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 /* TODO list
  70  *
  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()
  74  *
  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.
  79  */
  80
  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
  85
  86 /***********/
  87 /* BN_POOL */
  88 /***********/
  89
  90 /* A bundle of bignums that can be linked with other bundles */
  91 typedef struct bignum_pool_item
  92         {
  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         {
 101         /* Linked-list admin */
 102         BN_POOL_ITEM *head, *current, *tail;
 103         /* Stack depth and allocation size */
 104         unsigned used, size;
 105         } BN_POOL;
 106 static void             BN_POOL_init(BN_POOL *);
 107 static void             BN_POOL_finish(BN_POOL *);
 108 #ifndef OPENSSL_NO_DEPRECATED
 109 static void             BN_POOL_reset(BN_POOL *);
 110 #endif
 111 static BIGNUM *         BN_POOL_get(BN_POOL *);
 112 static void             BN_POOL_release(BN_POOL *, unsigned int);
 113
 114 /************/
 115 /* BN_STACK */
 116 /************/
 117
 118 /* A wrapper to manage the "stack frames" */
 119 typedef struct bignum_ctx_stack
 120         {
 121         /* Array of indexes into the bignum stack */
 122         unsigned int *indexes;
 123         /* Number of stack frames, and the size of the allocated array */
 124         unsigned int depth, size;
 125         } BN_STACK;
 126 static void             BN_STACK_init(BN_STACK *);
 127 static void             BN_STACK_finish(BN_STACK *);
 128 #ifndef OPENSSL_NO_DEPRECATED
 129 static void             BN_STACK_reset(BN_STACK *);
 130 #endif
 131 static int              BN_STACK_push(BN_STACK *, unsigned int);
 132 static unsigned int     BN_STACK_pop(BN_STACK *);
 133
 134 /**********/
 135 /* BN_CTX */
 136 /**********/
 137
 138 /* The opaque BN_CTX type */
 139 struct bignum_ctx
 140         {
 141         /* The bignum bundles */
 142         BN_POOL pool;
 143         /* The "stack frames", if you will */
 144         BN_STACK stack;
 145         /* The number of bignums currently assigned */
 146         unsigned int used;
 147         /* Depth of stack overflow */
 148         int err_stack;
 149         /* Block "gets" until an "end" (compatibility behaviour) */
 150         int too_many;
 151         };
 152
 153 /* Enable this to find BN_CTX bugs */
 154 #ifdef BN_CTX_DEBUG
 155 static const char *ctxdbg_cur = NULL;
 156 static void ctxdbg(BN_CTX *ctx)
 157         {
 158         unsigned int bnidx = 0, fpidx = 0;
 159         BN_POOL_ITEM *item = ctx->pool.head;
 160         BN_STACK *stack = &ctx->stack;
 161         fprintf(stderr,"(%08x): ", (unsigned int)ctx);
 162         while(bnidx < ctx->used)
 163                 {
 164                 fprintf(stderr,"%03x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
 165                 if(!(bnidx % BN_CTX_POOL_SIZE))
 166                         item = item->next;
 167                 }
 168         fprintf(stderr,"\n");
 169         bnidx = 0;
 170         fprintf(stderr,"          : ");
 171         while(fpidx < stack->depth)
 172                 {
 173                 while(bnidx++ < stack->indexes[fpidx])
 174                         fprintf(stderr,"    ");
 175                 fprintf(stderr,"^^^ ");
 176                 bnidx++;
 177                 fpidx++;
 178                 }
 179         fprintf(stderr,"\n");
 180         }
 181 #define CTXDBG_ENTRY(str, ctx)  do { \
 182                                 ctxdbg_cur = (str); \
 183                                 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
 184                                 ctxdbg(ctx); \
 185                                 } while(0)
 186 #define CTXDBG_EXIT(ctx)        do { \
 187                                 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
 188                                 ctxdbg(ctx); \
 189                                 } while(0)
 190 #define CTXDBG_RET(ctx,ret)
 191 #else
 192 #define CTXDBG_ENTRY(str, ctx)
 193 #define CTXDBG_EXIT(ctx)
 194 #define CTXDBG_RET(ctx,ret)
 195 #endif
 196
 197 /* This function is an evil legacy and should not be used. This implementation
 198  * is WYSIWYG, though I've done my best. */
 199 #ifndef OPENSSL_NO_DEPRECATED
 200 void BN_CTX_init(BN_CTX *ctx)
 201         {
 202         /* Assume the caller obtained the context via BN_CTX_new() and so is
 203          * trying to reset it for use. Nothing else makes sense, least of all
 204          * binary compatibility from a time when they could declare a static
 205          * variable. */
 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                 {
 219                 BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
 220                 return NULL;
 221                 }
 222         /* Initialise the structure */
 223         BN_POOL_init(&ret->pool);
 224         BN_STACK_init(&ret->stack);
 225         ret->used = 0;
 226         ret->err_stack = 0;
 227         ret->too_many = 0;
 228         return ret;
 229         }
 230
 231 void BN_CTX_free(BN_CTX *ctx)
 232         {
 233         if (ctx == NULL)
 234                 return;
 235 #ifdef BN_CTX_DEBUG
 236         {
 237         BN_POOL_ITEM *pool = ctx->pool.head;
 238         fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
 239                 ctx->stack.size, ctx->pool.size);
 240         fprintf(stderr,"dmaxs: ");
 241         while(pool) {
 242                 unsigned loop = 0;
 243                 while(loop < BN_CTX_POOL_SIZE)
 244                         fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
 245                 pool = pool->next;
 246         }
 247         fprintf(stderr,"\n");
 248         }
 249 #endif
 250         BN_STACK_finish(&ctx->stack);
 251         BN_POOL_finish(&ctx->pool);
 252         OPENSSL_free(ctx);
 253         }
 254
 255 void BN_CTX_start(BN_CTX *ctx)
 256         {
