1 /* Written by Ulf Moeller for the OpenSSL project. */ 2 /* ==================================================================== 3 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in 14 * the documentation and/or other materials provided with the 15 * distribution. 16 * 17 * 3. All advertising materials mentioning features or use of this 18 * software must display the following acknowledgment: 19 * "This product includes software developed by the OpenSSL Project 20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 21 * 22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 23 * endorse or promote products derived from this software without 24 * prior written permission. For written permission, please contact 25 * openssl-core (at) openssl.org. 26 * 27 * 5. Products derived from this software may not be called "OpenSSL" 28 * nor may "OpenSSL" appear in their names without prior written 29 * permission of the OpenSSL Project. 30 * 31 * 6. Redistributions of any form whatsoever must retain the following 32 * acknowledgment: 33 * "This product includes software developed by the OpenSSL Project 34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 35 * 36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 47 * OF THE POSSIBILITY OF SUCH DAMAGE. 48 * ==================================================================== 49 * 50 * This product includes cryptographic software written by Eric Young 51 * (eay (at) cryptsoft.com). This product includes software written by Tim 52 * Hudson (tjh (at) cryptsoft.com). */ 53 54 55 #include <openssl/bn.h> 56 57 #include <string.h> 58 59 #include <openssl/err.h> 60 #include <openssl/mem.h> 61 62 63 /* How many bignums are in each "pool item"; */ 64 #define BN_CTX_POOL_SIZE 16 65 /* The stack frame info is resizing, set a first-time expansion size; */ 66 #define BN_CTX_START_FRAMES 32 67 68 /* A bundle of bignums that can be linked with other bundles */ 69 typedef struct bignum_pool_item { 70 /* The bignum values */ 71 BIGNUM vals[BN_CTX_POOL_SIZE]; 72 /* Linked-list admin */ 73 struct bignum_pool_item *prev, *next; 74 } BN_POOL_ITEM; 75 76 77 typedef struct bignum_pool { 78 /* Linked-list admin */ 79 BN_POOL_ITEM *head, *current, *tail; 80 /* Stack depth and allocation size */ 81 unsigned used, size; 82 } BN_POOL; 83 84 static void BN_POOL_init(BN_POOL *); 85 static void BN_POOL_finish(BN_POOL *); 86 static BIGNUM *BN_POOL_get(BN_POOL *); 87 static void BN_POOL_release(BN_POOL *, unsigned int); 88 89 /************/ 90 /* BN_STACK */ 91 /************/ 92 93 /* A wrapper to manage the "stack frames" */ 94 typedef struct bignum_ctx_stack { 95 /* Array of indexes into the bignum stack */ 96 unsigned int *indexes; 97 /* Number of stack frames, and the size of the allocated array */ 98 unsigned int depth, size; 99 } BN_STACK; 100 101 static void BN_STACK_init(BN_STACK *); 102 static void BN_STACK_finish(BN_STACK *); 103 static int BN_STACK_push(BN_STACK *, unsigned int); 104 static unsigned int BN_STACK_pop(BN_STACK *); 105 106 /**********/ 107 /* BN_CTX */ 108 /**********/ 109 110 /* The opaque BN_CTX type */ 111 struct bignum_ctx { 112 /* The bignum bundles */ 113 BN_POOL pool; 114 /* The "stack frames", if you will */ 115 BN_STACK stack; 116 /* The number of bignums currently assigned */ 117 unsigned int used; 118 /* Depth of stack overflow */ 119 int err_stack; 120 /* Block "gets" until an "end" (compatibility behaviour) */ 121 int too_many; 122 }; 123 124 BN_CTX *BN_CTX_new(void) { 125 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX)); 126 if (!ret) { 127 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 128 return NULL; 129 } 130 131 /* Initialise the structure */ 132 BN_POOL_init(&ret->pool); 133 BN_STACK_init(&ret->stack); 134 ret->used = 0; 135 ret->err_stack = 0; 136 ret->too_many = 0; 137 return ret; 138 } 139 140 void BN_CTX_free(BN_CTX *ctx) { 141 if (ctx == NULL) { 142 return; 143 } 144 145 BN_STACK_finish(&ctx->stack); 