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_memdup(const void *str, size_t siz, 46 const char *file, int line); 47 char *CRYPTO_strdup(const char *str, const char *file, int line); 48 char *CRYPTO_strndup(const char *str, size_t s, 49 const char *file, int line); 50 void CRYPTO_free(void *ptr, const char *file, int line); 51 void CRYPTO_clear_free(void *ptr, size_t num, 52 const char *file, int line); 53 void *CRYPTO_realloc(void *addr, size_t num, 54 const char *file, int line); 55 void *CRYPTO_clear_realloc(void *addr, size_t old_num, size_t num, 56 const char *file, int line); 57 void *CRYPTO_secure_malloc(size_t num, const char *file, int line); 58 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line); 59 void CRYPTO_secure_free(void *ptr, const char *file, int line); 60 void CRYPTO_secure_clear_free(void *ptr, size_t num, 61 const char *file, int line); 62 int CRYPTO_secure_allocated(const void *ptr); 63 void OPENSSL_cleanse(void *ptr, size_t len); 64 65 unsigned char *OPENSSL_hexstr2buf(const char *str, long *buflen); 66 67 OSSL_CORE_BIO *BIO_new_file(const char *filename, const char *mode); 68 OSSL_CORE_BIO *BIO_new_membuf(const void *buf, int len); 69 int BIO_read_ex(OSSL_CORE_BIO *bio, void *data, size_t data_len, 70 size_t *bytes_read); 71 int BIO_write_ex(OSSL_CORE_BIO *bio, const void *data, size_t data_len, 72 size_t *written); 73 int BIO_up_ref(OSSL_CORE_BIO *bio); 74 int BIO_free(OSSL_CORE_BIO *bio); 75 int BIO_vprintf(OSSL_CORE_BIO *bio, const char *format, va_list args); 76 int BIO_vsnprintf(char *buf, size_t n, const char *fmt, va_list args); 77 78 void OSSL_SELF_TEST_set_callback(OSSL_LIB_CTX *libctx, OSSL_CALLBACK *cb, 79 void *cbarg); 80 81 size_t get_entropy(const OSSL_CORE_HANDLE *handle, 82 unsigned char **pout, int entropy, 83 size_t min_len, size_t max_len); 84 void cleanup_entropy(const OSSL_CORE_HANDLE *handle, 85 unsigned char *buf, size_t len); 86 size_t get_nonce(const OSSL_CORE_HANDLE *handle, 87 unsigned char **pout, size_t min_len, size_t max_len, 88 const void *salt, size_t salt_len); 89 void cleanup_nonce(const OSSL_CORE_HANDLE *handle, 90 unsigned char *buf, size_t len); 91 92 /* Functions for querying the providers in the application library context */ 93 int provider_register_child_cb(const OSSL_CORE_HANDLE *handle, 94 int (*create_cb)(const OSSL_CORE_HANDLE *provider, 95 void *cbdata), 96 int (*remove_cb)(const OSSL_CORE_HANDLE *provider, 97 void *cbdata), 98 int (*global_props_cb)(const char *props, void *cbdata), 99 void *cbdata); 100 void provider_deregister_child_cb(const OSSL_CORE_HANDLE *handle); 101 const char *provider_name(const OSSL_CORE_HANDLE *prov); 102 void *provider_get0_provider_ctx(const OSSL_CORE_HANDLE *prov); 103 const OSSL_DISPATCH *provider_get0_dispatch(const OSSL_CORE_HANDLE *prov); 104 int provider_up_ref(const OSSL_CORE_HANDLE *prov, int activate); 105 int provider_free(const OSSL_CORE_HANDLE *prov, int deactivate); 106 107 /* Functions offered by the provider to libcrypto */ 108 void provider_teardown(void *provctx); 109 const OSSL_ITEM *provider_gettable_params(void *provctx); 110 int provider_get_params(void *provctx, OSSL_PARAM params[]); 111 const OSSL_ALGORITHM *provider_query_operation(void *provctx, 112 int operation_id, 113 const int *no_store); 114 void provider_unquery_operation(void *provctx, int operation_id, 115 const OSSL_ALGORITHM *algs); 116 const OSSL_ITEM *provider_get_reason_strings(void *provctx); 117 int provider_get_capabilities(void *provctx, const char *capability, 118 OSSL_CALLBACK *cb, void *arg); 119 int provider_self_test(void *provctx); 120 121=head1 DESCRIPTION 122 123All "functions" mentioned here are passed as function pointers between 124F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays, in the call 125of the provider initialization function. See L<provider(7)/Provider> 126for a description of the initialization function. They are known as "upcalls". 