/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* 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 (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file Control Channel SSL/Data channel negotiation module
*/
#ifndef OPENVPN_SSL_H
#define OPENVPN_SSL_H
#if defined(USE_CRYPTO) && defined(USE_SSL)
#include "basic.h"
#include "common.h"
#include "crypto.h"
#include "packet_id.h"
#include "session_id.h"
#include "reliable.h"
#include "socket.h"
#include "mtu.h"
#include "options.h"
#include "plugin.h"
#include "ssl_common.h"
#include "ssl_verify.h"
#include "ssl_backend.h"
/* Used in the TLS PRF function */
#define KEY_EXPANSION_ID "OpenVPN"
/* packet opcode (high 5 bits) and key-id (low 3 bits) are combined in one byte */
#define P_KEY_ID_MASK 0x07
#define P_OPCODE_SHIFT 3
/* packet opcodes -- the V1 is intended to allow protocol changes in the future */
#define P_CONTROL_HARD_RESET_CLIENT_V1 1 /* initial key from client, forget previous state */
#define P_CONTROL_HARD_RESET_SERVER_V1 2 /* initial key from server, forget previous state */
#define P_CONTROL_SOFT_RESET_V1 3 /* new key, graceful transition from old to new key */
#define P_CONTROL_V1 4 /* control channel packet (usually TLS ciphertext) */
#define P_ACK_V1 5 /* acknowledgement for packets received */
#define P_DATA_V1 6 /* data channel packet */
/* indicates key_method >= 2 */
#define P_CONTROL_HARD_RESET_CLIENT_V2 7 /* initial key from client, forget previous state */
#define P_CONTROL_HARD_RESET_SERVER_V2 8 /* initial key from server, forget previous state */
/* define the range of legal opcodes */
#define P_FIRST_OPCODE 1
#define P_LAST_OPCODE 8
/* Should we aggregate TLS
* acknowledgements, and tack them onto
* control packets? */
#define TLS_AGGREGATE_ACK
/*
* If TLS_AGGREGATE_ACK, set the
* max number of acknowledgments that
* can "hitch a ride" on an outgoing
* non-P_ACK_V1 control packet.
*/
#define CONTROL_SEND_ACK_MAX 4
/*
* Define number of buffers for send and receive in the reliability layer.
*/
#define TLS_RELIABLE_N_SEND_BUFFERS 4 /* also window size for reliablity layer */
#define TLS_RELIABLE_N_REC_BUFFERS 8
/*
* Various timeouts
*/
#define TLS_MULTI_REFRESH 15 /* call tls_multi_process once every n seconds */
#define TLS_MULTI_HORIZON 2 /* call tls_multi_process frequently for n seconds after
every packet sent/received action */
/*
* The SSL/TLS worker thread will wait at most this many seconds for the
* interprocess communication pipe to the main thread to be ready to accept
* writes.
*/
#define TLS_MULTI_THREAD_SEND_TIMEOUT 5
/* Interval that tls_multi_process should call tls_authentication_status */
#define TLS_MULTI_AUTH_STATUS_INTERVAL 10
/*
* Buffer sizes (also see mtu.h).
*/
/* Maximum length of OCC options string passed as part of auth handshake */
#define TLS_OPTIONS_LEN 512
/* Default field in X509 to be username */
#define X509_USERNAME_FIELD_DEFAULT "CN"
/*
* Range of key exchange methods
*/
#define KEY_METHOD_MIN 1
#define KEY_METHOD_MAX 2
/* key method taken from lower 4 bits */
#define KEY_METHOD_MASK 0x0F
/*
* Measure success rate of TLS handshakes, for debugging only
*/
/* #define MEASURE_TLS_HANDSHAKE_STATS */
/*
* Used in --mode server mode to check tls-auth signature on initial
* packets received from new clients.
*/
struct tls_auth_standalone
{
struct key_ctx_bi tls_auth_key;
struct crypto_options tls_auth_options;
struct frame frame;
};
/*
* Prepare the SSL library for use
*/
void init_ssl_lib (void);
/*
* Free any internal state that the SSL library might have
*/
void free_ssl_lib (void);
/**
* Build master SSL context object that serves for the whole of OpenVPN
* instantiation
*/
void init_ssl (const struct options *options, struct tls_root_ctx *ctx);
/** @addtogroup control_processor
* @{ */
/** @name Functions for initialization and cleanup of tls_multi structures
* @{ */
/**
* Allocate and initialize a \c tls_multi structure.
* @ingroup control_processor
*
* This function allocates a new \c tls_multi structure, and performs some
* amount of initialization. Afterwards, the \c tls_multi_init_finalize()
* function must be called to finalize the structure's initialization
* process.
*
* @param tls_options - The configuration options to be used for this VPN
* tunnel.
