Files

494 lines
13 KiB
C++

// 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) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// Wrap the Apple SSL API as defined in <Security/SecureTransport.h>
// so that it can be used as the SSL layer by the OpenVPN core.
// NOTE: not used in production code.
// Note that the Apple SSL API is missing some functionality (as of
// Mac OS X 10.8) that makes it difficult to use as a drop in replacement
// for OpenSSL or MbedTLS. The biggest issue is that the API doesn't
// allow an SSL context to be built out of PEM-based certificates and
// keys. It requires an "Identity" in the Keychain that was imported
// by the user as a PKCS#12 file.
#ifndef OPENVPN_APPLECRYPTO_SSL_SSLCTX_H
#define OPENVPN_APPLECRYPTO_SSL_SSLCTX_H
#include <string>
#include <Security/SecImportExport.h>
#include <Security/SecItem.h>
#include <Security/SecureTransport.h>
#include <Security/SecKey.h>
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/mode.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/frame/frame.hpp>
#include <openvpn/frame/memq_stream.hpp>
#include <openvpn/pki/epkibase.hpp>
#include <openvpn/apple/cf/cfsec.hpp>
#include <openvpn/apple/cf/error.hpp>
#include <openvpn/ssl/tlsver.hpp>
#include <openvpn/ssl/sslconsts.hpp>
#include <openvpn/ssl/sslapi.hpp>
// An SSL Context is essentially a configuration that can be used
// to generate an arbitrary number of actual SSL connections objects.
// AppleSSLContext is an SSL Context implementation that uses the
// Mac/iOS SSL library as a backend.
namespace openvpn {
// Represents an SSL configuration that can be used
// to instantiate actual SSL sessions.
class AppleSSLContext : public SSLFactoryAPI
{
public:
typedef RCPtr<AppleSSLContext> Ptr;
enum {
MAX_CIPHERTEXT_IN = 64
};
// The data needed to construct an AppleSSLContext.
class Config : public SSLConfigAPI
{
friend class AppleSSLContext;
public:
typedef RCPtr<Config> Ptr;
Config() {}
void load_identity(const std::string& subject_match)
{
identity = load_identity_(subject_match);
if (!identity())
OPENVPN_THROW(ssl_context_error, "AppleSSLContext: identity '" << subject_match << "' undefined");
}
virtual SSLFactoryAPI::Ptr new_factory()
{
return SSLFactoryAPI::Ptr(new AppleSSLContext(this));
}
virtual void set_mode(const Mode& mode_arg)
{
mode = mode_arg;
}
virtual const Mode& get_mode() const
{
return mode;
}
virtual void set_frame(const Frame::Ptr& frame_arg)
{
frame = frame_arg;
}
virtual void load(const OptionList& opt, const unsigned int lflags)
{
// client/server
if (lflags & LF_PARSE_MODE)
mode = opt.exists("client") ? Mode(Mode::CLIENT) : Mode(Mode::SERVER);
// identity
{
const std::string& subject_match = opt.get("identity", 1, 256);
load_identity(subject_match);
}
}
virtual void set_external_pki_callback(ExternalPKIBase* external_pki_arg)
{
not_implemented("set_external_pki_callback");
}
virtual void set_private_key_password(const std::string& pwd)
{
return not_implemented("set_private_key_password");
}
virtual void load_ca(const std::string& ca_txt, bool strict)
{
return not_implemented("load_ca");
}
virtual void load_crl(const std::string& crl_txt)
{
return not_implemented("load_crl");
}
virtual void load_cert(const std::string& cert_txt)
{
return not_implemented("load_cert");
}
virtual void load_cert(const std::string& cert_txt, const std::string& extra_certs_txt)
{
return not_implemented("load_cert");
}
virtual void load_private_key(const std::string& key_txt)
{
return not_implemented("load_private_key");
}
virtual void load_dh(const std::string& dh_txt)
{
return not_implemented("load_dh");
}
virtual void set_debug_level(const int debug_level)
{
return not_implemented("set_debug_level");
}
virtual void set_flags(const unsigned int flags_arg)
{
return not_implemented("set_flags");
}
virtual void set_ns_cert_type(const NSCert::Type ns_cert_type_arg)
{
return not_implemented("set_ns_cert_type");
}
virtual void set_remote_cert_tls(const KUParse::TLSWebType wt)
{
return not_implemented("set_remote_cert_tls");
}
virtual void set_tls_remote(const std::string& tls_remote_arg)
{
return not_implemented("set_tls_remote");
}
virtual void set_tls_version_min(const TLSVersion::Type tvm)
{
return not_implemented("set_tls_version_min");
}
virtual void set_local_cert_enabled(const bool v)
{
return not_implemented("set_local_cert_enabled");
}
virtual void set_enable_renegotiation(const bool v)
{
return not_implemented("set_enable_renegotiation");
}
virtual void set_force_aes_cbc_ciphersuites(const bool v)
{
return not_implemented("set_force_aes_cbc_ciphersuites");
}
virtual void set_rng(const RandomAPI::Ptr& rng_arg)
{
return not_implemented("set_rng");
}
private:
void not_implemented(const char *funcname)
{
OPENVPN_LOG("AppleSSL: " << funcname << " not implemented");
}
Mode mode;
CF::Array identity; // as returned by load_identity
Frame::Ptr frame;
};
// Represents an actual SSL session.
