/*

 * Copyright 1995-2018 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 <stdio.h>

#include <time.h>

#include "internal/cryptlib.h"

#include <openssl/opensslconf.h>

#include "internal/rand_int.h"

#include <openssl/engine.h>

#include "internal/thread_once.h"

#include "rand_lcl.h"

#include "e_os.h"

#ifndef OPENSSL_NO_ENGINE

/* non-NULL if default_RAND_meth is ENGINE-provided */

static ENGINE *funct_ref;

static CRYPTO_RWLOCK *rand_engine_lock;

#endif

static CRYPTO_RWLOCK *rand_meth_lock;

static const RAND_METHOD *default_RAND_meth;

static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;

int rand_fork_count;

static CRYPTO_RWLOCK *rand_nonce_lock;

static int rand_nonce_count;

static int rand_cleaning_up = 0;

#ifdef OPENSSL_RAND_SEED_RDTSC

/*

 * IMPORTANT NOTE:  It is not currently possible to use this code

 * because we are not sure about the amount of randomness it provides.

 * Some SP900 tests have been run, but there is internal skepticism.

 * So for now this code is not used.

 */

# error "RDTSC enabled?  Should not be possible!"

/*

 * Acquire entropy from high-speed clock

 *

 * Since we get some randomness from the low-order bits of the

 * high-speed clock, it can help.

 *

 * Returns the total entropy count, if it exceeds the requested

 * entropy count. Otherwise, returns an entropy count of 0.

 */

size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)

{

    unsigned char c;

    int i;

    if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {

        for (i = 0; i < TSC_READ_COUNT; i++) {

            c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);

            rand_pool_add(pool, &c, 1, 4);

        }

    }

    return rand_pool_entropy_available(pool);

}

#endif

#ifdef OPENSSL_RAND_SEED_RDCPU

size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);

size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);

extern unsigned int OPENSSL_ia32cap_P[];

/*

 * Acquire entropy using Intel-specific cpu instructions

 *

 * Uses the RDSEED instruction if available, otherwise uses

 * RDRAND if available.

 *

 * For the differences between RDSEED and RDRAND, and why RDSEED

 * is the preferred choice, see https://goo.gl/oK3KcN

 *

 * Returns the total entropy count, if it exceeds the requested

 * entropy count. Otherwise, returns an entropy count of 0.

 */

size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)

{

    size_t bytes_needed;

    unsigned char *buffer;

    bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);

    if (bytes_needed > 0) {

        buffer = rand_pool_add_begin(pool, bytes_needed);

        if (buffer != NULL) {

            /* Whichever comes first, use RDSEED, RDRAND or nothing */

            if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {

                if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)

                    == bytes_needed) {

                    rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);

                }

            } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {

                if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)

                    == bytes_needed) {

                    rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);

                }

            } else {

                rand_pool_add_end(pool, 0, 0);

            }

        }

    }

    return rand_pool_entropy_available(pool);

}

#endif

/*

 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())

 *

 * If the DRBG has a parent, then the required amount of entropy input

 * is fetched using the parent's RAND_DRBG_generate().

 *

 * Otherwise, the entropy is polled from the system entropy sources

 * using rand_pool_acquire_entropy().

 *

 * If a random pool has been added to the DRBG using RAND_add(), then

 * its entropy will be used up first.

 */

size_t rand_drbg_get_entropy(RAND_DRBG *drbg,

                             unsigned char **pout,

                             int entropy, size_t min_len, size_t max_len,

                             int prediction_resistance)

{

    size_t ret = 0;

    size_t entropy_available = 0;

    RAND_POOL *pool;

    if (drbg->parent && drbg->strength > drbg->parent->strength) {

        /*

         * We currently don't support the algorithm from NIST SP 800-90C

         * 10.1.2 to use a weaker DRBG as source

         */

        RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);

        return 0;

    }

    pool = rand_pool_new(entropy, min_len, max_len);

    if (pool == NULL)

        return 0;

    if (drbg->pool) {

        rand_pool_add(pool,

                      rand_pool_buffer(drbg->pool),

                      rand_pool_length(drbg->pool),

                      rand_pool_entropy(drbg->pool));

        rand_pool_free(drbg->pool);

        drbg->pool = NULL;

    }

    if (drbg->parent) {

        size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);

        unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);

        if (buffer != NULL) {

            size_t bytes = 0;

            /*

             * Get random from parent, include our state as additional input.

