1=pod 2 3=head1 NAME 4 5provider-base 6- The basic OpenSSL library E<lt>-E<gt> provider functions 7 8=head1 SYNOPSIS 9 10 #include <openssl/core_dispatch.h> 11 12 /* 13 * None of these are actual functions, but are displayed like this for 14 * the function signatures for functions that are offered as function 15 * pointers in OSSL_DISPATCH arrays. 16 */ 17 18 /* Functions offered by libcrypto to the providers */ 19 const OSSL_ITEM *core_gettable_params(const OSSL_CORE_HANDLE *handle); 20 int core_get_params(const OSSL_CORE_HANDLE *handle, OSSL_PARAM params[]); 21 22 typedef void (*OSSL_thread_stop_handler_fn)(void *arg); 23 int core_thread_start(const OSSL_CORE_HANDLE *handle, 24 OSSL_thread_stop_handler_fn handfn, 25 void *arg); 26 27 OPENSSL_CORE_CTX *core_get_libctx(const OSSL_CORE_HANDLE *handle); 28 void core_new_error(const OSSL_CORE_HANDLE *handle); 29 void core_set_error_debug(const OSSL_CORE_HANDLE *handle, 30 const char *file, int line, const char *func); 31 void core_vset_error(const OSSL_CORE_HANDLE *handle, 32 uint32_t reason, const char *fmt, va_list args); 33 34 int core_obj_add_sigid(const OSSL_CORE_HANDLE *prov, const char *sign_name, 35 const char *digest_name, const char *pkey_name); 36 int core_obj_create(const OSSL_CORE_HANDLE *handle, const char *oid, 37 const char *sn, const char *ln); 38 39 /* 40 * Some OpenSSL functionality is directly offered to providers via 41 * dispatch 42 */ 43 void *CRYPTO_malloc(size_t num, const char *file, int line); 44 void *CRYPTO_zalloc(size_t num, const char *file, int line); 45 void CRYPTO_free(void *ptr, const char *file, int line); 46 void CRYPTO_clear_free(void *ptr, size_t num, 47 const char *file, int line); 48 void *CRYPTO_realloc(void *addr, size_t num, 49 const char *file, int line); 50 void *CRYPTO_clear_realloc(void *addr, size_t old_num, size_t num, 51 const char *file, int line); 52 void *CRYPTO_secure_malloc(size_t num, const char *file, int line); 53 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line); 54 void CRYPTO_secure_free(void *ptr, const char *file, int line); 55 void CRYPTO_secure_clear_free(void *ptr, size_t num, 56 const char *file, int line); 57 int CRYPTO_secure_allocated(const void *ptr); 58 void OPENSSL_cleanse(void *ptr, size_t len); 59 60 unsigned char *OPENSSL_hexstr2buf(const char *str, long *buflen); 61 62 OSSL_CORE_BIO *BIO_new_file(const char *filename, const char *mode); 63 OSSL_CORE_BIO *BIO_new_membuf(const void *buf, int len); 64 int BIO_read_ex(OSSL_CORE_BIO *bio, void *data, size_t data_len, 65 size_t *bytes_read); 66 int BIO_write_ex(OSSL_CORE_BIO *bio, const void *data, size_t data_len, 67 size_t *written); 68 int BIO_up_ref(OSSL_CORE_BIO *bio); 69 int BIO_free(OSSL_CORE_BIO *bio); 70 int BIO_vprintf(OSSL_CORE_BIO *bio, const char *format, va_list args); 71 int BIO_vsnprintf(char *buf, size_t n, const char *fmt, va_list args); 72 73 void OSSL_SELF_TEST_set_callback(OSSL_LIB_CTX *libctx, OSSL_CALLBACK *cb, 74 void *cbarg); 75 76 size_t get_entropy(const OSSL_CORE_HANDLE *handle, 77 unsigned char **pout, int entropy, 78 size_t min_len, size_t max_len); 79 void cleanup_entropy(const OSSL_CORE_HANDLE *handle, 80 unsigned char *buf, size_t len); 81 size_t get_nonce(const OSSL_CORE_HANDLE *handle, 82 unsigned char **pout, size_t min_len, size_t max_len, 83 const void *salt, size_t salt_len); 84 void cleanup_nonce(const OSSL_CORE_HANDLE *handle, 85 unsigned char *buf, size_t len); 86 87 /* Functions for querying the providers in the application library context */ 88 int provider_register_child_cb(const OSSL_CORE_HANDLE *handle, 89 int (*create_cb)(const OSSL_CORE_HANDLE *provider, 90 void *cbdata), 91 int (*remove_cb)(const OSSL_CORE_HANDLE *provider, 92 void *cbdata), 93 int (*global_props_cb)(const char *props, void *cbdata), 94 void *cbdata); 95 void provider_deregister_child_cb(const OSSL_CORE_HANDLE *handle); 96 const char *provider_name(const OSSL_CORE_HANDLE *prov); 97 void *provider_get0_provider_ctx(const OSSL_CORE_HANDLE *prov); 98 const OSSL_DISPATCH *provider_get0_dispatch(const OSSL_CORE_HANDLE *prov); 99 int provider_up_ref(const OSSL_CORE_HANDLE *prov, int activate); 100 int provider_free(const OSSL_CORE_HANDLE *prov, int deactivate); 101 102 /* Functions offered by the provider to libcrypto */ 103 void provider_teardown(void *provctx); 104 const OSSL_ITEM *provider_gettable_params(void *provctx); 105 int provider_get_params(void *provctx, OSSL_PARAM params[]); 106 const OSSL_ALGORITHM *provider_query_operation(void *provctx, 107 int operation_id, 108 const int *no_store); 109 void provider_unquery_operation(void *provctx, int operation_id, 110 const OSSL_ALGORITHM *algs); 111 const OSSL_ITEM *provider_get_reason_strings(void *provctx); 112 int provider_get_capabilities(void *provctx, const char *capability, 113 OSSL_CALLBACK *cb, void *arg); 114 int provider_self_test(void *provctx); 115 116=head1 DESCRIPTION 117 118All "functions" mentioned here are passed as function pointers between 119F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays, in the call 120of the provider initialization function. See L<provider(7)/Provider> 121for a description of the initialization function. They are known as "upcalls". 122 123All these "functions" have a corresponding function type definition 124named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the 125function pointer from a L<OSSL_DISPATCH(3)> element named 126B<OSSL_FUNC_{name}>. 127For example, the "function" core_gettable_params() has these: 128 129 typedef OSSL_PARAM * 130 (OSSL_FUNC_core_gettable_params_fn)(const OSSL_CORE_HANDLE *handle); 131 static ossl_inline OSSL_NAME_core_gettable_params_fn 132 OSSL_FUNC_core_gettable_params(const OSSL_DISPATCH *opf); 133 134L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as 135macros in L<openssl-core_dispatch.h(7)>, as follows: 136 137For I<in> (the L<OSSL_DISPATCH(3)> array passed from F<libcrypto> to the 138provider): 139 140 core_gettable_params OSSL_FUNC_CORE_GETTABLE_PARAMS 141 core_get_params OSSL_FUNC_CORE_GET_PARAMS 142 core_thread_start OSSL_FUNC_CORE_THREAD_START 143 core_get_libctx OSSL_FUNC_CORE_GET_LIBCTX 144 core_new_error OSSL_FUNC_CORE_NEW_ERROR 145 core_set_error_debug OSSL_FUNC_CORE_SET_ERROR_DEBUG 146 core_vset_error OSSL_FUNC_CORE_VSET_ERROR 147 core_obj_add_sigid OSSL_FUNC_CORE_OBJ_ADD_SIGID 148 core_obj_create OSSL_FUNC_CORE_OBJ_CREATE 149 CRYPTO_malloc OSSL_FUNC_CRYPTO_MALLOC 150 CRYPTO_zalloc OSSL_FUNC_CRYPTO_ZALLOC 151 CRYPTO_free OSSL_FUNC_CRYPTO_FREE 152 CRYPTO_clear_free OSSL_FUNC_CRYPTO_CLEAR_FREE 153 CRYPTO_realloc OSSL_FUNC_CRYPTO_REALLOC 154 CRYPTO_clear_realloc OSSL_FUNC_CRYPTO_CLEAR_REALLOC 155 CRYPTO_secure_malloc OSSL_FUNC_CRYPTO_SECURE_MALLOC 156 CRYPTO_secure_zalloc OSSL_FUNC_CRYPTO_SECURE_ZALLOC 157 CRYPTO_secure_free OSSL_FUNC_CRYPTO_SECURE_FREE 158 CRYPTO_secure_clear_free OSSL_FUNC_CRYPTO_SECURE_CLEAR_FREE 159 CRYPTO_secure_allocated OSSL_FUNC_CRYPTO_SECURE_ALLOCATED 160 BIO_new_file OSSL_FUNC_BIO_NEW_FILE 161 BIO_new_mem_buf OSSL_FUNC_BIO_NEW_MEMBUF 162 BIO_read_ex OSSL_FUNC_BIO_READ_EX 163 BIO_write_ex OSSL_FUNC_BIO_WRITE_EX 164 BIO_up_ref OSSL_FUNC_BIO_UP_REF 165 BIO_free OSSL_FUNC_BIO_FREE 166 BIO_vprintf OSSL_FUNC_BIO_VPRINTF 167 BIO_vsnprintf OSSL_FUNC_BIO_VSNPRINTF 168 BIO_puts OSSL_FUNC_BIO_PUTS 169 BIO_gets OSSL_FUNC_BIO_GETS 170 BIO_ctrl OSSL_FUNC_BIO_CTRL 171 OPENSSL_cleanse OSSL_FUNC_OPENSSL_CLEANSE 172 OSSL_SELF_TEST_set_callback OSSL_FUNC_SELF_TEST_CB 173 ossl_rand_get_entropy OSSL_FUNC_GET_ENTROPY 174 ossl_rand_cleanup_entropy OSSL_FUNC_CLEANUP_ENTROPY 175 ossl_rand_get_nonce OSSL_FUNC_GET_NONCE 176 ossl_rand_cleanup_nonce OSSL_FUNC_CLEANUP_NONCE 177 provider_register_child_cb OSSL_FUNC_PROVIDER_REGISTER_CHILD_CB 178 provider_deregister_child_cb OSSL_FUNC_PROVIDER_DEREGISTER_CHILD_CB 179 provider_name OSSL_FUNC_PROVIDER_NAME 180 provider_get0_provider_ctx OSSL_FUNC_PROVIDER_GET0_PROVIDER_CTX 181 provider_get0_dispatch OSSL_FUNC_PROVIDER_GET0_DISPATCH 182 provider_up_ref OSSL_FUNC_PROVIDER_UP_REF 183 provider_free OSSL_FUNC_PROVIDER_FREE 184 185For I<*out> (the L<OSSL_DISPATCH(3)> array passed from the provider to 186F<libcrypto>): 187 188 provider_teardown OSSL_FUNC_PROVIDER_TEARDOWN 189 provider_gettable_params OSSL_FUNC_PROVIDER_GETTABLE_PARAMS 190 provider_get_params OSSL_FUNC_PROVIDER_GET_PARAMS 191 provider_query_operation OSSL_FUNC_PROVIDER_QUERY_OPERATION 192 provider_unquery_operation OSSL_FUNC_PROVIDER_UNQUERY_OPERATION 193 provider_get_reason_strings OSSL_FUNC_PROVIDER_GET_REASON_STRINGS 194 provider_get_capabilities OSSL_FUNC_PROVIDER_GET_CAPABILITIES 195 provider_self_test OSSL_FUNC_PROVIDER_SELF_TEST 196 197=head2 Core functions 198 199core_gettable_params() returns a constant array of descriptor 200L<OSSL_PARAM(3)>, for parameters that core_get_params() can handle. 