crypto/encode_decode/decoder_pkey.c - third_party/openssl - Git at Google

 /*
  * Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 #include <openssl/core_names.h>
 #include <openssl/core_object.h>
 #include <openssl/provider.h>
 #include <openssl/evp.h>
 #include <openssl/ui.h>
 #include <openssl/decoder.h>
 #include <openssl/safestack.h>
 #include <openssl/trace.h>
 #include "crypto/evp.h"
 #include "crypto/decoder.h"
 #include "encoder_local.h"
 #include "internal/e_os.h"                /* strcasecmp on Windows */

 int OSSL_DECODER_CTX_set_passphrase(OSSL_DECODER_CTX *ctx,
                                     const unsigned char *kstr,
                                     size_t klen)
 {
     return ossl_pw_set_passphrase(&ctx->pwdata, kstr, klen);
 }

 int OSSL_DECODER_CTX_set_passphrase_ui(OSSL_DECODER_CTX *ctx,
                                        const UI_METHOD *ui_method,
                                        void *ui_data)
 {
     return ossl_pw_set_ui_method(&ctx->pwdata, ui_method, ui_data);
 }

 int OSSL_DECODER_CTX_set_pem_password_cb(OSSL_DECODER_CTX *ctx,
                                          pem_password_cb *cb, void *cbarg)
 {
     return ossl_pw_set_pem_password_cb(&ctx->pwdata, cb, cbarg);
 }

 int OSSL_DECODER_CTX_set_passphrase_cb(OSSL_DECODER_CTX *ctx,
                                        OSSL_PASSPHRASE_CALLBACK *cb,
                                        void *cbarg)
 {
     return ossl_pw_set_ossl_passphrase_cb(&ctx->pwdata, cb, cbarg);
 }

 /*
  * Support for OSSL_DECODER_CTX_new_for_pkey:
  * The construct data, and collecting keymgmt information for it
  */

 DEFINE_STACK_OF(EVP_KEYMGMT)

 struct decoder_pkey_data_st {
     OSSL_LIB_CTX *libctx;
     char *propq;
     int selection;

     STACK_OF(EVP_KEYMGMT) *keymgmts;
     char *object_type;           /* recorded object data type, may be NULL */
     void **object;               /* Where the result should end up */
 };

 static int decoder_construct_pkey(OSSL_DECODER_INSTANCE *decoder_inst,
                                   const OSSL_PARAM *params,
                                   void *construct_data)
 {
     struct decoder_pkey_data_st *data = construct_data;
     OSSL_DECODER *decoder = OSSL_DECODER_INSTANCE_get_decoder(decoder_inst);
     void *decoderctx = OSSL_DECODER_INSTANCE_get_decoder_ctx(decoder_inst);
     const OSSL_PROVIDER *decoder_prov = OSSL_DECODER_get0_provider(decoder);
     EVP_KEYMGMT *keymgmt = NULL;
     const OSSL_PROVIDER *keymgmt_prov = NULL;
     int i, end;
     /*
      * |object_ref| points to a provider reference to an object, its exact
      * contents entirely opaque to us, but may be passed to any provider
      * function that expects this (such as OSSL_FUNC_keymgmt_load().
      *
      * This pointer is considered volatile, i.e. whatever it points at
      * is assumed to be freed as soon as this function returns.
      */
     void *object_ref = NULL;
     size_t object_ref_sz = 0;
     const OSSL_PARAM *p;

     p = OSSL_PARAM_locate_const(params, OSSL_OBJECT_PARAM_DATA_TYPE);
     if (p != NULL) {
         char *object_type = NULL;

         if (!OSSL_PARAM_get_utf8_string(p, &object_type, 0))
             return 0;
         OPENSSL_free(data->object_type);
         data->object_type = object_type;
     }

     /*
      * For stuff that should end up in an EVP_PKEY, we only accept an object
      * reference for the moment.  This enforces that the key data itself
      * remains with the provider.
      */
     p = OSSL_PARAM_locate_const(params, OSSL_OBJECT_PARAM_REFERENCE);
     if (p == NULL || p->data_type != OSSL_PARAM_OCTET_STRING)
         return 0;
     object_ref = p->data;
     object_ref_sz = p->data_size;

