crypto/initthread.c - third_party/openssl - Git at Google

 /*
  * Copyright 2019-2022 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/crypto.h>
 #include <openssl/core_dispatch.h>
 #include "crypto/cryptlib.h"
 #include "prov/providercommon.h"
 #include "internal/thread_once.h"
 #include "crypto/context.h"

 #ifdef FIPS_MODULE
 #include "prov/provider_ctx.h"

 /*
  * Thread aware code may want to be told about thread stop events. We register
  * to hear about those thread stop events when we see a new thread has started.
  * We call the ossl_init_thread_start function to do that. In the FIPS provider
  * we have our own copy of ossl_init_thread_start, which cascades notifications
  * about threads stopping from libcrypto to all the code in the FIPS provider
  * that needs to know about it.
  *
  * The FIPS provider tells libcrypto about which threads it is interested in
  * by calling "c_thread_start" which is a function pointer created during
  * provider initialisation (i.e. OSSL_init_provider).
  */
 extern OSSL_FUNC_core_thread_start_fn *c_thread_start;
 #endif

 typedef struct thread_event_handler_st THREAD_EVENT_HANDLER;
 struct thread_event_handler_st {
 #ifndef FIPS_MODULE
     const void *index;
 #endif
     void *arg;
     OSSL_thread_stop_handler_fn handfn;
     THREAD_EVENT_HANDLER *next;
 };

 #ifndef FIPS_MODULE
 DEFINE_SPECIAL_STACK_OF(THREAD_EVENT_HANDLER_PTR, THREAD_EVENT_HANDLER *)

 typedef struct global_tevent_register_st GLOBAL_TEVENT_REGISTER;
 struct global_tevent_register_st {
     STACK_OF(THREAD_EVENT_HANDLER_PTR) *skhands;
     CRYPTO_RWLOCK *lock;
 };

 static GLOBAL_TEVENT_REGISTER *glob_tevent_reg = NULL;

 static CRYPTO_ONCE tevent_register_runonce = CRYPTO_ONCE_STATIC_INIT;

 DEFINE_RUN_ONCE_STATIC(create_global_tevent_register)
 {
     glob_tevent_reg = OPENSSL_zalloc(sizeof(*glob_tevent_reg));
     if (glob_tevent_reg == NULL)
         return 0;

     glob_tevent_reg->skhands = sk_THREAD_EVENT_HANDLER_PTR_new_null();
     glob_tevent_reg->lock = CRYPTO_THREAD_lock_new();
     if (glob_tevent_reg->skhands == NULL || glob_tevent_reg->lock == NULL) {
         sk_THREAD_EVENT_HANDLER_PTR_free(glob_tevent_reg->skhands);
         CRYPTO_THREAD_lock_free(glob_tevent_reg->lock);
         OPENSSL_free(glob_tevent_reg);
         glob_tevent_reg = NULL;
         return 0;
     }

     return 1;
 }

 static GLOBAL_TEVENT_REGISTER *get_global_tevent_register(void)
 {
     if (!RUN_ONCE(&tevent_register_runonce, create_global_tevent_register))
         return NULL;
     return glob_tevent_reg;
 }
 #endif

 #ifndef FIPS_MODULE
 static int  init_thread_push_handlers(THREAD_EVENT_HANDLER **hands);
 static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin);
 static void init_thread_destructor(void *hands);
 static int  init_thread_deregister(void *arg, int all);
 #endif
 static void init_thread_stop(void *arg, THREAD_EVENT_HANDLER **hands);

 static THREAD_EVENT_HANDLER **
 init_get_thread_local(CRYPTO_THREAD_LOCAL *local, int alloc, int keep)
 {
     THREAD_EVENT_HANDLER **hands = CRYPTO_THREAD_get_local(local);

     if (alloc) {
         if (hands == NULL) {

             if ((hands = OPENSSL_zalloc(sizeof(*hands))) == NULL)
                 return NULL;

             if (!CRYPTO_THREAD_set_local(local, hands)) {
                 OPENSSL_free(hands);
                 return NULL;
             }

