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/*
* TLS Client
* (C) 2004-2011,2012,2015,2016 Jack Lloyd
* 2016 Matthias Gierlings
* 2017 Harry Reimann, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/tls_client.h>
#include <botan/tls_messages.h>
#include <botan/internal/tls_handshake_state.h>
#include <botan/internal/stl_util.h>
#include <iterator>
#include <sstream>
namespace Botan {
namespace TLS {
namespace {
class Client_Handshake_State final : public Handshake_State
{
public:
Client_Handshake_State(Handshake_IO* io, Callbacks& cb) :
Handshake_State(io, cb),
m_is_reneg(false)
{}
const Public_Key& get_server_public_key() const
{
BOTAN_ASSERT(server_public_key, "Server sent us a certificate");
return *server_public_key.get();
}
bool is_a_resumption() const { return (resumed_session != nullptr); }
bool is_a_renegotiation() const { return m_is_reneg; }
const secure_vector<uint8_t>& resume_master_secret() const
{
BOTAN_STATE_CHECK(is_a_resumption());
return resumed_session->master_secret();
}
const std::vector<X509_Certificate>& resume_peer_certs() const
{
BOTAN_STATE_CHECK(is_a_resumption());
return resumed_session->peer_certs();
}
std::unique_ptr<Public_Key> server_public_key;
// Used during session resumption
std::unique_ptr<Session> resumed_session;
bool m_is_reneg = false;
};
}
/*
* TLS Client Constructor
*/
Client::Client(Callbacks& callbacks,
Session_Manager& session_manager,
Credentials_Manager& creds,
const Policy& policy,
RandomNumberGenerator& rng,
const Server_Information& info,
const Protocol_Version& offer_version,
const std::vector<std::string>& next_protos,
size_t io_buf_sz) :
Channel(callbacks, session_manager, rng, policy,
false, offer_version.is_datagram_protocol(), io_buf_sz),
m_creds(creds),
m_info(info)
{
init(offer_version, next_protos);
}
Client::Client(output_fn data_output_fn,
data_cb proc_cb,
alert_cb recv_alert_cb,
handshake_cb hs_cb,
Session_Manager& session_manager,
Credentials_Manager& creds,
const Policy& policy,
RandomNumberGenerator& rng,
const Server_Information& info,
const Protocol_Version& offer_version,
const std::vector<std::string>& next_protos,
size_t io_buf_sz) :
Channel(data_output_fn, proc_cb, recv_alert_cb, hs_cb, Channel::handshake_msg_cb(),
session_manager, rng, policy, false, offer_version.is_datagram_protocol(), io_buf_sz),
m_creds(creds),
m_info(info)
{
init(offer_version, next_protos);
}
Client::Client(output_fn data_output_fn,
data_cb proc_cb,
alert_cb recv_alert_cb,
handshake_cb hs_cb,
handshake_msg_cb hs_msg_cb,
Session_Manager& session_manager,
Credentials_Manager& creds,
const Policy& policy,
RandomNumberGenerator& rng,
const Server_Information& info,
const Protocol_Version& offer_version,
const std::vector<std::string>& next_protos) :
Channel(data_output_fn, proc_cb, recv_alert_cb, hs_cb, hs_msg_cb,
session_manager, rng, policy, false, offer_version.is_datagram_protocol()),
m_creds(creds),
m_info(info)
{
init(offer_version, next_protos);
}
void Client::init(const Protocol_Version& protocol_version,
const std::vector<std::string>& next_protocols)
{
const std::string srp_identifier = m_creds.srp_identifier("tls-client", m_info.hostname());
Handshake_State& state = create_handshake_state(protocol_version);
send_client_hello(state, false, protocol_version,
srp_identifier, next_protocols);
}
Handshake_State* Client::new_handshake_state(Handshake_IO* io)
{
return new Client_Handshake_State(io, callbacks());
}
std::vector<X509_Certificate>
Client::get_peer_cert_chain(const Handshake_State& state) const
{
const Client_Handshake_State& cstate = dynamic_cast<const Client_Handshake_State&>(state);
if(cstate.is_a_resumption())
return cstate.resume_peer_certs();
if(state.server_certs())
return state.server_certs()->cert_chain();
return std::vector<X509_Certificate>();
}
/*
* Send a new client hello to renegotiate
*/
void Client::initiate_handshake(Handshake_State& state,
bool force_full_renegotiation)
{
send_client_hello(state, force_full_renegotiation,
policy().latest_supported_version(state.version().is_datagram_protocol()));
}
void Client::send_client_hello(Handshake_State& state_base,
bool force_full_renegotiation,
Protocol_Version version,
const std::string& srp_identifier,
const std::vector<std::string>& next_protocols)
{
Client_Handshake_State& state = dynamic_cast<Client_Handshake_State&>(state_base);
