ref: e14d6249749a1101abdad7998e1cd5cdc49e137a
dir: /sys/src/ape/lib/openssl/crypto/bn/bn_ctx.c/
/* crypto/bn/bn_ctx.c */
/* 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).
*
*/
#if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
#ifndef NDEBUG
#define NDEBUG
#endif
#endif
#include <stdio.h>
#include <assert.h>
#include "cryptlib.h"
#include "bn_lcl.h"
/* TODO list
*
* 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
* check they can be safely removed.
* - Check +1 and other ugliness in BN_from_montgomery()
*
* 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
* appropriate 'block' size that will be honoured by bn_expand_internal() to
* prevent piddly little reallocations. OTOH, profiling bignum expansions in
* BN_CTX doesn't show this to be a big issue.
*/
/* 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
/***********/
/* BN_POOL */
/***********/
/* 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;
/* A linked-list of bignums grouped in bundles */
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 *);
#ifndef OPENSSL_NO_DEPRECATED
static void BN_POOL_reset(BN_POOL *);
#endif
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 *);
#ifndef OPENSSL_NO_DEPRECATED
static void BN_STACK_reset(BN_STACK *);
#endif
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;
};
/* Enable this to find BN_CTX bugs */
#ifdef BN_CTX_DEBUG
static const char *ctxdbg_cur = NULL;
static void ctxdbg(BN_CTX *ctx)
{
unsigned int bnidx = 0, fpidx = 0;
BN_POOL_ITEM *item = ctx->pool.head;
BN_STACK *stack = &ctx->stack;
fprintf(stderr,"(%08x): ", (unsigned int)ctx);
while(bnidx < ctx->used)
{
fprintf(stderr,"%02x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
if(!(bnidx % BN_CTX_POOL_SIZE))
item = item->next;
}
fprintf(stderr,"\n");
bnidx = 0;
fprintf(stderr," : ");
while(fpidx < stack->depth)
{
while(bnidx++ < stack->indexes[fpidx])
fprintf(stderr," ");
fprintf(stderr,"^^ ");
bnidx++;
fpidx++;
}
fprintf(stderr,"\n");
}
#define CTXDBG_ENTRY(str, ctx) do { \
ctxdbg_cur = (str); \
fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
ctxdbg(ctx); \
} while(0)
#define CTXDBG_EXIT(ctx) do { \
fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
ctxdbg(ctx); \
} while(0)
#define CTXDBG_RET(ctx,ret)
#else
#define CTXDBG_ENTRY(str, ctx)
#define CTXDBG_EXIT(ctx)
#define CTXDBG_RET(ctx,ret)
#endif
/* This function is an evil legacy and should not be used. This implementation
* is WYSIWYG, though I've done my best. */
#ifndef OPENSSL_NO_DEPRECATED
void BN_CTX_init(BN_CTX *ctx)
{
/* Assume the caller obtained the context via BN_CTX_new() and so is
* trying to reset it for use. Nothing else makes sense, least of all
* binary compatibility from a time when they could declare a static
* variable. */
BN_POOL_reset(&ctx->pool);
BN_STACK_reset(&ctx->stack);
ctx->used = 0;
ctx->err_stack = 0;
ctx->too_many = 0;
}
#endif
BN_CTX *BN_CTX_new(void)
{
BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
if(!ret)
{
BNerr(BN_F_BN_CTX_NEW,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;
#ifdef BN_CTX_DEBUG
{
BN_POOL_ITEM *pool = ctx->pool.head;
fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
ctx->stack.size, ctx->pool.size);
fprintf(stderr,"dmaxs: ");
while(pool) {
unsigned loop = 0;
while(loop < BN_CTX_POOL_SIZE)
fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
pool = pool->next;
}
fprintf(stderr,"\n");
}
#endif
BN_STACK_finish(&ctx->stack);
BN_POOL_finish(&ctx->pool);
OPENSSL_free(ctx);
}
void BN_CTX_start(BN_CTX *ctx)
{
CTXDBG_ENTRY("BN_CTX_start", ctx);
/* If we're already overflowing ... */
if(ctx->err_stack || ctx->too_many)
ctx->err_stack++;
/* (Try to) get a new frame pointer */
else if(!BN_STACK_push(&ctx->stack, ctx->used))
{
BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
ctx->err_stack++;
}
CTXDBG_EXIT(ctx);
}
void BN_CTX_end(BN_CTX *ctx)
{
CTXDBG_ENTRY("BN_CTX_end", 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;
}
CTXDBG_EXIT(ctx);
}
BIGNUM *BN_CTX_get(BN_CTX *ctx)
{
BIGNUM *ret;
CTXDBG_ENTRY("BN_CTX_get", ctx);
if(ctx->err_stack || ctx->too_many) return NULL;
if((ret = BN_POOL_get(&ctx->pool)) == NULL)
{
/* Setting too_many prevents repeated "get" attempts from
* cluttering the error stack. */
ctx->too_many = 1;
BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
return NULL;
}
/* OK, make sure the returned bignum is "zero" */
BN_zero(ret);
ctx->used++;
CTXDBG_RET(ctx, ret);
return ret;
}
/************/
/* 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)
{
if(st->size) OPENSSL_free(st->indexes);
}
#ifndef OPENSSL_NO_DEPRECATED
static void BN_STACK_reset(BN_STACK *st)
{
st->depth = 0;
}
#endif
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)
memcpy(newitems, st->indexes, st->depth *
sizeof(unsigned int));
if(st->size) 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)];
}
/***********/
/* BN_POOL */
/***********/
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)
{
unsigned int loop = 0;
BIGNUM *bn = p->head->vals;
while(loop++ < BN_CTX_POOL_SIZE)
{
if(bn->d) BN_clear_free(bn);
bn++;
}
p->current = p->head->next;
OPENSSL_free(p->head);
p->head = p->current;
}
}
#ifndef OPENSSL_NO_DEPRECATED
static void BN_POOL_reset(BN_POOL *p)
{
BN_POOL_ITEM *item = p->head;
while(item)
{
unsigned int loop = 0;
BIGNUM *bn = item->vals;
while(loop++ < BN_CTX_POOL_SIZE)
{
if(bn->d) BN_clear(bn);
bn++;
}
item = item->next;
}
p->current = p->head;
p->used = 0;
}
#endif
static BIGNUM *BN_POOL_get(BN_POOL *p)
{
if(p->used == p->size)
{
BIGNUM *bn;
unsigned int loop = 0;
BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
if(!item) return NULL;
/* Initialise the structure */
bn = item->vals;
while(loop++ < BN_CTX_POOL_SIZE)
BN_init(bn++);
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--)
{
bn_check_top(p->current->vals + offset);
if(!offset)
{
offset = BN_CTX_POOL_SIZE - 1;
p->current = p->current->prev;
}
else
offset--;
}
}