*
* @return A newly allocated and initialized \c tls_multi structure.
*/
struct tls_multi *tls_multi_init (struct tls_options *tls_options);
/**
* Finalize initialization of a \c tls_multi structure.
* @ingroup control_processor
*
* This function initializes the \c TM_ACTIVE \c tls_session, and in
* server mode also the \c TM_UNTRUSTED \c tls_session, associated with
* this \c tls_multi structure. It also configures the control channel's
* \c frame structure based on the data channel's \c frame given in
* argument \a frame.
*
* @param multi - The \c tls_multi structure of which to finalize
* initialization.
* @param frame - The data channel's \c frame structure.
*/
void tls_multi_init_finalize(struct tls_multi *multi,
const struct frame *frame);
/*
* Initialize a standalone tls-auth verification object.
*/
struct tls_auth_standalone *tls_auth_standalone_init (struct tls_options *tls_options,
struct gc_arena *gc);
/*
* Finalize a standalone tls-auth verification object.
*/
void tls_auth_standalone_finalize (struct tls_auth_standalone *tas,
const struct frame *frame);
/*
* Set local and remote option compatibility strings.
* Used to verify compatibility of local and remote option
* sets.
*/
void tls_multi_init_set_options(struct tls_multi* multi,
const char *local,
const char *remote);
/**
* Cleanup a \c tls_multi structure and free associated memory
* allocations.
* @ingroup control_processor
*
* This function cleans up a \c tls_multi structure. This includes
* cleaning up all associated \c tls_session structures.
*
* @param multi - The \c tls_multi structure to clean up in free.
* @param clear - Whether the memory allocated for the \a multi
* object should be overwritten with 0s.
*/
void tls_multi_free (struct tls_multi *multi, bool clear);
/** @} name Functions for initialization and cleanup of tls_multi structures */
/** @} addtogroup control_processor */
#define TLSMP_INACTIVE 0
#define TLSMP_ACTIVE 1
#define TLSMP_KILL 2
/*
* Called by the top-level event loop.
*
* Basically decides if we should call tls_process for
* the active or untrusted sessions.
*/
int tls_multi_process (struct tls_multi *multi,
struct buffer *to_link,
struct link_socket_actual **to_link_addr,
struct link_socket_info *to_link_socket_info,
interval_t *wakeup);
/**************************************************************************/
/**
* Determine whether an incoming packet is a data channel or control
* channel packet, and process accordingly.
* @ingroup external_multiplexer
*
* When OpenVPN is in TLS mode, this is the first function to process an
* incoming packet. It inspects the packet's one-byte header which
* contains the packet's opcode and key ID. Depending on the opcode, the
* packet is processed as a data channel or as a control channel packet.
*
* @par Data channel packets
*
* If the opcode indicates the packet is a data channel packet, then the
* packet's key ID is used to find the local TLS state it is associated
* with. This state is checked whether it is active, authenticated, and
* its remote peer is the source of this packet. If these checks passed,
* the state's security parameters are loaded into the \a opt crypto
* options so that \p openvpn_decrypt() can later use them to authenticate
* and decrypt the packet.
*
* This function then returns false. The \a buf buffer has not been
* modified, except for removing the header.
*
* @par Control channel packets
*
* If the opcode indicates the packet is a control channel packet, then
* this function will process it based on its plaintext header. depending
* on the packet's opcode and session ID this function determines if it is
* destined for an active TLS session, or whether a new TLS session should
* be started. This function also initiates data channel session key
* renegotiation if the received opcode requests that.
*
* If the incoming packet is destined for an active TLS session, then the
* packet is inserted into the Reliability Layer and will be handled
* later.
*
* @param multi - The TLS multi structure associated with the VPN tunnel
* of this packet.
* @param from - The source address of the packet.
* @param buf - A buffer structure containing the incoming packet.
* @param opt - A crypto options structure that will be loaded with the
* appropriate security parameters to handle the packet if it is a
* data channel packet.
*
* @return
* @li True if the packet is a control channel packet that has been
* processed successfully.
* @li False if the packet is a data channel packet, or if an error
* occurred during processing of a control channel packet.
*/
bool tls_pre_decrypt (struct tls_multi *multi,
const struct link_socket_actual *from,
struct buffer *buf,
struct crypto_options *opt);
/**************************************************************************/
/** @name Functions for managing security parameter state for data channel packets
* @{ */
/**
* Inspect an incoming packet for which no VPN tunnel is active, and
* determine whether a new VPN tunnel should be created.
* @ingroup data_crypto
*
* This function receives the initial incoming packet from a client that
* wishes to establish a new VPN tunnel, and determines the packet is a
* valid initial packet. It is only used when OpenVPN is running in
* server mode.