127 128All these "functions" have a corresponding function type definition 129named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the 130function pointer from a B<OSSL_DISPATCH> element named 131B<OSSL_FUNC_{name}>. 132For example, the "function" core_gettable_params() has these: 133 134 typedef OSSL_PARAM * 135 (OSSL_FUNC_core_gettable_params_fn)(const OSSL_CORE_HANDLE *handle); 136 static ossl_inline OSSL_NAME_core_gettable_params_fn 137 OSSL_FUNC_core_gettable_params(const OSSL_DISPATCH *opf); 138 139B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as 140macros in L<openssl-core_dispatch.h(7)>, as follows: 141 142For I<in> (the B<OSSL_DISPATCH> array passed from F<libcrypto> to the 143provider): 144 145 core_gettable_params OSSL_FUNC_CORE_GETTABLE_PARAMS 146 core_get_params OSSL_FUNC_CORE_GET_PARAMS 147 core_thread_start OSSL_FUNC_CORE_THREAD_START 148 core_get_libctx OSSL_FUNC_CORE_GET_LIBCTX 149 core_new_error OSSL_FUNC_CORE_NEW_ERROR 150 core_set_error_debug OSSL_FUNC_CORE_SET_ERROR_DEBUG 151 core_vset_error OSSL_FUNC_CORE_VSET_ERROR 152 core_obj_add_sigid OSSL_FUNC_CORE_OBJ_ADD_SIGID 153 core_obj_create OSSL_FUNC_CORE_OBJ_CREATE 154 CRYPTO_malloc OSSL_FUNC_CRYPTO_MALLOC 155 CRYPTO_zalloc OSSL_FUNC_CRYPTO_ZALLOC 156 CRYPTO_memdup OSSL_FUNC_CRYPTO_MEMDUP 157 CRYPTO_strdup OSSL_FUNC_CRYPTO_STRDUP 158 CRYPTO_strndup OSSL_FUNC_CRYPTO_STRNDUP 159 CRYPTO_free OSSL_FUNC_CRYPTO_FREE 160 CRYPTO_clear_free OSSL_FUNC_CRYPTO_CLEAR_FREE 161 CRYPTO_realloc OSSL_FUNC_CRYPTO_REALLOC 162 CRYPTO_clear_realloc OSSL_FUNC_CRYPTO_CLEAR_REALLOC 163 CRYPTO_secure_malloc OSSL_FUNC_CRYPTO_SECURE_MALLOC 164 CRYPTO_secure_zalloc OSSL_FUNC_CRYPTO_SECURE_ZALLOC 165 CRYPTO_secure_free OSSL_FUNC_CRYPTO_SECURE_FREE 166 CRYPTO_secure_clear_free OSSL_FUNC_CRYPTO_SECURE_CLEAR_FREE 167 CRYPTO_secure_allocated OSSL_FUNC_CRYPTO_SECURE_ALLOCATED 168 BIO_new_file OSSL_FUNC_BIO_NEW_FILE 169 BIO_new_mem_buf OSSL_FUNC_BIO_NEW_MEMBUF 170 BIO_read_ex OSSL_FUNC_BIO_READ_EX 171 BIO_write_ex OSSL_FUNC_BIO_WRITE_EX 172 BIO_up_ref OSSL_FUNC_BIO_UP_REF 173 BIO_free OSSL_FUNC_BIO_FREE 174 BIO_vprintf OSSL_FUNC_BIO_VPRINTF 175 BIO_vsnprintf OSSL_FUNC_BIO_VSNPRINTF 176 BIO_puts OSSL_FUNC_BIO_PUTS 177 BIO_gets OSSL_FUNC_BIO_GETS 178 BIO_ctrl OSSL_FUNC_BIO_CTRL 179 OPENSSL_cleanse OSSL_FUNC_OPENSSL_CLEANSE 180 OSSL_SELF_TEST_set_callback OSSL_FUNC_SELF_TEST_CB 181 ossl_rand_get_entropy OSSL_FUNC_GET_ENTROPY 182 ossl_rand_cleanup_entropy OSSL_FUNC_CLEANUP_ENTROPY 183 ossl_rand_get_nonce OSSL_FUNC_GET_NONCE 184 ossl_rand_cleanup_nonce OSSL_FUNC_CLEANUP_NONCE 185 provider_register_child_cb OSSL_FUNC_PROVIDER_REGISTER_CHILD_CB 186 provider_deregister_child_cb OSSL_FUNC_PROVIDER_DEREGISTER_CHILD_CB 187 provider_name OSSL_FUNC_PROVIDER_NAME 188 provider_get0_provider_ctx OSSL_FUNC_PROVIDER_GET0_PROVIDER_CTX 189 provider_get0_dispatch OSSL_FUNC_PROVIDER_GET0_DISPATCH 190 provider_up_ref OSSL_FUNC_PROVIDER_UP_REF 191 provider_free OSSL_FUNC_PROVIDER_FREE 192 193For I<*out> (the B<OSSL_DISPATCH> array passed from the provider to 194F<libcrypto>): 195 196 provider_teardown OSSL_FUNC_PROVIDER_TEARDOWN 197 provider_gettable_params OSSL_FUNC_PROVIDER_GETTABLE_PARAMS 198 provider_get_params OSSL_FUNC_PROVIDER_GET_PARAMS 199 provider_query_operation OSSL_FUNC_PROVIDER_QUERY_OPERATION 200 provider_unquery_operation OSSL_FUNC_PROVIDER_UNQUERY_OPERATION 201 provider_get_reason_strings OSSL_FUNC_PROVIDER_GET_REASON_STRINGS 202 provider_get_capabilities OSSL_FUNC_PROVIDER_GET_CAPABILITIES 203 provider_self_test OSSL_FUNC_PROVIDER_SELF_TEST 204 205=head2 Core functions 206 207core_gettable_params() returns a constant array of descriptor 208B<OSSL_PARAM>, for parameters that core_get_params() can handle. 209 210core_get_params() retrieves parameters from the core for the given I<handle>. 211See L</Core parameters> below for a description of currently known 212parameters. 