godot/modules/mbedtls/packet_peer_mbed_dtls.cpp
Fabio Alessandrelli 024a4b1f2a mbedTLS: disable weak crypto and TLS versions.
This commit adds a new mbedTLS configuration header to customize the
built-in library (and can be optionally replaced by a platform-specific
one).

Currently, it disables most weak cryptographic functions (with the
notable exceptions of MD5 and SHA-1), along with removing support for
TLS versions 1.0 and 1.1 (making TLSv1.2 the only supported one).
2023-05-10 11:13:19 +02:00

286 lines
8.8 KiB
C++

/**************************************************************************/
/* packet_peer_mbed_dtls.cpp */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#include "packet_peer_mbed_dtls.h"
#include "core/io/file_access.h"
#include "core/io/stream_peer_tls.h"
int PacketPeerMbedDTLS::bio_send(void *ctx, const unsigned char *buf, size_t len) {
if (buf == nullptr || len == 0) {
return 0;
}
PacketPeerMbedDTLS *sp = static_cast<PacketPeerMbedDTLS *>(ctx);
ERR_FAIL_COND_V(sp == nullptr, 0);
Error err = sp->base->put_packet((const uint8_t *)buf, len);
if (err == ERR_BUSY) {
return MBEDTLS_ERR_SSL_WANT_WRITE;
} else if (err != OK) {
ERR_FAIL_V(MBEDTLS_ERR_SSL_INTERNAL_ERROR);
}
return len;
}
int PacketPeerMbedDTLS::bio_recv(void *ctx, unsigned char *buf, size_t len) {
if (buf == nullptr || len == 0) {
return 0;
}
PacketPeerMbedDTLS *sp = static_cast<PacketPeerMbedDTLS *>(ctx);
ERR_FAIL_COND_V(sp == nullptr, 0);
int pc = sp->base->get_available_packet_count();
if (pc == 0) {
return MBEDTLS_ERR_SSL_WANT_READ;
} else if (pc < 0) {
ERR_FAIL_V(MBEDTLS_ERR_SSL_INTERNAL_ERROR);
}
const uint8_t *buffer;
int buffer_size = 0;
Error err = sp->base->get_packet(&buffer, buffer_size);
if (err != OK) {
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
memcpy(buf, buffer, buffer_size);
return buffer_size;
}
void PacketPeerMbedDTLS::_cleanup() {
tls_ctx->clear();
base = Ref<PacketPeer>();
status = STATUS_DISCONNECTED;
}
int PacketPeerMbedDTLS::_set_cookie() {
// Setup DTLS session cookie for this client
uint8_t client_id[18];
IPAddress addr = base->get_packet_address();
uint16_t port = base->get_packet_port();
memcpy(client_id, addr.get_ipv6(), 16);
memcpy(&client_id[16], (uint8_t *)&port, 2);
return mbedtls_ssl_set_client_transport_id(tls_ctx->get_context(), client_id, 18);
}
Error PacketPeerMbedDTLS::_do_handshake() {
int ret = 0;
while ((ret = mbedtls_ssl_handshake(tls_ctx->get_context())) != 0) {
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
if (ret != MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) {
ERR_PRINT("TLS handshake error: " + itos(ret));
TLSContextMbedTLS::print_mbedtls_error(ret);
}
_cleanup();
status = STATUS_ERROR;
return FAILED;
}
// Will retry via poll later
return OK;
}
status = STATUS_CONNECTED;
return OK;
}
Error PacketPeerMbedDTLS::connect_to_peer(Ref<PacketPeerUDP> p_base, const String &p_hostname, Ref<TLSOptions> p_options) {
ERR_FAIL_COND_V(!p_base.is_valid() || !p_base->is_socket_connected(), ERR_INVALID_PARAMETER);
Error err = tls_ctx->init_client(MBEDTLS_SSL_TRANSPORT_DATAGRAM, p_hostname, p_options.is_valid() ? p_options : TLSOptions::client());
ERR_FAIL_COND_V(err != OK, err);
base = p_base;
mbedtls_ssl_set_bio(tls_ctx->get_context(), this, bio_send, bio_recv, nullptr);
mbedtls_ssl_set_timer_cb(tls_ctx->get_context(), &timer, mbedtls_timing_set_delay, mbedtls_timing_get_delay);
status = STATUS_HANDSHAKING;
if (_do_handshake() != OK) {
status = STATUS_ERROR_HOSTNAME_MISMATCH;
return FAILED;
}
return OK;
}