     /*
      * First, we try to find a keymgmt that comes from the same provider as
      * the decoder that passed the params.
      */
     end = sk_EVP_KEYMGMT_num(data->keymgmts);
     for (i = 0; i < end; i++) {
         keymgmt = sk_EVP_KEYMGMT_value(data->keymgmts, i);
         keymgmt_prov = EVP_KEYMGMT_get0_provider(keymgmt);

         if (keymgmt_prov == decoder_prov
             && evp_keymgmt_has_load(keymgmt)
             && EVP_KEYMGMT_is_a(keymgmt, data->object_type))
             break;
     }
     if (i < end) {
         /* To allow it to be freed further down */
         if (!EVP_KEYMGMT_up_ref(keymgmt))
             return 0;
     } else if ((keymgmt = EVP_KEYMGMT_fetch(data->libctx,
                                             data->object_type,
                                             data->propq)) != NULL) {
         keymgmt_prov = EVP_KEYMGMT_get0_provider(keymgmt);
     }

     if (keymgmt != NULL) {
         EVP_PKEY *pkey = NULL;
         void *keydata = NULL;

         /*
          * If the EVP_KEYMGMT and the OSSL_DECODER are from the
          * same provider, we assume that the KEYMGMT has a key loading
          * function that can handle the provider reference we hold.
          *
          * Otherwise, we export from the decoder and import the
          * result in the keymgmt.
          */
         if (keymgmt_prov == decoder_prov) {
             keydata = evp_keymgmt_load(keymgmt, object_ref, object_ref_sz);
         } else {
             struct evp_keymgmt_util_try_import_data_st import_data;

             import_data.keymgmt = keymgmt;
             import_data.keydata = NULL;
             import_data.selection = data->selection;

             /*
              * No need to check for errors here, the value of
              * |import_data.keydata| is as much an indicator.
              */
             (void)decoder->export_object(decoderctx,
                                          object_ref, object_ref_sz,
                                          &evp_keymgmt_util_try_import,
                                          &import_data);
             keydata = import_data.keydata;
             import_data.keydata = NULL;
         }

         if (keydata != NULL
             && (pkey = evp_keymgmt_util_make_pkey(keymgmt, keydata)) == NULL)
             evp_keymgmt_freedata(keymgmt, keydata);

         *data->object = pkey;

         /*
          * evp_keymgmt_util_make_pkey() increments the reference count when
          * assigning the EVP_PKEY, so we can free the keymgmt here.
          */
         EVP_KEYMGMT_free(keymgmt);
     }
     /*
      * We successfully looked through, |*ctx->object| determines if we
      * actually found something.
      */
     return (*data->object != NULL);
 }

 static void decoder_clean_pkey_construct_arg(void *construct_data)
 {
     struct decoder_pkey_data_st *data = construct_data;

     if (data != NULL) {
         sk_EVP_KEYMGMT_pop_free(data->keymgmts, EVP_KEYMGMT_free);
         OPENSSL_free(data->propq);
         OPENSSL_free(data->object_type);
         OPENSSL_free(data);
     }
 }

 static void collect_name(const char *name, void *arg)
 {
     STACK_OF(OPENSSL_CSTRING) *names = arg;

     sk_OPENSSL_CSTRING_push(names, name);
 }

 static void collect_keymgmt(EVP_KEYMGMT *keymgmt, void *arg)
 {
     STACK_OF(EVP_KEYMGMT) *keymgmts = arg;

     if (!EVP_KEYMGMT_up_ref(keymgmt) /* ref++ */)
         return;
     if (sk_EVP_KEYMGMT_push(keymgmts, keymgmt) <= 0) {
         EVP_KEYMGMT_free(keymgmt);   /* ref-- */
         return;
     }
 }

 struct collect_decoder_data_st {
     STACK_OF(OPENSSL_CSTRING) *names;
     OSSL_DECODER_CTX *ctx;

     int total;
     unsigned int error_occurred:1;
 };

 static void collect_decoder(OSSL_DECODER *decoder, void *arg)
 {
     struct collect_decoder_data_st *data = arg;
     size_t i, end_i;
     const OSSL_PROVIDER *prov = OSSL_DECODER_get0_provider(decoder);
     void *provctx = OSSL_PROVIDER_get0_provider_ctx(prov);

     if (data->error_occurred)
         return;

     if (data->names == NULL) {
         data->error_occurred = 1;
         return;
     }

