1 /* crypto/evp/bio_ok.c */ 2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay (at) cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay (at) cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 59 /* 60 From: Arne Ansper <arne (at) cyber.ee> 61 62 Why BIO_f_reliable? 63 64 I wrote function which took BIO* as argument, read data from it 65 and processed it. Then I wanted to store the input file in 66 encrypted form. OK I pushed BIO_f_cipher to the BIO stack 67 and everything was OK. BUT if user types wrong password 68 BIO_f_cipher outputs only garbage and my function crashes. Yes 69 I can and I should fix my function, but BIO_f_cipher is 70 easy way to add encryption support to many existing applications 71 and it's hard to debug and fix them all. 72 73 So I wanted another BIO which would catch the incorrect passwords and 74 file damages which cause garbage on BIO_f_cipher's output. 75 76 The easy way is to push the BIO_f_md and save the checksum at 77 the end of the file. However there are several problems with this 78 approach: 79 80 1) you must somehow separate checksum from actual data. 81 2) you need lot's of memory when reading the file, because you 82 must read to the end of the file and verify the checksum before 83 letting the application to read the data. 84 85 BIO_f_reliable tries to solve both problems, so that you can 86 read and write arbitrary long streams using only fixed amount 87 of memory. 88 89 BIO_f_reliable splits data stream into blocks. Each block is prefixed 90 with it's length and suffixed with it's digest. So you need only 91 several Kbytes of memory to buffer single block before verifying 92 it's digest. 93 94 BIO_f_reliable goes further and adds several important capabilities: 95 96 1) the digest of the block is computed over the whole stream 97 -- so nobody can rearrange the blocks or remove or replace them. 98 99 2) to detect invalid passwords right at the start BIO_f_reliable 100 adds special prefix to the stream. In order to avoid known plain-text 101 attacks this prefix is generated as follows: 102 103 *) digest is initialized with random seed instead of 104 standardized one. 105 *) same seed is written to output 106 *) well-known text is then hashed and the output 107 of the digest is also written to output. 108 109 reader can now read the seed from stream, hash the same string 110 and then compare the digest output. 111 112 Bad things: BIO_f_reliable knows what's going on in EVP_Digest. I 113 initially wrote and tested this code on x86 machine and wrote the 114 digests out in machine-dependent order :( There are people using 115 this code and I cannot change this easily without making existing 116 data files unreadable. 117 118 */ 119 120 #include <stdio.h> 121 #include <errno.h> 122 #include <assert.h> 123 #include "cryptlib.h" 124 #include <openssl/buffer.h> 125 #include <openssl/bio.h> 126 #include <openssl/evp.h> 127 #include <openssl/rand.h> 128 129 static int ok_write(BIO *h, const char *buf, int num); 130 static int ok_read(BIO *h, char *buf, int size); 131 static long ok_ctrl(BIO *h, int cmd, long arg1, void *arg2); 132 static int ok_new(BIO *h); 133 static int ok_free(BIO *data); 134 static long ok_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp); 135 136 static int sig_out(BIO* b); 137 static int sig_in(BIO* b); 138 static int block_out(BIO* b); 139 static int block_in(BIO* b); 140 #define OK_BLOCK_SIZE (1024*4) 141 #define OK_BLOCK_BLOCK 4 142 #define IOBS (OK_BLOCK_SIZE+ OK_BLOCK_BLOCK+ 3*EVP_MAX_MD_SIZE) 143 #define