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 core context in which the library
224object for the current provider is stored, accessible through the I<handle>.
225This function is useful only for built-in providers such as the default
226provider. Never cast this to OSSL_LIB_CTX in a provider that is not
227built-in as the OSSL_LIB_CTX of the library loading the provider might be
228a completely different structure than the OSSL_LIB_CTX of the library the
229provider is linked to. Use  L<OSSL_LIB_CTX_new_child(3)> instead to obtain
230a proper library context that is linked to the application library context.
231
232core_new_error(), core_set_error_debug() and core_vset_error() are
233building blocks for reporting an error back to the core, with
234reference to the I<handle>.
235
236=over 4
237
238=item core_new_error()
239
240allocates a new thread specific error record.
241
242This corresponds to the OpenSSL function L<ERR_new(3)>.
243
244=item core_set_error_debug()
245
246sets debugging information in the current thread specific error
247record.
248The debugging information includes the name of the file I<file>, the
249line I<line> and the function name I<func> where the error occurred.
250
251This corresponds to the OpenSSL function L<ERR_set_debug(3)>.
252
253=item core_vset_error()
254
255sets the I<reason> for the error, along with any addition data.
256The I<reason> is a number defined by the provider and used to index
257the reason strings table that's returned by
258provider_get_reason_strings().
259The additional data is given as a format string I<fmt> and a set of
260arguments I<args>, which are treated in the same manner as with
261BIO_vsnprintf().
262I<file> and I<line> may also be passed to indicate exactly where the
263error occurred or was reported.
264
265This corresponds to the OpenSSL function L<ERR_vset_error(3)>.
266
267=back
268
269The core_obj_create() function registers a new OID and associated short name
270I<sn> and long name I<ln> for the given I<handle>. It is similar to the OpenSSL
271function L<OBJ_create(3)> except that it returns 1 on success or 0 on failure.
272It will treat as success the case where the OID already exists (even if the
273short name I<sn> or long name I<ln> provided as arguments differ from those
274associated with the existing OID, in which case the new names are not
275associated).
276
277The core_obj_add_sigid() function registers a new composite signature algorithm
278(I<sign_name>) consisting of an underlying signature algorithm (I<pkey_name>)
279and digest algorithm (I<digest_name>) for the given I<handle>. It assumes that
280the OIDs for the composite signature algorithm as well as for the underlying
281signature and digest algorithms are either already known to OpenSSL or have been
282registered via a call to core_obj_create(). It corresponds to the OpenSSL
283function L<OBJ_add_sigid(3)>, except that the objects are identified by name
284rather than a numeric NID. Any name (OID, short name or long name) can be used
285to identify the object. It will treat as success the case where the composite
286signature algorithm already exists (even if registered against a different
287underlying signature or digest algorithm). For I<digest_name>, NULL or an
288empty string is permissible for signature algorithms that do not need a digest
289to operate correctly. The function returns 1 on success or 0 on failure.
290
291CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_memdup(), CRYPTO_strdup(),
292CRYPTO_strndup(), CRYPTO_free(), CRYPTO_clear_free(),
293CRYPTO_realloc(), CRYPTO_clear_realloc(), CRYPTO_secure_malloc(),
294CRYPTO_secure_zalloc(), CRYPTO_secure_free(),
295CRYPTO_secure_clear_free(), CRYPTO_secure_allocated(),
296BIO_new_file(), BIO_new_mem_buf(), BIO_read_ex(), BIO_write_ex(), BIO_up_ref(),
297BIO_free(), BIO_vprintf(), BIO_vsnprintf(), BIO_gets(), BIO_puts(),
298BIO_ctrl(), OPENSSL_cleanse() and
299OPENSSL_hexstr2buf() correspond exactly to the public functions with
300the same name.  As a matter of fact, the pointers in the B<OSSL_DISPATCH>
301array are typically direct pointers to those public functions. Note that the BIO
302functions take an B<OSSL_CORE_BIO> type rather than the standard B<BIO>
303type. This is to ensure that a provider does not mix BIOs from the core
304with BIOs used on the provider side (the two are not compatible).