Error PacketPeerMbedDTLS::accept_peer(Ref<PacketPeerUDP> p_base, Ref<TLSOptions> p_options, Ref<CookieContextMbedTLS> p_cookies) {
ERR_FAIL_COND_V(!p_base.is_valid() || !p_base->is_socket_connected(), ERR_INVALID_PARAMETER);
Error err = tls_ctx->init_server(MBEDTLS_SSL_TRANSPORT_DATAGRAM, p_options, p_cookies);
ERR_FAIL_COND_V(err != OK, err);
base = p_base;
base->set_blocking_mode(false);
mbedtls_ssl_session_reset(tls_ctx->get_context());
int ret = _set_cookie();
if (ret != 0) {
_cleanup();
ERR_FAIL_V_MSG(FAILED, "Error setting DTLS client cookie");
}
mbedtls_ssl_set_bio(tls_ctx->get_context(), this, bio_send, bio_recv, nullptr);
mbedtls_ssl_set_timer_cb(tls_ctx->get_context(), &timer, mbedtls_timing_set_delay, mbedtls_timing_get_delay);
status = STATUS_HANDSHAKING;
if (_do_handshake() != OK) {
status = STATUS_ERROR;
return FAILED;
}
return OK;
}
Error PacketPeerMbedDTLS::put_packet(const uint8_t *p_buffer, int p_bytes) {
ERR_FAIL_COND_V(status != STATUS_CONNECTED, ERR_UNCONFIGURED);
if (p_bytes == 0) {
return OK;
}
int ret = mbedtls_ssl_write(tls_ctx->get_context(), p_buffer, p_bytes);
if (ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
// Non blocking io.
} else if (ret <= 0) {
TLSContextMbedTLS::print_mbedtls_error(ret);
_cleanup();
return ERR_CONNECTION_ERROR;
}
return OK;
}
Error PacketPeerMbedDTLS::get_packet(const uint8_t **r_buffer, int &r_bytes) {
ERR_FAIL_COND_V(status != STATUS_CONNECTED, ERR_UNCONFIGURED);
r_bytes = 0;
int ret = mbedtls_ssl_read(tls_ctx->get_context(), packet_buffer, PACKET_BUFFER_SIZE);
if (ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
ret = 0; // non blocking io
} else if (ret <= 0) {
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
// Also send close notify back
disconnect_from_peer();
} else {
_cleanup();
status = STATUS_ERROR;
TLSContextMbedTLS::print_mbedtls_error(ret);
}
return ERR_CONNECTION_ERROR;
}
*r_buffer = packet_buffer;
r_bytes = ret;
return OK;
}
void PacketPeerMbedDTLS::poll() {
if (status == STATUS_HANDSHAKING) {
_do_handshake();
return;
} else if (status != STATUS_CONNECTED) {
return;
}
ERR_FAIL_COND(!base.is_valid());
int ret = mbedtls_ssl_read(tls_ctx->get_context(), nullptr, 0);
if (ret < 0 && ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
// Also send close notify back
disconnect_from_peer();
} else {
_cleanup();
status = STATUS_ERROR;
TLSContextMbedTLS::print_mbedtls_error(ret);
}
}
}
int PacketPeerMbedDTLS::get_available_packet_count() const {
ERR_FAIL_COND_V(status != STATUS_CONNECTED, 0);
return mbedtls_ssl_get_bytes_avail(&(tls_ctx->tls)) > 0 ? 1 : 0;
}
int PacketPeerMbedDTLS::get_max_packet_size() const {
return 488; // 512 (UDP in Godot) - 24 (DTLS header)
}
PacketPeerMbedDTLS::PacketPeerMbedDTLS() {
tls_ctx.instantiate();
}
PacketPeerMbedDTLS::~PacketPeerMbedDTLS() {
disconnect_from_peer();
}
void PacketPeerMbedDTLS::disconnect_from_peer() {
if (status != STATUS_CONNECTED && status != STATUS_HANDSHAKING) {
return;
}
if (status == STATUS_CONNECTED) {
int ret = 0;
// Send SSL close notification, blocking, but ignore other errors.
do {
ret = mbedtls_ssl_close_notify(tls_ctx->get_context());
} while (ret == MBEDTLS_ERR_SSL_WANT_WRITE);
}
_cleanup();
}
PacketPeerMbedDTLS::Status PacketPeerMbedDTLS::get_status() const {
return status;
}
PacketPeerDTLS *PacketPeerMbedDTLS::_create_func() {
return memnew(PacketPeerMbedDTLS);
}
void PacketPeerMbedDTLS::initialize_dtls() {
_create = _create_func;
available = true;
}
void PacketPeerMbedDTLS::finalize_dtls() {
_create = nullptr;
available = false;
}