1 /* crypto/bn/bn_ctx.c */
2 /* Written by Ulf Moeller for the OpenSSL project. */
3 /* ====================================================================
4 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
18 * 3. All advertising materials mentioning features or use of this
19 * software must display the following acknowledgment:
20 * "This product includes software developed by the OpenSSL Project
21 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
23 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
24 * endorse or promote products derived from this software without
25 * prior written permission. For written permission, please contact
26 * openssl-core@openssl.org.
28 * 5. Products derived from this software may not be called "OpenSSL"
29 * nor may "OpenSSL" appear in their names without prior written
30 * permission of the OpenSSL Project.
32 * 6. Redistributions of any form whatsoever must retain the following
34 * "This product includes software developed by the OpenSSL Project
35 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
37 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
38 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
40 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
43 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
44 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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47 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
48 * OF THE POSSIBILITY OF SUCH DAMAGE.
49 * ====================================================================
51 * This product includes cryptographic software written by Eric Young
52 * (eay@cryptsoft.com). This product includes software written by Tim
53 * Hudson (tjh@cryptsoft.com).
57 #if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
72 * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
73 * check they can be safely removed.
74 * - Check +1 and other ugliness in BN_from_montgomery()
76 * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
77 * appropriate 'block' size that will be honoured by bn_expand_internal() to
78 * prevent piddly little reallocations. OTOH, profiling bignum expansions in
79 * BN_CTX doesn't show this to be a big issue.
82 /* How many bignums are in each "pool item"; */
83 #define BN_CTX_POOL_SIZE 16
84 /* The stack frame info is resizing, set a first-time expansion size; */
85 #define BN_CTX_START_FRAMES 32
91 /* A bundle of bignums that can be linked with other bundles */
92 typedef struct bignum_pool_item
94 /* The bignum values */
95 BIGNUM vals[BN_CTX_POOL_SIZE];
96 /* Linked-list admin */
97 struct bignum_pool_item *prev, *next;
99 /* A linked-list of bignums grouped in bundles */
100 typedef struct bignum_pool
102 /* Linked-list admin */
103 BN_POOL_ITEM *head, *current, *tail;
104 /* Stack depth and allocation size */
107 static void BN_POOL_init(BN_POOL *);
108 static void BN_POOL_finish(BN_POOL *);
109 #ifndef OPENSSL_NO_DEPRECATED
110 static void BN_POOL_reset(BN_POOL *);
112 static BIGNUM * BN_POOL_get(BN_POOL *);
113 static void BN_POOL_release(BN_POOL *, unsigned int);
119 /* A wrapper to manage the "stack frames" */
120 typedef struct bignum_ctx_stack
122 /* Array of indexes into the bignum stack */
123 unsigned int *indexes;
124 /* Number of stack frames, and the size of the allocated array */
125 unsigned int depth, size;
127 static void BN_STACK_init(BN_STACK *);
128 static void BN_STACK_finish(BN_STACK *);
129 #ifndef OPENSSL_NO_DEPRECATED
130 static void BN_STACK_reset(BN_STACK *);
132 static int BN_STACK_push(BN_STACK *, unsigned int);
133 static unsigned int BN_STACK_pop(BN_STACK *);
139 /* The opaque BN_CTX type */
142 /* The bignum bundles */
144 /* The "stack frames", if you will */
146 /* The number of bignums currently assigned */
148 /* Depth of stack overflow */
150 /* Block "gets" until an "end" (compatibility behaviour) */
154 /* Enable this to find BN_CTX bugs */
156 static const char *ctxdbg_cur = NULL;
157 static void ctxdbg(BN_CTX *ctx)
159 unsigned int bnidx = 0, fpidx = 0;
160 BN_POOL_ITEM *item = ctx->pool.head;
161 BN_STACK *stack = &ctx->stack;
162 fprintf(stderr,"(%08x): ", (unsigned int)ctx);
163 while(bnidx < ctx->used)
165 fprintf(stderr,"%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
166 if(!(bnidx % BN_CTX_POOL_SIZE))
169 fprintf(stderr,"\n");
171 fprintf(stderr," : ");
172 while(fpidx < stack->depth)
174 while(bnidx++ < stack->indexes[fpidx])
176 fprintf(stderr,"^^^ ");
180 fprintf(stderr,"\n");
182 #define CTXDBG_ENTRY(str, ctx) do { \
183 ctxdbg_cur = (str); \
184 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