if(state.version().is_datagram_protocol())
state.set_expected_next(HELLO_VERIFY_REQUEST); // optional
state.set_expected_next(SERVER_HELLO);
if(!force_full_renegotiation && !m_info.empty())
{
std::unique_ptr<Session> session_info(new Session);;
if(session_manager().load_from_server_info(m_info, *session_info))
{
/*
Ensure that the session protocol cipher and version are acceptable
If not skip the resume and establish a new session
*/
const bool exact_version = session_info->version() == version;
const bool ok_version =
(session_info->version().is_datagram_protocol() == version.is_datagram_protocol()) &&
policy().acceptable_protocol_version(session_info->version());
const bool session_version_ok = policy().only_resume_with_exact_version() ? exact_version : ok_version;
if(policy().acceptable_ciphersuite(session_info->ciphersuite()) && session_version_ok)
{
if(srp_identifier == "" || session_info->srp_identifier() == srp_identifier)
{
state.client_hello(
new Client_Hello(state.handshake_io(),
state.hash(),
policy(),
callbacks(),
rng(),
secure_renegotiation_data_for_client_hello(),
*session_info,
next_protocols));
state.resumed_session = std::move(session_info);
}
}
}
}
if(!state.client_hello()) // not resuming
{
Client_Hello::Settings client_settings(version, m_info.hostname(), srp_identifier);
state.client_hello(new Client_Hello(
state.handshake_io(),
state.hash(),
policy(),
callbacks(),
rng(),
secure_renegotiation_data_for_client_hello(),
client_settings,
next_protocols));
}
secure_renegotiation_check(state.client_hello());
}
namespace {
bool key_usage_matches_ciphersuite(Key_Constraints usage,
const Ciphersuite& suite)
{
if(usage == NO_CONSTRAINTS)
return true; // anything goes ...
if(suite.kex_method() == Kex_Algo::STATIC_RSA)
{
return (usage & KEY_ENCIPHERMENT) | (usage & DATA_ENCIPHERMENT);
}
else
{
return (usage & DIGITAL_SIGNATURE) | (usage & NON_REPUDIATION);
}
}
}
/*
* Process a handshake message
*/
void Client::process_handshake_msg(const Handshake_State* active_state,
Handshake_State& state_base,
Handshake_Type type,
const std::vector<uint8_t>& contents,
bool epoch0_restart)
{
BOTAN_ASSERT_NOMSG(epoch0_restart == false); // only happens on server side
Client_Handshake_State& state = dynamic_cast<Client_Handshake_State&>(state_base);
if(type == HELLO_REQUEST && active_state)
{
Hello_Request hello_request(contents);
if(state.client_hello())
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE, "Cannot renegotiate during a handshake");
}
if(policy().allow_server_initiated_renegotiation())
{
if(secure_renegotiation_supported() || policy().allow_insecure_renegotiation())
{
state.m_is_reneg = true;
this->initiate_handshake(state, true);
}
else
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE, "Client policy prohibits insecure renegotiation");
}
}
else
{
if(policy().abort_connection_on_undesired_renegotiation())
{
throw TLS_Exception(Alert::NO_RENEGOTIATION, "Client policy prohibits renegotiation");
}
else
{
// RFC 5746 section 4.2
send_warning_alert(Alert::NO_RENEGOTIATION);
}
}
return;
}
state.confirm_transition_to(type);
if(type != HANDSHAKE_CCS && type != FINISHED && type != HELLO_VERIFY_REQUEST)
state.hash().update(state.handshake_io().format(contents, type));
if(type == HELLO_VERIFY_REQUEST)
{
state.set_expected_next(SERVER_HELLO);
state.set_expected_next(HELLO_VERIFY_REQUEST); // might get it again
Hello_Verify_Request hello_verify_request(contents);
state.hello_verify_request(hello_verify_request);
}
else if(type == SERVER_HELLO)
{
state.server_hello(new Server_Hello(contents));
if(!state.client_hello()->offered_suite(state.server_hello()->ciphersuite()))
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server replied with ciphersuite we didn't send");
}
if(!Ciphersuite::by_id(state.server_hello()->ciphersuite()).usable_in_version(state.server_hello()->version()))
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server replied using a ciphersuite not allowed in version it offered");
}
if(Ciphersuite::is_scsv(state.server_hello()->ciphersuite()))
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server replied with a signaling ciphersuite");
}
if(state.server_hello()->compression_method() != 0)
{
throw TLS_Exception(Alert::ILLEGAL_PARAMETER,
"Server replied with non-null compression method");