 257         CTXDBG_ENTRY("BN_CTX_start", ctx);
 258         /* If we're already overflowing ... */
 259         if(ctx->err_stack || ctx->too_many)
 260                 ctx->err_stack++;
 261         /* (Try to) get a new frame pointer */
 262         else if(!BN_STACK_push(&ctx->stack, ctx->used))
 263                 {
 264                 BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
 265                 ctx->err_stack++;
 266                 }
 267         CTXDBG_EXIT(ctx);
 268         }
 269
 270 void BN_CTX_end(BN_CTX *ctx)
 271         {
 272         CTXDBG_ENTRY("BN_CTX_end", ctx);
 273         if(ctx->err_stack)
 274                 ctx->err_stack--;
 275         else
 276                 {
 277                 unsigned int fp = BN_STACK_pop(&ctx->stack);
 278                 /* Does this stack frame have anything to release? */
 279                 if(fp < ctx->used)
 280                         BN_POOL_release(&ctx->pool, ctx->used - fp);
 281                 ctx->used = fp;
 282                 /* Unjam "too_many" in case "get" had failed */
 283                 ctx->too_many = 0;
 284                 }
 285         CTXDBG_EXIT(ctx);
 286         }
 287
 288 BIGNUM *BN_CTX_get(BN_CTX *ctx)
 289         {
 290         BIGNUM *ret;
 291         CTXDBG_ENTRY("BN_CTX_get", ctx);
 292         if(ctx->err_stack || ctx->too_many) return NULL;
 293         if((ret = BN_POOL_get(&ctx->pool)) == NULL)
 294                 {
 295                 /* Setting too_many prevents repeated "get" attempts from
 296                  * cluttering the error stack. */
 297                 ctx->too_many = 1;
 298                 BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
 299                 return NULL;
 300                 }
 301         /* OK, make sure the returned bignum is "zero" */
 302         BN_zero(ret);
 303         ctx->used++;
 304         CTXDBG_RET(ctx, ret);
 305         return ret;
 306         }
 307
 308 /************/
 309 /* BN_STACK */
 310 /************/
 311
 312 static void BN_STACK_init(BN_STACK *st)
 313         {
 314         st->indexes = NULL;
 315         st->depth = st->size = 0;
 316         }
 317
 318 static void BN_STACK_finish(BN_STACK *st)
 319         {
 320         if(st->size) 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) return 0;
 340                 if(st->depth)
 341                         memcpy(newitems, st->indexes, st->depth *
 342                                                 sizeof(unsigned int));
 343                 if(st->size) OPENSSL_free(st->indexes);
 344                 st->indexes = newitems;
 345                 st->size = newsize;
 346                 }
 347         st->indexes[(st->depth)++] = idx;
 348         return 1;
 349         }
 350
 351 static unsigned int BN_STACK_pop(BN_STACK *st)
 352         {
 353         return st->indexes[--(st->depth)];
 354         }
 355
 356 /***********/
 357 /* BN_POOL */
 358 /***********/
 359
 360 static void BN_POOL_init(BN_POOL *p)
 361         {
 362         p->head = p->current = p->tail = NULL;
 363         p->used = p->size = 0;
 364         }
 365
 366 static void BN_POOL_finish(BN_POOL *p)
 367         {
 368         while(p->head)
 369                 {
 370                 unsigned int loop = 0;
 371                 BIGNUM *bn = p->head->vals;
 372                 while(loop++ < BN_CTX_POOL_SIZE)
 373                         {
 374                         if(bn->d) 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                 {
 389                 unsigned int loop = 0;
 390                 BIGNUM *bn = item->vals;
 391                 while(loop++ < BN_CTX_POOL_SIZE)
 392                         {
 393                         if(bn->d) BN_clear(bn);
 394                         bn++;
 395                         }
 396                 item = item->next;
 397                 }
 398         p->current = p->head;
 399         p->used = 0;
 400         }
 401 #endif
 402
 403 static BIGNUM *BN_POOL_get(BN_POOL *p)
 404         {
 405         if(p->used == p->size)
 406                 {
 407                 BIGNUM *bn;
 408                 unsigned int loop = 0;
 409                 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
 410                 if(!item) return NULL;
 411                 /* Initialise the structure */
 412                 bn = item->vals;
 413                 while(loop++ < BN_CTX_POOL_SIZE)
 414                         BN_init(bn++);
 415                 item->prev = p->tail;
 416                 item->next = NULL;
 417                 /* Link it in */
 418                 if(!p->head)
 419                         p->head = p->current = p->tail = item;
 420                 else
 421                         {
 422                         p->tail->next = item;
 423                         p->tail = item;
 424                         p->current = item;
 425                         }
 426                 p->size += BN_CTX_POOL_SIZE;
 427                 p->used++;
 428                 /* Return the first bignum from the new pool */
 429                 return item->vals;
 430                 }
 431         if(!p->used)
 432                 p->current = p->head;
 433         else if((p->used % BN_CTX_POOL_SIZE) == 0)
 434                 p->current = p->current->next;
 435         return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
 436         }
 437
 438 static void BN_POOL_release(BN_POOL *p, unsigned int num)
 439         {
 440         unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
 441         p->used -= num;
 442         while(num--)
 443                 {
 444                 bn_check_top(p->current->vals + offset);
 445                 if(!offset)
 446                         {
 447                         offset = BN_CTX_POOL_SIZE - 1;
 448                         p->current = p->current->prev;
 449                         }
 450                 else
 451                         offset--;
 452                 }
 453         }
 454