1 /* 2 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (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 if (len != 0) { 83 /* 84 * if len == 0 then src/dst could be NULL, and this would be undefined 85 * behaviour. 86 */ 87 dst += len; 88 src += len; 89 } 90 /* two's complement value: ~value + 1 */ 91 while (len-- != 0) { 92 *(--dst) = (unsigned char)(carry += *(--src) ^ pad); 93 carry >>= 8; 94 } 95 } 96 97 static size_t i2c_ibuf(const unsigned char *b, size_t blen, int neg, 98 unsigned char **pp) 99 { 100 unsigned int pad = 0; 101 size_t ret, i; 102 unsigned char *p, pb = 0; 103 104 if (b != NULL && blen) { 105 ret = blen; 106 i = b[0]; 107 if (!neg && (i > 127)) { 108 pad = 1; 109 pb = 0; 110 } else if (neg) { 111 pb = 0xFF; 112 if (i > 128) { 113 pad = 1; 114 } else if (i == 128) { 115 /* 116 * Special case [of minimal negative for given length]: 117 * if any other bytes non zero we pad, otherwise we don't. 118 */ 119 for (pad = 0, i = 1; i < blen; i++) 120 pad |= b[i]; 121 pb = pad != 0 ? 0xffU : 0; 122 pad = pb & 1; 123 } 124 } 125 ret += pad; 126 } else { 127 ret = 1; 128 blen = 0; /* reduce '(b == NULL || blen == 0)' to '(blen == 0)' */ 129 } 130 131 if (pp == NULL || (p = *pp) == NULL) 132 return ret; 133 134 /* 135 * This magically handles all corner cases, such as '(b == NULL || 136 * blen == 0)', non-negative value, "negative" zero, 0x80 followed 137 * by any number of zeros... 138 */ 139 *p = pb; 140 p += pad; /* yes, p[0] can be written twice, but it's little 141 * price to pay for eliminated branches */ 142 twos_complement(p, b, blen, pb); 143 144 *pp += ret; 145 return ret; 146 } 147 148 /* 149 * convert content octets into a big endian buffer. Returns the length 150 * of buffer or 0 on error: for malformed INTEGER. If output buffer is 151 * NULL just return length. 152 */ 153 154 static size_t c2i_ibuf(unsigned char *b, int *pneg, 155 const unsigned char *p, size_t plen) 156 { 157 int neg, pad; 158 /* Zero content length is illegal */ 159 if (plen == 0) { 160 ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_ZERO_CONTENT); 161 return 0; 162 } 163 neg = p[0] & 0x80; 164 if (pneg) 165 *pneg = neg; 166 /* Handle common case where length is 1 octet separately */ 167 if (plen == 1) { 168 if (b != NULL) { 169 if (neg) 170 b[0] = (p[0] ^ 0xFF) + 1; 171 else 172 b[0] = p[0]; 173 } 174 return 1; 175 } 176 177 pad = 0; 178 if (p[0] == 0) { 179 pad = 1; 180 } else if (p[0] == 0xFF) { 181 size_t i; 182 183 /* 184 * Special case [of "one less minimal negative" for given length]: 185 * if any other bytes non zero it was padded, otherwise not. 186 */ 187 for (pad = 0, i = 1; i < plen; i++) 188 pad |= p[i]; 189 pad = pad != 0 ? 1 : 0; 190 } 191 /* reject illegal padding: first two octets MSB can't match */ 192 if (pad && (neg == (p[1] & 0x80))) { 193 ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_PADDING); 194 return 0; 195 } 196 197 /* skip over pad */ 198 p += pad; 199 plen -= pad; 200 201 if (b != NULL) 202 twos_complement(b, p, plen, neg ? 