213 214The core_thread_start() function informs the core that the provider has stated 215an interest in the current thread. The core will inform the provider when the 216thread eventually stops. It must be passed the I<handle> for this provider, as 217well as a callback I<handfn> which will be called when the thread stops. The 218callback will subsequently be called, with the supplied argument I<arg>, from 219the thread that is stopping and gets passed the provider context as an 220argument. This may be useful to perform thread specific clean up such as 221freeing thread local variables. 222 223core_get_libctx() retrieves the library context in which the library 224object for the current provider is stored, accessible through the I<handle>. 225This may sometimes be useful if the provider wishes to store a 226reference to its context in the same library context. 227 228core_new_error(), core_set_error_debug() and core_vset_error() are 229building blocks for reporting an error back to the core, with 230reference to the I<handle>. 231 232=over 4 233 234=item core_new_error() 235 236allocates a new thread specific error record. 237 238This corresponds to the OpenSSL function L<ERR_new(3)>. 239 240=item core_set_error_debug() 241 242sets debugging information in the current thread specific error 243record. 244The debugging information includes the name of the file I<file>, the 245line I<line> and the function name I<func> where the error occurred. 246 247This corresponds to the OpenSSL function L<ERR_set_debug(3)>. 248 249=item core_vset_error() 250 251sets the I<reason> for the error, along with any addition data. 252The I<reason> is a number defined by the provider and used to index 253the reason strings table that's returned by 254provider_get_reason_strings(). 255The additional data is given as a format string I<fmt> and a set of 256arguments I<args>, which are treated in the same manner as with 257BIO_vsnprintf(). 258I<file> and I<line> may also be passed to indicate exactly where the 259error occurred or was reported. 260 261This corresponds to the OpenSSL function L<ERR_vset_error(3)>. 262 263=back 264 265The core_obj_create() function registers a new OID and associated short name 266I<sn> and long name I<ln> for the given I<handle>. It is similar to the OpenSSL 267function L<OBJ_create(3)> except that it returns 1 on success or 0 on failure. 268It will treat as success the case where the OID already exists (even if the 269short name I<sn> or long name I<ln> provided as arguments differ from those 270associated with the existing OID, in which case the new names are not 271associated). 272This function is not thread safe. 273 274The core_obj_add_sigid() function registers a new composite signature algorithm 275(I<sign_name>) consisting of an underlying signature algorithm (I<pkey_name>) 276and digest algorithm (I<digest_name>) for the given I<handle>. It assumes that 277the OIDs for the composite signature algorithm as well as for the underlying 278signature and digest algorithms are either already known to OpenSSL or have been 279registered via a call to core_obj_create(). It corresponds to the OpenSSL 280function L<OBJ_add_sigid(3)>, except that the objects are identified by name 281rather than a numeric NID. Any name (OID, short name or long name) can be used 282to identify the object. It will treat as success the case where the composite 283signature algorithm already exists (even if registered against a different 284underlying signature or digest algorithm). It returns 1 on success or 0 on 285failure. 286This function is not thread safe. 287 288CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_memdup(), CRYPTO_strdup(), 289CRYPTO_strndup(), CRYPTO_free(), CRYPTO_clear_free(), 290CRYPTO_realloc(), CRYPTO_clear_realloc(), CRYPTO_secure_malloc(), 291CRYPTO_secure_zalloc(), CRYPTO_secure_free(), 292CRYPTO_secure_clear_free(), CRYPTO_secure_allocated(), 293BIO_new_file(), BIO_new_mem_buf(), BIO_read_ex(), BIO_write_ex(), BIO_up_ref(), 294BIO_free(), BIO_vprintf(), BIO_vsnprintf(), BIO_gets(), BIO_puts(), 295BIO_ctrl(), OPENSSL_cleanse() and 296OPENSSL_hexstr2buf() correspond exactly to the public functions with 297the same name. As a matter of fact, the pointers in the B<OSSL_DISPATCH> 298array are typically direct pointers to those public functions. Note that the BIO 299functions take an B<OSSL_CORE_BIO> type rather than the standard B<BIO> 300type. This is to ensure that a provider does not mix BIOs from the core 301with BIOs used on the provider side (the two are not compatible). 