305OSSL_SELF_TEST_set_callback() is used to set an optional callback that can be
306passed into a provider. This may be ignored by a provider.
307
308get_entropy() retrieves seeding material from the operating system.
309The seeding material will have at least I<entropy> bytes of randomness and the
310output will have at least I<min_len> and at most I<max_len> bytes.
311The buffer address is stored in I<*pout> and the buffer length is
312returned to the caller.  On error, zero is returned.
313
314cleanup_entropy() is used to clean up and free the buffer returned by
315get_entropy().  The entropy pointer returned by get_entropy() is passed in
316B<buf> and its length in B<len>.
317
318get_nonce() retrieves a nonce using the passed I<salt> parameter
319of length I<salt_len> and operating system specific information.
320The I<salt> should contain uniquely identifying information and this is
321included, in an unspecified manner, as part of the output.
322The output is stored in a buffer which contrains at least I<min_len> and at
323most I<max_len> bytes.  The buffer address is stored in I<*pout> and the
324buffer length returned to the caller.  On error, zero is returned.
325
326cleanup_nonce() is used to clean up and free the buffer returned by
327get_nonce().  The nonce pointer returned by get_nonce() is passed in
328B<buf> and its length in B<len>.
329
330provider_register_child_cb() registers callbacks for being informed about the
331loading and unloading of providers in the application's library context.
332I<handle> is this provider's handle and I<cbdata> is this provider's data
333that will be passed back to the callbacks. It returns 1 on success or 0
334otherwise. These callbacks may be called while holding locks in libcrypto. In
335order to avoid deadlocks the callback implementation must not be long running
336and must not call other OpenSSL API functions or upcalls.
337
338I<create_cb> is a callback that will be called when a new provider is loaded
339into the application's library context. It is also called for any providers that
340are already loaded at the point that this callback is registered. The callback
341is passed the handle being used for the new provider being loadded and this
342provider's data in I<cbdata>. It should return 1 on success or 0 on failure.
343
344I<remove_cb> is a callback that will be called when a new provider is unloaded
345from the application's library context. It is passed the handle being used for
346the provider being unloaded and this provider's data in I<cbdata>. It should
347return 1 on success or 0 on failure.
348
349I<global_props_cb> is a callback that will be called when the global properties
350from the parent library context are changed. It should return 1 on success
351or 0 on failure.
352
353provider_deregister_child_cb() unregisters callbacks previously registered via
354provider_register_child_cb(). If provider_register_child_cb() has been called
355then provider_deregister_child_cb() should be called at or before the point that
356this provider's teardown function is called.
357
358provider_name() returns a string giving the name of the provider identified by
359I<handle>.
360
361provider_get0_provider_ctx() returns the provider context that is associated
362with the provider identified by I<prov>.
363
364provider_get0_dispatch() gets the dispatch table registered by the provider
365identified by I<prov> when it initialised.
366
367provider_up_ref() increments the reference count on the provider I<prov>. If
368I<activate> is nonzero then the provider is also loaded if it is not already
369loaded. It returns 1 on success or 0 on failure.
370
371provider_free() decrements the reference count on the provider I<prov>. If
372I<deactivate> is nonzero then the provider is also unloaded if it is not
373already loaded. It returns 1 on success or 0 on failure.
374
375=head2 Provider functions
376
377provider_teardown() is called when a provider is shut down and removed
378from the core's provider store.
379It must free the passed I<provctx>.
380
381provider_gettable_params() should return a constant array of
382descriptor B<OSSL_PARAM>, for parameters that provider_get_params()
383can handle.
384
385provider_get_params() should process the B<OSSL_PARAM> array
386I<params>, setting the values of the parameters it understands.
387
388provider_query_operation() should return a constant B<OSSL_ALGORITHM>
389that corresponds to the given I<operation_id>.
390It should indicate if the core may store a reference to this array by
391setting I<*no_store> to 0 (core may store a reference) or 1 (core may
392not store a reference).
393
394provider_unquery_operation() informs the provider that the result of a
395provider_query_operation() is no longer directly required and that the function
396pointers have been copied.  The I<operation_id> should match that passed to
397provider_query_operation() and I<algs> should be its return value.
