release/src/router/openssl/crypto/bn/bn_ctx.c

   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.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  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
  16  *    distribution.
  17  *
  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/)"
  22  *
  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.
  27  *
  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.
  31  *
  32  * 6. Redistributions of any form whatsoever must retain the following
  33  *    acknowledgment:
  34  *    "This product includes software developed by the OpenSSL Project
  35  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  36  *
  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  * ====================================================================
  50  *
  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).
  54  *
  55  */
  56
  57 #if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
  58 # ifndef NDEBUG
  59 #  define NDEBUG
  60 # endif
  61 #endif
  62
  63 #include <stdio.h>
  64 #include <assert.h>
  65
  66 #include "cryptlib.h"
  67 #include "bn_lcl.h"
  68
  69 /*-
  70  * TODO list
  71  *
  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()
  75  *
  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.
  80  */
  81
  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
  86
  87 /***********/
  88 /* BN_POOL */
  89 /***********/
  90
  91 /* A bundle of bignums that can be linked with other bundles */
  92 typedef struct bignum_pool_item {
  93     /* The bignum values */
  94     BIGNUM vals[BN_CTX_POOL_SIZE];
  95     /* Linked-list admin */
  96     struct bignum_pool_item *prev, *next;
  97 } BN_POOL_ITEM;
  98 /* A linked-list of bignums grouped in bundles */
  99 typedef struct bignum_pool {
 100     /* Linked-list admin */
 101     BN_POOL_ITEM *head, *current, *tail;
 102     /* Stack depth and allocation size */
 103     unsigned used, size;
 104 } BN_POOL;
 105 static void BN_POOL_init(BN_POOL *);
 106 static void BN_POOL_finish(BN_POOL *);
 107 #ifndef OPENSSL_NO_DEPRECATED
 108 static void BN_POOL_reset(BN_POOL *);
 109 #endif
 110 static BIGNUM *BN_POOL_get(BN_POOL *);
 111 static void BN_POOL_release(BN_POOL *, unsigned int);
 112
 113 /************/
 114 /* BN_STACK */
 115 /************/
 116
 117 /* A wrapper to manage the "stack frames" */
 118 typedef struct bignum_ctx_stack {
 119     /* Array of indexes into the bignum stack */
 120     unsigned int *indexes;
 121     /* Number of stack frames, and the size of the allocated array */
 122     unsigned int depth, size;
 123 } BN_STACK;
 124 static void BN_STACK_init(BN_STACK *);
 125 static void BN_STACK_finish(BN_STACK *);
 126 #ifndef OPENSSL_NO_DEPRECATED
 127 static void BN_STACK_reset(BN_STACK *);
 128 #endif
 129 static int BN_STACK_push(BN_STACK *, unsigned int);
 130 static unsigned int BN_STACK_pop(BN_STACK *);
 131
 132 /**********/
 133 /* BN_CTX */
 134 /**********/
 135
 136 /* The opaque BN_CTX type */
 137 struct bignum_ctx {
 138     /* The bignum bundles */
 139     BN_POOL pool;
 140     /* The "stack frames", if you will */
 141     BN_STACK stack;
 142     /* The number of bignums currently assigned */
 143     unsigned int used;
 144     /* Depth of stack overflow */
 145     int err_stack;
 146     /* Block "gets" until an "end" (compatibility behaviour) */
 147     int too_many;
 148 };
 149
 150 /* Enable this to find BN_CTX bugs */
 151 #ifdef BN_CTX_DEBUG
 152 static const char *ctxdbg_cur = NULL;
 153 static void ctxdbg(BN_CTX *ctx)
 154 {
 155     unsigned int bnidx = 0, fpidx = 0;
 156     BN_POOL_ITEM *item = ctx->pool.head;
 157     BN_STACK *stack = &ctx->stack;
 158     fprintf(stderr, "(%16p): ", ctx);
 159     while (bnidx < ctx->used) {
 160         fprintf(stderr, "%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
 161         if (!(bnidx % BN_CTX_POOL_SIZE))
 162             item = item->next;
 163     }
 164     fprintf(stderr, "\n");
 165     bnidx = 0;
 166     fprintf(stderr, "          : ");
 167     while (fpidx < stack->depth) {
 168         while (bnidx++ < stack->indexes[fpidx])
 169             fprintf(stderr, "    ");
 170         fprintf(stderr, "^^^ ");
 171         bnidx++;
 172         fpidx++;
 173     }
 174     fprintf(stderr, "\n");
 175 }
 176
 177 # define CTXDBG_ENTRY(str, ctx)  do { \
 178                                 ctxdbg_cur = (str); \
 179                                 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
 180                                 ctxdbg(ctx); \
 181                                 } while(0)
 182 # define CTXDBG_EXIT(ctx)        do { \
 183                                 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
 184                                 ctxdbg(ctx); \
 185                                 } while(0)
 186 # define CTXDBG_RET(ctx,ret)
 187 #else
 188 # define CTXDBG_ENTRY(str, ctx)
 189 # define CTXDBG_EXIT(ctx)
 190 # define CTXDBG_RET(ctx,ret)
 191 #endif
 192
 193 /*
 194  * This function is an evil legacy and should not be used. This
 195  * implementation is WYSIWYG, though I've done my best.
