From: uazo Date: Thu, 24 Mar 2022 10:08:00 +0000 Subject: Disable TLS resumption Disable resumption feature for all HTTPS and QUIC connections; the feature could be used to track users even without cookies. Sessions are not currently saved to disk in Chromium (although there is support for it) but are long enough to constitute a privacy risk (2h for TLS 1.2 and 7 days for TLS 1.3) if user does not frequently close the browser. Since session information is not kept in the HTTP cache it is not cleared when deleting navigation data (although it is possible to clear it by selecting "passwords"). Two new user configurable flags are introduced: * kDisableTLSResumption, active by default * kLogTLSResumption, that would allow to find in logcat reused sessions in lines matching "SSL Log:" See also: * https://arxiv.org/abs/1810.07304 --- chrome/browser/about_flags.cc | 6 +++ chrome/browser/flag_descriptions.cc | 8 ++++ chrome/browser/flag_descriptions.h | 6 +++ net/base/features.cc | 6 +++ net/base/features.h | 6 +++ net/http/http_network_session.cc | 1 + net/quic/quic_stream_factory.cc | 35 ++++++++++++++++- net/socket/ssl_client_socket_impl.cc | 59 ++++++++++++++++++++++++++++ net/socket/ssl_client_socket_impl.h | 2 + 9 files changed, 128 insertions(+), 1 deletion(-) diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc --- a/chrome/browser/about_flags.cc +++ b/chrome/browser/about_flags.cc @@ -4472,6 +4472,12 @@ const FeatureEntry kFeatureEntries[] = { {"enable-tls13-early-data", flag_descriptions::kEnableTLS13EarlyDataName, flag_descriptions::kEnableTLS13EarlyDataDescription, kOsAll, FEATURE_VALUE_TYPE(net::features::kEnableTLS13EarlyData)}, + {"disable-tls-resumption", flag_descriptions::kDisableTLSResumptionName, + flag_descriptions::kDisableTLSResumptionDescription, kOsAll, + FEATURE_VALUE_TYPE(net::features::kDisableTLSResumption)}, + {"log-tls-resumption", flag_descriptions::kLogTLSResumptionName, + flag_descriptions::kLogTLSResumptionDescription, kOsAll, + FEATURE_VALUE_TYPE(net::features::kLogTLSResumption)}, {"post-quantum-cecpq2", flag_descriptions::kPostQuantumCECPQ2Name, flag_descriptions::kPostQuantumCECPQ2Description, kOsAll, FEATURE_VALUE_TYPE(net::features::kPostQuantumCECPQ2)}, diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc --- a/chrome/browser/flag_descriptions.cc +++ b/chrome/browser/flag_descriptions.cc @@ -922,6 +922,14 @@ const char kEnableTLS13EarlyDataDescription[] = "during the handshake when resuming a connection to a compatible TLS 1.3 " "server."; +const char kDisableTLSResumptionName[] = "Disable TLS Session Resumption"; +const char kDisableTLSResumptionDescription[] = + "Disable TLS session resumption."; + +const char kLogTLSResumptionName[] = "Log TLS Session Resumption"; +const char kLogTLSResumptionDescription[] = + "Log TLS session resumption"; + const char kEnhancedNetworkVoicesName[] = "Enhanced network voices"; const char kEnhancedNetworkVoicesDescription[] = "This option enables high-quality, network-based voices in " diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h --- a/chrome/browser/flag_descriptions.h +++ b/chrome/browser/flag_descriptions.h @@ -532,6 +532,12 @@ extern const char kEnablePreinstalledWebAppDuplicationFixerDescription[]; extern const char kEnableTLS13EarlyDataName[]; extern const char kEnableTLS13EarlyDataDescription[]; +extern const char kDisableTLSResumptionName[]; +extern const char kDisableTLSResumptionDescription[]; + +extern const char kLogTLSResumptionName[]; +extern const char kLogTLSResumptionDescription[]; + extern const char kEnhancedNetworkVoicesName[]; extern const char kEnhancedNetworkVoicesDescription[]; diff --git a/net/base/features.cc b/net/base/features.cc --- a/net/base/features.cc +++ b/net/base/features.cc @@ -112,6 +112,12 @@ const base::FeatureParam