0xffU : 0); 203 204 return plen; 205 } 206 207 int ossl_i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp) 208 { 209 return i2c_ibuf(a->data, a->length, a->type & V_ASN1_NEG, pp); 210 } 211 212 /* Convert big endian buffer into uint64_t, return 0 on error */ 213 static int asn1_get_uint64(uint64_t *pr, const unsigned char *b, size_t blen) 214 { 215 size_t i; 216 uint64_t r; 217 218 if (blen > sizeof(*pr)) { 219 ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE); 220 return 0; 221 } 222 if (b == NULL) 223 return 0; 224 for (r = 0, i = 0; i < blen; i++) { 225 r <<= 8; 226 r |= b[i]; 227 } 228 *pr = r; 229 return 1; 230 } 231 232 /* 233 * Write uint64_t to big endian buffer and return offset to first 234 * written octet. In other words it returns offset in range from 0 235 * to 7, with 0 denoting 8 written octets and 7 - one. 236 */ 237 static size_t asn1_put_uint64(unsigned char b[sizeof(uint64_t)], uint64_t r) 238 { 239 size_t off = sizeof(uint64_t); 240 241 do { 242 b[--off] = (unsigned char)r; 243 } while (r >>= 8); 244 245 return off; 246 } 247 248 /* 249 * Absolute value of INT64_MIN: we can't just use -INT64_MIN as gcc produces 250 * overflow warnings. 251 */ 252 #define ABS_INT64_MIN ((uint64_t)INT64_MAX + (-(INT64_MIN + INT64_MAX))) 253 254 /* signed version of asn1_get_uint64 */ 255 static int asn1_get_int64(int64_t *pr, const unsigned char *b, size_t blen, 256 int neg) 257 { 258 uint64_t r; 259 if (asn1_get_uint64(&r, b, blen) == 0) 260 return 0; 261 if (neg) { 262 if (r <= INT64_MAX) { 263 /* Most significant bit is guaranteed to be clear, negation 264 * is guaranteed to be meaningful in platform-neutral sense. */ 265 *pr = -(int64_t)r; 266 } else if (r == ABS_INT64_MIN) { 267 /* This never happens if INT64_MAX == ABS_INT64_MIN, e.g. 268 * on ones'-complement system. */ 269 *pr = (int64_t)(0 - r); 270 } else { 271 ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_SMALL); 272 return 0; 273 } 274 } else { 275 if (r <= INT64_MAX) { 276 *pr = (int64_t)r; 277 } else { 278 ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE); 279 return 0; 280 } 281 } 282 return 1; 283 } 284 285 /* Convert ASN1 INTEGER content octets to ASN1_INTEGER structure */ 286 ASN1_INTEGER *ossl_c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp, 287 long len) 288 { 289 ASN1_INTEGER *ret = NULL; 290 size_t r; 291 int neg; 292 293 r = c2i_ibuf(NULL, NULL, *pp, len); 294 295 if (r == 0) 296 return NULL; 297 298 if ((a == NULL) || ((*a) == NULL)) { 299 ret = ASN1_INTEGER_new(); 300 if (ret == NULL) 301 return NULL; 302 ret->type = V_ASN1_INTEGER; 303 } else 304 ret = *a; 305 306 if (ASN1_STRING_set(ret, NULL, r) == 0) 307 goto err; 308 309 c2i_ibuf(ret->data, &neg, *pp, len); 310 311 if (neg != 0) 312 ret->type |= V_ASN1_NEG; 313 else 314 ret->type &= ~V_ASN1_NEG; 315 316 *pp += len; 317 if (a != NULL) 318 (*a) = ret; 319 return ret; 320 err: 321 ERR_raise(ERR_LIB_ASN1, ERR_R_MALLOC_FAILURE); 322 if (a == NULL || *a != ret) 323 ASN1_INTEGER_free(ret); 324 return NULL; 325 } 326 327 static int asn1_string_get_int64(int64_t *pr, const ASN1_STRING *a, int itype) 328 { 329 if (a == NULL) { 330 ERR_raise(ERR_LIB_ASN1, ERR_R_PASSED_NULL_PARAMETER); 331 return 0; 332 } 333 if ((a->type & ~V_ASN1_NEG) != itype) { 334 ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE); 335 return 0; 336 } 337 return asn1_get_int64(pr, a->data, a->length, a->type & V_ASN1_NEG); 338 } 339 340 static int asn1_string_set_int64(ASN1_STRING *a, int64_t r, int itype) 341 { 342 unsigned char tbuf[sizeof(r)]; 343 size_t off; 344 345 a->type = itype; 346 if (r < 0) { 347 /* Most obvious '-r' triggers undefined behaviour for most 348 * common INT64_MIN. Even though below '0 - (uint64_t)r' can 349 * appear two's-complement centric, it does produce correct/ 350 * expected result even on one's-complement. This is because 351 * cast to unsigned has to change bit pattern... */ 352 off = asn1_put_uint64(tbuf, 0 - (uint64_t)r); 353 a->type |= V_ASN1_NEG; 354 } else { 355 off = asn1_put_uint64(tbuf, r); 356 a->type &= ~V_ASN1_NEG; 357 } 358 return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off); 359 } 360 361 static int asn1_string_get_uint64(uint64_t *pr, const ASN1_STRING *a, 362 int itype) 363 { 364 if (a == NULL) { 365 ERR_raise(ERR_LIB_ASN1, ERR_R_PASSED_NULL_PARAMETER); 366 return 0; 367 } 368 if ((a->type & ~V_ASN1_NEG) != itype) { 369 ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE); 370 return 0; 371 } 372 if (a->type & V_ASN1_NEG) { 373 ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_NEGATIVE_VALUE); 374 return 0; 375 } 376 return asn1_get_uint64(pr, a->data, a->length); 377 } 378 379 static int asn1_string_set_uint64(ASN1_STRING *a, uint64_t r, int itype) 380 { 381 unsigned char tbuf[sizeof(r)]; 382 size_t off; 383 384 a->type = itype; 385 off = asn1_put_uint64(tbuf, r); 386 return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off); 387 } 388 389 /* 390 * This is a version of d2i_ASN1_INTEGER that ignores the sign bit of ASN1 391 * integers: some broken software can encode a positive INTEGER with its MSB 392 * set as negative (it doesn't add a padding zero). 393 */ 394 395 ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp, 396 long length) 397 { 398 ASN1_INTEGER *ret = NULL; 399 const unsigned char *p; 400 unsigned char *s; 401 long len = 0; 402 int inf, tag, xclass; 403 int i; 404 405 if ((a == NULL) || ((*a) == NULL)) { 406 if ((ret = ASN1_INTEGER_new()) == NULL) 407 return NULL; 408 ret->type = V_ASN1_INTEGER; 409 } else 410 ret = (*a); 411 412 p = *pp; 413 inf = ASN1_get_object(&p, &len, &tag, &xclass, length); 414 if (inf & 0x80) { 415 i = ASN1_R_BAD_OBJECT_HEADER; 416 goto err; 417 } 418 419 if (tag != V_ASN1_INTEGER) { 420 i = ASN1_R_EXPECTING_AN_INTEGER; 421 goto err; 422 } 423 424 if (len < 0) { 425 i = ASN1_R_ILLEGAL_NEGATIVE_VALUE; 426 goto err; 427 } 428 /* 429 * We must OPENSSL_malloc stuff, even for 0 bytes otherwise it signifies 430 * a missing NULL parameter. 431 */ 432 s = OPENSSL_malloc((int)len + 1); 433 if (s == NULL) { 434 i = ERR_R_MALLOC_FAILURE; 435 goto err; 436 } 437 ret->type = V_ASN1_INTEGER; 438 if (len) { 439 if ((*p == 0) && (len != 1)) { 440 p++; 441 len--; 442 } 443 memcpy(s, p, (int)len); 444 p += len; 445 } 446 447 OPENSSL_free(ret->data); 448 ret->data = s; 449 ret->length = (int)len; 450 if (a != NULL) 451 (*a) = ret; 452 *pp = p; 453 return ret; 454 err: 455 ERR_raise(ERR_LIB_ASN1, i); 456 if ((a == NULL) || (*a != ret)) 457 ASN1_INTEGER_free(ret); 458 return NULL; 459 } 460 461 static ASN1_STRING *bn_to_asn1_string(const BIGNUM *bn, ASN1_STRING *ai, 462 int atype) 463 { 464 ASN1_INTEGER *ret; 465 int len; 466 467 if (ai == NULL) { 468 ret = ASN1_STRING_type_new(atype); 469 } else { 470 ret = ai; 471 ret->type = atype; 472 } 473 474 if (ret == NULL) { 475 ERR_raise(ERR_LIB_ASN1, ERR_R_NESTED_ASN1_ERROR); 476 goto err; 477 } 478 479 if (BN_is_negative(bn) && !BN_is_zero(bn)) 480 ret->type |= V_ASN1_NEG_INTEGER; 481 482 len = BN_num_bytes(bn); 483 484 if (len == 0) 485 len = 1; 486 487 if (ASN1_STRING_set(ret, NULL, len) == 0) { 488 ERR_raise(ERR_LIB_ASN1, ERR_R_MALLOC_FAILURE); 489 goto err; 490 } 491 492 /* Correct zero case */ 493 if (BN_is_zero(bn)) 494 ret->data[0] = 0; 495 else 496 len = BN_bn2bin(bn, ret->data); 497 ret->length = len; 498 return ret; 499 err: 500 if (ret != ai) 501 ASN1_INTEGER_free(ret); 502 return NULL; 503 } 504 505 static BIGNUM *asn1_string_to_bn(const ASN1_INTEGER *ai, BIGNUM *bn, 506 int itype) 507 { 508 BIGNUM *ret; 509 510 if ((ai->type & ~V_ASN1_NEG) != itype) { 511 ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE); 512 return NULL; 513 } 514 515 ret = BN_bin2bn(ai->data, ai->length, bn); 516 if (ret == NULL) { 517 ERR_raise(ERR_LIB_ASN1, ASN1_R_BN_LIB); 518 return NULL; 519 } 520 if (ai->type & V_ASN1_NEG) 521 BN_set_negative(ret, 1); 522 return ret; 523 } 524 525 int ASN1_INTEGER_get_int64(int64_t *pr, const ASN1_INTEGER *a) 526 { 527 return asn1_string_get_int64(pr, a, V_ASN1_INTEGER); 528 } 529 530 int ASN1_INTEGER_set_int64(ASN1_INTEGER *a, int64_t r) 531 { 532 return asn1_string_set_int64(a, r, V_ASN1_INTEGER); 533 } 534 535 int ASN1_INTEGER_get_uint64(uint64_t *pr, const ASN1_INTEGER *a) 536 { 537 return asn1_string_get_uint64(pr, a, V_ASN1_INTEGER); 538 } 539 540 int ASN1_INTEGER_set_uint64(ASN1_INTEGER *a, uint64_t r) 541 { 542 return asn1_string_set_uint64(a, r, V_ASN1_INTEGER); 543 } 544 545 int ASN1_INTEGER_set(ASN1_INTEGER *a, long v) 546 { 547 return ASN1_INTEGER_set_int64(a, v); 548 } 549 550 long ASN1_INTEGER_get(const ASN1_INTEGER *a) 551 { 552 int i; 553 int64_t r; 554 if (a == NULL) 555 return 0; 556 i = ASN1_INTEGER_get_int64(&r, a); 557 if (i == 0) 558 return -1; 559 if (r > LONG_MAX || r < LONG_MIN) 560 return -1; 561 return (long)r; 562 } 563 564 ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai) 565 { 566 return bn_to_asn1_string(bn, ai, V_ASN1_INTEGER); 567 } 568 569 BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn) 570 { 571 return asn1_string_to_bn(ai, bn, V_ASN1_INTEGER); 572 } 573 574 int ASN1_ENUMERATED_get_int64(int64_t *pr, const ASN1_ENUMERATED *a) 575 { 576 return asn1_string_get_int64(pr, a, V_ASN1_ENUMERATED); 577 } 578 579 int ASN1_ENUMERATED_set_int64(ASN1_ENUMERATED *a, int64_t r) 580 { 581 return asn1_string_set_int64(a, r, V_ASN1_ENUMERATED); 582 } 583 584 int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v) 585 { 586 return ASN1_ENUMERATED_set_int64(a, v); 587 } 588 589 long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a) 590 { 591 int i; 592 int64_t r; 593 if (a == NULL) 594 return 0; 595 if ((a->type & ~V_ASN1_NEG) != V_ASN1_ENUMERATED) 596 return -1; 597 if (a->length > (int)sizeof(long)) 598 return 0xffffffffL; 599 i = ASN1_ENUMERATED_get_int64(&r, a); 600 if (i == 0) 601 return -1; 602 if (r > LONG_MAX || r < LONG_MIN) 603 return -1; 604 return (long)r; 605 } 606 607 ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai) 608 { 609 return bn_to_asn1_string(bn, ai, V_ASN1_ENUMERATED); 610 } 611 612 BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn) 613 { 614 return asn1_string_to_bn(ai, bn, V_ASN1_ENUMERATED); 615 } 616 617 /* Internal functions used by x_int64.c */ 618 int ossl_c2i_uint64_int(uint64_t *ret, int *neg, 619 const unsigned char **pp, long len) 620 { 621 unsigned char buf[sizeof(uint64_t)]; 622 size_t buflen; 623 624 buflen = c2i_ibuf(NULL, NULL, *pp, len); 625 if (buflen == 0) 626 return 0; 627 if (buflen > sizeof(uint64_t)) { 628 ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE); 629 return 0; 630 } 631 (void)c2i_ibuf(buf, neg, *pp, len); 632 return asn1_get_uint64(ret, buf, buflen); 633 } 634 635 int ossl_i2c_uint64_int(unsigned char *p, uint64_t r, int neg) 636 { 637 unsigned char buf[sizeof(uint64_t)]; 638 size_t off; 639 640 off = asn1_put_uint64(buf, r); 641 return i2c_ibuf(buf + off, sizeof(buf) - off, neg, &p); 642 } 643 644