*
* The tests performed by this function are whether the packet's opcode is
* correct for establishing a new VPN tunnel, whether its key ID is 0, and
* whether its size is not too large. This function also performs the
* initial HMAC firewall test, if configured to do so.
*
* The incoming packet and the local VPN tunnel state are not modified by
* this function. Its sole purpose is to inspect the packet and determine
* whether a new VPN tunnel should be created. If so, that new VPN tunnel
* instance will handle processing of the packet.
*
* @param tas - The standalone TLS authentication setting structure for
* this process.
* @param from - The source address of the packet.
* @param buf - A buffer structure containing the incoming packet.
*
* @return
* @li True if the packet is valid and a new VPN tunnel should be created
* for this client.
* @li False if the packet is not valid, did not pass the HMAC firewall
* test, or some other error occurred.
*/
bool tls_pre_decrypt_lite (const struct tls_auth_standalone *tas,
const struct link_socket_actual *from,
const struct buffer *buf);
/**
* Choose the appropriate security parameters with which to process an
* outgoing packet.
* @ingroup data_crypto
*
* If no appropriate security parameters can be found, or if some other
* error occurs, then the buffer is set to empty.
*
* @param multi - The TLS state for this packet's destination VPN tunnel.
* @param buf - The buffer containing the outgoing packet.
* @param opt - The crypto options structure into which the appropriate
* security parameters should be loaded.
*/
void tls_pre_encrypt (struct tls_multi *multi,
struct buffer *buf, struct crypto_options *opt);
/**
* Prepend the one-byte OpenVPN header to the packet, and perform some
* accounting for the key state used.
* @ingroup data_crypto
*
* @param multi - The TLS state for this packet's destination VPN tunnel.
* @param buf - The buffer containing the outgoing packet.
*/
void tls_post_encrypt (struct tls_multi *multi, struct buffer *buf);
/** @} name Functions for managing security parameter state for data channel packets */
/*
* Setup private key file password. If auth_file is given, use the
* credentials stored in the file.
*/
void pem_password_setup (const char *auth_file);
/*
* Setup authentication username and password. If auth_file is given, use the
* credentials stored in the file.
*/
void auth_user_pass_setup (const char *auth_file, const struct static_challenge_info *sc_info);
/*
* Ensure that no caching is performed on authentication information
*/
void ssl_set_auth_nocache (void);
/*
* Purge any stored authentication information, both for key files and tunnel
* authentication. If PCKS #11 is enabled, purge authentication for that too.
*/
void ssl_purge_auth (const bool auth_user_pass_only);
void ssl_set_auth_token (const char *token);
#ifdef ENABLE_CLIENT_CR
/*
* ssl_get_auth_challenge will parse the server-pushed auth-failed
* reason string and return a dynamically allocated
* auth_challenge_info struct.
*/
void ssl_purge_auth_challenge (void);
void ssl_put_auth_challenge (const char *cr_str);
#endif
/*
* Reserve any extra space required on frames.
*/
void tls_adjust_frame_parameters(struct frame *frame);
/*
* Send a payload over the TLS control channel
*/
bool tls_send_payload (struct tls_multi *multi,
const uint8_t *data,
int size);
/*
* Receive a payload through the TLS control channel
*/
bool tls_rec_payload (struct tls_multi *multi,
struct buffer *buf);
#ifdef MANAGEMENT_DEF_AUTH
static inline char *
tls_get_peer_info(const struct tls_multi *multi)
{
return multi->peer_info;
}
#endif
/*
* inline functions
*/
static inline bool
tls_initial_packet_received (const struct tls_multi *multi)
{
return multi->n_sessions > 0;
}
static inline bool
tls_test_auth_deferred_interval (const struct tls_multi *multi)
{
if (multi)
{
const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
return now < ks->auth_deferred_expire;
}
return false;
}
static inline int
tls_test_payload_len (const struct tls_multi *multi)
{
if (multi)
{
const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
if (ks->state >= S_ACTIVE)
return BLEN (&ks->plaintext_read_buf);
}
return 0;
}
static inline void
tls_set_single_session (struct tls_multi *multi)
{
if (multi)
multi->opt.single_session = true;
}
/*
* protocol_dump() flags
*/
#define PD_TLS_AUTH_HMAC_SIZE_MASK 0xFF
#define PD_SHOW_DATA (1<<8)
#define PD_TLS (1<<9)
#define PD_VERBOSE (1<<10)
const char *protocol_dump (struct buffer *buffer,
unsigned int flags,
struct gc_arena *gc);
/*
* debugging code
*/
#ifdef MEASURE_TLS_HANDSHAKE_STATS
void show_tls_performance_stats(void);
#endif
/*#define EXTRACT_X509_FIELD_TEST*/
void extract_x509_field_test (void);
#endif /* USE_CRYPTO && USE_SSL */
#endif