// Normally instantiated by AppleSSLContext::ssl().
class SSL : public SSLAPI
{
friend class AppleSSLContext;
public:
typedef RCPtr<SSL> Ptr;
virtual void start_handshake()
{
SSLHandshake(ssl);
}
virtual ssize_t write_cleartext_unbuffered(const void *data, const size_t size)
{
size_t actual = 0;
const OSStatus status = SSLWrite(ssl, data, size, &actual);
if (status < 0)
{
if (status == errSSLWouldBlock)
return SSLConst::SHOULD_RETRY;
else
throw CFException("AppleSSLContext::SSL::write_cleartext failed", status);
}
else
return actual;
}
virtual ssize_t read_cleartext(void *data, const size_t capacity)
{
if (!overflow)
{
size_t actual = 0;
const OSStatus status = SSLRead(ssl, data, capacity, &actual);
if (status < 0)
{
if (status == errSSLWouldBlock)
return SSLConst::SHOULD_RETRY;
else
throw CFException("AppleSSLContext::SSL::read_cleartext failed", status);
}
else
return actual;
}
else
throw ssl_ciphertext_in_overflow();
}
virtual bool read_cleartext_ready() const
{
// fixme: need to detect data buffered at SSL layer
return !ct_in.empty();
}
virtual void write_ciphertext(const BufferPtr& buf)
{
if (ct_in.size() < MAX_CIPHERTEXT_IN)
ct_in.write_buf(buf);
else
overflow = true;
}
virtual bool read_ciphertext_ready() const
{
return !ct_out.empty();
}
virtual BufferPtr read_ciphertext()
{
return ct_out.read_buf();
}
virtual std::string ssl_handshake_details() const // fixme -- code me
{
return "[AppleSSL not implemented]";
}
virtual const AuthCert::Ptr& auth_cert() const
{
OPENVPN_THROW(ssl_context_error, "AppleSSL::SSL: auth_cert() not implemented");
}
~SSL()
{
ssl_erase();
}
private:
SSL(const AppleSSLContext& ctx)
{
ssl_clear();
try {
OSStatus s;
#ifdef OPENVPN_PLATFORM_IPHONE
// init SSL object, select client or server mode
if (ctx.mode().is_server())
ssl = SSLCreateContext(kCFAllocatorDefault, kSSLServerSide, kSSLStreamType);
else if (ctx.mode().is_client())
ssl = SSLCreateContext(kCFAllocatorDefault, kSSLClientSide, kSSLStreamType);
else
OPENVPN_THROW(ssl_context_error, "AppleSSLContext::SSL: unknown client/server mode");
if (ssl == nullptr)
throw CFException("SSLCreateContext failed");
// use TLS v1
s = SSLSetProtocolVersionMin(ssl, kTLSProtocol1);
if (s)
throw CFException("SSLSetProtocolVersionMin failed", s);
#else
// init SSL object, select client or server mode
if (ctx.mode().is_server())
s = SSLNewContext(true, &ssl);
else if (ctx.mode().is_client())
s = SSLNewContext(false, &ssl);
else
OPENVPN_THROW(ssl_context_error, "AppleSSLContext::SSL: unknown client/server mode");
if (s)
throw CFException("SSLNewContext failed", s);
// use TLS v1
s = SSLSetProtocolVersionEnabled(ssl, kSSLProtocol2, false);
if (s)
throw CFException("SSLSetProtocolVersionEnabled !S2 failed", s);
s = SSLSetProtocolVersionEnabled(ssl, kSSLProtocol3, false);
if (s)
throw CFException("SSLSetProtocolVersionEnabled !S3 failed", s);
s = SSLSetProtocolVersionEnabled(ssl, kTLSProtocol1, true);
if (s)
throw CFException("SSLSetProtocolVersionEnabled T1 failed", s);
#endif
// configure cert, private key, and supporting CAs via identity wrapper
s = SSLSetCertificate(ssl, ctx.identity()());
if (s)
throw CFException("SSLSetCertificate failed", s);
// configure ciphertext buffers
ct_in.set_frame(ctx.frame());
ct_out.set_frame(ctx.frame());
// configure the "connection" object to be self
s = SSLSetConnection(ssl, this);
if (s)
throw CFException("SSLSetConnection", s);
// configure ciphertext read/write callbacks
s = SSLSetIOFuncs(ssl, ct_read_func, ct_write_func);
if (s)
throw CFException("SSLSetIOFuncs failed", s);
}
catch (...)