}
if(state.client_hello()->version() > state.server_hello()->version())
{
if(state.server_hello()->random_signals_downgrade())
throw TLS_Exception(Alert::ILLEGAL_PARAMETER, "Downgrade attack detected");
}
auto client_extn = state.client_hello()->extension_types();
auto server_extn = state.server_hello()->extension_types();
std::vector<Handshake_Extension_Type> diff;
std::set_difference(server_extn.begin(), server_extn.end(),
client_extn.begin(), client_extn.end(),
std::back_inserter(diff));
if(!diff.empty())
{
// Server sent us back an extension we did not send!
std::ostringstream msg;
msg << "Server replied with unsupported extensions:";
for(auto&& d : diff)
msg << " " << static_cast<int>(d);
throw TLS_Exception(Alert::UNSUPPORTED_EXTENSION, msg.str());
}
if(uint16_t srtp = state.server_hello()->srtp_profile())
{
if(!value_exists(state.client_hello()->srtp_profiles(), srtp))
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server replied with DTLS-SRTP alg we did not send");
}
callbacks().tls_examine_extensions(state.server_hello()->extensions(), SERVER);
state.set_version(state.server_hello()->version());
m_application_protocol = state.server_hello()->next_protocol();
secure_renegotiation_check(state.server_hello());
const bool server_returned_same_session_id =
!state.server_hello()->session_id().empty() &&
(state.server_hello()->session_id() == state.client_hello()->session_id());
if(server_returned_same_session_id)
{
// successful resumption
/*
* In this case, we offered the version used in the original
* session, and the server must resume with the same version.
*/
if(state.server_hello()->version() != state.client_hello()->version())
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server resumed session but with wrong version");
if(state.server_hello()->supports_extended_master_secret() &&
!state.resumed_session->supports_extended_master_secret())
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server resumed session but added extended master secret");
}
if(!state.server_hello()->supports_extended_master_secret() &&
state.resumed_session->supports_extended_master_secret())
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server resumed session and removed extended master secret");
}
state.compute_session_keys(state.resume_master_secret());
if(state.server_hello()->supports_session_ticket())
{
state.set_expected_next(NEW_SESSION_TICKET);
}
else
{
state.set_expected_next(HANDSHAKE_CCS);
}
}
else
{
// new session
if(active_state)
{
// Here we are testing things that should not change during a renegotation,
// even if the server creates a new session. Howerver they might change
// in a resumption scenario.
if(active_state->version() != state.server_hello()->version())
throw TLS_Exception(Alert::PROTOCOL_VERSION,
"Server changed version after renegotiation");
if(state.server_hello()->supports_extended_master_secret() !=
active_state->server_hello()->supports_extended_master_secret())
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server changed its mind about extended master secret");
}
}
state.resumed_session.reset(); // non-null if we were attempting a resumption
if(state.client_hello()->version().is_datagram_protocol() !=
state.server_hello()->version().is_datagram_protocol())
{
throw TLS_Exception(Alert::PROTOCOL_VERSION,
"Server replied with different protocol type than we offered");
}
if(state.version() > state.client_hello()->version())
{
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Server replied with later version than client offered");
}
if(state.version().major_version() == 3 && state.version().minor_version() == 0)
{
throw TLS_Exception(Alert::PROTOCOL_VERSION,
"Server attempting to negotiate SSLv3 which is not supported");
}
if(!policy().acceptable_protocol_version(state.version()))
{
throw TLS_Exception(Alert::PROTOCOL_VERSION,
"Server version " + state.version().to_string() +
" is unacceptable by policy");
}
if(state.ciphersuite().signature_used() || state.ciphersuite().kex_method() == Kex_Algo::STATIC_RSA)
{
state.set_expected_next(CERTIFICATE);
}
else if(state.ciphersuite().kex_method() == Kex_Algo::PSK)
{
/* PSK is anonymous so no certificate/cert req message is
ever sent. The server may or may not send a server kex,
depending on if it has an identity hint for us.