398
399provider_get_reason_strings() should return a constant B<OSSL_ITEM>
400array that provides reason strings for reason codes the provider may
401use when reporting errors using core_put_error().
402
403The provider_get_capabilities() function should call the callback I<cb> passing
404it a set of B<OSSL_PARAM>s and the caller supplied argument I<arg>. The
405B<OSSL_PARAM>s should provide details about the capability with the name given
406in the I<capability> argument relevant for the provider context I<provctx>. If a
407provider supports multiple capabilities with the given name then it may call the
408callback multiple times (one for each capability). Capabilities can be useful for
409describing the services that a provider can offer. For further details see the
410L</CAPABILITIES> section below. It should return 1 on success or 0 on error.
411
412The provider_self_test() function should perform known answer tests on a subset
413of the algorithms that it uses, and may also verify the integrity of the
414provider module. It should return 1 on success or 0 on error. It will return 1
415if this function is not used.
416
417None of these functions are mandatory, but a provider is fairly
418useless without at least provider_query_operation(), and
419provider_gettable_params() is fairly useless if not accompanied by
420provider_get_params().
421
422=head2 Provider parameters
423
424provider_get_params() can return the following provider parameters to the core:
425
426=over 4
427
428=item "name" (B<OSSL_PROV_PARAM_NAME>) <UTF8 string ptr>
429
430This points to a string that should give a unique name for the provider.
431
432=item "version" (B<OSSL_PROV_PARAM_VERSION>) <UTF8 string ptr>
433
434This points to a string that is a version number associated with this provider.
435OpenSSL in-built providers use OPENSSL_VERSION_STR, but this may be different
436for any third party provider. This string is for informational purposes only.
437
438=item "buildinfo" (B<OSSL_PROV_PARAM_BUILDINFO>) <UTF8 string ptr>
439
440This points to a string that is a build information associated with this provider.
441OpenSSL in-built providers use OPENSSL_FULL_VERSION_STR, but this may be
442different for any third party provider.
443
444=item "status" (B<OSSL_PROV_PARAM_STATUS>) <unsigned integer>
445
446This returns 0 if the provider has entered an error state, otherwise it returns
4471.
448
449=back
450
451provider_gettable_params() should return the above parameters.
452
453
454=head2 Core parameters
455
456core_get_params() can retrieve the following core parameters for each provider:
457
458=over 4
459
460=item "openssl-version" (B<OSSL_PROV_PARAM_CORE_VERSION>) <UTF8 string ptr>
461
462This points to the OpenSSL libraries' full version string, i.e. the string
463expanded from the macro B<OPENSSL_VERSION_STR>.
464
465=item "provider-name" (B<OSSL_PROV_PARAM_CORE_PROV_NAME>) <UTF8 string ptr>
466
467This points to the OpenSSL libraries' idea of what the calling provider is named.
468
469=item "module-filename" (B<OSSL_PROV_PARAM_CORE_MODULE_FILENAME>) <UTF8 string ptr>
470
471This points to a string containing the full filename of the providers
472module file.
473
474=back
475
476Additionally, provider specific configuration parameters from the
477config file are available, in dotted name form.
478The dotted name form is a concatenation of section names and final
479config command name separated by periods.
480
481For example, let's say we have the following config example:
482
483 config_diagnostics = 1
484 openssl_conf = openssl_init
485
486 [openssl_init]
487 providers = providers_sect
488
489 [providers_sect]
490 foo = foo_sect
491
492 [foo_sect]
493 activate = 1
494 data1 = 2
495 data2 = str
496 more = foo_more
497
498 [foo_more]
499 data3 = foo,bar
500
501The provider will have these additional parameters available:
502
503=over 4
504
505=item "activate"
506
507pointing at the string "1"
508
509=item "data1"
510
511pointing at the string "2"
512
513=item "data2"
514
515pointing at the string "str"
516
517=item "more.data3"
518
519pointing at the string "foo,bar"
520
521=back
522
523For more information on handling parameters, see L<OSSL_PARAM(3)> as
524L<OSSL_PARAM_int(3)>.