146 BN_POOL_finish(&ctx->pool); 147 OPENSSL_free(ctx); 148 } 149 150 void BN_CTX_start(BN_CTX *ctx) { 151 /* If we're already overflowing ... */ 152 if (ctx->err_stack || ctx->too_many) { 153 ctx->err_stack++; 154 } else if (!BN_STACK_push(&ctx->stack, ctx->used)) { 155 /* (Try to) get a new frame pointer */ 156 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES); 157 ctx->err_stack++; 158 } 159 } 160 161 BIGNUM *BN_CTX_get(BN_CTX *ctx) { 162 BIGNUM *ret; 163 if (ctx->err_stack || ctx->too_many) { 164 return NULL; 165 } 166 167 ret = BN_POOL_get(&ctx->pool); 168 if (ret == NULL) { 169 /* Setting too_many prevents repeated "get" attempts from 170 * cluttering the error stack. */ 171 ctx->too_many = 1; 172 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES); 173 return NULL; 174 } 175 176 /* OK, make sure the returned bignum is "zero" */ 177 BN_zero(ret); 178 ctx->used++; 179 return ret; 180 } 181 182 void BN_CTX_end(BN_CTX *ctx) { 183 if (ctx->err_stack) { 184 ctx->err_stack--; 185 } else { 186 unsigned int fp = BN_STACK_pop(&ctx->stack); 187 /* Does this stack frame have anything to release? */ 188 if (fp < ctx->used) { 189 BN_POOL_release(&ctx->pool, ctx->used - fp); 190 } 191 192 ctx->used = fp; 193 /* Unjam "too_many" in case "get" had failed */ 194 ctx->too_many = 0; 195 } 196 } 197 198 /************/ 199 /* BN_STACK */ 200 /************/ 201 202 static void BN_STACK_init(BN_STACK *st) { 203 st->indexes = NULL; 204 st->depth = st->size = 0; 205 } 206 207 static void BN_STACK_finish(BN_STACK *st) { 208 OPENSSL_free(st->indexes); 209 } 210 211 static int BN_STACK_push(BN_STACK *st, unsigned int idx) { 212 if (st->depth == st->size) { 213 /* Need to expand */ 214 unsigned int newsize = 215 (st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES); 216 unsigned int *newitems = OPENSSL_malloc(newsize * sizeof(unsigned int)); 217 if (!newitems) { 218 return 0; 219 } 220 if (st->depth) { 221 memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int)); 222 } 223 OPENSSL_free(st->indexes); 224 st->indexes = newitems; 225 st->size = newsize; 226 } 227 228 st->indexes[(st->depth)++] = idx; 229 return 1; 230 } 231 232 static unsigned int BN_STACK_pop(BN_STACK *st) { 233 return st->indexes[--(st->depth)]; 234 } 235 236 static void BN_POOL_init(BN_POOL *p) { 237 p->head = p->current = p->tail = NULL; 238 p->used = p->size = 0; 239 } 240 241 static void BN_POOL_finish(BN_POOL *p) { 242 while (p->head) { 243 unsigned int loop = 0; 244 BIGNUM *bn = p->head->vals; 245 while (loop++ < BN_CTX_POOL_SIZE) { 246 if (bn->d) { 247 BN_clear_free(bn); 248 } 249 bn++; 250 } 251 252 p->current = p->head->next; 253 OPENSSL_free(p->head); 254 p->head = p->current; 255 } 256 } 257 258 static BIGNUM *BN_POOL_get(BN_POOL *p) { 259 if (p->used == p->size) { 260 BIGNUM *bn; 261 unsigned int loop = 0; 262 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM)); 263 if (!item) { 264 return NULL; 265 } 266 267 /* Initialise the structure */ 268 bn = item->vals; 269 while (loop++ < BN_CTX_POOL_SIZE) { 270 BN_init(bn++); 271 } 272 273 item->prev = p->tail; 274 item->next = NULL; 275 /* Link it in */ 276 if (!p->head) { 277 p->head = p->current = p->tail = item; 278 } else { 279 p->tail->next = item; 280 p->tail = item; 281 p->current = item; 282 } 283 284 p->size += BN_CTX_POOL_SIZE; 285 p->used++; 286 /* Return the first bignum from the new pool */ 287 return item->vals; 288 } 289 290 if (!p->used) { 291 p->current = p->head; 292 } else if ((p->used % BN_CTX_POOL_SIZE) == 0) { 293 p->current = p->current->next; 294 } 295 296 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE); 297 } 298 299 static void BN_POOL_release(BN_POOL *p, unsigned int num) { 300 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE; 301 p->used -= num; 302 303 while (num--) { 304 if (!offset) { 305 offset = BN_CTX_POOL_SIZE - 1; 306 p->current = p->current->prev; 307 } else { 308 offset--; 309 } 310 } 311 } 312