201 202core_get_params() retrieves parameters from the core for the given I<handle>. 203See L</Core parameters> below for a description of currently known 204parameters. 205 206The core_thread_start() function informs the core that the provider has stated 207an interest in the current thread. The core will inform the provider when the 208thread eventually stops. It must be passed the I<handle> for this provider, as 209well as a callback I<handfn> which will be called when the thread stops. The 210callback will subsequently be called, with the supplied argument I<arg>, from 211the thread that is stopping and gets passed the provider context as an 212argument. This may be useful to perform thread specific clean up such as 213freeing thread local variables. 214 215core_get_libctx() retrieves the core context in which the library 216object for the current provider is stored, accessible through the I<handle>. 217This function is useful only for built-in providers such as the default 218provider. Never cast this to OSSL_LIB_CTX in a provider that is not 219built-in as the OSSL_LIB_CTX of the library loading the provider might be 220a completely different structure than the OSSL_LIB_CTX of the library the 221provider is linked to. Use L<OSSL_LIB_CTX_new_child(3)> instead to obtain 222a proper library context that is linked to the application library context. 223 224core_new_error(), core_set_error_debug() and core_vset_error() are 225building blocks for reporting an error back to the core, with 226reference to the I<handle>. 227 228=over 4 229 230=item core_new_error() 231 232allocates a new thread specific error record. 233 234This corresponds to the OpenSSL function L<ERR_new(3)>. 235 236=item core_set_error_debug() 237 238sets debugging information in the current thread specific error 239record. 240The debugging information includes the name of the file I<file>, the 241line I<line> and the function name I<func> where the error occurred. 242 243This corresponds to the OpenSSL function L<ERR_set_debug(3)>. 244 245=item core_vset_error() 246 247sets the I<reason> for the error, along with any addition data. 248The I<reason> is a number defined by the provider and used to index 249the reason strings table that's returned by 250provider_get_reason_strings(). 251The additional data is given as a format string I<fmt> and a set of 252arguments I<args>, which are treated in the same manner as with 253BIO_vsnprintf(). 254I<file> and I<line> may also be passed to indicate exactly where the 255error occurred or was reported. 256 257This corresponds to the OpenSSL function L<ERR_vset_error(3)>. 258 259=back 260 261The core_obj_create() function registers a new OID and associated short name 262I<sn> and long name I<ln> for the given I<handle>. It is similar to the OpenSSL 263function L<OBJ_create(3)> except that it returns 1 on success or 0 on failure. 264It will treat as success the case where the OID already exists (even if the 265short name I<sn> or long name I<ln> provided as arguments differ from those 266associated with the existing OID, in which case the new names are not 267associated). 268This function is not thread safe. 269 270The core_obj_add_sigid() function registers a new composite signature algorithm 271(I<sign_name>) consisting of an underlying signature algorithm (I<pkey_name>) 272and digest algorithm (I<digest_name>) for the given I<handle>. It assumes that 273the OIDs for the composite signature algorithm as well as for the underlying 274signature and digest algorithms are either already known to OpenSSL or have been 275registered via a call to core_obj_create(). It corresponds to the OpenSSL 276function L<OBJ_add_sigid(3)>, except that the objects are identified by name 277rather than a numeric NID. Any name (OID, short name or long name) can be used 278to identify the object. It will treat as success the case where the composite 279signature algorithm already exists (even if registered against a different 280underlying signature or digest algorithm). For I<digest_name>, NULL or an 281empty string is permissible for signature algorithms that do not need a digest 282to operate correctly. The function returns 1 on success or 0 on failure. 