG, "FIXME: handle_finished :: Check message validity");
m_context.connection_status = ConnectionStatus::Established;
if (m_handshake_timeout_timer) {
// Disable the handshake timeout timer as handshake has been established.
m_handshake_timeout_timer->stop();
m_handshake_timeout_timer->remove_from_parent();
m_handshake_timeout_timer = nullptr;
}
if (on_tls_ready_to_write)
on_tls_ready_to_write(*this);
return index + size;
}
void TLSv12::build_random(PacketBuilder& builder)
{
u8 random_bytes[48];
size_t bytes = 48;
fill_with_random(random_bytes, bytes);
// remove zeros from the random bytes
for (size_t i = 0; i < bytes; ++i) {
if (!random_bytes[i])
random_bytes[i--] = get_random<u8>();
}
if (m_context.is_server) {
dbgln("Server mode not supported");
return;
} else {
*(u16*)random_bytes = AK::convert_between_host_and_network_endian((u16)Version::V12);
}
m_context.premaster_key = ByteBuffer::copy(random_bytes, bytes);
// const auto& certificate_option = verify_chain_and_get_matching_certificate(m_context.extensions.SNI); // if the SNI is empty, we'll make a special case and match *a* leaf certificate.
Optional<size_t> certificate_option = 0;
if (!certificate_option.has_value()) {
dbgln("certificate verification failed :(");
alert(AlertLevel::Critical, AlertDescription::BadCertificate);
return;
}
auto& certificate = m_context.certificates[certificate_option.value()];
#if TLS_DEBUG
dbgln("PreMaster secret");
print_buffer(m_context.premaster_key);
#endif
Crypto::PK::RSA_PKCS1_EME rsa(certificate.public_key.modulus(), 0, certificate.public_key.public_exponent());
u8 out[rsa.output_size()];
auto outbuf = Bytes { out, rsa.output_size() };
rsa.encrypt(m_context.premaster_key, outbuf);
#if TLS_DEBUG
dbgln("Encrypted: ");
print_buffer(outbuf);
#endif
if (!compute_master_secret(bytes)) {
dbgln("oh noes we could not derive a master key :(");
return;
}
builder.append_u24(outbuf.size() + 2);
builder.append((u16)outbuf.size());
builder.append(outbuf);
}
ssize_t TLSv12::handle_payload(ReadonlyBytes vbuffer)
{
if (m_context.connection_status == ConnectionStatus::Established) {
dbgln_if(TLS_DEBUG, "Renegotiation attempt ignored");
// FIXME: We should properly say "NoRenegotiation", but that causes a handshake failure
// so we just roll with it and pretend that we _did_ renegotiate
// This will cause issues when we decide to have long-lasting connections, but
// we do not have those at the moment :^)
return 1;
}
auto buffer = vbuffer;
auto buffer_length = buffer.size();
auto original_length = buffer_length;
while (buffer_length >= 4 && !m_context.critical_error) {
ssize_t payload_res = 0;
if (buffer_length < 1)
return (i8)Error::NeedMoreData;
auto type = buffer[0];
auto write_packets { WritePacketStage::Initial };
size_t payload_size = buffer[1] * 0x10000 + buffer[2] * 0x100 + buffer[3] + 3;
dbgln_if(TLS_DEBUG, "payload size: {} buffer length: {}", payload_size, buffer_length);
if (payload_size + 1 > buffer_length)
return (i8)Error::NeedMoreData;
switch (type) {
case HelloRequest:
if (m_context.handshake_messages[0] >= 1) {
dbgln("unexpected hello request message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[0];
dbgln("hello request (renegotiation?)");
if (m_context.connection_status == ConnectionStatus::Established) {
// renegotiation
payload_res = (i8)Error::NoRenegotiation;
} else {
// :shrug:
payload_res = (i8)Error::UnexpectedMessage;
}
break;
case ClientHello:
// FIXME: We only support client mode right now
if (m_context.is_server) {
VERIFY_NOT_REACHED();
}
payload_res = (i8)Error::UnexpectedMessage;
break;
case ServerHello:
if (m_context.handshake_messages[2] >= 1) {
dbgln("unexpected server hello message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[2];
dbgln_if(TLS_DEBUG, "server hello");
if (m_context.is_server) {
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
}
payload_res = handle_hello(buffer.slice(1, payload_size), write_packets);
break;
case HelloVerifyRequest:
dbgln("unsupported: DTLS");
payload_res = (i8)Error::UnexpectedMessage;
break;
case CertificateMessage:
if (m_context.handshake_messages[4] >= 1) {
dbgln("unexpected certificate message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[4];
dbgln_if(TLS_DEBUG, "certificate");
if (m_context.connection_status == ConnectionStatus::Negotiating) {
if (m_context.is_server) {
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
}
payload_res = handle_certificate(buffer.slice(1, payload_size));
if (m_context.certificates.size()) {
auto it = m_context.certificates.find_if([](const auto& cert) { return cert.is_valid(); });
if (it.is_end()) {
// no valid certificates
dbgln("No valid certificates found");
payload_res = (i8)Error::BadCertificate;
m_context.critical_error = payload_res;
break;
}
// swap the first certificate with the valid one
if (it.index() != 0)
swap(m_context.certificates[0], m_context.certificates[it.index()]);
}
} else {
payload_res = (i8)Error::UnexpectedMessage;
}
break;
case ServerKeyExchange:
if (m_context.handshake_messages[5] >= 1) {
dbgln("unexpected server key exchange message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[5];
dbgln_if(TLS_DEBUG, "server key exchange");
if (m_context.is_server) {
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
} else {
payload_res = handle_server_key_exchange(buffer.slice(1, payload_size));
}
break;
case CertificateRequest:
if (m_context.handshake_messages[6] >= 1) {
