/src/openssl/crypto/rand/rand_pool.c

Source
/*
 * Copyright 1995-2021 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 <stdio.h>
#include <time.h>
#include "internal/cryptlib.h"
#include <openssl/opensslconf.h>
#include "crypto/rand.h"
#include "internal/thread_once.h"
#include "crypto/rand_pool.h"

/*
 * Allocate memory and initialize a new random pool
 */
RAND_POOL *ossl_rand_pool_new(int entropy_requested, int secure,
                              size_t min_len, size_t max_len)
{
    RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
    size_t min_alloc_size = RAND_POOL_MIN_ALLOCATION(secure);

    if (pool == NULL)
        return NULL;

    pool->min_len = min_len;
    pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
        RAND_POOL_MAX_LENGTH : max_len;
    pool->alloc_len = min_len < min_alloc_size ? min_alloc_size : min_len;
    if (pool->alloc_len > pool->max_len)
        pool->alloc_len = pool->max_len;

    if (secure)
        pool->buffer = OPENSSL_secure_zalloc(pool->alloc_len);
    else
        pool->buffer = OPENSSL_zalloc(pool->alloc_len);

    if (pool->buffer == NULL)
        goto err;

    pool->entropy_requested = entropy_requested;
    pool->secure = secure;
    return pool;

err:
    OPENSSL_free(pool);
    return NULL;
}

/*
 * Attach new random pool to the given buffer
 *
 * This function is intended to be used only for feeding random data
 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
 */
RAND_POOL *ossl_rand_pool_attach(const unsigned char *buffer, size_t len,
                                 size_t entropy)
{
    RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));

    if (pool == NULL)
        return NULL;

    /*
     * The const needs to be cast away, but attached buffers will not be
     * modified (in contrary to allocated buffers which are zeroed and
     * freed in the end).
     */
    pool->buffer = (unsigned char *) buffer;
    pool->len = len;

    pool->attached = 1;

    pool->min_len = pool->max_len = pool->alloc_len = pool->len;
    pool->entropy = entropy;

    return pool;
}

/*
 * Free |pool|, securely erasing its buffer.
 */
void ossl_rand_pool_free(RAND_POOL *pool)
{
    if (pool == NULL)
        return;

    /*
     * Although it would be advisable from a cryptographical viewpoint,
     * we are not allowed to clear attached buffers, since they are passed
     * to ossl_rand_pool_attach() as `const unsigned char*`.
     * (see corresponding comment in ossl_rand_pool_attach()).
     */
    if (!pool->attached) {
        if (pool->secure)
            OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
        else
            OPENSSL_clear_free(pool->buffer, pool->alloc_len);
    }

    OPENSSL_free(pool);
}

/*
 * Return the |pool|'s buffer to the caller (readonly).
 */
const unsigned char *ossl_rand_pool_buffer(RAND_POOL *pool)
{
    return pool->buffer;
}

/*
 * Return the |pool|'s entropy to the caller.
 */
size_t ossl_rand_pool_entropy(RAND_POOL *pool)
{
    return pool->entropy;
}

/*
 * Return the |pool|'s buffer length to the caller.
 */
size_t ossl_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() or to re-attach it
 * again to the pool using ossl_rand_pool_reattach().
 */
unsigned char *ossl_rand_pool_detach(RAND_POOL *pool)
{
    unsigned char *ret = pool->buffer;
    pool->buffer = NULL;
    pool->entropy = 0;
    return ret;
}

/*
 * Re-attach the |pool| buffer. It is only allowed to pass
 * the |buffer| which was previously detached from the same pool.
 */
void ossl_rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
{
    pool->buffer = buffer;
    OPENSSL_cleanse(pool->buffer, pool->len);
    pool->len = 0;
}