     /*
      * Either the caller didn't give a selection, or if they did,
      * the decoder must tell us if it supports that selection to
      * be accepted.  If the decoder doesn't have |does_selection|,
      * it's seen as taking anything.
      */
     if (decoder->does_selection != NULL
             && !decoder->does_selection(provctx, data->ctx->selection))
         return;

     OSSL_TRACE_BEGIN(DECODER) {
         BIO_printf(trc_out,
                    "(ctx %p) Checking out decoder %p:\n"
                    "    %s with %s\n",
                    (void *)data->ctx, (void *)decoder,
                    OSSL_DECODER_get0_name(decoder),
                    OSSL_DECODER_get0_properties(decoder));
     } OSSL_TRACE_END(DECODER);

     end_i = sk_OPENSSL_CSTRING_num(data->names);
     for (i = 0; i < end_i; i++) {
         const char *name = sk_OPENSSL_CSTRING_value(data->names, i);

         if (OSSL_DECODER_is_a(decoder, name)) {
             void *decoderctx = NULL;
             OSSL_DECODER_INSTANCE *di = NULL;

             if ((decoderctx = decoder->newctx(provctx)) == NULL) {
                 data->error_occurred = 1;
                 return;
             }
             if ((di = ossl_decoder_instance_new(decoder, decoderctx)) == NULL) {
                 decoder->freectx(decoderctx);
                 data->error_occurred = 1;
                 return;
             }

             OSSL_TRACE_BEGIN(DECODER) {
                 BIO_printf(trc_out,
                            "(ctx %p) Checking out decoder %p:\n"
                            "    %s with %s\n",
                            (void *)data->ctx, (void *)decoder,
                            OSSL_DECODER_get0_name(decoder),
                            OSSL_DECODER_get0_properties(decoder));
             } OSSL_TRACE_END(DECODER);

             if (!ossl_decoder_ctx_add_decoder_inst(data->ctx, di)) {
                 ossl_decoder_instance_free(di);
                 data->error_occurred = 1;
                 return;
             }
             data->total++;

             /* Success */
             return;
         }
     }

     /* Decoder not suitable - but not a fatal error */
     data->error_occurred = 0;
 }

 int ossl_decoder_ctx_setup_for_pkey(OSSL_DECODER_CTX *ctx,
                                     EVP_PKEY **pkey, const char *keytype,
                                     OSSL_LIB_CTX *libctx,
                                     const char *propquery)
 {
     struct decoder_pkey_data_st *process_data = NULL;
     STACK_OF(OPENSSL_CSTRING) *names = NULL;
     const char *input_type = ctx->start_input_type;
     const char *input_structure = ctx->input_structure;
     int ok = 0;
     int isecoid = 0;
     int i, end;

     if (keytype != NULL
             && (strcmp(keytype, "id-ecPublicKey") == 0
                 || strcmp(keytype, "1.2.840.10045.2.1") == 0))
         isecoid = 1;

     OSSL_TRACE_BEGIN(DECODER) {
         BIO_printf(trc_out,
                    "(ctx %p) Looking for decoders producing %s%s%s%s%s%s\n",
                    (void *)ctx,
                    keytype != NULL ? keytype : "",
                    keytype != NULL ? " keys" : "keys of any type",
                    input_type != NULL ? " from " : "",
                    input_type != NULL ? input_type : "",
                    input_structure != NULL ? " with " : "",
                    input_structure != NULL ? input_structure : "");
     } OSSL_TRACE_END(DECODER);

     if ((process_data = OPENSSL_zalloc(sizeof(*process_data))) == NULL
         || (propquery != NULL
             && (process_data->propq = OPENSSL_strdup(propquery)) == NULL)
         || (process_data->keymgmts = sk_EVP_KEYMGMT_new_null()) == NULL
         || (names = sk_OPENSSL_CSTRING_new_null()) == NULL) {
         ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
         goto err;
     }

     process_data->object = (void **)pkey;
     process_data->libctx = libctx;
     process_data->selection = ctx->selection;

     /* First, find all keymgmts to form goals */
     EVP_KEYMGMT_do_all_provided(libctx, collect_keymgmt,
                                 process_data->keymgmts);

