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)
45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
46 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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)
63 #define OPENSSL_FIPSAPI
73 * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
74 * check they can be safely removed.
75 * - Check +1 and other ugliness in BN_from_montgomery()
77 * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
78 * appropriate 'block' size that will be honoured by bn_expand_internal() to
79 * prevent piddly little reallocations. OTOH, profiling bignum expansions in
80 * BN_CTX doesn't show this to be a big issue.
83 /* How many bignums are in each "pool item"; */
84 #define BN_CTX_POOL_SIZE 16
85 /* The stack frame info is resizing, set a first-time expansion size; */
86 #define BN_CTX_START_FRAMES 32
92 /* A bundle of bignums that can be linked with other bundles */
93 typedef struct bignum_pool_item
95 /* The bignum values */
96 BIGNUM vals[BN_CTX_POOL_SIZE];
97 /* Linked-list admin */
98 struct bignum_pool_item *prev, *next;
100 /* A linked-list of bignums grouped in bundles */
101 typedef struct bignum_pool
103 /* Linked-list admin */
104 BN_POOL_ITEM *head, *current, *tail;
105 /* Stack depth and allocation size */
108 static void BN_POOL_init(BN_POOL *);
109 static void BN_POOL_finish(BN_POOL *);
110 #ifndef OPENSSL_NO_DEPRECATED
111 static void BN_POOL_reset(BN_POOL *);
113 static BIGNUM * BN_POOL_get(BN_POOL *);
114 static void BN_POOL_release(BN_POOL *, unsigned int);
120 /* A wrapper to manage the "stack frames" */
121 typedef struct bignum_ctx_stack
123 /* Array of indexes into the bignum stack */
124 unsigned int *indexes;
125 /* Number of stack frames, and the size of the allocated array */
126 unsigned int depth, size;
128 static void BN_STACK_init(BN_STACK *);
129 static void BN_STACK_finish(BN_STACK *);
130 #ifndef OPENSSL_NO_DEPRECATED
131 static void BN_STACK_reset(BN_STACK *);
133 static int BN_STACK_push(BN_STACK *, unsigned int);
134 static unsigned int BN_STACK_pop(BN_STACK *);
140 /* The opaque BN_CTX type */
143 /* The bignum bundles */
145 /* The "stack frames", if you will */
147 /* The number of bignums currently assigned */
149 /* Depth of stack overflow */
151 /* Block "gets" until an "end" (compatibility behaviour) */
155 /* Enable this to find BN_CTX bugs */
157 static const char *ctxdbg_cur = NULL;
158 static void ctxdbg(BN_CTX *ctx)
160 unsigned int bnidx = 0, fpidx = 0;
161 BN_POOL_ITEM *item = ctx->pool.head;
162 BN_STACK *stack = &ctx->stack;
163 fprintf(stderr,"(%08x): ", (unsigned int)ctx);
164 while(bnidx < ctx->used)
166 fprintf(stderr,"%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
167 if(!(bnidx % BN_CTX_POOL_SIZE))
170 fprintf(stderr,"\n");
172 fprintf(stderr," : ");
173 while(fpidx < stack->depth)
175 while(bnidx++ < stack->indexes[fpidx])
177 fprintf(stderr,"^^^ ");
181 fprintf(stderr,"\n");
183 #define CTXDBG_ENTRY(str, ctx) do { \
184 ctxdbg_cur = (str); \
185 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
188 #define CTXDBG_EXIT(ctx) do { \
189 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
192 #define CTXDBG_RET(ctx,ret)
194 #define CTXDBG_ENTRY(str, ctx)
195 #define CTXDBG_EXIT(ctx)
196 #define CTXDBG_RET(ctx,ret)
199 /* This function is an evil legacy and should not be used. This implementation
200 * is WYSIWYG, though I've done my best. */
201 #ifndef OPENSSL_NO_DEPRECATED
202 void BN_CTX_init(BN_CTX *ctx)
204 /* Assume the caller obtained the context via BN_CTX_new() and so is
205 * trying to reset it for use. Nothing else makes sense, least of all
206 * binary compatibility from a time when they could declare a static
208 BN_POOL_reset(&ctx->pool);
209 BN_STACK_reset(&ctx->stack);
216 BN_CTX *BN_CTX_new(void)
218 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
