/*
* 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) 2002-2018 OpenVPN Inc <sales@openvpn.net>
* Copyright (C) 2010-2018 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; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file Control Channel SSL library backend module
*/
#ifndef SSL_BACKEND_H_
#define SSL_BACKEND_H_
#include "buffer.h"
#ifdef ENABLE_CRYPTO_OPENSSL
#include "ssl_openssl.h"
#include "ssl_verify_openssl.h"
#define SSLAPI SSLAPI_OPENSSL
#endif
#ifdef ENABLE_CRYPTO_MBEDTLS
#include "ssl_mbedtls.h"
#include "ssl_verify_mbedtls.h"
#define SSLAPI SSLAPI_MBEDTLS
#endif
/* Ensure that SSLAPI got a sane value if SSL is disabled or unknown */
#ifndef SSLAPI
#define SSLAPI SSLAPI_NONE
#endif
/**
* prototype for struct tls_session from ssl_common.h
*/
struct tls_session;
/**
* Get a tls_cipher_name_pair containing OpenSSL and IANA names for supplied TLS cipher name
*
* @param cipher_name Can be either OpenSSL or IANA cipher name
* @return tls_cipher_name_pair* if found, NULL otherwise
*/
typedef struct { const char *openssl_name; const char *iana_name; } tls_cipher_name_pair;
const tls_cipher_name_pair *tls_get_cipher_name_pair(const char *cipher_name, size_t len);
/*
*
* Functions implemented in ssl.c for use by the backend SSL library
*
*/
/**
* Callback to retrieve the user's password
*
* @param buf Buffer to return the password in
* @param size Size of the buffer
* @param rwflag Unused, needed for OpenSSL compatibility
* @param u Unused, needed for OpenSSL compatibility
*/
int pem_password_callback(char *buf, int size, int rwflag, void *u);
/*
*
* Functions used in ssl.c which must be implemented by the backend SSL library
*
*/
/**
* Perform any static initialisation necessary by the library.
* Called on OpenVPN initialisation
*/
void tls_init_lib(void);
/**
* Free any global SSL library-specific data structures.
*/
void tls_free_lib(void);
/**
* Clear the underlying SSL library's error state.
*/
void tls_clear_error(void);
/**
* Parse a TLS version specifier
*
* @param vstr The TLS version string
* @param extra An optional extra parameter, may be NULL
*
* @return One of the TLS_VER_x constants or TLS_VER_BAD
* if a parse error should be flagged.
*/
#define TLS_VER_BAD -1
#define TLS_VER_UNSPEC 0 /* default */
#define TLS_VER_1_0 1
#define TLS_VER_1_1 2
#define TLS_VER_1_2 3
#define TLS_VER_1_3 4
int tls_version_parse(const char *vstr, const char *extra);
/**
* Return the maximum TLS version (as a TLS_VER_x constant)
* supported by current SSL implementation
*
* @return One of the TLS_VER_x constants (but not TLS_VER_BAD).
*/
int tls_version_max(void);
/**
* Initialise a library-specific TLS context for a server.
*
* @param ctx TLS context to initialise
*/
void tls_ctx_server_new(struct tls_root_ctx *ctx);
/**
* Initialises a library-specific TLS context for a client.
*
* @param ctx TLS context to initialise
*/
void tls_ctx_client_new(struct tls_root_ctx *ctx);
/**
* Frees the library-specific TLSv1 context
*
* @param ctx TLS context to free
*/
void tls_ctx_free(struct tls_root_ctx *ctx);
/**
* Checks whether the given TLS context is initialised
*
* @param ctx TLS context to check
*
* @return true if the context is initialised, false if not.
*/
bool tls_ctx_initialised(struct tls_root_ctx *ctx);
/**
* Set any library specific options.
*
* Examples include disabling session caching, the password callback to use,
* and session verification parameters.
*
* @param ctx TLS context to set options on
* @param ssl_flags SSL flags to set
*
* @return true on success, false otherwise.
*/
bool tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags);
/**
* Restrict the list of ciphers that can be used within the TLS context.
*
* @param ctx TLS context to restrict, must be valid.
* @param ciphers String containing : delimited cipher names, or NULL to use
* sane defaults.
*/
void tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers);
/**
* Set the TLS certificate profile. The profile defines which crypto
* algorithms may be used in the supplied certificate.
*
* @param ctx TLS context to restrict, must be valid.
* @param profile The profile name ('preferred', 'legacy' or 'suiteb').
* Defaults to 'preferred' if NULL.
*/
void tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile);
/**
* Check our certificate notBefore and notAfter fields, and warn if the cert is
* either not yet valid or has expired. Note that this is a non-fatal error,
* since we compare against the system time, which might be incorrect.
*
* @param ctx TLS context to get our certificate from.
*/
void tls_ctx_check_cert_time(const struct tls_root_ctx *ctx);
/**
* Load Diffie Hellman Parameters, and load them into the library-specific
* TLS context.
