sl@0: /* crypto/bn/bn_ctx.c */
sl@0: /* Written by Ulf Moeller for the OpenSSL project. */
sl@0: /* ====================================================================
sl@0:  * Copyright (c) 1998-2004 The OpenSSL Project.  All rights reserved.
sl@0:  *
sl@0:  * Redistribution and use in source and binary forms, with or without
sl@0:  * modification, are permitted provided that the following conditions
sl@0:  * are met:
sl@0:  *
sl@0:  * 1. Redistributions of source code must retain the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer. 
sl@0:  *
sl@0:  * 2. Redistributions in binary form must reproduce the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer in
sl@0:  *    the documentation and/or other materials provided with the
sl@0:  *    distribution.
sl@0:  *
sl@0:  * 3. All advertising materials mentioning features or use of this
sl@0:  *    software must display the following acknowledgment:
sl@0:  *    "This product includes software developed by the OpenSSL Project
sl@0:  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
sl@0:  *
sl@0:  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
sl@0:  *    endorse or promote products derived from this software without
sl@0:  *    prior written permission. For written permission, please contact
sl@0:  *    openssl-core@openssl.org.
sl@0:  *
sl@0:  * 5. Products derived from this software may not be called "OpenSSL"
sl@0:  *    nor may "OpenSSL" appear in their names without prior written
sl@0:  *    permission of the OpenSSL Project.
sl@0:  *
sl@0:  * 6. Redistributions of any form whatsoever must retain the following
sl@0:  *    acknowledgment:
sl@0:  *    "This product includes software developed by the OpenSSL Project
sl@0:  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
sl@0:  *
sl@0:  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
sl@0:  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
sl@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
sl@0:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
sl@0:  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
sl@0:  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
sl@0:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
sl@0:  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
sl@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
sl@0:  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
sl@0:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
sl@0:  * OF THE POSSIBILITY OF SUCH DAMAGE.
sl@0:  * ====================================================================
sl@0:  *
sl@0:  * This product includes cryptographic software written by Eric Young
sl@0:  * (eay@cryptsoft.com).  This product includes software written by Tim
sl@0:  * Hudson (tjh@cryptsoft.com).
sl@0:  *
sl@0:  */
sl@0: 
sl@0: #if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
sl@0: #ifndef NDEBUG
sl@0: #define NDEBUG
sl@0: #endif
sl@0: #endif
sl@0: 
sl@0: #include <stdio.h>
sl@0: #include <assert.h>
sl@0: 
sl@0: #include "cryptlib.h"
sl@0: #include "bn_lcl.h"
sl@0: 
sl@0: /* TODO list
sl@0:  *
sl@0:  * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
sl@0:  * check they can be safely removed.
sl@0:  *  - Check +1 and other ugliness in BN_from_montgomery()
sl@0:  *
sl@0:  * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
sl@0:  * appropriate 'block' size that will be honoured by bn_expand_internal() to
sl@0:  * prevent piddly little reallocations. OTOH, profiling bignum expansions in
sl@0:  * BN_CTX doesn't show this to be a big issue.
