lib/asn1/der_get.c

   1 /*
   2  * Copyright (c) 1997 - 2007 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "der_locl.h"
  35
  36 /*
  37  * All decoding functions take a pointer `p' to first position in
  38  * which to read, from the left, `len' which means the maximum number
  39  * of characters we are able to read, `ret' were the value will be
  40  * returned and `size' where the number of used bytes is stored.
  41  * Either 0 or an error code is returned.
  42  */
  43
  44 int
  45 der_get_unsigned (const unsigned char *p, size_t len,
  46                   unsigned *ret, size_t *size)
  47 {
  48     unsigned val = 0;
  49     size_t oldlen = len;
  50
  51     if (len == sizeof(unsigned) + 1 && p[0] == 0)
  52         ;
  53     else if (len > sizeof(unsigned))
  54         return ASN1_OVERRUN;
  55
  56     while (len--)
  57         val = val * 256 + *p++;
  58     *ret = val;
  59     if(size) *size = oldlen;
  60     return 0;
  61 }
  62
  63 int
  64 der_get_integer (const unsigned char *p, size_t len,
  65                  int *ret, size_t *size)
  66 {
  67     int val = 0;
  68     size_t oldlen = len;
  69
  70     if (len > sizeof(int))
  71         return ASN1_OVERRUN;
  72
  73     if (len > 0) {
  74         val = (signed char)*p++;
  75         while (--len)
  76             val = val * 256 + *p++;
  77     }
  78     *ret = val;
  79     if(size) *size = oldlen;
  80     return 0;
  81 }
  82
  83 int
  84 der_get_length (const unsigned char *p, size_t len,
  85                 size_t *val, size_t *size)
  86 {
  87     size_t v;
  88
  89     if (len <= 0)
  90         return ASN1_OVERRUN;
  91     --len;
  92     v = *p++;
  93     if (v < 128) {
  94         *val = v;
  95         if(size) *size = 1;
  96     } else {
  97         int e;
  98         size_t l;
  99         unsigned tmp;
 100
 101         if(v == 0x80){
 102             *val = ASN1_INDEFINITE;
 103             if(size) *size = 1;
 104             return 0;
 105         }
 106         v &= 0x7F;
 107         if (len < v)
 108             return ASN1_OVERRUN;
 109         e = der_get_unsigned (p, v, &tmp, &l);
 110         if(e) return e;
 111         *val = tmp;
 112         if(size) *size = l + 1;
 113     }
 114     return 0;
 115 }
 116
 117 int
 118 der_get_boolean(const unsigned char *p, size_t len, int *data, size_t *size)
 119 {
 120     if(len < 1)
 121         return ASN1_OVERRUN;
 122     if(*p != 0)
 123         *data = 1;
 124     else
 125         *data = 0;
 126     *size = 1;
 127     return 0;
 128 }
 129
 130 int
 131 der_get_general_string (const unsigned char *p, size_t len,
 132                         heim_general_string *str, size_t *size)
 133 {
 134     const unsigned char *p1;
 135     char *s;
 136
 137     p1 = memchr(p, 0, len);
 138     if (p1 != NULL) {
 139         /*
 140          * Allow trailing NULs. We allow this since MIT Kerberos sends
 141          * an strings in the NEED_PREAUTH case that includes a
 142          * trailing NUL.
 143          */
 144         while (p1 - p < len && *p1 == '\0')
 145             p1++;
 146        if (p1 - p != len)
 147             return ASN1_BAD_CHARACTER;
 148     }
 149     if (len > len + 1)
 150         return ASN1_BAD_LENGTH;
 151
 152     s = malloc (len + 1);
 153     if (s == NULL)
 154         return ENOMEM;
 155     memcpy (s, p, len);
 156     s[len] = '\0';
 157     *str = s;
 158     if(size) *size = len;
 159     return 0;
 160 }
 161
 162 int
 163 der_get_utf8string (const unsigned char *p, size_t len,
 164                     heim_utf8_string *str, size_t *size)
 165 {
 166     return der_get_general_string(p, len, str, size);
 167 }
 168
 169 int
 170 der_get_printable_string (const unsigned char *p, size_t len,
 171                           heim_printable_string *str, size_t *size)
 172 {
 173     return der_get_general_string(p, len, str, size);
 174 }
 175
 176 int
 177 der_get_ia5_string (const unsigned char *p, size_t len,
 178                     heim_ia5_string *str, size_t *size)
 179 {
 180     return der_get_general_string(p, len, str, size);
 181 }
 182
 183 int
 184 der_get_bmp_string (const unsigned char *p, size_t len,
 185                     heim_bmp_string *data, size_t *size)
 186 {
 187     size_t i;
 188
 189     if (len & 1)
 190         return ASN1_BAD_FORMAT;
 191     data->length = len / 2;
 192     if (data->length > UINT_MAX/sizeof(data->data[0]))
 193         return ERANGE;
 194     data->data = malloc(data->length * sizeof(data->data[0]));