     /* Then, we collect all the keymgmt names */
     end = sk_EVP_KEYMGMT_num(process_data->keymgmts);
     for (i = 0; i < end; i++) {
         EVP_KEYMGMT *keymgmt = sk_EVP_KEYMGMT_value(process_data->keymgmts, i);

         /*
          * If the key type is given by the caller, we only use the matching
          * KEYMGMTs, otherwise we use them all.
          * We have to special case SM2 here because of its abuse of the EC OID.
          * The EC OID can be used to identify an EC key or an SM2 key - so if
          * we have seen that OID we try both key types
          */
         if (keytype == NULL
                 || EVP_KEYMGMT_is_a(keymgmt, keytype)
                 || (isecoid && EVP_KEYMGMT_is_a(keymgmt, "SM2"))) {
             if (!EVP_KEYMGMT_names_do_all(keymgmt, collect_name, names)) {
                 ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_INTERNAL_ERROR);
                 goto err;
             }
         }
     }

     OSSL_TRACE_BEGIN(DECODER) {
         end = sk_OPENSSL_CSTRING_num(names);
         BIO_printf(trc_out,
                    "    Found %d keytypes (possibly with duplicates)",
                    end);
         for (i = 0; i < end; i++)
             BIO_printf(trc_out, "%s%s",
                        i == 0 ? ": " : ", ",
                        sk_OPENSSL_CSTRING_value(names, i));
         BIO_printf(trc_out, "\n");
     } OSSL_TRACE_END(DECODER);

     /*
      * Finally, find all decoders that have any keymgmt of the collected
      * keymgmt names
      */
     {
         struct collect_decoder_data_st collect_decoder_data = { NULL, };

         collect_decoder_data.names = names;
         collect_decoder_data.ctx = ctx;
         OSSL_DECODER_do_all_provided(libctx,
                                      collect_decoder, &collect_decoder_data);
         sk_OPENSSL_CSTRING_free(names);
         names = NULL;

         if (collect_decoder_data.error_occurred)
             goto err;

         OSSL_TRACE_BEGIN(DECODER) {
             BIO_printf(trc_out,
                        "(ctx %p) Got %d decoders producing keys\n",
                        (void *)ctx, collect_decoder_data.total);
         } OSSL_TRACE_END(DECODER);
     }

     if (OSSL_DECODER_CTX_get_num_decoders(ctx) != 0) {
         if (!OSSL_DECODER_CTX_set_construct(ctx, decoder_construct_pkey)
             || !OSSL_DECODER_CTX_set_construct_data(ctx, process_data)
             || !OSSL_DECODER_CTX_set_cleanup(ctx,
                                              decoder_clean_pkey_construct_arg))
             goto err;

         process_data = NULL; /* Avoid it being freed */
     }

     ok = 1;
  err:
     decoder_clean_pkey_construct_arg(process_data);
     sk_OPENSSL_CSTRING_free(names);

     return ok;
 }

 OSSL_DECODER_CTX *
 OSSL_DECODER_CTX_new_for_pkey(EVP_PKEY **pkey,
                               const char *input_type,
                               const char *input_structure,
                               const char *keytype, int selection,
                               OSSL_LIB_CTX *libctx, const char *propquery)
 {
     OSSL_DECODER_CTX *ctx = NULL;

     if ((ctx = OSSL_DECODER_CTX_new()) == NULL) {
         ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
         return NULL;
     }

     OSSL_TRACE_BEGIN(DECODER) {
         BIO_printf(trc_out,
                    "(ctx %p) Looking for %s decoders with selection %d\n",
                    (void *)ctx, keytype, selection);
         BIO_printf(trc_out, "    input type: %s, input structure: %s\n",
                    input_type, input_structure);
     } OSSL_TRACE_END(DECODER);

     if (OSSL_DECODER_CTX_set_input_type(ctx, input_type)
         && OSSL_DECODER_CTX_set_input_structure(ctx, input_structure)
         && OSSL_DECODER_CTX_set_selection(ctx, selection)
         && ossl_decoder_ctx_setup_for_pkey(ctx, pkey, keytype,
                                            libctx, propquery)
         && OSSL_DECODER_CTX_add_extra(ctx, libctx, propquery)) {
         OSSL_TRACE_BEGIN(DECODER) {
             BIO_printf(trc_out, "(ctx %p) Got %d decoders\n",
                        (void *)ctx, OSSL_DECODER_CTX_get_num_decoders(ctx));
         } OSSL_TRACE_END(DECODER);
         return ctx;
     }