sl@0:  */
sl@0: 
sl@0: /* How many bignums are in each "pool item"; */
sl@0: #define BN_CTX_POOL_SIZE	16
sl@0: /* The stack frame info is resizing, set a first-time expansion size; */
sl@0: #define BN_CTX_START_FRAMES	32
sl@0: 
sl@0: /***********/
sl@0: /* BN_POOL */
sl@0: /***********/
sl@0: 
sl@0: /* A bundle of bignums that can be linked with other bundles */
sl@0: typedef struct bignum_pool_item
sl@0: 	{
sl@0: 	/* The bignum values */
sl@0: 	BIGNUM vals[BN_CTX_POOL_SIZE];
sl@0: 	/* Linked-list admin */
sl@0: 	struct bignum_pool_item *prev, *next;
sl@0: 	} BN_POOL_ITEM;
sl@0: /* A linked-list of bignums grouped in bundles */
sl@0: typedef struct bignum_pool
sl@0: 	{
sl@0: 	/* Linked-list admin */
sl@0: 	BN_POOL_ITEM *head, *current, *tail;
sl@0: 	/* Stack depth and allocation size */
sl@0: 	unsigned used, size;
sl@0: 	} BN_POOL;
sl@0: static void		BN_POOL_init(BN_POOL *);
sl@0: static void		BN_POOL_finish(BN_POOL *);
sl@0: #ifndef OPENSSL_NO_DEPRECATED
sl@0: static void		BN_POOL_reset(BN_POOL *);
sl@0: #endif
sl@0: static BIGNUM *		BN_POOL_get(BN_POOL *);
sl@0: static void		BN_POOL_release(BN_POOL *, unsigned int);
sl@0: 
sl@0: /************/
sl@0: /* BN_STACK */
sl@0: /************/
sl@0: 
sl@0: /* A wrapper to manage the "stack frames" */
sl@0: typedef struct bignum_ctx_stack
sl@0: 	{
sl@0: 	/* Array of indexes into the bignum stack */
sl@0: 	unsigned int *indexes;
sl@0: 	/* Number of stack frames, and the size of the allocated array */
sl@0: 	unsigned int depth, size;
sl@0: 	} BN_STACK;
sl@0: static void		BN_STACK_init(BN_STACK *);
sl@0: static void		BN_STACK_finish(BN_STACK *);
sl@0: #ifndef OPENSSL_NO_DEPRECATED
sl@0: static void		BN_STACK_reset(BN_STACK *);
sl@0: #endif
sl@0: static int		BN_STACK_push(BN_STACK *, unsigned int);
sl@0: static unsigned int	BN_STACK_pop(BN_STACK *);
sl@0: 
sl@0: /**********/
sl@0: /* BN_CTX */
sl@0: /**********/
sl@0: 
sl@0: /* The opaque BN_CTX type */
sl@0: struct bignum_ctx
sl@0: 	{
sl@0: 	/* The bignum bundles */
sl@0: 	BN_POOL pool;
sl@0: 	/* The "stack frames", if you will */
sl@0: 	BN_STACK stack;
sl@0: 	/* The number of bignums currently assigned */
sl@0: 	unsigned int used;
sl@0: 	/* Depth of stack overflow */
sl@0: 	int err_stack;
sl@0: 	/* Block "gets" until an "end" (compatibility behaviour) */
sl@0: 	int too_many;
sl@0: 	};
sl@0: 
sl@0: /* Enable this to find BN_CTX bugs */
sl@0: #ifdef BN_CTX_DEBUG
sl@0: static const char *ctxdbg_cur = NULL;
sl@0: static void ctxdbg(BN_CTX *ctx)
sl@0: 	{
sl@0: 	unsigned int bnidx = 0, fpidx = 0;
sl@0: 	BN_POOL_ITEM *item = ctx->pool.head;
