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) {
 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         data->data = malloc(data->length);
 358         if (data->data == NULL) {
 359             data->length = 0;
 360             if (size)
 361                 *size = 0;
 362             return ENOMEM;
 363         }
 364         q = &((unsigned char*)data->data)[data->length - 1];
 365         p += data->length - 1;
 366         while (q >= (unsigned char*)data->data) {
 367             *q = *p ^ 0xff;
 368             if (carry)
 369                 carry = !++*q;
 370             p--;
 371             q--;
 372         }
 373     } else {
 374         data->negative = 0;
 375         data->length = len;
 376
 377         if (p[0] == 0) {
 378             p++;
 379             data->length--;
 380         }
 381         data->data = malloc(data->length);
 382         if (data->data == NULL && data->length != 0) {
 383             data->length = 0;
 384             if (size)
 385                 *size = 0;
 386             return ENOMEM;
 387         }
 388         memcpy(data->data, p, data->length);
 389     }
 390     if (size)
 391         *size = len;
 392     return 0;
 393 }
 394
 395 static int
 396 generalizedtime2time (const char *s, time_t *t)
 397 {
 398     struct tm tm;
 399
 400     memset(&tm, 0, sizeof(tm));
 401     if (sscanf (s, "%04d%02d%02d%02d%02d%02dZ",
 402                 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 403                 &tm.tm_min, &tm.tm_sec) != 6) {
 404         if (sscanf (s, "%02d%02d%02d%02d%02d%02dZ",
 405                     &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 406                     &tm.tm_min, &tm.tm_sec) != 6)
 407             return ASN1_BAD_TIMEFORMAT;
 408         if (tm.tm_year < 50)
 409             tm.tm_year += 2000;
 410         else
 411             tm.tm_year += 1900;
 412     }
 413     tm.tm_year -= 1900;
 414     tm.tm_mon -= 1;
 415     *t = _der_timegm (&tm);
 416     return 0;
 417 }
 418
 419 static int
 420 der_get_time (const unsigned char *p, size_t len,
 421               time_t *data, size_t *size)
 422 {
 423     char *times;
 424     int e;
 425
 426     if (len > len + 1 || len == 0)
 427         return ASN1_BAD_LENGTH;
 428
 429     times = malloc(len + 1);
 430     if (times == NULL)
 431         return ENOMEM;
 432     memcpy(times, p, len);
 433     times[len] = '\0';
 434     e = generalizedtime2time(times, data);
 435     free (times);
 436     if(size) *size = len;
 437     return e;
 438 }
 439
 440 int
 441 der_get_generalized_time (const unsigned char *p, size_t len,
 442                           time_t *data, size_t *size)
 443 {
 444     return der_get_time(p, len, data, size);
 445 }
 446
 447 int
 448 der_get_utctime (const unsigned char *p, size_t len,
 449                           time_t *data, size_t *size)
 450 {
 451     return der_get_time(p, len, data, size);
 452 }
 453
 454 int
 455 der_get_oid (const unsigned char *p, size_t len,
 456              heim_oid *data, size_t *size)
 457 {
 458     size_t n;
 459     size_t oldlen = len;
 460
 461     if (len < 1)
 462         return ASN1_OVERRUN;
 463
 464     if (len > len + 1)
 465         return ASN1_BAD_LENGTH;
 466
 467     if (len + 1 > UINT_MAX/sizeof(data->components[0]))
 468         return ERANGE;
 469
 470     data->components = malloc((len + 1) * sizeof(data->components[0]));
 471     if (data->components == NULL)
 472         return ENOMEM;
 473     data->components[0] = (*p) / 40;
 474     data->components[1] = (*p) % 40;
 475     --len;
 476     ++p;
 477     for (n = 2; len > 0; ++n) {
 478         unsigned u = 0, u1;
 479
 480         do {
 481             --len;
 482             u1 = u * 128 + (*p++ % 128);
 483             /* check that we don't overflow the element */
 484             if (u1 < u) {
 485                 der_free_oid(data);
 486                 return ASN1_OVERRUN;
 487             }
 488             u = u1;
 489         } while (len > 0 && p[-1] & 0x80);
 490         data->components[n] = u;
 491     }
 492     if (n > 2 && p[-1] & 0x80) {
 493         der_free_oid (data);
 494         return ASN1_OVERRUN;
 495     }
 496     data->length = n;
 497     if (size)
 498         *size = oldlen;
 499     return 0;
 500 }
 501
 502 int
 503 der_get_tag (const unsigned char *p, size_t len,
 504              Der_class *class, Der_type *type,