             * Our lock is already held, but we need to lock our parent before

             * generating bits from it. (Note: taking the lock will be a no-op

             * if locking if drbg->parent->lock == NULL.)

             */

            rand_drbg_lock(drbg->parent);

            if (RAND_DRBG_generate(drbg->parent,

                                   buffer, bytes_needed,

                                   prediction_resistance,

                                   NULL, 0) != 0)

                bytes = bytes_needed;

            rand_drbg_unlock(drbg->parent);

            rand_pool_add_end(pool, bytes, 8 * bytes);

            entropy_available = rand_pool_entropy_available(pool);

        }

    } else {

        if (prediction_resistance) {

            /*

             * We don't have any entropy sources that comply with the NIST

             * standard to provide prediction resistance (see NIST SP 800-90C,

             * Section 5.4).

             */

            RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,

                    RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);

            goto err;

        }

        /* Get entropy by polling system entropy sources. */

        entropy_available = rand_pool_acquire_entropy(pool);

    }

    if (entropy_available > 0) {

        ret   = rand_pool_length(pool);

        *pout = rand_pool_detach(pool);

    }

 err:

    rand_pool_free(pool);

    return ret;

}

/*

 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())

 *

 */

void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,

                               unsigned char *out, size_t outlen)

{

    OPENSSL_secure_clear_free(out, outlen);

}

/*

 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())

 *

 */

size_t rand_drbg_get_nonce(RAND_DRBG *drbg,

                           unsigned char **pout,

                           int entropy, size_t min_len, size_t max_len)

{

    size_t ret = 0;

    RAND_POOL *pool;

    struct {

        void * instance;

        int count;

    } data = { 0 };

    pool = rand_pool_new(0, min_len, max_len);

    if (pool == NULL)

        return 0;

    if (rand_pool_add_nonce_data(pool) == 0)

        goto err;

    data.instance = drbg;

    CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);

    if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)

        goto err;

    ret   = rand_pool_length(pool);

    *pout = rand_pool_detach(pool);

 err:

    rand_pool_free(pool);

    return ret;

}

/*

 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())

 *

 */

void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,

                             unsigned char *out, size_t outlen)

{

    OPENSSL_secure_clear_free(out, outlen);

}

/*

 * Generate additional data that can be used for the drbg. The data does

 * not need to contain entropy, but it's useful if it contains at least

 * some bits that are unpredictable.

 *

 * Returns 0 on failure.

 *

 * On success it allocates a buffer at |*pout| and returns the length of

 * the data. The buffer should get freed using OPENSSL_secure_clear_free().

 */

size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)

{

    size_t ret = 0;

    RAND_POOL *pool;

    pool = rand_pool_new(0, 0, max_len);

    if (pool == NULL)

        return 0;

    if (rand_pool_add_additional_data(pool) == 0)

        goto err;

    ret = rand_pool_length(pool);

    *pout = rand_pool_detach(pool);

 err:

    rand_pool_free(pool);

    return ret;

}

void rand_drbg_cleanup_additional_data(unsigned char *out, size_t outlen)

{

    OPENSSL_secure_clear_free(out, outlen);

}

void rand_fork(void)

{

    rand_fork_count++;

}

DEFINE_RUN_ONCE_STATIC(do_rand_init)

{

#ifndef OPENSSL_NO_ENGINE

    rand_engine_lock = CRYPTO_THREAD_lock_new();

    if (rand_engine_lock == NULL)

        return 0;