WELLKNOWN "The quick brown fox jumped over the lazy dog's back." 144 145 typedef struct ok_struct 146 { 147 size_t buf_len; 148 size_t buf_off; 149 size_t buf_len_save; 150 size_t buf_off_save; 151 int cont; /* <= 0 when finished */ 152 int finished; 153 EVP_MD_CTX md; 154 int blockout; /* output block is ready */ 155 int sigio; /* must process signature */ 156 unsigned char buf[IOBS]; 157 } BIO_OK_CTX; 158 159 static BIO_METHOD methods_ok= 160 { 161 BIO_TYPE_CIPHER,"reliable", 162 ok_write, 163 ok_read, 164 NULL, /* ok_puts, */ 165 NULL, /* ok_gets, */ 166 ok_ctrl, 167 ok_new, 168 ok_free, 169 ok_callback_ctrl, 170 }; 171 172 BIO_METHOD *BIO_f_reliable(void) 173 { 174 return(&methods_ok); 175 } 176 177 static int ok_new(BIO *bi) 178 { 179 BIO_OK_CTX *ctx; 180 181 ctx=(BIO_OK_CTX *)OPENSSL_malloc(sizeof(BIO_OK_CTX)); 182 if (ctx == NULL) return(0); 183 184 ctx->buf_len=0; 185 ctx->buf_off=0; 186 ctx->buf_len_save=0; 187 ctx->buf_off_save=0; 188 ctx->cont=1; 189 ctx->finished=0; 190 ctx->blockout= 0; 191 ctx->sigio=1; 192 193 EVP_MD_CTX_init(&ctx->md); 194 195 bi->init=0; 196 bi->ptr=(char *)ctx; 197 bi->flags=0; 198 return(1); 199 } 200 201 static int ok_free(BIO *a) 202 { 203 if (a == NULL) return(0); 204 EVP_MD_CTX_cleanup(&((BIO_OK_CTX *)a->ptr)->md); 205 OPENSSL_cleanse(a->ptr,sizeof(BIO_OK_CTX)); 206 OPENSSL_free(a->ptr); 207 a->ptr=NULL; 208 a->init=0; 209 a->flags=0; 210 return(1); 211 } 212 213 static int ok_read(BIO *b, char *out, int outl) 214 { 215 int ret=0,i,n; 216 BIO_OK_CTX *ctx; 217 218 if (out == NULL) return(0); 219 ctx=(BIO_OK_CTX *)b->ptr; 220 221 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0); 222 223 while(outl > 0) 224 { 225 226 /* copy clean bytes to output buffer */ 227 if (ctx->blockout) 228 { 229 i=ctx->buf_len-ctx->buf_off; 230 if (i > outl) i=outl; 231 memcpy(out,&(ctx->buf[ctx->buf_off]),i); 232 ret+=i; 233 out+=i; 234 outl-=i; 235 ctx->buf_off+=i; 236 237 /* all clean bytes are out */ 238 if (ctx->buf_len == ctx->buf_off) 239 { 240 ctx->buf_off=0; 241 242 /* copy start of the next block into proper place */ 243 if(ctx->buf_len_save- ctx->buf_off_save > 0) 244 { 245 ctx->buf_len= ctx->buf_len_save- ctx->buf_off_save; 246 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]), 247 ctx->buf_len); 248 } 249 else 250 { 251 ctx->buf_len=0; 252 } 253 ctx->blockout= 0; 254 } 255 } 256 257 /* output buffer full -- cancel */ 258 if (outl == 0) break; 259 260 /* no clean bytes in buffer -- fill it */ 261 n=IOBS- ctx->buf_len; 262 i=BIO_read(b->next_bio,&(ctx->buf[ctx->buf_len]),n); 263 264 if (i <= 0) break; /* nothing new */ 265 266 ctx->buf_len+= i; 267 268 /* no signature yet -- check if we got one */ 269 if (ctx->sigio == 1) 270 { 271 if (!sig_in(b)) 272 { 273 BIO_clear_retry_flags(b); 274 return 0; 275 } 276 } 277 278 /* signature ok -- check if we got block */ 279 if (ctx->sigio == 0) 280 { 281 if (!block_in(b)) 282 { 283 BIO_clear_retry_flags(b); 284 return 0; 285 } 286 } 287 288 /* invalid block -- cancel */ 289 if (ctx->cont <= 0) break; 290 291 } 292 293 BIO_clear_retry_flags(b); 294 BIO_copy_next_retry(b); 295 return(ret); 296 } 297 298 static int ok_write(BIO *b, const char *in, int inl) 299 { 300 int ret=0,n,i; 301 BIO_OK_CTX *ctx; 302 303 if (inl <= 0) return inl; 304 305 ctx=(BIO_OK_CTX *)b->ptr; 306 ret=inl; 307 308 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0); 309 310 if(ctx->sigio && !sig_out(b)) 311 return 0; 312 313 do{ 314 BIO_clear_retry_flags(b); 315 n=ctx->buf_len-ctx->buf_off; 316 while (ctx->blockout && n > 0) 317 { 318 i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n); 319 if (i <= 0) 320 { 321 BIO_copy_next_retry(b); 322 if(!BIO_should_retry(b)) 323 ctx->cont= 0; 324 return(i); 325 } 326 ctx->buf_off+=i; 327 n-=i; 328 } 329 330 /* at this point all pending data has been written */ 331 ctx->blockout= 0; 332 if (ctx->buf_len == ctx->buf_off) 333 { 334 ctx->buf_len=OK_BLOCK_BLOCK; 335 ctx->buf_off=0; 336 } 337 338 if ((in == NULL) || (inl <= 0)) return(0); 339 340 n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ? 