sl@0: 	BN_STACK *stack = &ctx->stack;
sl@0: 	fprintf(stderr,"(%08x): ", (unsigned int)ctx);
sl@0: 	while(bnidx < ctx->used)
sl@0: 		{
sl@0: 		fprintf(stderr,"%02x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
sl@0: 		if(!(bnidx % BN_CTX_POOL_SIZE))
sl@0: 			item = item->next;
sl@0: 		}
sl@0: 	fprintf(stderr,"\n");
sl@0: 	bnidx = 0;
sl@0: 	fprintf(stderr,"          : ");
sl@0: 	while(fpidx < stack->depth)
sl@0: 		{
sl@0: 		while(bnidx++ < stack->indexes[fpidx])
sl@0: 			fprintf(stderr,"   ");
sl@0: 		fprintf(stderr,"^^ ");
sl@0: 		bnidx++;
sl@0: 		fpidx++;
sl@0: 		}
sl@0: 	fprintf(stderr,"\n");
sl@0: 	}
sl@0: #define CTXDBG_ENTRY(str, ctx)	do { \
sl@0: 				ctxdbg_cur = (str); \
sl@0: 				fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
sl@0: 				ctxdbg(ctx); \
sl@0: 				} while(0)
sl@0: #define CTXDBG_EXIT(ctx)	do { \
sl@0: 				fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
sl@0: 				ctxdbg(ctx); \
sl@0: 				} while(0)
sl@0: #define CTXDBG_RET(ctx,ret)
sl@0: #else
sl@0: #define CTXDBG_ENTRY(str, ctx)
sl@0: #define CTXDBG_EXIT(ctx)
sl@0: #define CTXDBG_RET(ctx,ret)
sl@0: #endif
sl@0: 
sl@0: /* This function is an evil legacy and should not be used. This implementation
sl@0:  * is WYSIWYG, though I've done my best. */
sl@0: #ifndef OPENSSL_NO_DEPRECATED
sl@0: EXPORT_C void BN_CTX_init(BN_CTX *ctx)
sl@0: 	{
sl@0: 	/* Assume the caller obtained the context via BN_CTX_new() and so is
sl@0: 	 * trying to reset it for use. Nothing else makes sense, least of all
sl@0: 	 * binary compatibility from a time when they could declare a static
sl@0: 	 * variable. */
sl@0: 	BN_POOL_reset(&ctx->pool);
sl@0: 	BN_STACK_reset(&ctx->stack);
sl@0: 	ctx->used = 0;
sl@0: 	ctx->err_stack = 0;
sl@0: 	ctx->too_many = 0;
sl@0: 	}
sl@0: #endif
sl@0: 
sl@0: EXPORT_C BN_CTX *BN_CTX_new(void)
sl@0: 	{
sl@0: 	BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
sl@0: 	if(!ret)
sl@0: 		{
sl@0: 		BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
sl@0: 		return NULL;
sl@0: 		}
sl@0: 	/* Initialise the structure */
sl@0: 	BN_POOL_init(&ret->pool);
sl@0: 	BN_STACK_init(&ret->stack);
sl@0: 	ret->used = 0;
sl@0: 	ret->err_stack = 0;
sl@0: 	ret->too_many = 0;
sl@0: 	return ret;
sl@0: 	}
sl@0: 
sl@0: EXPORT_C void BN_CTX_free(BN_CTX *ctx)
sl@0: 	{
sl@0: 	if (ctx == NULL)
sl@0: 		return;
sl@0: #ifdef BN_CTX_DEBUG
sl@0: 	{
sl@0: 	BN_POOL_ITEM *pool = ctx->pool.head;
sl@0: 	fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
sl@0: 		ctx->stack.size, ctx->pool.size);
sl@0: 	fprintf(stderr,"dmaxs: ");
sl@0: 	while(pool) {
sl@0: 		unsigned loop = 0;
sl@0: 		while(loop < BN_CTX_POOL_SIZE)