302OSSL_SELF_TEST_set_callback() is used to set an optional callback that can be 303passed into a provider. This may be ignored by a provider. 304 305get_entropy() retrieves seeding material from the operating system. 306The seeding material will have at least I<entropy> bytes of randomness and the 307output will have at least I<min_len> and at most I<max_len> bytes. 308The buffer address is stored in I<*pout> and the buffer length is 309returned to the caller. On error, zero is returned. 310 311cleanup_entropy() is used to clean up and free the buffer returned by 312get_entropy(). The entropy pointer returned by get_entropy() is passed in 313B<buf> and its length in B<len>. 314 315get_nonce() retrieves a nonce using the passed I<salt> parameter 316of length I<salt_len> and operating system specific information. 317The I<salt> should contain uniquely identifying information and this is 318included, in an unspecified manner, as part of the output. 319The output is stored in a buffer which contrains at least I<min_len> and at 320most I<max_len> bytes. The buffer address is stored in I<*pout> and the 321buffer length returned to the caller. On error, zero is returned. 322 323cleanup_nonce() is used to clean up and free the buffer returned by 324get_nonce(). The nonce pointer returned by get_nonce() is passed in 325B<buf> and its length in B<len>. 326 327provider_register_child_cb() registers callbacks for being informed about the 328loading and unloading of providers in the application's library context. 329I<handle> is this provider's handle and I<cbdata> is this provider's data 330that will be passed back to the callbacks. It returns 1 on success or 0 331otherwise. These callbacks may be called while holding locks in libcrypto. In 332order to avoid deadlocks the callback implementation must not be long running 333and must not call other OpenSSL API functions or upcalls. 334 335I<create_cb> is a callback that will be called when a new provider is loaded 336into the application's library context. It is also called for any providers that 337are already loaded at the point that this callback is registered. The callback 338is passed the handle being used for the new provider being loadded and this 339provider's data in I<cbdata>. It should return 1 on success or 0 on failure. 340 341I<remove_cb> is a callback that will be called when a new provider is unloaded 342from the application's library context. It is passed the handle being used for 343the provider being unloaded and this provider's data in I<cbdata>. It should 344return 1 on success or 0 on failure. 345 346I<global_props_cb> is a callback that will be called when the global properties 347from the parent library context are changed. It should return 1 on success 348or 0 on failure. 349 350provider_deregister_child_cb() unregisters callbacks previously registered via 351provider_register_child_cb(). If provider_register_child_cb() has been called 352then provider_deregister_child_cb() should be called at or before the point that 353this provider's teardown function is called. 354 355provider_name() returns a string giving the name of the provider identified by 356I<handle>. 357 358provider_get0_provider_ctx() returns the provider context that is associated 359with the provider identified by I<prov>. 360 361provider_get0_dispatch() gets the dispatch table registered by the provider 362identified by I<prov> when it initialised. 363 364provider_up_ref() increments the reference count on the provider I<prov>. If 365I<activate> is nonzero then the provider is also loaded if it is not already 366loaded. It returns 1 on success or 0 on failure. 