openssl/crypto/ex_data.c

/*
 * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (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 "crypto/cryptlib.h"
#include "internal/thread_once.h"

/*
 * Each structure type (sometimes called a class), that supports
 * exdata has a stack of callbacks for each instance.
 */
struct ex_callback_st {
    long argl;                  /* Arbitrary long */
    void *argp;                 /* Arbitrary void * */
    CRYPTO_EX_new *new_func;
    CRYPTO_EX_free *free_func;
    CRYPTO_EX_dup *dup_func;
};

/*
 * The state for each class.  This could just be a typedef, but
 * a structure allows future changes.
 */
typedef struct ex_callbacks_st {
    STACK_OF(EX_CALLBACK) *meth;
} EX_CALLBACKS;

static EX_CALLBACKS ex_data[CRYPTO_EX_INDEX__COUNT];

static CRYPTO_RWLOCK *ex_data_lock = NULL;
static CRYPTO_ONCE ex_data_init = CRYPTO_ONCE_STATIC_INIT;

DEFINE_RUN_ONCE_STATIC(do_ex_data_init)
{
    if (!OPENSSL_init_crypto(0, NULL))
        return 0;
    ex_data_lock = CRYPTO_THREAD_lock_new();
    return ex_data_lock != NULL;
}

/*
 * Return the EX_CALLBACKS from the |ex_data| array that corresponds to
 * a given class.  On success, *holds the lock.*
 */
static EX_CALLBACKS *get_and_lock(int class_index)
{
    EX_CALLBACKS *ip;

    if (class_index < 0 || class_index >= CRYPTO_EX_INDEX__COUNT) {
        CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_PASSED_INVALID_ARGUMENT);
        return NULL;
    }

    if (!RUN_ONCE(&ex_data_init, do_ex_data_init)) {
        CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    if (ex_data_lock == NULL) {
        /*
         * This can happen in normal operation when using CRYPTO_mem_leaks().
         * The CRYPTO_mem_leaks() function calls OPENSSL_cleanup() which cleans
         * up the locks. Subsequently the BIO that CRYPTO_mem_leaks() uses gets
         * freed, which also attempts to free the ex_data. However
         * CRYPTO_mem_leaks() ensures that the ex_data is freed early (i.e.
         * before OPENSSL_cleanup() is called), so if we get here we can safely
         * ignore this operation. We just treat it as an error.
         */
         return NULL;
    }

    ip = &ex_data[class_index];
    CRYPTO_THREAD_write_lock(ex_data_lock);
    return ip;
}

static void cleanup_cb(EX_CALLBACK *funcs)
{
    OPENSSL_free(funcs);
}

/*
 * Release all "ex_data" state to prevent memory leaks. This can't be made
 * thread-safe without overhauling a lot of stuff, and shouldn't really be
 * called under potential race-conditions anyway (it's for program shutdown
 * after all).
 */
void crypto_cleanup_all_ex_data_int(void)
{
    int i;

    for (i = 0; i < CRYPTO_EX_INDEX__COUNT; ++i) {
        EX_CALLBACKS *ip = &ex_data[i];

        sk_EX_CALLBACK_pop_free(ip->meth, cleanup_cb);
        ip->meth = NULL;
    }

    CRYPTO_THREAD_lock_free(ex_data_lock);
    ex_data_lock = NULL;
}


/*
 * Unregister a new index by replacing the callbacks with no-ops.
 * Any in-use instances are leaked.
 */
static void dummy_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
                     long argl, void *argp)
{
}

static void dummy_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
                       long argl, void *argp)
{
}

static int dummy_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
                     void *from_d, int idx,
                     long argl, void *argp)
{
    return 1;
}

int CRYPTO_free_ex_index(int class_index, int idx)
{
    EX_CALLBACKS *ip = get_and_lock(class_index);
    EX_CALLBACK *a;
    int toret = 0;

    if (ip == NULL)
        return 0;
    if (idx < 0 || idx >= sk_EX_CALLBACK_num(ip->meth))
        goto err;
    a = sk_EX_CALLBACK_value(ip->meth, idx);
    if (a == NULL)
        goto err;
    a->new_func = dummy_new;
    a->dup_func = dummy_dup;
    a->free_func = dummy_free;
    toret = 1;
err:
    CRYPTO_THREAD_unlock(ex_data_lock);
    return toret;
}