 195     if (data->data == NULL && data->length != 0)
 196         return ENOMEM;
 197
 198     for (i = 0; i < data->length; i++) {
 199         data->data[i] = (p[0] << 8) | p[1];
 200         p += 2;
 201         /* check for NUL in the middle of the string */
 202         if (data->data[i] == 0 && i != (data->length - 1)) {
 203             free(data->data);
 204             data->data = NULL;
 205             data->length = 0;
 206             return ASN1_BAD_CHARACTER;
 207         }
 208     }
 209     if (size) *size = len;
 210
 211     return 0;
 212 }
 213
 214 int
 215 der_get_universal_string (const unsigned char *p, size_t len,
 216                           heim_universal_string *data, size_t *size)
 217 {
 218     size_t i;
 219
 220     if (len & 3)
 221         return ASN1_BAD_FORMAT;
 222     data->length = len / 4;
 223     if (data->length > UINT_MAX/sizeof(data->data[0]))
 224         return ERANGE;
 225     data->data = malloc(data->length * sizeof(data->data[0]));
 226     if (data->data == NULL && data->length != 0)
 227         return ENOMEM;
 228
 229     for (i = 0; i < data->length; i++) {
 230         data->data[i] = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
 231         p += 4;
 232         /* check for NUL in the middle of the string */
 233         if (data->data[i] == 0 && i != (data->length - 1)) {
 234             free(data->data);
 235             data->data = NULL;
 236             data->length = 0;
 237             return ASN1_BAD_CHARACTER;
 238         }
 239     }
 240     if (size) *size = len;
 241     return 0;
 242 }
 243
 244 int
 245 der_get_visible_string (const unsigned char *p, size_t len,
 246                         heim_visible_string *str, size_t *size)
 247 {
 248     return der_get_general_string(p, len, str, size);
 249 }
 250
 251 int
 252 der_get_octet_string (const unsigned char *p, size_t len,
 253                       heim_octet_string *data, size_t *size)
 254 {
 255     data->length = len;
 256     data->data = malloc(len);
 257     if (data->data == NULL && data->length != 0)
 258         return ENOMEM;
 259     memcpy (data->data, p, len);
 260     if(size) *size = len;
 261     return 0;
 262 }
 263
 264 int
 265 der_get_octet_string_ber (const unsigned char *p, size_t len,
 266                           heim_octet_string *data, size_t *size)
 267 {
 268     int e;
 269     Der_type type;
 270     Der_class class;
 271     unsigned int tag, depth = 0;
 272     size_t l, datalen, oldlen = len;
 273
 274     data->length = 0;
 275     data->data = NULL;
 276
 277     while (len) {
 278         e = der_get_tag (p, len, &class, &type, &tag, &l);
 279         if (e) goto out;
 280         if (class != ASN1_C_UNIV) {
 281             e = ASN1_BAD_ID;
 282             goto out;
 283         }
 284         if (type == PRIM && tag == UT_EndOfContent) {
 285             if (depth == 0)
 286                 break;
 287             depth--;
 288         }
 289         if (tag != UT_OctetString) {
 290             e = ASN1_BAD_ID;
 291             goto out;
 292         }
 293
 294         p += l;
 295         len -= l;
 296         e = der_get_length (p, len, &datalen, &l);
 297         if (e) goto out;
 298         p += l;
 299         len -= l;
 300
 301         if (datalen > len)
 302             return ASN1_OVERRUN;
 303
 304         if (type == PRIM) {
 305             void *ptr;
 306
 307             ptr = realloc(data->data, data->length + datalen);
 308             if (ptr == NULL && data->length + datalen != 0) {
 309                 e = ENOMEM;
 310                 goto out;
 311             }
 312             data->data = ptr;
 313             memcpy(((unsigned char *)data->data) + data->length, p, datalen);
 314             data->length += datalen;
 315         } else
 316             depth++;
 317
 318         p += datalen;
 319         len -= datalen;
 320     }
 321     if (depth != 0)
 322         return ASN1_INDEF_OVERRUN;
 323     if(size) *size = oldlen - len;
 324     return 0;
 325  out:
 326     free(data->data);
 327     data->data = NULL;
 328     data->length = 0;
 329     return e;
 330 }
 331
 332
 333 int
 334 der_get_heim_integer (const unsigned char *p, size_t len,
 335                       heim_integer *data, size_t *size)
 336 {
 337     data->length = 0;
 338     data->negative = 0;
 339     data->data = NULL;
 340
 341     if (len == 0) {
 342         if (size)
 343             *size = 0;
 344         return 0;
 345     }
 346     if (p[0] & 0x80) {