283This function is not thread safe. 284 285CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_free(), CRYPTO_clear_free(), 286CRYPTO_realloc(), CRYPTO_clear_realloc(), CRYPTO_secure_malloc(), 287CRYPTO_secure_zalloc(), CRYPTO_secure_free(), 288CRYPTO_secure_clear_free(), CRYPTO_secure_allocated(), 289BIO_new_file(), BIO_new_mem_buf(), BIO_read_ex(), BIO_write_ex(), BIO_up_ref(), 290BIO_free(), BIO_vprintf(), BIO_vsnprintf(), BIO_gets(), BIO_puts(), 291BIO_ctrl(), OPENSSL_cleanse() and 292OPENSSL_hexstr2buf() correspond exactly to the public functions with 293the same name. As a matter of fact, the pointers in the L<OSSL_DISPATCH(3)> 294array are typically direct pointers to those public functions. Note that the BIO 295functions take an B<OSSL_CORE_BIO> type rather than the standard B<BIO> 296type. This is to ensure that a provider does not mix BIOs from the core 297with BIOs used on the provider side (the two are not compatible). 298OSSL_SELF_TEST_set_callback() is used to set an optional callback that can be 299passed into a provider. This may be ignored by a provider. 300 301get_entropy() retrieves seeding material from the operating system. 302The seeding material will have at least I<entropy> bytes of randomness and the 303output will have at least I<min_len> and at most I<max_len> bytes. 304The buffer address is stored in I<*pout> and the buffer length is 305returned to the caller. On error, zero is returned. 306 307cleanup_entropy() is used to clean up and free the buffer returned by 308get_entropy(). The entropy pointer returned by get_entropy() is passed in 309B<buf> and its length in B<len>. 310 311get_nonce() retrieves a nonce using the passed I<salt> parameter 312of length I<salt_len> and operating system specific information. 313The I<salt> should contain uniquely identifying information and this is 314included, in an unspecified manner, as part of the output. 315The output is stored in a buffer which contains at least I<min_len> and at 316most I<max_len> bytes. The buffer address is stored in I<*pout> and the 317buffer length returned to the caller. On error, zero is returned. 318 319cleanup_nonce() is used to clean up and free the buffer returned by 320get_nonce(). The nonce pointer returned by get_nonce() is passed in 321B<buf> and its length in B<len>. 322 323provider_register_child_cb() registers callbacks for being informed about the 324loading and unloading of providers in the application's library context. 325I<handle> is this provider's handle and I<cbdata> is this provider's data 326that will be passed back to the callbacks. It returns 1 on success or 0 327otherwise. These callbacks may be called while holding locks in libcrypto. In 328order to avoid deadlocks the callback implementation must not be long running 329and must not call other OpenSSL API functions or upcalls. 330 331I<create_cb> is a callback that will be called when a new provider is loaded 332into the application's library context. It is also called for any providers that 333are already loaded at the point that this callback is registered. The callback 334is passed the handle being used for the new provider being loadded and this 335provider's data in I<cbdata>. It should return 1 on success or 0 on failure. 336 337I<remove_cb> is a callback that will be called when a new provider is unloaded 338from the application's library context. It is passed the handle being used for 339the provider being unloaded and this provider's data in I<cbdata>. It should 340return 1 on success or 0 on failure. 341 342I<global_props_cb> is a callback that will be called when the global properties 343from the parent library context are changed. It should return 1 on success 344or 0 on failure. 