 505              unsigned int *tag, size_t *size)
 506 {
 507     size_t ret = 0;
 508     if (len < 1)
 509         return ASN1_OVERRUN;
 510     *class = (Der_class)(((*p) >> 6) & 0x03);
 511     *type = (Der_type)(((*p) >> 5) & 0x01);
 512     *tag = (*p) & 0x1f;
 513     p++; len--; ret++;
 514     if(*tag == 0x1f) {
 515         unsigned int continuation;
 516         unsigned int tag1;
 517         *tag = 0;
 518         do {
 519             if(len < 1)
 520                 return ASN1_OVERRUN;
 521             continuation = *p & 128;
 522             tag1 = *tag * 128 + (*p % 128);
 523             /* check that we don't overflow the tag */
 524             if (tag1 < *tag)
 525                 return ASN1_OVERFLOW;
 526             *tag = tag1;
 527             p++; len--; ret++;
 528         } while(continuation);
 529     }
 530     if(size) *size = ret;
 531     return 0;
 532 }
 533
 534 int
 535 der_match_tag (const unsigned char *p, size_t len,
 536                Der_class class, Der_type type,
 537                unsigned int tag, size_t *size)
 538 {
 539     Der_type thistype;
 540     int e;
 541
 542     e = der_match_tag2(p, len, class, &thistype, tag, size);
 543     if (e) return e;
 544     if (thistype != type) return ASN1_BAD_ID;
 545     return 0;
 546 }
 547
 548 int
 549 der_match_tag2 (const unsigned char *p, size_t len,
 550                 Der_class class, Der_type *type,
 551                 unsigned int tag, size_t *size)
 552 {
 553     size_t l;
 554     Der_class thisclass;
 555     unsigned int thistag;
 556     int e;
 557
 558     e = der_get_tag (p, len, &thisclass, type, &thistag, &l);
 559     if (e) return e;
 560     if (class != thisclass)
 561         return ASN1_BAD_ID;
 562     if(tag > thistag)
 563         return ASN1_MISPLACED_FIELD;
 564     if(tag < thistag)
 565         return ASN1_MISSING_FIELD;
 566     if(size) *size = l;
 567     return 0;
 568 }
 569
 570 int
 571 der_match_tag_and_length (const unsigned char *p, size_t len,
 572                           Der_class class, Der_type *type, unsigned int tag,
 573                           size_t *length_ret, size_t *size)
 574 {
 575     size_t l, ret = 0;
 576     int e;
 577
 578     e = der_match_tag2 (p, len, class, type, tag, &l);
 579     if (e) return e;
 580     p += l;
 581     len -= l;
 582     ret += l;
 583     e = der_get_length (p, len, length_ret, &l);
 584     if (e) return e;
 585     if(size) *size = ret + l;
 586     return 0;
 587 }
 588
 589
 590
 591 /*
 592  * Old versions of DCE was based on a very early beta of the MIT code,
 593  * which used MAVROS for ASN.1 encoding. MAVROS had the interesting
 594  * feature that it encoded data in the forward direction, which has
 595  * it's problems, since you have no idea how long the data will be
 596  * until after you're done. MAVROS solved this by reserving one byte
 597  * for length, and later, if the actual length was longer, it reverted
 598  * to indefinite, BER style, lengths. The version of MAVROS used by
 599  * the DCE people could apparently generate correct X.509 DER encodings, and
 600  * did this by making space for the length after encoding, but
 601  * unfortunately this feature wasn't used with Kerberos.
 602  */
 603
 604 int
 605 _heim_fix_dce(size_t reallen, size_t *len)
 606 {
 607     if(reallen == ASN1_INDEFINITE)
 608         return 1;
 609     if(*len < reallen)
 610         return -1;
 611     *len = reallen;
 612     return 0;
 613 }
 614
 615 int
 616 der_get_bit_string (const unsigned char *p, size_t len,
 617                     heim_bit_string *data, size_t *size)
 618 {
 619     if (len < 1)
 620         return ASN1_OVERRUN;
 621     if (p[0] > 7)
 622         return ASN1_BAD_FORMAT;
 623     if (len - 1 == 0 && p[0] != 0)
 624         return ASN1_BAD_FORMAT;
 625     /* check if any of the three upper bits are set
 626      * any of them will cause a interger overrun */
 627     if ((len - 1) >> (sizeof(len) * 8 - 3))
 628         return ASN1_OVERRUN;
 629     data->length = (len - 1) * 8;
 630     data->data = malloc(len - 1);
 631     if (data->data == NULL && (len - 1) != 0)
 632         return ENOMEM;
 633     /* copy data is there is data to copy */
 634     if (len - 1 != 0) {
 635       memcpy (data->data, p + 1, len - 1);
 636       data->length -= p[0];
 637     }
 638     if(size) *size = len;
 639     return 0;
 640 }