Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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 | |