/*
 * 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 ossl_rand_pool_entropy_available(RAND_POOL *pool)
{
    if (pool->entropy < pool->entropy_requested)
        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 ossl_rand_pool_entropy_needed(RAND_POOL *pool)
{
    if (pool->entropy < pool->entropy_requested)
        return pool->entropy_requested - pool->entropy;

    return 0;
}

/* Increase the allocation size -- not usable for an attached pool */
static int rand_pool_grow(RAND_POOL *pool, size_t len)
{
    if (len > pool->alloc_len - pool->len) {
        unsigned char *p;
        const size_t limit = pool->max_len / 2;
        size_t newlen = pool->alloc_len;

        if (pool->attached || len > pool->max_len - pool->len) {
            ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
            return 0;
        }

        do
            newlen = newlen < limit ? newlen * 2 : pool->max_len;
        while (len > newlen - pool->len);

        if (pool->secure)
            p = OPENSSL_secure_zalloc(newlen);
        else
            p = OPENSSL_zalloc(newlen);
        if (p == NULL)
            return 0;
        memcpy(p, pool->buffer, pool->len);
        if (pool->secure)
            OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
        else
            OPENSSL_clear_free(pool->buffer, pool->alloc_len);
        pool->buffer = p;
        pool->alloc_len = newlen;
    }
    return 1;
}

/*
 * 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 ossl_rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
{
    size_t bytes_needed;
    size_t entropy_needed = ossl_rand_pool_entropy_needed(pool);

    if (entropy_factor < 1) {
        ERR_raise(ERR_LIB_RAND, 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 */
        ERR_raise_data(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW,
                       "entropy_factor=%u, entropy_needed=%zu, bytes_needed=%zu,"
                       "pool->max_len=%zu, pool->len=%zu",
                       entropy_factor, entropy_needed, bytes_needed,
                       pool->max_len, pool->len);
        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;

    /*
     * Make sure the buffer is large enough for the requested amount
     * of data. This guarantees that existing code patterns where
     * ossl_rand_pool_add_begin, ossl_rand_pool_add_end or ossl_rand_pool_add
     * are used to collect entropy data without any error handling
     * whatsoever, continue to be valid.
     * Furthermore if the allocation here fails once, make sure that
     * we don't fall back to a less secure or even blocking random source,
     * as that could happen by the existing code patterns.
     * This is not a concern for additional data, therefore that
     * is not needed if rand_pool_grow fails in other places.
     */
    if (!rand_pool_grow(pool, bytes_needed)) {
        /* persistent error for this pool */
        pool->max_len = pool->len = 0;
        return 0;
    }

    return bytes_needed;
}

/* Returns the remaining number of bytes available */
size_t ossl_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 ossl_rand_pool_add(RAND_POOL *pool,
                  const unsigned char *buffer, size_t len, size_t entropy)
{
    if (len > pool->max_len - pool->len) {
        ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG);
        return 0;
    }

    if (pool->buffer == NULL) {
        ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
        return 0;
    }

    if (len > 0) {
        /*
         * This is to protect us from accidentally passing the buffer
         * returned from ossl_rand_pool_add_begin.
         * The check for alloc_len makes sure we do not compare the
         * address of the end of the allocated memory to something
         * different, since that comparison would have an
         * indeterminate result.
         */
        if (pool->alloc_len > pool->len && pool->buffer + pool->len == buffer) {
            ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
            return 0;
        }
        /*
         * We have that only for cases when a pool is used to collect
         * additional data.
         * For entropy data, as long as the allocation request stays within
         * the limits given by ossl_rand_pool_bytes_needed this rand_pool_grow
         * below is guaranteed to succeed, thus no allocation happens.
         */
        if (!rand_pool_grow(pool, len))
            return 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, ossl_rand_pool_add_end() needs to be called
 * to finish the update operation (see next comment).
 */
unsigned char *ossl_rand_pool_add_begin(RAND_POOL *pool, size_t len)
{
    if (len == 0)
        return NULL;

    if (len > pool->max_len - pool->len) {
        ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW);
        return NULL;
    }

    if (pool->buffer == NULL) {
        ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
        return NULL;
    }