 #ifndef FIPS_MODULE
             if (!init_thread_push_handlers(hands)) {
                 CRYPTO_THREAD_set_local(local, NULL);
                 OPENSSL_free(hands);
                 return NULL;
             }
 #endif
         }
     } else if (!keep) {
         CRYPTO_THREAD_set_local(local, NULL);
     }

     return hands;
 }

 #ifndef FIPS_MODULE
 /*
  * Since per-thread-specific-data destructors are not universally
  * available, i.e. not on Windows, only below CRYPTO_THREAD_LOCAL key
  * is assumed to have destructor associated. And then an effort is made
  * to call this single destructor on non-pthread platform[s].
  *
  * Initial value is "impossible". It is used as guard value to shortcut
  * destructor for threads terminating before libcrypto is initialized or
  * after it's de-initialized. Access to the key doesn't have to be
  * serialized for the said threads, because they didn't use libcrypto
  * and it doesn't matter if they pick "impossible" or dereference real
  * key value and pull NULL past initialization in the first thread that
  * intends to use libcrypto.
  */
 static union {
     long sane;
     CRYPTO_THREAD_LOCAL value;
 } destructor_key = { -1 };

 /*
  * The thread event handler list is a thread specific linked list
  * of callback functions which are invoked in list order by the
  * current thread in case of certain events. (Currently, there is
  * only one type of event, the 'thread stop' event.)
  *
  * We also keep a global reference to that linked list, so that we
  * can deregister handlers if necessary before all the threads are
  * stopped.
  */
 static int init_thread_push_handlers(THREAD_EVENT_HANDLER **hands)
 {
     int ret;
     GLOBAL_TEVENT_REGISTER *gtr;

     gtr = get_global_tevent_register();
     if (gtr == NULL)
         return 0;

     if (!CRYPTO_THREAD_write_lock(gtr->lock))
         return 0;
     ret = (sk_THREAD_EVENT_HANDLER_PTR_push(gtr->skhands, hands) != 0);
     CRYPTO_THREAD_unlock(gtr->lock);

     return ret;
 }

 static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin)
 {
     GLOBAL_TEVENT_REGISTER *gtr;
     int i;

     gtr = get_global_tevent_register();
     if (gtr == NULL)
         return;
     if (!CRYPTO_THREAD_write_lock(gtr->lock))
         return;
     for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
         THREAD_EVENT_HANDLER **hands
             = sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);

         if (hands == handsin) {
             sk_THREAD_EVENT_HANDLER_PTR_delete(gtr->skhands, i);
             CRYPTO_THREAD_unlock(gtr->lock);
             return;
         }
     }
     CRYPTO_THREAD_unlock(gtr->lock);
     return;
 }

 static void init_thread_destructor(void *hands)
 {
     init_thread_stop(NULL, (THREAD_EVENT_HANDLER **)hands);
     init_thread_remove_handlers(hands);
     OPENSSL_free(hands);
 }

 int ossl_init_thread(void)
 {
     if (!CRYPTO_THREAD_init_local(&destructor_key.value,
                                   init_thread_destructor))
         return 0;

     return 1;
 }

 void ossl_cleanup_thread(void)
 {
     init_thread_deregister(NULL, 1);
     CRYPTO_THREAD_cleanup_local(&destructor_key.value);
     destructor_key.sane = -1;
 }

 void OPENSSL_thread_stop_ex(OSSL_LIB_CTX *ctx)
 {
     ctx = ossl_lib_ctx_get_concrete(ctx);
     /*
      * It would be nice if we could figure out a way to do this on all threads
      * that have used the OSSL_LIB_CTX when the context is freed. This is
      * currently not possible due to the use of thread local variables.
      */
     ossl_ctx_thread_stop(ctx);
 }

 void OPENSSL_thread_stop(void)
 {
     if (destructor_key.sane != -1) {
         THREAD_EVENT_HANDLER **hands
             = init_get_thread_local(&destructor_key.value, 0, 0);
         init_thread_stop(NULL, hands);

         init_thread_remove_handlers(hands);
         OPENSSL_free(hands);
     }
 }

 void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
 {
     if (destructor_key.sane != -1) {
         THREAD_EVENT_HANDLER **hands
             = init_get_thread_local(&destructor_key.value, 0, 1);
         init_thread_stop(ctx, hands);
     }
 }