(EC)DHE_PSK always sends a server key exchange for the
DH exchange portion, and is covered by block below
*/
state.set_expected_next(SERVER_KEX);
state.set_expected_next(SERVER_HELLO_DONE);
}
else if(state.ciphersuite().kex_method() != Kex_Algo::STATIC_RSA)
{
state.set_expected_next(SERVER_KEX);
}
else
{
state.set_expected_next(CERTIFICATE_REQUEST); // optional
state.set_expected_next(SERVER_HELLO_DONE);
}
}
}
else if(type == CERTIFICATE)
{
state.server_certs(new Certificate(contents, policy()));
const std::vector<X509_Certificate>& server_certs =
state.server_certs()->cert_chain();
if(server_certs.empty())
throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
"Client: No certificates sent by server");
/*
If the server supports certificate status messages,
certificate verification happens after we receive the server hello done,
in case an OCSP response was also available
*/
X509_Certificate server_cert = server_certs[0];
if(active_state && active_state->server_certs())
{
X509_Certificate current_cert = active_state->server_certs()->cert_chain().at(0);
if(current_cert != server_cert)
throw TLS_Exception(Alert::BAD_CERTIFICATE, "Server certificate changed during renegotiation");
}
std::unique_ptr<Public_Key> peer_key(server_cert.subject_public_key());
const std::string expected_key_type =
state.ciphersuite().signature_used() ? state.ciphersuite().sig_algo() : "RSA";
if(peer_key->algo_name() != expected_key_type)
throw TLS_Exception(Alert::ILLEGAL_PARAMETER,
"Certificate key type did not match ciphersuite");
if(!key_usage_matches_ciphersuite(server_cert.constraints(), state.ciphersuite()))
throw TLS_Exception(Alert::BAD_CERTIFICATE,
"Certificate usage constraints do not allow this ciphersuite");
state.server_public_key.reset(peer_key.release());
if(state.ciphersuite().kex_method() != Kex_Algo::STATIC_RSA)
{
state.set_expected_next(SERVER_KEX);
}
else
{
state.set_expected_next(CERTIFICATE_REQUEST); // optional
state.set_expected_next(SERVER_HELLO_DONE);
}
if(state.server_hello()->supports_certificate_status_message())
{
state.set_expected_next(CERTIFICATE_STATUS); // optional
}
else
{
try
{
auto trusted_CAs = m_creds.trusted_certificate_authorities("tls-client", m_info.hostname());
callbacks().tls_verify_cert_chain(server_certs,
{},
trusted_CAs,
Usage_Type::TLS_SERVER_AUTH,
m_info.hostname(),
policy());
}
catch(TLS_Exception&)
{
throw;
}
catch(std::exception& e)
{
throw TLS_Exception(Alert::INTERNAL_ERROR, e.what());
}
}
}
else if(type == CERTIFICATE_STATUS)
{
state.server_cert_status(new Certificate_Status(contents));
if(state.ciphersuite().kex_method() != Kex_Algo::STATIC_RSA)
{
state.set_expected_next(SERVER_KEX);
}
else
{
state.set_expected_next(CERTIFICATE_REQUEST); // optional
state.set_expected_next(SERVER_HELLO_DONE);
}
}
else if(type == SERVER_KEX)
{
if(state.ciphersuite().psk_ciphersuite() == false)
state.set_expected_next(CERTIFICATE_REQUEST); // optional
state.set_expected_next(SERVER_HELLO_DONE);
state.server_kex(
new Server_Key_Exchange(contents,
state.ciphersuite().kex_method(),
state.ciphersuite().auth_method(),
state.version())
);
if(state.ciphersuite().signature_used())
{
const Public_Key& server_key = state.get_server_public_key();
if(!state.server_kex()->verify(server_key, state, policy()))
{
throw TLS_Exception(Alert::DECRYPT_ERROR,
"Bad signature on server key exchange");
}
}
}
else if(type == CERTIFICATE_REQUEST)
{
state.set_expected_next(SERVER_HELLO_DONE);
state.cert_req(new Certificate_Req(contents, state.version()));
}
else if(type == SERVER_HELLO_DONE)
{
state.server_hello_done(new Server_Hello_Done(contents));