    /*
     * As long as the allocation request stays within the limits given
     * by ossl_rand_pool_bytes_needed this rand_pool_grow below is guaranteed
     * to succeed, thus no allocation happens.
     * We have that only for cases when a pool is used to collect
     * additional data. Then the buffer might need to grow here,
     * and of course the caller is responsible to check the return
     * value of this function.
     */
    if (!rand_pool_grow(pool, len))
        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
 * ossl_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 ossl_rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
{
    if (len > pool->alloc_len - pool->len) {
        ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW);
        return 0;
    }

    if (len > 0) {
        pool->len += len;
        pool->entropy += entropy;
    }

    return 1;
}

/**
 * @brief Mix in the additional input into an existing entropy in the pool
 *
 * @param pool     A RAND_POOL to mix the additional input in
 * @param adin     A buffer with the additional input
 * @param adin_len A length of the additional input
 *
 * @return 1 if there is any existing entropy in the pool so the additional input
 *         can be mixed in, 0 otherwise.
 */

int ossl_rand_pool_adin_mix_in(RAND_POOL *pool, const unsigned char *adin,
                               size_t adin_len)
{
    if (adin == NULL || adin_len == 0)
        /* Nothing to mix in -> success */
        return 1;

    if (pool->buffer == NULL) {
        ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
        return 0;
    }

    if (pool->len == 0) {
        ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_IS_EMPTY);
        return 0;
    }

    if (adin != NULL && adin_len > 0) {
        size_t i;

        /* xor the additional data into the pool */
        for (i = 0; i < adin_len; ++i)
            pool->buffer[i % pool->len] ^= adin[i];
    }

