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 RCSID("$Id$");
  37
  38 #include <version.h>
  39
  40 /*
  41  * All decoding functions take a pointer `p' to first position in
  42  * which to read, from the left, `len' which means the maximum number
  43  * of characters we are able to read, `ret' were the value will be
  44  * returned and `size' where the number of used bytes is stored.
  45  * Either 0 or an error code is returned.
  46  */
  47
  48 int
  49 der_get_unsigned (const unsigned char *p, size_t len,
  50                   unsigned *ret, size_t *size)
  51 {
  52     unsigned val = 0;
  53     size_t oldlen = len;
  54
  55     if (len == sizeof(unsigned) + 1 && p[0] == 0)
  56         ;
  57     else if (len > sizeof(unsigned))
  58         return ASN1_OVERRUN;
  59
  60     while (len--)
  61         val = val * 256 + *p++;
  62     *ret = val;
  63     if(size) *size = oldlen;
  64     return 0;
  65 }
  66
  67 int
  68 der_get_integer (const unsigned char *p, size_t len,
  69                  int *ret, size_t *size)
  70 {
  71     int val = 0;
  72     size_t oldlen = len;
  73
  74     if (len > sizeof(int))
  75         return ASN1_OVERRUN;
  76
  77     if (len > 0) {
  78         val = (signed char)*p++;
  79         while (--len)
  80             val = val * 256 + *p++;
  81     }
  82     *ret = val;
  83     if(size) *size = oldlen;
  84     return 0;
  85 }
  86
  87 int
  88 der_get_length (const unsigned char *p, size_t len,
  89                 size_t *val, size_t *size)
  90 {
  91     size_t v;
  92
  93     if (len <= 0)
  94         return ASN1_OVERRUN;
  95     --len;
  96     v = *p++;
  97     if (v < 128) {
  98         *val = v;
  99         if(size) *size = 1;
 100     } else {
 101         int e;
 102         size_t l;
 103         unsigned tmp;
 104
 105         if(v == 0x80){
 106             *val = ASN1_INDEFINITE;
 107             if(size) *size = 1;
 108             return 0;
 109         }
 110         v &= 0x7F;
 111         if (len < v)
 112             return ASN1_OVERRUN;
 113         e = der_get_unsigned (p, v, &tmp, &l);
 114         if(e) return e;
 115         *val = tmp;
 116         if(size) *size = l + 1;
 117     }
 118     return 0;
 119 }
 120
 121 int
 122 der_get_boolean(const unsigned char *p, size_t len, int *data, size_t *size)
 123 {
 124     if(len < 1)
 125         return ASN1_OVERRUN;
 126     if(*p != 0)
 127         *data = 1;
 128     else
 129         *data = 0;
 130     *size = 1;
 131     return 0;
 132 }
 133
 134 int
 135 der_get_general_string (const unsigned char *p, size_t len,
 136                         heim_general_string *str, size_t *size)
 137 {
 138     const unsigned char *p1;
 139     char *s;
 140
 141     p1 = memchr(p, 0, len);
 142     if (p1 != NULL) {
 143         /*
 144          * Allow trailing NULs. We allow this since MIT Kerberos sends
 145          * an strings in the NEED_PREAUTH case that includes a
 146          * trailing NUL.
 147          */
 148         while (p1 - p < len && *p1 == '\0')
 149             p1++;
 150        if (p1 - p != len)
 151             return ASN1_BAD_CHARACTER;
 152     }
 153     if (len > len + 1)
 154         return ASN1_BAD_LENGTH;
 155
 156     s = malloc (len + 1);
 157     if (s == NULL)
 158         return ENOMEM;
 159     memcpy (s, p, len);
 160     s[len] = '\0';
 161     *str = s;
 162     if(size) *size = len;
 163     return 0;
 164 }
 165
 166 int
 167 der_get_utf8string (const unsigned char *p, size_t len,
 168                     heim_utf8_string *str, size_t *size)
 169 {
 170     return der_get_general_string(p, len, str, size);
 171 }
 172
 173 int
 174 der_get_printable_string (const unsigned char *p, size_t len,
 175                           heim_printable_string *str, size_t *size)
 176 {
 177     return der_get_general_string(p, len, str, size);
 178 }
 179
 180 int
 181 der_get_ia5_string (const unsigned char *p, size_t len,
 182                     heim_ia5_string *str, size_t *size)
 183 {
 184     return der_get_general_string(p, len, str, size);
 185 }
 186
 187 int
 188 der_get_bmp_string (const unsigned char *p, size_t len,
 189                     heim_bmp_string *data, size_t *size)
 190 {
 191     size_t i;
 192
 193     if (len & 1)
 194         return ASN1_BAD_FORMAT;
 195     data->length = len / 2;
 196     if (data->length > UINT_MAX/sizeof(data->data[0]))
 197         return ERANGE;
 198     data->data = malloc(data->length * sizeof(data->data[0]));
 199     if (data->data == NULL && data->length != 0)
 200         return ENOMEM;
 201
 202     for (i = 0; i < data->length; i++) {
 203         data->data[i] = (p[0] << 8) | p[1];
 204         p += 2;
 205     }
 206     if (size) *size = len;
 207
 208     return 0;
 209 }
 210
 211 int
 212 der_get_universal_string (const unsigned char *p, size_t len,
 213                           heim_universal_string *data, size_t *size)
 214 {
 215     size_t i;
 216
 217     if (len & 3)
 218         return ASN1_BAD_FORMAT;
 219     data->length = len / 4;
 220     if (data->length > UINT_MAX/sizeof(data->data[0]))
 221         return ERANGE;
 222     data->data = malloc(data->length * sizeof(data->data[0]));
 223     if (data->data == NULL && data->length != 0)
 224         return ENOMEM;
 225
 226     for (i = 0; i < data->length; i++) {
 227         data->data[i] = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
 228         p += 4;
 229     }
 230     if (size) *size = len;
 231     return 0;
 232 }
 233
 234 int
 235 der_get_visible_string (const unsigned char *p, size_t len,
 236                         heim_visible_string *str, size_t *size)
 237 {
 238     return der_get_general_string(p, len, str, size);
 239 }
 240
 241 int
 242 der_get_octet_string (const unsigned char *p, size_t len,
 243                       heim_octet_string *data, size_t *size)
 244 {
 245     data->length = len;
 246     data->data = malloc(len);
 247     if (data->data == NULL && data->length != 0)
 248         return ENOMEM;
 249     memcpy (data->data, p, len);
 250     if(size) *size = len;
 251     return 0;
 252 }
 253
 254 int
 255 der_get_heim_integer (const unsigned char *p, size_t len,
 256                       heim_integer *data, size_t *size)
 257 {
 258     data->length = 0;
 259     data->negative = 0;
 260     data->data = NULL;
 261
 262     if (len == 0) {
 263         if (size)
 264             *size = 0;
 265         return 0;
 266     }
 267     if (p[0] & 0x80) {
 268         unsigned char *q;
 269         int carry = 1;
 270         data->negative = 1;
 271
 272         data->length = len;
 273
 274         if (p[0] == 0xff) {
 275             p++;
 276             data->length--;
 277         }
 278         data->data = malloc(data->length);
 279         if (data->data == NULL) {
 280             data->length = 0;
 281             if (size)
 282                 *size = 0;
 283             return ENOMEM;
 284         }
 285         q = &((unsigned char*)data->data)[data->length - 1];