sl@0: 			fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
sl@0: 		pool = pool->next;
sl@0: 	}
sl@0: 	fprintf(stderr,"\n");
sl@0: 	}
sl@0: #endif
sl@0: 	BN_STACK_finish(&ctx->stack);
sl@0: 	BN_POOL_finish(&ctx->pool);
sl@0: 	OPENSSL_free(ctx);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C void BN_CTX_start(BN_CTX *ctx)
sl@0: 	{
sl@0: 	CTXDBG_ENTRY("BN_CTX_start", ctx);
sl@0: 	/* If we're already overflowing ... */
sl@0: 	if(ctx->err_stack || ctx->too_many)
sl@0: 		ctx->err_stack++;
sl@0: 	/* (Try to) get a new frame pointer */
sl@0: 	else if(!BN_STACK_push(&ctx->stack, ctx->used))
sl@0: 		{
sl@0: 		BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
sl@0: 		ctx->err_stack++;
sl@0: 		}
sl@0: 	CTXDBG_EXIT(ctx);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C void BN_CTX_end(BN_CTX *ctx)
sl@0: 	{
sl@0: 	CTXDBG_ENTRY("BN_CTX_end", ctx);
sl@0: 	if(ctx->err_stack)
sl@0: 		ctx->err_stack--;
sl@0: 	else
sl@0: 		{
sl@0: 		unsigned int fp = BN_STACK_pop(&ctx->stack);
sl@0: 		/* Does this stack frame have anything to release? */
sl@0: 		if(fp < ctx->used)
sl@0: 			BN_POOL_release(&ctx->pool, ctx->used - fp);
sl@0: 		ctx->used = fp;
sl@0: 		/* Unjam "too_many" in case "get" had failed */
sl@0: 		ctx->too_many = 0;
sl@0: 		}
sl@0: 	CTXDBG_EXIT(ctx);
sl@0: 	}
sl@0: 
sl@0: EXPORT_C BIGNUM *BN_CTX_get(BN_CTX *ctx)
sl@0: 	{
sl@0: 	BIGNUM *ret;
sl@0: 	CTXDBG_ENTRY("BN_CTX_get", ctx);
sl@0: 	if(ctx->err_stack || ctx->too_many) return NULL;
sl@0: 	if((ret = BN_POOL_get(&ctx->pool)) == NULL)
sl@0: 		{
sl@0: 		/* Setting too_many prevents repeated "get" attempts from
sl@0: 		 * cluttering the error stack. */
sl@0: 		ctx->too_many = 1;
sl@0: 		BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
sl@0: 		return NULL;
sl@0: 		}
sl@0: 	/* OK, make sure the returned bignum is "zero" */
sl@0: 	BN_zero(ret);
sl@0: 	ctx->used++;
sl@0: 	CTXDBG_RET(ctx, ret);
sl@0: 	return ret;
sl@0: 	}
sl@0: 
sl@0: /************/
sl@0: /* BN_STACK */
sl@0: /************/
sl@0: 
sl@0: static void BN_STACK_init(BN_STACK *st)
sl@0: 	{
sl@0: 	st->indexes = NULL;
sl@0: 	st->depth = st->size = 0;
sl@0: 	}
sl@0: 
sl@0: static void BN_STACK_finish(BN_STACK *st)
sl@0: 	{
sl@0: 	if(st->size) OPENSSL_free(st->indexes);
sl@0: 	}
sl@0: 
sl@0: #ifndef OPENSSL_NO_DEPRECATED
sl@0: static void BN_STACK_reset(BN_STACK *st)
sl@0: 	{
sl@0: 	st->depth = 0;
sl@0: 	}
sl@0: #endif
sl@0: 
sl@0: static int BN_STACK_push(BN_STACK *st, unsigned int idx)
sl@0: 	{
sl@0: 	if(st->depth == st->size)
sl@0: 		/* Need to expand */
sl@0: 		{
sl@0: 		unsigned int newsize = (st->size ?