     OSSL_DECODER_CTX_free(ctx);
     return NULL;
 }
	/*
	* Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the Apache License 2.0 (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	#include <openssl/core_names.h>
	#include <openssl/core_object.h>
	#include <openssl/provider.h>
	#include <openssl/evp.h>
	#include <openssl/ui.h>
	#include <openssl/decoder.h>
	#include <openssl/safestack.h>
	#include <openssl/trace.h>
	#include "crypto/evp.h"
	#include "crypto/decoder.h"
	#include "encoder_local.h"
	#include "internal/e_os.h" /* strcasecmp on Windows */

	int OSSL_DECODER_CTX_set_passphrase(OSSL_DECODER_CTX *ctx,
	const unsigned char *kstr,
	size_t klen)
	{
	return ossl_pw_set_passphrase(&ctx->pwdata, kstr, klen);
	}

	int OSSL_DECODER_CTX_set_passphrase_ui(OSSL_DECODER_CTX *ctx,
	const UI_METHOD *ui_method,
	void *ui_data)
	{
	return ossl_pw_set_ui_method(&ctx->pwdata, ui_method, ui_data);
	}

	int OSSL_DECODER_CTX_set_pem_password_cb(OSSL_DECODER_CTX *ctx,
	pem_password_cb cb, void cbarg)
	{
	return ossl_pw_set_pem_password_cb(&ctx->pwdata, cb, cbarg);
	}

	int OSSL_DECODER_CTX_set_passphrase_cb(OSSL_DECODER_CTX *ctx,
	OSSL_PASSPHRASE_CALLBACK *cb,
	void *cbarg)
	{
	return ossl_pw_set_ossl_passphrase_cb(&ctx->pwdata, cb, cbarg);
	}

	/*
	* Support for OSSL_DECODER_CTX_new_for_pkey:
	* The construct data, and collecting keymgmt information for it
	*/

	DEFINE_STACK_OF(EVP_KEYMGMT)

	struct decoder_pkey_data_st {
	OSSL_LIB_CTX *libctx;
	char *propq;
	int selection;

	STACK_OF(EVP_KEYMGMT) *keymgmts;
	char object_type; / recorded object data type, may be NULL */
	void *object; / Where the result should end up */
	};

	static int decoder_construct_pkey(OSSL_DECODER_INSTANCE *decoder_inst,
	const OSSL_PARAM *params,
	void *construct_data)
	{
	struct decoder_pkey_data_st *data = construct_data;
	OSSL_DECODER *decoder = OSSL_DECODER_INSTANCE_get_decoder(decoder_inst);
	void *decoderctx = OSSL_DECODER_INSTANCE_get_decoder_ctx(decoder_inst);
	const OSSL_PROVIDER *decoder_prov = OSSL_DECODER_get0_provider(decoder);
	EVP_KEYMGMT *keymgmt = NULL;
	const OSSL_PROVIDER *keymgmt_prov = NULL;
	int i, end;
	/*
	* \|object_ref\| points to a provider reference to an object, its exact
	* contents entirely opaque to us, but may be passed to any provider
	* function that expects this (such as OSSL_FUNC_keymgmt_load().
	*
	* This pointer is considered volatile, i.e. whatever it points at
	* is assumed to be freed as soon as this function returns.
	*/
	void *object_ref = NULL;
	size_t object_ref_sz = 0;
	const OSSL_PARAM *p;

	p = OSSL_PARAM_locate_const(params, OSSL_OBJECT_PARAM_DATA_TYPE);
	if (p != NULL) {
	char *object_type = NULL;

	if (!OSSL_PARAM_get_utf8_string(p, &object_type, 0))
	return 0;
	OPENSSL_free(data->object_type);
	data->object_type = object_type;
	}

	/*
	* For stuff that should end up in an EVP_PKEY, we only accept an object
	* reference for the moment. This enforces that the key data itself
	* remains with the provider.
	*/
	p = OSSL_PARAM_locate_const(params, OSSL_OBJECT_PARAM_REFERENCE);
	if (p == NULL \|\| p->data_type != OSSL_PARAM_OCTET_STRING)
	return 0;
	object_ref = p->data;
	object_ref_sz = p->data_size;