if(state.server_certs() != nullptr &&
state.server_hello()->supports_certificate_status_message())
{
try
{
auto trusted_CAs = m_creds.trusted_certificate_authorities("tls-client", m_info.hostname());
std::vector<std::shared_ptr<const OCSP::Response>> ocsp;
if(state.server_cert_status() != nullptr)
{
try {
ocsp.push_back(std::make_shared<OCSP::Response>(state.server_cert_status()->response()));
}
catch(Decoding_Error&)
{
// ignore it here because it might be our fault
}
}
callbacks().tls_verify_cert_chain(state.server_certs()->cert_chain(),
ocsp,
trusted_CAs,
Usage_Type::TLS_SERVER_AUTH,
m_info.hostname(),
policy());
}
catch(TLS_Exception&)
{
throw;
}
catch(std::exception& e)
{
throw TLS_Exception(Alert::INTERNAL_ERROR, e.what());
}
}
if(state.received_handshake_msg(CERTIFICATE_REQUEST))
{
const auto& types = state.cert_req()->acceptable_cert_types();
std::vector<X509_Certificate> client_certs =
m_creds.find_cert_chain(types,
state.cert_req()->acceptable_CAs(),
"tls-client",
m_info.hostname());
state.client_certs(new Certificate(state.handshake_io(),
state.hash(),
client_certs));
}
state.client_kex(
new Client_Key_Exchange(state.handshake_io(),
state,
policy(),
m_creds,
state.server_public_key.get(),
m_info.hostname(),
rng())
);
state.compute_session_keys();
if(state.received_handshake_msg(CERTIFICATE_REQUEST) &&
!state.client_certs()->empty())
{
Private_Key* private_key =
m_creds.private_key_for(state.client_certs()->cert_chain()[0],
"tls-client",
m_info.hostname());
state.client_verify(
new Certificate_Verify(state.handshake_io(),
state,
policy(),
rng(),
private_key)
);
}
state.handshake_io().send(Change_Cipher_Spec());
change_cipher_spec_writer(CLIENT);
state.client_finished(new Finished(state.handshake_io(), state, CLIENT));
if(state.server_hello()->supports_session_ticket())
state.set_expected_next(NEW_SESSION_TICKET);
else
state.set_expected_next(HANDSHAKE_CCS);
}
else if(type == NEW_SESSION_TICKET)
{
state.new_session_ticket(new New_Session_Ticket(contents));
state.set_expected_next(HANDSHAKE_CCS);
}
else if(type == HANDSHAKE_CCS)
{
state.set_expected_next(FINISHED);
change_cipher_spec_reader(CLIENT);
}
else if(type == FINISHED)
{
state.server_finished(new Finished(contents));
if(!state.server_finished()->verify(state, SERVER))
throw TLS_Exception(Alert::DECRYPT_ERROR,
"Finished message didn't verify");
state.hash().update(state.handshake_io().format(contents, type));
if(!state.client_finished()) // session resume case
{
state.handshake_io().send(Change_Cipher_Spec());
change_cipher_spec_writer(CLIENT);
state.client_finished(new Finished(state.handshake_io(), state, CLIENT));
}
std::vector<uint8_t> session_id = state.server_hello()->session_id();
const std::vector<uint8_t>& session_ticket = state.session_ticket();
if(session_id.empty() && !session_ticket.empty())
session_id = make_hello_random(rng(), policy());
Session session_info(
session_id,
state.session_keys().master_secret(),
state.server_hello()->version(),
state.server_hello()->ciphersuite(),
CLIENT,
state.server_hello()->supports_extended_master_secret(),
state.server_hello()->supports_encrypt_then_mac(),
get_peer_cert_chain(state),
session_ticket,
m_info,
"",
state.server_hello()->srtp_profile()
);
const bool should_save = save_session(session_info);
if(session_id.size() > 0 && state.is_a_resumption() == false)
{
if(should_save)
session_manager().save(session_info);
else
session_manager().remove_entry(session_info.session_id());
}
activate_session();
}
else
throw Unexpected_Message("Unknown handshake message received");
}
}
}