221 BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
224 /* Initialise the structure */
225 BN_POOL_init(&ret->pool);
226 BN_STACK_init(&ret->stack);
233 void BN_CTX_free(BN_CTX *ctx)
239 BN_POOL_ITEM *pool = ctx->pool.head;
240 fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
241 ctx->stack.size, ctx->pool.size);
242 fprintf(stderr,"dmaxs: ");
245 while(loop < BN_CTX_POOL_SIZE)
246 fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
249 fprintf(stderr,"\n");
252 BN_STACK_finish(&ctx->stack);
253 BN_POOL_finish(&ctx->pool);
257 void BN_CTX_start(BN_CTX *ctx)
259 CTXDBG_ENTRY("BN_CTX_start", ctx);
260 /* If we're already overflowing ... */
261 if(ctx->err_stack || ctx->too_many)
263 /* (Try to) get a new frame pointer */
264 else if(!BN_STACK_push(&ctx->stack, ctx->used))
266 BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
272 void BN_CTX_end(BN_CTX *ctx)
274 CTXDBG_ENTRY("BN_CTX_end", ctx);
279 unsigned int fp = BN_STACK_pop(&ctx->stack);
280 /* Does this stack frame have anything to release? */
282 BN_POOL_release(&ctx->pool, ctx->used - fp);
284 /* Unjam "too_many" in case "get" had failed */
290 BIGNUM *BN_CTX_get(BN_CTX *ctx)
293 CTXDBG_ENTRY("BN_CTX_get", ctx);
294 if(ctx->err_stack || ctx->too_many) return NULL;
295 if((ret = BN_POOL_get(&ctx->pool)) == NULL)
297 /* Setting too_many prevents repeated "get" attempts from
298 * cluttering the error stack. */
300 BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
303 /* OK, make sure the returned bignum is "zero" */
306 CTXDBG_RET(ctx, ret);
314 static void BN_STACK_init(BN_STACK *st)
317 st->depth = st->size = 0;
320 static void BN_STACK_finish(BN_STACK *st)
322 if(st->size) OPENSSL_free(st->indexes);
325 #ifndef OPENSSL_NO_DEPRECATED
326 static void BN_STACK_reset(BN_STACK *st)
332 static int BN_STACK_push(BN_STACK *st, unsigned int idx)
334 if(st->depth == st->size)
337 unsigned int newsize = (st->size ?
338 (st->size * 3 / 2) : BN_CTX_START_FRAMES);
339 unsigned int *newitems = OPENSSL_malloc(newsize *
340 sizeof(unsigned int));
341 if(!newitems) return 0;
343 memcpy(newitems, st->indexes, st->depth *
344 sizeof(unsigned int));
345 if(st->size) OPENSSL_free(st->indexes);
346 st->indexes = newitems;
349 st->indexes[(st->depth)++] = idx;
353 static unsigned int BN_STACK_pop(BN_STACK *st)
355 return st->indexes[--(st->depth)];
362 static void BN_POOL_init(BN_POOL *p)
364 p->head = p->current = p->tail = NULL;
365 p->used = p->size = 0;
368 static void BN_POOL_finish(BN_POOL *p)
372 unsigned int loop = 0;
373 BIGNUM *bn = p->head->vals;
374 while(loop++ < BN_CTX_POOL_SIZE)
376 if(bn->d) BN_clear_free(bn);
379 p->current = p->head->next;
380 OPENSSL_free(p->head);
381 p->head = p->current;
385 #ifndef OPENSSL_NO_DEPRECATED
386 static void BN_POOL_reset(BN_POOL *p)
388 BN_POOL_ITEM *item = p->head;
391 unsigned int loop = 0;
392 BIGNUM *bn = item->vals;
393 while(loop++ < BN_CTX_POOL_SIZE)
395 if(bn->d) BN_clear(bn);
400 p->current = p->head;
405 static BIGNUM *BN_POOL_get(BN_POOL *p)
407 if(p->used == p->size)
410 unsigned int loop = 0;
411 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
412 if(!item) return NULL;
413 /* Initialise the structure */
415 while(loop++ < BN_CTX_POOL_SIZE)
417 item->prev = p->tail;
421 p->head = p->current = p->tail = item;
424 p->tail->next = item;
428 p->size += BN_CTX_POOL_SIZE;
430 /* Return the first bignum from the new pool */
434 p->current = p->head;
435 else if((p->used % BN_CTX_POOL_SIZE) == 0)
436 p->current = p->current->next;
437 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
440 static void BN_POOL_release(BN_POOL *p, unsigned int num)
442 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
446 bn_check_top(p->current->vals + offset);
449 offset = BN_CTX_POOL_SIZE - 1;
450 p->current = p->current->prev;