1 /* 2 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include <stdio.h> 11 #include "internal/cryptlib.h" 12 #include "internal/numbers.h" 13 #include <limits.h> 14 #include <openssl/asn1.h> 15 #include <openssl/bn.h> 16 #include "asn1_local.h" 17 18 ASN1_INTEGER *ASN1_INTEGER_dup(const ASN1_INTEGER *x) 19 { 20 return ASN1_STRING_dup(x); 21 } 22 23 int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y) 24 { 25 int neg, ret; 26 /* Compare signs */ 27 neg = x->type & V_ASN1_NEG; 28 if (neg != (y->type & V_ASN1_NEG)) { 29 if (neg) 30 return -1; 31 else 32 return 1; 33 } 34 35 ret = ASN1_STRING_cmp(x, y); 36 37 if (neg) 38 return -ret; 39 else 40 return ret; 41 } 42 43 /*- 44 * This converts a big endian buffer and sign into its content encoding. 45 * This is used for INTEGER and ENUMERATED types. 46 * The internal representation is an ASN1_STRING whose data is a big endian 47 * representation of the value, ignoring the sign. The sign is determined by 48 * the type: if type & V_ASN1_NEG is true it is negative, otherwise positive. 49 * 50 * Positive integers are no problem: they are almost the same as the DER 51 * encoding, except if the first byte is >= 0x80 we need to add a zero pad. 52 * 53 * Negative integers are a bit trickier... 54 * The DER representation of negative integers is in 2s complement form. 55 * The internal form is converted by complementing each octet and finally 56 * adding one to the result. This can be done less messily with a little trick. 57 * If the internal form has trailing zeroes then they will become FF by the 58 * complement and 0 by the add one (due to carry) so just copy as many trailing 59 * zeros to the destination as there are in the source. The carry will add one 60 * to the last none zero octet: so complement this octet and add one and finally 61 * complement any left over until you get to the start of the string. 62 * 63 * Padding is a little trickier too. If the first bytes is > 0x80 then we pad 64 * with 0xff. However if the first byte is 0x80 and one of the following bytes 65 * is non-zero we pad with 0xff. The reason for this distinction is that 0x80 66 * followed by optional zeros isn't padded. 67 */ 68 69 /* 70 * If |pad| is zero, the operation is effectively reduced to memcpy, 71 * and if |pad| is 0xff, then it performs two's complement, ~dst + 1. 72 * Note that in latter case sequence of zeros yields itself, and so 73 * does 0x80 followed by any number of zeros. These properties are 74 * used elsewhere below... 75 */ 76 static void twos_complement(unsigned char *dst, const unsigned char *src, 77 size_t len, unsigned char pad) 78 { 79 unsigned int carry = pad & 1; 80 81 /* Begin at the end of the encoding */ 82 dst += len; 83 src += len; 84 /* two's complement value: ~value + 1 */ 85 while (len-- != 0) { 86 *(--dst) = (unsigned char)(carry += *(--src) ^ pad); 87 carry >>= 8; 88 } 89 } 90 91 static size_t i2c_ibuf(const unsigned char *b, size_t blen, int neg, 92 unsigned char **pp) 93 { 94 unsigned int pad = 0; 95 size_t ret, i; 96 unsigned char *p, pb = 0; 97 98 if (b != NULL && blen) { 99 ret = blen; 100 i = b[0]; 101 if (!neg && (i > 127)) { 102 pad = 1; 103 pb = 0; 104 } else if (neg) { 105 pb = 0xFF; 106 if (i > 128) { 107 pad = 1; 108 } else if (i == 128) { 109 /* 110 * Special case [of minimal negative for given length]: 111 * if any other bytes non zero we pad, otherwise we don't. 112 */ 113 for (pad = 0, i = 1; i < blen; i++) 114 pad |= b[i]; 115 pb = pad != 0 ? 