    return 1;
}

Coverage Report

Created: 2025-12-08 06:22

Line	Count	Source
1		/*
2		* Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
3		*
4		* Licensed under the Apache License 2.0 (the "License"). You may not use
5		* this file except in compliance with the License. You can obtain a copy
6		* in the file LICENSE in the source distribution or at
7		* https://www.openssl.org/source/license.html
8		*/
9
10		#include <stdio.h>
11		#include <time.h>
12		#include "internal/cryptlib.h"
13		#include <openssl/opensslconf.h>
14		#include "crypto/rand.h"
15		#include "internal/thread_once.h"
16		#include "crypto/rand_pool.h"
17
18		/*
19		* Allocate memory and initialize a new random pool
20		*/
21		RAND_POOL *ossl_rand_pool_new(int entropy_requested, int secure,
22		size_t min_len, size_t max_len)
23	48	{
24	48	RAND_POOL pool = OPENSSL_zalloc(sizeof(pool));
25	48	size_t min_alloc_size = RAND_POOL_MIN_ALLOCATION(secure);
26
27	48	if (pool == NULL)
28	0	return NULL;
29
30	48	pool->min_len = min_len;
31	48	pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
32	48	RAND_POOL_MAX_LENGTH : max_len;
33	48	pool->alloc_len = min_len < min_alloc_size ? min_alloc_size : min_len;
34	48	if (pool->alloc_len > pool->max_len)
35	0	pool->alloc_len = pool->max_len;
36
37	48	if (secure)
38	48	pool->buffer = OPENSSL_secure_zalloc(pool->alloc_len);
39	0	else
40	0	pool->buffer = OPENSSL_zalloc(pool->alloc_len);
41
42	48	if (pool->buffer == NULL)
43	0	goto err;
44
45	48	pool->entropy_requested = entropy_requested;
46	48	pool->secure = secure;
47	48	return pool;
48
49	0	err:
50	0	OPENSSL_free(pool);
51	0	return NULL;
52	48	}
53
54		/*
55		* Attach new random pool to the given buffer
56		*
57		* This function is intended to be used only for feeding random data
58		* provided by RAND_add() and RAND_seed() into the <master> DRBG.
59		*/
60		RAND_POOL ossl_rand_pool_attach(const unsigned char buffer, size_t len,
61		size_t entropy)
62	0	{
63	0	RAND_POOL pool = OPENSSL_zalloc(sizeof(pool));
64
65	0	if (pool == NULL)
66	0	return NULL;
67
68		/*
69		* The const needs to be cast away, but attached buffers will not be
70		* modified (in contrary to allocated buffers which are zeroed and
71		* freed in the end).
72		*/
73	0	pool->buffer = (unsigned char *) buffer;
74	0	pool->len = len;
75
76	0	pool->attached = 1;
77
78	0	pool->min_len = pool->max_len = pool->alloc_len = pool->len;
79	0	pool->entropy = entropy;
80
81	0	return pool;
82	0	}
83
84		/*
85		* Free \|pool\|, securely erasing its buffer.
86		*/
87		void ossl_rand_pool_free(RAND_POOL *pool)
88	48	{
89	48	if (pool == NULL)
90	0	return;
91
92		/*
93		* Although it would be advisable from a cryptographical viewpoint,
94		* we are not allowed to clear attached buffers, since they are passed
95		* to ossl_rand_pool_attach() as `const unsigned char*`.
96		* (see corresponding comment in ossl_rand_pool_attach()).
97		*/
98	48	if (!pool->attached) {
99	48	if (pool->secure)
100	48	OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
101	0	else
102	0	OPENSSL_clear_free(pool->buffer, pool->alloc_len);
103	48	}
104
105	48	OPENSSL_free(pool);
106	48	}
107
108		/*
109		* Return the \|pool\|'s buffer to the caller (readonly).
110		*/
111		const unsigned char ossl_rand_pool_buffer(RAND_POOL pool)
112	0	{
113	0	return pool->buffer;
114	0	}
115
116		/*
117		* Return the \|pool\|'s entropy to the caller.
118		*/
119		size_t ossl_rand_pool_entropy(RAND_POOL *pool)
120	0	{
121	0	return pool->entropy;
122	0	}
123
124		/*
125		* Return the \|pool\|'s buffer length to the caller.
126		*/
127		size_t ossl_rand_pool_length(RAND_POOL *pool)
128	48	{
129	48	return pool->len;
130	48	}
131
132		/*
133		* Detach the \|pool\| buffer and return it to the caller.
134		* It's the responsibility of the caller to free the buffer
135		* using OPENSSL_secure_clear_free() or to re-attach it
136		* again to the pool using ossl_rand_pool_reattach().
137		*/
138		unsigned char ossl_rand_pool_detach(RAND_POOL pool)
139	48	{
140	48	unsigned char *ret = pool->buffer;
141	48	pool->buffer = NULL;
142	48	pool->entropy = 0;
143	48	return ret;
144	48	}
145
146		/*
147		* Re-attach the \|pool\| buffer. It is only allowed to pass
148		* the \|buffer\| which was previously detached from the same pool.
149		*/
150		void ossl_rand_pool_reattach(RAND_POOL pool, unsigned char buffer)
151	0	{
152	0	pool->buffer = buffer;
153	0	OPENSSL_cleanse(pool->buffer, pool->len);
154	0	pool->len = 0;
155	0	}
156
157		/*
158		* If \|entropy_factor\| bits contain 1 bit of entropy, how many bytes does one
159		* need to obtain at least \|bits\| bits of entropy?
