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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43 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 *, int);
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) */
145 /* Enable this to find BN_CTX bugs */
147 static const char *ctxdbg_cur = NULL;
148 static void ctxdbg(BN_CTX *ctx)
150 unsigned int bnidx = 0, fpidx = 0;
151 BN_POOL_ITEM *item = ctx->pool.head;
152 BN_STACK *stack = &ctx->stack;
153 fprintf(stderr, "(%16p): ", ctx);
154 while (bnidx < ctx->used) {
155 fprintf(stderr, "%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
156 if (!(bnidx % BN_CTX_POOL_SIZE))
159 fprintf(stderr, "\n");
161 fprintf(stderr, " : ");
162 while (fpidx < stack->depth) {
163 while (bnidx++ < stack->indexes[fpidx])
164 fprintf(stderr, " ");
165 fprintf(stderr, "^^^ ");
169 fprintf(stderr, "\n");
172 # define CTXDBG_ENTRY(str, ctx) do { \
173 ctxdbg_cur = (str); \
174 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
177 # define CTXDBG_EXIT(ctx) do { \
178 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
181 # define CTXDBG_RET(ctx,ret)
183 # define CTXDBG_ENTRY(str, ctx)
184 # define CTXDBG_EXIT(ctx)
185 # define CTXDBG_RET(ctx,ret)
189 BN_CTX *BN_CTX_new(void)
193 if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
194 BNerr(BN_F_BN_CTX_NEW, ERR_R_MALLOC_FAILURE);
197 /* Initialise the structure */
198 BN_POOL_init(&ret->pool);
199 BN_STACK_init(&ret->stack);
207 BN_CTX *BN_CTX_secure_new(void)
209 BN_CTX *ret = BN_CTX_new();
212 ret->flags = BN_FLG_SECURE;
216 void BN_CTX_free(BN_CTX *ctx)
222 BN_POOL_ITEM *pool = ctx->pool.head;
223 fprintf(stderr, "BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
224 ctx->stack.size, ctx->pool.size);
225 fprintf(stderr, "dmaxs: ");
228 while (loop < BN_CTX_POOL_SIZE)
229 fprintf(stderr, "%02x ", pool->vals[loop++].dmax);
232 fprintf(stderr, "\n");
235 BN_STACK_finish(&ctx->stack);
236 BN_POOL_finish(&ctx->pool);
240 void BN_CTX_start(BN_CTX *ctx)
242 CTXDBG_ENTRY("BN_CTX_start", ctx);
243 /* If we're already overflowing ... */
244 if (ctx->err_stack || ctx->too_many)
246 /* (Try to) get a new frame pointer */
247 else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
248 BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
254 void BN_CTX_end(BN_CTX *ctx)
256 CTXDBG_ENTRY("BN_CTX_end", ctx);
260 unsigned int fp = BN_STACK_pop(&ctx->stack);
261 /* Does this stack frame have anything to release? */
263 BN_POOL_release(&ctx->pool, ctx->used - fp);
265 /* Unjam "too_many" in case "get" had failed */
271 BIGNUM *BN_CTX_get(BN_CTX *ctx)
275 CTXDBG_ENTRY("BN_CTX_get", ctx);
276 if (ctx->err_stack || ctx->too_many)
278 if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) {
280 * Setting too_many prevents repeated "get" attempts from cluttering
284 BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
287 /* OK, make sure the returned bignum is "zero" */
290 CTXDBG_RET(ctx, ret);
298 static void BN_STACK_init(BN_STACK *st)
301 st->depth = st->size = 0;
304 static void BN_STACK_finish(BN_STACK *st)
306 OPENSSL_free(st->indexes);
311 static int BN_STACK_push(BN_STACK *st, unsigned int idx)
313 if (st->depth == st->size) {
315 unsigned int newsize =
316 st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES;
317 unsigned int *newitems = OPENSSL_malloc(sizeof(*newitems) * newsize);
318 if (newitems == NULL)
321 memcpy(newitems, st->indexes, sizeof(*newitems) * st->depth);
322 OPENSSL_free(st->indexes);
323 st->indexes = newitems;
326 st->indexes[(st->depth)++] = idx;
330 static unsigned int BN_STACK_pop(BN_STACK *st)
332 return st->indexes[--(st->depth)];
339 static void BN_POOL_init(BN_POOL *p)
341 p->head = p->current = p->tail = NULL;
342 p->used = p->size = 0;
345 static void BN_POOL_finish(BN_POOL *p)
351 for (loop = 0, bn = p->head->vals; loop++ < BN_CTX_POOL_SIZE; bn++)
354 p->current = p->head->next;
355 OPENSSL_free(p->head);
356 p->head = p->current;
361 static BIGNUM *BN_POOL_get(BN_POOL *p, int flag)
366 /* Full; allocate a new pool item and link it in. */
367 if (p->used == p->size) {
368 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(*item));
371 for (loop = 0, bn = item->vals; loop++ < BN_CTX_POOL_SIZE; bn++) {
373 if ((flag & BN_FLG_SECURE) != 0)
374 BN_set_flags(bn, BN_FLG_SECURE);
376 item->prev = p->tail;
380 p->head = p->current = p->tail = item;
382 p->tail->next = item;
386 p->size += BN_CTX_POOL_SIZE;
388 /* Return the first bignum from the new pool */
393 p->current = p->head;
394 else if ((p->used % BN_CTX_POOL_SIZE) == 0)
395 p->current = p->current->next;
396 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
399 static void BN_POOL_release(BN_POOL *p, unsigned int num)
401 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
405 bn_check_top(p->current->vals + offset);
407 offset = BN_CTX_POOL_SIZE - 1;
408 p->current = p->current->prev;