 #else

 void *ossl_thread_event_ctx_new(OSSL_LIB_CTX *libctx)
 {
     THREAD_EVENT_HANDLER **hands = NULL;
     CRYPTO_THREAD_LOCAL *tlocal = OPENSSL_zalloc(sizeof(*tlocal));

     if (tlocal == NULL)
         return NULL;

     if (!CRYPTO_THREAD_init_local(tlocal,  NULL)) {
         goto err;
     }

     hands = OPENSSL_zalloc(sizeof(*hands));
     if (hands == NULL)
         goto err;

     if (!CRYPTO_THREAD_set_local(tlocal, hands))
         goto err;

     return tlocal;
  err:
     OPENSSL_free(hands);
     OPENSSL_free(tlocal);
     return NULL;
 }

 void ossl_thread_event_ctx_free(void *tlocal)
 {
     OPENSSL_free(tlocal);
 }

 static void ossl_arg_thread_stop(void *arg)
 {
     ossl_ctx_thread_stop((OSSL_LIB_CTX *)arg);
 }

 void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
 {
     THREAD_EVENT_HANDLER **hands;
     CRYPTO_THREAD_LOCAL *local
         = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);

     if (local == NULL)
         return;
     hands = init_get_thread_local(local, 0, 0);
     init_thread_stop(ctx, hands);
     OPENSSL_free(hands);
 }
 #endif /* FIPS_MODULE */


 static void init_thread_stop(void *arg, THREAD_EVENT_HANDLER **hands)
 {
     THREAD_EVENT_HANDLER *curr, *prev = NULL, *tmp;
 #ifndef FIPS_MODULE
     GLOBAL_TEVENT_REGISTER *gtr;
 #endif

     /* Can't do much about this */
     if (hands == NULL)
         return;

 #ifndef FIPS_MODULE
     gtr = get_global_tevent_register();
     if (gtr == NULL)
         return;

     if (!CRYPTO_THREAD_write_lock(gtr->lock))
         return;
 #endif

     curr = *hands;
     while (curr != NULL) {
         if (arg != NULL && curr->arg != arg) {
             prev = curr;
             curr = curr->next;
             continue;
         }
         curr->handfn(curr->arg);
         if (prev == NULL)
             *hands = curr->next;
         else
             prev->next = curr->next;

         tmp = curr;
         curr = curr->next;

         OPENSSL_free(tmp);
     }
 #ifndef FIPS_MODULE
     CRYPTO_THREAD_unlock(gtr->lock);
 #endif
 }

 int ossl_init_thread_start(const void *index, void *arg,
                            OSSL_thread_stop_handler_fn handfn)
 {
     THREAD_EVENT_HANDLER **hands;
     THREAD_EVENT_HANDLER *hand;
 #ifdef FIPS_MODULE
     OSSL_LIB_CTX *ctx = arg;

     /*
      * In FIPS mode the list of THREAD_EVENT_HANDLERs is unique per combination
      * of OSSL_LIB_CTX and thread. This is because in FIPS mode each
      * OSSL_LIB_CTX gets informed about thread stop events individually.
      */
     CRYPTO_THREAD_LOCAL *local
         = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);
 #else
     /*
      * Outside of FIPS mode the list of THREAD_EVENT_HANDLERs is unique per
      * thread, but may hold multiple OSSL_LIB_CTXs. We only get told about
      * thread stop events globally, so we have to ensure all affected
      * OSSL_LIB_CTXs are informed.
      */
     CRYPTO_THREAD_LOCAL *local = &destructor_key.value;
 #endif

     hands = init_get_thread_local(local, 1, 0);
     if (hands == NULL)
         return 0;