 196  */
 197 #ifndef OPENSSL_NO_DEPRECATED
 198 void BN_CTX_init(BN_CTX *ctx)
 199 {
 200     /*
 201      * Assume the caller obtained the context via BN_CTX_new() and so is
 202      * trying to reset it for use. Nothing else makes sense, least of all
 203      * binary compatibility from a time when they could declare a static
 204      * variable.
 205      */
 206     BN_POOL_reset(&ctx->pool);
 207     BN_STACK_reset(&ctx->stack);
 208     ctx->used = 0;
 209     ctx->err_stack = 0;
 210     ctx->too_many = 0;
 211 }
 212 #endif
 213
 214 BN_CTX *BN_CTX_new(void)
 215 {
 216     BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
 217     if (!ret) {
 218         BNerr(BN_F_BN_CTX_NEW, ERR_R_MALLOC_FAILURE);
 219         return NULL;
 220     }
 221     /* Initialise the structure */
 222     BN_POOL_init(&ret->pool);
 223     BN_STACK_init(&ret->stack);
 224     ret->used = 0;
 225     ret->err_stack = 0;
 226     ret->too_many = 0;
 227     return ret;
 228 }
 229
 230 void BN_CTX_free(BN_CTX *ctx)
 231 {
 232     if (ctx == NULL)
 233         return;
 234 #ifdef BN_CTX_DEBUG
 235     {
 236         BN_POOL_ITEM *pool = ctx->pool.head;
 237         fprintf(stderr, "BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
 238                 ctx->stack.size, ctx->pool.size);
 239         fprintf(stderr, "dmaxs: ");
 240         while (pool) {
 241             unsigned loop = 0;
 242             while (loop < BN_CTX_POOL_SIZE)
 243                 fprintf(stderr, "%02x ", pool->vals[loop++].dmax);
 244             pool = pool->next;
 245         }
 246         fprintf(stderr, "\n");
 247     }
 248 #endif
 249     BN_STACK_finish(&ctx->stack);
 250     BN_POOL_finish(&ctx->pool);
 251     OPENSSL_free(ctx);
 252 }
 253
 254 void BN_CTX_start(BN_CTX *ctx)
 255 {
 256     CTXDBG_ENTRY("BN_CTX_start", ctx);
 257     /* If we're already overflowing ... */
 258     if (ctx->err_stack || ctx->too_many)
 259         ctx->err_stack++;
 260     /* (Try to) get a new frame pointer */
 261     else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
 262         BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
 263         ctx->err_stack++;
 264     }
 265     CTXDBG_EXIT(ctx);
 266 }
 267
 268 void BN_CTX_end(BN_CTX *ctx)
 269 {
 270     CTXDBG_ENTRY("BN_CTX_end", ctx);
 271     if (ctx->err_stack)
 272         ctx->err_stack--;
 273     else {
 274         unsigned int fp = BN_STACK_pop(&ctx->stack);
 275         /* Does this stack frame have anything to release? */
 276         if (fp < ctx->used)
 277             BN_POOL_release(&ctx->pool, ctx->used - fp);
 278         ctx->used = fp;
 279         /* Unjam "too_many" in case "get" had failed */
 280         ctx->too_many = 0;
 281     }
 282     CTXDBG_EXIT(ctx);
 283 }
 284
 285 BIGNUM *BN_CTX_get(BN_CTX *ctx)
 286 {
 287     BIGNUM *ret;
 288     CTXDBG_ENTRY("BN_CTX_get", ctx);
 289     if (ctx->err_stack || ctx->too_many)
 290         return NULL;
 291     if ((ret = BN_POOL_get(&ctx->pool)) == NULL) {
 292         /*
 293          * Setting too_many prevents repeated "get" attempts from cluttering
 294          * the error stack.