341 (int)(OK_BLOCK_SIZE+OK_BLOCK_BLOCK-ctx->buf_len) : inl; 342 343 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n); 344 ctx->buf_len+= n; 345 inl-=n; 346 in+=n; 347 348 if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) 349 { 350 if (!block_out(b)) 351 { 352 BIO_clear_retry_flags(b); 353 return 0; 354 } 355 } 356 }while(inl > 0); 357 358 BIO_clear_retry_flags(b); 359 BIO_copy_next_retry(b); 360 return(ret); 361 } 362 363 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr) 364 { 365 BIO_OK_CTX *ctx; 366 EVP_MD *md; 367 const EVP_MD **ppmd; 368 long ret=1; 369 int i; 370 371 ctx=b->ptr; 372 373 switch (cmd) 374 { 375 case BIO_CTRL_RESET: 376 ctx->buf_len=0; 377 ctx->buf_off=0; 378 ctx->buf_len_save=0; 379 ctx->buf_off_save=0; 380 ctx->cont=1; 381 ctx->finished=0; 382 ctx->blockout= 0; 383 ctx->sigio=1; 384 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 385 break; 386 case BIO_CTRL_EOF: /* More to read */ 387 if (ctx->cont <= 0) 388 ret=1; 389 else 390 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 391 break; 392 case BIO_CTRL_PENDING: /* More to read in buffer */ 393 case BIO_CTRL_WPENDING: /* More to read in buffer */ 394 ret=ctx->blockout ? ctx->buf_len-ctx->buf_off : 0; 395 if (ret <= 0) 396 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 397 break; 398 case BIO_CTRL_FLUSH: 399 /* do a final write */ 400 if(ctx->blockout == 0) 401 if (!block_out(b)) 402 return 0; 403 404 while (ctx->blockout) 405 { 406 i=ok_write(b,NULL,0); 407 if (i < 0) 408 { 409 ret=i; 410 break; 411 } 412 } 413 414 ctx->finished=1; 415 ctx->buf_off=ctx->buf_len=0; 416 ctx->cont=(int)ret; 417 418 /* Finally flush the underlying BIO */ 419 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 420 break; 421 case BIO_C_DO_STATE_MACHINE: 422 BIO_clear_retry_flags(b); 423 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 424 BIO_copy_next_retry(b); 425 break; 426 case BIO_CTRL_INFO: 427 ret=(long)ctx->cont; 428 break; 429 case BIO_C_SET_MD: 430 md=ptr; 431 if (!EVP_DigestInit_ex(&ctx->md, md, NULL)) 432 return 0; 433 b->init=1; 434 break; 435 case BIO_C_GET_MD: 436 if (b->init) 437 { 438 ppmd=ptr; 439 *ppmd=ctx->md.digest; 440 } 441 else 442 ret=0; 443 break; 444 default: 445 ret=BIO_ctrl(b->next_bio,cmd,num,ptr); 446 break; 447 } 448 return(ret); 449 } 450 451 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp) 452 { 453 long ret=1; 454 455 if (b->next_bio == NULL) return(0); 456 switch (cmd) 457 { 458 default: 459 ret=BIO_callback_ctrl(b->next_bio,cmd,fp); 460 break; 461 } 462 return(ret); 463 } 464 465 static void longswap(void *_ptr, size_t len) 466 { const union { long one; char little; } is_endian = {1}; 467 468 if (is_endian.little) { 469 size_t i; 470 unsigned char *p=_ptr,c; 471 472 for(i= 0;i < len;i+= 4) { 473 c=p[0],p[0]=p[3],p[3]=c; 474 c=p[1],p[1]=p[2],p[2]=c; 475 } 476 } 477 } 478 479 static int sig_out(BIO* b) 480 { 481 BIO_OK_CTX *ctx; 482 EVP_MD_CTX *md; 483 484 ctx=b->ptr; 485 md=&ctx->md; 486 487 if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return 1; 488 489 if (!EVP_DigestInit_ex(md, md->digest, NULL)) 490 goto berr; 491 /* FIXME: there's absolutely no guarantee this makes any sense at all, 492 * particularly now EVP_MD_CTX has been restructured. 