/* * 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. * Copyright (C) 2010 Fox Crypto B.V. * * 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(ENABLE_CRYPTO) #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_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 */ #define P_DATA_V2 9 /* data channel packet with peer-id */ /* 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 9 /* 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, bool floated); /**************************************************************************/ /** @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); /** * Updates remote address in TLS sessions. * * @param multi - Tunnel to update * @param addr - new address */ void tls_update_remote_addr (struct tls_multi *multi, const struct link_socket_actual *addr); #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 /* ENABLE_CRYPTO */ #endif