160		*/
161		#define ENTROPY_TO_BYTES(bits, entropy_factor) \
162	48	(((bits) * (entropy_factor) + 7) / 8)
163
164
165		/*
166		* Checks whether the \|pool\|'s entropy is available to the caller.
167		* This is the case when entropy count and buffer length are high enough.
168		* Returns
169		*
170		* \|entropy\| if the entropy count and buffer size is large enough
171		* 0 otherwise
172		*/
173		size_t ossl_rand_pool_entropy_available(RAND_POOL *pool)
174	48	{
175	48	if (pool->entropy < pool->entropy_requested)
176	0	return 0;
177
178	48	if (pool->len < pool->min_len)
179	0	return 0;
180
181	48	return pool->entropy;
182	48	}
183
184		/*
185		* Returns the (remaining) amount of entropy needed to fill
186		* the random pool.
187		*/
188
189		size_t ossl_rand_pool_entropy_needed(RAND_POOL *pool)
190	48	{
191	48	if (pool->entropy < pool->entropy_requested)
192	48	return pool->entropy_requested - pool->entropy;
193
194	0	return 0;
195	48	}
196
197		/* Increase the allocation size -- not usable for an attached pool */
198		static int rand_pool_grow(RAND_POOL *pool, size_t len)
199	96	{
200	96	if (len > pool->alloc_len - pool->len) {
201	0	unsigned char *p;
202	0	const size_t limit = pool->max_len / 2;
203	0	size_t newlen = pool->alloc_len;
204
205	0	if (pool->attached \|\| len > pool->max_len - pool->len) {
206	0	ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
207	0	return 0;
208	0	}
209
210	0	do
211	0	newlen = newlen < limit ? newlen * 2 : pool->max_len;
212	0	while (len > newlen - pool->len);
213
214	0	if (pool->secure)
215	0	p = OPENSSL_secure_zalloc(newlen);
216	0	else
217	0	p = OPENSSL_zalloc(newlen);
218	0	if (p == NULL)
219	0	return 0;
220	0	memcpy(p, pool->buffer, pool->len);
221	0	if (pool->secure)
222	0	OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
223	0	else
224	0	OPENSSL_clear_free(pool->buffer, pool->alloc_len);
225	0	pool->buffer = p;
226	0	pool->alloc_len = newlen;
227	0	}
228	96	return 1;
229	96	}
230
231		/*
232		* Returns the number of bytes needed to fill the pool, assuming
233		* the input has 1 / \|entropy_factor\| entropy bits per data bit.
234		* In case of an error, 0 is returned.
235		*/
236
237		size_t ossl_rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
238	48	{
239	48	size_t bytes_needed;
240	48	size_t entropy_needed = ossl_rand_pool_entropy_needed(pool);
241
242	48	if (entropy_factor < 1) {
243	0	ERR_raise(ERR_LIB_RAND, RAND_R_ARGUMENT_OUT_OF_RANGE);
244	0	return 0;
245	0	}
246
247	48	bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
248
249	48	if (bytes_needed > pool->max_len - pool->len) {
250		/* not enough space left */
251	0	ERR_raise_data(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW,
252	0	"entropy_factor=%u, entropy_needed=%zu, bytes_needed=%zu,"
253	0	"pool->max_len=%zu, pool->len=%zu",
254	0	entropy_factor, entropy_needed, bytes_needed,
255	0	pool->max_len, pool->len);
256	0	return 0;
257	0	}
258
259	48	if (pool->len < pool->min_len &&
260	48	bytes_needed < pool->min_len - pool->len)
261		/* to meet the min_len requirement */
262	0	bytes_needed = pool->min_len - pool->len;
263
264		/*
265		* Make sure the buffer is large enough for the requested amount
266		* of data. This guarantees that existing code patterns where
267		* ossl_rand_pool_add_begin, ossl_rand_pool_add_end or ossl_rand_pool_add
268		* are used to collect entropy data without any error handling
269		* whatsoever, continue to be valid.
270		* Furthermore if the allocation here fails once, make sure that
271		* we don't fall back to a less secure or even blocking random source,
272		* as that could happen by the existing code patterns.
273		* This is not a concern for additional data, therefore that
274		* is not needed if rand_pool_grow fails in other places.
275		*/
276	48	if (!rand_pool_grow(pool, bytes_needed)) {
277		/* persistent error for this pool */
278	0	pool->max_len = pool->len = 0;
279	0	return 0;
280	0	}
281
282	48	return bytes_needed;
283	48	}
284
285		/* Returns the remaining number of bytes available */
286		size_t ossl_rand_pool_bytes_remaining(RAND_POOL *pool)
287	0	{
288	0	return pool->max_len - pool->len;
289	0	}
290
291		/*
292		* Add random bytes to the random pool.
293		*
294		* It is expected that the \|buffer\| contains \|len\| bytes of
295		* random input which contains at least \|entropy\| bits of
296		* randomness.
297		*
298		* Returns 1 if the added amount is adequate, otherwise 0
299		*/
300		int ossl_rand_pool_add(RAND_POOL *pool,
301		const unsigned char *buffer, size_t len, size_t entropy)
302	0	{
303	0	if (len > pool->max_len - pool->len) {