493 */ 494 RAND_pseudo_bytes(md->md_data, md->digest->md_size); 495 memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size); 496 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size); 497 ctx->buf_len+= md->digest->md_size; 498 499 if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN))) 500 goto berr; 501 if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL)) 502 goto berr; 503 ctx->buf_len+= md->digest->md_size; 504 ctx->blockout= 1; 505 ctx->sigio= 0; 506 return 1; 507 berr: 508 BIO_clear_retry_flags(b); 509 return 0; 510 } 511 512 static int sig_in(BIO* b) 513 { 514 BIO_OK_CTX *ctx; 515 EVP_MD_CTX *md; 516 unsigned char tmp[EVP_MAX_MD_SIZE]; 517 int ret= 0; 518 519 ctx=b->ptr; 520 md=&ctx->md; 521 522 if((int)(ctx->buf_len-ctx->buf_off) < 2*md->digest->md_size) return 1; 523 524 if (!EVP_DigestInit_ex(md, md->digest, NULL)) 525 goto berr; 526 memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size); 527 longswap(md->md_data, md->digest->md_size); 528 ctx->buf_off+= md->digest->md_size; 529 530 if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN))) 531 goto berr; 532 if (!EVP_DigestFinal_ex(md, tmp, NULL)) 533 goto berr; 534 ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0; 535 ctx->buf_off+= md->digest->md_size; 536 if(ret == 1) 537 { 538 ctx->sigio= 0; 539 if(ctx->buf_len != ctx->buf_off) 540 { 541 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off); 542 } 543 ctx->buf_len-= ctx->buf_off; 544 ctx->buf_off= 0; 545 } 546 else 547 { 548 ctx->cont= 0; 549 } 550 return 1; 551 berr: 552 BIO_clear_retry_flags(b); 553 return 0; 554 } 555 556 static int block_out(BIO* b) 557 { 558 BIO_OK_CTX *ctx; 559 EVP_MD_CTX *md; 560 unsigned long tl; 561 562 ctx=b->ptr; 563 md=&ctx->md; 564 565 tl= ctx->buf_len- OK_BLOCK_BLOCK; 566 ctx->buf[0]=(unsigned char)(tl>>24); 567 ctx->buf[1]=(unsigned char)(tl>>16); 568 ctx->buf[2]=(unsigned char)(tl>>8); 569 ctx->buf[3]=(unsigned char)(tl); 570 if (!EVP_DigestUpdate(md, 571 (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl)) 572 goto berr; 573 if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL)) 574 goto berr; 575 ctx->buf_len+= md->digest->md_size; 576 ctx->blockout= 1; 577 return 1; 578 berr: 579 BIO_clear_retry_flags(b); 580 return 0; 581 } 582 583 static int block_in(BIO* b) 584 { 585 BIO_OK_CTX *ctx; 586 EVP_MD_CTX *md; 587 unsigned long tl= 0; 588 unsigned char tmp[EVP_MAX_MD_SIZE]; 589 590 ctx=b->ptr; 591 md=&ctx->md; 592 593 assert(sizeof(tl)>=OK_BLOCK_BLOCK); /* always true */ 594 tl =ctx->buf[0]; tl<<=8; 595 tl|=ctx->buf[1]; tl<<=8; 596 tl|=ctx->buf[2]; tl<<=8; 597 tl|=ctx->buf[3]; 598 599 if (ctx->buf_len < tl+ OK_BLOCK_BLOCK+ md->digest->md_size) return 1; 600 601 if (!EVP_DigestUpdate(md, 602 (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl)) 603 goto berr; 604 if (!EVP_DigestFinal_ex(md, tmp, NULL)) 605 goto berr; 606 if(memcmp(&(ctx->buf[tl+ OK_BLOCK_BLOCK]), tmp, md->digest->md_size) == 0) 607 { 608 /* there might be parts from next block lurking around ! */ 609 ctx->buf_off_save= tl+ OK_BLOCK_BLOCK+ md->digest->md_size; 610 ctx->buf_len_save= ctx->buf_len; 611 ctx->buf_off= OK_BLOCK_BLOCK; 612 ctx->buf_len= tl+ OK_BLOCK_BLOCK; 613 ctx->blockout= 1; 614 } 615 else 616 { 617 ctx->cont= 0; 618 } 619 return 1; 620 berr: 621 BIO_clear_retry_flags(b); 622 return 0; 623 } 624 625