dbgln("unexpected certificate request message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[6];
if (m_context.is_server) {
dbgln("invalid request");
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
} else {
// we do not support "certificate request"
dbgln("certificate request");
if (on_tls_certificate_request)
on_tls_certificate_request(*this);
m_context.client_verified = VerificationNeeded;
}
break;
case ServerHelloDone:
if (m_context.handshake_messages[7] >= 1) {
dbgln("unexpected server hello done message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[7];
dbgln_if(TLS_DEBUG, "server hello done");
if (m_context.is_server) {
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
} else {
payload_res = handle_server_hello_done(buffer.slice(1, payload_size));
if (payload_res > 0)
write_packets = WritePacketStage::ClientHandshake;
}
break;
case CertificateVerify:
if (m_context.handshake_messages[8] >= 1) {
dbgln("unexpected certificate verify message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[8];
dbgln_if(TLS_DEBUG, "certificate verify");
if (m_context.connection_status == ConnectionStatus::KeyExchange) {
payload_res = handle_verify(buffer.slice(1, payload_size));
} else {
payload_res = (i8)Error::UnexpectedMessage;
}
break;
case ClientKeyExchange:
if (m_context.handshake_messages[9] >= 1) {
dbgln("unexpected client key exchange message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[9];
dbgln_if(TLS_DEBUG, "client key exchange");
if (m_context.is_server) {
dbgln("unsupported: server mode");
VERIFY_NOT_REACHED();
} else {
payload_res = (i8)Error::UnexpectedMessage;
}
break;
case Finished:
if (m_context.cached_handshake) {
m_context.cached_handshake.clear();
}
if (m_context.handshake_messages[10] >= 1) {
dbgln("unexpected finished message");
payload_res = (i8)Error::UnexpectedMessage;
break;
}
++m_context.handshake_messages[10];
dbgln_if(TLS_DEBUG, "finished");
payload_res = handle_finished(buffer.slice(1, payload_size), write_packets);
if (payload_res > 0) {
memset(m_context.handshake_messages, 0, sizeof(m_context.handshake_messages));
}
break;
default:
dbgln("message type not understood: {}", type);
return (i8)Error::NotUnderstood;
}
if (type != HelloRequest) {
update_hash(buffer.slice(0, payload_size + 1), 0);
}
// if something went wrong, send an alert about it
if (payload_res < 0) {
switch ((Error)payload_res) {
case Error::UnexpectedMessage: {
auto packet = build_alert(true, (u8)AlertDescription::UnexpectedMessage);
write_packet(packet);
break;
}
case Error::CompressionNotSupported: {
auto packet = build_alert(true, (u8)AlertDescription::DecompressionFailure);
write_packet(packet);
break;
}
case Error::BrokenPacket: {
auto packet = build_alert(true, (u8)AlertDescription::DecodeError);
write_packet(packet);
break;
}
case Error::NotVerified: {
auto packet = build_alert(true, (u8)AlertDescription::BadRecordMAC);
write_packet(packet);
break;
}
case Error::BadCertificate: {
auto packet = build_alert(true, (u8)AlertDescription::BadCertificate);
write_packet(packet);
break;
}
case Error::UnsupportedCertificate: {
auto packet = build_alert(true, (u8)AlertDescription::UnsupportedCertificate);
write_packet(packet);
break;
}
case Error::NoCommonCipher: {
auto packet = build_alert(true, (u8)AlertDescription::InsufficientSecurity);
write_packet(packet);
break;
}
case Error::NotUnderstood: {
auto packet = build_alert(true, (u8)AlertDescription::InternalError);
write_packet(packet);
break;
}
case Error::NoRenegotiation: {
auto packet = build_alert(true, (u8)AlertDescription::NoRenegotiation);
write_packet(packet);
break;
}
case Error::DecryptionFailed: {
auto packet = build_alert(true, (u8)AlertDescription::DecryptionFailed);
write_packet(packet);
break;
}
case Error::NeedMoreData:
// Ignore this, as it's not an "error"
dbgln_if(TLS_DEBUG, "More data needed");
break;
default:
dbgln("Unknown TLS::Error with value {}", payload_res);
VERIFY_NOT_REACHED();
break;
}
if (payload_res < 0)
return payload_res;
}
switch (write_packets) {
case WritePacketStage::Initial:
// nothing to write
break;
case WritePacketStage::ClientHandshake:
if (m_context.client_verified == VerificationNeeded) {
dbgln_if(TLS_DEBUG, "> Client Certificate");
auto packet = build_certificate();
write_packet(packet);
m_context.client_verified = Verified;
}
{
dbgln_if(TLS_DEBUG, "> Key exchange");
auto packet = build_client_key_exchange();
write_packet(packet);
}
{
dbgln_if(TLS_DEBUG, "> change cipher spec");
auto packet = build_change_cipher_spec();
write_packet(packet);
}
m_context.cipher_spec_set = 1;
m_context.local_sequence_number = 0;
{
dbgln_if(TLS_DEBUG, "> client finished");
auto packet = build_finished();
write_packet(packet);
}
m_context.cipher_spec_set = 0;
break;
case WritePacketStage::ServerHandshake:
// server handshake
dbgln("UNSUPPORTED: Server mode");
VERIFY_NOT_REACHED();
break;
case WritePacketStage::Finished:
// finished
{
dbgln_if(TLS_DEBUG, "> change cipher spec");
auto packet = build_change_cipher_spec();
write_packet(packet);
}
{
dbgln_if(TLS_DEBUG, "> client finished");
auto packet = build_finished();
write_packet(packet);
}
m_context.connection_status = ConnectionStatus::Established;
break;
}
payload_size++;
buffer_length -= payload_size;
buffer = buffer.slice(payload_size, buffer_length);
}
return original_length;
}
}
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