367 368provider_free() decrements the reference count on the provider I<prov>. If 369I<deactivate> is nonzero then the provider is also unloaded if it is not 370already loaded. It returns 1 on success or 0 on failure. 371 372=head2 Provider functions 373 374provider_teardown() is called when a provider is shut down and removed 375from the core's provider store. 376It must free the passed I<provctx>. 377 378provider_gettable_params() should return a constant array of 379descriptor B<OSSL_PARAM>, for parameters that provider_get_params() 380can handle. 381 382provider_get_params() should process the B<OSSL_PARAM> array 383I<params>, setting the values of the parameters it understands. 384 385provider_query_operation() should return a constant B<OSSL_ALGORITHM> 386that corresponds to the given I<operation_id>. 387It should indicate if the core may store a reference to this array by 388setting I<*no_store> to 0 (core may store a reference) or 1 (core may 389not store a reference). 390 391provider_unquery_operation() informs the provider that the result of a 392provider_query_operation() is no longer directly required and that the function 393pointers have been copied. The I<operation_id> should match that passed to 394provider_query_operation() and I<algs> should be its return value. 395 396provider_get_reason_strings() should return a constant B<OSSL_ITEM> 397array that provides reason strings for reason codes the provider may 398use when reporting errors using core_put_error(). 399 400The provider_get_capabilities() function should call the callback I<cb> passing 401it a set of B<OSSL_PARAM>s and the caller supplied argument I<arg>. The 402B<OSSL_PARAM>s should provide details about the capability with the name given 403in the I<capability> argument relevant for the provider context I<provctx>. If a 404provider supports multiple capabilities with the given name then it may call the 405callback multiple times (one for each capability). Capabilities can be useful for 406describing the services that a provider can offer. For further details see the 407L</CAPABILITIES> section below. It should return 1 on success or 0 on error. 408 409The provider_self_test() function should perform known answer tests on a subset 410of the algorithms that it uses, and may also verify the integrity of the 411provider module. It should return 1 on success or 0 on error. It will return 1 412if this function is not used. 413 414None of these functions are mandatory, but a provider is fairly 415useless without at least provider_query_operation(), and 416provider_gettable_params() is fairly useless if not accompanied by 417provider_get_params(). 418 419=head2 Provider parameters 420 421provider_get_params() can return the following provider parameters to the core: 422 423=over 4 424 425=item "name" (B<OSSL_PROV_PARAM_NAME>) <UTF8 string ptr> 426 427This points to a string that should give a unique name for the provider. 428 429=item "version" (B<OSSL_PROV_PARAM_VERSION>) <UTF8 string ptr> 430 431This points to a string that is a version number associated with this provider. 432OpenSSL in-built providers use OPENSSL_VERSION_STR, but this may be different 433for any third party provider. This string is for informational purposes only. 434 435=item "buildinfo" (B<OSSL_PROV_PARAM_BUILDINFO>) <UTF8 string ptr> 436 437This points to a string that is a build information associated with this provider. 438OpenSSL in-built providers use OPENSSL_FULL_VERSION_STR, but this may be 439different for any third party provider. 440 441=item "status" (B<OSSL_PROV_PARAM_STATUS>) <unsigned integer> 442 443This returns 0 if the provider has entered an error state, otherwise it returns 4441. 445 446=back 447 448provider_gettable_params() should return the above parameters. 449 450 451=head2 Core parameters 452 453core_get_params() can retrieve the following core parameters for each provider: 454 455=over 4 456 457=item "openssl-version" (B<OSSL_PROV_PARAM_CORE_VERSION>) <UTF8 string ptr> 458 459This points to the OpenSSL libraries' full version string, i.e. the string 460expanded from the macro B<OPENSSL_VERSION_STR>. 