/*
 * Register a new index.
 */
int CRYPTO_get_ex_new_index(int class_index, long argl, void *argp,
                            CRYPTO_EX_new *new_func, CRYPTO_EX_dup *dup_func,
                            CRYPTO_EX_free *free_func)
{
    int toret = -1;
    EX_CALLBACK *a;
    EX_CALLBACKS *ip = get_and_lock(class_index);

    if (ip == NULL)
        return -1;

    if (ip->meth == NULL) {
        ip->meth = sk_EX_CALLBACK_new_null();
        /* We push an initial value on the stack because the SSL
         * "app_data" routines use ex_data index zero.  See RT 3710. */
        if (ip->meth == NULL
            || !sk_EX_CALLBACK_push(ip->meth, NULL)) {
            CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
            goto err;
        }
    }

    a = (EX_CALLBACK *)OPENSSL_malloc(sizeof(*a));
    if (a == NULL) {
        CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    a->argl = argl;
    a->argp = argp;
    a->new_func = new_func;
    a->dup_func = dup_func;
    a->free_func = free_func;

    if (!sk_EX_CALLBACK_push(ip->meth, NULL)) {
        CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
        OPENSSL_free(a);
        goto err;
    }
    toret = sk_EX_CALLBACK_num(ip->meth) - 1;
    (void)sk_EX_CALLBACK_set(ip->meth, toret, a);

 err:
    CRYPTO_THREAD_unlock(ex_data_lock);
    return toret;
}

/*
 * Initialise a new CRYPTO_EX_DATA for use in a particular class - including
 * calling new() callbacks for each index in the class used by this variable
 * Thread-safe by copying a class's array of "EX_CALLBACK" entries
 * in the lock, then using them outside the lock. Note this only applies
 * to the global "ex_data" state (ie. class definitions), not 'ad' itself.
 */
int CRYPTO_new_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
{
    int mx, i;
    void *ptr;
    EX_CALLBACK **storage = NULL;
    EX_CALLBACK *stack[10];
    EX_CALLBACKS *ip = get_and_lock(class_index);

    if (ip == NULL)
        return 0;

    ad->sk = NULL;

    mx = sk_EX_CALLBACK_num(ip->meth);
    if (mx > 0) {
        if (mx < (int)OSSL_NELEM(stack))
            storage = stack;
        else
            storage = OPENSSL_malloc(sizeof(*storage) * mx);
        if (storage != NULL)
            for (i = 0; i < mx; i++)
                storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
    }
    CRYPTO_THREAD_unlock(ex_data_lock);

    if (mx > 0 && storage == NULL) {
        CRYPTOerr(CRYPTO_F_CRYPTO_NEW_EX_DATA, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    for (i = 0; i < mx; i++) {
        if (storage[i] != NULL && storage[i]->new_func != NULL) {
            ptr = CRYPTO_get_ex_data(ad, i);
            storage[i]->new_func(obj, ptr, ad, i,
                                 storage[i]->argl, storage[i]->argp);
        }
    }
    if (storage != stack)
        OPENSSL_free(storage);
    return 1;
}

/*
 * Duplicate a CRYPTO_EX_DATA variable - including calling dup() callbacks
 * for each index in the class used by this variable
 */
int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
                       const CRYPTO_EX_DATA *from)
{
    int mx, j, i;
    void *ptr;
    EX_CALLBACK *stack[10];
    EX_CALLBACK **storage = NULL;
    EX_CALLBACKS *ip;
    int toret = 0;

    if (from->sk == NULL)
        /* Nothing to copy over */
        return 1;
    if ((ip = get_and_lock(class_index)) == NULL)
        return 0;