187 #define CTXDBG_EXIT(ctx) do { \
188 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
191 #define CTXDBG_RET(ctx,ret)
193 #define CTXDBG_ENTRY(str, ctx)
194 #define CTXDBG_EXIT(ctx)
195 #define CTXDBG_RET(ctx,ret)
198 /* This function is an evil legacy and should not be used. This implementation
199 * is WYSIWYG, though I've done my best. */
200 #ifndef OPENSSL_NO_DEPRECATED
201 void BN_CTX_init(BN_CTX *ctx)
203 /* Assume the caller obtained the context via BN_CTX_new() and so is
204 * trying to reset it for use. Nothing else makes sense, least of all
205 * binary compatibility from a time when they could declare a static
207 BN_POOL_reset(&ctx->pool);
208 BN_STACK_reset(&ctx->stack);
215 BN_CTX *BN_CTX_new(void)
217 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
220 BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
223 /* Initialise the structure */
224 BN_POOL_init(&ret->pool);
225 BN_STACK_init(&ret->stack);
232 void BN_CTX_free(BN_CTX *ctx)
238 BN_POOL_ITEM *pool = ctx->pool.head;
239 fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
240 ctx->stack.size, ctx->pool.size);
241 fprintf(stderr,"dmaxs: ");
244 while(loop < BN_CTX_POOL_SIZE)
245 fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
248 fprintf(stderr,"\n");
251 BN_STACK_finish(&ctx->stack);
252 BN_POOL_finish(&ctx->pool);
256 void BN_CTX_start(BN_CTX *ctx)
258 CTXDBG_ENTRY("BN_CTX_start", ctx);
259 /* If we're already overflowing ... */
260 if(ctx->err_stack || ctx->too_many)
262 /* (Try to) get a new frame pointer */
263 else if(!BN_STACK_push(&ctx->stack, ctx->used))
265 BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
271 void BN_CTX_end(BN_CTX *ctx)
273 CTXDBG_ENTRY("BN_CTX_end", ctx);
278 unsigned int fp = BN_STACK_pop(&ctx->stack);
279 /* Does this stack frame have anything to release? */
281 BN_POOL_release(&ctx->pool, ctx->used - fp);
283 /* Unjam "too_many" in case "get" had failed */
289 BIGNUM *BN_CTX_get(BN_CTX *ctx)
292 CTXDBG_ENTRY("BN_CTX_get", ctx);
293 if(ctx->err_stack || ctx->too_many) return NULL;
294 if((ret = BN_POOL_get(&ctx->pool)) == NULL)
296 /* Setting too_many prevents repeated "get" attempts from
297 * cluttering the error stack. */
299 BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
302 /* OK, make sure the returned bignum is "zero" */
305 CTXDBG_RET(ctx, ret);
313 static void BN_STACK_init(BN_STACK *st)
316 st->depth = st->size = 0;
319 static void BN_STACK_finish(BN_STACK *st)
321 if(st->size) OPENSSL_free(st->indexes);
324 #ifndef OPENSSL_NO_DEPRECATED
325 static void BN_STACK_reset(BN_STACK *st)
331 static int BN_STACK_push(BN_STACK *st, unsigned int idx)
333 if(st->depth == st->size)
336 unsigned int newsize = (st->size ?
337 (st->size * 3 / 2) : BN_CTX_START_FRAMES);
338 unsigned int *newitems = OPENSSL_malloc(newsize *
339 sizeof(unsigned int));
340 if(!newitems) return 0;
342 memcpy(newitems, st->indexes, st->depth *
343 sizeof(unsigned int));
344 if(st->size) OPENSSL_free(st->indexes);
345 st->indexes = newitems;
348 st->indexes[(st->depth)++] = idx;
352 static unsigned int BN_STACK_pop(BN_STACK *st)
354 return st->indexes[--(st->depth)];
361 static void BN_POOL_init(BN_POOL *p)
363 p->head = p->current = p->tail = NULL;
364 p->used = p->size = 0;
367 static void BN_POOL_finish(BN_POOL *p)
371 unsigned int loop = 0;
372 BIGNUM *bn = p->head->vals;
373 while(loop++ < BN_CTX_POOL_SIZE)
375 if(bn->d) BN_clear_free(bn);
378 p->current = p->head->next;
379 OPENSSL_free(p->head);
380 p->head = p->current;
384 #ifndef OPENSSL_NO_DEPRECATED
385 static void BN_POOL_reset(BN_POOL *p)
387 BN_POOL_ITEM *item = p->head;
390 unsigned int loop = 0;
391 BIGNUM *bn = item->vals;
392 while(loop++ < BN_CTX_POOL_SIZE)
394 if(bn->d) BN_clear(bn);
399 p->current = p->head;
404 static BIGNUM *BN_POOL_get(BN_POOL *p)
406 if(p->used == p->size)
409 unsigned int loop = 0;
410 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
411 if(!item) return NULL;
412 /* Initialise the structure */
414 while(loop++ < BN_CTX_POOL_SIZE)
416 item->prev = p->tail;
420 p->head = p->current = p->tail = item;
423 p->tail->next = item;
427 p->size += BN_CTX_POOL_SIZE;
429 /* Return the first bignum from the new pool */
433 p->current = p->head;
434 else if((p->used % BN_CTX_POOL_SIZE) == 0)
435 p->current = p->current->next;
436 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
439 static void BN_POOL_release(BN_POOL *p, unsigned int num)
441 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
445 bn_check_top(p->current->vals + offset);
448 offset = BN_CTX_POOL_SIZE - 1;
449 p->current = p->current->prev;