 #ifdef FIPS_MODULE
     if (*hands == NULL) {
         /*
          * We've not yet registered any handlers for this thread. We need to get
          * libcrypto to tell us about later thread stop events. c_thread_start
          * is a callback to libcrypto defined in fipsprov.c
          */
         if (!c_thread_start(FIPS_get_core_handle(ctx), ossl_arg_thread_stop,
                             ctx))
             return 0;
     }
 #endif

     hand = OPENSSL_malloc(sizeof(*hand));
     if (hand == NULL)
         return 0;

     hand->handfn = handfn;
     hand->arg = arg;
 #ifndef FIPS_MODULE
     hand->index = index;
 #endif
     hand->next = *hands;
     *hands = hand;

     return 1;
 }

 #ifndef FIPS_MODULE
 static int init_thread_deregister(void *index, int all)
 {
     GLOBAL_TEVENT_REGISTER *gtr;
     int i;

     gtr = get_global_tevent_register();
     if (gtr == NULL)
         return 0;
     if (!all) {
         if (!CRYPTO_THREAD_write_lock(gtr->lock))
             return 0;
     } else {
         glob_tevent_reg = NULL;
     }
     for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
         THREAD_EVENT_HANDLER **hands
             = sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);
         THREAD_EVENT_HANDLER *curr = NULL, *prev = NULL, *tmp;

         if (hands == NULL) {
             if (!all)
                 CRYPTO_THREAD_unlock(gtr->lock);
             return 0;
         }
         curr = *hands;
         while (curr != NULL) {
             if (all || curr->index == index) {
                 if (prev != NULL)
                     prev->next = curr->next;
                 else
                     *hands = curr->next;
                 tmp = curr;
                 curr = curr->next;
                 OPENSSL_free(tmp);
                 continue;
             }
             prev = curr;
             curr = curr->next;
         }
         if (all)
             OPENSSL_free(hands);
     }
     if (all) {
         CRYPTO_THREAD_lock_free(gtr->lock);
         sk_THREAD_EVENT_HANDLER_PTR_free(gtr->skhands);
         OPENSSL_free(gtr);
     } else {
         CRYPTO_THREAD_unlock(gtr->lock);
     }
     return 1;
 }

 int ossl_init_thread_deregister(void *index)
 {
     return init_thread_deregister(index, 0);
 }
 #endif
	/*
	* Copyright 2019-2022 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/crypto.h>
	#include <openssl/core_dispatch.h>
	#include "crypto/cryptlib.h"
	#include "prov/providercommon.h"
	#include "internal/thread_once.h"
	#include "crypto/context.h"

	#ifdef FIPS_MODULE
	#include "prov/provider_ctx.h"

	/*
	* Thread aware code may want to be told about thread stop events. We register
	* to hear about those thread stop events when we see a new thread has started.
	* We call the ossl_init_thread_start function to do that. In the FIPS provider
	* we have our own copy of ossl_init_thread_start, which cascades notifications
	* about threads stopping from libcrypto to all the code in the FIPS provider
	* that needs to know about it.
	*
	* The FIPS provider tells libcrypto about which threads it is interested in
	* by calling "c_thread_start" which is a function pointer created during
	* provider initialisation (i.e. OSSL_init_provider).
	*/
	extern OSSL_FUNC_core_thread_start_fn *c_thread_start;
	#endif

	typedef struct thread_event_handler_st THREAD_EVENT_HANDLER;
	struct thread_event_handler_st {
	#ifndef FIPS_MODULE
	const void *index;
	#endif
	void *arg;
	OSSL_thread_stop_handler_fn handfn;
	THREAD_EVENT_HANDLER *next;
	};

	#ifndef FIPS_MODULE
	DEFINE_SPECIAL_STACK_OF(THREAD_EVENT_HANDLER_PTR, THREAD_EVENT_HANDLER *)

	typedef struct global_tevent_register_st GLOBAL_TEVENT_REGISTER;
	struct global_tevent_register_st {
	STACK_OF(THREAD_EVENT_HANDLER_PTR) *skhands;
	CRYPTO_RWLOCK *lock;
	};

	static GLOBAL_TEVENT_REGISTER *glob_tevent_reg = NULL;

	static CRYPTO_ONCE tevent_register_runonce = CRYPTO_ONCE_STATIC_INIT;