    mx = sk_EX_CALLBACK_num(ip->meth);
    j = sk_void_num(from->sk);
    if (j < mx)
        mx = j;
    if (mx > 0) {
        if (mx < (int)OSSL_NELEM(stack))
            storage = stack;
        else
            storage = OPENSSL_malloc(sizeof(*storage) * mx);
        if (storage != NULL)
            for (i = 0; i < mx; i++)
                storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
    }
    CRYPTO_THREAD_unlock(ex_data_lock);

    if (mx == 0)
        return 1;
    if (storage == NULL) {
        CRYPTOerr(CRYPTO_F_CRYPTO_DUP_EX_DATA, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    /*
     * Make sure the ex_data stack is at least |mx| elements long to avoid
     * issues in the for loop that follows; so go get the |mx|'th element
     * (if it does not exist CRYPTO_get_ex_data() returns NULL), and assign
     * to itself. This is normally a no-op; but ensures the stack is the
     * proper size
     */
    if (!CRYPTO_set_ex_data(to, mx - 1, CRYPTO_get_ex_data(to, mx - 1)))
        goto err;

    for (i = 0; i < mx; i++) {
        ptr = CRYPTO_get_ex_data(from, i);
        if (storage[i] != NULL && storage[i]->dup_func != NULL)
            if (!storage[i]->dup_func(to, from, &ptr, i,
                                      storage[i]->argl, storage[i]->argp))
                goto err;
        CRYPTO_set_ex_data(to, i, ptr);
    }
    toret = 1;
 err:
    if (storage != stack)
        OPENSSL_free(storage);
    return toret;
}


/*
 * Cleanup a CRYPTO_EX_DATA variable - including calling free() callbacks for
 * each index in the class used by this variable
 */
void CRYPTO_free_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
{
    int mx, i;
    EX_CALLBACKS *ip;
    void *ptr;
    EX_CALLBACK *f;
    EX_CALLBACK *stack[10];
    EX_CALLBACK **storage = NULL;

    if ((ip = get_and_lock(class_index)) == NULL)
        goto err;

    mx = sk_EX_CALLBACK_num(ip->meth);
    if (mx > 0) {
        if (mx < (int)OSSL_NELEM(stack))
            storage = stack;
        else
            storage = OPENSSL_malloc(sizeof(*storage) * mx);
        if (storage != NULL)
            for (i = 0; i < mx; i++)
                storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
    }
    CRYPTO_THREAD_unlock(ex_data_lock);

    for (i = 0; i < mx; i++) {
        if (storage != NULL)
            f = storage[i];
        else {
            CRYPTO_THREAD_write_lock(ex_data_lock);
            f = sk_EX_CALLBACK_value(ip->meth, i);
            CRYPTO_THREAD_unlock(ex_data_lock);
        }
        if (f != NULL && f->free_func != NULL) {
            ptr = CRYPTO_get_ex_data(ad, i);
            f->free_func(obj, ptr, ad, i, f->argl, f->argp);
        }
    }

    if (storage != stack)
        OPENSSL_free(storage);
 err:
    sk_void_free(ad->sk);
    ad->sk = NULL;
}

/*
 * For a given CRYPTO_EX_DATA variable, set the value corresponding to a
 * particular index in the class used by this variable
 */
int CRYPTO_set_ex_data(CRYPTO_EX_DATA *ad, int idx, void *val)
{
    int i;

    if (ad->sk == NULL) {
        if ((ad->sk = sk_void_new_null()) == NULL) {
            CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
            return 0;
        }
    }

    for (i = sk_void_num(ad->sk); i <= idx; ++i) {
        if (!sk_void_push(ad->sk, NULL)) {
            CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
            return 0;
        }
    }
    sk_void_set(ad->sk, idx, val);
    return 1;
}

/*
 * For a given CRYPTO_EX_DATA_ variable, get the value corresponding to a
 * particular index in the class used by this variable
 */
void *CRYPTO_get_ex_data(const CRYPTO_EX_DATA *ad, int idx)
{
    if (ad->sk == NULL || idx >= sk_void_num(ad->sk))
        return NULL;
    return sk_void_value(ad->sk, idx);
}