0xffU : 0; 116 pad = pb & 1; 117 } 118 } 119 ret += pad; 120 } else { 121 ret = 1; 122 blen = 0; /* reduce '(b == NULL || blen == 0)' to '(blen == 0)' */ 123 } 124 125 if (pp == NULL || (p = *pp) == NULL) 126 return ret; 127 128 /* 129 * This magically handles all corner cases, such as '(b == NULL || 130 * blen == 0)', non-negative value, "negative" zero, 0x80 followed 131 * by any number of zeros... 132 */ 133 *p = pb; 134 p += pad; /* yes, p[0] can be written twice, but it's little 135 * price to pay for eliminated branches */ 136 twos_complement(p, b, blen, pb); 137 138 *pp += ret; 139 return ret; 140 } 141 142 /* 143 * convert content octets into a big endian buffer. Returns the length 144 * of buffer or 0 on error: for malformed INTEGER. If output buffer is 145 * NULL just return length. 146 */ 147 148 static size_t c2i_ibuf(unsigned char *b, int *pneg, 149 const unsigned char *p, size_t plen) 150 { 151 int neg, pad; 152 /* Zero content length is illegal */ 153 if (plen == 0) { 154 ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_ZERO_CONTENT); 155 return 0; 156 } 157 neg = p[0] & 0x80; 158 if (pneg) 159 *pneg = neg; 160 /* Handle common case where length is 1 octet separately */ 161 if (plen == 1) { 162 if (b != NULL) { 163 if (neg) 164 b[0] = (p[0] ^ 0xFF) + 1; 165 else 166 b[0] = p[0]; 167 } 168 return 1; 169 } 170 171 pad = 0; 172 if (p[0] == 0) { 173 pad = 1; 174 } else if (p[0] == 0xFF) { 175 size_t i; 176 177 /* 178 * Special case [of "one less minimal negative" for given length]: 179 * if any other bytes non zero it was padded, otherwise not. 180 */ 181 for (pad = 0, i = 1; i < plen; i++) 182 pad |= p[i]; 183 pad = pad != 0 ? 1 : 0; 184 } 185 /* reject illegal padding: first two octets MSB can't match */ 186 if (pad && (neg == (p[1] & 0x80))) { 187 ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_PADDING); 188 return 0; 189 } 190 191 /* skip over pad */ 192 p += pad; 193 plen -= pad; 194 195 if (b != NULL) 196 twos_complement(b, p, plen, neg ? 0xffU : 0); 197 198 return plen; 199 } 200 201 int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp) 202 { 203 return i2c_ibuf(a->data, a->length, a->type & V_ASN1_NEG, pp); 204 } 205 206 /* Convert big endian buffer into uint64_t, return 0 on error */ 207 static int asn1_get_uint64(uint64_t *pr, const unsigned char *b, size_t blen) 208 { 209 size_t i; 210 uint64_t r; 211 212 if (blen > sizeof(*pr)) { 213 ASN1err(ASN1_F_ASN1_GET_UINT64, ASN1_R_TOO_LARGE); 214 return 0; 215 } 216 if (b == NULL) 217 return 0; 218 for (r = 0, i = 0; i < blen; i++) { 219 r <<= 8; 220 r |= b[i]; 221 } 222 *pr = r; 223 return 1; 224 } 225 226 /* 227 * Write uint64_t to big endian buffer and return offset to first 228 * written octet. In other words it returns offset in range from 0 229 * to 7, with 0 denoting 8 written octets and 7 - one. 230 */ 231 static size_t asn1_put_uint64(unsigned char b[sizeof(uint64_t)], uint64_t r) 232 { 233 size_t off = sizeof(uint64_t); 234 235 do { 236 b[--off] = (unsigned char)r; 237 } while (r >>= 8); 238 239 return off; 240 } 241 242 /* 243 * Absolute value of INT64_MIN: we can't just use -INT64_MIN as gcc produces 244 * overflow warnings. 