461 462=item "provider-name" (B<OSSL_PROV_PARAM_CORE_PROV_NAME>) <UTF8 string ptr> 463 464This points to the OpenSSL libraries' idea of what the calling provider is named. 465 466=item "module-filename" (B<OSSL_PROV_PARAM_CORE_MODULE_FILENAME>) <UTF8 string ptr> 467 468This points to a string containing the full filename of the providers 469module file. 470 471=back 472 473Additionally, provider specific configuration parameters from the 474config file are available, in dotted name form. 475The dotted name form is a concatenation of section names and final 476config command name separated by periods. 477 478For example, let's say we have the following config example: 479 480 config_diagnostics = 1 481 openssl_conf = openssl_init 482 483 [openssl_init] 484 providers = providers_sect 485 486 [providers_sect] 487 foo = foo_sect 488 489 [foo_sect] 490 activate = 1 491 data1 = 2 492 data2 = str 493 more = foo_more 494 495 [foo_more] 496 data3 = foo,bar 497 498The provider will have these additional parameters available: 499 500=over 4 501 502=item "activate" 503 504pointing at the string "1" 505 506=item "data1" 507 508pointing at the string "2" 509 510=item "data2" 511 512pointing at the string "str" 513 514=item "more.data3" 515 516pointing at the string "foo,bar" 517 518=back 519 520For more information on handling parameters, see L<OSSL_PARAM(3)> as 521L<OSSL_PARAM_int(3)>. 522 523=head1 CAPABILITIES 524 525Capabilities describe some of the services that a provider can offer. 526Applications can query the capabilities to discover those services. 527 528=head3 "TLS-GROUP" Capability 529 530The "TLS-GROUP" capability can be queried by libssl to discover the list of 531TLS groups that a provider can support. Each group supported can be used for 532I<key exchange> (KEX) or I<key encapsulation method> (KEM) during a TLS 533handshake. 534TLS clients can advertise the list of TLS groups they support in the 535supported_groups extension, and TLS servers can select a group from the offered 536list that they also support. In this way a provider can add to the list of 537groups that libssl already supports with additional ones. 538 539Each TLS group that a provider supports should be described via the callback 540passed in through the provider_get_capabilities function. Each group should have 541the following details supplied (all are mandatory, except 542B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>): 543 544=over 4 545 546=item "tls-group-name" (B<OSSL_CAPABILITY_TLS_GROUP_NAME>) <UTF8 string> 547 548The name of the group as given in the IANA TLS Supported Groups registry 549L<https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-8>. 550 551=item "tls-group-name-internal" (B<OSSL_CAPABILITY_TLS_GROUP_NAME_INTERNAL>) <UTF8 string> 552 553The name of the group as known by the provider. This could be the same as the 554"tls-group-name", but does not have to be. 555 556=item "tls-group-id" (B<OSSL_CAPABILITY_TLS_GROUP_ID>) <unsigned integer> 557 558The TLS group id value as given in the IANA TLS Supported Groups registry. 559 560=item "tls-group-alg" (B<OSSL_CAPABILITY_TLS_GROUP_ALG>) <UTF8 string> 561 562The name of a Key Management algorithm that the provider offers and that should 563be used with this group. Keys created should be able to support I<key exchange> 564or I<key encapsulation method> (KEM), as implied by the optional 565B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM> flag. 566The algorithm must support key and parameter generation as well as the 567key/parameter generation parameter, B<OSSL_PKEY_PARAM_GROUP_NAME>. The group 568name given via "tls-group-name-internal" above will be passed via 569B<OSSL_PKEY_PARAM_GROUP_NAME> when libssl wishes to generate keys/parameters. 