	DEFINE_RUN_ONCE_STATIC(create_global_tevent_register)
	{
	glob_tevent_reg = OPENSSL_zalloc(sizeof(*glob_tevent_reg));
	if (glob_tevent_reg == NULL)
	return 0;

	glob_tevent_reg->skhands = sk_THREAD_EVENT_HANDLER_PTR_new_null();
	glob_tevent_reg->lock = CRYPTO_THREAD_lock_new();
	if (glob_tevent_reg->skhands == NULL \|\| glob_tevent_reg->lock == NULL) {
	sk_THREAD_EVENT_HANDLER_PTR_free(glob_tevent_reg->skhands);
	CRYPTO_THREAD_lock_free(glob_tevent_reg->lock);
	OPENSSL_free(glob_tevent_reg);
	glob_tevent_reg = NULL;
	return 0;
	}

	return 1;
	}

	static GLOBAL_TEVENT_REGISTER *get_global_tevent_register(void)
	{
	if (!RUN_ONCE(&tevent_register_runonce, create_global_tevent_register))
	return NULL;
	return glob_tevent_reg;
	}
	#endif

	#ifndef FIPS_MODULE
	static int init_thread_push_handlers(THREAD_EVENT_HANDLER **hands);
	static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin);
	static void init_thread_destructor(void *hands);
	static int init_thread_deregister(void *arg, int all);
	#endif
	static void init_thread_stop(void arg, THREAD_EVENT_HANDLER *hands);

	static THREAD_EVENT_HANDLER **
	init_get_thread_local(CRYPTO_THREAD_LOCAL *local, int alloc, int keep)
	{
	THREAD_EVENT_HANDLER **hands = CRYPTO_THREAD_get_local(local);

	if (alloc) {
	if (hands == NULL) {

	if ((hands = OPENSSL_zalloc(sizeof(*hands))) == NULL)
	return NULL;

	if (!CRYPTO_THREAD_set_local(local, hands)) {
	OPENSSL_free(hands);
	return NULL;
	}

	#ifndef FIPS_MODULE
	if (!init_thread_push_handlers(hands)) {
	CRYPTO_THREAD_set_local(local, NULL);
	OPENSSL_free(hands);
	return NULL;
	}
	#endif
	}
	} else if (!keep) {
	CRYPTO_THREAD_set_local(local, NULL);
	}

	return hands;
	}

	#ifndef FIPS_MODULE
	/*
	* Since per-thread-specific-data destructors are not universally
	* available, i.e. not on Windows, only below CRYPTO_THREAD_LOCAL key
	* is assumed to have destructor associated. And then an effort is made
	* to call this single destructor on non-pthread platform[s].
	*
	* Initial value is "impossible". It is used as guard value to shortcut
	* destructor for threads terminating before libcrypto is initialized or
	* after it's de-initialized. Access to the key doesn't have to be
	* serialized for the said threads, because they didn't use libcrypto
	* and it doesn't matter if they pick "impossible" or dereference real
	* key value and pull NULL past initialization in the first thread that
	* intends to use libcrypto.
	*/
	static union {
	long sane;
	CRYPTO_THREAD_LOCAL value;
	} destructor_key = { -1 };

	/*
	* The thread event handler list is a thread specific linked list
	* of callback functions which are invoked in list order by the
	* current thread in case of certain events. (Currently, there is
	* only one type of event, the 'thread stop' event.)
	*
	* We also keep a global reference to that linked list, so that we
	* can deregister handlers if necessary before all the threads are
	* stopped.
	*/
	static int init_thread_push_handlers(THREAD_EVENT_HANDLER **hands)
	{
	int ret;
	GLOBAL_TEVENT_REGISTER *gtr;

	gtr = get_global_tevent_register();
	if (gtr == NULL)
	return 0;

	if (!CRYPTO_THREAD_write_lock(gtr->lock))
	return 0;
	ret = (sk_THREAD_EVENT_HANDLER_PTR_push(gtr->skhands, hands) != 0);
	CRYPTO_THREAD_unlock(gtr->lock);