 286         p += data->length - 1;
 287         while (q >= (unsigned char*)data->data) {
 288             *q = *p ^ 0xff;
 289             if (carry)
 290                 carry = !++*q;
 291             p--;
 292             q--;
 293         }
 294     } else {
 295         data->negative = 0;
 296         data->length = len;
 297
 298         if (p[0] == 0) {
 299             p++;
 300             data->length--;
 301         }
 302         data->data = malloc(data->length);
 303         if (data->data == NULL && data->length != 0) {
 304             data->length = 0;
 305             if (size)
 306                 *size = 0;
 307             return ENOMEM;
 308         }
 309         memcpy(data->data, p, data->length);
 310     }
 311     if (size)
 312         *size = len;
 313     return 0;
 314 }
 315
 316 static int
 317 generalizedtime2time (const char *s, time_t *t)
 318 {
 319     struct tm tm;
 320
 321     memset(&tm, 0, sizeof(tm));
 322     if (sscanf (s, "%04d%02d%02d%02d%02d%02dZ",
 323                 &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 324                 &tm.tm_min, &tm.tm_sec) != 6) {
 325         if (sscanf (s, "%02d%02d%02d%02d%02d%02dZ",
 326                     &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
 327                     &tm.tm_min, &tm.tm_sec) != 6)
 328             return ASN1_BAD_TIMEFORMAT;
 329         if (tm.tm_year < 50)
 330             tm.tm_year += 2000;
 331         else
 332             tm.tm_year += 1900;
 333     }
 334     tm.tm_year -= 1900;
 335     tm.tm_mon -= 1;
 336     *t = _der_timegm (&tm);
 337     return 0;
 338 }
 339
 340 static int
 341 der_get_time (const unsigned char *p, size_t len,
 342               time_t *data, size_t *size)
 343 {
 344     char *times;
 345     int e;
 346
 347     if (len > len + 1 || len == 0)
 348         return ASN1_BAD_LENGTH;
 349
 350     times = malloc(len + 1);
 351     if (times == NULL)
 352         return ENOMEM;
 353     memcpy(times, p, len);
 354     times[len] = '\0';
 355     e = generalizedtime2time(times, data);
 356     free (times);
 357     if(size) *size = len;
 358     return e;
 359 }
 360
 361 int
 362 der_get_generalized_time (const unsigned char *p, size_t len,
 363                           time_t *data, size_t *size)
 364 {
 365     return der_get_time(p, len, data, size);
 366 }
 367
 368 int
 369 der_get_utctime (const unsigned char *p, size_t len,
 370                           time_t *data, size_t *size)
 371 {
 372     return der_get_time(p, len, data, size);
 373 }
 374
 375 int
 376 der_get_oid (const unsigned char *p, size_t len,
 377              heim_oid *data, size_t *size)
 378 {
 379     size_t n;
 380     size_t oldlen = len;
 381
 382     if (len < 1)
 383         return ASN1_OVERRUN;
 384
 385     if (len > len + 1)
 386         return ASN1_BAD_LENGTH;
 387
 388     if (len + 1 > UINT_MAX/sizeof(data->components[0]))
 389         return ERANGE;
 390
 391     data->components = malloc((len + 1) * sizeof(data->components[0]));
 392     if (data->components == NULL)
 393         return ENOMEM;
 394     data->components[0] = (*p) / 40;
 395     data->components[1] = (*p) % 40;
 396     --len;
 397     ++p;
 398     for (n = 2; len > 0; ++n) {
 399         unsigned u = 0, u1;
 400
 401         do {
 402             --len;
 403             u1 = u * 128 + (*p++ % 128);
 404             /* check that we don't overflow the element */
 405             if (u1 < u) {
 406                 der_free_oid(data);
 407                 return ASN1_OVERRUN;
 408             }
 409             u = u1;
 410         } while (len > 0 && p[-1] & 0x80);
 411         data->components[n] = u;
 412     }
 413     if (n > 2 && p[-1] & 0x80) {
 414         der_free_oid (data);
 415         return ASN1_OVERRUN;
 416     }
 417     data->length = n;
 418     if (size)
 419         *size = oldlen;
 420     return 0;
 421 }
 422
 423 int
 424 der_get_tag (const unsigned char *p, size_t len,
 425              Der_class *class, Der_type *type,
