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
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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,
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44 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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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)
65 #include "internal/cryptlib.h"
71 * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
72 * check they can be safely removed.
73 * - Check +1 and other ugliness in BN_from_montgomery()
75 * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
76 * appropriate 'block' size that will be honoured by bn_expand_internal() to
77 * prevent piddly little reallocations. OTOH, profiling bignum expansions in
78 * BN_CTX doesn't show this to be a big issue.
81 /* How many bignums are in each "pool item"; */
82 #define BN_CTX_POOL_SIZE 16
83 /* The stack frame info is resizing, set a first-time expansion size; */
84 #define BN_CTX_START_FRAMES 32
90 /* A bundle of bignums that can be linked with other bundles */
91 typedef struct bignum_pool_item {
92 /* The bignum values */
93 BIGNUM vals[BN_CTX_POOL_SIZE];
94 /* Linked-list admin */
95 struct bignum_pool_item *prev, *next;
97 /* A linked-list of bignums grouped in bundles */
98 typedef struct bignum_pool {
99 /* Linked-list admin */
100 BN_POOL_ITEM *head, *current, *tail;
101 /* Stack depth and allocation size */
104 static void BN_POOL_init(BN_POOL *);
105 static void BN_POOL_finish(BN_POOL *);
106 static BIGNUM *BN_POOL_get(BN_POOL *);
107 static void BN_POOL_release(BN_POOL *, unsigned int);
113 /* A wrapper to manage the "stack frames" */
114 typedef struct bignum_ctx_stack {
115 /* Array of indexes into the bignum stack */
116 unsigned int *indexes;
117 /* Number of stack frames, and the size of the allocated array */
118 unsigned int depth, size;
120 static void BN_STACK_init(BN_STACK *);
121 static void BN_STACK_finish(BN_STACK *);
122 static int BN_STACK_push(BN_STACK *, unsigned int);
123 static unsigned int BN_STACK_pop(BN_STACK *);
129 /* The opaque BN_CTX type */
131 /* The bignum bundles */
133 /* The "stack frames", if you will */
135 /* The number of bignums currently assigned */
137 /* Depth of stack overflow */
139 /* Block "gets" until an "end" (compatibility behaviour) */
143 /* Enable this to find BN_CTX bugs */
145 static const char *ctxdbg_cur = NULL;
146 static void ctxdbg(BN_CTX *ctx)
148 unsigned int bnidx = 0, fpidx = 0;
149 BN_POOL_ITEM *item = ctx->pool.head;
150 BN_STACK *stack = &ctx->stack;
151 fprintf(stderr, "(%16p): ", ctx);
152 while (bnidx < ctx->used) {
153 fprintf(stderr, "%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
154 if (!(bnidx % BN_CTX_POOL_SIZE))
157 fprintf(stderr, "\n");
159 fprintf(stderr, " : ");
160 while (fpidx < stack->depth) {
161 while (bnidx++ < stack->indexes[fpidx])
162 fprintf(stderr, " ");
163 fprintf(stderr, "^^^ ");
167 fprintf(stderr, "\n");
170 # define CTXDBG_ENTRY(str, ctx) do { \
171 ctxdbg_cur = (str); \
172 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
175 # define CTXDBG_EXIT(ctx) do { \
176 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
179 # define CTXDBG_RET(ctx,ret)
181 # define CTXDBG_ENTRY(str, ctx)
182 # define CTXDBG_EXIT(ctx)
183 # define CTXDBG_RET(ctx,ret)
187 BN_CTX *BN_CTX_new(void)
189 BN_CTX *ret = OPENSSL_malloc(sizeof(*ret));
191 BNerr(BN_F_BN_CTX_NEW, ERR_R_MALLOC_FAILURE);
194 /* Initialise the structure */
195 BN_POOL_init(&ret->pool);
196 BN_STACK_init(&ret->stack);
203 void BN_CTX_free(BN_CTX *ctx)
209 BN_POOL_ITEM *pool = ctx->pool.head;
210 fprintf(stderr, "BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
211 ctx->stack.size, ctx->pool.size);
212 fprintf(stderr, "dmaxs: ");
215 while (loop < BN_CTX_POOL_SIZE)
216 fprintf(stderr, "%02x ", pool->vals[loop++].dmax);
219 fprintf(stderr, "\n");
222 BN_STACK_finish(&ctx->stack);
223 BN_POOL_finish(&ctx->pool);
227 void BN_CTX_start(BN_CTX *ctx)
229 CTXDBG_ENTRY("BN_CTX_start", ctx);
230 /* If we're already overflowing ... */
231 if (ctx->err_stack || ctx->too_many)
233 /* (Try to) get a new frame pointer */
234 else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
235 BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
241 void BN_CTX_end(BN_CTX *ctx)
243 CTXDBG_ENTRY("BN_CTX_end", ctx);
247 unsigned int fp = BN_STACK_pop(&ctx->stack);
248 /* Does this stack frame have anything to release? */
250 BN_POOL_release(&ctx->pool, ctx->used - fp);
252 /* Unjam "too_many" in case "get" had failed */
258 BIGNUM *BN_CTX_get(BN_CTX *ctx)
261 CTXDBG_ENTRY("BN_CTX_get", ctx);
262 if (ctx->err_stack || ctx->too_many)
264 if ((ret = BN_POOL_get(&ctx->pool)) == NULL) {
266 * Setting too_many prevents repeated "get" attempts from cluttering
270 BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
273 /* OK, make sure the returned bignum is "zero" */
276 CTXDBG_RET(ctx, ret);
284 static void BN_STACK_init(BN_STACK *st)
287 st->depth = st->size = 0;
290 static void BN_STACK_finish(BN_STACK *st)
293 OPENSSL_free(st->indexes);
297 static int BN_STACK_push(BN_STACK *st, unsigned int idx)
299 if (st->depth == st->size)
302 unsigned int newsize = (st->size ?
303 (st->size * 3 / 2) : BN_CTX_START_FRAMES);
304 unsigned int *newitems = OPENSSL_malloc(newsize *
305 sizeof(unsigned int));
309 memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int));
311 OPENSSL_free(st->indexes);
312 st->indexes = newitems;
315 st->indexes[(st->depth)++] = idx;
319 static unsigned int BN_STACK_pop(BN_STACK *st)
321 return st->indexes[--(st->depth)];
328 static void BN_POOL_init(BN_POOL *p)
330 p->head = p->current = p->tail = NULL;
331 p->used = p->size = 0;
334 static void BN_POOL_finish(BN_POOL *p)
337 unsigned int loop = 0;
338 BIGNUM *bn = p->head->vals;
339 while (loop++ < BN_CTX_POOL_SIZE) {
344 p->current = p->head->next;
345 OPENSSL_free(p->head);
346 p->head = p->current;
351 static BIGNUM *BN_POOL_get(BN_POOL *p)
353 if (p->used == p->size) {
355 unsigned int loop = 0;
356 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(*item));
359 /* Initialise the structure */
361 while (loop++ < BN_CTX_POOL_SIZE)
363 item->prev = p->tail;
367 p->head = p->current = p->tail = item;
369 p->tail->next = item;
373 p->size += BN_CTX_POOL_SIZE;
375 /* Return the first bignum from the new pool */
379 p->current = p->head;
380 else if ((p->used % BN_CTX_POOL_SIZE) == 0)
381 p->current = p->current->next;
382 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
385 static void BN_POOL_release(BN_POOL *p, unsigned int num)
387 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
390 bn_check_top(p->current->vals + offset);
392 offset = BN_CTX_POOL_SIZE - 1;
393 p->current = p->current->prev;