525
526=head1 CAPABILITIES
527
528Capabilities describe some of the services that a provider can offer.
529Applications can query the capabilities to discover those services.
530
531=head3 "TLS-GROUP" Capability
532
533The "TLS-GROUP" capability can be queried by libssl to discover the list of
534TLS groups that a provider can support. Each group supported can be used for
535I<key exchange> (KEX) or I<key encapsulation method> (KEM) during a TLS
536handshake.
537TLS clients can advertise the list of TLS groups they support in the
538supported_groups extension, and TLS servers can select a group from the offered
539list that they also support. In this way a provider can add to the list of
540groups that libssl already supports with additional ones.
541
542Each TLS group that a provider supports should be described via the callback
543passed in through the provider_get_capabilities function. Each group should have
544the following details supplied (all are mandatory, except
545B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>):
546
547=over 4
548
549=item "tls-group-name" (B<OSSL_CAPABILITY_TLS_GROUP_NAME>) <UTF8 string>
550
551The name of the group as given in the IANA TLS Supported Groups registry
552L<https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-8>.
553
554=item "tls-group-name-internal" (B<OSSL_CAPABILITY_TLS_GROUP_NAME_INTERNAL>) <UTF8 string>
555
556The name of the group as known by the provider. This could be the same as the
557"tls-group-name", but does not have to be.
558
559=item "tls-group-id" (B<OSSL_CAPABILITY_TLS_GROUP_ID>) <unsigned integer>
560
561The TLS group id value as given in the IANA TLS Supported Groups registry.
562
563=item "tls-group-alg" (B<OSSL_CAPABILITY_TLS_GROUP_ALG>) <UTF8 string>
564
565The name of a Key Management algorithm that the provider offers and that should
566be used with this group. Keys created should be able to support I<key exchange>
567or I<key encapsulation method> (KEM), as implied by the optional
568B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM> flag.
569The algorithm must support key and parameter generation as well as the
570key/parameter generation parameter, B<OSSL_PKEY_PARAM_GROUP_NAME>. The group
571name given via "tls-group-name-internal" above will be passed via
572B<OSSL_PKEY_PARAM_GROUP_NAME> when libssl wishes to generate keys/parameters.
573
574=item "tls-group-sec-bits" (B<OSSL_CAPABILITY_TLS_GROUP_SECURITY_BITS>) <unsigned integer>
575
576The number of bits of security offered by keys in this group. The number of bits
577should be comparable with the ones given in table 2 and 3 of the NIST SP800-57
578document.
579
580=item "tls-group-is-kem" (B<OSSL_CAPABILITY_TLS_GROUP_IS_KEM>) <unsigned integer>
581
582Boolean flag to describe if the group should be used in I<key exchange> (KEX)
583mode (0, default) or in I<key encapsulation method> (KEM) mode (1).
584
585This parameter is optional: if not specified, KEX mode is assumed as the default
586mode for the group.
587
588In KEX mode, in a typical Diffie-Hellman fashion, both sides execute I<keygen>
589then I<derive> against the peer public key. To operate in KEX mode, the group
590implementation must support the provider functions as described in
591L<provider-keyexch(7)>.
592
593In KEM mode, the client executes I<keygen> and sends its public key, the server
594executes I<encapsulate> using the client's public key and sends back the
595resulting I<ciphertext>, finally the client executes I<decapsulate> to retrieve
596the same I<shared secret> generated by the server's I<encapsulate>. To operate
597in KEM mode, the group implementation must support the provider functions as
598described in L<provider-kem(7)>.
599
600Both in KEX and KEM mode, the resulting I<shared secret> is then used according
601to the protocol specification.
602
603=item "tls-min-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_TLS>) <integer>
604
605=item "tls-max-tls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_TLS>) <integer>
606
607=item "tls-min-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MIN_DTLS>) <integer>
608
609=item "tls-max-dtls" (B<OSSL_CAPABILITY_TLS_GROUP_MAX_DTLS>) <integer>
610
611These parameters can be used to describe the minimum and maximum TLS and DTLS
612versions supported by the group. The values equate to the on-the-wire encoding
613of the various TLS versions. For example TLSv1.3 is 0x0304 (772 decimal), and
614TLSv1.2 is 0x0303 (771 decimal). A 0 indicates that there is no defined minimum
615or maximum. A -1 indicates that the group should not be used in that protocol.