	/*
	* First, we try to find a keymgmt that comes from the same provider as
	* the decoder that passed the params.
	*/
	end = sk_EVP_KEYMGMT_num(data->keymgmts);
	for (i = 0; i < end; i++) {
	keymgmt = sk_EVP_KEYMGMT_value(data->keymgmts, i);
	keymgmt_prov = EVP_KEYMGMT_get0_provider(keymgmt);

	if (keymgmt_prov == decoder_prov
	&& evp_keymgmt_has_load(keymgmt)
	&& EVP_KEYMGMT_is_a(keymgmt, data->object_type))
	break;
	}
	if (i < end) {
	/* To allow it to be freed further down */
	if (!EVP_KEYMGMT_up_ref(keymgmt))
	return 0;
	} else if ((keymgmt = EVP_KEYMGMT_fetch(data->libctx,
	data->object_type,
	data->propq)) != NULL) {
	keymgmt_prov = EVP_KEYMGMT_get0_provider(keymgmt);
	}

	if (keymgmt != NULL) {
	EVP_PKEY *pkey = NULL;
	void *keydata = NULL;

	/*
	* If the EVP_KEYMGMT and the OSSL_DECODER are from the
	* same provider, we assume that the KEYMGMT has a key loading
	* function that can handle the provider reference we hold.
	*
	* Otherwise, we export from the decoder and import the
	* result in the keymgmt.
	*/
	if (keymgmt_prov == decoder_prov) {
	keydata = evp_keymgmt_load(keymgmt, object_ref, object_ref_sz);
	} else {
	struct evp_keymgmt_util_try_import_data_st import_data;

	import_data.keymgmt = keymgmt;
	import_data.keydata = NULL;
	import_data.selection = data->selection;

	/*
	* No need to check for errors here, the value of
	* \|import_data.keydata\| is as much an indicator.
	*/
	(void)decoder->export_object(decoderctx,
	object_ref, object_ref_sz,
	&evp_keymgmt_util_try_import,
	&import_data);
	keydata = import_data.keydata;
	import_data.keydata = NULL;
	}

	if (keydata != NULL
	&& (pkey = evp_keymgmt_util_make_pkey(keymgmt, keydata)) == NULL)
	evp_keymgmt_freedata(keymgmt, keydata);

	*data->object = pkey;

	/*
	* evp_keymgmt_util_make_pkey() increments the reference count when
	* assigning the EVP_PKEY, so we can free the keymgmt here.
	*/
	EVP_KEYMGMT_free(keymgmt);
	}
	/*
	* We successfully looked through, \|*ctx->object\| determines if we
	* actually found something.
	*/
	return (*data->object != NULL);
	}

	static void decoder_clean_pkey_construct_arg(void *construct_data)
	{
	struct decoder_pkey_data_st *data = construct_data;

	if (data != NULL) {
	sk_EVP_KEYMGMT_pop_free(data->keymgmts, EVP_KEYMGMT_free);
	OPENSSL_free(data->propq);
	OPENSSL_free(data->object_type);
	OPENSSL_free(data);
	}
	}

	static void collect_name(const char name, void arg)
	{
	STACK_OF(OPENSSL_CSTRING) *names = arg;

	sk_OPENSSL_CSTRING_push(names, name);
	}

	static void collect_keymgmt(EVP_KEYMGMT keymgmt, void arg)
	{
	STACK_OF(EVP_KEYMGMT) *keymgmts = arg;

	if (!EVP_KEYMGMT_up_ref(keymgmt) /* ref++ */)
	return;
	if (sk_EVP_KEYMGMT_push(keymgmts, keymgmt) <= 0) {
	EVP_KEYMGMT_free(keymgmt); /* ref-- */
	return;
	}
	}

	struct collect_decoder_data_st {
	STACK_OF(OPENSSL_CSTRING) *names;
	OSSL_DECODER_CTX *ctx;

	int total;
	unsigned int error_occurred:1;
	};

	static void collect_decoder(OSSL_DECODER decoder, void arg)
	{
	struct collect_decoder_data_st *data = arg;
	size_t i, end_i;
	const OSSL_PROVIDER *prov = OSSL_DECODER_get0_provider(decoder);
	void *provctx = OSSL_PROVIDER_get0_provider_ctx(prov);

	if (data->error_occurred)
	return;

	if (data->names == NULL) {
	data->error_occurred = 1;
	return;
	}

	/*
	* Either the caller didn't give a selection, or if they did,
	* the decoder must tell us if it supports that selection to
	* be accepted. If the decoder doesn't have \|does_selection\|,
	* it's seen as taking anything.
	*/
	if (decoder->does_selection != NULL
	&& !decoder->does_selection(provctx, data->ctx->selection))
	return;