*
* @param ctx TLS context to use
* @param dh_file The file name to load the parameters from, or
* "[[INLINE]]" in the case of inline files.
* @param dh_file_inline A string containing the parameters
*/
void tls_ctx_load_dh_params(struct tls_root_ctx *ctx, const char *dh_file,
const char *dh_file_inline);
/**
* Load Elliptic Curve Parameters, and load them into the library-specific
* TLS context.
*
* @param ctx TLS context to use
* @param curve_name The name of the elliptic curve to load.
*/
void tls_ctx_load_ecdh_params(struct tls_root_ctx *ctx, const char *curve_name
);
/**
* Load PKCS #12 file for key, cert and (optionally) CA certs, and add to
* library-specific TLS context.
*
* @param ctx TLS context to use
* @param pkcs12_file The file name to load the information from, or
* "[[INLINE]]" in the case of inline files.
* @param pkcs12_file_inline A string containing the information
*
* @return 1 if an error occurred, 0 if parsing was
* successful.
*/
int tls_ctx_load_pkcs12(struct tls_root_ctx *ctx, const char *pkcs12_file,
const char *pkcs12_file_inline, bool load_ca_file
);
/**
* Use Windows cryptoapi for key and cert, and add to library-specific TLS
* context.
*
* @param ctx TLS context to use
* @param crypto_api_cert String representing the certificate to load.
*/
#ifdef ENABLE_CRYPTOAPI
void tls_ctx_load_cryptoapi(struct tls_root_ctx *ctx, const char *cryptoapi_cert);
#endif /* _WIN32 */
/**
* Load certificate file into the given TLS context. If the given certificate
* file contains a certificate chain, load the whole chain.
*
* @param ctx TLS context to use
* @param cert_file The file name to load the certificate from, or
* "[[INLINE]]" in the case of inline files.
* @param cert_file_inline A string containing the certificate
*/
void tls_ctx_load_cert_file(struct tls_root_ctx *ctx, const char *cert_file,
const char *cert_file_inline);
/**
* Load private key file into the given TLS context.
*
* @param ctx TLS context to use
* @param priv_key_file The file name to load the private key from, or
* "[[INLINE]]" in the case of inline files.
* @param priv_key_file_inline A string containing the private key
*
* @return 1 if an error occurred, 0 if parsing was
* successful.
*/
int tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const char *priv_key_file,
const char *priv_key_file_inline);
#ifdef ENABLE_MANAGEMENT
/**
* Tell the management interface to load the given certificate and the external
* private key matching the given certificate.
*
* @param ctx TLS context to use
*
* @return 1 if an error occurred, 0 if successful.
*/
int tls_ctx_use_management_external_key(struct tls_root_ctx *ctx);
#endif /* ENABLE_MANAGEMENT */
/**
* Load certificate authority certificates from the given file or path.
*
* Note that not all SSL libraries support loading from a path.
*
* @param ctx TLS context to use
* @param ca_file The file name to load the CAs from, or
* "[[INLINE]]" in the case of inline files.
* @param ca_file_inline A string containing the CAs
* @param ca_path The path to load the CAs from
*/
void tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
const char *ca_file_inline, const char *ca_path, bool tls_server
);
/**
* Load extra certificate authority certificates from the given file or path.
* These Load extra certificates that are part of our own certificate
* chain but shouldn't be included in the verify chain.
*
*
* @param ctx TLS context to use
* @param extra_certs_file The file name to load the certs from, or
* "[[INLINE]]" in the case of inline files.
* @param extra_certs_file_inline A string containing the certs
*/
void tls_ctx_load_extra_certs(struct tls_root_ctx *ctx, const char *extra_certs_file,
const char *extra_certs_file_inline
);
#ifdef ENABLE_CRYPTO_MBEDTLS
/**
* Add a personalisation string to the mbed TLS RNG, based on the certificate
* loaded into the given context.
*
* @param ctx TLS context to use
*/
void tls_ctx_personalise_random(struct tls_root_ctx *ctx);
#endif
/* **************************************
*
* Key-state specific functions
*
***************************************/
/**
* Initialise the SSL channel part of the given key state. Settings will be
* loaded from a previously initialised TLS context.
*
* @param ks_ssl The SSL channel's state info to initialise
* @param ssl_ctx The TLS context to use when initialising the channel.
* @param is_server Initialise a server?
* @param session The session associated with the given key_state
*/
void key_state_ssl_init(struct key_state_ssl *ks_ssl,
const struct tls_root_ctx *ssl_ctx, bool is_server, struct tls_session *session);
/**
* Free the SSL channel part of the given key state.
*
* @param ks_ssl The SSL channel's state info to free
*/
void key_state_ssl_free(struct key_state_ssl *ks_ssl);
/**
* Reload the Certificate Revocation List for the SSL channel
*
* @param ssl_ctx The TLS context to use when reloading the CRL
* @param crl_file The file name to load the CRL from, or
* "[[INLINE]]" in the case of inline files.