570 571=item "tls-group-sec-bits" (B<OSSL_CAPABILITY_TLS_GROUP_SECURITY_BITS>) <unsigned integer> 572 573The number of bits of security offered by keys in this group. The number of bits 574should be comparable with the ones given in table 2 and 3 of the NIST SP800-57 575document. 576 577=item "tls-group-is-kem" (B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>) <unsigned integer> 578 579Boolean flag to describe if the group should be used in I<key exchange> (KEX) 580mode (0, default) or in I<key encapsulation method> (KEM) mode (1). 581 582This parameter is optional: if not specified, KEX mode is assumed as the default 583mode for the group. 584 585In KEX mode, in a typical Diffie-Hellman fashion, both sides execute I<keygen> 586then I<derive> against the peer public key. To operate in KEX mode, the group 587implementation must support the provider functions as described in 588L<provider-keyexch(7)>. 589 590In KEM mode, the client executes I<keygen> and sends its public key, the server 591executes I<encapsulate> using the client's public key and sends back the 592resulting I<ciphertext>, finally the client executes I<decapsulate> to retrieve 593the same I<shared secret> generated by the server's I<encapsulate>. To operate 594in KEM mode, the group implementation must support the provider functions as 595described in L<provider-kem(7)>. 596 597Both in KEX and KEM mode, the resulting I<shared secret> is then used according 598to the protocol specification. 599 600=item "tls-min-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_TLS>) <integer> 601 602=item "tls-max-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_TLS>) <integer> 603 604=item "tls-min-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_DTLS>) <integer> 605 606=item "tls-max-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_DTLS>) <integer> 607 608These parameters can be used to describe the minimum and maximum TLS and DTLS 609versions supported by the group. The values equate to the on-the-wire encoding 610of the various TLS versions. For example TLSv1.3 is 0x0304 (772 decimal), and 611TLSv1.2 is 0x0303 (771 decimal). A 0 indicates that there is no defined minimum 612or maximum. A -1 indicates that the group should not be used in that protocol. 613 614=back 615 616=head1 EXAMPLES 617 618This is an example of a simple provider made available as a 619dynamically loadable module. 620It implements the fictitious algorithm C<FOO> for the fictitious 621operation C<BAR>. 622 623 #include <malloc.h> 624 #include <openssl/core.h> 625 #include <openssl/core_dispatch.h> 626 627 /* Errors used in this provider */ 628 #define E_MALLOC 1 629 630 static const OSSL_ITEM reasons[] = { 631 { E_MALLOC, "memory allocation failure" }. 632 { 0, NULL } /* Termination */ 633 }; 634 635 /* 636 * To ensure we get the function signature right, forward declare 637 * them using function types provided by openssl/core_dispatch.h 638 */ 639 OSSL_FUNC_bar_newctx_fn foo_newctx; 640 OSSL_FUNC_bar_freectx_fn foo_freectx; 641 OSSL_FUNC_bar_init_fn foo_init; 642 OSSL_FUNC_bar_update_fn foo_update; 643 OSSL_FUNC_bar_final_fn foo_final; 644 645 OSSL_FUNC_provider_query_operation_fn p_query; 646 OSSL_FUNC_provider_get_reason_strings_fn p_reasons; 647 OSSL_FUNC_provider_teardown_fn p_teardown; 648 649 OSSL_provider_init_fn OSSL_provider_init; 650 651 OSSL_FUNC_core_put_error *c_put_error = NULL; 652 653 /* Provider context */ 654 struct prov_ctx_st { 655 OSSL_CORE_HANDLE *handle; 656 } 657 658 /* operation context for the algorithm FOO */ 659 struct foo_ctx_st { 660 struct prov_ctx_st *provctx; 661 int b; 662 }; 663 664 static void *foo_newctx(void *provctx) 665 { 666 struct foo_ctx_st *fooctx = malloc(sizeof(*fooctx)); 667 668 if (fooctx != NULL) 669 fooctx->provctx = provctx; 670 else 671 c_put_error(provctx->handle, E_MALLOC, __FILE__, __LINE__); 672 return fooctx; 673 } 674 675 static void foo_freectx(void *fooctx) 676 { 677 free(fooctx); 678 } 679 680 static int foo_init(void *vfooctx) 681 { 682 struct foo_ctx_st *fooctx = vfooctx; 683 684 fooctx->b = 0x33; 