345 346provider_deregister_child_cb() unregisters callbacks previously registered via 347provider_register_child_cb(). If provider_register_child_cb() has been called 348then provider_deregister_child_cb() should be called at or before the point that 349this provider's teardown function is called. 350 351provider_name() returns a string giving the name of the provider identified by 352I<handle>. 353 354provider_get0_provider_ctx() returns the provider context that is associated 355with the provider identified by I<prov>. 356 357provider_get0_dispatch() gets the dispatch table registered by the provider 358identified by I<prov> when it initialised. 359 360provider_up_ref() increments the reference count on the provider I<prov>. If 361I<activate> is nonzero then the provider is also loaded if it is not already 362loaded. It returns 1 on success or 0 on failure. 363 364provider_free() decrements the reference count on the provider I<prov>. If 365I<deactivate> is nonzero then the provider is also unloaded if it is not 366already loaded. It returns 1 on success or 0 on failure. 367 368=head2 Provider functions 369 370provider_teardown() is called when a provider is shut down and removed 371from the core's provider store. 372It must free the passed I<provctx>. 373 374provider_gettable_params() should return a constant array of 375descriptor L<OSSL_PARAM(3)>, for parameters that provider_get_params() 376can handle. 377 378provider_get_params() should process the L<OSSL_PARAM(3)> array 379I<params>, setting the values of the parameters it understands. 380 381provider_query_operation() should return a constant L<OSSL_ALGORITHM(3)> 382that corresponds to the given I<operation_id>. 383It should indicate if the core may store a reference to this array by 384setting I<*no_store> to 0 (core may store a reference) or 1 (core may 385not store a reference). 386 387provider_unquery_operation() informs the provider that the result of a 388provider_query_operation() is no longer directly required and that the function 389pointers have been copied. The I<operation_id> should match that passed to 390provider_query_operation() and I<algs> should be its return value. 391 392provider_get_reason_strings() should return a constant L<OSSL_ITEM(3)> 393array that provides reason strings for reason codes the provider may 394use when reporting errors using core_put_error(). 395 396The provider_get_capabilities() function should call the callback I<cb> passing 397it a set of L<OSSL_PARAM(3)>s and the caller supplied argument I<arg>. The 398L<OSSL_PARAM(3)>s should provide details about the capability with the name given 399in the I<capability> argument relevant for the provider context I<provctx>. If a 400provider supports multiple capabilities with the given name then it may call the 401callback multiple times (one for each capability). Capabilities can be useful for 402describing the services that a provider can offer. For further details see the 403L</CAPABILITIES> section below. It should return 1 on success or 0 on error. 404 405The provider_self_test() function should perform known answer tests on a subset 406of the algorithms that it uses, and may also verify the integrity of the 407provider module. It should return 1 on success or 0 on error. It will return 1 408if this function is not used. 409 410None of these functions are mandatory, but a provider is fairly 411useless without at least provider_query_operation(), and 412provider_gettable_params() is fairly useless if not accompanied by 413provider_get_params(). 414 415=head2 Provider parameters 416 417provider_get_params() can return the following provider parameters to the core: 418 419=over 4 420 421=item "name" (B<OSSL_PROV_PARAM_NAME>) <UTF8 ptr> 422 423This points to a string that should give a unique name for the provider. 424 425=item "version" (B<OSSL_PROV_PARAM_VERSION>) <UTF8 ptr> 426 427This points to a string that is a version number associated with this provider. 428OpenSSL in-built providers use OPENSSL_VERSION_STR, but this may be different 429for any third party provider. This string is for informational purposes only. 430 431=item "buildinfo" (B<OSSL_PROV_PARAM_BUILDINFO>) <UTF8 ptr> 432 433This points to a string that is a build information associated with this provider. 