 426              unsigned int *tag, size_t *size)
 427 {
 428     size_t ret = 0;
 429     if (len < 1)
 430         return ASN1_OVERRUN;
 431     *class = (Der_class)(((*p) >> 6) & 0x03);
 432     *type = (Der_type)(((*p) >> 5) & 0x01);
 433     *tag = (*p) & 0x1f;
 434     p++; len--; ret++;
 435     if(*tag == 0x1f) {
 436         unsigned int continuation;
 437         unsigned int tag1;
 438         *tag = 0;
 439         do {
 440             if(len < 1)
 441                 return ASN1_OVERRUN;
 442             continuation = *p & 128;
 443             tag1 = *tag * 128 + (*p % 128);
 444             /* check that we don't overflow the tag */
 445             if (tag1 < *tag)
 446                 return ASN1_OVERFLOW;
 447             *tag = tag1;
 448             p++; len--; ret++;
 449         } while(continuation);
 450     }
 451     if(size) *size = ret;
 452     return 0;
 453 }
 454
 455 int
 456 der_match_tag (const unsigned char *p, size_t len,
 457                Der_class class, Der_type type,
 458                unsigned int tag, size_t *size)
 459 {
 460     size_t l;
 461     Der_class thisclass;
 462     Der_type thistype;
 463     unsigned int thistag;
 464     int e;
 465
 466     e = der_get_tag (p, len, &thisclass, &thistype, &thistag, &l);
 467     if (e) return e;
 468     if (class != thisclass || type != thistype)
 469         return ASN1_BAD_ID;
 470     if(tag > thistag)
 471         return ASN1_MISPLACED_FIELD;
 472     if(tag < thistag)
 473         return ASN1_MISSING_FIELD;
 474     if(size) *size = l;
 475     return 0;
 476 }
 477
 478 int
 479 der_match_tag_and_length (const unsigned char *p, size_t len,
 480                           Der_class class, Der_type type, unsigned int tag,
 481                           size_t *length_ret, size_t *size)
 482 {
 483     size_t l, ret = 0;
 484     int e;
 485
 486     e = der_match_tag (p, len, class, type, tag, &l);
 487     if (e) return e;
 488     p += l;
 489     len -= l;
 490     ret += l;
 491     e = der_get_length (p, len, length_ret, &l);
 492     if (e) return e;
 493     p += l;
 494     len -= l;
 495     ret += l;
 496     if(size) *size = ret;
 497     return 0;
 498 }
 499
 500 /*
 501  * Old versions of DCE was based on a very early beta of the MIT code,
 502  * which used MAVROS for ASN.1 encoding. MAVROS had the interesting
 503  * feature that it encoded data in the forward direction, which has
 504  * it's problems, since you have no idea how long the data will be
 505  * until after you're done. MAVROS solved this by reserving one byte
 506  * for length, and later, if the actual length was longer, it reverted
 507  * to indefinite, BER style, lengths. The version of MAVROS used by
 508  * the DCE people could apparently generate correct X.509 DER encodings, and
 509  * did this by making space for the length after encoding, but
 510  * unfortunately this feature wasn't used with Kerberos.
 511  */
 512
 513 int
 514 _heim_fix_dce(size_t reallen, size_t *len)
 515 {
 516     if(reallen == ASN1_INDEFINITE)
 517         return 1;
 518     if(*len < reallen)
 519         return -1;
 520     *len = reallen;
 521     return 0;
 522 }
 523
 524 int
 525 der_get_bit_string (const unsigned char *p, size_t len,
 526                     heim_bit_string *data, size_t *size)
 527 {
 528     if (len < 1)
 529         return ASN1_OVERRUN;
 530     if (p[0] > 7)
 531         return ASN1_BAD_FORMAT;
 532     if (len - 1 == 0 && p[0] != 0)
 533         return ASN1_BAD_FORMAT;
 534     /* check if any of the three upper bits are set
 535      * any of them will cause a interger overrun */
 536     if ((len - 1) >> (sizeof(len) * 8 - 3))
 537         return ASN1_OVERRUN;
 538     data->length = (len - 1) * 8;
 539     data->data = malloc(len - 1);
 540     if (data->data == NULL && (len - 1) != 0)
 541         return ENOMEM;
 542     memcpy (data->data, p + 1, len - 1);
 543     data->length -= p[0];
 544     if(size) *size = len;
 545     return 0;
 546 }