	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out,
	"(ctx %p) Checking out decoder %p:\n"
	" %s with %s\n",
	(void )data->ctx, (void )decoder,
	OSSL_DECODER_get0_name(decoder),
	OSSL_DECODER_get0_properties(decoder));
	} OSSL_TRACE_END(DECODER);

	end_i = sk_OPENSSL_CSTRING_num(data->names);
	for (i = 0; i < end_i; i++) {
	const char *name = sk_OPENSSL_CSTRING_value(data->names, i);

	if (OSSL_DECODER_is_a(decoder, name)) {
	void *decoderctx = NULL;
	OSSL_DECODER_INSTANCE *di = NULL;

	if ((decoderctx = decoder->newctx(provctx)) == NULL) {
	data->error_occurred = 1;
	return;
	}
	if ((di = ossl_decoder_instance_new(decoder, decoderctx)) == NULL) {
	decoder->freectx(decoderctx);
	data->error_occurred = 1;
	return;
	}

	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out,
	"(ctx %p) Checking out decoder %p:\n"
	" %s with %s\n",
	(void )data->ctx, (void )decoder,
	OSSL_DECODER_get0_name(decoder),
	OSSL_DECODER_get0_properties(decoder));
	} OSSL_TRACE_END(DECODER);

	if (!ossl_decoder_ctx_add_decoder_inst(data->ctx, di)) {
	ossl_decoder_instance_free(di);
	data->error_occurred = 1;
	return;
	}
	data->total++;

	/* Success */
	return;
	}
	}

	/* Decoder not suitable - but not a fatal error */
	data->error_occurred = 0;
	}

	int ossl_decoder_ctx_setup_for_pkey(OSSL_DECODER_CTX *ctx,
	EVP_PKEY *pkey, const char keytype,
	OSSL_LIB_CTX *libctx,
	const char *propquery)
	{
	struct decoder_pkey_data_st *process_data = NULL;
	STACK_OF(OPENSSL_CSTRING) *names = NULL;
	const char *input_type = ctx->start_input_type;
	const char *input_structure = ctx->input_structure;
	int ok = 0;
	int isecoid = 0;
	int i, end;

	if (keytype != NULL
	&& (strcmp(keytype, "id-ecPublicKey") == 0
	\|\| strcmp(keytype, "1.2.840.10045.2.1") == 0))
	isecoid = 1;

	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out,
	"(ctx %p) Looking for decoders producing %s%s%s%s%s%s\n",
	(void *)ctx,
	keytype != NULL ? keytype : "",
	keytype != NULL ? " keys" : "keys of any type",
	input_type != NULL ? " from " : "",
	input_type != NULL ? input_type : "",
	input_structure != NULL ? " with " : "",
	input_structure != NULL ? input_structure : "");
	} OSSL_TRACE_END(DECODER);

	if ((process_data = OPENSSL_zalloc(sizeof(*process_data))) == NULL
	\|\| (propquery != NULL
	&& (process_data->propq = OPENSSL_strdup(propquery)) == NULL)
	\|\| (process_data->keymgmts = sk_EVP_KEYMGMT_new_null()) == NULL
	\|\| (names = sk_OPENSSL_CSTRING_new_null()) == NULL) {
	ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
	goto err;
	}

	process_data->object = (void **)pkey;
	process_data->libctx = libctx;
	process_data->selection = ctx->selection;

	/* First, find all keymgmts to form goals */
	EVP_KEYMGMT_do_all_provided(libctx, collect_keymgmt,
	process_data->keymgmts);