	return ret;
	}

	static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin)
	{
	GLOBAL_TEVENT_REGISTER *gtr;
	int i;

	gtr = get_global_tevent_register();
	if (gtr == NULL)
	return;
	if (!CRYPTO_THREAD_write_lock(gtr->lock))
	return;
	for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
	THREAD_EVENT_HANDLER **hands
	= sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);

	if (hands == handsin) {
	sk_THREAD_EVENT_HANDLER_PTR_delete(gtr->skhands, i);
	CRYPTO_THREAD_unlock(gtr->lock);
	return;
	}
	}
	CRYPTO_THREAD_unlock(gtr->lock);
	return;
	}

	static void init_thread_destructor(void *hands)
	{
	init_thread_stop(NULL, (THREAD_EVENT_HANDLER **)hands);
	init_thread_remove_handlers(hands);
	OPENSSL_free(hands);
	}

	int ossl_init_thread(void)
	{
	if (!CRYPTO_THREAD_init_local(&destructor_key.value,
	init_thread_destructor))
	return 0;

	return 1;
	}

	void ossl_cleanup_thread(void)
	{
	init_thread_deregister(NULL, 1);
	CRYPTO_THREAD_cleanup_local(&destructor_key.value);
	destructor_key.sane = -1;
	}

	void OPENSSL_thread_stop_ex(OSSL_LIB_CTX *ctx)
	{
	ctx = ossl_lib_ctx_get_concrete(ctx);
	/*
	* It would be nice if we could figure out a way to do this on all threads
	* that have used the OSSL_LIB_CTX when the context is freed. This is
	* currently not possible due to the use of thread local variables.
	*/
	ossl_ctx_thread_stop(ctx);
	}

	void OPENSSL_thread_stop(void)
	{
	if (destructor_key.sane != -1) {
	THREAD_EVENT_HANDLER **hands
	= init_get_thread_local(&destructor_key.value, 0, 0);
	init_thread_stop(NULL, hands);

	init_thread_remove_handlers(hands);
	OPENSSL_free(hands);
	}
	}

	void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
	{
	if (destructor_key.sane != -1) {
	THREAD_EVENT_HANDLER **hands
	= init_get_thread_local(&destructor_key.value, 0, 1);
	init_thread_stop(ctx, hands);
	}
	}

	#else

	void ossl_thread_event_ctx_new(OSSL_LIB_CTX libctx)
	{
	THREAD_EVENT_HANDLER **hands = NULL;
	CRYPTO_THREAD_LOCAL tlocal = OPENSSL_zalloc(sizeof(tlocal));

	if (tlocal == NULL)
	return NULL;

	if (!CRYPTO_THREAD_init_local(tlocal, NULL)) {
	goto err;
	}

	hands = OPENSSL_zalloc(sizeof(*hands));
	if (hands == NULL)
	goto err;

	if (!CRYPTO_THREAD_set_local(tlocal, hands))
	goto err;

	return tlocal;
	err:
	OPENSSL_free(hands);
	OPENSSL_free(tlocal);
	return NULL;
	}

	void ossl_thread_event_ctx_free(void *tlocal)
	{
	OPENSSL_free(tlocal);
	}

	static void ossl_arg_thread_stop(void *arg)
	{
	ossl_ctx_thread_stop((OSSL_LIB_CTX *)arg);
	}

	void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
	{
	THREAD_EVENT_HANDLER **hands;
	CRYPTO_THREAD_LOCAL *local
	= ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);

	if (local == NULL)
	return;
	hands = init_get_thread_local(local, 0, 0);
	init_thread_stop(ctx, hands);
	OPENSSL_free(hands);
	}
	#endif /* FIPS_MODULE */


	static void init_thread_stop(void arg, THREAD_EVENT_HANDLER *hands)
	{
	THREAD_EVENT_HANDLER curr, prev = NULL, *tmp;
	#ifndef FIPS_MODULE
	GLOBAL_TEVENT_REGISTER *gtr;
	#endif

	/* Can't do much about this */
	if (hands == NULL)
	return;