#endif

    rand_meth_lock = CRYPTO_THREAD_lock_new();

    if (rand_meth_lock == NULL)

        goto err1;

    rand_nonce_lock = CRYPTO_THREAD_lock_new();

    if (rand_nonce_lock == NULL)

        goto err2;

    if (!rand_cleaning_up && !rand_pool_init())

        goto err3;

    return 1;

err3:

    rand_pool_cleanup();

err2:

    CRYPTO_THREAD_lock_free(rand_meth_lock);

    rand_meth_lock = NULL;

err1:

#ifndef OPENSSL_NO_ENGINE

    CRYPTO_THREAD_lock_free(rand_engine_lock);

    rand_engine_lock = NULL;

#endif

    return 0;

}

void rand_cleanup_int(void)

{

    const RAND_METHOD *meth = default_RAND_meth;

    rand_cleaning_up = 1;

    if (meth != NULL && meth->cleanup != NULL)

        meth->cleanup();

    RAND_set_rand_method(NULL);

    rand_pool_cleanup();

#ifndef OPENSSL_NO_ENGINE

    CRYPTO_THREAD_lock_free(rand_engine_lock);

    rand_engine_lock = NULL;

#endif

    CRYPTO_THREAD_lock_free(rand_meth_lock);

    rand_meth_lock = NULL;

    CRYPTO_THREAD_lock_free(rand_nonce_lock);

    rand_nonce_lock = NULL;

}

/*

 * RAND_close_seed_files() ensures that any seed file decriptors are

 * closed after use.

 */

void RAND_keep_random_devices_open(int keep)

{

    rand_pool_keep_random_devices_open(keep);

}

/*

 * RAND_poll() reseeds the default RNG using random input

 *

 * The random input is obtained from polling various entropy

 * sources which depend on the operating system and are

 * configurable via the --with-rand-seed configure option.

 */

int RAND_poll(void)

{

    int ret = 0;

    RAND_POOL *pool = NULL;

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth == RAND_OpenSSL()) {

        /* fill random pool and seed the master DRBG */

        RAND_DRBG *drbg = RAND_DRBG_get0_master();

        if (drbg == NULL)

            return 0;

        rand_drbg_lock(drbg);

        ret = rand_drbg_restart(drbg, NULL, 0, 0);

        rand_drbg_unlock(drbg);

        return ret;

    } else {

        /* fill random pool and seed the current legacy RNG */

        pool = rand_pool_new(RAND_DRBG_STRENGTH,

                             RAND_DRBG_STRENGTH / 8,

                             DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));

        if (pool == NULL)

            return 0;

        if (rand_pool_acquire_entropy(pool) == 0)

            goto err;

        if (meth->add == NULL

            || meth->add(rand_pool_buffer(pool),

                         rand_pool_length(pool),

                         (rand_pool_entropy(pool) / 8.0)) == 0)

            goto err;

        ret = 1;

    }

err:

    rand_pool_free(pool);

    return ret;

}

/*

 * Allocate memory and initialize a new random pool

 */

RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)

{

    RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));

    if (pool == NULL) {

        RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    pool->min_len = min_len;

    pool->max_len = max_len;

    pool->buffer = OPENSSL_secure_zalloc(pool->max_len);

    if (pool->buffer == NULL) {

        RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    pool->requested_entropy = entropy;

    return pool;

err:

    OPENSSL_free(pool);

    return NULL;

}

/*

 * Free |pool|, securely erasing its buffer.

 */

void rand_pool_free(RAND_POOL *pool)

{

    if (pool == NULL)

        return;

    OPENSSL_secure_clear_free(pool->buffer, pool->max_len);

    OPENSSL_free(pool);

}

/*

 * Return the |pool|'s buffer to the caller (readonly).

 */

const unsigned char *rand_pool_buffer(RAND_POOL *pool)

{

    return pool->buffer;

}

/*

 * Return the |pool|'s entropy to the caller.