	/* Then, we collect all the keymgmt names */
	end = sk_EVP_KEYMGMT_num(process_data->keymgmts);
	for (i = 0; i < end; i++) {
	EVP_KEYMGMT *keymgmt = sk_EVP_KEYMGMT_value(process_data->keymgmts, i);

	/*
	* If the key type is given by the caller, we only use the matching
	* KEYMGMTs, otherwise we use them all.
	* We have to special case SM2 here because of its abuse of the EC OID.
	* The EC OID can be used to identify an EC key or an SM2 key - so if
	* we have seen that OID we try both key types
	*/
	if (keytype == NULL
	\|\| EVP_KEYMGMT_is_a(keymgmt, keytype)
	\|\| (isecoid && EVP_KEYMGMT_is_a(keymgmt, "SM2"))) {
	if (!EVP_KEYMGMT_names_do_all(keymgmt, collect_name, names)) {
	ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_INTERNAL_ERROR);
	goto err;
	}
	}
	}

	OSSL_TRACE_BEGIN(DECODER) {
	end = sk_OPENSSL_CSTRING_num(names);
	BIO_printf(trc_out,
	" Found %d keytypes (possibly with duplicates)",
	end);
	for (i = 0; i < end; i++)
	BIO_printf(trc_out, "%s%s",
	i == 0 ? ": " : ", ",
	sk_OPENSSL_CSTRING_value(names, i));
	BIO_printf(trc_out, "\n");
	} OSSL_TRACE_END(DECODER);

	/*
	* Finally, find all decoders that have any keymgmt of the collected
	* keymgmt names
	*/
	{
	struct collect_decoder_data_st collect_decoder_data = { NULL, };

	collect_decoder_data.names = names;
	collect_decoder_data.ctx = ctx;
	OSSL_DECODER_do_all_provided(libctx,
	collect_decoder, &collect_decoder_data);
	sk_OPENSSL_CSTRING_free(names);
	names = NULL;

	if (collect_decoder_data.error_occurred)
	goto err;

	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out,
	"(ctx %p) Got %d decoders producing keys\n",
	(void *)ctx, collect_decoder_data.total);
	} OSSL_TRACE_END(DECODER);
	}

	if (OSSL_DECODER_CTX_get_num_decoders(ctx) != 0) {
	if (!OSSL_DECODER_CTX_set_construct(ctx, decoder_construct_pkey)
	\|\| !OSSL_DECODER_CTX_set_construct_data(ctx, process_data)
	\|\| !OSSL_DECODER_CTX_set_cleanup(ctx,
	decoder_clean_pkey_construct_arg))
	goto err;

	process_data = NULL; /* Avoid it being freed */
	}

	ok = 1;
	err:
	decoder_clean_pkey_construct_arg(process_data);
	sk_OPENSSL_CSTRING_free(names);

	return ok;
	}

	OSSL_DECODER_CTX *
	OSSL_DECODER_CTX_new_for_pkey(EVP_PKEY **pkey,
	const char *input_type,
	const char *input_structure,
	const char *keytype, int selection,
	OSSL_LIB_CTX libctx, const char propquery)
	{
	OSSL_DECODER_CTX *ctx = NULL;

	if ((ctx = OSSL_DECODER_CTX_new()) == NULL) {
	ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
	return NULL;
	}

	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out,
	"(ctx %p) Looking for %s decoders with selection %d\n",
	(void *)ctx, keytype, selection);
	BIO_printf(trc_out, " input type: %s, input structure: %s\n",
	input_type, input_structure);
	} OSSL_TRACE_END(DECODER);

	if (OSSL_DECODER_CTX_set_input_type(ctx, input_type)
	&& OSSL_DECODER_CTX_set_input_structure(ctx, input_structure)
	&& OSSL_DECODER_CTX_set_selection(ctx, selection)
	&& ossl_decoder_ctx_setup_for_pkey(ctx, pkey, keytype,
	libctx, propquery)
	&& OSSL_DECODER_CTX_add_extra(ctx, libctx, propquery)) {
	OSSL_TRACE_BEGIN(DECODER) {
	BIO_printf(trc_out, "(ctx %p) Got %d decoders\n",
	(void *)ctx, OSSL_DECODER_CTX_get_num_decoders(ctx));
	} OSSL_TRACE_END(DECODER);
	return ctx;
	}

	OSSL_DECODER_CTX_free(ctx);
	return NULL;
	}