	#ifndef FIPS_MODULE
	gtr = get_global_tevent_register();
	if (gtr == NULL)
	return;

	if (!CRYPTO_THREAD_write_lock(gtr->lock))
	return;
	#endif

	curr = *hands;
	while (curr != NULL) {
	if (arg != NULL && curr->arg != arg) {
	prev = curr;
	curr = curr->next;
	continue;
	}
	curr->handfn(curr->arg);
	if (prev == NULL)
	*hands = curr->next;
	else
	prev->next = curr->next;

	tmp = curr;
	curr = curr->next;

	OPENSSL_free(tmp);
	}
	#ifndef FIPS_MODULE
	CRYPTO_THREAD_unlock(gtr->lock);
	#endif
	}

	int ossl_init_thread_start(const void index, void arg,
	OSSL_thread_stop_handler_fn handfn)
	{
	THREAD_EVENT_HANDLER **hands;
	THREAD_EVENT_HANDLER *hand;
	#ifdef FIPS_MODULE
	OSSL_LIB_CTX *ctx = arg;

	/*
	* In FIPS mode the list of THREAD_EVENT_HANDLERs is unique per combination
	* of OSSL_LIB_CTX and thread. This is because in FIPS mode each
	* OSSL_LIB_CTX gets informed about thread stop events individually.
	*/
	CRYPTO_THREAD_LOCAL *local
	= ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);
	#else
	/*
	* Outside of FIPS mode the list of THREAD_EVENT_HANDLERs is unique per
	* thread, but may hold multiple OSSL_LIB_CTXs. We only get told about
	* thread stop events globally, so we have to ensure all affected
	* OSSL_LIB_CTXs are informed.
	*/
	CRYPTO_THREAD_LOCAL *local = &destructor_key.value;
	#endif

	hands = init_get_thread_local(local, 1, 0);
	if (hands == NULL)
	return 0;

	#ifdef FIPS_MODULE
	if (*hands == NULL) {
	/*
	* We've not yet registered any handlers for this thread. We need to get
	* libcrypto to tell us about later thread stop events. c_thread_start
	* is a callback to libcrypto defined in fipsprov.c
	*/
	if (!c_thread_start(FIPS_get_core_handle(ctx), ossl_arg_thread_stop,
	ctx))
	return 0;
	}
	#endif

	hand = OPENSSL_malloc(sizeof(*hand));
	if (hand == NULL)
	return 0;

	hand->handfn = handfn;
	hand->arg = arg;
	#ifndef FIPS_MODULE
	hand->index = index;
	#endif
	hand->next = *hands;
	*hands = hand;

	return 1;
	}

	#ifndef FIPS_MODULE
	static int init_thread_deregister(void *index, int all)
	{
	GLOBAL_TEVENT_REGISTER *gtr;
	int i;

	gtr = get_global_tevent_register();
	if (gtr == NULL)
	return 0;
	if (!all) {
	if (!CRYPTO_THREAD_write_lock(gtr->lock))
	return 0;
	} else {
	glob_tevent_reg = NULL;
	}
	for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
	THREAD_EVENT_HANDLER **hands
	= sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);
	THREAD_EVENT_HANDLER curr = NULL, prev = NULL, *tmp;

	if (hands == NULL) {
	if (!all)
	CRYPTO_THREAD_unlock(gtr->lock);
	return 0;
	}
	curr = *hands;
	while (curr != NULL) {
	if (all \|\| curr->index == index) {
	if (prev != NULL)
	prev->next = curr->next;
	else
	*hands = curr->next;
	tmp = curr;
	curr = curr->next;
	OPENSSL_free(tmp);
	continue;
	}
	prev = curr;
	curr = curr->next;
	}
	if (all)
	OPENSSL_free(hands);
	}
	if (all) {
	CRYPTO_THREAD_lock_free(gtr->lock);
	sk_THREAD_EVENT_HANDLER_PTR_free(gtr->skhands);
	OPENSSL_free(gtr);
	} else {
	CRYPTO_THREAD_unlock(gtr->lock);
	}
	return 1;
	}

	int ossl_init_thread_deregister(void *index)
	{
	return init_thread_deregister(index, 0);
	}
	#endif