{
ssl_erase();
throw;
}
}
static OSStatus ct_read_func(SSLConnectionRef cref, void *data, size_t *length)
{
try {
SSL *self = (SSL *)cref;
const size_t actual = self->ct_in.read((unsigned char *)data, *length);
const OSStatus ret = (*length == actual) ? 0 : errSSLWouldBlock;
*length = actual;
return ret;
}
catch (...)
{
return errSSLInternal;
}
}
static OSStatus ct_write_func(SSLConnectionRef cref, const void *data, size_t *length)
{
try {
SSL *self = (SSL *)cref;
self->ct_out.write((const unsigned char *)data, *length);
return 0;
}
catch (...)
{
return errSSLInternal;
}
}
void ssl_clear()
{
ssl = nullptr;
overflow = false;
}
void ssl_erase()
{
if (ssl)
{
#ifdef OPENVPN_PLATFORM_IPHONE
CFRelease(ssl);
#else
SSLDisposeContext(ssl);
#endif
}
ssl_clear();
}
SSLContextRef ssl; // underlying SSL connection object
MemQStream ct_in; // write ciphertext to here
MemQStream ct_out; // read ciphertext from here
bool overflow;
};
/////// start of main class implementation
// create a new SSL instance
virtual SSLAPI::Ptr ssl()
{
return SSL::Ptr(new SSL(*this));
}
// like ssl() above but verify hostname against cert CommonName and/or SubjectAltName
virtual SSLAPI::Ptr ssl(const std::string& hostname)
{
OPENVPN_THROW(ssl_context_error, "AppleSSLContext: ssl session with CommonName and/or SubjectAltName verification not implemented");
}
virtual const Mode& mode() const
{
return config_->mode;
}
private:
AppleSSLContext(Config* config)
: config_(config)
{
if (!config_->identity())
OPENVPN_THROW(ssl_context_error, "AppleSSLContext: identity undefined");
}
const Frame::Ptr& frame() const { return config_->frame; }
const CF::Array& identity() const { return config_->identity; }
// load an identity from keychain, return as an array that can
// be passed to SSLSetCertificate
static CF::Array load_identity_(const std::string& subj_match)
{
const CF::String label = CF::string(subj_match);
const void *keys[] = { kSecClass, kSecMatchSubjectContains, kSecMatchTrustedOnly, kSecReturnRef };
const void *values[] = { kSecClassIdentity, label(), kCFBooleanTrue, kCFBooleanTrue };
const CF::Dict query = CF::dict(keys, values, sizeof(keys)/sizeof(keys[0]));
CF::Generic result;
const OSStatus s = SecItemCopyMatching(query(), result.mod_ref());
if (!s && result.defined())
{
const void *asrc[] = { result() };
return CF::array(asrc, 1);
}
else
return CF::Array(); // not found
}
Config::Ptr config_;
};
typedef AppleSSLContext::Ptr AppleSSLContextPtr;
} // namespace openvpn
#endif // OPENVPN_APPLECRYPTO_SSL_SSLCTX_H