245 */ 246 #define ABS_INT64_MIN ((uint64_t)INT64_MAX + (-(INT64_MIN + INT64_MAX))) 247 248 /* signed version of asn1_get_uint64 */ 249 static int asn1_get_int64(int64_t *pr, const unsigned char *b, size_t blen, 250 int neg) 251 { 252 uint64_t r; 253 if (asn1_get_uint64(&r, b, blen) == 0) 254 return 0; 255 if (neg) { 256 if (r <= INT64_MAX) { 257 /* Most significant bit is guaranteed to be clear, negation 258 * is guaranteed to be meaningful in platform-neutral sense. */ 259 *pr = -(int64_t)r; 260 } else if (r == ABS_INT64_MIN) { 261 /* This never happens if INT64_MAX == ABS_INT64_MIN, e.g. 262 * on ones'-complement system. */ 263 *pr = (int64_t)(0 - r); 264 } else { 265 ASN1err(ASN1_F_ASN1_GET_INT64, ASN1_R_TOO_SMALL); 266 return 0; 267 } 268 } else { 269 if (r <= INT64_MAX) { 270 *pr = (int64_t)r; 271 } else { 272 ASN1err(ASN1_F_ASN1_GET_INT64, ASN1_R_TOO_LARGE); 273 return 0; 274 } 275 } 276 return 1; 277 } 278 279 /* Convert ASN1 INTEGER content octets to ASN1_INTEGER structure */ 280 ASN1_INTEGER *c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp, 281 long len) 282 { 283 ASN1_INTEGER *ret = NULL; 284 size_t r; 285 int neg; 286 287 r = c2i_ibuf(NULL, NULL, *pp, len); 288 289 if (r == 0) 290 return NULL; 291 292 if ((a == NULL) || ((*a) == NULL)) { 293 ret = ASN1_INTEGER_new(); 294 if (ret == NULL) 295 return NULL; 296 ret->type = V_ASN1_INTEGER; 297 } else 298 ret = *a; 299 300 if (ASN1_STRING_set(ret, NULL, r) == 0) 301 goto err; 302 303 c2i_ibuf(ret->data, &neg, *pp, len); 304 305 if (neg) 306 ret->type |= V_ASN1_NEG; 307 308 *pp += len; 309 if (a != NULL) 310 (*a) = ret; 311 return ret; 312 err: 313 ASN1err(ASN1_F_C2I_ASN1_INTEGER, ERR_R_MALLOC_FAILURE); 314 if ((a == NULL) || (*a != ret)) 315 ASN1_INTEGER_free(ret); 316 return NULL; 317 } 318 319 static int asn1_string_get_int64(int64_t *pr, const ASN1_STRING *a, int itype) 320 { 321 if (a == NULL) { 322 ASN1err(ASN1_F_ASN1_STRING_GET_INT64, ERR_R_PASSED_NULL_PARAMETER); 323 return 0; 324 } 325 if ((a->type & ~V_ASN1_NEG) != itype) { 326 ASN1err(ASN1_F_ASN1_STRING_GET_INT64, ASN1_R_WRONG_INTEGER_TYPE); 327 return 0; 328 } 329 return asn1_get_int64(pr, a->data, a->length, a->type & V_ASN1_NEG); 330 } 331 332 static int asn1_string_set_int64(ASN1_STRING *a, int64_t r, int itype) 333 { 334 unsigned char tbuf[sizeof(r)]; 335 size_t off; 336 337 a->type = itype; 338 if (r < 0) { 339 /* Most obvious '-r' triggers undefined behaviour for most 340 * common INT64_MIN. Even though below '0 - (uint64_t)r' can 341 * appear two's-complement centric, it does produce correct/ 342 * expected result even on one's-complement. This is because 343 * cast to unsigned has to change bit pattern... */ 344 off = asn1_put_uint64(tbuf, 0 - (uint64_t)r); 345 a->type |= V_ASN1_NEG; 346 } else { 347 off = asn1_put_uint64(tbuf, r); 348 a->type &= ~V_ASN1_NEG; 349 } 350 return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off); 351 } 352 353 static int asn1_string_get_uint64(uint64_t *pr, const ASN1_STRING *a, 354 int itype) 355 { 356 if (a == NULL) { 357 ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ERR_R_PASSED_NULL_PARAMETER); 358 return 0; 359 } 360 if ((a->type & ~V_ASN1_NEG) != itype) { 361 ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ASN1_R_WRONG_INTEGER_TYPE); 362 return 0; 363 } 364 if (a->type & V_ASN1_NEG) { 365 ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ASN1_R_ILLEGAL_NEGATIVE_VALUE); 366 return 0; 367 } 368 return asn1_get_uint64(pr, a->data, a->length); 369 } 370 371 static int asn1_string_set_uint64(ASN1_STRING *a, uint64_t r, int itype) 372 { 373 unsigned char tbuf[sizeof(r)]; 374 size_t off; 375 376 a->type = itype; 377 off = asn1_put_uint64(tbuf, r); 378 return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off); 379 } 380 381 /* 382 * This is a version of d2i_ASN1_INTEGER that ignores the sign bit of ASN1 383 * integers: some broken software can encode a positive INTEGER with its MSB 384 * set as negative (it doesn't add a padding zero). 385 */ 386 387 ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp, 388 long length) 389 { 390 ASN1_INTEGER *ret = NULL; 391 const unsigned char *p; 392 unsigned char *s; 393 long len; 394 int inf, tag, xclass; 395 int i; 396 397 if ((a == NULL) || ((*a) == NULL)) { 398 if ((ret = ASN1_INTEGER_new()) == NULL) 399 return NULL; 400 ret->type = V_ASN1_INTEGER; 401 } else 402 ret = (*a); 403 404 p = *pp; 405 inf = ASN1_get_object(&p, &len, &tag, &xclass, length); 406 if (inf & 0x80) { 407 i = ASN1_R_BAD_OBJECT_HEADER; 408 goto err; 409 } 410 411 if (tag != V_ASN1_INTEGER) { 412 i = ASN1_R_EXPECTING_AN_INTEGER; 413 goto err; 414 } 415 416 /* 417 * We must OPENSSL_malloc stuff, even for 0 bytes otherwise it signifies 418 * a missing NULL parameter. 419 */ 420 s = OPENSSL_malloc((int)len + 1); 421 if (s == NULL) { 422 i = ERR_R_MALLOC_FAILURE; 423 goto err; 424 } 425 ret->type = V_ASN1_INTEGER; 426 if (len) { 427 if ((*p == 0) && (len != 1)) { 428 p++; 429 len--; 430 } 431 memcpy(s, p, (int)len); 432 p += len; 433 } 434 435 OPENSSL_free(ret->data); 436 ret->data = s; 437 ret->length = (int)len; 438 if (a != NULL) 439 (*a) = ret; 440 *pp = p; 441 return ret; 442 err: 443 ASN1err(ASN1_F_D2I_ASN1_UINTEGER, i); 444 if ((a == NULL) || (*a != ret)) 445 ASN1_INTEGER_free(ret); 446 return NULL; 447 } 448 449 static ASN1_STRING *bn_to_asn1_string(const BIGNUM *bn, ASN1_STRING *ai, 450 int atype) 451 { 452 ASN1_INTEGER *ret; 453 int len; 454 455 if (ai == NULL) { 456 ret = ASN1_STRING_type_new(atype); 457 } else { 458 ret = ai; 459 ret->type = atype; 460 } 461 462 if (ret == NULL) { 463 ASN1err(ASN1_F_BN_TO_ASN1_STRING, ERR_R_NESTED_ASN1_ERROR); 464 goto err; 465 } 466 467 if (BN_is_negative(bn) && !BN_is_zero(bn)) 468 ret->type |= V_ASN1_NEG_INTEGER; 469 470 len = BN_num_bytes(bn); 471 472 if (len == 0) 473 len = 1; 474 475 if (ASN1_STRING_set(ret, NULL, len) == 0) { 476 ASN1err(ASN1_F_BN_TO_ASN1_STRING, ERR_R_MALLOC_FAILURE); 477 goto err; 478 } 479 480 /* Correct zero case */ 481 if (BN_is_zero(bn)) 482 ret->data[0] = 0; 483 else 484 len = BN_bn2bin(bn, ret->data); 485 ret->length = len; 486 return ret; 487 err: 488 if (ret != ai) 489 ASN1_INTEGER_free(ret); 490 return NULL; 491 } 492 493 static BIGNUM *asn1_string_to_bn(const ASN1_INTEGER *ai, BIGNUM *bn, 494 int itype) 495 { 496 BIGNUM *ret; 497 498 if ((ai->type & ~V_ASN1_NEG) != itype) { 499 ASN1err(ASN1_F_ASN1_STRING_TO_BN, ASN1_R_WRONG_INTEGER_TYPE); 