kUseDnsHttpsSvcbExtraTimePercent{ const base::Feature kEnableTLS13EarlyData{"EnableTLS13EarlyData", base::FEATURE_DISABLED_BY_DEFAULT}; +const base::Feature kDisableTLSResumption{"DisableTLSResumption", + base::FEATURE_ENABLED_BY_DEFAULT}; + +const base::Feature kLogTLSResumption{"LogTLSResumption", + base::FEATURE_DISABLED_BY_DEFAULT}; + const base::Feature kEncryptedClientHello{"EncryptedClientHello", base::FEATURE_DISABLED_BY_DEFAULT}; diff --git a/net/base/features.h b/net/base/features.h --- a/net/base/features.h +++ b/net/base/features.h @@ -175,6 +175,12 @@ NET_EXPORT extern const base::FeatureParam // Enables TLS 1.3 early data. NET_EXPORT extern const base::Feature kEnableTLS13EarlyData; +// Disables TLS resumption. +NET_EXPORT extern const base::Feature kDisableTLSResumption; + +// Log TLS resumption. +NET_EXPORT extern const base::Feature kLogTLSResumption; + // Enables the TLS Encrypted ClientHello feature. // https://datatracker.ietf.org/doc/html/draft-ietf-tls-esni-13 NET_EXPORT extern const base::Feature kEncryptedClientHello; diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc --- a/net/http/http_network_session.cc +++ b/net/http/http_network_session.cc @@ -232,6 +232,7 @@ HttpNetworkSession::HttpNetworkSession(const HttpNetworkSessionParams& params, next_protos_.push_back(kProtoHTTP11); + DCHECK(context.quic_context->params()->max_server_configs_stored_in_properties == 0); http_server_properties_->SetMaxServerConfigsStoredInProperties( context.quic_context->params()->max_server_configs_stored_in_properties); http_server_properties_->SetBrokenAlternativeServicesDelayParams( diff --git a/net/quic/quic_stream_factory.cc b/net/quic/quic_stream_factory.cc --- a/net/quic/quic_stream_factory.cc +++ b/net/quic/quic_stream_factory.cc @@ -73,6 +73,7 @@ #include "net/third_party/quiche/src/quiche/quic/core/quic_utils.h" #include "net/third_party/quiche/src/quiche/quic/platform/api/quic_flags.h" #include "third_party/boringssl/src/include/openssl/aead.h" +#include "third_party/boringssl/src/include/openssl/ssl.h" #include "url/gurl.h" #include "url/scheme_host_port.h" #include "url/url_constants.h" @@ -229,6 +230,38 @@ std::set HostsFromOrigins(std::set origins) { } // namespace +class BromiteSessionCache : public quic::QuicClientSessionCache { + public: + BromiteSessionCache() = default; + ~BromiteSessionCache() override = default; + + void Insert(const quic::QuicServerId& server_id, + bssl::UniquePtr session, + const quic::TransportParameters& params, + const quic::ApplicationState* application_state) override { + if (base::FeatureList::IsEnabled(net::features::kDisableTLSResumption)) + SSL_SESSION_set_timeout(session.get(), 0); + if (base::FeatureList::IsEnabled(net::features::kLogTLSResumption)) { + LOG(INFO) << "SSL Log: new quic session created " + << server_id.host(); + } + quic::QuicClientSessionCache::Insert(server_id, + std::move(session), params, application_state); + } + + std::unique_ptr Lookup( + const quic::QuicServerId& server_id, quic::QuicWallTime now, + const SSL_CTX* ctx) override { + auto value = quic::QuicClientSessionCache::Lookup(server_id, now, ctx); + if (value != nullptr && + base::FeatureList::IsEnabled(net::features::kLogTLSResumption)) { + LOG(INFO) << "SSL Log: QUIC session resumed " + << server_id.host(); + } + return value; + } +}; + // Refcounted class that owns quic::QuicCryptoClientConfig and tracks how many // consumers are using it currently. When the last reference is freed, the // QuicCryptoClientConfigHandle informs the owning QuicStreamFactory, moves it @@ -2209,7 +2242,7 @@ QuicStreamFactory::CreateCryptoConfigHandle( sct_auditing_delegate_, HostsFromOrigins(params_.origins_to_force_quic_on), actual_network_isolation_key), - std::make_unique(), this); + std::make_unique(), this); quic::QuicCryptoClientConfig* crypto_config = crypto_config_owner->config(); crypto_config->set_user_agent_id(params_.user_agent_id); diff --git a/net/socket/ssl_client_socket_impl.cc b/net/socket/ssl_client_socket_impl.cc --- a/net/socket/ssl_client_socket_impl.cc +++ b/net/socket/ssl_client_socket_impl.cc @@ -404,7 +404,33 @@ SSLClientSocketImpl::SSLClientSocketImpl( CHECK(context_); } +void SSLClientSocketImpl::Log_ssl_session_data(const std::string& tag, SSL_SESSION* session) { + if (session == NULL) { + LOG(INFO) << "SSL Log: " + << tag + << " host: " << host_and_port_.ToString() + << " NIK: " << ssl_config_.network_isolation_key.ToDebugString(); + return; + } + + unsigned len; + auto* session_id = SSL_SESSION_get_id(session, &len); + + const uint8_t *ticket; + size_t ticklen; + SSL_SESSION_get0_ticket(session, &ticket, &ticklen); + + LOG(INFO) << "SSL Log: " + << tag + << " host: " << host_and_port_.ToString() + << " NIK: " << ssl_config_.network_isolation_key.ToDebugString() + << " sessionid: " << base::HexEncode(session_id, len) + << (ticklen > 0 ? " ticket:" + base::HexEncode(ticket, ticklen) : ""); +} + SSLClientSocketImpl::~SSLClientSocketImpl() { + if (base::FeatureList::IsEnabled(net::features::kLogTLSResumption)) + Log_ssl_session_data("Disconnect", NULL); Disconnect(); } @@ -803,6 +829,8 @@ int SSLClientSocketImpl::Init() { } if (session) SSL_set_session(ssl_.get(), session.get()); + if (session && base::FeatureList::IsEnabled(net::features::kLogTLSResumption)) + Log_ssl_session_data("Old session resumed", session.get()); } transport_adapter_ = std::make_unique( @@ -1091,6 +1119,35 @@ int SSLClientSocketImpl::DoHandshakeComplete(int result) { : SSLHandshakeDetails::kTLS13Full; } } + if (base::FeatureList::IsEnabled(net::features::kLogTLSResumption)) { + switch(details) + { + case SSLHandshakeDetails::kTLS13Early: + Log_ssl_session_data("SSL Log: session reused: kTLS13Early mode", NULL); + break; + case SSLHandshakeDetails::kTLS13ResumeWithHelloRetryRequest: + Log_ssl_session_data("SSL Log: session reused: kTLS13ResumeWithHelloRetryRequest mode", NULL); + break; + case SSLHandshakeDetails::kTLS13Resume: + Log_ssl_session_data("SSL Log: session reused: kTLS13Resume mode", NULL); + break; + case SSLHandshakeDetails::kTLS12Resume: + Log_ssl_session_data("SSL Log: session reused: kTLS12Resume mode", NULL); + break; + case SSLHandshakeDetails::kTLS12Full: + Log_ssl_session_data("SSL Log: session reused: kTLS12Full mode", NULL); + break; + case SSLHandshakeDetails::kTLS12FalseStart: + Log_ssl_session_data("SSL Log: session reused: kTLS12FalseStart mode", NULL); + break; + case SSLHandshakeDetails::kTLS13Full: + Log_ssl_session_data("SSL Log: session reused: kTLS13Full mode", NULL); + break; + case SSLHandshakeDetails::kTLS13FullWithHelloRetryRequest: + Log_ssl_session_data("SSL Log: session reused: kTLS13FullWithHelloRetryRequest mode", NULL); + break; + } + } UMA_HISTOGRAM_ENUMERATION("Net.SSLHandshakeDetails", details); // Measure TLS connections that implement the renegotiation_info extension. @@ -1764,6 +1821,8 @@ bool SSLClientSocketImpl::IsRenegotiationAllowed() const { } bool SSLClientSocketImpl::IsCachingEnabled() const { + if (base::FeatureList::IsEnabled(net::features::kDisableTLSResumption)) + return false; return context_->ssl_client_session_cache() != nullptr; } diff --git a/net/socket/ssl_client_socket_impl.h b/net/socket/ssl_client_socket_impl.h --- a/net/socket/ssl_client_socket_impl.h +++ b/net/socket/ssl_client_socket_impl.h @@ -130,6 +130,8 @@ class SSLClientSocketImpl : public SSLClientSocket, friend class SSLClientSocket; friend class SSLContext; + void Log_ssl_session_data(const std::string& tag, SSL_SESSION* session); + int Init(); void DoReadCallback(int result); void DoWriteCallback(int result); -- 2.25.1