 347         unsigned char *q;
 348         int carry = 1;
 349         data->negative = 1;
 350
 351         data->length = len;
 352
 353         if (p[0] == 0xff) {
 354             p++;
 355             data->length--;
 356         }
 357         if (data->length) {
 358             data->data = malloc(data->length);
 359             if (data->data == NULL) {
 360                 data->length = 0;
 361                 if (size)
 362                     *size = 0;
 363                 return ENOMEM;
 364             }
 365             q = &((unsigned char*)data->data)[data->length - 1];
 366             p += data->length - 1;
 367             while (q >= (unsigned char*)data->data) {
 368                 *q = *p ^ 0xff;
 369                 if (carry)
 370                     carry = !++*q;
 371                 p--;
 372                 q--;
 373             }
 374         }
 375     } else {
 376         data->negative = 0;
 377         data->length = len;
 378
 379         if (p[0] == 0) {
 380             p++;
 381             data->length--;
 382         }
 383         data->data = malloc(data->length);
 384         if (data->data == NULL && data->length != 0) {
 385             data->length = 0;
 386             if (size)
 387                 *size = 0;
 388             return ENOMEM;
 389         }
 390         memcpy(data->data, p, data->length);
 391     }
 392     if (size)
 393         *size = len;
 394     return 0;
 395 }
 396
 397 static int
 398 generalizedtime2time (const char *s, time_t *t)
 399 {
 400     struct tm tm;
 401
 402     memset(&tm, 0, sizeof(tm));
 403     if (sscanf (s, "%04d%02d%02d%02d%02d%02dZ",
 404                 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 405                 &tm.tm_min, &tm.tm_sec) != 6) {
 406         if (sscanf (s, "%02d%02d%02d%02d%02d%02dZ",
 407                     &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 408                     &tm.tm_min, &tm.tm_sec) != 6)
 409             return ASN1_BAD_TIMEFORMAT;
 410         if (tm.tm_year < 50)
 411             tm.tm_year += 2000;
 412         else
 413             tm.tm_year += 1900;
 414     }
 415     tm.tm_year -= 1900;
 416     tm.tm_mon -= 1;
 417     *t = _der_timegm (&tm);
 418     return 0;
 419 }
 420
 421 static int
 422 der_get_time (const unsigned char *p, size_t len,
 423               time_t *data, size_t *size)
 424 {
 425     char *times;
 426     int e;
 427
 428     if (len > len + 1 || len == 0)
 429         return ASN1_BAD_LENGTH;
 430
 431     times = malloc(len + 1);
 432     if (times == NULL)
 433         return ENOMEM;
 434     memcpy(times, p, len);
 435     times[len] = '\0';
 436     e = generalizedtime2time(times, data);
 437     free (times);
 438     if(size) *size = len;
 439     return e;
 440 }
 441
 442 int
 443 der_get_generalized_time (const unsigned char *p, size_t len,
 444                           time_t *data, size_t *size)
 445 {
 446     return der_get_time(p, len, data, size);
 447 }
 448
 449 int
 450 der_get_utctime (const unsigned char *p, size_t len,
 451                           time_t *data, size_t *size)
 452 {
 453     return der_get_time(p, len, data, size);
 454 }
 455
 456 int
 457 der_get_oid (const unsigned char *p, size_t len,
 458              heim_oid *data, size_t *size)
 459 {
 460     size_t n;
 461     size_t oldlen = len;
 462
 463     if (len < 1)
 464         return ASN1_OVERRUN;
 465
 466     if (len > len + 1)
 467         return ASN1_BAD_LENGTH;
 468
 469     if (len + 1 > UINT_MAX/sizeof(data->components[0]))
 470         return ERANGE;
 471
 472     data->components = malloc((len + 1) * sizeof(data->components[0]));
 473     if (data->components == NULL)
 474         return ENOMEM;
 475     data->components[0] = (*p) / 40;
 476     data->components[1] = (*p) % 40;
 477     --len;
 478     ++p;
 479     for (n = 2; len > 0; ++n) {
 480         unsigned u = 0, u1;
 481
 482         do {
 483             --len;
 484             u1 = u * 128 + (*p++ % 128);
 485             /* check that we don't overflow the element */
 486             if (u1 < u) {
 487                 der_free_oid(data);
 488                 return ASN1_OVERRUN;
 489             }
 490             u = u1;
 491         } while (len > 0 && p[-1] & 0x80);
 492         data->components[n] = u;
 493     }
 494     if (n > 2 && p[-1] & 0x80) {
 495         der_free_oid (data);
 496         return ASN1_OVERRUN;
 497     }
 498     data->length = n;
 499     if (size)
 500         *size = oldlen;
 501     return 0;