 */

size_t rand_pool_entropy(RAND_POOL *pool)

{

    return pool->entropy;

}

/*

 * Return the |pool|'s buffer length to the caller.

 */

size_t rand_pool_length(RAND_POOL *pool)

{

    return pool->len;

}

/*

 * Detach the |pool| buffer and return it to the caller.

 * It's the responsibility of the caller to free the buffer

 * using OPENSSL_secure_clear_free().

 */

unsigned char *rand_pool_detach(RAND_POOL *pool)

{

    unsigned char *ret = pool->buffer;

    pool->buffer = NULL;

    return ret;

}

/*

 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one

 * need to obtain at least |bits| bits of entropy?

 */

#define ENTROPY_TO_BYTES(bits, entropy_factor) \

    (((bits) * (entropy_factor) + 7) / 8)

/*

 * Checks whether the |pool|'s entropy is available to the caller.

 * This is the case when entropy count and buffer length are high enough.

 * Returns

 *

 *  |entropy|  if the entropy count and buffer size is large enough

 *      0      otherwise

 */

size_t rand_pool_entropy_available(RAND_POOL *pool)

{

    if (pool->entropy < pool->requested_entropy)

        return 0;

    if (pool->len < pool->min_len)

        return 0;

    return pool->entropy;

}

/*

 * Returns the (remaining) amount of entropy needed to fill

 * the random pool.

 */

size_t rand_pool_entropy_needed(RAND_POOL *pool)

{

    if (pool->entropy < pool->requested_entropy)

        return pool->requested_entropy - pool->entropy;

    return 0;

}

/*

 * Returns the number of bytes needed to fill the pool, assuming

 * the input has 1 / |entropy_factor| entropy bits per data bit.

 * In case of an error, 0 is returned.

 */

size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)

{

    size_t bytes_needed;

    size_t entropy_needed = rand_pool_entropy_needed(pool);

    if (entropy_factor < 1) {

        RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);

        return 0;

    }

    bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);

    if (bytes_needed > pool->max_len - pool->len) {

        /* not enough space left */

        RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);

        return 0;

    }

    if (pool->len < pool->min_len &&

        bytes_needed < pool->min_len - pool->len)

        /* to meet the min_len requirement */

        bytes_needed = pool->min_len - pool->len;

    return bytes_needed;

}

/* Returns the remaining number of bytes available */

size_t rand_pool_bytes_remaining(RAND_POOL *pool)

{

    return pool->max_len - pool->len;

}

/*

 * Add random bytes to the random pool.

 *

 * It is expected that the |buffer| contains |len| bytes of

 * random input which contains at least |entropy| bits of

 * randomness.

 *

 * Returns 1 if the added amount is adequate, otherwise 0

 */

int rand_pool_add(RAND_POOL *pool,

                  const unsigned char *buffer, size_t len, size_t entropy)

{

    if (len > pool->max_len - pool->len) {

        RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);

        return 0;

    }

    if (len > 0) {

        memcpy(pool->buffer + pool->len, buffer, len);

        pool->len += len;

        pool->entropy += entropy;

    }

    return 1;

}

/*

 * Start to add random bytes to the random pool in-place.

 *

 * Reserves the next |len| bytes for adding random bytes in-place

 * and returns a pointer to the buffer.

 * The caller is allowed to copy up to |len| bytes into the buffer.

 * If |len| == 0 this is considered a no-op and a NULL pointer

 * is returned without producing an error message.

 *

 * After updating the buffer, rand_pool_add_end() needs to be called

 * to finish the udpate operation (see next comment).

 */

unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)

{

    if (len == 0)

        return NULL;

    if (len > pool->max_len - pool->len) {

        RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);

        return NULL;

    }

    return pool->buffer + pool->len;

}

/*

 * Finish to add random bytes to the random pool in-place.

 *

 * Finishes an in-place update of the random pool started by

 * rand_pool_add_begin() (see previous comment).

