/* Written by Ulf Moeller for the OpenSSL project. */
/* ====================================================================
* Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/bn.h>
#include <string.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "../../internal.h"
// How many bignums are in each "pool item";
#define BN_CTX_POOL_SIZE 16
// The stack frame info is resizing, set a first-time expansion size;
#define BN_CTX_START_FRAMES 32
// A bundle of bignums that can be linked with other bundles
typedef struct bignum_pool_item {
// The bignum values
BIGNUM vals[BN_CTX_POOL_SIZE];
// Linked-list admin
struct bignum_pool_item *prev, *next;
} BN_POOL_ITEM;
typedef struct bignum_pool {
// Linked-list admin
BN_POOL_ITEM *head, *current, *tail;
// Stack depth and allocation size
unsigned used, size;
} BN_POOL;
static void BN_POOL_init(BN_POOL *);
static void BN_POOL_finish(BN_POOL *);
static BIGNUM *BN_POOL_get(BN_POOL *);
static void BN_POOL_release(BN_POOL *, unsigned int);
// BN_STACK
// A wrapper to manage the "stack frames"
typedef struct bignum_ctx_stack {
// Array of indexes into the bignum stack
unsigned int *indexes;
// Number of stack frames, and the size of the allocated array
unsigned int depth, size;
} BN_STACK;
static void BN_STACK_init(BN_STACK *);
static void BN_STACK_finish(BN_STACK *);
static int BN_STACK_push(BN_STACK *, unsigned int);
static unsigned int BN_STACK_pop(BN_STACK *);
// BN_CTX
// The opaque BN_CTX type
struct bignum_ctx {
// The bignum bundles
BN_POOL pool;
// The "stack frames", if you will
BN_STACK stack;
// The number of bignums currently assigned
unsigned int used;
// Depth of stack overflow
int err_stack;
// Block "gets" until an "end" (compatibility behaviour)
int too_many;
};
BN_CTX *BN_CTX_new(void) {
BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
if (!ret) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return NULL;
}
// Initialise the structure
BN_POOL_init(&ret->pool);
BN_STACK_init(&ret->stack);
ret->used = 0;
ret->err_stack = 0;
ret->too_many = 0;
return ret;
}
void BN_CTX_free(BN_CTX *ctx) {
if (ctx == NULL) {
return;
}
BN_STACK_finish(&ctx->stack);
BN_POOL_finish(&ctx->pool);
OPENSSL_free(ctx);
}
void BN_CTX_start(BN_CTX *ctx) {
// If we're already overflowing ...
if (ctx->err_stack || ctx->too_many) {
ctx->err_stack++;
} else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
// (Try to) get a new frame pointer
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
ctx->err_stack++;
}
}
BIGNUM *BN_CTX_get(BN_CTX *ctx) {
BIGNUM *ret;
if (ctx->err_stack || ctx->too_many) {
return NULL;
}
ret = BN_POOL_get(&ctx->pool);
if (ret == NULL) {
// Setting too_many prevents repeated "get" attempts from
// cluttering the error stack.
ctx->too_many = 1;
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
return NULL;
}
// OK, make sure the returned bignum is "zero"
BN_zero(ret);
ctx->used++;
return ret;
}
void BN_CTX_end(BN_CTX *ctx) {
if (ctx->err_stack) {
ctx->err_stack--;
} else {
unsigned int fp = BN_STACK_pop(&ctx->stack);
// Does this stack frame have anything to release?
if (fp < ctx->used) {
BN_POOL_release(&ctx->pool, ctx->used - fp);
}
ctx->used = fp;
// Unjam "too_many" in case "get" had failed
ctx->too_many = 0;
}
}
// BN_STACK
static void BN_STACK_init(BN_STACK *st) {
st->indexes = NULL;
st->depth = st->size = 0;
}
static void BN_STACK_finish(BN_STACK *st) {
OPENSSL_free(st->indexes);
}
static int BN_STACK_push(BN_STACK *st, unsigned int idx) {
if (st->depth == st->size) {
// Need to expand
unsigned int newsize =
(st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES);
unsigned int *newitems = OPENSSL_malloc(newsize * sizeof(unsigned int));
if (!newitems) {
return 0;
}
if (st->depth) {
OPENSSL_memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int));
}
OPENSSL_free(st->indexes);
st->indexes = newitems;
st->size = newsize;
}
st->indexes[(st->depth)++] = idx;
return 1;
}
static unsigned int BN_STACK_pop(BN_STACK *st) {
return st->indexes[--(st->depth)];
}
static void BN_POOL_init(BN_POOL *p) {
p->head = p->current = p->tail = NULL;
p->used = p->size = 0;
}
static void BN_POOL_finish(BN_POOL *p) {
while (p->head) {
for (size_t i = 0; i < BN_CTX_POOL_SIZE; i++) {
BN_clear_free(&p->head->vals[i]);
}
p->current = p->head->next;
OPENSSL_free(p->head);
p->head = p->current;
}
}
static BIGNUM *BN_POOL_get(BN_POOL *p) {
if (p->used == p->size) {
BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
if (!item) {
return NULL;
}
// Initialise the structure
for (size_t i = 0; i < BN_CTX_POOL_SIZE; i++) {
BN_init(&item->vals[i]);
}
item->prev = p->tail;
item->next = NULL;
// Link it in
if (!p->head) {
p->head = p->current = p->tail = item;
} else {
p->tail->next = item;
p->tail = item;
p->current = item;
}
p->size += BN_CTX_POOL_SIZE;
p->used++;
// Return the first bignum from the new pool
return item->vals;
}
if (!p->used) {
p->current = p->head;
} else if ((p->used % BN_CTX_POOL_SIZE) == 0) {
p->current = p->current->next;
}
return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
}
static void BN_POOL_release(BN_POOL *p, unsigned int num) {
unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
p->used -= num;
while (num--) {
if (!offset) {
offset = BN_CTX_POOL_SIZE - 1;
p->current = p->current->prev;
} else {
offset--;
}
}
}