685 } 686 687 static int foo_update(void *vfooctx, unsigned char *in, size_t inl) 688 { 689 struct foo_ctx_st *fooctx = vfooctx; 690 691 /* did you expect something serious? */ 692 if (inl == 0) 693 return 1; 694 for (; inl-- > 0; in++) 695 *in ^= fooctx->b; 696 return 1; 697 } 698 699 static int foo_final(void *vfooctx) 700 { 701 struct foo_ctx_st *fooctx = vfooctx; 702 703 fooctx->b = 0x66; 704 } 705 706 static const OSSL_DISPATCH foo_fns[] = { 707 { OSSL_FUNC_BAR_NEWCTX, (void (*)(void))foo_newctx }, 708 { OSSL_FUNC_BAR_FREECTX, (void (*)(void))foo_freectx }, 709 { OSSL_FUNC_BAR_INIT, (void (*)(void))foo_init }, 710 { OSSL_FUNC_BAR_UPDATE, (void (*)(void))foo_update }, 711 { OSSL_FUNC_BAR_FINAL, (void (*)(void))foo_final }, 712 { 0, NULL } 713 }; 714 715 static const OSSL_ALGORITHM bars[] = { 716 { "FOO", "provider=chumbawamba", foo_fns }, 717 { NULL, NULL, NULL } 718 }; 719 720 static const OSSL_ALGORITHM *p_query(void *provctx, int operation_id, 721 int *no_store) 722 { 723 switch (operation_id) { 724 case OSSL_OP_BAR: 725 return bars; 726 } 727 return NULL; 728 } 729 730 static const OSSL_ITEM *p_reasons(void *provctx) 731 { 732 return reasons; 733 } 734 735 static void p_teardown(void *provctx) 736 { 737 free(provctx); 738 } 739 740 static const OSSL_DISPATCH prov_fns[] = { 741 { OSSL_FUNC_PROVIDER_TEARDOWN, (void (*)(void))p_teardown }, 742 { OSSL_FUNC_PROVIDER_QUERY_OPERATION, (void (*)(void))p_query }, 743 { OSSL_FUNC_PROVIDER_GET_REASON_STRINGS, (void (*)(void))p_reasons }, 744 { 0, NULL } 745 }; 746 747 int OSSL_provider_init(const OSSL_CORE_HANDLE *handle, 748 const OSSL_DISPATCH *in, 749 const OSSL_DISPATCH **out, 750 void **provctx) 751 { 752 struct prov_ctx_st *pctx = NULL; 753 754 for (; in->function_id != 0; in++) 755 switch (in->function_id) { 756 case OSSL_FUNC_CORE_PUT_ERROR: 757 c_put_error = OSSL_FUNC_core_put_error(in); 758 break; 759 } 760 761 *out = prov_fns; 762 763 if ((pctx = malloc(sizeof(*pctx))) == NULL) { 764 /* 765 * ALEA IACTA EST, if the core retrieves the reason table 766 * regardless, that string will be displayed, otherwise not. 767 */ 768 c_put_error(handle, E_MALLOC, __FILE__, __LINE__); 769 return 0; 770 } 771 pctx->handle = handle; 772 return 1; 773 } 774 775This relies on a few things existing in F<openssl/core_dispatch.h>: 776 777 #define OSSL_OP_BAR 4711 778 779 #define OSSL_FUNC_BAR_NEWCTX 1 780 typedef void *(OSSL_FUNC_bar_newctx_fn)(void *provctx); 781 static ossl_inline OSSL_FUNC_bar_newctx(const OSSL_DISPATCH *opf) 782 { return (OSSL_FUNC_bar_newctx_fn *)opf->function; } 783 784 #define OSSL_FUNC_BAR_FREECTX 2 785 typedef void (OSSL_FUNC_bar_freectx_fn)(void *ctx); 786 static ossl_inline OSSL_FUNC_bar_newctx(const OSSL_DISPATCH *opf) 787 { return (OSSL_FUNC_bar_freectx_fn *)opf->function; } 788 789 #define OSSL_FUNC_BAR_INIT 3 790 typedef void *(OSSL_FUNC_bar_init_fn)(void *ctx); 791 static ossl_inline OSSL_FUNC_bar_init(const OSSL_DISPATCH *opf) 792 { return (OSSL_FUNC_bar_init_fn *)opf->function; } 793 794 #define OSSL_FUNC_BAR_UPDATE 4 795 typedef void *(OSSL_FUNC_bar_update_fn)(void *ctx, 796 unsigned char *in, size_t inl); 797 static ossl_inline OSSL_FUNC_bar_update(const OSSL_DISPATCH *opf) 798 { return (OSSL_FUNC_bar_update_fn *)opf->function; } 799 800 #define OSSL_FUNC_BAR_FINAL 5 801 typedef void *(OSSL_FUNC_bar_final_fn)(void *ctx); 802 static ossl_inline OSSL_FUNC_bar_final(const OSSL_DISPATCH *opf) 803 { return (OSSL_FUNC_bar_final_fn *)opf->function; } 804 805=head1 SEE ALSO 806 807L<provider(7)> 808 809=head1 HISTORY 810 811The concept of providers and everything surrounding them was 812introduced in OpenSSL 3.0. 813 814=head1 COPYRIGHT 815 816Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved. 817 818Licensed under the Apache License 2.0 (the "License"). You may not use 819this file except in compliance with the License. You can obtain a copy 820in the file LICENSE in the source distribution or at 821L<https://www.openssl.org/source/license.html>. 822 823=cut 824