/*

 * Copyright 2019 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_numbers.h>

#include "crypto/cryptlib.h"

#include "prov/providercommon.h"

#include "internal/thread_once.h"

#ifdef FIPS_MODE

/*

 * 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_core_thread_start_fn *c_thread_start;

#endif

typedef struct thread_event_handler_st THREAD_EVENT_HANDLER;

struct thread_event_handler_st {

    const void *index;

    void *arg;

    OSSL_thread_stop_handler_fn handfn;

    THREAD_EVENT_HANDLER *next;

};

#ifndef FIPS_MODE

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_MODE

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_MODE

            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_MODE

/*

 * 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;

    CRYPTO_THREAD_write_lock(gtr->lock);

    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;

    CRYPTO_THREAD_write_lock(gtr->lock);

    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) {

            hands = 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(OPENSSL_CTX *ctx)

{

    ctx = openssl_ctx_get_concrete(ctx);

    /*

     * TODO(3.0). It would be nice if we could figure out a way to do this on

     * all threads that have used the OPENSSL_CTX when the OPENSSL_CTX 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(void *arg)

{

    if (destructor_key.sane != -1) {

        THREAD_EVENT_HANDLER **hands

            = init_get_thread_local(&destructor_key.value, 0, 1);

        init_thread_stop(arg, hands);

    }

}

#else

static void *thread_event_ossl_ctx_new(OPENSSL_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;

}

static void thread_event_ossl_ctx_free(void *tlocal)

{

    OPENSSL_free(tlocal);

}

static const OPENSSL_CTX_METHOD thread_event_ossl_ctx_method = {

    thread_event_ossl_ctx_new,

    thread_event_ossl_ctx_free,

};

void ossl_ctx_thread_stop(void *arg)

{

    THREAD_EVENT_HANDLER **hands;

    OPENSSL_CTX *ctx = arg;

    CRYPTO_THREAD_LOCAL *local

        = openssl_ctx_get_data(ctx, OPENSSL_CTX_THREAD_EVENT_HANDLER_INDEX,

                               &thread_event_ossl_ctx_method);

    if (local == NULL)

        return;

    hands = init_get_thread_local(local, 0, 0);

    init_thread_stop(arg, hands);

    OPENSSL_free(hands);

}

#endif /* FIPS_MODE */

static void init_thread_stop(void *arg, THREAD_EVENT_HANDLER **hands)

{

    THREAD_EVENT_HANDLER *curr, *prev = NULL, *tmp;

    /* Can't do much about this */

    if (hands == NULL)

        return;

    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);

    }

}

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_MODE

    OPENSSL_CTX *ctx = arg;

    /*

     * In FIPS mode the list of THREAD_EVENT_HANDLERs is unique per combination

     * of OPENSSL_CTX and thread. This is because in FIPS mode each OPENSSL_CTX

     * gets informed about thread stop events individually.

     */

    CRYPTO_THREAD_LOCAL *local

        = openssl_ctx_get_data(ctx, OPENSSL_CTX_THREAD_EVENT_HANDLER_INDEX,

                               &thread_event_ossl_ctx_method);

#else

    /*

     * Outside of FIPS mode the list of THREAD_EVENT_HANDLERs is unique per

     * thread, but may hold multiple OPENSSL_CTXs. We only get told about

     * thread stop events globally, so we have to ensure all affected

     * OPENSSL_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_MODE

    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_provider(ctx), ossl_ctx_thread_stop))

            return 0;

    }

#endif

    hand = OPENSSL_malloc(sizeof(*hand));

    if (hand == NULL)

        return 0;

    hand->handfn = handfn;

    hand->arg = arg;

    hand->index = index;

    hand->next = *hands;

    *hands = hand;

    return 1;

}

#ifndef FIPS_MODE

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)

        CRYPTO_THREAD_write_lock(gtr->lock);

    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 = *hands, *prev = NULL, *tmp;

        if (hands == NULL) {

            if (!all)

                CRYPTO_THREAD_unlock(gtr->lock);

            return 0;

        }

        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