616
617=back
618
619=head1 NOTES
620
621The core_obj_create() and core_obj_add_sigid() functions were not thread safe
622in OpenSSL 3.0.
623
624=head1 EXAMPLES
625
626This is an example of a simple provider made available as a
627dynamically loadable module.
628It implements the fictitious algorithm C<FOO> for the fictitious
629operation C<BAR>.
630
631 #include <malloc.h>
632 #include <openssl/core.h>
633 #include <openssl/core_dispatch.h>
634
635 /* Errors used in this provider */
636 #define E_MALLOC       1
637
638 static const OSSL_ITEM reasons[] = {
639     { E_MALLOC, "memory allocation failure" }.
640     { 0, NULL } /* Termination */
641 };
642
643 /*
644  * To ensure we get the function signature right, forward declare
645  * them using function types provided by openssl/core_dispatch.h
646  */
647 OSSL_FUNC_bar_newctx_fn foo_newctx;
648 OSSL_FUNC_bar_freectx_fn foo_freectx;
649 OSSL_FUNC_bar_init_fn foo_init;
650 OSSL_FUNC_bar_update_fn foo_update;
651 OSSL_FUNC_bar_final_fn foo_final;
652
653 OSSL_FUNC_provider_query_operation_fn p_query;
654 OSSL_FUNC_provider_get_reason_strings_fn p_reasons;
655 OSSL_FUNC_provider_teardown_fn p_teardown;
656
657 OSSL_provider_init_fn OSSL_provider_init;
658
659 OSSL_FUNC_core_put_error *c_put_error = NULL;
660
661 /* Provider context */
662 struct prov_ctx_st {
663     OSSL_CORE_HANDLE *handle;
664 }
665
666 /* operation context for the algorithm FOO */
667 struct foo_ctx_st {
668     struct prov_ctx_st *provctx;
669     int b;
670 };
671
672 static void *foo_newctx(void *provctx)
673 {
674     struct foo_ctx_st *fooctx = malloc(sizeof(*fooctx));
675
676     if (fooctx != NULL)
677         fooctx->provctx = provctx;
678     else
679         c_put_error(provctx->handle, E_MALLOC, __FILE__, __LINE__);
680     return fooctx;
681 }
682
683 static void foo_freectx(void *fooctx)
684 {
685     free(fooctx);
686 }
687
688 static int foo_init(void *vfooctx)
689 {
690     struct foo_ctx_st *fooctx = vfooctx;
691
692     fooctx->b = 0x33;
693 }
694
695 static int foo_update(void *vfooctx, unsigned char *in, size_t inl)
696 {
697     struct foo_ctx_st *fooctx = vfooctx;
698
699     /* did you expect something serious? */
700     if (inl == 0)
701         return 1;
702     for (; inl-- > 0; in++)
703         *in ^= fooctx->b;
704     return 1;
705 }
706
707 static int foo_final(void *vfooctx)
708 {
709     struct foo_ctx_st *fooctx = vfooctx;
710
711     fooctx->b = 0x66;
712 }
713
714 static const OSSL_DISPATCH foo_fns[] = {
715     { OSSL_FUNC_BAR_NEWCTX, (void (*)(void))foo_newctx },
716     { OSSL_FUNC_BAR_FREECTX, (void (*)(void))foo_freectx },
717     { OSSL_FUNC_BAR_INIT, (void (*)(void))foo_init },
718     { OSSL_FUNC_BAR_UPDATE, (void (*)(void))foo_update },
719     { OSSL_FUNC_BAR_FINAL, (void (*)(void))foo_final },
720     { 0, NULL }
721 };
722
723 static const OSSL_ALGORITHM bars[] = {
724     { "FOO", "provider=chumbawamba", foo_fns },
725     { NULL, NULL, NULL }
726 };
727
728 static const OSSL_ALGORITHM *p_query(void *provctx, int operation_id,
729                                      int *no_store)
730 {
731     switch (operation_id) {
732     case OSSL_OP_BAR:
733         return bars;
734     }
735     return NULL;
