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LibTLS: Implement the extended_master_secret TLS extension

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This commit is contained in:
Michiel Visser 2023-11-25 00:27:45 +01:00 • committed by Ali Mohammad Pur
parent 5ab64320b2
commit e785172290
4 changed files with 34 additions and 6 deletions
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10
Userland/Libraries/LibTLS/Handshake.cpp
View file

@ -75,6 +75,7 @@ ByteBuffer TLSv12::build_hello()
auto elliptic_curves_length = 2 * m_context.options.elliptic_curves.size();
auto supported_ec_point_formats_length = m_context.options.supported_ec_point_formats.size();
bool supports_elliptic_curves = elliptic_curves_length && supported_ec_point_formats_length;
bool enable_extended_master_secret = m_context.options.enable_extended_master_secret;
// signature_algorithms: 2b extension ID, 2b extension length, 2b vector length, 2xN signatures and hashes
extension_length += 2 + 2 + 2 + 2 * m_context.options.supported_signature_algorithms.size();
@ -86,6 +87,9 @@ ByteBuffer TLSv12::build_hello()
if (supports_elliptic_curves)
extension_length += 6 + elliptic_curves_length + 5 + supported_ec_point_formats_length;
if (enable_extended_master_secret)
extension_length += 4;
builder.append((u16)extension_length);
if (sni_length) {
@ -130,6 +134,12 @@ ByteBuffer TLSv12::build_hello()
builder.append((u8)format);
}
if (enable_extended_master_secret) {
// extended_master_secret extension
builder.append((u16)ExtensionType::EXTENDED_MASTER_SECRET);
builder.append((u16)0);
}
if (alpn_length) {
// TODO
VERIFY_NOT_REACHED();

25
Userland/Libraries/LibTLS/HandshakeClient.cpp
View file

@ -126,12 +126,25 @@ bool TLSv12::compute_master_secret_from_pre_master_secret(size_t length)
return false;
}
pseudorandom_function(
m_context.master_key,
m_context.premaster_key,
(u8 const*)"master secret", 13,
ReadonlyBytes { m_context.local_random, sizeof(m_context.local_random) },
ReadonlyBytes { m_context.remote_random, sizeof(m_context.remote_random) });
if (m_context.extensions.extended_master_secret) {
Crypto::Hash::Manager handshake_hash_copy = m_context.handshake_hash.copy();
auto digest = handshake_hash_copy.digest();
auto session_hash = ReadonlyBytes { digest.immutable_data(), handshake_hash_copy.digest_size() };
pseudorandom_function(
m_context.master_key,
m_context.premaster_key,
(u8 const*)"extended master secret", 22,
session_hash,
{});
} else {
pseudorandom_function(
m_context.master_key,
m_context.premaster_key,
(u8 const*)"master secret", 13,
ReadonlyBytes { m_context.local_random, sizeof(m_context.local_random) },
ReadonlyBytes { m_context.remote_random, sizeof(m_context.remote_random) });
}
m_context.premaster_key.clear();
if constexpr (TLS_DEBUG) {

3
Userland/Libraries/LibTLS/HandshakeServer.cpp
View file

@ -189,6 +189,9 @@ ssize_t TLSv12::handle_server_hello(ReadonlyBytes buffer, WritePacketStage& writ
// uncompressed points. Therefore, this extension can be safely ignored as it should always inform us
// that the server supports uncompressed points.
res += extension_length;
} else if (extension_type == ExtensionType::EXTENDED_MASTER_SECRET) {
m_context.extensions.extended_master_secret = true;
res += extension_length;
} else {
dbgln("Encountered unknown extension {} with length {}", enum_to_string(extension_type), extension_length);
res += extension_length;

2
Userland/Libraries/LibTLS/TLSv12.h
View file

@ -181,6 +181,7 @@ struct Options {
OPTION_WITH_DEFAULTS(Function<void(AlertDescription)>, alert_handler, [](auto) {})
OPTION_WITH_DEFAULTS(Function<void()>, finish_callback, [] {})
OPTION_WITH_DEFAULTS(Function<Vector<Certificate>()>, certificate_provider, [] { return Vector<Certificate> {}; })
OPTION_WITH_DEFAULTS(bool, enable_extended_master_secret, true)
#undef OPTION_WITH_DEFAULTS
};
@ -232,6 +233,7 @@ struct Context {
struct {
// Server Name Indicator
DeprecatedString SNI; // I hate your existence
bool extended_master_secret { false };
} extensions;
u8 request_client_certificate { 0 };