 295          */
 296         ctx->too_many = 1;
 297         BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
 298         return NULL;
 299     }
 300     /* OK, make sure the returned bignum is "zero" */
 301     BN_zero(ret);
 302     ctx->used++;
 303     CTXDBG_RET(ctx, ret);
 304     return ret;
 305 }
 306
 307 /************/
 308 /* BN_STACK */
 309 /************/
 310
 311 static void BN_STACK_init(BN_STACK *st)
 312 {
 313     st->indexes = NULL;
 314     st->depth = st->size = 0;
 315 }
 316
 317 static void BN_STACK_finish(BN_STACK *st)
 318 {
 319     if (st->size)
 320         OPENSSL_free(st->indexes);
 321 }
 322
 323 #ifndef OPENSSL_NO_DEPRECATED
 324 static void BN_STACK_reset(BN_STACK *st)
 325 {
 326     st->depth = 0;
 327 }
 328 #endif
 329
 330 static int BN_STACK_push(BN_STACK *st, unsigned int idx)
 331 {
 332     if (st->depth == st->size)
 333         /* Need to expand */
 334     {
 335         unsigned int newsize = (st->size ?
 336                                 (st->size * 3 / 2) : BN_CTX_START_FRAMES);
 337         unsigned int *newitems = OPENSSL_malloc(newsize *
 338                                                 sizeof(unsigned int));
 339         if (!newitems)
 340             return 0;
 341         if (st->depth)
 342             memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int));
 343         if (st->size)
 344             OPENSSL_free(st->indexes);
 345         st->indexes = newitems;
 346         st->size = newsize;
 347     }
 348     st->indexes[(st->depth)++] = idx;
 349     return 1;
 350 }
 351
 352 static unsigned int BN_STACK_pop(BN_STACK *st)
 353 {
 354     return st->indexes[--(st->depth)];
 355 }
 356
 357 /***********/
 358 /* BN_POOL */
 359 /***********/
 360
 361 static void BN_POOL_init(BN_POOL *p)
 362 {
 363     p->head = p->current = p->tail = NULL;
 364     p->used = p->size = 0;
 365 }
 366
 367 static void BN_POOL_finish(BN_POOL *p)
 368 {
 369     while (p->head) {
 370         unsigned int loop = 0;
 371         BIGNUM *bn = p->head->vals;
 372         while (loop++ < BN_CTX_POOL_SIZE) {
 373             if (bn->d)
 374                 BN_clear_free(bn);
 375             bn++;
 376         }
 377         p->current = p->head->next;
 378         OPENSSL_free(p->head);
 379         p->head = p->current;
 380     }
 381 }
 382
 383 #ifndef OPENSSL_NO_DEPRECATED
 384 static void BN_POOL_reset(BN_POOL *p)
 385 {
 386     BN_POOL_ITEM *item = p->head;
 387     while (item) {
 388         unsigned int loop = 0;
 389         BIGNUM *bn = item->vals;
 390         while (loop++ < BN_CTX_POOL_SIZE) {
 391             if (bn->d)
 392                 BN_clear(bn);
 393             bn++;
 394         }
 395         item = item->next;
 396     }
 397     p->current = p->head;
 398     p->used = 0;
 399 }
 400 #endif
 401
 402 static BIGNUM *BN_POOL_get(BN_POOL *p)
 403 {
 404     if (p->used == p->size) {
 405         BIGNUM *bn;
 406         unsigned int loop = 0;
 407         BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
 408         if (!item)
 409             return NULL;
 410         /* Initialise the structure */
 411         bn = item->vals;
 412         while (loop++ < BN_CTX_POOL_SIZE)
 413             BN_init(bn++);
 414         item->prev = p->tail;
 415         item->next = NULL;
 416         /* Link it in */
 417         if (!p->head)
 418             p->head = p->current = p->tail = item;
 419         else {
 420             p->tail->next = item;
 421             p->tail = item;
 422             p->current = item;
 423         }
 424         p->size += BN_CTX_POOL_SIZE;
 425         p->used++;
 426         /* Return the first bignum from the new pool */
 427         return item->vals;
 428     }
 429     if (!p->used)
 430         p->current = p->head;
 431     else if ((p->used % BN_CTX_POOL_SIZE) == 0)
 432         p->current = p->current->next;
 433     return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
 434 }
 435
 436 static void BN_POOL_release(BN_POOL *p, unsigned int num)
 437 {
 438     unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
 439     p->used -= num;
 440     while (num--) {
 441         bn_check_top(p->current->vals + offset);
 442         if (!offset) {
 443             offset = BN_CTX_POOL_SIZE - 1;
 444             p->current = p->current->prev;
 445         } else
 446             offset--;
 447     }
 448 }