sl@0: 				(st->size * 3 / 2) : BN_CTX_START_FRAMES);
sl@0: 		unsigned int *newitems = OPENSSL_malloc(newsize *
sl@0: 						sizeof(unsigned int));
sl@0: 		if(!newitems) return 0;
sl@0: 		if(st->depth)
sl@0: 			memcpy(newitems, st->indexes, st->depth *
sl@0: 						sizeof(unsigned int));
sl@0: 		if(st->size) OPENSSL_free(st->indexes);
sl@0: 		st->indexes = newitems;
sl@0: 		st->size = newsize;
sl@0: 		}
sl@0: 	st->indexes[(st->depth)++] = idx;
sl@0: 	return 1;
sl@0: 	}
sl@0: 
sl@0: static unsigned int BN_STACK_pop(BN_STACK *st)
sl@0: 	{
sl@0: 	return st->indexes[--(st->depth)];
sl@0: 	}
sl@0: 
sl@0: /***********/
sl@0: /* BN_POOL */
sl@0: /***********/
sl@0: 
sl@0: static void BN_POOL_init(BN_POOL *p)
sl@0: 	{
sl@0: 	p->head = p->current = p->tail = NULL;
sl@0: 	p->used = p->size = 0;
sl@0: 	}
sl@0: 
sl@0: static void BN_POOL_finish(BN_POOL *p)
sl@0: 	{
sl@0: 	while(p->head)
sl@0: 		{
sl@0: 		unsigned int loop = 0;
sl@0: 		BIGNUM *bn = p->head->vals;
sl@0: 		while(loop++ < BN_CTX_POOL_SIZE)
sl@0: 			{
sl@0: 			if(bn->d) BN_clear_free(bn);
sl@0: 			bn++;
sl@0: 			}
sl@0: 		p->current = p->head->next;
sl@0: 		OPENSSL_free(p->head);
sl@0: 		p->head = p->current;
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: #ifndef OPENSSL_NO_DEPRECATED
sl@0: static void BN_POOL_reset(BN_POOL *p)
sl@0: 	{
sl@0: 	BN_POOL_ITEM *item = p->head;
sl@0: 	while(item)
sl@0: 		{
sl@0: 		unsigned int loop = 0;
sl@0: 		BIGNUM *bn = item->vals;
sl@0: 		while(loop++ < BN_CTX_POOL_SIZE)
sl@0: 			{
sl@0: 			if(bn->d) BN_clear(bn);
sl@0: 			bn++;
sl@0: 			}
sl@0: 		item = item->next;
sl@0: 		}
sl@0: 	p->current = p->head;
sl@0: 	p->used = 0;
sl@0: 	}
sl@0: #endif
sl@0: 
sl@0: static BIGNUM *BN_POOL_get(BN_POOL *p)
sl@0: 	{
sl@0: 	if(p->used == p->size)
sl@0: 		{
sl@0: 		BIGNUM *bn;
sl@0: 		unsigned int loop = 0;
sl@0: 		BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
sl@0: 		if(!item) return NULL;
sl@0: 		/* Initialise the structure */
sl@0: 		bn = item->vals;
sl@0: 		while(loop++ < BN_CTX_POOL_SIZE)
sl@0: 			BN_init(bn++);
sl@0: 		item->prev = p->tail;
sl@0: 		item->next = NULL;
sl@0: 		/* Link it in */
sl@0: 		if(!p->head)
sl@0: 			p->head = p->current = p->tail = item;
sl@0: 		else
sl@0: 			{
sl@0: 			p->tail->next = item;
sl@0: 			p->tail = item;
sl@0: 			p->current = item;
sl@0: 			}
sl@0: 		p->size += BN_CTX_POOL_SIZE;
sl@0: 		p->used++;
sl@0: 		/* Return the first bignum from the new pool */
sl@0: 		return item->vals;
sl@0: 		}
sl@0: 	if(!p->used)
sl@0: 		p->current = p->head;
sl@0: 	else if((p->used % BN_CTX_POOL_SIZE) == 0)
sl@0: 		p->current = p->current->next;
sl@0: 	return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
sl@0: 	}
sl@0: 
sl@0: static void BN_POOL_release(BN_POOL *p, unsigned int num)
sl@0: 	{
sl@0: 	unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
sl@0: 	p->used -= num;
sl@0: 	while(num--)
sl@0: 		{
sl@0: 		bn_check_top(p->current->vals + offset);
sl@0: 		if(!offset)
sl@0: 			{
sl@0: 			offset = BN_CTX_POOL_SIZE - 1;
sl@0: 			p->current = p->current->prev;
sl@0: 			}
sl@0: 		else
sl@0: 			offset--;
sl@0: 		}
sl@0: 	}
sl@0: