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 #include "../../internal.h" 63 64 65 /* How many bignums are in each "pool item"; */ 66 #define BN_CTX_POOL_SIZE 16 67 /* The stack frame info is resizing, set a first-time expansion size; */ 68 #define BN_CTX_START_FRAMES 32 69 70 /* A bundle of bignums that can be linked with other bundles */ 71 typedef struct bignum_pool_item { 72 /* The bignum values */ 73 BIGNUM vals[BN_CTX_POOL_SIZE]; 74 /* Linked-list admin */ 75 struct bignum_pool_item *prev, *next; 76 } BN_POOL_ITEM; 77 78 79 typedef struct bignum_pool { 80 /* Linked-list admin */ 81 BN_POOL_ITEM *head, *current, *tail; 82 /* Stack depth and allocation size */ 83 unsigned used, size; 84 } BN_POOL; 85 86 static void BN_POOL_init(BN_POOL *); 87 static void BN_POOL_finish(BN_POOL *); 88 static BIGNUM *BN_POOL_get(BN_POOL *); 89 static void BN_POOL_release(BN_POOL *, unsigned int); 90 91 /************/ 92 /* BN_STACK */ 93 /************/ 94 95 /* A wrapper to manage the "stack frames" */ 96 typedef struct bignum_ctx_stack { 97 /* Array of indexes into the bignum stack */ 98 unsigned int *indexes; 99 /* Number of stack frames, and the size of the allocated array */ 100 unsigned int depth, size; 101 } BN_STACK; 102 103 static void BN_STACK_init(BN_STACK *); 104 static void BN_STACK_finish(BN_STACK *); 105 static int BN_STACK_push(BN_STACK *, unsigned int); 106 static unsigned int BN_STACK_pop(BN_STACK *); 107 108 /**********/ 109 /* BN_CTX */ 110 /**********/ 111 112 /* The opaque BN_CTX type */ 113 struct bignum_ctx { 114 /* The bignum bundles */ 115 BN_POOL pool; 116 /* The "stack frames", if you will */ 117 BN_STACK stack; 118 /* The number of bignums currently assigned */ 119 unsigned int used; 120 /* Depth of stack overflow */ 121 int err_stack; 122 /* Block "gets" until an "end" (compatibility behaviour) */ 123 int too_many; 124 }; 125 126 BN_CTX *BN_CTX_new(void) { 127 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX)); 128 if (!ret) { 129 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 130 return NULL; 131 } 132 133 /* Initialise the structure */ 134 BN_POOL_init(&ret->pool); 135 BN_STACK_init(&ret->stack); 136 ret->used = 0; 137 ret->err_stack = 0; 138 ret->too_many = 0; 139 return ret; 140 } 141 142 void BN_CTX_free(BN_CTX *ctx) { 143 if (ctx == NULL) { 144 return; 145 } 146 147 BN_STACK_finish(&ctx->stack); 148 BN_POOL_finish(&ctx->pool); 149 OPENSSL_free(ctx); 150 } 151 152 void BN_CTX_start(BN_CTX *ctx) { 153 /* If we're already overflowing ... */ 154 if (ctx->err_stack || ctx->too_many) { 155 ctx->err_stack++; 156 } else if (!BN_STACK_push(&ctx->stack, ctx->used)) { 157 /* (Try to) get a new frame pointer */ 158 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES); 159 ctx->err_stack++; 160 } 161 } 162 163 BIGNUM *BN_CTX_get(BN_CTX *ctx) { 164 BIGNUM *ret; 165 if (ctx->err_stack || ctx->too_many) { 166 return NULL; 167 } 168 169 ret = BN_POOL_get(&ctx->pool); 170 if (ret == NULL) { 171 /* Setting too_many prevents repeated "get" attempts from 172 * cluttering the error stack. */ 173 ctx->too_many = 1; 174 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES); 175 return NULL; 176 } 177 178 /* OK, make sure the returned bignum is "zero" */ 179 BN_zero(ret); 180 ctx->used++; 181 return ret; 182 } 183 184 void BN_CTX_end(BN_CTX *ctx) { 185 if (ctx->err_stack) { 186 ctx->err_stack--; 187 } else { 188 unsigned int fp = BN_STACK_pop(&ctx->stack); 189 /* Does this stack frame have anything to release? */ 190 if (fp < ctx->used) { 191 BN_POOL_release(&ctx->pool, ctx->used - fp); 192 } 193 194 ctx->used = fp; 195 /* Unjam "too_many" in case "get" had failed */ 196 ctx->too_many = 0; 197 } 198 } 199 200 /************/ 201 /* BN_STACK */ 202 /************/ 203 204 static void BN_STACK_init(BN_STACK *st) { 205 st->indexes = NULL; 206 st->depth = st->size = 0; 207 } 208 209 static void BN_STACK_finish(BN_STACK *st) { 210 OPENSSL_free(st->indexes); 211 } 212 213 static int BN_STACK_push(BN_STACK *st, unsigned int idx) { 214 if (st->depth == st->size) { 215 /* Need to expand */ 216 unsigned int newsize = 217 (st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES); 218 unsigned int *newitems = OPENSSL_malloc(newsize * sizeof(unsigned int)); 219 if (!newitems) { 220 return 0; 221 } 222 if (st->depth) { 223 OPENSSL_memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int)); 224 } 225 OPENSSL_free(st->indexes); 226 st->indexes = newitems; 227 st->size = newsize; 228 } 229 230 st->indexes[(st->depth)++] = idx; 231 return 1; 232 } 233 234 static unsigned int BN_STACK_pop(BN_STACK *st) { 235 return st->indexes[--(st->depth)]; 236 } 237 238 static void BN_POOL_init(BN_POOL *p) { 239 p->head = p->current = p->tail = NULL; 240 p->used = p->size = 0; 241 } 242 243 static void BN_POOL_finish(BN_POOL *p) { 244 while (p->head) { 245 for (size_t i = 0; i < BN_CTX_POOL_SIZE; i++) { 246 BN_clear_free(&p->head->vals[i]); 247 } 248 249 p->current = p->head->next; 250 OPENSSL_free(p->head); 251 p->head = p->current; 252 } 253 } 254 255 static BIGNUM *BN_POOL_get(BN_POOL *p) { 256 if (p->used == p->size) { 257 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM)); 258 if (!item) { 259 return NULL; 260 } 261 262 /* Initialise the structure */ 263 for (size_t i = 0; i < BN_CTX_POOL_SIZE; i++) { 264 BN_init(&item->vals[i]); 265 } 266 267 item->prev = p->tail; 268 item->next = NULL; 269 /* Link it in */ 270 if (!p->head) { 271 p->head = p->current = p->tail = item; 272 } else { 273 p->tail->next = item; 274 p->tail = item; 275 p->current = item; 276 } 277 278 p->size += BN_CTX_POOL_SIZE; 279 p->used++; 280 /* Return the first bignum from the new pool */ 281 return item->vals; 282 } 283 284 if (!p->used) { 285 p->current = p->head; 286 } else if ((p->used % BN_CTX_POOL_SIZE) == 0) { 287 p->current = p->current->next; 288 } 289 290 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE); 291 } 292 293 static void BN_POOL_release(BN_POOL *p, unsigned int num) { 294 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE; 295 p->used -= num; 296 297 while (num--) { 298 if (!offset) { 299 offset = BN_CTX_POOL_SIZE - 1; 300 p->current = p->current->prev; 301 } else { 302 offset--; 303 } 304 } 305 } 306