500 return NULL; 501 } 502 503 ret = BN_bin2bn(ai->data, ai->length, bn); 504 if (ret == NULL) { 505 ASN1err(ASN1_F_ASN1_STRING_TO_BN, ASN1_R_BN_LIB); 506 return NULL; 507 } 508 if (ai->type & V_ASN1_NEG) 509 BN_set_negative(ret, 1); 510 return ret; 511 } 512 513 int ASN1_INTEGER_get_int64(int64_t *pr, const ASN1_INTEGER *a) 514 { 515 return asn1_string_get_int64(pr, a, V_ASN1_INTEGER); 516 } 517 518 int ASN1_INTEGER_set_int64(ASN1_INTEGER *a, int64_t r) 519 { 520 return asn1_string_set_int64(a, r, V_ASN1_INTEGER); 521 } 522 523 int ASN1_INTEGER_get_uint64(uint64_t *pr, const ASN1_INTEGER *a) 524 { 525 return asn1_string_get_uint64(pr, a, V_ASN1_INTEGER); 526 } 527 528 int ASN1_INTEGER_set_uint64(ASN1_INTEGER *a, uint64_t r) 529 { 530 return asn1_string_set_uint64(a, r, V_ASN1_INTEGER); 531 } 532 533 int ASN1_INTEGER_set(ASN1_INTEGER *a, long v) 534 { 535 return ASN1_INTEGER_set_int64(a, v); 536 } 537 538 long ASN1_INTEGER_get(const ASN1_INTEGER *a) 539 { 540 int i; 541 int64_t r; 542 if (a == NULL) 543 return 0; 544 i = ASN1_INTEGER_get_int64(&r, a); 545 if (i == 0) 546 return -1; 547 if (r > LONG_MAX || r < LONG_MIN) 548 return -1; 549 return (long)r; 550 } 551 552 ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai) 553 { 554 return bn_to_asn1_string(bn, ai, V_ASN1_INTEGER); 555 } 556 557 BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn) 558 { 559 return asn1_string_to_bn(ai, bn, V_ASN1_INTEGER); 560 } 561 562 int ASN1_ENUMERATED_get_int64(int64_t *pr, const ASN1_ENUMERATED *a) 563 { 564 return asn1_string_get_int64(pr, a, V_ASN1_ENUMERATED); 565 } 566 567 int ASN1_ENUMERATED_set_int64(ASN1_ENUMERATED *a, int64_t r) 568 { 569 return asn1_string_set_int64(a, r, V_ASN1_ENUMERATED); 570 } 571 572 int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v) 573 { 574 return ASN1_ENUMERATED_set_int64(a, v); 575 } 576 577 long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a) 578 { 579 int i; 580 int64_t r; 581 if (a == NULL) 582 return 0; 583 if ((a->type & ~V_ASN1_NEG) != V_ASN1_ENUMERATED) 584 return -1; 585 if (a->length > (int)sizeof(long)) 586 return 0xffffffffL; 587 i = ASN1_ENUMERATED_get_int64(&r, a); 588 if (i == 0) 589 return -1; 590 if (r > LONG_MAX || r < LONG_MIN) 591 return -1; 592 return (long)r; 593 } 594 595 ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai) 596 { 597 return bn_to_asn1_string(bn, ai, V_ASN1_ENUMERATED); 598 } 599 600 BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn) 601 { 602 return asn1_string_to_bn(ai, bn, V_ASN1_ENUMERATED); 603 } 604 605 /* Internal functions used by x_int64.c */ 606 int c2i_uint64_int(uint64_t *ret, int *neg, const unsigned char **pp, long len) 607 { 608 unsigned char buf[sizeof(uint64_t)]; 609 size_t buflen; 610 611 buflen = c2i_ibuf(NULL, NULL, *pp, len); 612 if (buflen == 0) 613 return 0; 614 if (buflen > sizeof(uint64_t)) { 615 ASN1err(ASN1_F_C2I_UINT64_INT, ASN1_R_TOO_LARGE); 616 return 0; 617 } 618 (void)c2i_ibuf(buf, neg, *pp, len); 619 return asn1_get_uint64(ret, buf, buflen); 620 } 621 622 int i2c_uint64_int(unsigned char *p, uint64_t r, int neg) 623 { 624 unsigned char buf[sizeof(uint64_t)]; 625 size_t off; 626 627 off = asn1_put_uint64(buf, r); 628 return i2c_ibuf(buf + off, sizeof(buf) - off, neg, &p); 629 } 630 631