* @param crl_inline A string containing the CRL
*/
void backend_tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx,
const char *crl_file, const char *crl_inline);
/**
* Keying Material Exporters [RFC 5705] allows additional keying material to be
* derived from existing TLS channel. This exported keying material can then be
* used for a variety of purposes.
*
* @param ks_ssl The SSL channel's state info
* @param session The session associated with the given key_state
*/
void
key_state_export_keying_material(struct key_state_ssl *ks_ssl,
struct tls_session *session) __attribute__((nonnull));
/**************************************************************************/
/** @addtogroup control_tls
* @{ */
/** @name Functions for packets to be sent to a remote OpenVPN peer
* @{ */
/**
* Insert a plaintext buffer into the TLS module.
*
* After successfully processing the data, the data in \a buf is zeroized,
* its length set to zero, and a value of \c 1 is returned.
*
* @param ks_ssl - The security parameter state for this %key
* session.
* @param buf - The plaintext message to process.
*
* @return The return value indicates whether the data was successfully
* processed:
* - \c 1: All the data was processed successfully.
* - \c 0: The data was not processed, this function should be called
* again later to retry.
* - \c -1: An error occurred.
*/
int key_state_write_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf);
/**
* Insert plaintext data into the TLS module.
*
* @param ks_ssl - The security parameter state for this %key
* session.
* @param data - A pointer to the data to process.
* @param len - The length in bytes of the data to process.
*
* @return The return value indicates whether the data was successfully
* processed:
* - \c 1: All the data was processed successfully.
* - \c 0: The data was not processed, this function should be called
* again later to retry.
* - \c -1: An error occurred.
*/
int key_state_write_plaintext_const(struct key_state_ssl *ks_ssl,
const uint8_t *data, int len);
/**
* Extract ciphertext data from the TLS module.
*
* If the \a buf buffer has a length other than zero, this function does
* not perform any action and returns 0.
*
* @param ks_ssl - The security parameter state for this %key
* session.
* @param buf - A buffer in which to store the ciphertext.
* @param maxlen - The maximum number of bytes to extract.
*
* @return The return value indicates whether the data was successfully
* processed:
* - \c 1: Data was extracted successfully.
* - \c 0: No data was extracted, this function should be called again
* later to retry.
* - \c -1: An error occurred.
*/
int key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf,
int maxlen);
/** @} name Functions for packets to be sent to a remote OpenVPN peer */
/** @name Functions for packets received from a remote OpenVPN peer
* @{ */
/**
* Insert a ciphertext buffer into the TLS module.
*
* After successfully processing the data, the data in \a buf is zeroized,
* its length set to zero, and a value of \c 1 is returned.
*
* @param ks_ssl - The security parameter state for this %key
* session.
* @param buf - The ciphertext message to process.
*
* @return The return value indicates whether the data was successfully
* processed:
* - \c 1: All the data was processed successfully.
* - \c 0: The data was not processed, this function should be called
* again later to retry.
* - \c -1: An error occurred.
*/
int key_state_write_ciphertext(struct key_state_ssl *ks_ssl,
struct buffer *buf);
/**
* Extract plaintext data from the TLS module.
*
* If the \a buf buffer has a length other than zero, this function does
* not perform any action and returns 0.
*
* @param ks_ssl - The security parameter state for this %key
* session.
* @param buf - A buffer in which to store the plaintext.
* @param maxlen - The maximum number of bytes to extract.
*
* @return The return value indicates whether the data was successfully
* processed:
* - \c 1: Data was extracted successfully.
* - \c 0: No data was extracted, this function should be called again
* later to retry.
* - \c -1: An error occurred.
*/
int key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf,
int maxlen);
/** @} name Functions for packets received from a remote OpenVPN peer */
/** @} addtogroup control_tls */
/* **************************************
*
* Information functions
*
* Print information for the end user.
*
***************************************/
/*
* Print a one line summary of SSL/TLS session handshake.
*/
void print_details(struct key_state_ssl *ks_ssl, const char *prefix);
/*
* Show the TLS ciphers that are available for us to use in the OpenSSL
* library.
*
* @param cipher_list list of allowed TLS cipher, or NULL.
* @param tls_cert_profile TLS certificate crypto profile name.
*/
void
show_available_tls_ciphers(const char *cipher_list,
const char *tls_cert_profile);
/*
* Show the available elliptic curves in the crypto library
*/
void show_available_curves(void);
/*
* The OpenSSL library has a notion of preference in TLS ciphers. Higher
* preference == more secure. Return the highest preference cipher.
*/
void get_highest_preference_tls_cipher(char *buf, int size);
/**
* return a pointer to a static memory area containing the
* name and version number of the SSL library in use
*/
const char *get_ssl_library_version(void);
#endif /* SSL_BACKEND_H_ */