ssl.h

OpenVPN is a robust and highly flexible tunneling application that uses all of the encryption, authe

  /* true if we are a TLS server, client otherwise */
  bool server;

  /* local and remote options strings
     that must match between client and server */
  const char *local_options;
  const char *remote_options;

  /* from command line */
  int key_method;
  bool replay;
  bool single_session;
  bool disable_occ;
  int transition_window;
  int handshake_window;
  interval_t packet_timeout;
  int renegotiate_bytes;
  int renegotiate_packets;
  interval_t renegotiate_seconds;

  /* cert verification parms */
  const char *verify_command;
  const char *verify_x509name;
  const char *crl_file;

  /* allow openvpn config info to be
     passed over control channel */
  bool pass_config_info;

  /* use 32 bit or 64 bit packet-id? */
  bool packet_id_long_form;

  int replay_window;                   /* --replay-window parm */
  int replay_time;                     /* --replay-window parm */

  /* packet authentication for TLS handshake */
  struct crypto_options tls_auth;
  struct key_ctx_bi tls_auth_key;

  /* frame parameters for TLS control channel */
  struct frame frame;
};

/* index into tls_session.key */
#define KS_PRIMARY    0		/* the primary key */
#define KS_LAME_DUCK  1		/* the key that's going to retire soon */
#define KS_SIZE       2

/*
 * A tls_session lives through multiple key_state life-cycles.  Soft resets
 * will reuse a tls_session object, but hard resets or errors will require
 * that a fresh object be built.  Normally three tls_session objects are maintained
 * by an active openvpn session.  The first is the current, TLS authenticated
 * session, the second is used to process connection requests from a new
 * client that would usurp the current session if successfully authenticated,
 * and the third is used as a repository for a "lame-duck" key in the event
 * that the primary session resets due to error while the lame-duck key still
 * has time left before its expiration.  Lame duck keys are used to maintain
 * the continuity of the data channel connection while a new key is being
 * negotiated.
 */
struct tls_session
{
  /* const options and config info */
  const struct tls_options *opt;

  /* during hard reset used to control burst retransmit */
  bool burst;

  /* authenticate control packets */
  struct crypto_options tls_auth;
  struct packet_id tls_auth_pid;

  int initial_opcode;		/* our initial P_ opcode */
  struct session_id session_id;	/* our random session ID */
  int key_id;			/* increments with each soft reset (for key renegotiation) */

  int limit_next;               /* used for traffic shaping on the control channel */

  int verify_maxlevel;

  char *common_name;

  /* not-yet-authenticated incoming client */
  struct sockaddr_in untrusted_sockaddr;

  struct key_state key[KS_SIZE];
};

/* index into tls_multi.session */
#define TM_ACTIVE    0
#define TM_UNTRUSTED 1
#define TM_LAME_DUCK 2
#define TM_SIZE      3

/*
 * The number of keys we will scan on encrypt or decrypt.  The first
 * is the "active" key.  The second is the lame_duck or retiring key
 * associated with the active key's session ID.  The third is a detached
 * lame duck session that only occurs in situations where a key renegotiate
 * failed on the active key, but a lame duck key was still valid.  By
 * preserving the lame duck session, we can be assured of having a data
 * channel key available even when network conditions are so bad that
 * we can't negotiate a new key within the time allotted.
 */
#define KEY_SCAN_SIZE 3

/*
 * An openvpn session running with TLS enabled has one tls_multi object.
 */
struct tls_multi
{
  /* used to coordinate access between main thread and TLS thread */
  //MUTEX_PTR_DEFINE (mutex);

  /* const options and config info */
  struct tls_options opt;

  /*
   * A list of key_state objects in the order they should be
   * scanned by data channel encrypt and decrypt routines.
   */
  struct key_state* key_scan[KEY_SCAN_SIZE];

  /*
   * used by tls_pre_encrypt to communicate the encrypt key
   * to tls_post_encrypt()
   */
  struct key_state *save_ks;	/* temporary pointer used between pre/post routines */

  /*
   * Number of sessions negotiated thus far.
   */
  int n_sessions;

  /*
   * Number of errors.
   *
   * Includes:
   *   (a) errors due to TLS negotiation failure
   *   (b) errors due to unrecognized or failed-to-authenticate
   *       incoming packets
   */
  int n_errors;

  /*
   * Our session objects.
   */
  struct tls_session session[TM_SIZE];
};

/*
 * 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;
};

void init_ssl_lib (void);
void free_ssl_lib (void);

/* Build master SSL_CTX object that serves for the whole of openvpn instantiation */
SSL_CTX *init_ssl (bool server,
		   const char *ca_file,
		   const char *dh_file,
		   const char *cert_file,
		   const char *priv_key_file, const char *cipher_list);

struct tls_multi *tls_multi_init (struct tls_options *tls_options);

struct tls_auth_standalone *tls_auth_standalone_init (struct tls_options *tls_options,
						      struct gc_arena *gc);

void tls_auth_standalone_finalize (struct tls_auth_standalone *tas,
				   const struct frame *frame);

void tls_multi_init_finalize(struct tls_multi *multi,
			     const struct frame *frame);

void tls_multi_init_set_options(struct tls_multi* multi,
				const char *local,
				const char *remote);

bool tls_multi_process (struct tls_multi *multi,
			struct buffer *to_link,
			struct sockaddr_in *to_link_addr,
			struct link_socket_info *to_link_socket_info,
			interval_t *wakeup);

void tls_multi_free (struct tls_multi *multi, bool clear);

bool tls_pre_decrypt (struct tls_multi *multi,
		      struct sockaddr_in *from,
		      struct buffer *buf,
		      struct crypto_options *opt);

bool tls_pre_decrypt_lite (const struct tls_auth_standalone *tas,
			   const struct sockaddr_in *from,
			   const struct buffer *buf);

void tls_pre_encrypt (struct tls_multi *multi,
		      struct buffer *buf, struct crypto_options *opt);

void tls_post_encrypt (struct tls_multi *multi, struct buffer *buf);

void show_available_tls_ciphers (void);
void get_highest_preference_tls_cipher (char *buf, int size);

int pem_password_callback (char *buf, int size, int rwflag, void *u);

void tls_set_verify_command (const char *cmd);
void tls_set_crl_verify (const char *crl);
void tls_set_verify_x509name (const char *x509name);
int get_max_tls_verify_id (struct tls_multi* multi);
const char *tls_common_name (struct tls_multi* multi, bool null);

void tls_adjust_frame_parameters(struct frame *frame);

bool tls_send_payload (struct tls_multi *multi,
		       const struct buffer *buf);

bool tls_rec_payload (struct tls_multi *multi,
		      struct buffer *buf);

/*
 * inline functions
 */

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;
}

/*
 * 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

#endif /* USE_CRYPTO && USE_SSL */

#endif