434OpenSSL in-built providers use OPENSSL_FULL_VERSION_STR, but this may be 435different for any third party provider. 436 437=item "status" (B<OSSL_PROV_PARAM_STATUS>) <unsigned integer> 438 439This returns 0 if the provider has entered an error state, otherwise it returns 4401. 441 442=back 443 444provider_gettable_params() should return the above parameters. 445 446 447=head2 Core parameters 448 449core_get_params() can retrieve the following core parameters for each provider: 450 451=over 4 452 453=item "openssl-version" (B<OSSL_PROV_PARAM_CORE_VERSION>) <UTF8 string ptr> 454 455This points to the OpenSSL libraries' full version string, i.e. the string 456expanded from the macro B<OPENSSL_VERSION_STR>. 457 458=item "provider-name" (B<OSSL_PROV_PARAM_CORE_PROV_NAME>) <UTF8 string ptr> 459 460This points to the OpenSSL libraries' idea of what the calling provider is named. 461 462=item "module-filename" (B<OSSL_PROV_PARAM_CORE_MODULE_FILENAME>) <UTF8 string ptr> 463 464This points to a string containing the full filename of the providers 465module file. 466 467=back 468 469Additionally, provider specific configuration parameters from the 470config file are available, in dotted name form. 471The dotted name form is a concatenation of section names and final 472config command name separated by periods. 473 474For example, let's say we have the following config example: 475 476 config_diagnostics = 1 477 openssl_conf = openssl_init 478 479 [openssl_init] 480 providers = providers_sect 481 482 [providers_sect] 483 foo = foo_sect 484 485 [foo_sect] 486 activate = 1 487 data1 = 2 488 data2 = str 489 more = foo_more 490 491 [foo_more] 492 data3 = foo,bar 493 494The provider will have these additional parameters available: 495 496=over 4 497 498=item "activate" 499 500pointing at the string "1" 501 502=item "data1" 503 504pointing at the string "2" 505 506=item "data2" 507 508pointing at the string "str" 509 510=item "more.data3" 511 512pointing at the string "foo,bar" 513 514=back 515 516For more information on handling parameters, see L<OSSL_PARAM(3)> as 517L<OSSL_PARAM_int(3)>. 518 519=head1 CAPABILITIES 520 521Capabilities describe some of the services that a provider can offer. 522Applications can query the capabilities to discover those services. 523 524=head3 "TLS-GROUP" Capability 525 526The "TLS-GROUP" capability can be queried by libssl to discover the list of 527TLS groups that a provider can support. Each group supported can be used for 528I<key exchange> (KEX) or I<key encapsulation method> (KEM) during a TLS 529handshake. 530TLS clients can advertise the list of TLS groups they support in the 531supported_groups extension, and TLS servers can select a group from the offered 532list that they also support. In this way a provider can add to the list of 533groups that libssl already supports with additional ones. 534 535Each TLS group that a provider supports should be described via the callback 536passed in through the provider_get_capabilities function. Each group should have 537the following details supplied (all are mandatory, except 538B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>): 539 540=over 4 541 542=item "tls-group-name" (B<OSSL_CAPABILITY_TLS_GROUP_NAME>) <UTF8 string> 543 544The name of the group as given in the IANA TLS Supported Groups registry 545L<https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-8>. 546 547=item "tls-group-name-internal" (B<OSSL_CAPABILITY_TLS_GROUP_NAME_INTERNAL>) <UTF8 string> 548 549The name of the group as known by the provider. This could be the same as the 550"tls-group-name", but does not have to be. 551 552=item "tls-group-id" (B<OSSL_CAPABILITY_TLS_GROUP_ID>) <unsigned integer> 553 554The TLS group id value as given in the IANA TLS Supported Groups registry. 555 556=item "tls-group-alg" (B<OSSL_CAPABILITY_TLS_GROUP_ALG>) <UTF8 string> 557 558The name of a Key Management algorithm that the provider offers and that should 559be used with this group. Keys created should be able to support I<key exchange> 560or I<key encapsulation method> (KEM), as implied by the optional 561B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM> flag. 562The algorithm must support key and parameter generation as well as the 563key/parameter generation parameter, B<OSSL_PKEY_PARAM_GROUP_NAME>. The group 564name given via "tls-group-name-internal" above will be passed via 565B<OSSL_PKEY_PARAM_GROUP_NAME> when libssl wishes to generate keys/parameters. 