736 }
737
738 static const OSSL_ITEM *p_reasons(void *provctx)
739 {
740     return reasons;
741 }
742
743 static void p_teardown(void *provctx)
744 {
745     free(provctx);
746 }
747
748 static const OSSL_DISPATCH prov_fns[] = {
749     { OSSL_FUNC_PROVIDER_TEARDOWN, (void (*)(void))p_teardown },
750     { OSSL_FUNC_PROVIDER_QUERY_OPERATION, (void (*)(void))p_query },
751     { OSSL_FUNC_PROVIDER_GET_REASON_STRINGS, (void (*)(void))p_reasons },
752     { 0, NULL }
753 };
754
755 int OSSL_provider_init(const OSSL_CORE_HANDLE *handle,
756                        const OSSL_DISPATCH *in,
757                        const OSSL_DISPATCH **out,
758                        void **provctx)
759 {
760     struct prov_ctx_st *pctx = NULL;
761
762     for (; in->function_id != 0; in++)
763         switch (in->function_id) {
764         case OSSL_FUNC_CORE_PUT_ERROR:
765             c_put_error = OSSL_FUNC_core_put_error(in);
766             break;
767         }
768
769     *out = prov_fns;
770
771     if ((pctx = malloc(sizeof(*pctx))) == NULL) {
772         /*
773          * ALEA IACTA EST, if the core retrieves the reason table
774          * regardless, that string will be displayed, otherwise not.
775          */
776         c_put_error(handle, E_MALLOC, __FILE__, __LINE__);
777         return 0;
778     }
779     pctx->handle = handle;
780     return 1;
781 }
782
783This relies on a few things existing in F<openssl/core_dispatch.h>:
784
785 #define OSSL_OP_BAR            4711
786
787 #define OSSL_FUNC_BAR_NEWCTX      1
788 typedef void *(OSSL_FUNC_bar_newctx_fn)(void *provctx);
789 static ossl_inline OSSL_FUNC_bar_newctx(const OSSL_DISPATCH *opf)
790 { return (OSSL_FUNC_bar_newctx_fn *)opf->function; }
791
792 #define OSSL_FUNC_BAR_FREECTX     2
793 typedef void (OSSL_FUNC_bar_freectx_fn)(void *ctx);
794 static ossl_inline OSSL_FUNC_bar_newctx(const OSSL_DISPATCH *opf)
795 { return (OSSL_FUNC_bar_freectx_fn *)opf->function; }
796
797 #define OSSL_FUNC_BAR_INIT        3
798 typedef void *(OSSL_FUNC_bar_init_fn)(void *ctx);
799 static ossl_inline OSSL_FUNC_bar_init(const OSSL_DISPATCH *opf)
800 { return (OSSL_FUNC_bar_init_fn *)opf->function; }
801
802 #define OSSL_FUNC_BAR_UPDATE      4
803 typedef void *(OSSL_FUNC_bar_update_fn)(void *ctx,
804                                       unsigned char *in, size_t inl);
805 static ossl_inline OSSL_FUNC_bar_update(const OSSL_DISPATCH *opf)
806 { return (OSSL_FUNC_bar_update_fn *)opf->function; }
807
808 #define OSSL_FUNC_BAR_FINAL       5
809 typedef void *(OSSL_FUNC_bar_final_fn)(void *ctx);
810 static ossl_inline OSSL_FUNC_bar_final(const OSSL_DISPATCH *opf)
811 { return (OSSL_FUNC_bar_final_fn *)opf->function; }
812
813=head1 SEE ALSO
814
815L<provider(7)>
816
817=head1 HISTORY
818
819The concept of providers and everything surrounding them was
820introduced in OpenSSL 3.0.
821
822=head1 COPYRIGHT
823
824Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
825
826Licensed under the Apache License 2.0 (the "License").  You may not use
827this file except in compliance with the License.  You can obtain a copy
828in the file LICENSE in the source distribution or at
829L<https://www.openssl.org/source/license.html>.
830
831=cut
832