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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2017-2018 OpenVPN Technologies, Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// Classes for handling OpenVPN tls-crypt-v2 internals
#ifndef OPENVPN_CRYPTO_TLS_CRYPT_V2_H
#define OPENVPN_CRYPTO_TLS_CRYPT_V2_H
#include <string>
#include <openvpn/common/exception.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/crypto/static_key.hpp>
#include <openvpn/crypto/tls_crypt.hpp>
#include <openvpn/ssl/sslchoose.hpp>
namespace openvpn {
constexpr static const char *tls_crypt_v2_server_key_name = "OpenVPN tls-crypt-v2 server key";
constexpr static const char *tls_crypt_v2_client_key_name = "OpenVPN tls-crypt-v2 client key";
class TLSCryptV2ServerKey
{
public:
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_server_key_parse_error);
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_server_key_encode_error);
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_server_key_bad_size);
TLSCryptV2ServerKey()
: key_size(128),
key(key_size, BufAllocFlags::DESTRUCT_ZERO)
{
}
bool defined() const
{
return key.defined();
}
void parse(const std::string &key_text)
{
if (!SSLLib::PEMAPI::pem_decode(key, key_text.c_str(), key_text.length(), tls_crypt_v2_server_key_name))
throw tls_crypt_v2_server_key_parse_error();
if (key.size() != key_size)
throw tls_crypt_v2_server_key_bad_size();
}
void extract_key(OpenVPNStaticKey &tls_key)
{
std::memcpy(tls_key.raw_alloc(), key.c_data(), key_size);
}
std::string render() const
{
BufferAllocated data(32 + 2 * key.size(), 0);
if (!SSLLib::PEMAPI::pem_encode(data, key.c_data(), key.size(), tls_crypt_v2_server_key_name))
throw tls_crypt_v2_server_key_encode_error();
return std::string((const char *)data.c_data());
}
private:
const size_t key_size;
BufferAllocated key;
};
class TLSCryptV2ClientKey
{
public:
enum
{
WKC_MAX_SIZE = 1024, // bytes
};
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_client_key_parse_error);
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_client_key_encode_error);
OPENVPN_SIMPLE_EXCEPTION(tls_crypt_v2_client_key_bad_size);
TLSCryptV2ClientKey() = delete;
TLSCryptV2ClientKey(TLSCryptContext::Ptr context)
: key_size(OpenVPNStaticKey::KEY_SIZE),
tag_size(context->digest_size())
{
}
bool defined() const
{
return key.defined() && wkc.defined();
}
void parse(const std::string &key_text)
{
BufferAllocated data(key_size + WKC_MAX_SIZE, BufAllocFlags::DESTRUCT_ZERO);
if (!SSLLib::PEMAPI::pem_decode(data, key_text.c_str(), key_text.length(), tls_crypt_v2_client_key_name))
throw tls_crypt_v2_client_key_parse_error();
if (data.size() < (tag_size + key_size))
throw tls_crypt_v2_client_key_bad_size();
key.init(data.data(), key_size, BufAllocFlags::DESTRUCT_ZERO);
wkc.init(data.data() + key_size, data.size() - key_size, BufAllocFlags::DESTRUCT_ZERO);
}
void extract_key(OpenVPNStaticKey &tls_key)
{
std::memcpy(tls_key.raw_alloc(), key.c_data(), key_size);
}
std::string render() const
{
BufferAllocated data(32 + 2 * (key.size() + wkc.size()), 0);
BufferAllocated in(key, BufAllocFlags::GROW);
in.append(wkc);
if (!SSLLib::PEMAPI::pem_encode(data, in.c_data(), in.size(), tls_crypt_v2_client_key_name))
throw tls_crypt_v2_client_key_encode_error();
return std::string((const char *)data.c_data());
}
void extract_wkc(BufferAllocated &wkc_out) const
{
wkc_out = wkc;
}
private:
BufferAllocated key;
BufferAllocated wkc;
const size_t key_size;
const size_t tag_size;
};
// the user can extend the TLSCryptMetadata and the TLSCryptMetadataFactory
// classes to implement its own metadata verification method.
//
// default method is to *ignore* the metadata contained in the WKc sent by the client
class TLSCryptMetadata : public RC<thread_unsafe_refcount>
{
public:
typedef RCPtr<TLSCryptMetadata> Ptr;
// override this method with your own verification mechanism.
//
// If type is -1 it means that metadata is empty.
//
virtual bool verify(int type, Buffer &metadata) const
{
return true;
}
};
// abstract class to be extended when creating other factories
class TLSCryptMetadataFactory : public RC<thread_unsafe_refcount>
{
public:
typedef RCPtr<TLSCryptMetadataFactory> Ptr;
virtual TLSCryptMetadata::Ptr new_obj() = 0;
};
// factory implementation for the basic verification method
class CryptoTLSCryptMetadataFactory : public TLSCryptMetadataFactory
{
public:
TLSCryptMetadata::Ptr new_obj()
{
return new TLSCryptMetadata();
}
};
} // namespace openvpn
#endif /* OPENVPN_CRYPTO_TLS_CRYPT_V2_H */
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