304	0	ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG);
305	0	return 0;
306	0	}
307
308	0	if (pool->buffer == NULL) {
309	0	ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
310	0	return 0;
311	0	}
312
313	0	if (len > 0) {
314		/*
315		* This is to protect us from accidentally passing the buffer
316		* returned from ossl_rand_pool_add_begin.
317		* The check for alloc_len makes sure we do not compare the
318		* address of the end of the allocated memory to something
319		* different, since that comparison would have an
320		* indeterminate result.
321		*/
322	0	if (pool->alloc_len > pool->len && pool->buffer + pool->len == buffer) {
323	0	ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
324	0	return 0;
325	0	}
326		/*
327		* We have that only for cases when a pool is used to collect
328		* additional data.
329		* For entropy data, as long as the allocation request stays within
330		* the limits given by ossl_rand_pool_bytes_needed this rand_pool_grow
331		* below is guaranteed to succeed, thus no allocation happens.
332		*/
333	0	if (!rand_pool_grow(pool, len))
334	0	return 0;
335	0	memcpy(pool->buffer + pool->len, buffer, len);
336	0	pool->len += len;
337	0	pool->entropy += entropy;
338	0	}
339
340	0	return 1;
341	0	}
342
343		/*
344		* Start to add random bytes to the random pool in-place.
345		*
346		* Reserves the next \|len\| bytes for adding random bytes in-place
347		* and returns a pointer to the buffer.
348		* The caller is allowed to copy up to \|len\| bytes into the buffer.
349		* If \|len\| == 0 this is considered a no-op and a NULL pointer
350		* is returned without producing an error message.
351		*
352		* After updating the buffer, ossl_rand_pool_add_end() needs to be called
353		* to finish the update operation (see next comment).
354		*/
355		unsigned char ossl_rand_pool_add_begin(RAND_POOL pool, size_t len)
356	48	{
357	48	if (len == 0)
358	0	return NULL;
359
360	48	if (len > pool->max_len - pool->len) {
361	0	ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW);
362	0	return NULL;
363	0	}
364
365	48	if (pool->buffer == NULL) {
366	0	ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
367	0	return NULL;
368	0	}
369
370		/*
371		* As long as the allocation request stays within the limits given
372		* by ossl_rand_pool_bytes_needed this rand_pool_grow below is guaranteed
373		* to succeed, thus no allocation happens.
374		* We have that only for cases when a pool is used to collect
375		* additional data. Then the buffer might need to grow here,
376		* and of course the caller is responsible to check the return
377		* value of this function.
378		*/
379	48	if (!rand_pool_grow(pool, len))
380	0	return NULL;
381
382	48	return pool->buffer + pool->len;
383	48	}
384
385		/*
386		* Finish to add random bytes to the random pool in-place.
387		*
388		* Finishes an in-place update of the random pool started by
389		* ossl_rand_pool_add_begin() (see previous comment).
390		* It is expected that \|len\| bytes of random input have been added
391		* to the buffer which contain at least \|entropy\| bits of randomness.
392		* It is allowed to add less bytes than originally reserved.
393		*/
394		int ossl_rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
395	48	{
396	48	if (len > pool->alloc_len - pool->len) {
397	0	ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW);
398	0	return 0;
399	0	}
400
401	48	if (len > 0) {
402	48	pool->len += len;
403	48	pool->entropy += entropy;
404	48	}
405
406	48	return 1;
407	48	}
408
409		/**
410		* @brief Mix in the additional input into an existing entropy in the pool
411		*
412		* @param pool A RAND_POOL to mix the additional input in
413		* @param adin A buffer with the additional input
414		* @param adin_len A length of the additional input
415		*
416		* @return 1 if there is any existing entropy in the pool so the additional input
417		* can be mixed in, 0 otherwise.
418		*/
419
420		int ossl_rand_pool_adin_mix_in(RAND_POOL pool, const unsigned char adin,
421		size_t adin_len)
422	48	{
423	48	if (adin == NULL \|\| adin_len == 0)
424		/* Nothing to mix in -> success */
425	0	return 1;
426
427	48	if (pool->buffer == NULL) {
428	0	ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
429	0	return 0;
430	0	}
431
432	48	if (pool->len == 0) {
433	0	ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_IS_EMPTY);
434	0	return 0;
435	0	}
436
437	48	if (adin != NULL && adin_len > 0) {
438	48	size_t i;
439
440		/* xor the additional data into the pool */
441	432	for (i = 0; i < adin_len; ++i)
442	384	pool->buffer[i % pool->len] ^= adin[i];
443	48	}
444
445	48	return 1;
446	48	}