 * It is expected that |len| bytes of random input have been added

 * to the buffer which contain at least |entropy| bits of randomness.

 * It is allowed to add less bytes than originally reserved.

 */

int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)

{

    if (len > pool->max_len - pool->len) {

        RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);

        return 0;

    }

    if (len > 0) {

        pool->len += len;

        pool->entropy += entropy;

    }

    return 1;

}

int RAND_set_rand_method(const RAND_METHOD *meth)

{

    if (!RUN_ONCE(&rand_init, do_rand_init))

        return 0;

    CRYPTO_THREAD_write_lock(rand_meth_lock);

#ifndef OPENSSL_NO_ENGINE

    ENGINE_finish(funct_ref);

    funct_ref = NULL;

#endif

    default_RAND_meth = meth;

    CRYPTO_THREAD_unlock(rand_meth_lock);

    return 1;

}

const RAND_METHOD *RAND_get_rand_method(void)

{

    const RAND_METHOD *tmp_meth = NULL;

    if (!RUN_ONCE(&rand_init, do_rand_init))

        return NULL;

    CRYPTO_THREAD_write_lock(rand_meth_lock);

    if (default_RAND_meth == NULL) {

#ifndef OPENSSL_NO_ENGINE

        ENGINE *e;

        /* If we have an engine that can do RAND, use it. */

        if ((e = ENGINE_get_default_RAND()) != NULL

                && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {

            funct_ref = e;

            default_RAND_meth = tmp_meth;

        } else {

            ENGINE_finish(e);

            default_RAND_meth = &rand_meth;

        }

#else

        default_RAND_meth = &rand_meth;

#endif

    }

    tmp_meth = default_RAND_meth;

    CRYPTO_THREAD_unlock(rand_meth_lock);

    return tmp_meth;

}

#ifndef OPENSSL_NO_ENGINE

int RAND_set_rand_engine(ENGINE *engine)

{

    const RAND_METHOD *tmp_meth = NULL;

    if (!RUN_ONCE(&rand_init, do_rand_init))

        return 0;

    if (engine != NULL) {

        if (!ENGINE_init(engine))

            return 0;

        tmp_meth = ENGINE_get_RAND(engine);

        if (tmp_meth == NULL) {

            ENGINE_finish(engine);

            return 0;

        }

    }

    CRYPTO_THREAD_write_lock(rand_engine_lock);

    /* This function releases any prior ENGINE so call it first */

    RAND_set_rand_method(tmp_meth);

    funct_ref = engine;

    CRYPTO_THREAD_unlock(rand_engine_lock);

    return 1;

}

#endif

void RAND_seed(const void *buf, int num)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth->seed != NULL)

        meth->seed(buf, num);

}

void RAND_add(const void *buf, int num, double randomness)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth->add != NULL)

        meth->add(buf, num, randomness);

}

/*

 * This function is not part of RAND_METHOD, so if we're not using

 * the default method, then just call RAND_bytes().  Otherwise make

 * sure we're instantiated and use the private DRBG.

 */

int RAND_priv_bytes(unsigned char *buf, int num)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    RAND_DRBG *drbg;

    int ret;

    if (meth != RAND_OpenSSL())

        return RAND_bytes(buf, num);

    drbg = RAND_DRBG_get0_private();

    if (drbg == NULL)

        return 0;

    ret = RAND_DRBG_bytes(drbg, buf, num);

    return ret;

}

int RAND_bytes(unsigned char *buf, int num)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth->bytes != NULL)

        return meth->bytes(buf, num);

    RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);

    return -1;

}

#if OPENSSL_API_COMPAT < 0x10100000L

int RAND_pseudo_bytes(unsigned char *buf, int num)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth->pseudorand != NULL)

        return meth->pseudorand(buf, num);

    return -1;

}

#endif

int RAND_status(void)

{

    const RAND_METHOD *meth = RAND_get_rand_method();

    if (meth->status != NULL)

        return meth->status();

    return 0;

}