566 567=item "tls-group-sec-bits" (B<OSSL_CAPABILITY_TLS_GROUP_SECURITY_BITS>) <unsigned integer> 568 569The number of bits of security offered by keys in this group. The number of bits 570should be comparable with the ones given in table 2 and 3 of the NIST SP800-57 571document. 572 573=item "tls-group-is-kem" (B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>) <unsigned integer> 574 575Boolean flag to describe if the group should be used in I<key exchange> (KEX) 576mode (0, default) or in I<key encapsulation method> (KEM) mode (1). 577 578This parameter is optional: if not specified, KEX mode is assumed as the default 579mode for the group. 580 581In KEX mode, in a typical Diffie-Hellman fashion, both sides execute I<keygen> 582then I<derive> against the peer public key. To operate in KEX mode, the group 583implementation must support the provider functions as described in 584L<provider-keyexch(7)>. 585 586In KEM mode, the client executes I<keygen> and sends its public key, the server 587executes I<encapsulate> using the client's public key and sends back the 588resulting I<ciphertext>, finally the client executes I<decapsulate> to retrieve 589the same I<shared secret> generated by the server's I<encapsulate>. To operate 590in KEM mode, the group implementation must support the provider functions as 591described in L<provider-kem(7)>. 592 593Both in KEX and KEM mode, the resulting I<shared secret> is then used according 594to the protocol specification. 595 596=item "tls-min-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_TLS>) <integer> 597 598=item "tls-max-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_TLS>) <integer> 599 600=item "tls-min-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_DTLS>) <integer> 601 602=item "tls-max-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_DTLS>) <integer> 603 604These parameters can be used to describe the minimum and maximum TLS and DTLS 605versions supported by the group. The values equate to the on-the-wire encoding 606of the various TLS versions. For example TLSv1.3 is 0x0304 (772 decimal), and 607TLSv1.2 is 0x0303 (771 decimal). A 0 indicates that there is no defined minimum 608or maximum. A -1 indicates that the group should not be used in that protocol. 609 610=back 611 612=head1 EXAMPLES 613 614This is an example of a simple provider made available as a 615dynamically loadable module. 616It implements the fictitious algorithm C<FOO> for the fictitious 617operation C<BAR>. 618 619 #include <malloc.h> 620 #include <openssl/core.h> 621 #include <openssl/core_dispatch.h> 622 623 /* Errors used in this provider */ 624 #define E_MALLOC 1 625 626 static const OSSL_ITEM reasons[] = { 627 { E_MALLOC, "memory allocation failure" }. 628 { 0, NULL } /* Termination */ 629 }; 630 631 /* 632 * To ensure we get the function signature right, forward declare 633 * them using function types provided by openssl/core_dispatch.h 634 */ 635 OSSL_FUNC_bar_newctx_fn foo_newctx; 636 OSSL_FUNC_bar_freectx_fn foo_freectx; 637 OSSL_FUNC_bar_init_fn foo_init; 638 OSSL_FUNC_bar_update_fn foo_update; 639 OSSL_FUNC_bar_final_fn foo_final; 640 641 OSSL_FUNC_provider_query_operation_fn p_query; 642 OSSL_FUNC_provider_get_reason_strings_fn p_reasons; 643 OSSL_FUNC_provider_teardown_fn p_teardown; 644 645 OSSL_provider_init_fn OSSL_provider_init; 646 647 OSSL_FUNC_core_put_error *c_put_error = NULL; 648 649 /* Provider context */ 650 struct prov_ctx_st { 651 OSSL_CORE_HANDLE *handle; 652 } 653 654 /* operation context for the algorithm FOO */ 655 struct foo_ctx_st { 656 struct prov_ctx_st *provctx; 657 int b; 658 }; 659 660 static void *foo_newctx(void *provctx) 661 { 662 struct foo_ctx_st *fooctx = malloc(sizeof(*fooctx)); 663 664 if (fooctx != NULL) 665 fooctx->provctx = provctx; 666 else 667 c_put_error(provctx->handle, E_MALLOC, __FILE__, __LINE__); 668 return fooctx; 669 } 670 671 static void foo_freectx(void *fooctx) 672 { 673 free(fooctx); 674 } 675 676 static int foo_init(void *vfooctx) 677 { 678 struct foo_ctx_st *fooctx = vfooctx; 679 680 fooctx->b = 0x33; 681 } 682 683 static int foo_update(void *vfooctx, unsigned char *in, size_t inl) 684 { 685 struct foo_ctx_st *fooctx = vfooctx; 686 687 /* did you expect something serious? */ 688 if (inl == 0) 689 return 1; 690 for (; inl-- > 0; in++) 691 *in ^= fooctx->b; 692 return 1; 693 } 694 695 static int foo_final(void *vfooctx) 696 { 697 struct foo_ctx_st *fooctx = vfooctx; 698 699 fooctx->b = 0x66; 700 } 701 702 static const OSSL_DISPATCH foo_fns[] = { 703 { OSSL_FUNC_BAR_NEWCTX, (void (*)(void))foo_newctx }, 704 { OSSL_FUNC_BAR_FREECTX, (void (*)(void))foo_freectx }, 705 { OSSL_FUNC_BAR_INIT, (void (*)(void))foo_init }, 706 { OSSL_FUNC_BAR_UPDATE, (void (*)(void))foo_update }, 707 { OSSL_FUNC_BAR_FINAL, (void (*)(void))foo_final }, 708 { 0, NULL } 709 }; 710 711 static const OSSL_ALGORITHM bars[] = { 712 { "FOO", "provider=chumbawamba", foo_fns }, 713 { NULL, NULL, NULL } 714 }; 715 716 static const OSSL_ALGORITHM *p_query(void *provctx, int operation_id, 717 int *no_store) 718 { 719 switch (operation_id) { 720 case OSSL_OP_BAR: 721 return bars; 722 } 723 return NULL; 724 } 725 726 static const OSSL_ITEM *p_reasons(void *provctx) 727 { 728 return reasons; 729 } 730 731 static void p_teardown(void *provctx) 732 { 733 free(provctx); 734 } 735 736 static const OSSL_DISPATCH prov_fns[] = { 737 { OSSL_FUNC_PROVIDER_TEARDOWN, (void (*)(void))p_teardown }, 738 { OSSL_FUNC_PROVIDER_QUERY_OPERATION, (void (*)(void))p_query }, 739 { OSSL_FUNC_PROVIDER_GET_REASON_STRINGS, (void (*)(void))p_reasons }, 740 { 0, NULL } 741 }; 742 743 int OSSL_provider_init(const OSSL_CORE_HANDLE *handle, 744 const OSSL_DISPATCH *in, 745 const OSSL_DISPATCH **out, 746 void **provctx) 747 { 748 struct prov_ctx_st *pctx = NULL; 749 750 for (; in->function_id != 0; in++) 751 switch (in->function_id) { 752 case OSSL_FUNC_CORE_PUT_ERROR: 753 c_put_error = OSSL_FUNC_core_put_error(in); 754 break; 755 } 756 757 *out = prov_fns; 758 759 if ((pctx = malloc(sizeof(*pctx))) == NULL) { 760 /* 761 * ALEA IACTA EST, if the core retrieves the reason table 762 * regardless, that string will be displayed, otherwise not. 763 */ 764 c_put_error(handle, E_MALLOC, __FILE__, __LINE__); 765 return 0; 766 } 767 pctx->handle = handle; 768 return 1; 769 } 770 771This relies on a few things existing in F<openssl/core_dispatch.h>: 772 773 #define OSSL_OP_BAR 4711 774 775 #define OSSL_FUNC_BAR_NEWCTX 1 776 typedef void *(OSSL_FUNC_bar_newctx_fn)(void *provctx); 777 static ossl_inline OSSL_FUNC_bar_newctx(const OSSL_DISPATCH *opf) 778 { return (OSSL_FUNC_bar_newctx_fn *)opf->function; } 779 780 #define OSSL_FUNC_BAR_FREECTX 2 781 typedef void (OSSL_FUNC_bar_freectx_fn)(void *ctx); 782 static ossl_inline OSSL_FUNC_bar_freectx(const OSSL_DISPATCH *opf) 783 { return (OSSL_FUNC_bar_freectx_fn *)opf->function; } 784 785 #define OSSL_FUNC_BAR_INIT 3 786 typedef void *(OSSL_FUNC_bar_init_fn)(void *ctx); 787 static ossl_inline OSSL_FUNC_bar_init(const OSSL_DISPATCH *opf) 788 { return (OSSL_FUNC_bar_init_fn *)opf->function; } 789 790 #define OSSL_FUNC_BAR_UPDATE 4 791 typedef void *(OSSL_FUNC_bar_update_fn)(void *ctx, 792 unsigned char *in, size_t inl); 793 static ossl_inline OSSL_FUNC_bar_update(const OSSL_DISPATCH *opf) 794 { return (OSSL_FUNC_bar_update_fn *)opf->function; } 795 796 #define OSSL_FUNC_BAR_FINAL 5 797 typedef void *(OSSL_FUNC_bar_final_fn)(void *ctx); 798 static ossl_inline OSSL_FUNC_bar_final(const OSSL_DISPATCH *opf) 799 { return (OSSL_FUNC_bar_final_fn *)opf->function; } 800 801=head1 SEE ALSO 802 803L<provider(7)> 804 805=head1 HISTORY 806 807The concept of providers and everything surrounding them was 808introduced in OpenSSL 3.0. 809 810=head1 COPYRIGHT 811 812Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved. 813 814Licensed under the Apache License 2.0 (the "License"). You may not use 815this file except in compliance with the License. You can obtain a copy 816in the file LICENSE in the source distribution or at 817L<https://www.openssl.org/source/license.html>. 818 819=cut 820