 502 }
 503
 504 int
 505 der_get_tag (const unsigned char *p, size_t len,
 506              Der_class *class, Der_type *type,
 507              unsigned int *tag, size_t *size)
 508 {
 509     size_t ret = 0;
 510     if (len < 1)
 511         return ASN1_OVERRUN;
 512     *class = (Der_class)(((*p) >> 6) & 0x03);
 513     *type = (Der_type)(((*p) >> 5) & 0x01);
 514     *tag = (*p) & 0x1f;
 515     p++; len--; ret++;
 516     if(*tag == 0x1f) {
 517         unsigned int continuation;
 518         unsigned int tag1;
 519         *tag = 0;
 520         do {
 521             if(len < 1)
 522                 return ASN1_OVERRUN;
 523             continuation = *p & 128;
 524             tag1 = *tag * 128 + (*p % 128);
 525             /* check that we don't overflow the tag */
 526             if (tag1 < *tag)
 527                 return ASN1_OVERFLOW;
 528             *tag = tag1;
 529             p++; len--; ret++;
 530         } while(continuation);
 531     }
 532     if(size) *size = ret;
 533     return 0;
 534 }
 535
 536 int
 537 der_match_tag (const unsigned char *p, size_t len,
 538                Der_class class, Der_type type,
 539                unsigned int tag, size_t *size)
 540 {
 541     Der_type thistype;
 542     int e;
 543
 544     e = der_match_tag2(p, len, class, &thistype, tag, size);
 545     if (e) return e;
 546     if (thistype != type) return ASN1_BAD_ID;
 547     return 0;
 548 }
 549
 550 int
 551 der_match_tag2 (const unsigned char *p, size_t len,
 552                 Der_class class, Der_type *type,
 553                 unsigned int tag, size_t *size)
 554 {
 555     size_t l;
 556     Der_class thisclass;
 557     unsigned int thistag;
 558     int e;
 559
 560     e = der_get_tag (p, len, &thisclass, type, &thistag, &l);
 561     if (e) return e;
 562     if (class != thisclass)
 563         return ASN1_BAD_ID;
 564     if(tag > thistag)
 565         return ASN1_MISPLACED_FIELD;
 566     if(tag < thistag)
 567         return ASN1_MISSING_FIELD;
 568     if(size) *size = l;
 569     return 0;
 570 }
 571
 572 int
 573 der_match_tag_and_length (const unsigned char *p, size_t len,
 574                           Der_class class, Der_type *type, unsigned int tag,
 575                           size_t *length_ret, size_t *size)
 576 {
 577     size_t l, ret = 0;
 578     int e;
 579
 580     e = der_match_tag2 (p, len, class, type, tag, &l);
 581     if (e) return e;
 582     p += l;
 583     len -= l;
 584     ret += l;
 585     e = der_get_length (p, len, length_ret, &l);
 586     if (e) return e;
 587     if(size) *size = ret + l;
 588     return 0;
 589 }
 590
 591
 592
 593 /*
 594  * Old versions of DCE was based on a very early beta of the MIT code,
 595  * which used MAVROS for ASN.1 encoding. MAVROS had the interesting
 596  * feature that it encoded data in the forward direction, which has
 597  * it's problems, since you have no idea how long the data will be
 598  * until after you're done. MAVROS solved this by reserving one byte
 599  * for length, and later, if the actual length was longer, it reverted
 600  * to indefinite, BER style, lengths. The version of MAVROS used by
 601  * the DCE people could apparently generate correct X.509 DER encodings, and
 602  * did this by making space for the length after encoding, but
 603  * unfortunately this feature wasn't used with Kerberos.
 604  */
 605
 606 int
 607 _heim_fix_dce(size_t reallen, size_t *len)
 608 {
 609     if(reallen == ASN1_INDEFINITE)
 610         return 1;
 611     if(*len < reallen)
 612         return -1;
 613     *len = reallen;
 614     return 0;
 615 }
 616
 617 int
 618 der_get_bit_string (const unsigned char *p, size_t len,
 619                     heim_bit_string *data, size_t *size)
 620 {
 621     if (len < 1)
 622         return ASN1_OVERRUN;
 623     if (p[0] > 7)
 624         return ASN1_BAD_FORMAT;
 625     if (len - 1 == 0 && p[0] != 0)
 626         return ASN1_BAD_FORMAT;
 627     /* check if any of the three upper bits are set
 628      * any of them will cause a interger overrun */
 629     if ((len - 1) >> (sizeof(len) * 8 - 3))
 630         return ASN1_OVERRUN;
 631     data->length = (len - 1) * 8;
 632     data->data = malloc(len - 1);
 633     if (data->data == NULL && (len - 1) != 0)
 634         return ENOMEM;
 635     /* copy data is there is data to copy */
 636     if (len - 1 != 0) {
 637       memcpy (data->data, p + 1, len - 1);
 638       data->length -= p[0];
 639     }
 640     if(size) *size = len;
 641     return 0;
 642 }